Header leak causing HIGH egt's???
- Thread starter Spooled
- Start date
Well potentially, but 500 hp worth of exh is still basically 500 hp worth of exh as far as the turbine is concerned. An easier time of it on the big inch mill though, compared to us 2xx guys 
Less pressure involved, less heat, etc. There are plenty on here who have made 700, 800, more flywheel hp with the basic T4 exh setup and an .81 range hsg. That hsg is not the holdup here.
A loose rocker?? That might be a big issue by itself
TurboTR
Less pressure involved, less heat, etc. There are plenty on here who have made 700, 800, more flywheel hp with the basic T4 exh setup and an .81 range hsg. That hsg is not the holdup here. A loose rocker?? That might be a big issue by itself
TurboTR
What kind of intercooler do you have? Ever checked how much pressure drop you see across it? 13 psi intercooled gives you about the same charge density as 19 psi nonintercooled, so I'm not surprised that your times are close between 13 psi with the intercooler on and 19 with it off. 19 psi with it installed should be a big improvement though! Unless it is choking things off for some reason... A boost gauge installed between the turbo and IC would show a problem if there is one there, just make sure it is good up to the pressure that your blowoff valve is set for so you don't spring the gauge when you let off the throttle.
If you really think that excessive exhaust backpressure could be the problem (due to a retrictive turbine wheel or housing, or downpipe, muffler, etc...) a pressure gauge at the turbine inlet would be instructive as well. If you see 100 psi there, you've found your problem
As for where you are on the compressor map, it looks to me like that T-72 is about perfect for you, assuming you're not revving it up to 7k+.
John Estill
If you really think that excessive exhaust backpressure could be the problem (due to a retrictive turbine wheel or housing, or downpipe, muffler, etc...) a pressure gauge at the turbine inlet would be instructive as well. If you see 100 psi there, you've found your problem
As for where you are on the compressor map, it looks to me like that T-72 is about perfect for you, assuming you're not revving it up to 7k+.
John Estill
nightdiver
New Member
- Joined
- Feb 25, 2002
I bet you run a distributor
Ive seen like 10-15* minus above 2500 rpm from a worn shaft
Ive seen like 10-15* minus above 2500 rpm from a worn shaft
I do run a distributor. Couldn't I check that just by free revving it and checkign with a timing light? I'll have to try that. i've had it up to around 3000 and it was still right on. I'm installing a pressure guage in the exhaust this weekend. I'll see what i come up with. I'll also put a pressure guage right on the compressor hosuing and see what kinda pressure i'm loosing in the I-cooler. I'll report in
UPDATE
I hooked up a pressure guage in the exhaust today. I put it in the crossover pipe after one of my deltagates. It read about 55 lbs of pressure at about 18 lbs boost. And about 32 lbs pressure at about 13 lbs boost. I think that sounds a little high. Anyone know for sure? Any thoughts on my readings?
I hooked up a pressure guage in the exhaust today. I put it in the crossover pipe after one of my deltagates. It read about 55 lbs of pressure at about 18 lbs boost. And about 32 lbs pressure at about 13 lbs boost. I think that sounds a little high. Anyone know for sure? Any thoughts on my readings?
nightdiver
New Member
- Joined
- Feb 25, 2002
Anything more than double is high and this is
Hows that ?Why dont you check your muffler, you never know
Hows that ?Why dont you check your muffler, you never know
Well for ref I saw about 45 psi with 25 psi boost. Something strange there with yours. If not the muffler or exh system, then ?? Maybe the intake has a big restriction somewhere (?) Might be time to measure that pressure drop too.
One time I left a shop rag inside an intercooler pipe...
TurboTR
One time I left a shop rag inside an intercooler pipe...
TurboTR
I'd think you'd expect lower exhaust pressure differences with an intake restriction.
From how you've described your exhaust, as long as there aren't 4, 180 degree bends in it I don't think it's your problem. To rule it out, put a pressure guage after the exhaust housing also, and look at the differences.
From how you've described your exhaust, as long as there aren't 4, 180 degree bends in it I don't think it's your problem. To rule it out, put a pressure guage after the exhaust housing also, and look at the differences.
I don't think it is the exhaust after the turbo either. There's two 90 degree bends and that's it. I'm THINKING about getting a precision .96 tangential housing to replace my .81 tangential. I dont' want to waste my money though. Think I would be? I dont' think there's a restricion in teh intake. It's just a 75mm TB, a short piece of 3" pipe goin into an accel carb/efi intake. I dont' even know where else to look now...or what to even test.
ChrisCairns
Senior Member
- Joined
- May 24, 2001
Stick your finger into either side of the turbo .... see if it turns freely.
(Don't use the "important" finger...you may need that when someone cuts you off in traffic.
)Chris
TwinTurboIroc
New Member
- Joined
- Mar 5, 2002
Still running that Diesal intercooler?
Yes I am, today or tomorrow i'm going to put a boost guage on teh comrpessor hosuing to see exactly how much pressure drop i'm seeing. I just got an email from PTE. Here's what they said:
The real problem, is with the sizing of the turbo.
