My first time on a dyno
10-20-01, 09:23 PM
#4
Just Call Me Terminator!
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i know its auto, a little more driveline loss but that's only like a 20hp increase with your mods. i would expect a little higher but then again i've never seen an auto dyno chart. good job anyway for not blowing up on dyno that is important too 
10-20-01, 10:37 PM
#6
Yellow Dragon is no more
Ok, I am not trying to rip you .. but you have some MAJOR boost problems to address. Before the transition the torque curve is crazy and the boost spike @ the transistion is liable to pop your motor-quickly. You have the tools to dial that in so it is not a problem.
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10-20-01, 11:45 PM
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Originally posted by vosko
i know its auto, a little more driveline loss but that's only like a 20hp increase with your mods. i would expect a little higher but then again i've never seen an auto dyno chart. good job anyway for not blowing up on dyno that is important too
i know its auto, a little more driveline loss but that's only like a 20hp increase with your mods. i would expect a little higher but then again i've never seen an auto dyno chart. good job anyway for not blowing up on dyno that is important too
Nowhere near as bad as the guy who ran his car before me: His 3rd Gen has all the goodies - Haltech, Apex ball-bearing turbo, Apex big-*** FMIC, Dual N1 exhaust, downpipe, midpipe, etc. Something weird was going on with his because it sounded like it was running great but was only putting down 270HP. Something odd is going on with his ignition system.
And like Boostd 7 said, thats just the way it looks when it shifts (sure wish it woulda zoomed up to 270 and held though
- threw me for a loop too when I saw it.
10-21-01, 12:47 PM
#11
Not to mention the fact that you don't, or atleast most dyno shops don't hit the record button until you are in the gear you want for the run. Not just hit it when you start in first gear. Look at the 2nd bump, right at the 4500 transition. I've seen a couple of dyno runs by a third gen auto and they look nothing like that, except for the 2 humps that shouldn't be there. Its a boost spiking problem. Watching my friend's 3rd gen auto, he started in 2, went up to about 3500 rpms, put it up in 1, same shift into drive and hammered it. If he did the same, the 1st hump is when he hammered it in drive, boost spiking somewhat, then spiking again at transition.
Tim Benton
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10-21-01, 01:15 PM
#12
Yellow Dragon is no more
geezzz, now I am going to have to learn this ... it is just a little crazy. Do the autos switch turbos differently? I have seen nothing in the manual to indicate this .... but maybe I just missed it.
10-21-01, 04:17 PM
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No that is NOT turbo spike, it is shift shock just as stated earlier. that is exactly what mine looks like. I agree dyno pulls should be in one gear, but if it is in "D" then it will hit OD. Just like you wouldn't make a dyno run in 5th gear I think the auto's should be dyno'd in "S".
10-21-01, 04:22 PM
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Your dyno run looks a little off, there seems to be a boost spike. You might be right on your cat, try replacing it with a high flow cat or remove it and use an off road pipe. Does your FD has a boost gauge?
10-21-01, 07:13 PM
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I wasn't really gonna reply anymore because it sounded like this was getting argumentative.
If you look at the graph, you will see that at the bottom it says RPM and not time. If the graph was a measurement of what it did from a certain point in time to another point in time, then you would see the RPMs fall off after a shift was made - instead it records the peaks it sees at a certain RPM - regardless of when they happened. If someone has another description of what the dyno records, please lay it on me.
As for the funky squiggles between the two humps, those are being created by the boost. On the primary turbo I have something a little odd happening in that as its boosting in second gear it will fluctuate between 7&9 pounds. At transition it goes to 8 pounds and the when the secondary hits, it bounces to 11 for a half-second and drops and holds at 10. In my book, thats not a spike.
So should we have just recorded what it did in third gear? Probably. Is it in the past now? Yes.
On a side note, they found a couple of the Haltech's outputs wired up wrong on that other car I mentioned - now it flat out hauls ***. I rode in a T-78 car and this one felt like it pulled a hell of a lot harder. If someone is looking at a single turbo, I'd get the Apexi RX-6 - its just wicked.
If you look at the graph, you will see that at the bottom it says RPM and not time. If the graph was a measurement of what it did from a certain point in time to another point in time, then you would see the RPMs fall off after a shift was made - instead it records the peaks it sees at a certain RPM - regardless of when they happened. If someone has another description of what the dyno records, please lay it on me.
As for the funky squiggles between the two humps, those are being created by the boost. On the primary turbo I have something a little odd happening in that as its boosting in second gear it will fluctuate between 7&9 pounds. At transition it goes to 8 pounds and the when the secondary hits, it bounces to 11 for a half-second and drops and holds at 10. In my book, thats not a spike.
