Keep in mind I was 400lbs heavier and on a chip and it was hot as hell that day and .03 slower in 60'. I used the e-brake and most often left at 15-20psi
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Taking a Stock Engine with Stock Turbo to the limit....
- Thread starter murphster
- Start date
Keep in mind I was 400lbs heavier and on a chip and it was hot as hell that day and .03 slower in 60'. I used the e-brake and most often left at 15-20psi
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Only thing he posted was a 26" tall slick. With growth could be close to 27". I'm on 28" drag radials with minimal growth.
As far as my current gearing, the guess was maybe since my car was lighter I can still get it out of the hole good on the 28"s and 3.23s and the tall gearing would help the whole run keeping the rpms way below 5000. I think it worked out pretty good. So would different gearing help me get out the hole better and give me a better ET even if the mph drops some? Or would a tighter converter work better? The only drawback with a tight converter or lockup converter could be that the load in 3rd with the 28"s and 3.23s could start to get too much and bog it down. I could switch to 27" tall tires and see what happens. Even 26" tires. Might have to try some different things.....
The guess is beyond good your doing great
since we are guessing
my guess would be to go with a more aggressive gear and keep the rollout of the pro should also tighten the converter on its own as well.dropping the tire size would give you the gear advantage to increase wheel speed but you would lose the sidewall and rollout.Ed was on a 26.0 x10.5 slick they def grow but so do the radials just not as much.
Finally got the turbo outlet pressure sensor working, sensor was dead. Also wired up the two EGTs I had pre and post IC to my XFI EGT module. Was able to go out and get some data yesterday. The turbo psi sensor was checked for calibration and reads correctly. Was within 0.5psi of my old sensor and corrected that. Also need a new fuel pressure sensor, my SSI one finally died after many years, my Fuel PSI does not read correctly.
EGTs seem to read about 30 degrees low, I have no idea why. I have an EGT meter that I need to plug them into to compare to XFI readings. Can also swap them with each other if needed to see if I get the same readings. Either way, they will be useful for relative readings rather than absolute temp... like if i tried a different intercooler, different turbo, different boost, hot vs cold weather, etc..
So here is the data on a street pull, EGT #7 is pre IC and #8 is post IC:
EGTs seem to read about 30 degrees low, I have no idea why. I have an EGT meter that I need to plug them into to compare to XFI readings. Can also swap them with each other if needed to see if I get the same readings. Either way, they will be useful for relative readings rather than absolute temp... like if i tried a different intercooler, different turbo, different boost, hot vs cold weather, etc..
So here is the data on a street pull, EGT #7 is pre IC and #8 is post IC:
I didn't get a chance to comment much on the data yesterday....
If you compare the Turbo PSI to the MAP PSI its 23.0 vs 21.7 at the end of the run, a difference of 1.3 psi. Looking at the average data for the whole pull I am losing about 1.5psi boost from the outlet of the turbo to the map sensor in the plenum. So this is for the IC plus all the pipes etc. Not very much at all. Ideally I would compare just pre and post IC boost but this is still very good data to know. I wonder how much is through the IC itself and how much is from all the pipes, etc. It would be great to compare to a dutt neck stock IC that is common for stock setups to see what the pressure loss is and if it stays constant throughout a pull and at different levels of boost.
The other great data is the delta EGT temp pre IC vs post IC. I'm cooling down 208 degrees through the FMIC at the end of the pull based on the different EGT temps between EGT #8 and #7. As a doublecheck, I can get a close calculation to what increase in air temps I should be seeing from my turbo using calculations from here: http://www.gnttype.org/techarea/turbo/turboflow.html. At 70 degree air temp and 23psi and 70% efficiency it says I should be seeing about 292 degrees out of my turbo, or an increase of 222 degrees over ambient out of my turbo. My FMIC is cooling the air down 208 degrees based on the EGT difference, meaning the air coming out of the IC should be only 14 degrees hotter than ambient, or around 84 degrees. If you add 30 degrees to my EGT readings all the numbers seem to agree.
What I take from this is that my IC is doing a good job. And its a starting point to compare if I make any changes like different boost, different weather, etc. Also would be great to compare to other ICs and turbos.