That turbo was spec'd for a V6 application, not a V8. If we were to spec a turbo for your application today, it would be a PT74 Q-trim turbo. Another thing, we no longer make the PT72 in a P trim, it's only sold as a Q trim today. Also, changing the housing would not see a significant increase in power, only by going with the larger PT74 Q-trim would you really see a significant change. I know this is probably not what you wanted to hear, but
just wanting to let you know.
So they say the turbo isn't big enough. Im finding this hard to believe. A T-72 P trim can't push my car any faster than high 10s? That's about 525 RW HP.
The real problem, is with the sizing of the turbo.
That turbo was spec'd for a V6 application, not a V8. If we were to spec a turbo for your application today, it would be a PT74 Q-trim turbo. Another thing, we no longer make the PT72 in a P trim, it's only sold as a Q trim today. Also, changing the housing would not see a significant increase in power, only by going with the larger PT74 Q-trim would you really see a significant change. I know this is probably not what you wanted to hear, but
just wanting to let you know.
So they say the turbo isn't big enough. Im finding this hard to believe. A T-72 P trim can't push my car any faster than high 10s? That's about 525 RW HP.
TwinTurboIroc
New Member
- Joined
- Mar 5, 2002
get a few more opinions.....call
john craig @ limit engineering
rick head @ innovative turbo
john craig @ limit engineering
rick head @ innovative turbo
Originally posted by TurboTR
Back in the mid 90's I got to watch a T-72 p-trim GN run low 10's at over 130 mph up in the NW area
TurboTR
With the tune set on kill I expect.
Spooled sounds like he's set on warm right now.
In the long run I'd say he's going to need to step up the turbo size to be happy. Is there more left in the tune, yes. Is everything he's looking for there, I don't think so.
I think what PT&E was trying to tell you is that the turbine side is a bit small rather than the compressor side. The T-72 map I looked at seemed to be a pretty good size for the boost levels you're running, presuming you aren't revving it up over 6k or so. Once you get this thing all lined out and start pushing it I can see the need for more, but not right now.
I wish there was more information available about the turbine wheels and housings, I have no idea if a P trim or a Q trim is adequate, borderline, oversized, or anything. Just have to trust them on this one I guess. The fact that they only hook a Q trim up to a 72 is an indication that it is a better match to that compressor than the P trim though.
It does sound like your backpressure is a bit high for some reason or another. If it is due to the turbine wheel size and turbine housing, then upgrading will be your answer. Maybe they can upgrade your turbine wheel and housing and keep your existing compressor wheel and housing? Might save you a few $$$ if they can.
A restriction in the intake could cause this to happen. Suppose your intercooler had a 10 psi drop. Then to make 19 psi at the intake (which is what your boost gauge and MAP sensor would be seeing) you would have to have 29 psi at the compressor outlet. It requires a lot of hp to make that much boost, and the more hp the turbine has to supply to the compressor the higher the exhaust backpressure has to be. That would lead to the big imbalance between the MAP and the exhaust backpressure that you are seeing.
When you checked your backpressure at 19 psi, was this with or without the IC in place? I remember you made some runs previously without the IC in place.
John
I wish there was more information available about the turbine wheels and housings, I have no idea if a P trim or a Q trim is adequate, borderline, oversized, or anything.
Just have to trust them on this one I guess. The fact that they only hook a Q trim up to a 72 is an indication that it is a better match to that compressor than the P trim though.It does sound like your backpressure is a bit high for some reason or another. If it is due to the turbine wheel size and turbine housing, then upgrading will be your answer. Maybe they can upgrade your turbine wheel and housing and keep your existing compressor wheel and housing? Might save you a few $$$ if they can.
A restriction in the intake could cause this to happen. Suppose your intercooler had a 10 psi drop. Then to make 19 psi at the intake (which is what your boost gauge and MAP sensor would be seeing) you would have to have 29 psi at the compressor outlet. It requires a lot of hp to make that much boost, and the more hp the turbine has to supply to the compressor the higher the exhaust backpressure has to be. That would lead to the big imbalance between the MAP and the exhaust backpressure that you are seeing.
When you checked your backpressure at 19 psi, was this with or without the IC in place? I remember you made some runs previously without the IC in place.
John
i would say it is time for a turbine wheel upgrade
u like in a perfect would be see the ratio 1:1 compressor psi to turbine psi but we except 1:2 anything more then that and it is time for an upgrade
our mustang we run is a street car with of stock block 302 alum stage II heads box intake w/automatic aode 3000 stall with a t-76 q trim 96 housing went a 6.80 @ 109 on drag radials with only 14psi
just my 2 cents
u like in a perfect would be see the ratio 1:1 compressor psi to turbine psi but we except 1:2 anything more then that and it is time for an upgrade
our mustang we run is a street car with of stock block 302 alum stage II heads box intake w/automatic aode 3000 stall with a t-76 q trim 96 housing went a 6.80 @ 109 on drag radials with only 14psi
just my 2 cents
