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Discussion starter · #21 ·
Even more interesting, unless it's a typo, check out the torque on Gary's boxer compared to his horse power. I read the graph myself and saw the HP at 260 so I know that is correct. Usually the torque is less than the HP on an engine that is over-square, (larger bore than stroke).

Caleb's 308 had pretty high torque numbers also.

DJ
 
Spasso said:
Usually the torque is less than the HP on an engine that is over-square, (larger bore than stroke).
Are those torque figures the MAX TORQUE produced somewhere in the rev-range or the torque AT MAX HP? If the latter, I would expect the hp:torque ratio to mainly relate to the rpm number. That is, the higher-revving motor (at max bhp) will have a higher hp:torque ratio, as all else being equal, volumetric efficiency (& torque) is going to decrease at the higher revs.

Historically, over-square engines tend to run a higher rpm at peak-hp, but not always. My 2c worth :)
 
Discussion starter · #23 ·
4kid$,
Thanks for rattling my cage on the torque curve. Just wasn't thinking clearly. Yes, the torque figure is the max 'somewhere' in the curve and not directly related to the max HP figure.

The max torque actually occured about 1200 RPM lower than the max horse power figure on my 308 if I remember correctly.
DJ
 
That's interesting DJ, with torque peak that high there'd be no question of considering changing gear early - it's just all the way to the redline each time. I like it!! :D :D

(ps: I just got around to posting the hp vs torque eqns on another thread, FYI)
 
Discussion starter · #25 ·
Actually 4 Kid$, You are correct. Short shifting would have been prudent for the sake of the engine.
I found that instead of shifting at 7700 redline I was getting the same results shifting just above the END of the max HP range of 7000 RPM. I even shifted at 8000 RPM which resulted in just flogging the engine. You can see by the graph that max HP was about 6400 RPM falling off gradually to 7000 and the max torque was around 5200 RPM.

I was gaining 3 to 4 HP per run so I wasn't sure where the 'sweet spot' was.

This is the Max HP and Air/Fuel graph and the Max HP and Torque graph.
 

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That's even more interesting DJ! What I said isn't really correct as you look to have a redline significantly higher than the hp peak. As you say, going all the way until the needle bends is probably not going to give you the optimum performance.

To get it 100% you'd have to plot geared-torque curves for each gear on the same graph and see where the next-higher gear's torque becomes greater than the lower gear.

We must get our white lab-coats on! :green:
 
Discussion starter · #27 ·
Some of the guys were doing full throttle acceleration through all of the gears including OD while on the dyno to plot just what you suggested. The test indicated max HP developed through gearing put everybody well above 210 HP at the rear wheels.

It has been my experience through the years that Redline on most engines does not neccessarily mean that is the RPM at which the engine produces the most HP but is there to indicate maximum recommended operating design parameters. With that in mind I am not sure which part of your statement was incorrect.

I think what you were saying was the max HP and or torque was dependant on gearing as well. I know from looking at other charts that the max HP and torque figures were in a different RPM range from gear to gear.

Does that sound correct?

DJ
 
Discussion starter · #28 ·
I just read your other post about HP and Torque crossing each other at 5250 RPMS. I was unaware of the mathamatical tie between the two. I assumed the HP and Torque curves were dictated by bore and stroke relationships and that the intersection of the two would change as those two factors changed, (bore and stroke). This gleaned from articles of V8 hop-ups and changes made to the same engine on the same dyno over the course 1 or 2 pulls per modification, 10 to 12 pulls total..

My posted HP/Torque graph appears to support your numbers.

Am I understanding this correctly?

DJ
 
WoW!!! That is really nice! Is your's the fiberglass body? Either way, she is beeeeaauteeful! :D
 
Nice yellow 308. It is old but in good condtion you think? I doo. It must run good still, It's a Ferrari and they have power forever. :eek:ha:
 
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