[lr172]

I am planning a turbo conversion for my “new” ’88 3.2 Carrera. I have read many threads on this forum as I attempt to educate myself. I am a decent wrench and have experience rebuilding Chevy’s. I have begun planning and was hoping to get some guidance from the experts during my planning phase. I am not looking to go crazy, just some additional ponies to help the car reach it’s potential. I am planning to start with no intercooler and a boost of .5 bar. I would like to someday add an intercooler and bump the boost to .7. The car has 125K miles and has never had a rebuild. The PPI indicated strong compression (175-180) and reasonable leak down (6-8%). Based upon inspection, They indicated the valve guides have moderate wear and the head studs are intact. I plan to do a top end rebuild this winter or next. This is a street car and likely won’t see the track, although I could see myself doing DE’s.

I will be leaving the stock exhaust headers and will likely fabricate a J Pipe to feed the turbo. What size pipe is recommended here (2.5”?)

I have the opportunity to purchase a used turbo from a member here on the board. It is a Garrett T3/T4 (T04E) unit. The Specs are:

Hot: .63 AR, 76 trim
Cold: 60 AR, 60 Trim

Based upon what I learned from the Garret site about sizing, my application (350-400 HP) seems to fit well on the Compressor map for a street application, which is what I am looking for. I am willing to sacrifice a little top end pull in exchange for having the turbo come on early in the RPMs. I am looking for something that will both begin to boost early, as well as to produce a decent amount of it’s boost early in the RPM range, even if the engine flattens out a little at the top end. Being a street car, I have more use for the mid-range. What do you guys think of this turbo for my application? Will it meet my goals?

This is a standard journal bearing turbo. It appears from reading the Garrett site that running pressures over 40 PSI, that a restrictor may be required to reduce flow in the turbo. Have you guys run restrictors in your setups? Do you guys recommend a -3 line for this feed? I also noticed that most of you ran -10 lines from the turbo to the oil drain plug on the case. Is -10 necessary over a -8? It’s tight in there and a -8 would be easier to make work.

I will either buy a muffler from Ben or Brian or fabricate something with a Dynomax Ultraflow. The consensus seems that Ben and Brian’s sound great. I am assuming that I want 3” after the turbo, with the Wide band 02 at this point as well. Any opinions here?

I have read that the Tial 44 W/G flows as well as the 46 and costs less. Does anyone think I’ll have problems with the 44? Given that I am fabricating my options are open.

It seems the BOV’s have springs as well. Do I match the BOV spring to the one on the Wastegate?

Can someone tell me the recommended pipe size for the charge pipe? Is this 3” or something less? I will either buy an aluminum kit or fabricate it from 18 GA aluminized steel. Unfortunately, I am not set up to weld aluminum, only steel.

I will be using the BEGI FPR. Do I need to use the check valve in this application? I also saw a post where someone recommended a check valve on the wastegate. Is this required or typical?

Last, my cylinders are Alusil (10 fins). It seems from my research that several folks have done this without problems. I plan to keep the boost moderate and hope to avoid problems with the cast pistons. My research on the Chevy side taught me that cast or Hyper pistons do fine under relatively high pressure. However, the forged can handle a fair amount of detonation without destruction that that cast cannot. I hope that a mild boost will keep me away from detonation and avoid this problem. Any thoughts here?

Thanks in advance for any help and support you can provide. Once I collect all of the parts and begin the installation, I will start another thread to document the process.