PONTIAC ZONE TECH FORUMS
 

Go Back   PONTIAC ZONE TECH FORUMS >
Engine Tech
> Grape Vine - General Discussion
User Name
Password

Grape Vine - General Discussion Shop Talk - Bench Racing, No political or religious topics are allowed.

sponser links

Reply
 
Thread Tools
Old 02-24-08, 11:15PM   #1
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default flow bench comparison- Superflow vs. custom entire flow path- CV1 heads get thumbs up

first picture is Widmer's flow bench, patterned after Smokey's, but with more modern measuring devices and computerized. He developed the winning Pro Stock Ford shotgun Hemi heads, and 351C NASCAR heads early 1980's- that's him standing by it



compare Widmer's "complete flow path" custom bench, to a Superflow 1020 in picture #2- the SF is a nice high end bench, but it's a bare head on a flow tube- no intake, carb, block, header.

http://www.superflow.com/flowbenches/index_1157.cfm



which bench most accurately duplicates the actual running engine ? common sense says the engine doesn't run a bare head down the track



I have exchanged emails with Widmer a few times in recent years, most recently last week- and sent him pics of the new CV-1 heads. he looked over Jim Sammon's website, and gave the project a thumbs up- here's his reply:

----- Original Message -----
Sent: Monday, February 18, 2008 5:39 PM
Subject: Re: hello

Hey Charlie,
Those are some really nice looking heads. They should finally put Pontiacs on par with other good-breathing engines.
I think you have to agree that with all the good castings and CNC "everything", we're definitely in the golden-age of engine building today.
I'm having more fun with this stuff than I ever did with Nascar!...and they haven't seen nothin' yet.
I still can't wait to get to work (my hobby shop) everyday, however, once I begin to slow down, I will begin on a book....probably with Jim McFarland's help.
I appreciate your email and the link to the new Pontiac pieces.
Thanks again,
Larry
Attached Thumbnails
Click image for larger version

Name:	Widmer's bench.jpg
Views:	399
Size:	35.1 KB
ID:	15100   Click image for larger version

Name:	superflow.jpg
Views:	329
Size:	53.4 KB
ID:	15101  
Zedo is offline   Reply With Quote
Old 02-25-08, 02:19AM   #2
GET IT ON
Pontiholic
 
Join Date: Dec 2006
Location: Pacific, Missouri
Posts: 1,112
Default

Coming from Larry Widmer, That's a huge compliment !!! If only some on here knew half what he does.
GET IT ON is offline   Reply With Quote
Old 02-25-08, 04:31AM   #3
Pontiac Jack
M/T Hemi Guru
 
Pontiac Jack's Avatar
 
Join Date: Mar 2007
Location: Phelps, NY
Posts: 697
Default

Paired with McFarland, that will be one heck of a good book!
Pontiac Jack is offline   Reply With Quote
Old 02-25-08, 09:14AM   #4
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default

Quote:
Originally Posted by GET IT ON View Post
Coming from Larry Widmer, That's a huge compliment !!! If only some on here knew half what he does.


he told me, he used to tinker with Pontiac SD455 heads at one time

he got tired of the NASCAR and NHRA bullshit- they'd buy his heads, pay primo price for first pair, win with the heads, then copy them and badmouth him later

