Hmmm, interesting, I don't see how it peaks that early??? I haven't seen any data sheets, whether a 1600 or a 1700 that peaks that early, all have been 500 to 600rpm higher. I know my dyno guy asks what the rev limiter is, but he still cuts it off 100rpm below that for safe guards.

Are you using the stock ignition module or dyna? What yr bike? never mind, it's a 1700, I can tell by rear tail lights.

I can't find my old sheets, but when I see the guy next week, he should still have them on the computer, he said he didn't have a way to email them to me, didn't press the issue to transfer them to a thumb drive, so he could load it on home computer to send them to me. Maybe I'll take my drive with me so he could load them on there, if he's not too busy. But he'll probably will be slammed, this bike fest brings in about 100k bikes over the 3 day weekend.

Erbman02 wrote:
Hmmm, interesting, I don't see how it peaks that early??? I haven't seen any data sheets, whether a 1600 or a 1700 that peaks that early, all have been 500 to 600rpm higher. I know my dyno guy asks what the rev limiter is, but he still cuts it off 100rpm below that for safe guards.

Are you using the stock ignition module or dyna? What yr bike? never mind, it's a 1700, I can tell by rear tail lights.

I can't find my old sheets, but when I see the guy next week, he should still have them on the computer, he said he didn't have a way to email them to me, didn't press the issue to transfer them to a thumb drive, so he could load it on home computer to send them to me. Maybe I'll take my drive with me so he could load them on there, if he's not too busy. But he'll probably will be slammed, this bike fest brings in about 100k bikes over the 3 day weekend.

Look at the sheet trob posted his peaks around 4350 and straight lines to about 4600. Mine hits peak and don't hold as long . In relationship to time you would never notice. But I would also be curious why, or what could have been diff to change it. I do believe I'm at the point that to gain on one side I'll loose on the other.

davej wrote:


Look at the sheet trob posted his peaks around 4350 and straight lines to about 4600. Mine hits peak and don't hold as long . In relationship to time you would never notice. But I would also be curious why, or what could have been diff to change it. I do believe I'm at the point that to gain on one side I'll loose on the other.

Duration of tq is in the cam design, peak of tq is dependent on AFR. I know of a couple of cams that are regrinds, one is a mild version to be used with stock pistons which from what I have read will keep peak tq to approx 4600rpm, then there is a wild version , that are for HC pistons. But wild version for a 1600 engine would also require the heavier lifter springs, 1700's have the upgraded lifter springs and that is why also if using a Dyna3k you can set rev limit to 5500rpm, on a 1600 only to 5k rpm. If I had the bucks I would have gone with the mild grinds, the idea of being able to keep the tq and HP to the top would be awesome.

Where do these values come from and what is the effect of AFR on engine torque? The chart below provides some answers (ref: Automotive Handbook 2nd edition by Bosch GmbH, pp. 439). In the absence of other limiting factors, maximum engine torque occurs at about 13.5 AFR. Under wide open throttle (WOT) conditions, a richer mixture (12.5 to 12.8 AFR) is generally required to reduce cylinder head temperatures and avoid detonation. While the torque curve appears relatively flat from 12 to 14.7 AFR, the effect on cylinder head temperature is more pronounced. Please remember that the chart is based on lab experiments under carefully controlled conditions and with gasoline octane high enough to avoid limiting effects from detonation.

Engines with race camshafts exhibit large cyclical variations at idle - necessitating a relatively rich idle to prevent stalling.

Thats fine but we were talking Hp not Tq. Your question was about Hp peaking at 4250

When ya said this "I do believe I'm at the point that to gain on one side I'll loose on the other"

I thought you were referring gaining hp and losing tq or gaining tq and losing hp.

Hence my bringing up the tq, guess a bit of confusion on my part.
Was your run done in 4th gear or 5th?

To be honest with you I don't know what gear it was in. I do know, like yourself I like to play with diff set ups to find the one that fits me the best.

davej wrote:
To be honest with you I don't know what gear it was in. I do know, like yourself I like to play with diff set ups to find the one that fits me the best.

Just some thought here, and without going back to read all your posts an numbers again.
I know you mentioned you have the 180 main, you came down from the 182.5, and your wot AFR was 12.3? I'm just wondering if for some odd reason he did not get throttle past the point where all fuel is strictly off the main, and you are much richer than that AFR read, and slightly bogging the engine and losing HP? Your tq numbers are certainly there, but seems you can still get some hp. hmmmm

I wish over the yrs of collecting this data I would have copied and put them in some format to analyze, unfortunately it's only stored in my "gray" matter. lol In a way, I'm glad I did this much tinkering and doing all those runs, puts it all into perspective with fact, though it did cost, but at least I was capable to do my own tuning, the icing on the cake was finding that article that I have used for the past few yrs, and of course the 42 w/yost power tube/
.

BTW, I beat out a vette today, from a traffic light


Ok, ok, so it was only for the first five feet LOL I got the jump on him when light turned green

No,I said I'm at a 182.5 and could have probably gone to a 180. Going to a 180 might have given me a little kicker on the HP. I don't know and not ready to pay for another dyno to find out. At least for now.