Alright thanks.. I'll be waiting for results

I understand why yall are saying get a smaller turbo since this is a DD truck(for now). I checked out the compressor map of a PT88 and compared to a 364 ci motor it looks to be a good match staying in the 85% efficiency range while not having any turbo surge. Then to double check that, I called Precision Turbos and told them what my goals were to see which turbo they would recommend. Of course if was the brand new $3390 ball bearing unit out.. but it was an 89mm exh/88mm comp. However, they did say a PT88-47 would be sufficient for my future goals(single digits).

Also, I know that the T4 flange will be hurting performance on larger cubed motors but I'm most likely going to stay with a 370 ci. But doesn't flaco have a PT88-47 on a 427 cubed motor?? Or is he running the T6 version?? I saw him run a 9.1x @ 15x before.

 

Where did you find a compressor map for the PT88? I never could find one.

 

I can't remember off hand, but I'll see if I can dig it up by going through my history.

 

thats kinda funny because 2 years about i had a pt88 on a 365cu ls1 and i kept breaking the journal bearing and precision said that the turbo was seeing excessive backpressure and that i needed a larger hot side for the cube motor. it was nothing crazy either, stock 317 heads and 20psi of boost reving to 6500rpm of so.

precision said the pt88 was built for the grand national guys for a particular class. it likes less cubes and the hot side a/r is limited to .96 i believe.

 

Not trying to argue with what you're saying.. but I'm getting a little confused.
In your first post you're saying that the PT88 will be too big and have too much lag for a Lq4.

In your second post you're saying the PT88 likes less cubes than 36x ci.

If the Pt88 in fact likes less cubes would it spool fine on a Lq4?? If it makes a difference I'm looking into the PT8847H which has a GT4788 CHRA bearing and is rated to 1400HP. It's supposed to spool faster than the standard PT88.

 

My old set up was a TC-78 .96 a/r .. Built 6.0 9.5 comp and WCCH heads...
It spooled to quick and choked up top... Boost was instant , but to violent in my opinion.
I now run a GT91 T-6 set up on the same engine, alot more control and pulls like no other!
Night and day difference.
I would say the PT-88 over the TC-78, but would go T-6 if possible... I wish I would of done that from the start..

 

Precision also said that one day if the T4 was holding me back I could upgrade the exhaust housing to a T6 style flange but they wouldn't recomment anything bigger than a 370 cu in.

 

yea the pt88 would be laggy. here is why, its going on a truck. the turbo was intended for grandnation v6s(according to precision), leaving on a transbreak and 2 step. much different than a street truck.

when you see a dyno pull with the torque higher than the horsepower...you know the turbo was choking. an example was with my pt88, i make 800rwhp and 820rwtq. thats a T4 flange on 22psi. on a t6 S91, 988rwhp, 850rwtq on 17psi.

if turbos have low backpressure they will really start to shine uptop. a choked turbo will go flat. my setup went flat and the new setup pulls an extra 200hp. thats a lot more power for only 3mm more tubine and less boost.

additionaly, the physical size of the pt88 is little compared to a t6 S series turbo. personally i went through 3 pt88s and wouldnt put another on my lawnmower. there are much better turbos to chose from, a T6 S76 will blow a t4 pt88 out of the water, but some people just want to say "its an 88mm"

 

We've had our arguments, but I definitely agree with all of that...

 

arguments? i call them constructive conversation