fiesh27

Can anyone tell me the difference between an LT1 and an LT4 intake manifold? I am looking for something that will bring in more air but I cant find intake manifolds that are bigger than 52mm. Can anyone help?

fiesh27

Or what intake manifold would be best to put on?

97FormulaWS-6

The LT4 manifold was powdercoated red and had larger openings to the heads. (If I remember correctly).

Both the manifolds have 52mm TB openings stock, but it is very common to machine them open to 58mm or to a mono-blade style. (This can be done either at a machine shop; or at home with a die-grinder)

Either the LT1 or LT4 intakes are good pieces and flow plenty well for most applications.

Just open the TB bores to 58mm for aftermarket TBs.

If you're upgrading the heads then you may want to look into porting the intake manifold and gasket matching it to the heads.

fiesh27

Alright. Well I still have the stock Intake Manifold and TB. Would you suggest boring the manifold out to 58mm? Then getting a 58mm TB?

97FormulaWS-6

You can; it'll gain some HP (up to 10hp give or take from everything I've read).

The larger TB will see more gains/usefullness if the heads/cam is upgraded to use that additional airflow.

shoebox

A 58mm TB is often not needed. You might be surprised. There was a recent thread discussing this. You might search for it.

BTW, what is the "Airflow Booster" in your sig?

fiesh27

Cool......One more thing. You seem to know your stuff. What would you do to up the horsepower and torque on my LT1? With in 500 bucks.

fiesh27

An air flow booster is a piece that goes between the ports in the TB to help the flow of air into the Intake Manifold. It was only about a 5 hp gain, but gave me better throttle response. http://www.lmperformance.com/1814/2.html look at that website.

97FormulaWS-6

I know some; Shoebox there is one of the "LTx gods" around here :P

For $500; my personal suggestion would be a CC305 or 503 Camshaft, a set of 1.6 roller rockers, and a mail-order tune for your PCM. That'll be close to that price point.

shoebox

Commonly called an air foil. I thought it might be something else. If it gave you 5 HP I would be shocked.

fiesh27

What is a "mail-order tune"? It may be a stupid question. Just trying to learn.

fiesh27

And it honestly did give me about that much.

97FormulaWS-6

A Mail order tune is where you remove the PCM (computer) from your car and mail it off to be "tuned". "Tuning" a PCM typically happens on a dyno and is where the PCM is reprogrammed for the modifications done to the car to get it to run properly and at it's peak performance. With smaller/milder modifications like this; a mail-order tune is done by the programmers experience with the car and the modification done to know how to adjust the computer's settings. This typically yields very good results for mildly modified cars.

edit- This isn't needed with something like a TB change or Cold-air intake. But something like a Cam change, or cylinder heads, etc.

shoebox

You saw that on a dyno? You can't measure HP any other way.

fiesh27

Yes sir. Thank for the "Tune" help!!