here's the Bob Glidden Pro Stock story- IMO Glidden gave him a bum steer-

http://www.theoldone.com/archive/too_on_bob_glidden.htm

"As I mentioned in my brief reply, the heads in question were a set designed for a blown drag boat application, and Goletta Marine was the customer. The head castings were designed for Alan Root's all aluminum BOSS 429 engine packages. The designer of the heads was Tom Roberts who at the time worked for Nick Arias, in fact Arias was a 30% partner with Root. Their redesign of the BOSS components began in 1983, and the first parts were available in late ' 83 - early ' 84. The head redesign reflected the typical Arias port configuration which favored blown applications. Blown fuel was what Nick and Alan were after, however, as there were no takers, other classes were considered, i.e. ProStock.
In late ' 83 Alan and I struck a deal to make the heads more appealing to the Pro ranks. This program included a crash effort to make the standard Arias Root head work, and I immediately began a redesign of the head incorporating swirl pads in the chamber, redesign of the inlet port to promote mixture swirl, and a major redesign of the exhaust side using my "super critical area rule" to achieve supersonic exhaust flow. The prototype heads were the std. AR castings with several pounds of my aluminum welding rod used to reshape all the necessary surfaces. The castings were then normalized, and re-heat treated to spec. All surfaces were remachined, and the new chamber and ports were laboriously executed, and the heads flowed as the formulas' predicted. During this same period Alan and I felt that there would be a considerable market for finished heads and manifolds, as well as proper pistons, cams, and advice on rod length, stroke, bore, etc. In other words, all the right pieces, some assembly required. The Super Swirl heads (complete), and worked manifold were to be priced at $10 K per "package", and available in no other form.....remember, however, this was a separate head entirely from the std. AR 429 "HIGH PORT" heads. In order to get the ball rolling, we wrote a computer program to allow a multiaxis mill to "rough in" the chambers, and I spent considerable time at Aerocast in LA scraping the sand cores to produce 10 pair immediately without welding. I also began revision of new tooling to allow casting without the custom scraping, so when I received the heads we at Endyn would do all finish machining, porting, assembly, etc., and the "super swirl" heads would go directly to the customer flow sheets and all other engineering data included. The head package was given part # M-6049-A443* by Ford and included(without) picture in the 1985 Catalog. We ran our prototype super swirl engine in November,84, and produced the dyno figures partially quoted in the soft head article, however, max. power was never revealed until my lengthy book to Sentiniel, this AM. Bob Glidden heard about the dyno run at the SEMA show which was going at the time, and wanted to buy the engine, and all the other hand scraped castings we were finishing. The price was right, and as the NASCAR programs needed tending , we agreed.....thinking that our head deal with Ford was intact. Little did I know that Bob had negotiated to buy out Nick Arias share of AR, and of course he then went directly to Ford and mandated that the "super swirl" head program be cancelled. It was and that's that. Bob didn't want anyone else having access to the same "stuff" he was running, and I can't blame him.
Now I'll address your head related questions: With the exception of blown applications, ports don't just flow one direction. Intake ports pulsate back and forth, and exhausts flow backwards too. This occors primarily at overlap, when the cylinder still has positive exhaust trying to exit the exhaust port ...where header back pressure is pushing backwards. Now the intake valve (which is larger in diameter) opens, and exhaust gasses seeking the path of least pressure take the easy way.....the intake port "exit". This is not a good thing because besides turning the intake port black "reversion" also contaminates the intake charge with inert gasses which will not burn again. My studies showed a direct correlation between low lift intake flow and reverse flow.....The better the low lift flow on an intake port, the better the tendency for reverse flow, or sucking exhaust. I designed my intake ports to not flow worth a shit at low lift, and also to not flow backwards. I'll not detail how, but the approach to the inlet valve seat, and its blend to the chamber are how it's accomplished....remember the seat is only the 45 degree angle that's ~ .055" wide. were not talking about the seat ring itself. The assymetric shapes I developed for that area and the last .5" of the intake port (the wierd valve job) are why the port doesn't dare flow backward, and as for low lift flow......study the piston velocity when the valve's at .150" or less. You'll find that it's so slow that the port's not being sucked on at all(relatively speaking), so big flow #'s at low lift wouldn't do you any good anyway. If I had known how to design an intake port that flowed 0 cfm. up to .150" lift, I would have, but all things considered my "weird seats" worked well for their time.
Exhaust ports: Read my Re. to RX first. I've never had much luck with performance of engines with no exhaust valves, so I've never been inclined to design exhaust ports without valves included. All I'll say is that the some flow attaches itself to the head and stem on the exhaust side, so the valve is somewhat like a guide for flow. The thing you're missing when flowing with no valve is that the valve stem represents part of the cross sectional area of the port, and, as previously stated areas are critical when dealing with velocities over mach 1. My port phylosophy has always been to calculate how much air a given displacement engine needs to run at a given rpm range (taking into account the many variables such as bore / stroke / rod length, and of course rules), and design a high velocity intake port that's not too large or so small that the velocities will cause separation of a well prepared air / fuel mixture. With valvetrain life in mind, I also attempt to achieve highest flow rates at crank angles where piston velocity is highest (greatest sucking power). If you can obtain 90% of your max. flow rate at mid lift, you don't need to run a cam with spring killing lift. As for the exhaust side, lalve lift and the additional heat kill springs, so the more you can flow, the less lift is needed, and if it's real good you don't need to open the exhaust valve before BDC on the power stroke, releasing that last bit of cylinder pressure pushing on the piston, and you can close it earlier too. Most "head experts" agree that the exhaust should flow 80% of the intake, and assuming that they're talking flow with the manifold / injector installed, and the header on the exhaust, that's ok. But if I can design an exhaust port that flows twice the intake port flow, I will, because it allows you to run less lift and duration which makes springs happy, and on an engine like the Ford BOSS 429 remember the exhaust rocker arm is about 5" long, and I don't care what you make it from, all that mass takes considerable spring to control, and the less you move it the longer all the parts last. Over the years I've had customers go in and **** up my ports so the flow will be less allowing them to run the same cam they used to. What a world. I was diagnosed with cancer in Sept.1979, a great thing to find after winning Indy 3 months earlier. Two years of continuous chemotherapy and I achieved remission, it bit my ass again after concluding the rules breaking Toyota program. Another year of chemo. and four weeks of radiation and they haven't killed me yet. One reason I'm still here is that after cutting off the bull shit with the press, and I've been able to pick and choose what I work on and who I work for, and for the most part I set the rules and the schedules.
Now I appreciate your support, and I enjoy fielding some technical questions for you guys, but I don't and won't go through this bull shit of being placed under a fuc-king microscope, and having to justify who the hell I am or "am not". As your second remission doesn't last as long as your first, that puts me 3 years "over due", and I've had so much fun with doctors, I'm gonna roll with it this next go-round, and try to leave the world a little bit better place than when I came . I'm tired, I'm irritated, and I'm pissed, and now it's time for me to quit typing and get back to something more productive than trying to convince people that I'm alive."
Zedo is offline   Reply With Quote
Old 02-25-08, 09:19AM   #5
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default

