444cu inch?

Smokem said:
Are you confusing dwell time with piston speed?
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The articles considered the speed discretely around dwell time so to speak so kind of one in the same (has been about 5-6 years atleast when I followed the competition). With regards to those higher compression pump gas motors the piston traveling away from dwell and not resting still at dwell for long was of high concern to reduce cylinder pressure at that instance hence reducing knock/detonation. I could not tell you in degrees what they considered dwell as I have already volunteered I am no expert. I am just interested in understanding the difference and connecting the dots.
 
Smokem said:
Depends on the stroke vs rod length.
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Yeah, that makes good sense now that I think of it. As you said I suppose it depends on the range of stroke/rod length we are talking about and the stroke of these cummins motors is far more than the small blocks they were using during the competition. I believe 4.125" was about as big of a stroke used.
 
I should have added it was regarding RPM, with the longer stroke/shorter rod the engine RPM will decrease. If the RPM was constant, then yes the shorter rod would decrease dwell time.
 
NickTF said:
Yeah, that makes good sense now that I think of it. As you said I suppose it depends on the range of stroke/rod length we are talking about and the stroke of these cummins motors is far more than the small blocks they were using during the competition. I believe 4.125" was about as big of a stroke used.
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Smokem said:
I should have added it was regarding RPM, with the longer stroke/shorter rod the engine RPM will decrease. If the RPM was constant, then yes the shorter rod would decrease dwell time.
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I see. I suppose then regardless of the stroke being discussed if rpm is constant dwell time decreases with less rod length for the given stroke.

(fixed: should have been length not angle)
 
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Yes, my comparison took into account the drop in effective RPM range. At lower RPM the higher rod angle also increases port velocity, increasing displacement at a higher rate regarding crank rotation.
 
Smokem said:
Yes, my comparison took into account the drop in effective RPM range. At lower RPM the higher rod angle also increases port velocity, increasing displacement at a higher rate regarding crank rotation.
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Yep, exactly. The shorter rod motors liked more CSA in the head at the same displacement and same rpm range as the longer rod counterpart.
 
Pretty simply diesel fuel burns slowly, to run high RPM you need to lead it with a great amount of static timing, or increase pressure to promote ignition and burn(CR advantage). I think more time will be spent decreasing engine speed, trying to promote ignition/burn by reaching more oxygen in the cylinder to reduce the crutch of static timing, in pulling applications anyway.
 
Weston at what speed do you think is the happy medium of speed but still able to burn most of the fuel your injecting?
 
The small loss of piston dwell was discussed before we destroked our engine, but just as before, it cleans up 100% now. The only dowside I've seen so far is that we cant run as much duration. I will build all my engines in this configuration now until I see a reason not to. Although, if I had deep pockets, I would love to see what a 450+ci motor would do on the track.
 
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