Hello All,
I'm a new member here...I've got a 1987 Daytona Shelby Z with the turbo II. I have had bad luck with my mini mopar since the day i bought it...beautiful body and interior for 450$ it only needed a turbo. So, I bought a turbo replacement...a little beefer than stock. The day i had the turbo installed, it blew the engine. Then, i bought the new engine. Then the car had a huge power loss...boosts in the 5psi range. The cat converter had a rattle so i went ahead and cut it out...ran it with the hole where it should have been for a week. It was boosting around 13psi. Now that i have a pipe in the cat.'s place, it only boosts about 7.5. And thats the max boost at around 3500rpm's and it holds it there until the redline. The timing has been played with. Right now its set at about 13.5-14. I'm not quite sure where the timing was when it was boosting at 13psi. I run only premium and it wont ping any higher timing mark. 14 was conservative considering the stock timing is only 12. Should i continue to play with the timing or should i be looking for something else? I am almost positive there are no leaks. The previous turbo's seals were very bad so practically straight oil was shot straight through the turbo. Could the muffler be clogged? I really don't know where to start. Any help would be beneficial. Thanks

 

Do you have the factory pcm in it, if so it isnt supposed to go over like 6 psi of boost. If you have an aftermarket pcm which allows for more boost, then it may be a vacuum line.Hope this helps.
-Mike

p.s- You can find out if the muffler is plugged just by puting your hand so the exhaust hits it, if it doesnt feel very powerful you may have a clog, lemme know what happens with that.

 

The Turbo II's stock PCM allows 7.5 PSI max. boost. The Mopar Performance Turbo II PCM bumps it up to 13-13.5 PSI max. boost.

 

Thanks, I replaced the muffler because of a rattle--and hoping it would fix the problem--(ceramic cat. converter pieces clogging the pipe and muffler) and i'm boosting about 11 now...one thing though, the boost doesn't seem to fluxuate more past 4000rpm shouldn't it build until its redline? The turbo also has a little more lag then it should. Maybe i'm just too picky lol. I think timing might be the issue when it comes to the boost climbing with rpm. Any pointers? Thanks for the help!!

 

If your turbo is very big, it will tend to be laggy, bigger turbos are that way.I would try putting the timing back to the way it was from factory and seeing what happens then.

 

the person that own my car before said it would boost about 12 to 13 psi and that was total stock. if you put a bigger trubo it is harder to get it to boost high unless you put a boost regulater on it or and adjustable wastegate. if you are using the stock wastegate there is probbaly the prolbem, i have read that the the stock wastegate is weak and when under boost it tends to be pushed open the the exhuast gas and not by the wastegate. resulting in lose of boost. or like most poeple would say it is a bad vacum line.

 

I never had any boost problems with my '88 Shelby Z and it had over 200,000+miles on it. If I were you I would have replaced the muffler with a straight pipe, a turbo is it's own silencer as well as the cat.

 

The stock boost is 12lbs at WOT. You are correct about the waste gate cans. The larger DIA. waste gate cans work far better because of the larger internal spring.

I would reset the timing back to 12deg's and recheck all of the intercooler hoses and take a look at the vacuum lines as well.

 

I replaced most of the vaccum lines yesterday. The vaccum line to the waste gate had a tiny crack in it but with the new hose results weren't better I was playing with the timing the other day and it boosted its stock boost mark at 4 degrees....better than the 10 lbs of boost where the timing is supposed to be. I'm really not sure what to do. Maybe a better wastegate?? Any one know where i can get one that would bolt right up? It doesn't make sense to me why it would boost more at 4 degrees than 12. I'm not sure if it is faster when the timing is at 4 but the boost is lower than at 12.

 

Are you sure the boost guage is correct. If you still using the factory unit it may be getting tired. Check the line to the guage also. If it's bad it would be just like a vacuum leak.

You can stil get the larger WG's from www.fwdperformance.com