Changing hotside from .82 to 1.05
#52
Senior Member
Thread Starter
Howard,
Since this thread I've been thinking about the method of measuring exhaust manifold pressure.
I am having doubts about the effectiveness of measuring via a port in the manifold runner or at the entrance to the turbo.
Bernoulli's principle states that as velocity increases, static pressure drops.
Measuring static pressure anywhere inside the manifold would be totally influenced by the velocity of the exhaust stream.
I'm thinking the best place to measure may be the EGR port.
Since this thread I've been thinking about the method of measuring exhaust manifold pressure.
I am having doubts about the effectiveness of measuring via a port in the manifold runner or at the entrance to the turbo.
Bernoulli's principle states that as velocity increases, static pressure drops.
Measuring static pressure anywhere inside the manifold would be totally influenced by the velocity of the exhaust stream.
I'm thinking the best place to measure may be the EGR port.
#53
Arrogant Wankeler
Howard,
Since this thread I've been thinking about the method of measuring exhaust manifold pressure.
I am having doubts about the effectiveness of measuring via a port in the manifold runner or at the entrance to the turbo.
Bernoulli's principle states that as velocity increases, static pressure drops.
Measuring static pressure anywhere inside the manifold would be totally influenced by the velocity of the exhaust stream.
I'm thinking the best place to measure may be the EGR port.
Since this thread I've been thinking about the method of measuring exhaust manifold pressure.
I am having doubts about the effectiveness of measuring via a port in the manifold runner or at the entrance to the turbo.
Bernoulli's principle states that as velocity increases, static pressure drops.
Measuring static pressure anywhere inside the manifold would be totally influenced by the velocity of the exhaust stream.
I'm thinking the best place to measure may be the EGR port.
I'd agree than any comparison in intake to exhaust manifold pressure above about 2500rpm is meaningless unless you are very near 100% throttle, there could have been a significant pressure drop across the throttle at those revs which requires more turbine energy (and thus pressure to drive). Do you have wastegate position sensors? Would be easy enough to do back to back runs to compare.
Edit: predictive text is a PITA.
Last edited by Slides; 12-31-21 at 07:43 PM.
#54
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#56
10000 RPM Lane
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why would it be any different at all?
it may be static there, but it’s not static at the source opening, which it will only reflect the pressure from that point.
seems to be a hair splitting exercise because the magnitude difference is likely being given more weight than it deserves.
.
it may be static there, but it’s not static at the source opening, which it will only reflect the pressure from that point.
seems to be a hair splitting exercise because the magnitude difference is likely being given more weight than it deserves.
.
#57
Senior Member
Thread Starter
My thought is that when measuring static pressure in a high velocity stream, such as a turbo manifold runner, the data collected may be as heavily influenced by the location of the measurement as the design of the manifold.
By measuring as close to the inside of the rotor housing as possible you may get a much more accurate representation of the "backpressure" the engine sees and therefore a better picture of how a particular turbo system (turbocharger, manifold, wastegate, and exhaust system) performs.
By measuring as close to the inside of the rotor housing as possible you may get a much more accurate representation of the "backpressure" the engine sees and therefore a better picture of how a particular turbo system (turbocharger, manifold, wastegate, and exhaust system) performs.
#58
10000 RPM Lane
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I was referring to the ACV vs EGR port part of the conversation, but I’m still of the opinion it may be given more weight than deserved. It’s not even constant, but cycles when you get down to it.
There’s velocity coming through the throttle body as well and right behind it is considered the optimum measurement point for the MAP sensor. Should there be concern about the accuracy of it too?
There’s velocity coming through the throttle body as well and right behind it is considered the optimum measurement point for the MAP sensor. Should there be concern about the accuracy of it too?
#59
10000 RPM Lane
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A G30-770 from ATP will be arriving here soon. This is a secondary project to my other RX8 and will likely be a bit before results are ready, but we’ll get there eventually.
I’m confident 66 lb/min @ 70% compressor efficiency and 30 lb/min turbine capacity @ 74% eff. is going to show that it's more than “good for 450 whp”. But let’s put aside referencing data/technology from over two decades ago and find out what’s really possible with where we are now instead …
.
Last edited by TeamRX8; 01-05-22 at 05:08 AM.
#60
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I was referring to the ACV vs EGR port part of the conversation, but I’m still of the opinion it may be given more weight than deserved. It’s not even constant, but cycles when you get down to it.
There’s velocity coming through the throttle body as well and right behind it is considered the optimum measurement point for the MAP sensor. Should there be concern about the accuracy of it too?
There’s velocity coming through the throttle body as well and right behind it is considered the optimum measurement point for the MAP sensor. Should there be concern about the accuracy of it too?
not sure what difference that would make if any, i'm sure someone thought of it before, but it didn't really occur to us until about a year ago.
boringly, the US/EU 93-94 intakes are the only ones with EGR, although the engine seems to have that port all the time
JDM intake for comparison
Last edited by j9fd3s; 01-05-22 at 09:42 AM.
#61
10000 RPM Lane
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I can’t say for sure, but am questioning whether it matters wrt being any more accurate for the reason stated. There are other threads on the forum stating at the turbo entrance is more accurate. Pretty much just like anything else, such as using 2” Sch. 10 vs 1.5” Sch. 40 for the turbo piping and hundreds of other things we go on about.
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j9fd3s (01-05-22)
#62
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#63
brap brap brap
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I'm running mine from acv too ffe canister kit. have only take a log or 2 on my setup.
IRP manifold with 8374 IWG
from what I saw so far (albeit brief) emap seemed to be mostly lower then imap. I did notice at one point though at start of boost emap actually showed pressure before for imap for an instance before imap took over
IRP manifold with 8374 IWG
from what I saw so far (albeit brief) emap seemed to be mostly lower then imap. I did notice at one point though at start of boost emap actually showed pressure before for imap for an instance before imap took over
#64
Racing Rotary Since 1983
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"one factor is it was only 60% TPS at the emap crossover point, looks like you didn’t really roll into until the last 500 rpm or so"
finally had a chance to do another run.
i was able to go 100% TPS at 5200 and hold it as opposed to a choppy throttle in post 50.
choppy throttle crossover (emap/emp = to boost) was at 5687
crossover today with full throttle was at 5774
both were at 20 psi.
i had to end my run today at 6357 boost 20.0 backpressure 23.7
choppy throttle run at 6357 boost 20 backpressure 24.9
it doesn't appear throttle position effected crossover or backpressure.
i look forward to posting some higher rpm and boost numbers.
.
finally had a chance to do another run.
i was able to go 100% TPS at 5200 and hold it as opposed to a choppy throttle in post 50.
choppy throttle crossover (emap/emp = to boost) was at 5687
crossover today with full throttle was at 5774
both were at 20 psi.
i had to end my run today at 6357 boost 20.0 backpressure 23.7
choppy throttle run at 6357 boost 20 backpressure 24.9
it doesn't appear throttle position effected crossover or backpressure.
i look forward to posting some higher rpm and boost numbers.
.
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