stevewix

Hey guys, about a month ago I dyno'd my car on a mustang MD1750, made it to 710 rwhp @6000 rpm through an unlocked turbo 400 @ 21psi. going to 22psi made the exact same power, and literally grenaded one of the exhaust manifold gaskets (multi-layered aluminum made by percys). Maybe i'm the dumbass for running aluminum manifold gaskets, but the old gasket has a gap somewhere around .25" wide. It isn't BURNED, it's ragged and looks like it simply exploded.

Getting to the point of my post, I've never checked exh. backpressure, I'm running a gt47-88 with .96 a/r housing on a 370. Is it possible i was out of power on the dyno after 21psi because the exhaust housing is too small? I've never hooked up a pressure gauge to the exhaust side, is there a certain gauge or sensor that will take the heat?

I would be interested to know what a/r some of you out there are running on similarly sized turbochargers.

Fireball

iTrader: (21)

Mine is a 1.08 and so is PSJs

DrTurbo

iTrader: (3)

GT47-88 turbine wheel is not the best flowing wheel. When it came out it was a great piece over the older TV series stuff. You need to hook up an exhaust pressure gauge to that. I would bet, that your BP was probably around 45-55psi which is to excessive for a setup like that. We keep seeing alot of customer that run smaller units on these big, high flowing LSX series engines continue to have head gasket and high EGT problems with even mild tunes. Also as for power, that # on a dynojet is probably close to 800-830rwhp through an auto. Its getting close to stalling, but the compressor will push past the 900rwhp range even though backpressure will be VERY high. You may have problems with reversion if you continue to go any further.

Pro Stock John

iTrader: (34)

When I bought my turbo from Kurt @ W2W, he and the guys at PTE were saying that the 1.08 would make a bit more power, so I went for it. Jim @ Speed Inc. said my car did 867rwhp @ 26 psi @ 20 degrees of timing on C16 with an a/a intercooler, and an 7.9:1 348ci engine. Brian M. at PTE has indicated on several occasions that this turbo can make 1400hp, and has powered some guys into the high 7's though the low 8's are more common.

You might have just found the limit of that gasket too.

I made 680rwhp and went 144 with my old blower setup. So I guess I should hope to run 160mph.

Fireball

iTrader: (21)

adding the .96 housing to the marginal wheel surely isn't helping

smokinHawk

iTrader: (48)

there fixed it for you

y2khawk

iTrader: (5)

Pro Stock John

iTrader: (34)

Hey smokincrack, have you made a pass in 2-3 years? Thank you.

Intercooler Steve??? Jim (Intmd8) thinks I should eventually look at my intercooler and see if adequate for my power level, though I think he thinks it's a restriction and I could do better.

smokinHawk

iTrader: (48)

why yes, yes i have, made allot of passes last year (*awaits his when you run a blah@blahmph pass come talk to me line)

DrTurbo

iTrader: (3)

John 1400 hp with a small displacement (2.0-3.0L) could be made, but the big CI LSX engines it will not. Just talk with some of the NMRA DR guys in that class. Ask them why they don't run the GT47-88, when their is a 88mm limit in that class. I know we have some data here from some of the runs made with those turbos in that class when the 88 ruled was implemented. The backpressure #'s were very high and with only 360ci engine limit. They now are going straight to a 98mm thumper trimmed to 88mm and still are only running consistent low 8's@170-175.

DrTurbo

iTrader: (3)

Nope its not.....

$ho_tyme

iTrader: (3)

So is my gt4202R with a 1.01 and has a t4 foot going to suck on my car?

Only plan run @10psi with a 60mm wg. Sorry not trying to hy-jack just kinda close to same prob. btw its on a 6L

y2khawk

iTrader: (5)

with only one, yes

$ho_tyme

iTrader: (3)

OK I will proceed to go cry now maybe I will sell it and go buy 2 gt40s then.

DrTurbo

iTrader: (3)

I think people forget about Kyle's (NA$TY-TA's) car having a GT42-76 on it and then swapping to an S88 and picking up huge mph. The 42-76 is good for smaller engines.

y2khawk

iTrader: (5)

Thus my response. Drove it both ways, the 42 was a pooch

NA$TY-TA

iTrader: (21)

Got to listen to the man.. he drove my car both ways.... at the track.. .
Thats with 370 cubes also...
My A/R on my S88 is a 1.32.......BTW...

DrTurbo

iTrader: (3)

Yup the S88 made the GT42-76 looks like a T25.

stevewix

the intercooler is an A/W PTE unit rated for 1500hp.

Can someone suggest a good starting point that won't kill my spool time? I appreciate all of your help.

Fireball

iTrader: (21)

Here are the turbine flow maps for the GT47



As you can see, the turbine flow stalls at ~43 lb/min for the .96 A/R, ~46 lb/min for the 1.08, 50 lb/min for the 1.23 and 56lb/min for the 1.39.