Vetal

iTrader: (3)

OK I've asked about Garrett, BW, PT, seems that since I don't have much space (or at least I think so), I will have to pay $$$$ for compact PT (or wait for a good deal for a used 7675 or PT88)

DrTurbo

iTrader: (3)

Go PT8847. Don't waste time with 7675

Vetal

iTrader: (3)

It's 4X more $$ than I can sel my TC78 now...
In other words, didn't want to spend that much. Will PT88 be much worse? if I find used one till next season

DrTurbo

iTrader: (3)

I would avoid the PT88. The 8847 is a much newer unit and better bearing package.

Vetal

iTrader: (3)

All right, everything is clear, thanks!
THE way to go is PT8847. Then there is PT7675. It all just depends on $$$$ now

DrTurbo

iTrader: (3)

Save a little extra

Shownomercy

iTrader: (1)

If my hotside and surround stuff fits in a 7675 well, would an 8847 drop right in without issue? (other than downpipe redo)

Vetal

iTrader: (3)

Almost overlooked this...
Is this the one you're talking about?
http://store.forcedperformance.net/m...tegory_Code=SP
Do you know dimensions of this thing? Judging by the weight (40#), must be quite big

Vetal

iTrader: (3)

I've studied logs from my GTech and realized that power starts to lower after 5500rpm on medium boost and after 5100rpm on higher boost. Torque peaks at 3800rpm in all cases. I have manual boost controller and cam is Thunder racing 214/220 .600/.523 115 LSA.
Does this sound like turbo is choked? Can that explain my low trap speed, converter keeping the engine at 6200 rpms where power has dropped considerably?

smokeshow

iTrader: (17)

Not necessarily a choked compressor, but definitely reaching the flow cap of that exhaust housing. Peak power at lower RPM with an increase in boost is characteristic of too much back pressure. It most certainly explains the lower trap speed.

big reg

iTrader: (28)

Yes it is but your space constraints probably won't allow it. I was looking at it on a 5.3 as well so only 325ci.

DrTurbo

iTrader: (3)

Same size as a GT42, or S400 T4.

stock48

iTrader: (17)

Yes. You are loosing a lot with the converter slipping like that, and 214/.600" is too agressive of an intake lobe IMO. Like I told you before you need a good turbo converter. No reason why car shouldn't be trapping mid 140's+ with current turbo, and should go mid 150's with a 76/75.

Vetal

iTrader: (3)

So you think my converter is slipping too much? I thought it was designed to stay around 6200+ and my problem is small turbo, no? Converter was custom built by very reputable company for my specific setup, so it was kinda out of suspect IMO...

stock48

iTrader: (17)

If you add more power the problem is just going to get worse. That's way too high unless trans is slipping or something. You want to shift a combo like that at 5800-6k max and converter should drop to 5-5200 rpm if it's right.

Vetal

iTrader: (3)

Why should I limit myself to only 6000 rpm?
Don't know if tranny is slipping (I hope not at such low power), but at 6200 input, TC output is some 800-900 rpms behind

Johnv

That turbo is done on a 383.

I had one on a 383, made just under 700 rwhp turbo was maxed and that was with a 1.32 ar exhaust housing.

I have since replaced the 383 with a forged 347, same turbo, same evrything else and made 770 rwhp, and the turbo still has a bit left in it..
works much better with the smaller cubes.

stock48

iTrader: (17)

The TC78/68 can make 700 hp on 6.0L at 4800-5200 rpm after that it's down hill. If you keep the combo in it's power range it can do work but if it's running 1000 rpm past pk the ET and mph won't reflect the power. I have ran 129.xx with both a Tc76/68, and T78/68 on 6.0L @ 4850 lbs. There is anothe guy on here rhat ran low 9's at 150+ with a 370 ci mustang with a tc78/68. There is more in your combo and the converter is the first place I would look if it does not pull down below 6200 rpm under wot. If you want more rpm than you need more turbine but still you will likely pk at or below 6K even with a 76/75, or 88/94. As you add power the converter is just going to go higher. You can try some John Deere Hygurd in the trans it might tighten you up 2-400 rpm.

Vetal

iTrader: (3)

OK, with current small turbo converter is very unmatched for the setup. But if I put normal-sized turbo that won't run out of steam, wouldn't I be perfectly fine with TC keeping my engine at let's say 6400rpm (a bit higher than current 6200 due to added high-rpm power) ?
Or do you still think it is slipping too much on its own and will do that even with PT 8847?

Vetal

iTrader: (3)

Here's log from one of the runs in case anyone wants to advise