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#16
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Hmmm only a 18hp difference between 9lbs with daul exhaust and 12lbs with single. Ya Tom, you defenitly need to look into the exhaust.
Paticularly in the area between the manifolds and the Y-Cat. That is were the largest amount of restriction is. Those pipes are only like 1.5 inch in diameter. Lose the Y-cat and run 2 hi-flow Cats that are larger diameter. If you dont want duals, I'd recommend at least 2.25in off the manifolds, through 2 high flows Y into a 2.5 to 3inch out to the rear. Just beware of resination. I'd definitly put in some kind of resinator no matter what kind of exhaust you run. |
#17
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I haven't gotten a chance to download the dynojet software and see if I can figure out how to put the plots x axis on rpms and overlay Mike's and Tom's plots but yes even just looking at them as is it's easy to see that Tom's exhaust is restricted.
Mike's peak power is out at 90mph. Tom's is at 75. It looks like back around 60mph he starts having problems clearing the exhaust from the cyllinders. He should see big power gains with a big exhaust upgrade. I would not be suprised if Tom is having belt slip issues because of the compressor having to pump against the exhaust. Both of them can see big power gains (after TOM upgrades his exhaust) from new cams. With the cam I just spec'd in the cam thread I think they can both get their torque plots into pretty flat lines and their power plots into flat lines following the slope from 60mph and lower. |
#18
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Torque drop off.
If it is the exhaust that is restricting the engine, you should see a rise in manifold pressure, at the same time. I wonder if he noticed the boost gauge at that time.
Harvey.
__________________
One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#19
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Quote:
Harvey.
__________________
One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#20
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possibly but not necessarily. All kinds of weird things can happen, all bad. The blower can win out and still clear the cyllinder during overlap at the cost of more power to drive it. The blower could loose the battle without the belt slipping. The blower could loose the battle with belt slip. The blower could win the battle with belt slip. There could be a tie with belt slip. There could be a tie without belt slip. And favorite of all, things can bounce back and forth between any number of those conditions. Manifold pressure can end up higher, lower, unchanged, or all over the place.
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#21
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Quote:
The boost gauge is a sure way to see what the flow is doing. Need all the feedback you can get, to work out what is happening. Harvey.
__________________
One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#22
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Dyno plots.
If somebody can translate the MPH figures to RPM, off what ever the gearing was, it would help to see what is happening where. Guessing is not close enought.
Harvey.
__________________
One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#23
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Your plots
Great job guys. Great to see your projects working out well. I had a question regarding some of the plots. Is there any reason why Mike's seems to be running higher A/Fs? Is it due to the lower boost level? It was my understanding that this 12 psi kit was to run AFs as low as 10.5:1. I'm not sure about the 9 psi kit.
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
#24
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Great results guys, cant wait to see what Toms car puts out when he gets it sorted.
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Harvey. There in lies your error. You can have the same pressure ratio at the cost of a lower density ratio, and therefore not just look at the boost pressure but we must also look at temp to come to the conclusion you are trying to reach
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
#25
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exhaust is comming... I am thinking dumps but I may do a total revamp. Intake is comming too. I am busy getting the garage ready... plus I have all winter to het this figured out
Tom |
#26
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Mike,
Nice videos! It does look like Tom's belt is slipping in the one video, but then again, it could just be the lighting (watch where the the belt goes around the a/c compressor) Interesting to note that even with the Gruppe N motor mounts that the engine is visibly torquing around...hate to think what would be happening if the stock mounts were in there -Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#27
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they would rip in half and hit the keepers?
GroupN trans mount too Tom |
#28
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Quote:
That's what I was thinking....might be time for a torque strap -Bill
__________________
Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#29
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Quote:
A sudden rise is usually exhaust gas pressure build up. Intake restriction, builds up more gradually, to a higher bressure. This is a bit harder to do with a turbo, due to the fast rise in boost. Turbos have there own set of problems. Harvey.
__________________
One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#30
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Are you two working your own grumpy old men sequel?
It didn't really seam confusing to me. Let me put it in simpler terms. Because we only have a 6 rib belt and a tiny supercharger pulley instead of boost spikes we can get belt slip. Depending on the degree of slip boost can stay stable, have dips, or have spikes. Quote:
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