Jump to content

1990 Grand Prix McLaren Turbo, Looking for some technical info


GHOSTOWLGRID

Recommended Posts

Sorry if I do not have this posted in the correct section.

I am looking for some info and I can not seem to find it to easily.

The nice people at the grandprixforums.net said you would know better about this info.

 

1) What is the stock boots levels of the turbo LG5 engine?

2) What boost levels will the ECU kill the injectors and protect the engine?

3) The 4 SPD 4T60-HD transmission, is this what the 90 turbo grand prix McLaren came with? The transmission spline count says 35. I want to swap this into a chevy Beretta, the Beretta spline count is also 35, will the axles plug right in?

(I can do the modifications to mount the transmission, I just need the drive axles to be able to plug in.)

 

4) Where can I find a replacement turbo? (What is the ID number for the turbo to be identified with?).

6) What turbo is a good option as far as better response and higher boost capability? Will it bolt right to the existing flange?

7) Where can I find a replacement cross over pipe that the turbo bolts to? (I remember someone used to have one for sale for about 300 dollars and was all welded ready to go with flex sections as well).

 

8) Is the 4T60-HD transmission electronically controlled by the ECM in any way? (or is it cable controlled off the throttle like the 3T40 trans from GM? I'm assuming the TCC solenoid is the only electronic solenoid as far as shifting/driving is concerned?).

This is important as I do not have a book on the car, and I see a plug with about 6 wires on it, I need to know if it is electronic shift or not, I am hoping not.

 

I acquired a 90 gand prix McLaren, the thing is a pile of rust but the engine and transmission work great because they were maintained very well.

Link to comment
Share on other sites

1. peak boost in a stock calibration is 62.1kPa above calculated barometric pressure. that's 9PSI for reference, though keep in mind your dash guage operates off of guage values, not absolute pressure. if you were at a high altitude when you keyed-on(TGP code doesn't appear to update barometric pressure while the engine is running), you could see less than that.

 

2. with a stock calibration, the ECM will cutoff the injectors due to overboost at what looks like 166.5kPa absolute.

 

8. correct, no electronic controls other than the TCC solenoid. it's been a while since I've looked at it, but there are likely gear switches taking up a couple of those pins as well, these are used by the ECM to determine what gear the transmission is in for TCC scheduling.

Link to comment
Share on other sites

Matt Shantz sells rebuilt crossover pipes. GOT2BGM on this forum. There are a lot of options for upgraded turbos that are a direct bolt on.

Link to comment
Share on other sites

http://www.w-body.com/showthread.php/43001-Rebuilt-Turbo-Grand-Prix-exhaust-crossover-%28x-over%29-pipes-300-with-core-return

theres a link for crossover thread.

if you stick with a garret turbo most t25 and t28 will bolt on, however the stock turbo exhaust housing has the oxygen sensor bung build into it so if you were to change to a new turbo you would have to have a o2 sensor bung added to the downpipe somewhere. you would also have to change the oil and water line fitting but isn't a huge project. atpturbo.com sells garrett turbos and lots of other stuff needed to install them.

Link to comment
Share on other sites

http://www.w-body.com/showthread.php/43001-Rebuilt-Turbo-Grand-Prix-exhaust-crossover-%28x-over%29-pipes-300-with-core-return

theres a link for crossover thread.

if you stick with a garret turbo most t25 and t28 will bolt on, however the stock turbo exhaust housing has the oxygen sensor bung build into it so if you were to change to a new turbo you would have to have a o2 sensor bung added to the downpipe somewhere. you would also have to change the oil and water line fitting but isn't a huge project. atpturbo.com sells garrett turbos and lots of other stuff needed to install them.

 

 

Awesome! Thank you!

Link to comment
Share on other sites

1. peak boost in a stock calibration is 62.1kPa above calculated barometric pressure. that's 9PSI for reference, though keep in mind your dash guage operates off of guage values, not absolute pressure. if you were at a high altitude when you keyed-on(TGP code doesn't appear to update barometric pressure while the engine is running), you could see less than that.

 

2. with a stock calibration, the ECM will cutoff the injectors due to overboost at what looks like 166.5kPa absolute.

 

8. correct, no electronic controls other than the TCC solenoid. it's been a while since I've looked at it, but there are likely gear switches taking up a couple of those pins as well, these are used by the ECM to determine what gear the transmission is in for TCC scheduling.

 

Ok, What I am doing is installing the 90 turbo grand prix mclaren LG5 engine and 4T60-HD trans into a chevy Beretta.

That is why I was asking.

 

My plan is to (for now) plug the memcal (EPROM Chip) into the chevy beretta ECM, it will run everything just fine engine wise (Except the Boost solenoid), I am just skeptical on the transmission, it is a 4 speed, not a 3 speed.

 

In the beretta, it has TCC. Then for the gear switches: 2nd, and 3rd.

Well, the 4T60, it has TCC, then for gear switches, it looks to have: 2, 3, 4.

I will see if I can get away with just using 3 and 4 gear switches in the trans, then plugging them into the 2 and 3 inputs on the Beretta ECM. Then just going TCC to TCC.

Just enough to prevent the TCC from engaging when not in 4th for ovedrive D and when not in 3 for regular D.

(I am not sure yet, I bought the service books for the 90 Grand Prix, I will look over the wiring and what the books for both cars say to get an idea for this).

But this is my plan.

 

I am still considering using the 90 grand prix ECM. I have not decided yet.

Link to comment
Share on other sites

depending on what year/engine beretta you're coming from, you may have a 1227730(or a superseded version of it), in which case, it is functionally identical to the 1227727 that the TGP uses, just in a non-waterproof case and with a different connectors.

 

you'll want the gear switches hooked up, otherwise you may end up with a gear switch DTC and possibly a disabled TCC.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...