ashills dyno graph
- Thread starter stevepudney
- Start date
Fusion Ed
Active Member
The turbo flow map actually goes upto 2.5 bar (3.5 absolute)
The only way to really see how happy a turbo is, is to measure the shaft RPM. Typically they will be spinning too fast when they start to choke up at the top end if really pushed hard. But There is nothing to suggest that this turbo is in anyway unhappy at all.
The only way to really see how happy a turbo is, is to measure the shaft RPM. Typically they will be spinning too fast when they start to choke up at the top end if really pushed hard. But There is nothing to suggest that this turbo is in anyway unhappy at all.
stumo
Active Member
what was the AFR at max power?
Assuming a BSFC of.55Lb/hr (average fuel consumption for a turbo motor)
Assuming the AFR is 12:1 (pretty rich but not too extreme)
The airflow needed to produce 463HP would be 51Lb/min
Looking on the chart, it would seem that at 2Bar (manifold pressure) the max output is in the region of 46-47Lb/min and this is running the turbo in a very inefficient area of the map.
If we use the max figure from the map (at the 2Bar manifold pressure as before) of 47Lb/min and the AFR of 12 then the max output would be 427hp.
A difference of 36hp.
Did the dyno operator “fiddle” the results (there are several ways that this can be done) cos somehow the figures don’t add up??????
(using an AFR of 11.5 and the BSCF of .58(due to lower AFR’s) will produce the same 51Lb/min airflow requirement )
Assuming a BSFC of.55Lb/hr (average fuel consumption for a turbo motor)
Assuming the AFR is 12:1 (pretty rich but not too extreme)
The airflow needed to produce 463HP would be 51Lb/min
Looking on the chart, it would seem that at 2Bar (manifold pressure) the max output is in the region of 46-47Lb/min and this is running the turbo in a very inefficient area of the map.
If we use the max figure from the map (at the 2Bar manifold pressure as before) of 47Lb/min and the AFR of 12 then the max output would be 427hp.
A difference of 36hp.
Did the dyno operator “fiddle” the results (there are several ways that this can be done) cos somehow the figures don’t add up??????
(using an AFR of 11.5 and the BSCF of .58(due to lower AFR’s) will produce the same 51Lb/min airflow requirement )
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nashgti-r
Guest
great results there allen. was quite shocked when i recieved a text saying that you got 460bhp running on standard cam and head lol.
looking forward to seeing this go now, jus hope you dont get rid before hand lol:lol:
looking forward to seeing this go now, jus hope you dont get rid before hand lol:lol:
Interesting result gents, I know this might appear negative but whichever way you cut it I think you're the first to try 2.0Bar on a 3071 with an R. I can't square a few corners in my head though.
Why does the boost come on so late? It reminds me of when I was running 1.8Bar on a standard elbow. After I swapped it to a 3" setup I was getting >80% torque from 3.5K but peak load went up 10% too.
If the turbo can't hold pressure to the redline then either the turbine has become a restriction or the compressor has choked.
I'd have expected at 2.0Bar the efficiency would start to drop, did you noticabley have to back off the ignition?
Cheers,
Jim
Why does the boost come on so late? It reminds me of when I was running 1.8Bar on a standard elbow. After I swapped it to a 3" setup I was getting >80% torque from 3.5K but peak load went up 10% too.
If the turbo can't hold pressure to the redline then either the turbine has become a restriction or the compressor has choked.
I'd have expected at 2.0Bar the efficiency would start to drop, did you noticabley have to back off the ignition?
Cheers,
Jim
Fusion Ed
Active Member
The dyno run has been completed in SHOOT_44 which is a standard dyno power run setting for 4wd turbo cars. Exactly the same as all other cars have been tested on this and other Dyno Dynamics Rolling roads. It does no one any favours to try and fiddle the results, least of all the reputation of the rolling road in question. (who are known as fairly conservative on their power figures)
Stumo, You took a random BSFC figure (and AFR for that matter) to calculate the lb/min of air required to make this much power, and only just came to the right of the choke line (after you had rounded up).
If you use 12:1 as in your example and alter the BSFC to 0.5 (which is quite possible on a 4vpc modern engine) then you are consuming 46lb/min of air, which is within the map shown above (even at 2 bar boost). 12:1 is not particularly a rich mixture when going for such power levels. In fact many engines will make more power by going slightly richer, very few slightly leaner. If you then assume that the AFR was richer, then again the lb/min of air required will further drop, now to around 44.8. The point I am making is your trying to discredit a power run on a marginal change in BSFC of as little as 3 which would put it on the compressor map, that is if to say it was off it in the first place. You have hardly proven that the results are totally impossible and must have required at least 60lb of air to achieve.
