LT4 Best LT4 Mods

[db2]

Best Mods for LT4? Best HP for the buck?

Thanks
\db2
Carolina

 

[6 Shooter]

Intake, Exhaust, Headers and a Good PCM Tune - Git-R-Done! ​

​

Later . . . . . .
6 Shooter​

 

[db2]

On the PCM tune,who do you recommend?

\db2

 

[6 Shooter]

I'm pretty sure a few of the LT4 boys that's had it done will be on soon to let ya know...

 

[Louis Bartay]

LT4

On the PCM tune,who do you recommend?

\db2

www.pcmforless.com will get you close. But the best way is to have your Vette custom tuned and remapped on a Dyno. If your LT4 is stock, start with a open frame and K&N air filter. A 96 LT4 stock cat back is not too bad for a stock exhaust just replace the resonator with a X pipe and Magnaflow mufflers,or several others make 2 3/4 inch inlet mufflers to replace the stock ones. Now you have a 2 3/4 inch cat back that will out flow a after market 2 1/2 cat back for much less money. I wish I had know this before I installed a 2 1/2 inch Borla cat back on mine. But I still have my stock 2 3/4 exhaust for when I go 383 with the engine.

 

[Tuna]

PCM - I used www.fastchip.com out of Tulsa.

You might want to check www.grandsportregistry.com as there are lots of modified LT4 GS members there.

 

[stgry1]

A 96 LT4 stock cat back is not too bad for a stock exhaust just replace the resonator with a X pipe and Magnaflow mufflers,or several others make 2 3/4 inch inlet mufflers to replace the stock ones. I wish I had know this before I installed a 2 1/2 inch Borla cat back on mine.

I agree...I wish I would have done more research myself. I would have saved approx $700. I DO like the borla and the sound of it AND I will tell you it is definately lighter then the stock system so you save on weight...but still. I may have gone the other way.

 

[redvette6spd]

LT headers, Hot Cam, afpr, open air box, cat back, and a LT1 Edit Dyno Tune WILL put you over 400hp at the crank.

 

[Louis Bartay]

I agree...I wish I would have done more research myself. I would have saved approx $700. I DO like the borla and the sound of it AND I will tell you it is definately lighter then the stock system so you save on weight...but still. I may have gone the other way.

Ditto, but the 2 1/2 inch Borla Sounds sooo Good. And like you said our LT4 will not out flow the Borla cat back. But if we ever go 383 or something else (Super Charger) it's good by Borla. If I had the extra money with a 383 or 396 a B&B 3 inch might be the better way to go. And a set of Long Tube Headers. I am still going buy a X pipe from Racer70XX www.advancedautocc.com. for my stock 2 3/4 LT4 cat back. And see how it sounds with no resonator(X pipe) and stock mufflers.

 

[jonecap]

On the PCM tune,who do you recommend?

\db2

Take it to Jeff Creech at Carolina Auto Masters in Durham, NC for a dyno tune. He tuned mine and it runs like a scalded dog.

Also, an electric water pump is a great mod on LT4's. My et dropped 2 tenths in the 1/4 after adding one. 4.10's are probably the best single mod on a LT4.

 

[Louis Bartay]

Take it to Jeff Creech at Carolina Auto Masters in Durham, NC for a dyno tune. He tuned mine and it runs like a scalded dog.

Also, an electric water pump is a great mod on LT4's. My et dropped 2 tenths in the 1/4 after adding one. 4.10's are probably the best single mod on a LT4.

I agree on the 4.10 gears, as long as you have Drag Radials or Slicks. Our WS6 TA was slower as the stock tires would not hook up for daily driving.But with Slicks a Different Bird So I have just kept the 3.45 in my 96 LT4 Coupe. I doubt I will ever put slicks on it and take back to the Drag Strip. Just too hard on the ZF tranny and all the U-joints.

The water pump is a good for more HP, but I have read some posts about not being able to have them rebuilt. Not sure on that one. Dyno Tuning is a must after you are done with your mod's. Have Fun.

 

[Hrtbeat1]

I can't stress enough ... get a tune.

When I went from stock, to my LT headers/exhaust I lost 10 HP on the dyno. I was waaaayyyyy rich ... 11.5 A/F ratio. Plus without tuning out the rear O2's with most LT installs, the check engine light will always be on.

I've worked on mine some and got the fuel trims much closer. Haven't been back to the dyno but the butt-O-meter says its better now. Still have a little Optispark break-up at higher RPM's, gonna deal with that and the cam swap.

Gears

Any car will be more responsive to a gear change than any other mod.

 

[Vettelt193]

It's always best to figure out a plan.

Pick a budget and/or a performance goal before anything.

If your budget is $5000 total, you may wind up with a supercharger to achieve all your goals... BUT, if you start throwing parts at it before you figure out what you want, your budget could easily be gone before you know it and your outcome will be far less.

On the other hand, if you are just looking at the best gains for the money and aren't looking for anything specific...

Do exhaust (I like the muffler eliminators)
Open up the air filter lid (you can buy the frame, or just cut the old one off)
Get a K&N (or other good) filter

All that should total under $200 if you do it locally (i.e. have a shop cut your mufflers off and weld in straight pipe) With minor mods like that, you won't need a tune or anything else.

If you come up with a $$ amount, I am sure people here will give you plenty of things you can do with that amount that will yield vastly different results / driving characteristics etc.