Widmer's Pro Stock engine buildups were NASA space-age technology level:


http://www.theoldone.com/archive/pro...ing-engine.htm

If you want to build an engine that will rev to an unlimited rpm, that's fine, but it really doesn't do you any good after a point because the spring pressures necessary to control valve timing, as well as other internal friction and parasitic losses will rise to a point that there's no torque, and you have to have to have torque and rpm to make hp.
High rpm is the single greatest cause of failure in "performance" engines. My definition of rpm is "Ruins Peoples Motors", and there's not a single program that I've been involved in for the last 30 years where one of the primary goals wasn't to lower the rpm range that the engine operated in.
We've never built an engine to see how high we could make it rev. We already use valve springs that cost $500.00 each, valves that cost $400.00 ea., and that's just a start. A competitive "domestic" normally aspirated ProStock drag racing engine will bring an easy $90,000.00, and it will need a total rebuild after 7 quarter mile runs. these engines are not to be confused with the supercharged fuel burning engines in Top Fuel and Funny Cars. They actually cost a lot less, and they don't turn the rpm either.
From an airflow stand point, if you try to flow enough air through any size orifice, you will finally reach a saturation point. It doesn't matter if the engine is pulling the air in (NA) or a blower is pushing it in, once you reach the "magic number", you're going to use more energy trying to move the air than you'll ever make in power.
My best advice is simple. Build a strong engine that produces a lot of torque from idle to a reasonable rpm, and leave it at that.
There are no competitions yet for making max. air flow, max. hp, or max. hp, and until someone posts some $$ for doing so, I'm not going to get envolved."
Zedo is offline   Reply With Quote
Old 02-25-08, 09:27AM   #6
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default the details

the details:

http://www.theoldone.com/archive/pro...ing-engine.htm

"I’ll begin this by first saying that there aren’t many forms of internal combustion engines, or any form of motorsports where the engine development programs have been any more challenging than in NHRA Pro Stock competition. I fully realize that this statement will draw fire, but regardless of the fact that these engines only power a vehicle a quarter mile at a time, and this is an "unlimited heads up" class, the rules governing the configuration of these engines make the design and construction of a competitive power plant very difficult. All the rules governing other "unlimited" type engines are considerably less restrictive in all other forms of competition, so I think the best place to start is with the rules.
A quick run down on NHRA"s Pro Stock engine rules will "read" like this: Engine.90 degree automotive-type V8, reciprocating, normally aspirated, single distributor, internal combustion engine. Block can be any material or manufacture, single cam. Max. bore spacing of 4.90", and max. total displacement of 500cid. Two automotive type 4 bbl. carbs, with any internal mods. No split carbs, no fuel injection (yet). Intake manifolds are unlimited in configuration, as long as they’ll fit under a single opening hood scoop with a max. height of 11". Heads must have a max. of two valves, one spark plug, and they must be "castings" with a manufacturer’s logo and pt. #. Now that’s about it, other than the fact that the fuel must be gasoline, and all components such as balancer, and flywheel must be approved. There are also fuel system safety rules, ground clearance, etc.
So, here’s the deal. We need an engine that will propel a 2350lb., front engine car down a quarter mile in less than 7.00 sec. at 200 mph. How to do?? First we study the aerodynamics of the car, the max. allowable hood scoop height (dictated by driver vision and aero studies. The chassis configuration is next with finite stress analysis a must to determine flex and resultant suspension reaction abilities. The transmission type is another variable, although, we all are using clutchless 5 speed square cut boxes currently. And then there’s the clutch. I don’t care how much power you can produce, if you can’t make the clutch slide the correct amount on launch, and each gear change, you won’t qualify. Today the 16 qualifiers are typically running within a .05 sec. separation, and there are 20 more that were within .10 sec. that will either stay and watch or head for home. Pretty competitive, relative to any other form of motorsports competition, especially when you consider that they don’t have additional laps to make up for driver error.
As I’ve never been high on running excessive rpm, we’re going to attempt to build an engine where I dictate the torque curve. Now this is a different approach for most people, since they usually adapt the car to whatever the engine "dictates", but engines are stupid, and my way is considerably less time consuming and less costly. Typically Pro cars are running almost 10,000 rpm which is really incredible when you consider the displacement and the fact that they are single cam push rod engines. The fact that they’re carbureted has absolutely no effect on their power when compared to any known digital fuel injection, assuming you’ve designed a proper intake manifold, and you understand the "black art" of carburetors.
After measuring both scoop height effectiveness and drag, the real test is the driver and his vision. It’s not likely that you’ll be afforded the luxury of the 11" scoop, but the height we can work with when combined with bottom end clearance and crank C/L will allow a maximum "package height" of 24.5 (the maximum distance from the top of the intake manifold to the crank C/L) and this number still provides the proper room on top for the carbs. and scoop relationship to work well. Next the decision to run lower rpm is examined, and a torque number is determined to be the minimum to push our combination of frictional losses, drag coefficient and frontal area to speeds of 200+. That torque value at 9,000 rpm is 792 ftlbs., or 1,360 hp. for those impressed by that #. As we’re going to run less rpm, our rpm range will be slightly wider by necessity, so the math shows that the lowest rpm we’ll encounter is 7,800. The torque necessary to overcome the shift is 852 ft.lbs. which for those who care is 1,265hp. Nasty numbers for a Detroit relic!
The bore / stroke combination for this rev. range will use a slightly longer stroke, and smaller bore, at first the first "look". This is where the package height starts affecting everything we do. Since I attempt to run a rod length to stroke ratio of 1.75 - 1, calculating the rod length combined with the compression height(distance from pin C/L to deck), and (.5 x stroke) will yield our block deck height once we settle on the stroke. The combination using 4.6" bore, and 3.75" stroke, with a 6.5" rod, and a piston with a 1.265" compression height will yield a deck height of 9.635"and the rod length to stroke ratio will be 1.73 -1 which is "good". As we’re looking for a really "fat" torque curve, we’re going to build another combination for this engine. Number (2) engine , combined will use a 3.80" stroke and a 4.57" bore combined with a 6.57" rod will again provide a rod to stroke ratio of 1.73 -1. In order to place each engines internals under the same deck height, the compression height on #2 will be 1.165" which is "doable".
So "derived from experience" I’m going to build a 498 cid. engine with two different strokes and bores. The two groups of 4 cyls. displacements will be within .01 ci. coming in at 62.29 ci. and 62.28 respectively. The geometry is 1.73 -1 on each, and the ring package will be placed in the same position despite the different compression heights. Both bores are large enough where the flow rates and swirl characteristics will be very nearly the same.
The bottom end will use a cast iron block which has been "seasoned" and stress relieved. All finish machine work will be done in house including main bearing bores, cam bore (which we’ll raise) lifter bore location, all oil passages, cylinder bores, bolt holes, and all finish interior and exterior machining. The exterior milling is for weight removal and once the mechanical operation is complete, the exterior is chemically treated to remove more material and to dispose of any tool marks which could serve as origins for stress cracks. The cam is moved up to shorten the pushrod length, and the lifter bores locations are also dictated by valve and rocker arm position. We want everything as direct as possible and no push rod angle relative to both lifter body and rocker arm. The camshaft will rotate in needle bearing housings pressed in the block, do oil isn’t a great issue. The lifters are of the roller variety, and their bodies are about twice the diameter of "stock" lifters. The lifter body is made of beryllium for weight purposes, and lifter rotation is prevented by a pin similar to a key which will ride in a slot in the bore.
