The '90 L98 does not have enough get up n go. It runs good and I don't want to screw that up. I've read a lot about bolt ons etc.. Do you get any real power or should I go with new gears?

 

My preference is engine & tranny mods. My current performance is in my sig and the mods are on my site. BTW, even with increased fuel pressure my trip mileage is up 1-2mpg over stock a year ago.

I won't be doing gears. I like cruzin at 75mph and tacking only 1400 or so RPM. Plus that 32-33mpg trip mileage is too sweet. I'll be running 12s with stock 2.59s.

 

Most bolt-ons you add will give you better performance and add HP.
I did mine in stages.
1. corsa exhaust, K&N, foil
2. Headers, chip, plug wires, plugs, throttle body, thermostat
3. 373 gears
The most noticable change in power came with modified gears from 259. but with each mod I noticed more performance. The headers and exhaust are great for sound. If I could only do one of the three I would again do number one first. They way I look at it this, I can be as fast as my wallet...
:lol: :crazy: :seeya

 

It has always been my opinion that you have to get the power to the road...no matter if you have an engine putting out 200 horsepower, or an engine with 350+ HP.
Picture this: 2 identical L98 Vettes, one with 3.07 gears...the other with 3.73's. Again, all things being equal...the guy with the gears should win every time...based on 1/4 mile time trials.
We all know the L98 puts out gobs of torque, (whether it be a stock Vette or a modified one), and in order for that torque to 'work' for us we need to transfer it to the rear wheels, which in turn puts that power to the road, where it means the most.
Therefore, my suggestion is to go for the gears first, and then work on the 'breathing' capabilities of your L98. A good place to start is to get yourself a set of Flow Master Mufflers, and either a performance Cat Converter, or modify yours (by hogging it out).
Depending on how far you intend to go with your modifications...you may want to start thinking about a set of headers...and then a performance chip.
Do not waste your money on a generic chip, but get one that is tailored to your Vette's drive train (based on the modifications you've completed).
You can obtain a chip from a company such as TPIS (www.tpis.com), and speaking of TPIS...are you familiar with their Insider Hints book? It costs $25, and is loaded with 'how to tips', and guidelines on exactly what you're trying to accomplish.
Good luck with your project, and have fun with it.

 

TPIS Insider Tips is nothing but a $25 sales pitch. Dyno sheets and HP gains are nebulous at best. If I could do it again, I would save the $25 for real mods on the car. Just watch what people have done here and what their results are. Look at Vic89 and 65Z01 and other member websites for good tips. Just my $.02.

 

heres soemthing to think about i've done some number crunching on how much effective ft-lbs you gain my changing gears, for example going from a 3.07 to 3.73 gear add's an effective 21% more ft-lbs on in my case about 65 ft-lbs worth of force. To figure this out you do the following formula

TotalTorque= (braketorque X tranny gear X rear gear) x (0.8) <- mechanical loss 20%

by figuring out your total wheel torque, with different rear gears you can get a gross ft-lbs difference and then using a little algebra you can work out what percentage of torque increase you'll gain. Take a l98 for example going from 3.07 to 3.73 will give the same effect as adding 73ft-lbs to the engine. The question then is, can you get 73 ft-lbs cheaper else where..not likely besides n20. You also have to consider your top speed. going from 3.07 to 3.73 will drop the top speed in OD to 160mph(if you have the power to get there) and expect to cruise around 65mph at 2200rpm

 

I've seen a lot suggestions here to do gears. Most of these have come from people with LT1 cars, not L98's. The L98 is not as conducive to gears as is the LT1. Most who have tried it (Beachbum, for example), have slowed in the 1/4 mile. 3.07 is about as low as you should go, unless the engine has been modified to run higher RPM's. By putting in lower gears, you are taking the L98 out of it's desired powerband sooner. Not a good thing. If you don't plan to race your car, I'm sure initial acceleration would improve....but our cars already have a hard time not spinning the tires, due to the good low end torque. Check around a bit, then make your decision.

Good luck with your mods. :cheers: