are 3.08's killing me?

[gbulldog7]

Need a little insight fellas. I recently completed a HCI swap on my '89 GT. Before I go any further, I want to explain that I was just looking to build a strong, reliable, economical (not according to my wife) daily driver. The car was completely stock when I started, and here are the mods I made. 1995 cobra GT40 irons (Crane 1.7 RR's, upgraded valve springs, and slightly bigger valves...intakes are 1.90, not sure about the exhaust), Trick Flow street heat intake upper and lower, Trick Flow stage 1 cam, 70MM BBK throttle body, BBK longtubes with matching off road x pipe, and a BBK cold air intake. I stuck with the factory 19lb injectors, and the stock mass air meter. I'm hoping that I'm making around 270-280 RWHP. The car feels stronger, but not to the degree that I expected. 1st and 2nd gear are really strong, but then it falls over when I shift into 3rd. The car runs smooth, with no obvious tuning issues. I know that I need an adjustable fuel pressure regulator, and it is in the works. The only noticeable difference/problem is that it smells like it's running pretty rich. My buddy is saying that the rear gears are killing it, and I'm inclined to agree. Keep in mind that I'm fairly new to this sort of thing, but I feel that I made fairly decent choices with the mods I made. I would like to have the car capable of low 13 second 1/4 mile times when it's all said and done. Thanks in advance for the help.
JC

 

[BlownFiveLiter]

Gears would absolutely help, but you could be running a bit lean and hurting performance there, too. You could probably avoid the AFPR, by stepping up to some 24lb injectors and matching MAF. A quick example, my 95 has the mods listed in my signature, but still the stock 3.08 gears and stock fuel system. I'm afraid to really wind it out, for fear that I'm going to detonate and wipe out my shortblock. 30lb injectors + MAF and gears are also in the works for me, too.

 

[Foxfan88]

the stock 19s can handle that combo just fine. the stock sized meter could be choking it off. grab a cheap C&L meter with the sampling tube for 19s, that what i used and it worked great.

as for the gears. they should help. but IMO gears are overrated. and ARE NOT the super duper sotp gain people make them out to be. what little sotp feel you do gain is all in trade off for higher cruising rpms = worse highway mpg. blasting through all 4 gears too fast and being done in 4th gear at like 115-120 etc.

dont get me wrong gears can really give a stock car a nice kick but once you start making some decent power like a healthy HCI or blower. the low gears hurt you more than that help at higher power levels. with more power you dont need the help of lower gears to get the car moving. my 3.90s worked great N/A but wheni added the blower, all it does it fry tires and each gear is gone in a flash. i am planning on swapping to 3.55s. some HIGH horsepower cars even run 3.27s

as for 2.73s those are TOO high of gears and are not good for anything but good highway MPG. i'd ditch them...

for a mostly street car, i'd get 3.55s or 3.73 MAX, anything more is silly IMO, unless your drag racing all the time and want to dial in the trap rpms to where your engine peaks horsepower etc.

just my two cents

 

[gbulldog7]

Thanks for the input, fellas. Does it sound to you guys like I have realistic expectations for the car? I'm going to upload some pics of it soon as I'm really proud of it. I had it repainted back in December when I was deployed, and I consider it to be one of the cleaner fox bodies in this area. Any other opinions and what can be done to further enhance the car?

 

[ttop88]

For your combo 19s are fine. If it smells rich check your plugs to confirm it is rich. You most likely need oxygen sensors because they are not doing there job.
Edit: Yes your gears are killing you. Grab a set of 3.73s and be happy with a better feel and better gas mileage.

 

[BigHairyMonkey]

i ran a 13.40 @ 101 w/ the STOCK heads,cam,& intake. you car should be a mid 12 car on a tire AT LEAST. Oh and i have 3.73s and i really couldnt see any more gear in my car.. im already shifting every 2 seconds lol

 

[Mr. Rustypwnz]

I had 3.08's in my 86gt with about the same combo, and it would flat own in 3rd, and 4th, mostly because I had nothing inside of it, and it smelled like gas as well, but again alot of crap was taken out..

 

[Foxfan88]

Thanks for the input, fellas. Does it sound to you guys like I have realistic expectations for the car? I'm going to upload some pics of it soon as I'm really proud of it. I had it repainted back in December when I was deployed, and I consider it to be one of the cleaner fox bodies in this area. Any other opinions and what can be done to further enhance the car?

yes i think you should be able to run mid-low 13s fairly easily assuming you get traction.

 

[67coupe]

Gears got me .3 sec and 3 mph in the 1/8th. Gas mileage went from 25 mpg interstate to 22-23 mpg. They are worth every penny. After the swap, I couldn't believe I waited that long to make the change.

Do it. Like everyone says..."Don't fear the gear."

 

[ninety15.0]

Gears are a must. While i agree that they are not the end all be all of mods. They do help HCI cars get into and stay in the power band. I noticed that my highway mileage didn't suffer that much at all. Maybe 1-2 mpg if i'm driving faster than 80mph. If i drive 75 mph... i get about the same mileage (22-25).

However i do not suggest you throwing a C&L meter on there. While there have been some people to have success with them. The majority of people wind up with some type of driveability problems...or rich/lean condition. Get a quality meter like a pro-m/pmass and you will be much happier.

 

[rd]

The 3.08s are not going to give you either good economy or good performance.

For some reason, either up to 3.73 or down to 2.73 seems to be the way to go.

 

[enyawix]

At the over 300 crank I bet he will make, I would go with 24lbs injectors giving him room to grow. A set of 3.55s would also be nice. That 70MM BBK throttle body may create low speed throttle control issues. I think it is a bit big for a daily driver 302.