It also tells me that based on my inlet air temp of 69 degrees in the plenum, my alky benefit is probably mainly as a fuel and in cylinder cooling and octane versus cooling the air charge. On a stock IC I assume the air would be a lot hotter coming out of the IC and the air charge cooling of alky would play a lot larger role.
If you compare the Turbo PSI to the MAP PSI its 23.0 vs 21.7 at the end of the run, a difference of 1.3 psi. Looking at the average data for the whole pull I am losing about 1.5psi boost from the outlet of the turbo to the map sensor in the plenum. So this is for the IC plus all the pipes etc. Not very much at all. Ideally I would compare just pre and post IC boost but this is still very good data to know. I wonder how much is through the IC itself and how much is from all the pipes, etc. It would be great to compare to a dutt neck stock IC that is common for stock setups to see what the pressure loss is and if it stays constant throughout a pull and at different levels of boost.
The other great data is the delta EGT temp pre IC vs post IC. I'm cooling down 208 degrees through the FMIC at the end of the pull based on the different EGT temps between EGT #8 and #7. As a doublecheck, I can get a close calculation to what increase in air temps I should be seeing from my turbo using calculations from here: http://www.gnttype.org/techarea/turbo/turboflow.html. At 70 degree air temp and 23psi and 70% efficiency it says I should be seeing about 292 degrees out of my turbo, or an increase of 222 degrees over ambient out of my turbo. My FMIC is cooling the air down 208 degrees based on the EGT difference, meaning the air coming out of the IC should be only 14 degrees hotter than ambient, or around 84 degrees. If you add 30 degrees to my EGT readings all the numbers seem to agree.
What I take from this is that my IC is doing a good job. And its a starting point to compare if I make any changes like different boost, different weather, etc. Also would be great to compare to other ICs and turbos.
It also tells me that based on my inlet air temp of 69 degrees in the plenum, my alky benefit is probably mainly as a fuel and in cylinder cooling and octane versus cooling the air charge. On a stock IC I assume the air would be a lot hotter coming out of the IC and the air charge cooling of alky would play a lot larger role.
I noticed the IC temps & was impressed. Would you mind identifying the IC again?
I also noticed the "Backpress PSI" reading of: 46.6
Is that 46.6 PSI between exhaust valve & turbine inlet? If so, is that a high pressure, or fairly common for turbocharged engines?
Thank you.
I also noticed the "Backpress PSI" reading of: 46.6
Is that 46.6 PSI between exhaust valve & turbine inlet? If so, is that a high pressure, or fairly common for turbocharged engines?
Thank you.
Yes that would be the pressure prior to the turbine inlet. once you start hitting the 2:1 range boost to back pressure the turbo is about done.
Wow!
Most of my engine experience/knowledge is naturally aspirated engines. I have been fascinated with exhaust design & the attempts to maximize any scavenging effect to reduce pumping losses & increase cylinder filling ever since I first learned of the concept at about 12-13 years old. Have often heard of the intake & exhaust valve overlap period referred to as the "Fifth Cycle".
46.6 PSI sure seems like one hell of a piston pumping loss.
Most of my engine experience/knowledge is naturally aspirated engines. I have been fascinated with exhaust design & the attempts to maximize any scavenging effect to reduce pumping losses & increase cylinder filling ever since I first learned of the concept at about 12-13 years old. Have often heard of the intake & exhaust valve overlap period referred to as the "Fifth Cycle".
46.6 PSI sure seems like one hell of a piston pumping loss.
Its a Cottons front mount intercooler
Seems like the ratios of backpressure to manifold boost can range from a little over 1:1 for large efficient turbo setups to over 2:1 for small turbos. I would assume 40+ backpressure is pretty common.
These are numbers from my other engine with a larger turbo through the same exhaust: http://www.turbobuick.com/threads/backpressure-data-from-track-rental.439799/
So I made a full pass at the same boost and got some EGT readings at the end of the run... wow.
While #8 seems to read about 30 low I need to verify #7 temp. Either way, to get this turbo outlet temp at 23lbs boost at 80 degrees ambient means I'm somewhere in the low to mid 50s turbo efficiency. Damn.
While #8 seems to read about 30 low I need to verify #7 temp. Either way, to get this turbo outlet temp at 23lbs boost at 80 degrees ambient means I'm somewhere in the low to mid 50s turbo efficiency. Damn.
