Back pressure test results, when is it too much?
04-18-2012, 08:33 PM
#23
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Im so limited with space, that thing is probably alot bigger than my compact comp turbo. Comp said they have a 1.52 ar housing I could try. I wish they could fit a larger turbine wheel I there.
04-19-2012, 02:09 AM
#25
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Precision have a range of cea turbines that Flow better for any given size, or you could maybe have the turbine wheel clipped. Larger housings aren't the only option.
I think the turbine wheels used in Garretts billets also flow better than old wheels.
I think the turbine wheels used in Garretts billets also flow better than old wheels.
Last edited by stevieturbo; 04-22-2012 at 03:36 AM.
04-22-2012, 05:46 AM
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The OP already proved the 79mm turbine billet compressor combo won't work on a 370. Comp exchanged it for this one.
Comp spec'd a 1.15 on an 8079 would work for me on a 347 for 1khp.
I ended up finding a 6.0 30 miles from me so I couldn't pass it up.
Based on the OP's numbers, I'm going to sell my 8079 due to BPR.
Based on the BP number the OP has seen, it looks like about how a 76HPSH would run on a 355. Just a little more power.
04-22-2012, 10:29 AM
#28
In my opinion you should've measured back pressure downstream (at the downpipe), to get a better overall view of how effecient the turbo/exhaust system is as a whole. High pressures upstream is not as detrimental to performance as it is downstream. In fact higher pressures in the header helps turbo performance more than it hurts. Look at what a quick spool valve does and how much higher it raises perssure, yet improves spool-up.
04-22-2012, 11:45 AM
#29
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Turbo s10, so what turbo are you going to with? Also keep in mind before you sell it. Not many test bpr and post results. If your in need of a small frame turbo due to space limits you don't have many options that are going to have less bpr.
04-22-2012, 07:15 PM
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I bought a GT4788r -
71 Nova- not worried about cutting anything, I'll make it fit.
I could have went and got a 5.3 and made it a 5.7. Probably should have....
But money wise it will be a wash since the GT after selling the 8079 will end up costing me about what a 5.3 would.
I think the 8079 is perfect for a 5.3 w/ported heads. If my overtime hadn't dried up I would have tested it just to see....I need to sell the 8079 before curiosity gets the better of me and I stick it underneath the jimmy! I already need to cut the exhaust a part and want a different muffler...
jmop- but I like your cam as a 236/232. It's what I plan on running.
LS1Curt has one in his S88 370 build. I'm basically copying 98Z28Cobrakillers' build.
71 Nova- not worried about cutting anything, I'll make it fit.
I could have went and got a 5.3 and made it a 5.7. Probably should have....
But money wise it will be a wash since the GT after selling the 8079 will end up costing me about what a 5.3 would.
I think the 8079 is perfect for a 5.3 w/ported heads. If my overtime hadn't dried up I would have tested it just to see....I need to sell the 8079 before curiosity gets the better of me and I stick it underneath the jimmy! I already need to cut the exhaust a part and want a different muffler...
jmop- but I like your cam as a 236/232. It's what I plan on running.
LS1Curt has one in his S88 370 build. I'm basically copying 98Z28Cobrakillers' build.
Last edited by TurboS10; 04-22-2012 at 07:24 PM.
04-23-2012, 08:01 PM
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Ok got my brand new boost gauge in that goes to 60psi and did some high way testing. Looks like it 2:1 at every boost level. Intake pressure: exhaust
9.5:20
14.6:30
17.6 35
19.3:38
Id say thats pretty normal for a t4 turbo on a 370 with ported heads and a cam.
Any one else have results?
9.5:20
14.6:30
17.6 35
19.3:38
Id say thats pretty normal for a t4 turbo on a 370 with ported heads and a cam.
Any one else have results?
04-23-2012, 11:23 PM
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i have bungs in my headers but not at the turbo merge. if i measure backpressure at the collector at the header will the results be any good? id like to measure, but dont wanna hack into my cross over just to test as it runs good, im just curious. so basically anyone measure at the collector area and compare to right before the turbo?
04-23-2012, 11:47 PM
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It doesn't work like that. Turbine can only flow so much before it breaks 1:1 barrier, after that, the turbine inlet pressure rises faster than your boost level. And why plan for a 1:2 ratio, get the correct turbo.
But Got-A-LS1 it doesn't matter if its before or after waste gate, Exhaust Manifold pressure is measured at the turbine inlet.
This is where they should be ideally. Only using 2 due to divided housing.
Last edited by turbociv910; 04-24-2012 at 12:00 AM.
04-24-2012, 03:45 AM
#39
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Pressure can be monitored anywhere between the turbine and the exhaust valve. Pressure throughout the actual tubes wont vary that much.
2:1 certainly isnt great, but again if it's a fast spooling setup I wouldnt be too concerned. If however it is still quite slow to spool then it's just a bad setup.
2:1 certainly isnt great, but again if it's a fast spooling setup I wouldnt be too concerned. If however it is still quite slow to spool then it's just a bad setup.