my uncle just came from indiana to visit and he came with his car..i was wondering if i race him before he leaves who would win..we have been arguing about who would win for a while now..

my 1992 trans am convertible 305 tpi with headers 3' downpipe and 3'magnaflow exhaust automatic

his 1989 chevy caprice 350 fuel injection its all stock but both are cars have around 100000 miles on the engine ... and we both have posi diff

who would win in a 1/4 mile race

 

I have a feeling he might have you off the line. hes got approx 190hp and 3.42 gearing with the same transmission. 0-60 might be close. Quarter mile you def have him beat. your at 200hp putting prob 160-170 down at the wheels with a 2.73 A/R. In 89' the caprice 350 was putting out 190hp with 700r4 and 3.42 axle ratio. He is prob putting some where between 145-160 at the wheels. His gearing is better than yours but your putting out a little more hp and you are around 500lbs lighter. I think you will win but it will def be a close race.

 

dang
we will see soon thanks

 

Your car has just about every advantage. What is your gearing? My 91 305 T/A dynoed 187hp/270tq bone stock.

 

Yea you do have just about every advantage but the axle ratio. I believe 92 trans am autos had a 2.73 ratio and Im not too sure how that would hold up against the caprices 3.42. The A/T LB9 like he has has a modest 200hp-285tq the manual LB9 has a more stout 230hp-300tq from the factory with 3.42 gears. The manual LB9 would eat the caprice with no problems. The auto should do it but its not going to be as easy both cars have over 100k on them. At that mileage you never know.

 

It doesn't matter, 500lbs is going to negate that gearing advantage pretty quick and he has full exhaust so he should be at least 200whp and the caprice will be around 165whp. Its not going to be a blowout victory, but he will start pulling away fairly obviously.

 

There is no way in hell that a full exhaust is going to give you 200whp from a stock number of 200 crank hp. Exhaust only frees up hp it most certainly doesn't add anything. The automatic 700r4 has at least a 12-15% decrease in power through the train. The 200hp number that Pontiac gave that motor 20 years ago was based at the crank with out an exhaust or restricted intake anyway. So at best with 100k and a FULL exhaust meaning with headers too and without cat you might be putting down 170-185 to the wheels at the MOST on a perfect day.

The same deal goes for the caprice this car may be putting down 145-160 tops on a perfect day.

I don't know about you but I have driven a 3.42, 3.73, and 4.10 on the track in the same car and by far at each step up in ratios there is a HUGE difference in 0-60 and 60' times. As well as top speed numbers.

Do I think the T/A will win. Yeah probably. It has a 500lb advantage and around 20whp. But I have never driven a 2.73 before so I couldn't say for sure. My money would be on the T/A but I wouldn't bet my life on it.

 

My 1991 Auto 5.0 tpi 700r4 with 2.73s and single cat (your "200hp" version, which btw is the same exact motor that is in the 230hp version) put down 187whp and 270tq. That means with drive train loss comes out to 230hp and over 300tq. Do a search on speed density (1990-1992) 5.0s, they are all the same. A 2nd cat and slightly larger exhaust piping are the only differences, but the motors are all the exact same. Do a


By freeing hp its adding. Full exhaust on a 5.0 tpi will add at least 20 wheel hp and as much torque. Do a

Again, my car put down 187wheel horespower and 270tq.



On a near stock motor with mild modifications, top speed decreases with shorter gears, especially 4.10s. Do a


we finally agree on something.

You have some reading to do.

 

A member of my shop told be a year ago when an l69 TA came into the shop that the difference between the hp on these models with the AT and MT was the cam grind. Which is the same on many cars today the cam grind and other small details are different between AT and MT cars from the factory. I should not have took his word for it I will search just because I am interested.

Freeing up is not adding. When I say adding I mean to the crank. You can "free up" hp with bolt on's to the wheels or in essence add hp to the wheels but you can only free up to what the factory spec is for that engine and maybe a tad bit more. This arguement comes up time and time again at the shop and is proven on the dyno.


Which is close to my estimate anyway. Also dynos sometime read higher/lower numbers that what you have depending on the type of dyno.

Yes correct stock builds with higher gears do decrease in top speed. I never said they didnt. Clearly I said There is a huge difference not once did I say your top speed increased or decreased. So it was not right to make that assumption. Gearing has a different percentage of an effect on all three of those. Believe me I do not need to search.

Yes.
As do you

 

That member isn't talking about SD TPI cars though. All speed density cars from 1990-1992 had the same cam and exhaust manifolds. My 1991 TA has the same cam as the OP's 1992 Trans Am and as some other guys 1990 IROC 5.7L.


He has more power to the wheels now with full exhaust than a stock car, can you at least agree on that?


It is close, but 700r4s don't have a 12-15% loss. More like 17-20%. My numbers on the DynoJet are typical on for a Lb9 auto in good running condition.



Again, you didn't say this below in your last post?


Take it easy, Im just razzing and trying to get a rise out of you in good fun. The OP, should beat the Caprice. Im going to see if my car is done at the shop.

Transamws6, sorry for mucking up your post. Go race your uncle and post results. Do a couple different races, from a roll and a stop.

 

What i was saying is I did not specify whether to speed increased or decreased. Obviously top speed decreases as you increase the gear ratio. Its basic physics.

Yes i agree wheel HP increases.

I thought drive-train loss on 700r4 was less. Thanks for the correction.

Im not razzed just posting my knowledge and what I think to be true from my experience. Thats what these forums are all about. Spilling knowledge and corrections for future and current reference. People can now benefit from out posting.

Yes I apologize as well for spewing over the thread with repetitive information. Hope we helped some. I wanna see the results. Be safe and have fun.