So should we have just recorded what it did in third gear? Probably. Is it in the past now? Yes.
On a side note, they found a couple of the Haltech's outputs wired up wrong on that other car I mentioned - now it flat out hauls ***. I rode in a T-78 car and this one felt like it pulled a hell of a lot harder. If someone is looking at a single turbo, I'd get the Apexi RX-6 - its just wicked.
10-21-01, 08:25 PM
#17
I haven't heard of shift shock, although I don't have an auto tranny car and although I have been to the dyno about 20 times with my car and numerous other times, only once with an auto was there. I never asked or heard of the term, so it's new to me. Glad to learn something new and can pass on that knowledge next time I see an auto tranny 3rd gen on the dyno and he/she wonders why the RWHP curve looks like that.
Tim Benton
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10-23-01, 12:46 AM
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Dynojet graphing explanation
Actually the shift shock??? is torque converter spike, just like you slipping your clutch in a manual - you know how the revs rise momentarily until it locks up. Since the Dynojet reads a spark signal from your plug wire (Trailing plug wire on a 7) and your tires are not slipping when the revs go up at shift the dyno "thinks" momentarily that you are making a different amount of power than you actually are - remember that it is simply doing the hp=(torque*rpm)/5250 to arrive at hp - so it blindly plots what it sees.
However in the graph posted the spike is the second turbo coming on line at around 4500 and the humps are due to the waste gate slowly - and stupidly - trying to control boost. In this graph it is not showing the shift spike. It cannot on a dynojet graph that is plotted by RPM. You can only show the shift spike in the middle of a run on a graph plotted by time or by mph and it does look very, very similar to the graph posted though. If the car had shifted it would then change gear ratios, and the dynojet plots all rpm graph by its calculated gear ratio. You cannot in the dynojet software plot two different gear ratios as one line in the same graph when you are plotting by rpm, only when plotting by time or mph. When you go to select a plot in the software it asks you to select which gear ratio you want to plot when asking for an rpm graph, you cannot select two ratios for the same run. You can put two different ratios from two different runs on the same graph but graph has one run legend at the top of the graph.
This is true no matter when the operator decides to begin sampling. Most times you sample at an rpm that is high enough that the car will not down shift if possible. If it does downshift its no big deal you just get a run with two gear ratios in it, and some big spikes from the converter locking up. But once again you could not plot this situation on a graph by rpm because it will represent two different gear ratios, and TWO DIFFERENT GEAR RATIOS WILL COVER THE SAME RPM POINTS, SECOND WILL REV TO REDLINE THEN SHIFT TO THIRD THAT WILL DO THE SAME SO THERE WOULD BE TWO DIFFERENT DATA LINES.
Winpep (the dyno software for dynojets) calculates the gear ratio you are running by using the known diameter of the drum on the dyno and does a calculation based on the rpm that are turning (from the rpm pickup attached to your plug wire) So, that is why it shows a spike with the rpm slip while the drum is spinning at the roughly same acceleration rate of the gear you just left.
This calculation of ratio is also why you can dyno with 13in wheels or 18in wheels and the rpm curve will plot the same, of course if you plotted by mph, the curve would be shifted to the left with the smaller wheels because your gear ratio changed so you made the same power earlier mile per hour wise, and on the street you would accelerate faster because of the ratio change, but on a rpm graph it would be identical if your wheel/tire combo of the 13's and 18's weighed about the same amount.
Think that spike is bad - you ought to see the torque converter spikes from big drag cars with big stalls in their torque converters...
I have a dynojet 248C running Winpep, a wide band 02, dynotrac and proportional air (dynojets version of loading capability), own an rx-7, run the thing every day (both of them) - so I am pretty sure on this.
Sorry for the long text...
Vince
However in the graph posted the spike is the second turbo coming on line at around 4500 and the humps are due to the waste gate slowly - and stupidly - trying to control boost. In this graph it is not showing the shift spike. It cannot on a dynojet graph that is plotted by RPM. You can only show the shift spike in the middle of a run on a graph plotted by time or by mph and it does look very, very similar to the graph posted though. If the car had shifted it would then change gear ratios, and the dynojet plots all rpm graph by its calculated gear ratio. You cannot in the dynojet software plot two different gear ratios as one line in the same graph when you are plotting by rpm, only when plotting by time or mph. When you go to select a plot in the software it asks you to select which gear ratio you want to plot when asking for an rpm graph, you cannot select two ratios for the same run. You can put two different ratios from two different runs on the same graph but graph has one run legend at the top of the graph.
