I might be buying a Lt4 block from GM. Im wondering if all my accessories and parts will bolt right up to the block? I did notices that a LT4 harmonic balancer and the hub it goes on has different part #s than the one that is on my 95 LT1. Does a LT4 need a different balancer?

 

Exactly what are you looking to do? An Lt4 block will gain you nothing, an LT4 SHORTblock will gain you little, an LT4 LONGblock would be closer to worthwhile but still not. On the hub the LT4 was only ever OBD2 so there was a reluctor for the CPS pinned between the hub and timing gear, the LT4 would have had a shorter hub for that.

 

There is no such thing as an "LT4 block". The LT4 block was identical to the 4-bolt LT1 block used in the Corvettes, which is identical to the F-Body LT1 blocks, except for the 4-bolt mains. They all have the same casting number. If you are only buying a bare block, everything is totally interchangeable. Now, if you meant to say "short" block or "long" block, read the above post.

 

I know that just the block isn’t going to get me more power. I do know that it is a 4 bolt main. The block that I might buy is a short block. It has a 383 stroker kit in it with all forged parts installed. Im going to put it with my LT4 kit and ATI Procharger with 12-15 pounds of boost. I can buy it all BRAND NEW for 3000.00, what do you think. Just for the block on GM direct its 1700.00
I read something about the relocater for the CPS pinned between the hub and timing gear, what is a CPS?

 

It's a decent deal, now have you checked the compression ratio? CPS is Crank Position Sensor, it's only available with OBDII cars and it's used to measure misfire. You heard right, it fits between the crank sprocket and hub, timing cover must be removed if you want to get to the wheel.

 

Ok, I think the OBDII started in 96 right? I have a 95 (OBDI). I dont have the CPS on the crank. I have not asked this buy yet but do you think this crank would have it on? Can I just use my timing cover, hub and my bal. and not worry about the CPS?

 

OK...You can use your timing cover, and you can use your hub but you'll have to deal with the sprocket key, the key has to be flush with sprocket.
You can leave the cps wheel on but then you must use 96-97 hub, balancer is the same.

 

This whole thread is confusing. You were buying an LT4 shortblock from GM. That would imply that it has the LT4 crank, rods, pistons with "twisted" rings, etc. in it.... but now its a 383 stroker that you are buying, with a 4-bolt block and forged internals. You're going to put 12-15# of boost, AND an LT4 "kit" on it (seems very inconsistant to put an LT4 HOT cam on it, then add all that boost??).... as asked above, what is the compression ratio going to be? Are the pistons dished, because you certainly aren't going to want the CR you get when you put a stock LT4 (or are they already ported, and you didn't mention that also???) head on a flat piston.

 

It is a brand new Lt4 block from gm. I’m buying it from a privet party. The guy bought it from GM and had the stroker kit put in it, (6.2 liter bore, JE pistons, eagle forged crank and H beam rods. The compression is 9to1 good for blower set up. The only lt4 parts I don’t have are the lt4 heads. I have stock heads that have been ported and polished.
What do you mean its inconsistent to put a LT4 kit with a blower? (I had the kit before all the other stuff was put on.)

 

i think what he is saying is that putting an lt4 hotcam on this particular setup doesnt seem to be consistent with what your plans are for this block. why would you go with a whole new setup and not order a custom grind camshaft that would give you better power for your 383 forged block, ported heads with a blower?

one thing that is consistent... the amount of information that could have been useful in the first post that seems to be slowly trickling out.

 

The lt4 cam is 218/228 112 .525 .525 The guy that has the block also has a brand new comp cam for it, it is a 224/236 114 .502.520. I called my local dyno shop and they said that that comp cam isnt much better. What do you guys think? comp cam also has another cam that they say is for a stroker motor it is Comp Cams "Extreme" LT1 Camshaft, 236 / 242, .520 / .540 112 LSA, Very aggressive street/strip cam. Stroker engines, Heads, Headers, High Stall or M6, Gears, Computer Tuning Required. I still want the car to be some what streetable.

Where could I get a custom cam and how much?

 

How did the original buyer find "a brand new Lt4 block from gm." GM stopped making LT1 blocks (again, there are NO LT4 blocks... no such animal) in 1999, or maybe even 1998.

