88 turbo???

[qwknuf6]

Any downsides going from a LT76 3 bolt turbo ,Q trim turbin wheel PTE .85 exh hsg to a

LT 88 turbo ,is it just a comp wheel upgrade , the 76 turbo I have now is very steetable

[John Wilde]

You may want to ask around.
The people I have spoken to did not like anything
bigger in the small housing than a 76. It slowed them
down. I don't think the turbine housing can flow enough
to keep the back pressure low. Ask around!!!

[JoyOf6]

I don't know if this helps, but I ran an LT-88 3-bolt 0.85/Q for 2.5 years, and could easily run 30 psi. Street behavior is too subjective for me to comment on.

Art

[John Wilde]

Art,

This was not a slam on Limit, I was just stating what I had been told by 2 seperate people regarding 80 or 88mm smaller housing turbos. One Person had a stage 2 headed 272 and his small 88 would have a so much back pressure that the car would not run faster than low 10s. With a Precison 88m "big housing" it has gone 8.6s. The other car has a TT SBC. When going from twin 76s to twin 80mm small housing turbos it lost almost 150hp.
This is not a theory, it is dyno tested by a leader in the turbo charging community.

[lazaris]

Recently I asked John about this as well and he did state that and 80mm wheel on up in the T frame compressor housings begin to see too much BP on the compressor side as the housing does not flow enough air. Now will an 80-88 wheel make more HP over a 76 wheel in that same housing, I dont know. But BP does beome a problem, according to John.C.

[JoyOf6]

I just posted my recent experience with a specific turbo since it appeared pertinent to the original post. I did not move from a 76 to an 88 in this configuration so it's just an unpaired data point, perhaps of no value.

Art

[qwknuf6]

Art

Thanks for the input ,I was thinking about cars with 88 turbos and yours came to mind , I have run 24 lbs of boost so far on My 76 and will try to get to 30 psi and see how it runs ,just thinking of the future .

I called a spoke to Limit Eng today,it is a doable deal to go from 76 to 88

Thanks to all for the inputs

[Mac in SD]

Originally posted by JoyOf6
I just posted my recent experience with a specific turbo since it appeared pertinent to the original post. I did not move from a 76 to an 88 in this configuration so it's just an unpaired data point, perhaps of no value.

Art

Art, you been watchin' a lot of old Star Trek episodes? I'd swear Spock said that to Dr. McCoy.

"DAMMIT, Spock! I'm a DOCTOR! Not a turbine engineer!!"

[John Wilde]

qwknuf6 ,

Please tell us what Limit said !!!! =)

[qwknuf6]

Originally posted by John Wilde
qwknuf6 ,

Please tell us what Limit said !!!! =)

I talked to Bill ,went something like this

Me : Can I get my 76 changed to 88 turbo ?

Bill: What size inj do you have ?

Me : 83lb inj

Bill: those are to small for a 88 turbo ,it flows 111 cu ft air per min and the 76 flows 91cu ft per min , you have to add the psi of boost to come up with inj size ,no wait subtract boost ,I cant rememer how to do that now

Me : Ok ,besides cost are there any downsides?

Bill : There will some Backpresure issues ,Terry Houstons car had high backpresure with his setup (8.6 car)

Me : so what will it cost to upgrade ?

Bill: bout 600.00

[Reggie West]

My Dad did that same upgrade like you are thinking Qwknuf.

We used a 4 bolt turbine Q trim housing and we could not get that thing to spool it was just too big. We had tried a 8 inch 4500 stall converter, a 9 inch 4000 stall and to no avail. Now mind you this is with a Stage 2 motor and M&A heads.

I do think that turbo will work but you must have a cam that wants to wind the motor to 8000 rpms. No joke. This was with a 4 bolt turbo. Now I know that Cal Hartline is using a 3 bolt 88 and it is working for him so I am not saying it cant be done.

John Craig told me the same thing when I talked to him about the spooling issues with the 88. Big compressor ( read massive by any terms) needs more exhaust gas to get it spinning. He was not surprised.

This was our solution. A ball bearing 80 from Cotton. Spools quickly, right at the stall speed of the converter ( 3800 ) which I still think we could lower and create less slippage in the converter.

Backpressure is a problem with this monster 80 or 88 it does not matter. We had to use a 3.5 inch ID downpipe and that problem went away. By the way, if you dont have a racegate or similar wastegate on the car, you will need it. Once that 80 was slapped on the boost started to surge halfway down the track.

Something to think about....hope it helps