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1990 turbo grand prix help pleease


tgp1990

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Dang.  I was going to direct you to Gutless Supreme's TSTE Rebuild thread as there is a lot of good pics & info there pertaining to rebuilding the LG5, but I see all the pics are gone.

 

This is my personal opinion.  The LG5 has something of an issue burning up camshaft lobes (particularly #10) due to lack of oiling at startup and the fact that it does not use roller lifters.  While not usually an issue by itself, if you are going to go through the work of having anything machined, I think I would consider adding a new camshaft to the list of parts.  Of course at that point you are basically finishing your engine rebuild so it's a matter of how much you want to put into it.

 

I don't know much about the 3500, however it's a lot more work than just swapping engines. OBD1 and OBD2 are entirely different monsters.  I swapped a Series 2 3800 into my TGP and it took me hours/days of pouring over wiring diagrams and swapping connections to make it go.

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  • 3 weeks later...

I've decided to stick with the rebuild and I'm going to the cam while im in there. After taking a lot of the bottom off I got a cherrypicker and have now started taking everything apart to get the engine out.

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^ If in your position I think that I'd consider ditching the flat tappet cam in favour of the later 3.1 roller cam & lifter/pushrod assembly.

 

I could be wrong, but I don't think they are compatible.  You can use the 3100 rocker arms for a small HP boost (1 - 3?) but I believe that there was no way to make the roller cam/lifters work.

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I could be wrong, but I don't think they are compatible.  You can use the 3100 rocker arms for a small HP boost (1 - 3?) but I believe that there was no way to make the roller cam/lifters work.

I don't think so either.  But maybe he knows something we don't.  

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Got the engine pulled and found the actual problem. One bearing is completely spun and the connecting rod is wollowed out pretty bad. So, instead of rebuilding this entirely again right now we are going to do a 3500 swap since my buddy has a few around. Any comments or suggestions would be great.

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No, actually we are going to bring the turbo over and run about 10 lbs. It should hold no problem as long as I'm not ridiculous about it. It should also put out about 315-325 after the chip programming to run the 3500 as a 3100 just with more of everything haha.

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It's been a long while since I've researched this so someone correct me if I'm wrong.

 

Swapping in the 3500 can be likely be done, however I have no idea how you are going to mount the turbo to the 3500.  Do they make turbo kits for those?  The manifolds will be different. Probably would need high flow injectors to handle fueling under boost.  What are you planning for trans?  OBD II is going to want to control the trans, the 4T60 thats strapped to the LG5 I believe controls itself other than looking to ECM for TC lockup signal.  If swapping the trans than you need to worry about half-shafts, mounts, etc.  You WILL lose your DIC, as the OBD I and II use different data signals.

 

It isn't a project for the faint of heart.  Definitely do some research before even beginning this project.

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The 4T60HD runs off vacuum.  It's not computer controlled, except for the TCC as you mentioned.  The 3500 non-VVT can be run off a custom tune OBDI chip.  The turbo will likely require extensive custom exhaust work.  It's possible to use the LG5 headers and crossover pipe, but there may be throttle body interference there.   There is also a lot of wiring to be done, as well as getting an external crank trigger on there.  Bigger injectors are going to be recommended.  It's not for the faint of heart, but it's not out of reach, either.  It would be far easier and cheaper to fix the LG5, though.  

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Thanks a bunch guys heartbeat about took the words out of my mouth for how this process will happen. I'm wondering how the lg5 would be cheaper than the 3500. I'm getting a 3500 for around 250, then after the crank trigger, mounts, chip programming and some little things this shouldn't cost more than 600 from what I was told and have seen. The lg5 after the crank, rods& bearings, cam, heads machined and all the gaskets would run closer to 1000-1200

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Correct me if I'm getting the wrong impression,

 

you want to just use the 3500 block & bolt on the LH0 heads to continue to use the turbo?

 

the two sets of heads are entirely different where the intake & exhaust ports configuration is concerned, the old manifolds will not bolt to the new heads, but you can bolt on the old heads to the LX9 block,

 

as mentioned the crank trigger on the cranks are different, the 3500 trigger is a 56x wheel whereas the LH0 is a 7x wheel, 

 

Here are some links on 3500 swaps in place of the LA1 3400 engine & also into a Fiero and what was done to get the engine to work in a OBD1 environment.

 

If you wanted to...you could get a hold of Ryan Gick (Darth Fiero) over on the Pennocks forum, he's a wealth of knowledge on the various generations of the 60 degree V6 engine and custom setups, He's offered help  in the past on tuning on a couple of projects my son & I got involved with.

 

In the *thirdgen* link you'll see a couple of photos of the LX9 crank & what the trigger wheel looks like.

 

 

  http://www.thirdgen.org/forums/v6/578959-3-4l-3400-3500-a.html

 

http://www.megamanual.com/ms2/GM_DIS.htm

 

http://forum.britishv8.org/read.php?13,33762

 

http://www.fiero.nl/forum/Forum2/HTML/122271.html

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Thanks a bunch guys heartbeat about took the words out of my mouth for how this process will happen. I'm wondering how the lg5 would be cheaper than the 3500. I'm getting a 3500 for around 250, then after the crank trigger, mounts, chip programming and some little things this shouldn't cost more than 600 from what I was told and have seen. The lg5 after the crank, rods& bearings, cam, heads machined and all the gaskets would run closer to 1000-1200

I guess if you want to go all out on it.  All you'd need to do to make it run again is machine the crank and rod.  New bearings in the bottom end plus a gasket kit would run you about $100 - $150.  With the machining, you'd be around $300 - $400 range.  And it's a whole lot easier than a 3500 swap.  As noted above, you could only really use the 3500 short block with your LG5 top end and turbo setup.  To go full 3500 would cost way more than $600.  

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I am doing an entire 3500 swap. The 3500 I am getting is already setup for the turbo, the manifold from the 3.1 fits on the 3500. After the different crank trigger, mounts, chip programming, some throttle body work, and little stuff it should all match up fine. Thanks for the links. We do have a few of the odds and ends and the rest we are going to get at junkyards. What all do you see making it run over 600 by far if I get the turbo ready 3500?

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you're going to need to ditch the TGP logs for some good turbo headers long before the 600 mark.

He's talking about $600.  What manifold?  The TGP exhaust manifolds don't bolt up to a 3500, as I recall.  So you'd have to be running a different head on it.  

 

Just be prepared to spend double what you think it will cost.  That's generally how these things go.

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that makes more sense....

 

TGP logs will bolt onto 3500 heads so far the pattern is concerned(all OHV gen1-through to non-VVT 3500s use the same pattern), but the port size/shape are way off between a gen2 head and the 3500 port.... you could hog the TGP logs out to roughly the same size/shape, but it will only do so much.

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I seem to remember someone tried to make the ports match, but there wasn't enough material to port them and get them anywhere close.  I guess if they will bolt up you could use them, but they won't flow well.

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