So running some more numbers.... I figure I'm somewhere around 375 rwhp give or take, and say somewhere between 410-420 crank hp. Turbos will generate somewhere between 9.5-10.5 hp per lb/min of air. So a little math says I could be flowing somewhere between 39-44 lb/min. If you use that for a turbo compressor map and look up the lb/min..
I am running 23psi boost out of the turbo before the IC. Pretty close to the 2.6 ratio listed ( actually 2.56). So 39-44 lbs/min at 2.6 would be at the top right off the graph. This could easily be 60% efficient or dip into the 50%s. The stated max flow of 37lbs/min would only give me a max of 388.5 crank hp, which seems too low to run the mph I am running but could be close. 38lbs/min seems to agree more. This would probably put me somewhere in the low 60% efficiency.
One other thing to note.... I am not monitoring air temp in the turbo inlet MAF pipe. I could be sucking in some hot air. If I was sucking in 100F instead of 80F, 63% turbo efficiency would give me the 360 degree turbo outlet temp that #7 EGT reads. #7 EGT could actually be correct and not off 30 degrees like #7 EGT. If I monitor the inlet air temp and verify the EGT #7 calibration this could give me a better idea of exactly what my turbo efficiency is. But me sucking in hotter air than ambient definitely makes the numbers agree more.
Was thinking of lowering the boost 1psi and seeing how the car responds with the EGT readings. Maybe some kind of cold air setup too.
I am running 23psi boost out of the turbo before the IC. Pretty close to the 2.6 ratio listed ( actually 2.56). So 39-44 lbs/min at 2.6 would be at the top right off the graph. This could easily be 60% efficient or dip into the 50%s. The stated max flow of 37lbs/min would only give me a max of 388.5 crank hp, which seems too low to run the mph I am running but could be close. 38lbs/min seems to agree more. This would probably put me somewhere in the low 60% efficiency.
One other thing to note.... I am not monitoring air temp in the turbo inlet MAF pipe. I could be sucking in some hot air. If I was sucking in 100F instead of 80F, 63% turbo efficiency would give me the 360 degree turbo outlet temp that #7 EGT reads. #7 EGT could actually be correct and not off 30 degrees like #7 EGT. If I monitor the inlet air temp and verify the EGT #7 calibration this could give me a better idea of exactly what my turbo efficiency is. But me sucking in hotter air than ambient definitely makes the numbers agree more.
Was thinking of lowering the boost 1psi and seeing how the car responds with the EGT readings. Maybe some kind of cold air setup too.
Checked the EGT calibration yesterday with car cold. Both were reading the same temp and only 9 degrees low. That means I'm around 55% turbo efficiency if the turbo was sucking in close to ambient air temp. Could be closer to 60% if I was sucking in air hotter than ambient.
I took out the driver's side high beam headlight assembly to see if it will bring in cooler air. Filter is right behind the headlights attached to a 4" MAF pipe. We'll see if it makes any difference.
I took out the driver's side high beam headlight assembly to see if it will bring in cooler air. Filter is right behind the headlights attached to a 4" MAF pipe. We'll see if it makes any difference.
I went with an M5. Could get an M1 if I wanted. I did some research on what others have used and it seemed reasonable. Some people use a lot bigger pre turbo. Might not make a difference, or it might. We'll see.
All I really want is to see if I can get a little more out of the stock turbo. Mainly trying to simulate running in cold weather. If it makes it flow a little more like I've read it can that will be great. I would only try this to get more out maxed out turbo. I could easily go faster by upgrading the turbo but thats not my goal. It was easy to hook up and it will be easy to undo.
All I really want is to see if I can get a little more out of the stock turbo. Mainly trying to simulate running in cold weather. If it makes it flow a little more like I've read it can that will be great. I would only try this to get more out maxed out turbo. I could easily go faster by upgrading the turbo but thats not my goal. It was easy to hook up and it will be easy to undo.
20psiofevil
Active Member
- Joined
- Feb 10, 2013
I have thought about spraying pre compressor for a long time just never plumbed the system. Interested in seeing your results!
The Granny
Active Member
- Joined
- Sep 30, 2015
How come you have your alky pressure transducer just before the nozzle? I have mine just after the filter, I thought that'd be the correct spot for it. My thinking was the pressure drop from the pump to the nozzle with lines as short as ours couldn't be that much
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