1st Dyno run complete - analysis help
#1
Pro
Thread Starter
1st Dyno run complete - analysis help
I have completed my first dyno run with the 928 and was a bit surprised that the power registered this low, it certainly feels quick on the road. As least there is still plenty to come but why this low? 330hp / 290 lb/ft at the crank
I am noticing that the power is not dropping off at peak revs like other dyno print outs that I have seen, not sure if this points to cam timing - only thing coming to mind
S4 89
Standard capacity
Colins cams
928 motorsport merged headers
X pipe
Re mapped with ST and fairly happy with the mapping,
standard inlet manifold has been modified
I am noticing that the power is not dropping off at peak revs like other dyno print outs that I have seen, not sure if this points to cam timing - only thing coming to mind
S4 89
Standard capacity
Colins cams
928 motorsport merged headers
X pipe
Re mapped with ST and fairly happy with the mapping,
standard inlet manifold has been modified
Last edited by Marti; 04-10-2019 at 03:25 PM.
#3
Nordschleife Master
How did you set the camshafts? Have you done a compression test to see what the readings are bank to bank (done hot).
Are there any faults on the ignition monitoring tab? Does it show any retardation per cylinder in that tab?
A baseline of before you start is always good.
Also I cannot remember what valve springs did you use?
Most auto S4s put down between 260-270 whp which is where you are currently.
Are there any faults on the ignition monitoring tab? Does it show any retardation per cylinder in that tab?
A baseline of before you start is always good.
Also I cannot remember what valve springs did you use?
Most auto S4s put down between 260-270 whp which is where you are currently.
#5
Pro
Thread Starter
How did you set the camshafts? Cams set as per your instructions and checked several times with a 32vr tool.
Have you done a compression test to see what the readings are bank to bank (done hot). I have done while cold and cylinders were very close to each other. I could perform a hot CR test also?
Are there any faults on the ignition monitoring tab No, all good
Does it show any retardation per cylinder in that tab? No, ST has been done on both maps, igniting is taking a good amount of advance before knocking occurs. During the run I got a one knock under full load around 3k revs but that was all
A baseline of before you start is always good. I wish I had a baseline before. This run is to be the baseline before I start testing the new inlet manifold.
Also I cannot remember what valve springs did you use? I am using the new springs you supplied
Most auto S4s put down between 260-270 whp which is where you are currently.
Have you done a compression test to see what the readings are bank to bank (done hot). I have done while cold and cylinders were very close to each other. I could perform a hot CR test also?
Are there any faults on the ignition monitoring tab No, all good
Does it show any retardation per cylinder in that tab? No, ST has been done on both maps, igniting is taking a good amount of advance before knocking occurs. During the run I got a one knock under full load around 3k revs but that was all
A baseline of before you start is always good. I wish I had a baseline before. This run is to be the baseline before I start testing the new inlet manifold.
Also I cannot remember what valve springs did you use? I am using the new springs you supplied
Most auto S4s put down between 260-270 whp which is where you are currently.
The car does have a standard exhaust system, could that be holding it back?
#6
Pro
Thread Starter
Does the shape of the power curve point to anything anyone has seen before, Greg, Colin et al
what I am pointing out is that often the curve plateaus by say 5.5 and starts to drop off by around 6.2k where as this is still climbing at 6.5
what I am pointing out is that often the curve plateaus by say 5.5 and starts to drop off by around 6.2k where as this is still climbing at 6.5
#7
Pro
Thread Starter
I also posting up a further run below, this was the previous run to the final run above.
The difference between the two runs is actually I shifted the flappy opening from 3.4k revs to something like 3.8k revs on the final run after I saw the below effects of the flappy at 3.4k which was putting a hole in the power curve
I plan further dyno runs with a completely stock inlet manifold as a comparison between modified stock and standard stock. I am wondering why power is just climbing and not plateaued off
The difference between the two runs is actually I shifted the flappy opening from 3.4k revs to something like 3.8k revs on the final run after I saw the below effects of the flappy at 3.4k which was putting a hole in the power curve
I plan further dyno runs with a completely stock inlet manifold as a comparison between modified stock and standard stock. I am wondering why power is just climbing and not plateaued off
Last edited by Marti; 04-10-2019 at 04:56 PM.
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#8
Burning Brakes
stock exhaust ? that's where your loosing power . 32 RW HP with headers and a duel 2 1/2 exhaust . at 350+ I was loosing power with the injectors wide open . now with proper injectors , there is even more power . 290 was my base RWHP . 91 GT
#9
Administrator - "Tyson"
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His post says headers & X-pipe.
#11
Official Bay Area Patriot
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Random thought, could the diameter of the primaries on those headers be too small? I'm assuming a good set of headers for these cars use a 1 7/8" primary diameter, not 1 3/4".
Probably a question for both Marti and Colin, but for those cams, are you using stock injectors? Ideally, wouldn't a bigger injector benefit Colin's cams?
Probably a question for both Marti and Colin, but for those cams, are you using stock injectors? Ideally, wouldn't a bigger injector benefit Colin's cams?
#12
Pro
Thread Starter
Random thought, could the diameter of the primaries on those headers be too small? I'm assuming a good set of headers for these cars use a 1 7/8" primary diameter, not 1 3/4".
Probably a question for both Marti and Colin, but for those cams, are you using stock injectors? Ideally, wouldn't a bigger injector benefit Colin's cams?
Probably a question for both Marti and Colin, but for those cams, are you using stock injectors? Ideally, wouldn't a bigger injector benefit Colin's cams?
I forget the exact size of the header pipes but they are a good size and proven to increase power over stock.
#13
Official Bay Area Patriot
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I know there are cases where dynos can read power differently, sometimes understating. Typically it's calibration, but most (okay likely ALL) of the time these guys with dynamometers know what they're doing. Next thought is power rating - is it SAE???
In the end, the engine dyno is the most accurate, not a wheel dyno that attempts to calculate power loss through the drivetrain and back into the crank number.
In the end, the engine dyno is the most accurate, not a wheel dyno that attempts to calculate power loss through the drivetrain and back into the crank number.
#15
Rennlist Member
Random thought, could the diameter of the primaries on those headers be too small? I'm assuming a good set of headers for these cars use a 1 7/8" primary diameter, not 1 3/4".
Probably a question for both Marti and Colin, but for those cams, are you using stock injectors? Ideally, wouldn't a bigger injector benefit Colin's cams?
Probably a question for both Marti and Colin, but for those cams, are you using stock injectors? Ideally, wouldn't a bigger injector benefit Colin's cams?
AF chart with a dyno sheet is helpful in "How does this look" discussions.