89 LM with 89 Swirl Head

[mimiGLH22]

Hey I am doing a conversion from t1 to t2 on my 85 Omni GLH. Because I purchased an 89 Swirl head off of a Shelby Z, do I have to use 89 electronics( LM for example)? Or can I go with an LM off of a GLHS(86-87)? I am more than likely going with a different bottom end because I was told of compression problems so......... any help in this situation would be greatly appreciated. Thanks.
-Chris

[Shel-Game]

The '89 cars use the SMEC (the logic board is in the same housing as the power board). You could swap your car over to SMEC electronics, but I think that's a bigger job than you want. I think the '87 T2 used a swirl head, right? So, you could just upgrade to '87 LM. There might be some wiring with that as well, I don't know for sure. Also, I'm pretty sure there are custom cals out there to run a swirl head on LM electronics.

[Phreakish]

you have an 85 omni - the problem is that it uses a G head (bathtub head) so putting a swirl head on it will increase compression!

and if you keep the G head (I'd recommend it for now) then the spark curve in the other computers doesn't work right either - its too retarded in the midrange

The 'solution' is to get a really good IC, run the T2 intake with turbo 2 injectors in 1&2 (the log computers leaned out 1&2 for the horribly flowing log) and run T1 injectors in 3&4, you'll max out at ~14 psi or less, but it'll make WAY more power than the log at 14psi or less - but you also have to advance the timing a bit until the mid range doesn't dog on you and watch the a/f and if you have a scanner keep an eye out for knock! use the highest grade gas you can find while tuning!

So, use your stock computer, keep your stock head but put the T2 manifolds on it, and then IC it with a decent IC (something better than a stocker, otherwise I wouldnt' go beyond 12 psi with only T1 injectors in 3&4).

The biggest problem is that since 1&2 run ~10% leaner, and T2 injectors are ~10% richer than the T1's - its a wash, but the T1 injectors can't support real high power. The good news is that once its all said and done, you can save the money you would have spent on pistons and other rebuild goodies (that would have been needed to use the swirl head) and get a custom cal and convert to a smec! Or learn Dcal and convert to a smec anyway - its not that much work and is a MUCH better computer!

This is what I plan to do with my '85 Charger - already got the manifolds ready to go, got an SRT-4 IC and just need to get me some 3" exhaust pipe and some new pipe to make the IC lines and away I go

[mimiGLH22]

Quote:

Originally Posted by Phreakish you have an 85 omni - the problem is that it uses a G head (bathtub head) so putting a swirl head on it will increase compression! and if you keep the G head (I'd recommend it for now) then the spark curve in the other computers doesn't work right either - its too retarded in the midrange The 'solution' is to get a really good IC, run the T2 intake with turbo 2 injectors in 1&2 (the log computers leaned out 1&2 for the horribly flowing log) and run T1 injectors in 3&4, you'll max out at ~14 psi or less, but it'll make WAY more power than the log at 14psi or less - but you also have to advance the timing a bit until the mid range doesn't dog on you and watch the a/f and if you have a scanner keep an eye out for knock! use the highest grade gas you can find while tuning! So, use your stock computer, keep your stock head but put the T2 manifolds on it, and then IC it with a decent IC (something better than a stocker, otherwise I wouldnt' go beyond 12 psi with only T1 injectors in 3&4). The biggest problem is that since 1&2 run ~10% leaner, and T2 injectors are ~10% richer than the T1's - its a wash, but the T1 injectors can't support real high power. The good news is that once its all said and done, you can save the money you would have spent on pistons and other rebuild goodies (that would have been needed to use the swirl head) and get a custom cal and convert to a smec! Or learn Dcal and convert to a smec anyway - its not that much work and is a MUCH better computer! This is what I plan to do with my '85 Charger - already got the manifolds ready to go, got an SRT-4 IC and just need to get me some 3" exhaust pipe and some new pipe to make the IC lines and away I go

Hey Phreakish, first I have heard some good things about you so I thank you for giving me imput, and second, my stock head went for a pressure test and they found two hair line cracks. So what I did was I found a head( not knowing it was a swirl) and purchased it because I needed a head asap. The good thing about this head is that it came with an aggressive cam and was pressure tested, which was great. I bought this head not knowing about compression problems. I talked to Cindy over at FWD and he said that it shouldn't be a problem using this head as long as I have a thick head gasket. He said for now it'll be ok, then later down the line upgrade the bottom end or just go ahead and purchase a 2.5 bottom end from someone for dirt cheap. With that said what do you think I should do? Thanks.

-Chris

[Phreakish]

if you use this head on your G head pistons... then you'd better keep the boost down while you run it or it could cause problems - or buy a set of T2 rods/pistons and have some REAL fun!

pistons aren't too expensive either, especially if you can find a used set - I'd do that instead of later going BACK into the engine to swap them AND have to get new bolts/gasket/etc - and the only 'thick' headgasket I think I've heard of is the cometic which is a bit pricey for a gasket...

[mimiGLH22]

Well I guess I will be junk yard shopping for t2 rod and piston combo. Thanks for the info, it helps alot.
-Chris