The crankshaft is a non twist forging from a Japanese vendor. After rough machining it’s checked for internal and external flaws, and then the finish machining begins. We’ll use the big block Chevy main bearing size, and the rod journal will use a bearing which will have adequate width, but a specific diameter calculated to reduce bearing speed, and resultant losses. Once all the bearing surfaces are "close" the final shape of the counter weights are determined and they are machined to an aerodynamic configuration.
We elect to use titanium rods which will allow us to run tighter clearances than their aluminum counter parts. (piston to head @ .30" vs. .90") These rods cost three times more but they’re good for three times the life, or about 45 runs. The entire rotating assembly is internally balanced and ready for assembly.
The oiling system consists of a five stage dry sump pump, with external oil storage tank. The oil pan is designed with a large "kick out" on the rt. side where the oil pick-ups are located. We also fit a scraper to the shape of the rotating assy. That has about .050" clearance to shear oil from the crank / rods. The bottom of the oil pan is configured and coated to prevent oil from bouncing back up into the rotating assembly. Our pump not only removes oil but one stage is used to create a "vacuum" in the crankcase, the rest is used to pump oil back in. The engine will never have more than 1 quart of oil in it at any given time or rpm.
On top, things get interesting, because now we’re dealing with the piston domes, heads, valve events and manifolding.
During the selection of "brand" we automatically were zoned in on about 4 different heads which are legal. As we’ve had experience with these pieces before and we do not want to do a lot of welding, we’ll make runner, chamber, and water jacket cores which will fit the OE core box and provide heads with adequate material everywhere we need it. The "desirable flow #’s at all valve lifts are calculated, and the port angles and shapes are modeled to verify the characteristics. This is a critical stage as we must also design the intake manifold at the same time, and, remember, it all has to fit in the "package height" which was dictated at the beginning. We begin with the plenum top and overall volume. The volume is dictated by displacement, rpm and rod / stroke ratio, so it’s "fixed", however, a carbureted engine must have the correct runner length, angle, volume, and opening relationship relative to the carbs. throttle bores or the "vacuum signal" will not permit proper carb. function, and the engines ability to accelerate and recover from an instant drop in rpm (on shifts) will be non existent, regardless of torque and power #’s. Now we’ll begin at the top and work down. Once we have the carbs positioned correctly for easy runner entry access, we’ll determine if the intake port previously modeled can coexist with a runner of this angle. If so, we’re OK, but typically we need to go back and redesign the port to compromise its shape to allow it to be properly manifolded. We’ll go round and round and finally settle on a best of the lot. Keep in mind that this is a push rod engine, so the ports must be placed between the push rods, and remember the push rods must be as straight as possible, or valvetrain life is going to be non existent.
Things are now going to become a little more challenging. Remember that the engine has two separate sets of cylinders that do not share the same bore and stroke dimensions. The manifold runners also need to be different lengths and volumes to accomplish what we’re asking. So now we need four runners of one configuration, and four of another. We determine that the short stroke port / runner volume should be 1038.2 cc’s, and the long stroke will want 1128.6 cc’s. These volumes should maximize the cylinder’s out put in the desired rpm range.
We now design the combustion chamber and piston dome. We have various models which are known quantities, so we’ll select one that at first pass appears to want to work with bore size, port location (push rod location),etc. The primary goal is to create a really fast burn in a "big" bore, and to also allow great tuning tolerance. The other requirement is that we achieve maximum cylinder pressure well past TDC, at 20 to 30 degrees if possible. To achieve all this we’ll make sure that at TDC there’s no secondary pocketing. The chamber and piston shapes will accelerate the swirl initiated by the intake port’s flow bias, and then concentrate the swirling mixture into a small "sweet spot" near the exhaust valve, and to make things lively we’ll also put the plug in the "sweet spot" as well. The chamber shape now dictates valve location and size, however, if the valve size isn’t sufficient, we must return and look at remodeling the chamber.
I believe we have a chamber and piston dome that’ll work, and based on rpm and relative efficiency, the flow rates are determined for all areas under the lift curve, which is a function of how quickly I can open the intake valve and not exceed piston velocity for the first 12 - 14 degrees of crank rotation. Each intake valve will have it’s own lobe configuration and timing. This may seem acceptable for the differently configured cylinders, but it’s necessary to make changes on every cylinder as well to achieve our power range goals. The valve sizes will be 2.48" for the intakes and 1.87" for the exhausts. These aren’t as tight a fit in the bores as you may think, as there’ll be some compound angles involved so the valves will open to the center of the cylinder, and move away from the cylinder wall as they open. The "exit" area size for the exhaust port will be 3.04 sq. in., and the area inside the port will be as small as 2.0 sq.in., and I can’t tell you where relative to the port length as it’s highly proprietary.
The intake port cross sectional area will range from 4.84 sq.in. to a minimum of 3.23 sq. in., and again, I can’t say where these areas are located in the port. In the intake plenum chamber the runner entry will be 6.7512 sq, in. with a 1.46" radius around the runner entry.
There’s also a "black art" that I’ll mention regarding state of the art cylinder heads, and that’s steam manifolding. The design and construction are a pure art form, and if it’s not done correctly, you won’t be in the hunt. That’s all on that subject.
The flow rare for the intakes is 618 cfm @ .800" lift and 675cfm @ .800" for the exhaust ports. These values are only for comparison and are at a pressure drop of 28" H2O. We develop and flow components at "different" pressures than the "norm". The exhaust port will reach 85% of the above # by .400" lift. These lift #’s are not necessarily indicative of the lift #’s currently run in prostock as some cams yield over 1.0" net lift. I will say this, however, I feel the same way about valve lift as I do about rpm.
The material for intake valves is beryllium and the exhaust valves are titanium. The retainers are titanium, as are the valve springs which need replacement every 12 runs, and you already know the price. The shaft mount rockers are also beryllium, and the pushrods are composites.
The use of ceramic and non friction coatings is extensive on piston domes, skirts, combustion chambers, and valves. We also coat bearings, oil pump components, etc. with moly coatings.
The headers are 2.5" diameter primary ????? @ 25" long, the collectors are 4.5" dia. And 13" long after the merge is complete, and all exhaust components are ceramic coated


