lt4 performance mods
 

I just bought my first vette, 96 lt4 and would like to make some performance mods ( not for racing , "just for fun" street driving). I don't want to sacrifice gas mileage, hope thats not having my cake and eating it too. I have new Eagle F1s and I have ordered cold air intake(3 K&Ns) and air foil and thinking about S/S exhaust and short throw shifter. I rode in one with flow masters and it was a little loud for my taste, have heard the CORSA is good (Any opinions?), What about chip or Programmer? Any info or opinions would be appreciated, like I said this is my first Vette so I know nothing.
Thanks in advance

The airfoild is only good as a paper weight. Corsa sounds pretty good, I just took off the mufflers and put in pipes, might be to loud for you if you didn't like the Flowmasters.
Programmers (Hypertech) are good if you change gears or want the fans to come on eariler for a 160* t-stat. For any real performace mods, you need custom programming. Such as from Ed Wright or http://teamzr1.com/tune.html. 96' is OBD II which does not use a chip, it has to be programmed. Other improvements can be done, gears (4.10) are a great help, cam, heads, headers. Suspension improvments like a Camber Brace, Cross Bar (www.r-dracing.com), 30mm solid front sway bar, poly bushings, etc.
And the 3 K&N "cold air" your getting, is not really a cold air intake system, it still draws air in from under the hood. There are only a few true cold air, like the one that uses the front licence plate area as an inlet for air.

It really depends on what your final direction or "goal" will be with the car.....Alot of people throw money at little bolt ons only to find them obsolete when they move or want more hp......I tell my cust. to write out there dream car on paper and then as money allows start building.....ask yourself questions like: Are you going to need the car as transportation??? How streetable does it need to be??? Are you a road course or drag course guy????? Power Adder???? These will help in the build up process to save money.....And make your selection of parts alot more fun to get together......Give me a ring if you want some more OPINION from me.......

410.213.0023

Kevin

I wish you would've posted here first before ordering some of those parts!!! I've not used the "Triple Filter" intake setup, or the TB airfoil. I'm generally not a fan of members who've never tried a product chiming in negatively about the gains (or lack thereof) from said part. However, I will just go as far to say that I've not read a single documented performance gain from either the 3 K&N's or the TB Airfoil.

The most popular "performance" mods for a newbie are usually exhuast (Corsa, B&B, Borla, Flowmaster, etc.) and gears (4.10s). There are many many many threads on both topics, so you should be able to search and find out all the info you want. I have the Corsas on my LT4 and absolutely love 'em - interior resonance was a big concern for me as well. Gears will probably be my next step, but I'm just holding out for a time when I can get 'em done. If you want a serious kick in the pants, consider long-tube headers (don't bother with shorties...your stock manifolds flow just as good). After that, you're looking at getting into heads/cam work, and that will change the "streetability" of your car, as well as how easily it will pass emmissions (if you have to worry about that in your state).

The best thing I can recommend, though, is to meet some local members, preferably those with an LT4, but any vette will do, really. Get to know them. Get to know their cars. When it comes to chosing an exhuast, there's nothing better than hearing it first-hand before going ahead with an expensive purchase and install.

All in all, you will find endless amounts of information here on CF. Just post any question you have, no matter how insignificant it may be, and we'll do our best to respond ASAP! This place is a 24-hr tech support hotline!!!

Before really getting into the engine I would recommend;
1. 4.09 gears, these really wake the car up and make 6th gear usable. I have them and still average 28+MPG on the highway.

2. Short-shifter, either the B&M or Hurst, I havge the B&M and love it, but I have never driven a Hurst...but everyone that has one seems loves it as well! The stock shifter feels like you're rowing a boat

3. Suspension, I upgraded the sway bars front and rear and installed heim joints to eliminate the body-roll. I then had the stock FE1 shocks revalved by Bilstein to firm up the ride a little, but still keep them compliant for daily-driver use. That combo really firmed up the ride without making it harsh in any way.

4. Brakes...the J55 brakes on the Lt4's are nice, but they simply do not compare to either a nice setup from Baer or the stock C5 brake system.

Getting more into the engine, you have lots of options.

1. I do exhaust first personally, the Corsa system is great...good sound at WOT and no resonence while driving. If you have the option (this all depends on emissions) I would also get a set of long-tube headers. Exotic Muscle makes one of the best sets on the market right now for the C4's

2. Top end...having the heads ported and swapping the cam can get you some serious gains. But this is expensive, and if you get a lumpy cam can also hurt drive-ability, but I think that's pretty rare. The stock LT4 castings are all you need for a 350 bottom-end, just have them ported and select a cam that compliments the heads and you can easily get 350-360+ RWHP.

See sig line for my mods. 363rwhp, 342 rwtq with excellent driveability and street manners. Stock was 300/300

Air Foil = Paperweight

Don't bother with custom tuning a basicially stock LT4. The OEM program is VERY good as delivered. Btw, there is no chip to replace in the '96 PCM. You have to have the PCM reflashed either by sending it out or purchasing software. The Hypertech Power Programmer tends to cost people power because it adds in too much timing advance.

