lt1 intake

[lt1maro]

I am currently dealing with the fact that i have to fix the dreaded intake manifold oil leak, however i was wondering since i am going to have the manifold off, i was thinking of getting the interior of the manifold ported and polished for the 58mm throttle body i have coming. What i want to know is what type of gains can i expect with the throttle body and a ported and polished manifold and also how much the job will cost. Also will i have to switch the stock injectors with the increased air flow.

[Injuneer]

The LT1 intake flows fine just the way it is. A 58mm TB is overkill, with the mods you show. I've seen dyno results indicating a loss of 10HP with a 58mm on a stock engine. I've pushed 500HP through my 58mm TB, and air flow pretty much max'd out at 77% throttle blade opening (= approx. the flow area of a 52mm TB).

The stock injectors are good for 400HP.... you aren't close.

[lt1maro]

Thanks broh. However since i cant get a gain from the intake, what is the next step to take in modification. I want to run as close to a 12 sec. et as possilble.

[wako29]

Originally posted by lt1maro
Thanks broh. However since i cant get a gain from the intake, what is the next step to take in modification. I want to run as close to a 12 sec. et as possilble.

well, I am assuming you don't want to mess with engine components on this one (i.e. heads etc.), so I can only think of tinkering with the electronics a little. I have not gotten into the LT1 electronics yet (I have to get my TPI done before I work on my LT1, and the TPI is a WHOLE different animal in the electronics division), but I would assume you can get it modded fairly easily. Like I said, I am inexperienced in this area, but maybe one of those Hypertech modules (or something similar)?

[fastTa]

Put a airfoil in your throttle body, and switch to a 1.6 rocker. Those two will get you about 22-25 hp. I saw a 21 hp increase on the dyno with just the addition of a 1.6 RR on a bone stock LT1! I have an API airfoil I will sell for $15 plus shiiping. Let me know.

But like Fred said you shouldn't need to touch your LT1 intake (yet) and you don't need a larger TB yet.

[lt1maro]

What about a cam?

[wako29]

Originally posted by fastTA
Put a airfoil in your throttle body, and switch to a 1.6 rocker. Those two will get you about 22-25 hp. I saw a 21 hp increase on the dyno with just the addition of a 1.6 RR on a bone stock LT1! I have an API airfoil I will sell for $15 plus shiiping. Let me know.

But like Fred said you shouldn't need to touch your LT1 intake (yet) and you don't need a larger TB yet.

I have heard that airfoils don't work at all. This info is from the TPI forums, and everyone who bought one said they didn't notice a change at all in neither hp nor throttle response or anything else for that matter. Just an FYI.

Yea, rockers are a pretty good upgrade. I might suggest to just go to the LT4 hot cam package if you wanna do all that. It's a pretty good buy for everything you get IMHO......

[Mirroredshades]

Where did you get the 1.6 rocker kit. I am wanting to do this. How much was it?

[fastTa]

Originally posted by wako29
I have heard that airfoils don't work at all. This info is from the TPI forums, and everyone who bought one said they didn't notice a change at all in neither hp nor throttle response or anything else for that matter. Just an FYI.

Yea, rockers are a pretty good upgrade. I might suggest to just go to the LT4 hot cam package if you wanna do all that. It's a pretty good buy for everything you get IMHO......

It really depends alot on whether or not you have headers, and a Ram Air or cold air kit. The airfoil has been proven to increase cfm. Whether or not your motor could use the cfm depends alot on if you have headers and /or properly flowing and tuned exhaust system.

http://dtcc.cz28.com/flow/

I have seen a 1-3 even a 4 hp freak gain w/ the addition of an air foil.

I guess if nothing else it won't hurt and has been said to at least make the upper rpm throttle response slightly better.

I guess this could just be classified as one of those "BUDGET ON A BUDGET" type mods.

[Joe 1320]

I can vouch for the fact that some airfoils cause a HP loss, some produce a gain. I do know that one design that actually works is the type that completely covers the end of the TB, not the model that simply bolts to the center of the TB. For what it's worth anyway.......

[PhantomZ28]

he yeall,
i'm also thinking i should fix the lt1 leak son. is it really hard? how long do you think it would take? i'm just really nervous about takeing my engine half apart

[FireFinder20]

The LT1 intake is a breeze to remove. I did it in a few hours one Saturday aftenoon out of sheer boredom. I found it helpful to remove the bumper cover, just to get closer to the action. Just watch the fuel rails, make sure you release teh pressure before fooling aorund with them I wish I could give you a step by step, but it was a few years ago and I don't want to guide you the wrong way. Might I suggest picking up a shop manual to make your life easier?

Just my .02

[Kevin - Blown 95 TA]

If lt1maro already has a new 58 mm throttle body on the way, he could just put it on and see what happens - but as was mentioned, the car can't use the extra flow. Otherwise just return it and spend the $300 on something else like the rocker arms which WILL give a nice gain - adds about .030 lift and seems like a mild cam upgrade with the added reduction in temperatures due to less friction & more precise thaqn stamped units, adds to the tune. He does have a M6, however, so there's no issues that the 58 normally has with the A4. An airfoil is useless with or without the 58 because aftermarket TBs are more contoured than the stockers anyway and usually have the shape of the airfoil built in and airfoils were known to help on TPI cars, but not on LT1s. As for porting the manifold, the larger holes are simple as are the ports, however doing the rest of the manifold is a challenge because you can't get to it very well. Some guys have cut them apart and welded them back together afterwards, others have gone the extrude-hone rout (very expensive). Again, the manifold wirks just fine as stock (it's shaped like a small tunnel ram) and you should spend your money in another area until you are running 9s and are looking for a bottleneck. One bad thing about the manifold is that it has the air rushing in the front and it has to make some abrupt turns to get into the first cylinders, otherwise than that - it's a pretty good manifold for high performance. My vote would be fix the intake leak, leave the manifold stock, return the TB & buy the 1.6 rockers - you won't be sorry.

[lt1maro]

thanks for the advice. I guess i will go with the 1.6 rockers. Arent those the same ones on the lt4 motor? Also, a friend of mine has been trying to convince me to get a bottle. Im not to sure of this because my engine has 150,000 miles on it. Anyone running a bottle with high mileage and if so what would i need in order to keep my pistons inside of my engine if i do spray?

[Injuneer]

I'm suprised Ken hasn't posted his link to the intake repair procedure... pretty much the "standard", and GM approved.

Ken C's Intake Manifold Oil Leak Repair

When you do the job, you don't even have to worry about the fuel rails... just remove the 4 bolts that hold them to the intake manifold, release the clamp that holds the two hard lines at the drivers/rear of the intake manifold, pull the rails up, injectors intact, and flip the rails, lines still connected up on the cowl/windhshield area.... saves some work and some mess. You might have to release the lines from the big plastic clamp that holds them to the throttle body linkage cover, but that's simple.