 

[Boeingdriver]

www.pcmforless.com will get you close. But the best way is to have your Vette custom tuned and remapped on a Dyno. If your LT4 is stock, start with a open frame and K&N air filter. A 96 LT4 stock cat back is not too bad for a stock exhaust just replace the resonator with a X pipe and Magnaflow mufflers,or several others make 2 3/4 inch inlet mufflers to replace the stock ones. Now you have a 2 3/4 inch cat back that will out flow a after market 2 1/2 cat back for much less money. I wish I had know this before I installed a 2 1/2 inch Borla cat back on mine. But I still have my stock 2 3/4 exhaust for when I go 383 with the engine.

Louis.....just curious, why didn't you go to 383 when you had to rebuild?

 

[Louis Bartay]

I can't stress enough ... get a tune.

When I went from stock, to my LT headers/exhaust I lost 10 HP on the dyno. I was waaaayyyyy rich ... 11.5 A/F ratio. Plus without tuning out the rear O2's with most LT installs, the check engine light will always be on.

I've worked on mine some and got the fuel trims much closer. Haven't been back to the dyno but the butt-O-meter says its better now. Still have a little Optispark break-up at higher RPM's, gonna deal with that and the cam swap.

Gears

Any car will be more responsive to a gear change than any other mod.

Most LT1 are in need of a tune after any major mod's. I replaced the fuel pressure regulator(adjustable) on my LT1 TA and when I Lowered the PSI 5 PSI from the stock setting it ran better. I read on T.P.I.S. catalog that most LT1 are a little rich stock.

A gear change does Help as long as you can get traction. My 96 LT4 is a OBDII and every time I do anything major to it I have to have it remapped. Or the check engine light comes on :-(

 

[Louis Bartay]

Louis.....just curious, why didn't you go to 383 when you had to rebuild?

The clutch. It has a new Duel Mass Flywheel and OEM clutch installed about 3 months ago ( $2,000.00 parts and labor) and I was told that a 383 would need a Single Mass Flywheel. And I did not want to here the rocks in a bucket sound that the ZF 6 speed does when you do away with the DM Flywheel. My neighbor went with a Fidanza Aluminum Flywheel and a old style 11 inch pressure plate and it sounds terrible when he is in neutral and the clutch released. I was told After I had the new engine done that there is a 383 crank thatwill let you use a DM Flywheel. :-( As the 383 Eagle crank was about the same money.

 

[Hrtbeat1]

Most LT1 are in need of a tune after any major mod's. I replaced the fuel pressure regulator(adjustable) on my LT1 TA and when I Lowered the PSI 5 PSI from the stock setting it ran better. I read on T.P.I.S. catalog that most LT1 are a little rich stock.

A gear change does Help as long as you can get traction. My 96 LT4 is a OBDII and every time I do anything major to it I have to have it remapped. Or the check engine light comes on :-(

I agree with you Louis. I just looked back at the dyno sheet (I was able to plot out the past run with the LT header runs... the first runs were plotted vs MPH instead of RPM) and in stock form I was rich then too. Right around 12.5 AFR, with a little dip to 13 between 5200-5500, right where my suspected opti break-up is, not to mention peak HP. With the headers I was richer, right along the same curve, the dip gets to around 12.2 but the break-up is still there, for the most part I was around 11.5 AFR my peak HP was almost exactally 10 less being so rich.

I didn't use an AFPR just to see if the computer could adjust for the increased exhaust flow. Well actually I changed out the airbox also, went with the SLP claw. Either way I proved, at least to me, that the computer needs a little help. The hardest thing I've found is finding a data logger that will record the data I need. This being the first year of OBD2 its a little different, my current scanner does good ... except ... no knock retard. Kinda important if you ask me. I found that my STFT's were way rich (not a good thing when transitioning to WOT) I've got them back closer to zero now, still working on a few areas, but I'll have it worked out before the next trip to the dyno. Im gonna do another dyno session before I do my cam swap just to see where the tune is. Of course after the cam swap I'll have to do it all over again. That's the fun of it though right.

 

[JEFNLSA]

"Best LT4 mod?"

Without a doubt, 4.10 gears. Put some in last week and absolutely love 'em! Of all the mods I've done, this one raised the fun to drive factor the most...by far! Instant gratification mod....and for my car, makes all the other mods come together. If other LTx 6spd owners could sample/feel this mod, it would be the hottest one going. Whether on the highway or in town, the car is more responsive in every sense. Before the 4.10's, I used to rarely if ever even use 6th gear (too bogged down feeling for me), now it's the perfect highway cruising gear...70mph @ 2000 rpm. Hard to explain but it feels like the car just gained about 100hp because I'm always in the power band. The difference in acceleration is incredible & the short throw shifter just makes it that much more fun. If you have the opportunity to drive a 4.10 equipped C4 6spd, I highly recommend you do....IMO, this is the "Best bang for the buck LT4 mod"!!

Jeff

 

[BLACKTALON]

How whould a set of 373's in a A-4 compair to 410's in ZF-6?

 

[CAJUN C4]

Ditto, but the 2 1/2 inch Borla Sounds sooo Good. And like you said our LT4 will not out flow the Borla cat back. But if we ever go 383 or something else (Super Charger) it's good by Borla. If I had the extra money with a 383 or 396 a B&B 3 inch might be the better way to go. And a set of Long Tube Headers. I am still going buy a X pipe from Racer70XX www.advancedautocc.com. for my stock 2 3/4 LT4 cat back. And see how it sounds with no resonator(X pipe) and stock mufflers.

Mine is bone stock.What will the X-pipe do for it? Sound, Performance?

Thanx