Revised interpretation of dyno results...
Discussion
I got my 1996 RT-10 dyno'd in Aberdeen on Saturday. The figures (flywheel) were 490 hp and 499 ft lbs torque. Initially I was reasonably happy with these numbers but after some research I'm not so sure. The car had about $15k worth of mods carried out in the US. These were:
Corsa exhaust
High-flow cats
Bellanger headers
T+D roller rockers
smoothe tubes
'stage 3' head work
enlarged throttle bodies
cam
lightened flywheel
3.54 gears
I now think that given all this work the flywheel figures should be at least a good 10% more than they are. In fact, the numbers I got would be appropriate for the level of tune that I bought the car in (with exhaust, cats, headers, roller rockers and smoothe tubes). I got the subsequent mods done immediately prior to importing the car back to the UK and the tuner said he never had time to dyno the car after the work had been done. Any advice on how to trouble-shoot what might be the problem would be greatly appreciated! Cheers.
Sorry, I don't have an electronic version of the dyno print-out right now. But there didn't seem to any malfunctions with the rolling road (there were quite a few other people there getting their cars done at the same time). I haven't had the ECU tweaked but the tuner said that for the modifications done the standard ECU set-up will 'learn' an appropriate tune. I was also told that standard fuelling system (pump and injectors) would be okay for the work done. Certainly the A/F ratio was pretty good throughout the run (slightly lean if anything). Also, 'the Viper is a speed density system, not a mass air system. A VE table and MAP sensor' - taken from VCA board! Cheers.
Edited by ViperScot on Wednesday 18th April 17:28
Do you have a RR report from the same place, before all the mods ? and performed under the same conditions ?
if not, then just go to a rolling road that is known for giving out high numbers if that is what is important to you.
All RR figures, especially flywheel guesstimations need to be taken with a picn of salt.
If you were talking before and after tuning results on the same day, then the gains achieved would be very valid.
But when simply looking for a figure to throw about in the pub....well...RR's are only useful for that if they tend to read high.
RR's that either read low, or even slightly close to realistic, tend to dissappoint the cars owners.
Doesnt really mean anything about the cars performance though.
if not, then just go to a rolling road that is known for giving out high numbers if that is what is important to you.
All RR figures, especially flywheel guesstimations need to be taken with a picn of salt.
If you were talking before and after tuning results on the same day, then the gains achieved would be very valid.
But when simply looking for a figure to throw about in the pub....well...RR's are only useful for that if they tend to read high.
RR's that either read low, or even slightly close to realistic, tend to dissappoint the cars owners.
Doesnt really mean anything about the cars performance though.
No, I'm not concerned about the numbers per se, more that there might be something wrong with the car or that the tuning work may not have been done properly. As it stands the car would appear to be at least 10% down on what I've been quoted for the extra mods I got done and far more in line with the level of tune I had when I bought the car. I'll let you read between the lines as to what I'm paranoid about...
Edited by ViperScot on Wednesday 18th April 23:57
ViperScot said:
No, I'm not concerned about the numbers per se, more that there might be something wrong with the car or that the tuning work may not have been done properly. As it stands the car would appear to be at least 10% down on what I've been quoted for the extra mods I got done and far more in line with the level of tune I had when I bought the car. I'll let you read between the lines as to what I'm paranoid about...
Edited by ViperScot on Wednesday 18th April 23:57
So if you had went to rollers, that showed you had say 550bhp or even 600bhp, would you be happy and think the car is great ?
stevieturbo said:
ViperScot said:
No, I'm not concerned about the numbers per se, more that there might be something wrong with the car or that the tuning work may not have been done properly. As it stands the car would appear to be at least 10% down on what I've been quoted for the extra mods I got done and far more in line with the level of tune I had when I bought the car. I'll let you read between the lines as to what I'm paranoid about...
Edited by ViperScot on Wednesday 18th April 23:57
So if you had went to rollers, that showed you had say 550bhp or even 600bhp, would you be happy and think the car is great ?
Tubby Steve,
Wind your neck in. What's with the self-righteous attitude? What more justified use of a rolling road is there than seeing if you're car's running right? Short of taking the car to a drag strip (of which there's a distinct lack of up here) and looking at terminal speeds, I've no way of quantifying if my car's putting the power out that it should after I shelled out $10k on mods.
ViperScot said:
stevieturbo said:
ViperScot said:
No, I'm not concerned about the numbers per se, more that there might be something wrong with the car or that the tuning work may not have been done properly. As it stands the car would appear to be at least 10% down on what I've been quoted for the extra mods I got done and far more in line with the level of tune I had when I bought the car. I'll let you read between the lines as to what I'm paranoid about...
Edited by ViperScot on Wednesday 18th April 23:57
So if you had went to rollers, that showed you had say 550bhp or even 600bhp, would you be happy and think the car is great ?
Tubby Steve,
Wind your neck in. What's with the self-righteous attitude? What more justified use of a rolling road is there than seeing if you're car's running right? Short of taking the car to a drag strip (of which there's a distinct lack of up here) and looking at terminal speeds, I've no way of quantifying if my car's putting the power out that it should after I shelled out $10k on mods.
ViperScot said:
No, I'm not concerned about the numbers per se, more that there might be something wrong with the car or that the tuning work may not have been done properly. As it stands the car would appear to be at least 10% down on what I've been quoted for the extra mods I got done and far more in line with the level of tune I had when I bought the car. I'll let you read between the lines as to what I'm paranoid about...
Self righteous ?? try a common sense or realistic approach..
You say you arent concerned about the numbers, yet you feel your car is not performing as it should based on those numbers. If I cant read between the lines, please explain to me what the problem is ?
A rolling road is tool for tuning first and foremost. Its niche, is for gauging before and after power/torque outputs mainly during a tuning sessions, where actual gains can be proven. That is were its results will be reliable.
Did you ever have your car tested at these same rollers when it was standard, under similar weather conditions etc ?
Despite the potential time difference between the 2 dates...that would at least give you a fairly solid baseline from which to work from.
Unless the rollers have a consistent reputation for either low, normal, or high outputs, a single trip to a rolling road, is almost a pointless exercise in determining how a car is performing.
What sort of reputation do these rollers have for numbers ? What were the wheel HP figures ( which tend to be more realistic, as it wont involve guessing flywheel numbers, which quite a few rollers simply do )
Years ago, I seen my own car make 280bhp on a set of rollers, yet the following day run 12.5 @ 120mph... Which is impossible. I know the rollers werent reading correctly though, so it was of little concern.
Ive heard of people driving to several sets of rollers in a day or 2, and variations of as much as 80bhp, and thats only on a car with say high 200's !!!!
So which is correct ? the one that says 220bhp, or 300bhp ?
If you went to the 220bhp rollers, is the car not performing as it should ? or if you went to the 300bhp rollers, would you be exstatic at the cars blistering show of power ?
To follow on that you might feel there is something wrong with the car due to it not making the numbers you feel it should...
You obviously took the time to go to the tollers. Did the RR operator have any thoughts on the matter ? How was the car fuelling ? Did they have any concerns about how it was performing or feel that it should have made more power ?
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