JZ 97 SS 1500

iTrader: (2)

Yes, it did spike up to 987, but it could not sustain it. The boost was dropping back down.

Bens3rdgen

Quote:
Backpressure would be stratoshpheric though[B]

Anyway you could explain what stratoshpheric means. Thx.

JZ 97 SS 1500

iTrader: (2)

Getting close to 3:1 and some setups 4:1. Bascially 20psi inlet pressure would yield 60psi (using only 3:1) in the exhaust. That is not good and will create high EGT's, reversion, and will cause heads to start lifting off the block. The target is 1:1, but with T4 turbos and smaller T6's you shoot for 2:1.

BLk01SS

iTrader: (7)

Ok, I have a question for ya. They tell ya that there good for say 1200hp. What's the probability that it will actually make 1200hp? I mean, are turbos kinda like new cars, in that they tell ya it comes with 400hp when it only dyno's 350? Would you have to have a near perfect setup to get the stated number, or in some cases can you exceed there rating? If someone wants to make 1200hp, should he go with the next size up to achieve that number?

My CAS uses two custom To4e's with 76mm comp. and 56mm turbines, how much do you think there good for, and would running a log manifold keep those numbers down?

smokinHawk

iTrader: (48)

are you talking flywheel HP or RWHP, turbos are reated at fwhp, so you have to figure in drivetrain loss

BLk01SS

iTrader: (7)

ok, I didn't know that. but it still brings up a question as to if you can reallly achieve a number close to the one rated by the manufacture with the drivetrain loss?

Bens3rdgen

Quote:
Bascially 20psi inlet pressure would yield 60psi (using only 3:1) in the exhaust.

So your saying, in order to create 20psi of boost in the intake you going to have 60psi on the inlet of the hot side of the turbo.

Ryan K

iTrader: (11)

Yes, but 60psi is not only on the inlet of the turbo, its the entire hot side exhaust sytem before the turbo. Headers are cool and all, but with any turbo system you are not going to get any Scavenging effect of a "header".

JZ 97 SS 1500

iTrader: (2)

That is correct

NA$TY-TA

iTrader: (21)

Jose where would you draw the line for cubic inches with the GT42 76??
I know as cubic Inches rise so does the back presure...... would you say 364 (stock 6.0L Cubes) 370ci, 380ci?? Im saying that from what you stated with the 383ci and stratoshpheric... post
How high of EGT's are we talking and what would you not want to be over??
Some good to know info for everyone...

Kyle

JZ 97 SS 1500

iTrader: (2)

In the LS1 world I would draw it on a 346, but preferably a 5.3 . Just some quick calculations for you (this will leave alot of details out since it can take forever to explain all of it)...., this one will leave you scratching your head

346 @16 psi = 86 lbs/min consumption

383 @ 16 psi = 95 lbs/min consumption

Using a map that is available, lets look at the GT42-74.

At those levels

346 = 63% compression effic.
383 = 49% compression effic.

Using those #'s, a 346 will lose ~95-99hp to drive the turbo at that level (ala efficiency, which will net us ~885 hp

Using the same calcs above, the 383 would require ~160hp to drive the compressor at that level, which would in turn net us only ~873hp

So now you see why small cubes and efficient boost is so important.

RealQuick

iTrader: (14)

Jose, according to your site:

http://www.forcedinductions.com/consumption383.htm

383 @ 19psi @ 6700rpm = 95lbs/min. I dont think too many street car 383's will see those boost numbers or rpms.

My plan is 6000rpm @ 15psi which is alot more reasonable requiring 75lbs/min. That pushes the turbo back into a good eficiency range (not as good as an 88m though ).

Is your link wrong as far as lbs/min? Just wondering because I have been using those numbers fo awhile when calculating.

JZ 97 SS 1500

iTrader: (2)

The #s in the site are based on stock components, just bigger cubes. I based these #'s off a well ported set of LS1 heads and LS1 intake. VE will rise with a good flowing engine. Most of these turbo build on this site use those parts.

NA$TY-TA

iTrader: (21)

There are no compressor maps for the GT42-76 correct??

I am just wanting to see were my 370 and the 76 would be for lbs/min consumption for 20-22 psi and how much HP its eating and a realistic goal with it.

If its limiting me that much i can forsee the swap to the S88 even sooner.
Thanks JZ
Kyle

Bens3rdgen

Great info, thx.