Compressor Efficiency Problem
- Thread starter Killerbee
- Start date
..kind of hard to tell. I would guess that I have a 1/4" radius on the inside now. I also removed the molding flash where the sliders met.
After using the dreml I smoothed things out with 400 grit sandpaper.
Illustration of what I found to improve performance.
At all costs, air should not exceed 300 ft/s. I prefer 280 ft/s. It's not a magic number, but something to strive for. Above this, the resistance to flow quickly goes ballistic, decaying exponentially. The sharp bend makes this yet more critical. Here are some actual numbers, 700 cfm represents stock airflow.
That bend restricts diameter down to 2.4". By tooling like in the photo, you can make more like 2.6-2.7" effectively.
At all costs, air should not exceed 300 ft/s. I prefer 280 ft/s. It's not a magic number, but something to strive for. Above this, the resistance to flow quickly goes ballistic, decaying exponentially. The sharp bend makes this yet more critical. Here are some actual numbers, 700 cfm represents stock airflow.
That bend restricts diameter down to 2.4". By tooling like in the photo, you can make more like 2.6-2.7" effectively.
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when you can see through it, you've gone to far!
when you say inverted you mean it actually goes inside? and makes the bend almost smooth?
Almost filled up both inlet tubes, but not completely, I'm still working on removing material and smoothing the flow
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Larry, what is the material in the ports? I went back and ran some numbers on those ports as branch T's with no flow. It looks like 10% of the total loss would be found there. About .5-.7 psi at 67 lb/min (hot tune).
Compressor Efficiency
Hello Killerbee:
Thank you and everyone else for the very informative article.
Looking at the picture of the compressor tube that has had material removed to straighten out air flow, how much of a reduction in compressor/air heat would you expect to see with this much smoother flow?
I don't have access to flow meters or a flow bench, however the pictures and the informative articles are very helpfull and interesting.
My truck is a stock LLY 3500 series with an Edge with Attitude, EGR blocked and a sealed cold air intake which I use for towing a large 5th wheeel RV.
Anything that a person can do within reason to improve air and hopefully reduce temperatures will be a benefit.
Thank you to everyone and please keep the information flowing.
Hello Killerbee:
Thank you and everyone else for the very informative article.
Looking at the picture of the compressor tube that has had material removed to straighten out air flow, how much of a reduction in compressor/air heat would you expect to see with this much smoother flow?
I don't have access to flow meters or a flow bench, however the pictures and the informative articles are very helpfull and interesting.
My truck is a stock LLY 3500 series with an Edge with Attitude, EGR blocked and a sealed cold air intake which I use for towing a large 5th wheeel RV.
Anything that a person can do within reason to improve air and hopefully reduce temperatures will be a benefit.
Thank you to everyone and please keep the information flowing.
So far, I have fully plugged the pcv inlet with a milled piece of aluminum bar stock, the resonatar tube was plugged with an inverted pvc cap, both pressed in. Hopefully this smoothes out the air flow a little.
a significant amount, a 30 degree COT decrease at WOT, 50 lb/hr airflow (stock). That is approx 22,000 BTU/hr decrease.
There is a 2-4 psi exhaust manifold drive pressure decrease, and 50-100 lower EGT. MAF increases 7% also. Free air.
There should be some much larger gains with the redesign.
Side note, was looking at the neighbors CTD, his mouthpiece has twice the x-section, with a similar close bend.
I'll only be there for about 5 hours Lennart from about 8AM to 12ish- Just passing through on my way home from Russia! If your around there in the morning, maybe I can sneak through customs for a couple hours!!
That is a huge gain in heat KB - 22 000BTU is alot!! I imagine my LBZ could probably benefit a little from the same modifications as well. So there is an advantage to plugging those holes.
It seems Simon was partly right in removing the resonator over a year ago!!
I can't believe I just typed that!!
The compressor can easily output 200,000 BTU/hr stock boost, FWIW. If IAT runs away in a thermal feedback loop, it can go to 400,000. It is the nuts and bolts mechanism of the LLY overheat.
more pics after several hours of removing material
Do you have some comparison pictures Larry? Did you get a chance to take some pictures of the stock inlet vs. the one you've worked so hard on?
KB posted a before and after pic a few posts back that are pretty much identicle to mine. As soon as I pulled the old one from my motor, the new one went one, you know my track record with open holes in the motor
, so I didnt bother to take side by side pics.
The log I ran with the new inlet shows approximate 8 - 10 lbs more air than before on a WOT run........Mike will be posting the before and after logs since i don't know how :baby:
Seems like this was a good mod to do, and a really easy one at that as long as you take your time and dont remove too much material rendering your stock inlet unuseable
Seems like this was a good mod to do, and a really easy one at that as long as you take your time and dont remove too much material rendering your stock inlet unuseable
Here is Larry's data. I found sections to average that have the same approx rpm and boost, in order to compare MAF numbers. 61.5 lb/min vs 52.9 lb/min (stock). But note the air density is a little different on each, with IAT not held constant. This deemphasizes the disparity. The actual improvement, after correcting for ambient temp differences is probably closer to 5 lb/min. But hey, that is still 10% more air for free. It is consistent with what I am seeing. I am estimating that a redesigned mouthpiece will go 20% minimum.
That is the same as a new $2500 turbo.
That is the same as a new $2500 turbo.
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Here is Larry's data. I found sections to average that have the same approx rpm and boost, in order to compare MAF numbers. 61.5 lb/min vs 52.9 lb/min (stock). But note the air density is a little different on each, with IAT not held constant. This deemphasizes the disparity. The actual improvement, after correcting for ambient temp differences is probably closer to 5 lb/min. But hey, that is still 10% more air for free. It is consistent with what I am seeing. I am estimating that a redesigned mouthpiece will go 20% minimum.
That is the same as a new $2500 turbo.
I would like to add that this improvement is made with the same fueling, no extra fuel has been added just yet. More tests to come, I'll look back for some logs that show closer IAT's. Thanks Larry for giving this a shot.
The screen shots above are not really comparable, in the 2nd screen shot where the improvement can be seen, the screen shot is too far into the log and actually of one of the dsp tunes........I did an initial WOT with the base tune then several other smaller runs "not from a stop" in varias dsp tunes to see the difference while driving.
To compare apples to apples I think we need to compare the log from the start of the run since the other screen shot is of the base tune in question. Just from a quick glance at the 2nd screen shot, that is actually my smoke tune on the dsp switch.
To compare apples to apples I think we need to compare the log from the start of the run since the other screen shot is of the base tune in question. Just from a quick glance at the 2nd screen shot, that is actually my smoke tune on the dsp switch.
I don't really feel that it matters Larry. If MAP and RPM (and IAT) are the same, then MAF can be directly compared.
It is by no means scientific, with all the changing parameters, shifting, etc but it is very obvious to me now. This piece, all by itself, completely dogs the VGT and the LLY.
It is by no means scientific, with all the changing parameters, shifting, etc but it is very obvious to me now. This piece, all by itself, completely dogs the VGT and the LLY.
