Engine performance data

[David Redszus]

Engine Pro the book has done something like what you have in mind.

A quick review of the book index does not indicate that the subject has been addressed.
Nonetheless, I have purchased the book; it never hurts to try to learn something new. Even if it only confirms what you already knew.

[norm]

598 ford

4.5" stroke
883 HP at 6600
821 tq at 4600

[David Redszus]

598 ford

4.5" stroke
883 HP at 6600
821 tq at 4600

BMEP 14.3bar
Sp 17.5 m/s

[John Wallace]

What are you trying to correlate this data to?

Average piston speed of engines now-a-days?
Torque to piston speed?
HP to piston speed?

P. Hale's book uses a '7' step process for engine performance parameters.
Not 1 thing is important.
All parameters needs to be compatible to each other.

[David Redszus]

What are you trying to correlate this data to?

Average piston speed of engines now-a-days?
Torque to piston speed?
HP to piston speed?

P. Hale's book uses a '7' step process for engine performance parameters.
Not 1 thing is important.
All parameters needs to be compatible to each other.

John
I am not trying to correlate this data to anything, but rather determine if there is a pattern to optimum mean piston speed related to best performance.

Mean piston speed is a much better indicator of breathing limits than is rpm.

BMEP is a measure of torque but is nomalized for engine displacement.

Horsepower is not related to engine breathing, except in a most crude manner. Best breathing and combustion occurs very near peak BMEP.

While several engine parameters are important to engine performance, they are not all of equal value.
I would rank induction pumping performance on a level with combustion phenomena in order of importance. Everything else is down on the list.

[NewbVetteGuy]

Ancient thread, I know.

Did you come to any conclusions or rules-of-thumb on this, David?


Here's a weird data point that I'm curious about whether it "breaks things":
SBC 383
534 ft lbs @ 4,200 RPM, 458 hp

BMEP = 14.3 bar
Piston speed only 13.3m/sec

(Long-runner TPI build so high BMEP @ torque peak for the piston speed.)
http://www.superchevy.com/how-to/engine ... induction/



Adam

[smeg]

277 cube
505 hp @7900
375 ft lbs @6200
3.796 bore
3.062 stroke

[af2]

2500 lbs 9.51 at i39mph ?

[rustbucket79]

406 Sbc
4.155 x 3.75
545 T 5600
670 HP 7500

[David Redszus]

Attached is a plot of BMEP (BAR) vs Mean Piston Speed (m/s).

Based on the furnished data samples, few engines produce maximum BMEP at high piston speeds.

BMEP vs MSp.pdf

[Rick!]

598cid BBM
4.600 bore
4.50 stroke
880tq@5600
1070hp@7000
15.3 BMEP
26.7 m/s at peak power
21.3 m/s at peak torque

[David Redszus]

The same type of graph could be produced using BMEP at peak power instead of at peak torque.
That would indicated the ability of an engine to breathe at higher piston speeds.

The point is to evaluate the state of tune of a performance engine regardless of displacement.

Alternate graphs would be needed for four valve and turbo engines.