First of all I want to say Hi to all of you. I'm a long time reader of this forum. And I read all the post I could find in LT1 section, but I hope you can help me with laying out the parts for my small project. I got a 1994 Z28 with LT1 that runs great - hes got 80K miles. This winter I'm switching my stock headers and exhaust for something better that will let my engine breathe a bit more. So this things will be done before the spring. I want to plan out a 3 step process for my engine.

First I want to make 383 out of my LT1 - that will put out something around 350 HP. Budget for this is around $5K with all the fabrication and work needed. This is going to be done around summer I hope.

Phase 2 will be with some more hard bottom of the engine redo - to pump up around 450 HP. So the stock tranny wont do it this time.

The final thing will be adding a turbo to the system so the engine will need to be rebuild again to lower the compression etc.

Since I'm not all that familiar with engines and modding I ask for some help with entire battleplan for making it work. What parts to buy, thinking of the next phase so I will have to use most of the last phase parts etc.

One thing - this car is supposed to be drivable on the street.

Thanks in advance.
Paul

 

IMO, i'd put the money in the bottom end the first time so you don't end up buying parts over and over. Forged would be a good bet, with low compression pistons. I would then get the best heads I could afford. Then later down the road, swap cams and add the turbo. I really can't justify changing things 3 times to get what I want. just my 2 cents

 

Problem is, dont you need low comp. to add boost? Won't the motor be a complete dog if he has lets say 8.5:1 CR without any boost? I would think he would need a bigger set of CC heads to drop the comp as larger gaskets arn't the best way to drop the comp that many points, and then change the cam of course.

 

Thanks for the reply, yes I need lower comp - that is why I will change some parts to do that. And Im prepared to do that. I divided that in 3 parts since I cant get that kind of money to do it in one shot.

So you suggest that I should switch the order - do the bottom end first and add stroker in the 2nd part.
Any packages you would suggest ?? with 3-4K for parts budget.

 

Sounds to me like despite your reading you still do not understand power is in heads MUCH moreso than displacement.

 

If I listen to your goals and not your plan, this is what I would suggest...

You say you are already installing exhaust so I will leave that out of the $5k

to make 350rwhp you do not need to build a 383...all it takes is a mid size cam and the supporting bolt ons....at this point spend as much of your cash on building the platform to support the power you are going to make down the road.

A turbo's 383 can easily make 6-800 hp depending on how aggressive you wan to be. That will take a very strong drivetrain and a well thought out suspension.

You should be able to do the cam swap for $1-1200 paying someone else to install. Then I would get LCA's, TQ arm, subframes, Panhard, QA1 Adjustible shocks, Springs, etc...money permtting...alot of those Items you can install your self.

At this point you should have the suspension to support the turbo motor...now on to the drivetrain. Time for an upgraded rear, 12 bolt, 9", ETC, then a transmission, I would suggest a TH400, or if you have to keep overdrive a 4L80E, but I have yet to see an OD unit survive behind a high HP application without often freshening. TO hit the 450 HP goal, you will need a good set of heads and a built bottom end....buy the heads according to the turbo plan...something like the AFR 210 or 227's with a good port job and an aggressive hydraulic roller on top of a high compression fully forged 383 will easily make 450+...buy the crank, rods and have the machine work done to support 800+ HP....this will be a good combo to hold you over until the turbo....for more power while saving for the turbo builsd you can always add nitrous.

At this point you can change the piston to lower the compression and freshen the motor up with new bearing all the way around and a new FI Cam grind....install the turbo (T76 or bigger ) aftermarket engine management change rear gear ratio and go run low 9's or even faster

going fast only takes money....how fast do you want to go

 

Here's my take on it. You can build the engine only 1 time and not lose much performance. Everyone likes to make a big deal about low compression and turbo cams killing the NA performance, but it simply isn't that dramatic of a difference. Build it the first time with 8.5/1 compression. You give up about 10% power versus 10.5/1, so on a typical 450 hp build, it will make 405 hp which isn't exaclty a slug. Now, use a "turbo cam" and it might lose nothing, or 5 hp max. So, you live with 50 hp less for a little while, but still have a respectable car. This might be a reasonable plan of attack:

1. A stout heads/cam combo, using a boost-friendly cam, on the stock bottom-end. For instance, a set of the new AFR 210 Eliminator heads (when they are released), an Edelbrock LT4 intake, and a hydraulic cam somewhere around 224/230-112. This would make something like 370 rwhp.

2. Build a 383 bottom end using low-compression and all forged parts. Install this with the existing cam/heads/intake. The reduction in compression ratio will be offset by the increase in cubic inches. Expect it to be within 10 rwhp of the previous combo.

3. Add boost.

This way, you only pull the engine once, and you only buy each part one time. And 370 rwhp isn't a slouch by any means.

Mike

 

Thanks for all your ideas, Since I'm not that familiar with all of that I need some time to digest all that info.

The idea with building engine 1 time is good but as we all know the suspension needs to be rebuild. And I don't think I can squeeze it in that $5K budget.

What heads and camshaft would you suggest to go with then ? AFR 210 Eliminator heads ?

I cant go over 5K in first phase so maybe it is really better to focus more cash on the suspension itself.

 

You will get alot of opinions here. Many people will recommend AI or LE ported stock heads. The AI's seem to be good, but I'm not sure about LE's stuff. You pretty much can't go wrong with a set of AFR 210's and new Eliminators seem to be very stout pieces. AFR's offer the advantage of a thicker deck surface which will seal better under boost, and also the option of larger chambers to lower the compression ratio.

For the cam, again, you'll get alot of opinions here but you can't go wrong with a 224/230-112 or 224/236-114 regardless of whether you're naturally aspirated, supercharged, turbocharged, or nitrous'd. Be sure to use the Comp Extreme lobe 3192 on the intake for .605" lift.

Mike

 

this is interesting, lets see the thoughts keep rolling.

 

I've got a 379ci, custom cam, 8.7:1 CR and the s/c is not hooked up yet. Engine performs well despite the CR.