C_Rules

iTrader: (7)

If i get a 58mm throttle body for my LT1 do i have to do any mods to the manifold?

TAEnvy

iTrader: (2)

Yes you must have the Manifold ported to accept the throttle body. Well I think someone said you could bolt it up without porting but there would be no noticeable gains.

94strokedz

iTrader: (1)

You will need to grind the ports from 54mm to 58mm. I did it by holding the 58mm gasket to the manifold, then scribed the 58mm outlines, then I stuffed some rags in my intake to keep chips out, and started grinding with a dremel. Took about an hour. Then I vacuumed the chips out while removing the rags. If you bolt it on without opening up the holes you will create bad turbulence going into the intake, and will probably actually lose a little power.

C_Rules

iTrader: (7)

Lets say i do port the manifold to 58mm and get the throttle body will this effect my air/fuel ratio causing a problem because the engine is getting too much air? Especially is im still using the stock 24lb injectors?

MY99TAWS6

iTrader: (3)

Maybe on a full bore car not porting it will do something noticeable.I put my BBK 58 on recently and didn't port right now waiting to do heads ,cam and headers next springs and take intake off the car. I didn't notice anything at all in terms of big speed reduction. Car seems to run about same as before maybe a bit faster.I have a tazzo like a gtech to use for timing the car.
And the blades open normal,idle is fine..no bog if anything the car jumps too much off the line now but that might be as have my tps at around .78 and think its should be more like .50 to .65 or so.I will be tweaking the tps shortly ,its simple to do.

96capricemgr

iTrader: (1)

MAF will do a fair job of keeping fueling correct. Your question though indicated you have a lot of reading to do. Injectors should only be changed when they are maxed out or failing, not to change the fueling the engine is getting doing that is a good way to dilute the oil and blow the engine. New injectors REQUIRE reprogramming the pcm otherwise the pcm can grossly overfuel the engine washing down the cylinders and wiping out the bearings that is if moderate if severe enough it can detonate to death before it even gets that far. Injectors are not tuning tools.
With an A4 car a TB requires programming unless you want to blow up the tranny, the more power it will give at less throttle can cause issues because tranny functions at TPS scaled this is even when the TB results in no gain of overall power as it would in a stock car. 10% throttle angle with a 58mm is a whole lot more air than it was at that same percent with a 48mm.

Chris 96 WS6

iTrader: (1)

Is this an automatic car? If so you'll have to have the shift tables reflashed to compensate.

The reason is the trans shifts based on tps%,and since you'll get the same air at a lower throttle opening with a bigger tb, you get slower, sloppier shifts. It can kill the transmission.

This is even noticeable with a 52mm, but not as bad.

MY99TAWS6

iTrader: (3)

You don't need to tune the throttle body and never heard of a throttle body swap blowing up an auto tranny and been messing with these cars a long long time. You do of course have to tune the car if you change injectors.

96capricemgr

iTrader: (1)

Wether reflashing is needed with a 52mm might be debatable but saying it isn't needed with a 58mm is flat out wrong. A shift kit, pcm shift firmess tweaks or a vacuum modulator can all take care of this real issue. The pcm tweaks can offer a lot more gains that the others as far as power and drivability so that is the most recommended course.

Looking at your mods I see a Granatelli which tells me you buy first and research later though so maybe that is the source of your mistaken info.

Ed Wright

iTrader: (1)

Unless you are making more power than most guys, you certainly don't need a 58mm tb. I tested one on mine last summer, and gained absolutly nothing over a stocker bored to 52mm. Do the math. A 383" running 7300 rpm (the limit for the factory PCM) won't pump anywhere near 1000 cfm. Unless you have a bigger engine, making well over 500 hp at the wheels, don't throw your money away. Do, however, throw that MAF away. My 383" makes 508 at the wheels, through an unlocked 4400 rpm converter and 4.30 gears in a 12 bolt Moser, and it gained nothing. Unlike too much carburetor on an older car, a too-big tb won't slow you down, just cost money for no gain. If you have a 4L60E trans, like the others said, you will need the line pressure tables in the PCM shifted to maintain part throttle line pressure. Otherwise, good by clutches.

Good luck, Ed

96capricemgr

iTrader: (1)

From the fingers of the first LT1 tuning guru himself. Means a whole lot more from him than it does a dozen of the rest of us.

C_Rules

iTrader: (7)

I guess caprice and ed are the ones to go with. Only thing that sucks is that there are no LT1 tuners around here in NYC. Looks lke im gonna have to send the pcm to pcmtuneforless. Unless one of those power programmers will do the trick but im gonna have to read up them and find out what are all the things they can do. Also what size are the stock intake manifold openings?

96capricemgr

iTrader: (1)

DO NOT use a "power programmer" they cost more and do less than custom tuning you would be better off to drive down to pcmforless he is just over near Philly.
The stock intake openings are 54mm.

LTSpeed

So if I go to a 54mm do I need to mess with the PCM? I have a 4L60E and you said you had to change it if you go to 58mm, but what about 54mm?

96capricemgr

iTrader: (1)

With a 52mm it is best but some choose to tempt fate. A pcm reprogram is a much better early mod than a TB is anyway so do not try to put one off in favor of other mods.

Ed Wright

iTrader: (1)

If your car is as stock as indicated in your sig, you don't need a bigger throttle body at all. You will gain absolutly nothing. The stock MAF, throttle body & injectors are more than enough to support 400 hp at the wheels. There are much more productive places to spend your money.

Good luck, Ed

C_Rules

iTrader: (7)

im curious to know what should he spend his money on because im sort of in the same boat. i have my lt1 a4 bored out to 355, full exhaust, K&n fipk, trick flow intake elbow, msd ignition and no cats? im trying to go for an all motor car so what should my next upgrade be?

LTSpeed

I've got a number of things in the works to push it out to around 425-440rwhp, but I'm trying to figure out how all the upgrades balance out. If someone would publish a proven, cost effective, 430hp upgrade package for the LT1, I'd be all over it. As it is, I have to piece together little bits of info here and there to figure out what is the best bang for the buck. (Ex: Lloyd's LE2/3 h/c packages are a good start, but they're only part of the total picture.)

C_Rules

iTrader: (7)

LTSpeed im with you 100% on that one.