The carburetors are Holley 4500 series units that flow @ 1300 cfm. each. Fuel systems require a minimum 1" diameter line from the fuel cell to the carb logs, while maintaining constant pressure of 8 psi. The vent on the fuel cell must be at least .625" or you’ll starve the engine. The ignition is crank triggered MSD with multi- step rev limiters, and timing alterations.
Typical procedure is to break in the rings with a mild cam, "break-in "heads and induction components. Once complete and we see negative crankcase pressure, meaning the rings have seated, it’s time to see if the combination works.
After installing all the "good" stuff, we’ll do a quick run in to re-torque and reset the valves. The next hour is spent installing pressure transducers for each cylinder, exhaust temp. sensors, and chemical analysis probes in each primary tube, correct air ducting and inlet temp. and volume measuring instruments, and also the fuel flow and all normally used sensors. We have the ability to not only adjust carb mixture remotely, but we also can re-map the ignition timing. Dyno’s have come a long way during the last twenty years, and . Dyno’s have come a long way during the last twenty years, and we’ve attempted to stay on top of the game, as the more you can simulate in the dyno cell, the less track time is required. Aside from being able to program a drag strip, oval, or road course into the system, we also simulate G’s by mechanically tilting the entire dyno / engine combination. For lateral G. the engine is all we tilt.
We now have the ability to not only map cylinder pressure from each cylinder vs. crank angle at all rpm., analyze the combustion efficiency by looking at the gasses that are spent, but we can also read the torque of each cylinder during the tests, and when the test is complete, we can down load, and determine where we need to fine tune.
This particular engine produced slightly better numbers than we "dictated" on it’s first "run". We made some slight mixture and timing changes and found less torque but quicker acceleration. After another hard look at all the numbers, I felt that we needed to alter the cam’s lobes slightly to increase the torque overlap from the different 4 cly. Engines, but also the individual cylinders needed slightly more "spread".
Once installed and all was re-set, we realized considerably more torque than earlier(which was a surprise), but the response time was the best we’ve seen from a Pro engine. Not only did it immediately get up after the simulated shifts, but the transient response (acceleration time from point A to B) was incredible. We also observed that the best timing was 12 degrees BTDC, and the exhaust temps. were down around that 800 degree # we like. Chemically, it was also very clean so we were not only purging the area above the top ring, but also there was little that wasn’t burned. The optimum BFSC’s were all under .340 which is very good for any engine, and typical of what we’ve been seeing for the last 15 years or so. Most drag racers don’t care much about mileage though. We did a few tests to determine where the engine became semi-resonant, and although it’s a large engine, the torque extended down to some lower rpm ranges than expected, and the combustion efficiency was surprisingly good in the lower rpm ranges. Although I’ve never been to build two engines that will produce identical power, it was decided that since almost everything was digitized, we’d build a clone to play with while freshening up the customer’s engine. Or is that engine(s)???
And for all those who want compression ratio numbers, the "combustion space" volume for each cylinder equaled 43.4 cc including the head gasket. If you calculate it, please don’t tell me what it is, as it might worry me and my customers! The gas requirement was 113 octane, and the individual cylinder ignition timing was as low as 11, and as high as 13 degrees….different engines, every cylinder."
Zedo is offline   Reply With Quote
Old 02-26-08, 10:22AM   #7
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default