In fact there are so many variables that have been assumed here which could either way put it on or off the map (since of course Garrett rate the turbo to 475bhp, we are obviously close to the edge of the efficiency map) that it seems pointless to dispute something that could be so close one way or the other. Its unfortunate that the AE r/r day on Sunday is cancelled. In any case I am sure Allen would/will have been more than happy to do back to back comparisons when the next opportunity arises since the above graph is not enough for you. (that is of course unless he has sold it again!)
Finally Garrett kindly provide quite allot of detail on examples of the 3071 as used on a 2.0 engine: http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html
There is little point in repeating what is said there, however, my experience has shown to have got very similar results to the examples shown on that page.
Ed
Stumo, You took a random BSFC figure (and AFR for that matter) to calculate the lb/min of air required to make this much power, and only just came to the right of the choke line (after you had rounded up).
If you use 12:1 as in your example and alter the BSFC to 0.5 (which is quite possible on a 4vpc modern engine) then you are consuming 46lb/min of air, which is within the map shown above (even at 2 bar boost). 12:1 is not particularly a rich mixture when going for such power levels. In fact many engines will make more power by going slightly richer, very few slightly leaner. If you then assume that the AFR was richer, then again the lb/min of air required will further drop, now to around 44.8. The point I am making is your trying to discredit a power run on a marginal change in BSFC of as little as 3 which would put it on the compressor map, that is if to say it was off it in the first place. You have hardly proven that the results are totally impossible and must have required at least 60lb of air to achieve.
In fact there are so many variables that have been assumed here which could either way put it on or off the map (since of course Garrett rate the turbo to 475bhp, we are obviously close to the edge of the efficiency map) that it seems pointless to dispute something that could be so close one way or the other. Its unfortunate that the AE r/r day on Sunday is cancelled. In any case I am sure Allen would/will have been more than happy to do back to back comparisons when the next opportunity arises since the above graph is not enough for you. (that is of course unless he has sold it again!)
Good question actually. It seems that the response varies from car to car quite allot. Steve P GTi-R is a good example of one that responds very well. I believe Allens car may have a thicker head gasket, this again would work against its response slightly.
Not always. If you use a weak actuator (this car only has a 1 bar one iirc) the differential pressure on the pre to post turbine sides can force the waste gate open at higher boost levels. If Allen was to up the spring pre-load pressure I suspect that this will improve very noticeably.
Look at the map above. The turbo is capable of 2 bar to over 47.5 lb/min of air whilst still remaining on the map. Granted efficiency has dropped to below 70% but with the very cool intake temps of this week and an efficient HKS intercooler that's not a big deal. It MAY be that the turbo is close to its choke line, so of course will be causing more of a restriction, its not a big deal unless you want nothing more than high rpm power, at a result of less mid-range. Ignition advance is still plenty. I was still adding more and getting slightly more power but stopped once 460 was made. Interestingly these SR20s like to run quite a fair amount of advance when compared to other 2.0 engines I have mapped.
Finally Garrett kindly provide quite allot of detail on examples of the 3071 as used on a 2.0 engine: http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html
There is little point in repeating what is said there, however, my experience has shown to have got very similar results to the examples shown on that page.
Ed
the exhaust consists of the twin outlet elbow from the group buy but with a full 2.5" system next is to sort out is full 3" from elbow back to help breathing
with regards to fiddling figures the only variable in shoot 44 mode is to make inlet ambient temps higher than they really are the probe was on the front of car rather than under engine bay so no heat could affect the figures and make them better
shame the rolling road day was cancelled this week as would have put them all on a level base to be tested
with regards to fiddling figures the only variable in shoot 44 mode is to make inlet ambient temps higher than they really are the probe was on the front of car rather than under engine bay so no heat could affect the figures and make them better
shame the rolling road day was cancelled this week as would have put them all on a level base to be tested
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pulsarmick
Guest
Thats one fast gtir:-D that will shove it the evos lol 
what i was saying is i dont want to hit full boost at 5500 rpm, even if a 2871 wont give that power full boost at 5500, as thats way too laggy for me, my firends running a 3071 who edd mapped and my old m8 had a 28rs and on the road at reasonable boost id prffure the 28rs minimal lag full boost by 35 easy what i am saying i want a fast road car not a all or nothing car thats why im saying a gt2871 would have less lag and thats why im thinking about getting 1