And now it turns out your "LT4 kit" is just a HOT cam.

The fact that it is an "LT4 block" seems to be a major mental block. You do not need LT4 parts..... e.g. damper, CPS, timing cover, etc..... because there are no LT4 parts in your engine except the camshaft. You need to use the CKP, matching timing cover and crank hub only if your LT1 engine had them, and a 95 does not have the CKP. You would simply reuse the hub from your 95.

Going to a larger displacement engine, and putting a huge amount of boost on it requires high flowing heads and cam. An LT4 HOT cam and even ported stock heads will strangle the setup. You may see 15# boost, but that's not going to come with a corresponding high air flow to the cylinders. A super charger is not about making boost alone, its about getting the flow AND the boost into the cylinders.
You will see 15# of boost, because of the huge pressure losses due to limited valve curtain area. You port LT1 heads so they flow better all across the lift range, and so they don't stall in the 0.500-0.650" valve lift range. Using a cam with only 0.535/0.525" lift on a ported head seems inconsistant. But.... hey... its your engine and you seem to have your mind made up, so go for it.

 

si, heres a good question for you. what is your actual plan for this car/engine? are you wanting to make this a horsepower monster that will occasionally see the road or do you want a semi reliable daily driver with some good power? sit down and write out what your complete goal is and then take some time and do some research on what its going to take to achieve these goals. so now you can build your engine around your goal and not around your block or supercharger. i'm not trying to insult your intelligence, its just that your questions and comments seem to be sporadic and seem to follow no guidelines with any type of consistency. point us in the direction that you want to go and maybe we can give a little bit better advice on how to get there.

 

I bought the car last summer with a fresh rebuilt motor. The guy put the car together with stock 4.00 TRW forged pistons, recondition rods and stock crank. He put the lt4 hot cam kit in with the lt4 intake. He then put the ATI procharger kit on with the 2-core intercooler set up running 7-8 PSI. I bought the car figuring that this is what I want ( a some what built lt1 with a supercharger).
About 2 months after I bought it I put the dam thing in the ditch. The intercooler got slammed in to the supercharger pulley and the harmonic balancer bending both of them and bending the end of the crank. Well now have to put the new crank in. I figured long as I have it apart I might as well put it back together stronger and better. That’s why I was looking at buying a 383-forged kit for it. That way Ill know that the lower end will hold what ever I put to it.
I found this so called lt4 block and 383 kit on camaroz28 4 sale for 3000.00. I figured it was a good deal for one it’s got a 4 bolt main and its got the good 383 kit it. My local machine shop says to make my stock 2 bolt main a 383 it would be 2700 to 2800$. That’s why I thought this would be a good deal $200 more and I have a 4-bolt main.
Right now I want a street able car some thing around 600 to 650 rwhp. I know that a bigger cam and better heads would help a lot. Right now I’m some what on a tight budget ( I wouldn’t be doing this 383 forged kit stuff right now if I didn’t have to). My local dyno shop guy said that my cam and stock ported heads would do the trick for now. I think he knows what he’s talking about he runs his car in the 9’s no bull. I figured next time the motor has to come out ill finish the job (heads and cam).
I never said I was some pro mechanic, that’s why I’m on hear asking you guys. I just got into this F-body thing. I’ve been more into my 87 G-body Turbo T (same as a Grand national). That was the first motor I ever built, I figured I did fairly good it made 489 hp and 497 foot p. at the rear wheels!
Ill ask the guy about the hole new lt4 block. I didn’t think the guy is full of ****. All the other stuff the guy sold every one has said good about him. He also said he would send it to machine shop so they can check it all out before I buy it.

 

I want to buy the LT4 intake manifold and the LT4 cylinder heads. If I bought these and went with the LE3 package from Lloyd, will I see a bigger performance increase if I had the stock LT1 ported etc. to the same specs? Is the LT4 "better" as far as being able to work on further such as what Lloyd can do to it? I like the looks of the LT4 intake manifold as well. If it's not worth it, I'll be getting my LT1 heads polished and ported to match my intake. Can I get the heads ported more than the LT1? Will I also need to buy alternative push rods *aside from the ones Lloyd recommended me for this LE3 setup* guidplates, rockers etc.?