'83 944 V8 LT-1 swap

Hey guys, Just thought I'd give you all a formal hello. I've been roaming around for a little while now so I thought it was about time.

I'm planning on shoving a 1994 LT-1 (out of Z28) into my 1983 Porsche 944 here in a little while (trying to find a good machine shop for the engine right now). My initial goal is to start the pulling the 2.5 over Christmas break. I'm going to try and fab most of the parts for the swap myself or with the help of my dad. The only tool that we don't have right now that I need is a mill (hoping this will give us a good enough excuse to buy one). The car will be used as a weekend cruiser/street rod with occasional track use (mostly to just see what it'll do). I live right outside of Memphis, TN so I won't have to deal with all of the emissions crap.

Right now I'm trying to get all of my research done for the swap and will be asking a lot of questions as far as what parts are good to use and what has worked out well. I'm am trying to do this build on a somewhat limited budget, but will take the time and money to get it done right. For the moment I'll just be doing the engine swap and reinforcing the tranny to keep up for a little bit, then I'll get the brakes swapped and am thinking I'll go with the LS430 calipers for the front and turbos for the rear, but I've got to get some bigger rims before I can install those (I'm running with cookies right now).

Well, guess that's it for now.

Welcome! Should be a fun swap, those early bodies are light

We finished ours for $4000 including the car and could have done it a grand cheaper with a carb but we put a LT1 intake on a Small block Chevy and Megasquirt'ed it. People think LT1's are worth money up here for some reason. It's a great project and a blast to drive however I think my laptop geek (son) is going to continue pursuing his education rather than following in my skilled trade footsteps. He learnt a lot though.

Props on the budget. The knuckleheads at Rennlist keep coming up with 10-20k for a swap.

Depends on what you get, The LT's are less expensive than the 5.3 truck motor than the LS1 motor. I don't have that much into my swap, but I also was able to recoup a large amount by selling the turbo parts I didn't need.

If you don't have very many desirable turbo parts to sell to put money back into your budget and you get an LS1 and a few other goodies, along with not doing all the labor yourself, I can see those numbers being reasonable.

I could've saved some doing the swap myself, but it was worth every penny to have Eric to it IMO.

Doc, your swap would count as a budget swap as I have talked with Eric on what he charges and would send anyone to him because I wouldn't touch it for what he charges, plus he does quality work. I'm talking about the keyboard builders over on the Sh!tlist that don't have a friggin clue...

There's plenty of them over there that are a few sandwiches short of a picnic.

Alright. I've been trying to find out all the major parts I will be using before I get into this too much and I've got a couple of questions.

For the bellhousing. Will any small block Chevy bellhousing work? Or do I need to get the c5 bellhousing? If I get the sbc bellhousing what kind of slave cylinder/master cylinder setup will I need and what does the c5 housing require? (I think I'd like to use a HTOB just for simplicity). Will this work for a bellhousing?
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I'll have more questions about my clutch/flywheel setup later, but I'd like to get this stuff down for now.

That type of bellhousing would work with an adapter plate but that particular one would be difficult to use. It is a truck bellhousing and has a larger center hole. The truck bellhousing has a 5.0625" hole and the car has 4.625" hole. If you were to make an adapter you would need to make a ring to reduce the diameter to the car size. It is much easier just to get a car bellhousing.

That type of bellhousing would work with an adapter plate but that particular one would be difficult to use. It is a truck bellhousing and has a larger center hole. The truck bellhousing has a 5.0625" hole and the car has 4.625" hole. If you were to make an adapter you would need to make a ring to reduce the diameter to the car size. It is much easier just to get a car bellhousing.

I see. Why does the hole need to be 4.625"? Can I use the HTOB with this housing? I'm planning on pulling a bellhousing off a car at the local pull a part. Any certain car I should be looking for?

Thanks

If you use one of the factory HTOB's the hole will be too large with this bellhousing. You need th center everything and this hole is one of the things used for center.

There are HTOB's that normally bolt to the transmission (on some GM cars and trucks) that have a diameter to fit the smaller hole. Aftermarket types like the McMeod uses this as well and they also make a type to fit on the original bearing retainer that bolts onto the original GM trans. For this kind you need a bearing retainer and that indexes to the smaller hole as well. If you use the external slave cylinder you need a T/O bearing and that also requires a bearing retainer to support the T/O bearing.

Hey V8, what inner diameter is needed on a BH to get the largest LS clutch (12") with PP in there?

