LT1 Intake Manifold Removal/Swap

[lilredjeep91]

ok, i have a ported/polished lt1 intake manifold and 58mm tb im going to put on my car, my question is how long and how hard is it to do this ? is this something i am able to do in one night ?

[Camvill]

yeh its not very hard a couple of bolts and you are in i remember doing this when i blew a lifter.

[black95maro]

the vacuum hose diagram is your best friend. so is a service manual

[ar0ck]

That 58mm TB is going to hurt your car unless you need it to feed big cubes or forced induction.

Just be careful when re-setting the intake, that the gasket is correctly layed in the rear, because if you start clamping down on it and that gasket moves you'll be fighting a real nasty oil leak. Make sure you clean the edges really well as well from any thing that can prevent a perfect seal and properly torque the heads down to spec, thread by hand too because you'll strip the aluminum heads.

I wouldn't rush the project, plan for 2 days.

[sweetbmxrider]

silicone the china walls! the egr might give you some trouble, just be certain to be friendly with the silicone back there, the heat from the egr can cause a nice oil leak. its an easy swap though and i agree the 58mm throttle body is too much unless you are making 400+hp

[LTb1ow]

Can you prove that? Its not a carb so therefore you can't go "too" big. Isn't changing plenum volume, isn't changing runner length, so how exactly would a bigger TB hurt anything?

[Pampered-Z]

Can you prove that? Its not a carb so therefore you can't go "too" big. Isn't changing plenum volume, isn't changing runner length, so how exactly would a bigger TB hurt anything?


Because the opening allows more air at a given throttle opening you loss the proper metering of air entering the intake plenum, in addition, this larger opening can hurt air velocity at WOT. Just like putting a big carb on an engine that can't use the extra air flow, even if you go smaller jets. It is as important to have the proper velocity in the intake as it is proper volume and the shorter runners and flow of the LT1 heads need that for proper distribution and RPM range they operate at.

When I had heads, small cam ( Lingenfelter 211/219 cam) and shortie headers I was making 337 RWHP, At E-town I went from a 52 to 58 TB and lost 2 tenths. After 3 runs, I switched back to the 52 and the car picked right back up.


As far as changing the intake, not that hard. Only thing that could be tricky is you either disconnect the fuel lines, or unbolt the fuel rails and hold them out of the way. be careful not to damage the O-rings on the injectors too.

I always use the Felpro gaskets. Make sure you clean the block and intake very well. And as stated already, don't skimp on the RTV. I actually dimpeled my intake and block so the RTV can't push out or move.

[sweetbmxrider]

http://www.gmhightechperformance.com/tech/0902gmhtp_lt1_aluminum_rocker_arms_and_58mm_thrott le_body_upgrade/porting_edelbrock_intake_manifold.html

table at the bottom. avg hp hurts, peak does improve yes. that is with rr's though. i guess it leaves room for improvement if he does h/c

[lilredjeep91]

why would i be touching the heads ??? i never said anything about taking the heads off only the manifold, and i already talked to a shop and with my other mods its not going to hurt me since im going to be tuned but i want to know if anyone had a write up on how to remove and install the manifold.

[LTb1ow]

Its really not the hard, kinda self explanatory. Pull the TB cable, pull the fuel rail and injectors off, undo EGR tube in the back, assorted vaccum lines, unbolt TB, unbolt intake bolts, and voila.

[lilredjeep91]

thank you for your hello shownomercy, i just dont understand how the 58mm tb is going to hurt me since the car is going to be tuned for it and my other mods:-?:?:

[SuperSweet]

basically...if you dont have a bigger engine,cam,injectors etc...there is no need for a 58mmTB. Bigger isnt always better..you want to match your TB to your Heads/cam/intake needs. Being that you have the factory cam and heads(I assume), you just dont need this. Go with a 52mm

[Tru2Chevy]

Because your engine doesn't need the extra airflow of the 58mm TB, and therefor won't be using that extra air delivered by the 58mm TB, the intake velocity will be slowed. It's not really anything you can tune for.....the only time you'll need that larger TB is if you go big cubes or head / cam or FI.

- Justin

[LTb1ow]

But if you do end up with the 58mm on there, remeber to check/adjust your TPS voltage.

[lilredjeep91]

i understand what you are saying but when i took my car to TTP to get my trans done i told them about my manifold and tb and they said i will be fine as long as i get tuned so im going on there word, and i have no reason not to they did an awesome job with my trans,rear,and roller rockers

[ar0ck]

i understand what you are saying but when i took my car to TTP to get my trans done i told them about my manifold and tb and they said i will be fine as long as i get tuned so im going on there word, and i have no reason not to they did an awesome job with my trans,rear,and roller rockers

Well when you come back asking why your car is running slower then cars with similar set ups and stock TB's you'll know why. When was the last time TTP put out a really fast LT1 car? I'm willing to bed some people here also have as much if not more experience with LT1 cars.

[deadtrend1]

i understand what you are saying but when i took my car to TTP to get my trans done i told them about my manifold and tb and they said i will be fine as long as i get tuned so im going on there word, and i have no reason not to they did an awesome job with my trans,rear,and roller rockers

OK, what do we know. You obviously have it set in your head that you are going to do it even though you don't need it, so its useless.

GOOD LUCK with your setup.

[LTb1ow]

Also remeber to enlarge the TB opening to accept the new TB.

And what do you mean by p/p intake? Gasket matching stock heads will create a big area for air to slow down and then speed up, waste.

[sweetbmxrider]

hey if ttp sold the job, it must be solid.

[WildBillyT]

Will the 58mm throttle body work? Sure. Will it be optimal? Sounds like the answer to that is a resounding NO.