428 ft-lb RW torque at 4400 RPM, 408 RWHP at 5400 RPM
01-03-2008, 08:48 PM
#1
Race Director
Thread Starter
428 ft-lb RW torque at 4400 RPM, 408 RWHP at 5400 RPM
Through mufflers and full exhaust.
The 1 5/8" primary headers are choking the engine over 5500 RPM, but OTOH, they are giving me 400 ft-lbs torque from 3000 to 5400 RPM.
300 ft-lbs at 2000 RPM, 370 ft-lbs at 2500 RPM.
I will scan and post the graphs later.
Doug
The 1 5/8" primary headers are choking the engine over 5500 RPM, but OTOH, they are giving me 400 ft-lbs torque from 3000 to 5400 RPM.
300 ft-lbs at 2000 RPM, 370 ft-lbs at 2500 RPM.
I will scan and post the graphs later.
Doug
01-03-2008, 09:04 PM
#3
Race Director
Thread Starter
This was the 427 small block for anyone who came in late.
The 90% torque band is from 2100 to 5800 RPM.
Now THAT is a flat torque curve.
Doug
The 90% torque band is from 2100 to 5800 RPM.
Now THAT is a flat torque curve.
Doug
01-03-2008, 10:00 PM
#4
Le Mans Master
The 1 5/8" primary headers are choking the engine over 5500 RPM, but OTOH, they are giving me 400 ft-lbs torque from 3000 to 5400 RPM.
Congratulations on those numbers in street trim...... good luck with your rear tires
Doug
01-03-2008, 11:59 PM
#7
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2020 C2 of the Year - Modified Winner
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There's a deep 11 sec run for sure!!
Great job!
JIM
Great job!
JIM
01-04-2008, 01:15 AM
#8
Race Director
Thread Starter
Here is the dyno chart
Also note the actual spark advance numbers underneath the chart.
200 ft-lb of torque at idle, BTW.
Note the anomoly that starts about 2200 RPM, where power/torque suddenly drops, then takes a while to recover.
This was noticed on the 327 motor also, though on the 327 motor, it started about 400 RPM higher, there is obviously something either in the intake, or exhaust that is causing a reversion, or something, in that RPM range. I would suspect exhaust, as higher cubes = more air flow, thus a lower RPM at which it started.
The final WOT spark curve was
800 RPM 16 degrees
1200 19
2000 21
2400 22.5
2600 23.2
everything above 2600 was 23.2.
More advanced timing lost torque, dunno if it was from 91 octane gas and incipient detonation, or of the Dart Pro 1 heads are fast enough burning that any more timing isn't required.
Engine Analyzer suggested up to 36 degrees adavhnce over 4000 RPM. Maybe the exhaust restriction had something to do with it, or maybe EA itself was just making wild guestimates.
The EA Torque curve was pretty close to actual, factoring in EA gives you flywheel HP, and I was measuring HP at the ground, with a 15% or so drivetrain loss from theory.
Only bummer was I didn't have too much in the way of brakes after the dyno pulls, the 25 year old rubber hose at the rear was too old and to close to the exhaust pipe and started leaking. At least with the dual MC, I was able to limp 4 miles home with minimal brakes.
Doug
200 ft-lb of torque at idle, BTW.
Note the anomoly that starts about 2200 RPM, where power/torque suddenly drops, then takes a while to recover.
This was noticed on the 327 motor also, though on the 327 motor, it started about 400 RPM higher, there is obviously something either in the intake, or exhaust that is causing a reversion, or something, in that RPM range. I would suspect exhaust, as higher cubes = more air flow, thus a lower RPM at which it started.
The final WOT spark curve was
800 RPM 16 degrees
1200 19
2000 21
2400 22.5
2600 23.2
everything above 2600 was 23.2.
More advanced timing lost torque, dunno if it was from 91 octane gas and incipient detonation, or of the Dart Pro 1 heads are fast enough burning that any more timing isn't required.
Engine Analyzer suggested up to 36 degrees adavhnce over 4000 RPM. Maybe the exhaust restriction had something to do with it, or maybe EA itself was just making wild guestimates.
The EA Torque curve was pretty close to actual, factoring in EA gives you flywheel HP, and I was measuring HP at the ground, with a 15% or so drivetrain loss from theory.
