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Proven Engine Combinations Engine combinations, and the resultant HP and/or E.T.s

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Old 05-08-13, 09:48PM   #16
sprint250
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Finally, tjs44, someone asked the key question.

60' times? (diito)

weight & distribution?

rear tire type?
tire width & height?
trans ratios?
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Old 05-08-13, 10:26PM   #17
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Quote:
Originally Posted by sprint250 View Post
Finally, tjs44, someone asked the key question.

60' times? (diito)

weight & distribution?

rear tire type?
tire width & height?
trans ratios?
Agree to a certain extent,
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Old 05-08-13, 10:52PM   #18
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My 60 fter,s been consistant at 1.8, running drag radials 255/50/ 15,s, When im going thru traps car is still pulling hard.This yr. I changed monroe shocks on back to Comp. eng. 50/50 shocks. rear consists of adj. upper and lower a arms with air bags. Relocation bars on bottom. Set at bottom hole.Don,t know squat about automatic turbo gearing, what ever was from factory. Checked pinion angle -3 degree,s
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Old 05-09-13, 01:35PM   #19
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Saw you asking about converters, this might help you to kind of under stand how converters work. If you've ever had or driven or played with a 4 speed car this might click for you. With out dyno results it's a guessing game on where it makes peak torque and HP. Trial anderror that's why a 4 speed was easier to find those important facts.

Start with 4 speed. With a 4 speed you can adjust what rpms you leave the starting line at. If the rpms to high you smoke the tires and kills your ET, If the rpms are to low, the car kinds of blogs, spins the tires but then you lose that pined in the seat feeling. Then picks up again. That's because the rpms you left at are blow peak torque. The reverse happens if the rpms are above where you make peak torque. So a 4 speed is much easier to adjust to where it makes peak torque.

But the rear gear ratio has to be right even in a 4 speed. A 1.8....60 foot is a good indeication that something in your combination isn't right. I mean if your running a good tire it's obvious your not having a problem hooking the car up. You can play and adjust the rpm you leave at all day long and your ET is not going to improve.
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Old 05-09-13, 02:17PM   #20
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The right converter kind of does it for you, if the dyno says the motor made peak torque at 3800 rpms then the converter company will size it so it locks up at 4000 to 4200 rpms. So you leave at peak torque rpms. But the kicker is having the right rear gear ratio.

To figure out what gear ratio you need these are the factors you need to know, weight of the car, tire diameter, and what rpms the motor makes peak hp. Then the gear is size so you can go through the traps about 500 rpms above where the motor makes peak torque. If not the motor never reaches its full HP Potential. If the gearing is right then the converter will do its job. If its under gear then your spending money and playing with things that won't change anything as far as ET goes. Timing, jetting, isn't going to help.

In other words you could possibly have the right converter. But if the gear ratio is to high it won't allow the converter to Multiply the torque which will allow the motor to get to peak torque off the starting line, so no matter what you do, your ET's won't get any better.

A 70 Ram Air 1V judge comes with a 3:90 gear for a reason. Your runing a 3.70 gear. A 70 Ram Air IV makes peak HP at around 5800 rpms with a 3:90 gear goes through the traps at around 6200 rpms. That with a little old Ram 1V cam.
My guess is your cam is a little better then a Ram IV.

This why going by what guys say on a board is hit and miss, will more gear get you into the 12's yes if the converter is correct. My guess is your not reaching peak torque off the starting line. So your leaving a good .2-.3 tenth right on the starting line.

But, you also have to be making the HP. If your only making 350 HP and that care weighs 3700 lbs its not going to happen. So you really can't be help unless we know the weight of your car and the mph. What I'm trying to do is save you a ton of Aggravation, money, by making changes like a converter or rear gear change. Because at this point all anyone is doing is guessing trying to help you.
Get the car weighed and tell us the mph. Or at least tell us your mph. My guess is a 67 GTO weighs some where around 3500 to 3800 lbs.
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Old 05-09-13, 08:20PM   #21
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Got to be in that weight somewhere. My 67 when i stripped out all the factory interior was 3380
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Old 05-09-13, 11:11PM   #22
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Quote:
Originally Posted by Mr.Pontiac View Post
Inquired about my convertor, its 3200 to 3400 Continental
What they told you about the convertor is a generalized range. If you aren't making enough power it may be at 2800. If you are making a lot of power it could be 4000. Only way to tell is to test it. Do you have a manual valvebody in your transmission? One of the most important things to check is the rpm at which it falls back to after the shift. Check that next time you have the car out and let us know where you are on that.

As an example I have a convertor that when I first bought it stalled at 4800. Different engine with more power it went up to 5500. Same convertor with my new engine is at 6000. It's still not as fast as the convertor that's in the car now. It stalls at 6500 and I'm only shifting at 6800. The requirements for a convertor are also a little different for different transmissions. I wouldn't run one with that much stall in a th400.

If you're shifting the car at 6200 and if falls back on the shift to 3800 it will take it a long time to recover and build the rpm back up to the shift point again. You have to keep the engine in it's power band to get a fast et. That's why a car with a tight nitrous convertor is a dog when run normally aspirated. With the amount of power it's making without the nitrous it can't get up into it's powerband quick enough and stay there because of the tight convertor. Turn on the nitrous and it's up there in a heartbeat. It may be making 800hp normally aspirated but the et shows closer to 700.

It's all in the combination of convertor stall and rearend gearing to get the most out of the power you're making. Sometimes it's just trial and error. Usually a convertor company can get you pretty close as long as the info you give them is good. In the convertor department you get what you pay for. Off the shelf will be no where as good as one built for your combination.
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Old 05-10-13, 03:16AM   #23
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You can get lower 1st & 2nd ratios (planetary sets) for the Turbo 400 trans.
2.75 1st , 1.56 2nd will help a heavier car that is not high powered.
There are a whole host of differnt planetary sets available now.

Prices on these sets range depending on the severity of service the sets are designed for.
Prices start at around $700 and go up.

That's why the old 4 speed hydros from the 1950's and early 1960's were very popular in all the supercharged gas coupe & roadster classes for years because they had great gearing in 1/2/3 with 4 being 1:1
Guys were running over 700 horse through them with the the cars dipping ito the low 9's /high 8's.
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Old 05-11-13, 02:47PM   #24
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Mr Pontiac how you making out, get that thing in the 12's yet or are you still totally confuse. LOL
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Old 05-11-13, 04:46PM   #25
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Never confused, LOL, well most of the time anyways, Laid up for 2 weeks with a bad back, can,t fill left leg from knee down,Herniated disc between 3 & 4. Hang with me, can,t wait to get car out just not worth crap right now. I am being told to loose the 1 5/8 tube header and go to a 1 3/4. I just bought new headers for my new heads for next yr. Looking for a used set right now.
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Old 05-11-13, 06:09PM   #26
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What was the mph on those 13.20 runs you made. I get your car weighs 3500 lbs. hey rest that bad back. Go dig out those time slips and look up the mph.
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Old 05-11-13, 06:46PM   #27
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98 mph on runs
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Old 05-11-13, 07:15PM   #28
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If your car weighs 3500 lbs Your making 278-300 HP. Don't think that's enough to get in the 12's.
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Old 05-11-13, 11:44PM   #29
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everything i have in this motor that basically sucks big time!!
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Old 05-12-13, 12:09AM   #30
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Jesus Christ. I just look up the specs on that cam. Now I know why, that cam is .221/229 duration @ .50 that's basicly a Ram Air 3 cam. You need more cam. I'll bet that converter is stalling around 2800-3000 rpms. That's like the old Tri Power cam.
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