This is true no matter when the operator decides to begin sampling. Most times you sample at an rpm that is high enough that the car will not down shift if possible. If it does downshift its no big deal you just get a run with two gear ratios in it, and some big spikes from the converter locking up. But once again you could not plot this situation on a graph by rpm because it will represent two different gear ratios, and TWO DIFFERENT GEAR RATIOS WILL COVER THE SAME RPM POINTS, SECOND WILL REV TO REDLINE THEN SHIFT TO THIRD THAT WILL DO THE SAME SO THERE WOULD BE TWO DIFFERENT DATA LINES.
Winpep (the dyno software for dynojets) calculates the gear ratio you are running by using the known diameter of the drum on the dyno and does a calculation based on the rpm that are turning (from the rpm pickup attached to your plug wire) So, that is why it shows a spike with the rpm slip while the drum is spinning at the roughly same acceleration rate of the gear you just left.
This calculation of ratio is also why you can dyno with 13in wheels or 18in wheels and the rpm curve will plot the same, of course if you plotted by mph, the curve would be shifted to the left with the smaller wheels because your gear ratio changed so you made the same power earlier mile per hour wise, and on the street you would accelerate faster because of the ratio change, but on a rpm graph it would be identical if your wheel/tire combo of the 13's and 18's weighed about the same amount.
Think that spike is bad - you ought to see the torque converter spikes from big drag cars with big stalls in their torque converters...
I have a dynojet 248C running Winpep, a wide band 02, dynotrac and proportional air (dynojets version of loading capability), own an rx-7, run the thing every day (both of them) - so I am pretty sure on this.
Sorry for the long text...
Vince
Last edited by silverseven; 10-23-01 at 12:49 AM.
10-23-01, 11:00 PM
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my bad, my dyno chart is plotted horsepower per MPH and not RPM. Looks identical though, and "shift shock" is how it was exlained to me. On my RPM chart Chris shifted the data to only read after the transition so that it would show an even pull and not be like viper jr's. Mine was really three runs on one graph to show hp gains with different mods, so any one run was not that big a deal to me. thanks for your explanation. BTW shift shock is mentioned in the shop manual. normally timing is reduced and a torque reduction signal sent by the PCM to minimize this during shifting. It's one of the things you lose by going to a PFC, so shift shock is magnified. Viper JR still has his PCM-AT so I would think his would be minimized. At any rate it's my new understanding that the graph shown doesn't represent any shift point at all, right?
Last edited by weaklink; 10-23-01 at 11:07 PM.
10-23-01, 11:42 PM
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dyno graph
Right, the graph posted does not have any shift spikes showing. And you are right, while graphing in winpep you can crop the graph to not display stuff like shift spikes. Usually since people like them plotted by rpm fi there is any shift spike showing it will be only at the very beginnig or very end of the graph in the rpm range, and it si very common practice to crop that out because is gives a false high reading for peak hp or torque.
Also as you probably know the hp and torque curves will always cross at 5250 rpm even on a run graphed by mph or time. It's a mathmatical function so they have to. It can be misleading in some graphs like the one posted because the scale on the x an y axis is not the same, so on that graph the runs look even odder (is that a word?) and almost shows torque following hp. I think it is a good idea to request your graphs with equal scales so your are looking a actual visually relative comparisons. For example just glancing at the graph posted it looks like hp and torque are about the same - when actually hp is a bit higher as you know on rotaries.
Car magazine always play with that kind of stuff and make 3 hp change look huge on their graphs because of the scales they choose.
Sometimes is does make sense to scale them completey differently - like an indy car that would make huge hp and much much less torque - to see any shape in the torque curve you would have to scale them like that.
Also as you probably know the hp and torque curves will always cross at 5250 rpm even on a run graphed by mph or time. It's a mathmatical function so they have to. It can be misleading in some graphs like the one posted because the scale on the x an y axis is not the same, so on that graph the runs look even odder (is that a word?) and almost shows torque following hp. I think it is a good idea to request your graphs with equal scales so your are looking a actual visually relative comparisons. For example just glancing at the graph posted it looks like hp and torque are about the same - when actually hp is a bit higher as you know on rotaries.
Car magazine always play with that kind of stuff and make 3 hp change look huge on their graphs because of the scales they choose.
Sometimes is does make sense to scale them completey differently - like an indy car that would make huge hp and much much less torque - to see any shape in the torque curve you would have to scale them like that.
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