I don't know the dimension but the bellhousing that the 12" PP fits into is visibly different. I don't believe there is an OEM bellhousing that fits a 12" PP but has the small hole. The only two I am aware of is p/n 460486 and 6263756.

Here is a good site that has pictures:

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Just asking because the C5 2-pieces are getting scarce, Auto C5 BH's can't take the larger clutches as confirmed by Robstah. I have another BH that I will make 1 piece adapters for later. It has a 14.5" FW opening and is 6.375" deep. It is better than those Early 4 & 5" center hole BH's because it has a large 9.0" diameter concentric-to-pilot opening so the 944/968 TT flange can be inset in the adapter plate and it still be structurally solid. I may need a ginea pig...

Woah.... I thought Gregg physically confirmed that a 12" would fit the auto BH's. He even made drawings to illustrate. You guys are saying this is incorrect?

something's amiss...

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I'm actually stumped. The only thing I can think of if that the LS flywheel surfaces protrude out farther than the LT flywheels and maybe a 12" clutch on the LT will clear the Auto C5 BH whereas the LS FW with 12" clutch will not clear the Auto BH and Greg was right about it (12" clutch) fitting the Auto C5 BH and his LT?

I know the LS pilot adapter is 1.00" and the LT pilot adapter is 0.60" but not sure if that has to do with FW surfaces and ring gears lining up but crank end differences.

The LS does stick out further. GM Performance Parts makes a spacer to use the late automatic transmissions on the early engines (to space the trans further back because the bellhousing flange is further forward on the LS) so that is probably why the PP doesn't fit.

O.K. I think you had it backwards in the other post saying the LS flywheel is closer to the block. It all makes sense now. So this has to be in the Wiki.

This just opened up another can of worms because the 2 different alternative BH's I'm eyeing for a 944 adapter plate are (97-99 pre-LS 6.375" depth) and (99-up LS specific 7.00" depth). I wonder if that spacer you are talking about is this difference of 0.625"?

The thickness is something like that. I think I have the dim somewhere I'll have to look. The GM p/n is 19154766 for the adapter kit but it doesn't say the thickness in the catalog. The kit has the adapter, a flex plate, a bellhousing dust cover and hardware.

It is better than those Early 4 & 5" center hole BH's because it has a large 9.0" diameter concentric-to-pilot opening so the 944/968 TT flange can be inset in the adapter plate and it still be structurally solid.

Kind of sounds like a marine bellhousing I was eying on e-bay sometime ago. It was cast iron shaped something like the C5 auto but had a much larger hole.

Alright, I've been looking for someone to hot-tank my block and clean the heads and intake. I've called two different places and both have given me quotes of $100 for just the block! I've been searching online and most people say they've spent about half that for the block. What kind of prices have you guys been seeing? What did you end up doing to clean your engine?

Just an update.

I got in some new parts from summit. I ordered it on Wednesday and it was here by Friday (I just used ground shipping too). I ordered some long tube headers, a gasket kit, piston rings, all the bearings, and a clutch set.

I'll hopefully be able to start back up working on this after all my finals are done on Monday. We'll see what happens though.

Everything has been moving along at a fairly rapid pace (school slows it down a bit). I got the pistons dropped in, the front end sealed up, most of the seals on.

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Then I look in my number 4 cylinder and see a long deep scratch. So i pulled that piston to see what was going on. When I did I found this.

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So now what do I do? I've obviously got to re-hone that cylinder and get a new ring, but what if it make the cylinder too large? Then I'll have to totally take everything off and get it bored, then get all new pistons and such, which is a huge cost I wasn't planning on spending. What would have caused the ring to do that? When I installed it I was using a cheap ring compressor from autozone, it broke while tightening the number 5 piston (guess it was only made for a 4-cylinder car!), I then used a good quality one my dad had hidden back in the back of the shop. All the other cylinders look to be fine. Should I take out pistons 1-3 and install using the better quality compressor, or should I not since they're fine at the moment. Guess this is what I get for trying to build the engine myself. Any help or suggestions in appriciated. Check this out if you want to see more pics of the engine/car

Engine Photos

Car Photos

My best guess it to take it to a machine shop and have them look at it. I know how it feels man. You have one up on me though, you are running the old iron block, you can bore it out if needed.

Good luck man

Yeah, That's definitely good. I'm headed out now to hone it out and see what happens.