I have a Hurst shifter and like it

Corsa is an excellent exhaust

Cold air intake is no better than taking tin snips to the factory air lid.

4.10s are fun :) Btw, for C4s you'll see 4.09, 4.10, and 4.11 rear gear sets. People are not typing incorrectly, there really is three different ratios. 4.09s are a hacked together aftermarket gear set based on an Isuzu truck gear set. 4.10s are manufactured to OEM specs by Dana for the Viper. 4.11s are an aftermarket gear set.

Lastly, buyer beware. What may work on an L98 or LT1 may not work on an LT4. The L98 is significantly different and the LT1 has subtle differences.

Good info from Jim..... :iagree:

You guys are amazing!!!!! Thanks so much! I am really enjoying this car so far, I think I got a pretty good deal on it( I have only had it a week now and I have put almost 1400 miles on it!). It is a Polo Green w/Tan leather, garage kept, bone stock with 15,300 miles on it when I bought last it Wednsday for $18,500. The original tires were hard as rocks, so hence the Eagles(big difference!). I am going to put it on a dyno before I add any mods and dyno it after the mods and see how it changes ( I'll let you know the results).
I have dreamed of owning a Vette every since I was 13 yrs. old and my neighbor took me for a ride in his brand new 1963 roadster. I just sold my business and have retired so I will have plenty of time to enjoy this beautiful machine.
Thanks again! :bigears

18.5k for a 15k mile car?!!? Man...you got a smokin' deal IMO. Way to go! Do let us know about the dyno results, as well. :cheers: :thumbs:

I first did a cat back system.....B&B....way too loud...no SOP, no dyno but maybe 10hp

I cut open my air box and used K&N....no SOP
I bought SLP triple snorkle...looks good....no sop

I did Hypertech & 160 stat.....no SOP

I did 4.10 gears....that was finally SOP especially in 1st gear

Car dynoed 295hp with above mods and still 26-28 mpg highway

So if one mod go with the 4.10 gears......cat backs are nice, but 10hp tops...

Enjoy your new car....LT4 is a great engine....

BTW I don't have but have driven a short throw shifter...GREAT mod..

You'll take most bolt on's back off (IMO)
 

I bought my first Vette about three months ago. Coming from the import tuner market I'm accustomed to getting significant increases from certain bolt ons. I've quickly found that not to be the case with a Corvette. I bought the car and ordered everything I could get from Ecklers and Mid America.

Air foil. Total waste. In fact they don't even stick inside the TB but rather clip into the air tube and don't properly seat unless you modify it to screw into the TB. Took out and threw in the trash. I have enough paper weights from my Z.

SLP triple filter open air intake (not CAI). I like it. It made a significant difference at top RPM's. Would do it again though only if they came out with a plastic version. I'm suspicious of the metal intake developing condensation inside when the AC has been on with the condenser sitting just below it. Potentially bad for the MAF.

Borla exhaust. A must have. Acceptable growl from inside. I like it loud.

Hypertech ODB-II tuner w/ 160 Thermostat. Hmmmm. The jury's still out on this one. Now it runs too cool. Won't get over 190. Must tweak fan settings.

Adjustable fuel pressure regulator. Don't touch unless you have money for new rings or can read what's actually going on and tune it properly.

QA1 adjustable shocks. No way. Will never touch them again. Don't be fooled by 'C-Series for Corvette'. They [may] fit a Corvette, they are not fitted 'to' Corvettes. What a shame.

Throttle bypass tubing. Still in the bag. Why bother.

No further mods planned. Will drive it until the next year C6 comes out then reap the benefits of GM tweaking the platform for me.

I started with the K&N, than got the B&B 3" triflo cat back system (I absolutely love the B&B, you have got to at least hear it before you buy anything) You should search for one of my previous threads asking about the B&B. One of the other Forum members was nice enough to post a sound clip of his B&B system.

My waterpump is going south, so I am in the process of getting a new one of those, and while the shop is at it, they are putting a new custom cam in also. I can't wait until it us done!!

BTW, my bone stock LT4 with 22K dynoed around 296-307 rwhp, with about 317-325 torque. Not bad bone stock!!!

Enjoy your car, the LT4 is a GREAT engine!!

:cheers:

If I was starting with a stock LT4, I would do full exhaust (Long Tube Headers, no cats), a Cam, bigger RR's, send the heads and intake off to a reputable shop and how them worked over, and maybe the varam intake if it ever comes out for our C4's. I would also do a short throw shifter.

Few things come to mind:

• Replace Air Filter / Install Cold Air Induction
• Pulley Swaps
• Performance Exhaust
• Performance Tune
• LT4 Supercharger lid replacement

Source: How to improve performance of LT4 supercharger engine

18year old thread, wrong car, wrong engine!