it takes a few times through this to understand what he's doing, but basically his Pro Stock engine, had a different cam lobe grind for every cylinder- one half the motor has a longer stroke than the other bank. One half has a different R/S ratio than other side. The intake ports flow zilch at low lift, and are unidirectional so they only flow one way- in. There's no 3 angle valve job, only one angle- why make a funnel for flow to go backwards up intake runner. 109% E/I ration, with less exhaust duration/lift/spring pressure on exhaust- to cut down overlap, heat, friction, internal HP loss, and produce higher cylinder pressure. There's a venturi located in both intake tract and exhaust tract, but he's not saying where it is- "proprietary" means highly guarded secret. He found that venturi location by flowing entire intake/exhaust tract (ala Smokey and Butler)- taking a lot of time and a complete flow path bench he built himself.

there's no way to find out about this s-hit without reading it, because the average amateur racer or hobbyist will never be at this level to do it "hands on". Average hobbyist does a stock rebuild, hotter cam, and chrome dress up goodies.

There's obviously more than one way to skin a cat. Imagine what Widmer's approach would yield on a Pontiac IA2 block with the new CV heads. It's a whole new ball game for Pontiac- as he said in his reply last week. The key is, the system needs to be developed as a complete flow path, not a bare head. Results need to be correlated/verified with dyno pulls and car track times. Simply pulling up a bare head on a flow bench, bolting it in place of your old heads, don't cut it. It may be marginally better but not maximized.

I flowed my RA V heads- 317int/202ex. Big deal- that only told me the airflow the bare heads have- it was more than stock D-ports or round ports. Since then I've tried 2 tunnel ram lids, 3 cams, 2 different piston dishes, 3 carburetors, 2 converters, 3 different deck height settings, and 3 types of PCV systems- to get it to this point streetable. Extra piston/bore and piston/pin clearance. Each carb was jetted up/down and idle mixture/off idle/power passages drilled up/filled down. Each cam was moved from straight up to advanced, and solid flat tappet and hydraulic tried. Timing curve adjusted a dozen times. I spent 3 days just degreeing the cam a variety of ways. CR ratio changed 3 times for pump gas. Converter pulled machined to open up converter/flexplate clearance. I have 4.11's that never made it in the car yet, and I've been wrenching on this same 470 RA V combo since 1998. That's just what I remember. The heads themselves are only a starting point. And it's only a street car.

point is total combination must match the heads. You just don't flow bare heads, bolt on heads and fly, with same cam-intake-carb-headers-timing-tuneup-etc from old setup. It may take a lot more work and YEARS to get the combination those new CV heads like.
Zedo is offline   Reply With Quote
Old 02-26-08, 12:13PM   #8
EC
Registered User
 
EC's Avatar
 
Join Date: Aug 2002
Location: naperville Il
Posts: 1,946
Default

Zedo can you please explain how one bank can have a longer stroke than the other bank?
EC is offline   Reply With Quote
Old 02-26-08, 01:32PM   #9
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default

Quote:
Originally Posted by EC View Post
Zedo can you please explain how one bank can have a longer stroke than the other bank?

read what he said:

"The combination using 4.6" bore, and 3.75" stroke, with a 6.5" rod, and a piston with a 1.265" compression height will yield a deck height of 9.635"and the rod length to stroke ratio will be 1.73 -1 which is "good". As we’re looking for a really "fat" torque curve, we’re going to build another combination for this engine. Number (2) engine , combined will use a 3.80" stroke and a 4.57" bore combined with a 6.57" rod will again provide a rod to stroke ratio of 1.73 -1. In order to place each engines internals under the same deck height, the compression height on #2 will be 1.165" which is "doable".
So "derived from experience" I’m going to build a 498 cid. engine with two different strokes and bores. The two groups of 4 cyls. displacements will be within .01 ci. coming in at 62.29 ci. and 62.28 respectively. The geometry is 1.73 -1 on each, and the ring package will be placed in the same position despite the different compression heights. Both bores are large enough where the flow rates and swirl characteristics will be very nearly the same.
The bottom end will use a cast iron block which has been "seasoned" and stress relieved. "



perhaps 2 offset rod journals on each crankpin, like on a GM V-6, 2.8 liter I rebuilt one time, from an S-10 truck

pretty crafty stuff- he machined it himself
Zedo is offline   Reply With Quote
Old 02-26-08, 05:09PM   #10
Gach
Administrator
 
Gach's Avatar
 
Join Date: May 2003
Location: ....
Posts: 19,506
Default

I thought this was a very interesting statement..so much for
low lift flow...LOL...I've always had revision showing in the
intake and head port...on the iron heads.

PS: really good read.

Quote:
The better the low lift flow on an intake port, the better the tendency for reverse flow, or sucking exhaust. I designed my intake ports to not flow worth a shit at low lift, and also to not flow backwards. I'll not detail how, but the approach to the inlet valve seat, and its blend to the chamber are how it's accomplished....remember the seat is only the 45 degree angle that's ~ .055" wide. were not talking about the seat ring itself. The assymetric shapes I developed for that area and the last .5" of the intake port (the wierd valve job) are why the port doesn't dare flow backward, and as for low lift flow......study the piston velocity when the valve's at .150" or less. You'll find that it's so slow that the port's not being sucked on at all(relatively speaking), so big flow #'s at low lift wouldn't do you any good anyway. If I had known how to design an intake port that flowed 0 cfm. up to .150" lift, I would have, but all things considered my "weird seats" worked well for their time.
Gach is offline   Reply With Quote
Old 02-26-08, 05:16PM   #11
Gach
Administrator
 
Gach's Avatar
 
Join Date: May 2003
Location: ....
Posts: 19,506
Default

Another interesting statement..

Quote:
[1. My port philosophy has always been to calculate how much air a given displacement engine needs to run at a given rpm range (taking into account the many variables such as bore / stroke / rod length, and of course rules), and design a high velocity intake port that's not too large or so small that the velocities will cause separation of a well prepared air / fuel mixture. With valve train life in mind, I also attempt to achieve highest flow rates at crank angles where piston velocity is highest (greatest sucking power). If you can obtain 90% of your max. flow rate at mid lift, you don't need to run a cam with spring killing lift.
mine was 85%...I called it cam flow...LOL

This is good info..but probably over most guys heads.
Gach is offline   Reply With Quote
Old 02-26-08, 10:48PM   #12
Zedo
prodigal son
 
Zedo's Avatar
 
Join Date: Apr 2006
Location: USA
Posts: 4,091
Default

yeh, what an eye-opener that is, big low lift flow numbers promote reversion- we all know a few well-known racers who were pushing low-lift flow, remember ?

the 400 with 041 cam engine I ran 20 years ago, had reversion so bad, the intake valve stems were so carboned up, they were blocking almost half the port- and the car only had 2 years running time on the street- there was black carbon up into the intake ports from it too
Zedo is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Port Volumes vs. cfm Gach Engine Tech Discussion - Street or Strip 128 01-27-10 12:26PM
Aftermarket Cylinder head stack ranking discussion Bruce Wilkie Engine Tech Discussion - Street or Strip 119 12-15-08 01:51PM
Flow bench variations gtofreek Engine Tech Discussion - Street or Strip 42 11-26-08 01:02AM
FLOW BENCH FALACIES....By David Reher JMackPontiac Engine Tech Discussion - Street or Strip 5 06-18-08 12:20AM
flow comparison KRE heads Rockin462 Engine Tech Discussion - Street or Strip 12 02-19-08 07:07PM


All times are GMT -3. The time now is 12:32PM.

Featured Ads
Ken's Speed & Machine
Mayhem Turbocharging

Carter Cryogenics.  What can we freeze for you?

Pacific Performance Racing

Central Virginia Machine Service.  Home of the Injun Engine!

All Pontiac Engine Kits

Larry's Auto Machine.  Full serivce auto, marine machine shop, domestic and foreign.

Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
2001 - 2007 PontiacZone.com
Page generated in 0.24765 seconds with 38 queries