Only bummer was I didn't have too much in the way of brakes after the dyno pulls, the 25 year old rubber hose at the rear was too old and to close to the exhaust pipe and started leaking. At least with the dual MC, I was able to limp 4 miles home with minimal brakes.
Doug
01-04-2008, 07:22 AM
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Now it's time for a mechanical engineer to explain something to me. I'm a layman, so make it simple.
Torque and HP seem to always cross at about 5200rpm. Why is that?
I don't think I've ever heard a clear explaination----------------that I could understand.
Oh ya Doug, I LIKE it. And you will too!
There's nothing like an early Vette that has a meaner bite than the big dogs--------------or at least that can put the fear into them!
And thanks for the studs.
Torque and HP seem to always cross at about 5200rpm. Why is that?
I don't think I've ever heard a clear explaination----------------that I could understand.
Oh ya Doug, I LIKE it. And you will too!
There's nothing like an early Vette that has a meaner bite than the big dogs--------------or at least that can put the fear into them!
And thanks for the studs.
Last edited by DZAUTO; 01-04-2008 at 07:26 AM.
01-04-2008, 07:55 AM
#13
Safety Car
Now it's time for a mechanical engineer to explain something to me. I'm a layman, so make it simple.
Torque and HP seem to always cross at about 5200rpm. Why is that?
I don't think I've ever heard a clear explaination----------------that I could understand.
Oh ya Doug, I LIKE it. And you will too!
There's nothing like an early Vette that has a meaner bite than the big dogs--------------or at least that can put the fear into them!
And thanks for the studs.
Torque and HP seem to always cross at about 5200rpm. Why is that?
I don't think I've ever heard a clear explaination----------------that I could understand.
Oh ya Doug, I LIKE it. And you will too!
There's nothing like an early Vette that has a meaner bite than the big dogs--------------or at least that can put the fear into them!
And thanks for the studs.
Formula for converting torque to horsepower:HP = torque * RPM / 5252
therefore at 5252 rpm HP equals torque
01-04-2008, 08:12 AM
#14
Le Mans Master
Doug
01-04-2008, 08:39 AM
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Is this also true for all internal combustion, reciprocating engines, ie diesel and radial (aircraft) engines that NEVER see anything close to 5000rpm?
01-04-2008, 10:33 AM
#16
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Thread Starter
Cam is a Comp roller, 1.050" base circle (smaller than normal to clear the rods), I/E lift of ..541/.537, .050" duration of 230/236, intake CL of 109, LSA 113.
Doug
Doug
01-04-2008, 03:32 PM
#18
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Doug, what you see as a dip is actually the truncated improvement spike of the gas inertia effect of the exhaust mass flowing in the headers. The gas inertia's first order pressure wave starts to improve the power output, and as the overall engine performance runs past the narrow improvement rpm spike the torque curve looks like it loses something. You are not losing anything, the spike in power is just the benefit result of the headers (spike rpm determined by the diameter and flow efficiency vs. displacement, and the spike strength determined by the isolated mass or primary tube volume & length).
As you can see the 1 5/8" primary tubes first order mass inertia benefit spike is below 2200 rpm. This is good for fuel economy if the spike benefit is at the drivetrain's cruising rpm. This cruise rpm benefit is why many Engineers spec a header (it sells the CAFE monitors to endorse the cost of headers, and the flow efficiency hp improvement sells the marketing department to lobby for the extra cost).
That engine will benefit from a larger header primary tube (like
it needs anything, 
right).
What I really need to know... is what color you will paint the car when you are done (so I can tell all my "hotrod" friends
in Phoenix and Tuscon there is "easy money" to be gained from challenging a 283 C1 in town).
As you can see the 1 5/8" primary tubes first order mass inertia benefit spike is below 2200 rpm. This is good for fuel economy if the spike benefit is at the drivetrain's cruising rpm. This cruise rpm benefit is why many Engineers spec a header (it sells the CAFE monitors to endorse the cost of headers, and the flow efficiency hp improvement sells the marketing department to lobby for the extra cost).
That engine will benefit from a larger header primary tube (like
it needs anything, right). What I really need to know... is what color you will paint the car when you are done (so I can tell all my "hotrod" friends
in Phoenix and Tuscon there is "easy money" to be gained from challenging a 283 C1 in town).
01-04-2008, 04:20 PM
#20
Racer
drive with that much low end torque.