C5 corvette: Gears/TC vs. Cylinder heads

My 97 corvette is running strong with 125K on the clock. I have all the bolt-ons i can get that actually do anything but i'm aching for m more bottom end power. The last dyno showed a farily consistant torque curve averaging 320 rwtq between 3.5 and 5K rpm.

This is a daily driver so reliability is a must. This means for the time being there will be no forced induction, cam or nitrous. I have 2 options on the table both of which are in a similar price range:

a) Upgraded gears/torque converter (~$1200 parts + labor)- My car came with a 2.73 diff. I'd like to swap out for the 3.15 factory option. Many C5 drivers with the 3.15 gears are upgrading to 3.42 gears leaving an abundance of 3.15 gears on the market (prices range between $300-400) A SILGHTLY higher stalll torque onverter would maintain drivability while letting me get a little more low speed power. GM makes a TC for their truck line that has been reported to do well in the C5 without making it completely unstreet-able. (prices range from $180-230)

Pros: SOTP meter says wow!
Cons: No real HP gains, 1-2mpg loss average.

b) Upgraded Cylnderheads/valvetrain (~$1500 parts + labor) The 243 head casting for LSX engines are a nice factory upgrade to the original LS1 heads. by themselves, I've seen reports of up to 30 rwhp and as a supporting modification up to 45rwhp. The heads would also recieve my existing 1.8 YT ultralite rockers and new Valvesprings and pushrods. Additional costs will probably include center-bolt valve covers, gaskets, coil relocation packs etc.

What do you think? A or B? (first)

Why don't you get a cam? I used to drive my Mustang like a DD w/ a cam and it was fine. If you have full bolt-ons then a cam should REALLY wake it up.

If you must choose from the two options, I would say option A. I wouldn't do head work w/out a new cam (or at least cam in the future plans). Gears are going to give you the most kick in the pants for the money.

I may consider a stealth cam in the future, but not right now.

btw: i like your sig.

Your pulleys have alot to do with potential torque, free up what you can. Underdrive what you need

If you just want more down low, I would just change out gears.

Support the gears with pulley mods

simply reboring your cylinders if you go with new heads can give you gains

The pulley sounds like a good idea since my harmonic balancer is undoubtedly on it's way out. I juet need to find one that underdrives the AC compressor as well....C5 corvettes have a seperate drive belt for that (do'h)

well you could also get a 383 LS1 storker kit for 2,000

JSewell wrote:

well you could also get a 383 LS1 storker kit for 2,000

aye, but i don't have the confidence in my block for that....or the cash for the labor required.

Bang for the buck,I'd definitely have to say gears for sure. When I had my Stang I swapped out the factory 2.73's in favor of some 3.73's and WOW! what a huge difference.

RF, i'd say you'd notice about a 15% increase in torque with your proposed gear swap

JSewell wrote:

RF, i'd say you'd notice about a 15% increase in torque with your proposed gear swap

Somebody can do basic gear calculations....3.15/2.73 = 1.1538

wow, i was just guessing

sweet, that would bring my torque curve up to the ~375 range

Here's a kicker for you, i was at the local Chevy dealership picking up parts. While waiting, I had the tech print up the build sheet on my car. Turns out I already had the 3.15 gears. The only reason i didn't think i had them was because my mom's 98 had a lot more pull low in the power band. The reason for this was the A/C compressor was shot and the parasitic power loss wasn't there. Once the A/C was fixed on her car, it went back to being slow off the line...lol.

It's time to start saving for H/C

Have you updated the computer chip?

Go with bigger gears.

Well now do you see what pulley mods can do for ya!

for lower end powr I would recommend a higher gear set...you will lose top speed but gain lower band power off the line....

If you are really serious about upgrading the power option on the car I would save for a supercharger and disregard all the rest at this time. Supercharger would really wake up the engine and would be safe for around 6-8lbs of boost.

Although this option would cost you quite a bit of money, it would be worth it in the end if you plan on keeping the car for awhile.

another option to think about.

I passed on the chip in favor of a full-on laptop tune.

I don't plan to keep this car forever so any type of forced induction isn't going to happen.....the next car on the other hand is a different story ;) (I'm thinking a Twin screw sitting on an LS2 should do it)

For now, i'm saving up for a Head/Cam swap. With the right equipment, this will net me the power i need where I want it without sacrificing street-manners....however it does come with a heafty price tag.

Radioflyer wrote:

I passed on the chip in favor of a full-on laptop tune. I don't plan to keep this car forever so any type of forced induction isn't going to happen.....the next car on the other hand is a different story ;) (I'm thinking a Twin screw sitting on an LS2 should do it) For now, i'm saving up for a Head/Cam swap. With the right equipment, this will net me the power i need where I want it without sacrificing street-manners....however it does come with a heafty price tag.

Find a friend and have them help you. I did new cam, springs, and port & polish the heads by myself for $800. $300 for a dyno tune and I had a who new setup for just over $1k. Don't get a canned tune after the cam either.

so your pouring money into the vette, when you plan on fully modding a new car?

JSewell wrote:

so your pouring money into the vette, when you plan on fully modding a new car?

I'm setting some paper (lol) aside for the new vehicle fund. I'm trying to decide between a Silverado SS (practical) or a 2010 camero SS (in about a year when GM goes to complete crap and people need to get rid of them)

my buddys dad has a Silverado SS, very very VERY beautiful

So you want a big rowing boat? Get the Silverado.