Torque per Cubic Inch

# Thread: Torque per Cubic Inch

1. ## Torque per Cubic Inch

Are any of you guys aware of a general (or specific) value for torque per cubic inch, that indicates 100% VE for different compression ratios?

Looking for a format that reads similar to below. (values shown are guesstimates I pulled out of my ass)

1.00 ft.lbs./ci @ 8:1cr = 100%VE
1.05 ft.lbs./ci @ 9:1cr = 100%VE
1.10 ft.lbs./ci @ 10:1cr = 100%VE
1.15 ft.lbs./ci @ 11:1cr = 100%VE
1.20 ft.lbs./ci @ 12:1cr = 100%VE

2.

3. This should be good.

4. wow! I don't have to spend any more money, I am maxed out! the math should only make 1.27 to 1.29 per cubic in. at 10.5 comp. with 565ci. comes to 717.551 lbtq. 565ci at 13.5 comes to 788 lbtq, how does that compute to the ( I think dne or dnr something built a 565 that made like 900 lbtq and 1040 hp on pump gas ) you do use the volume efficiency # which is the same # used in figuring cfm and it does not work out to good for a NHRA 355 prostock truck

5.

6. the math says a torque value of 1.27 per cubic inch at 10.5 compression and calculate a .0307 increase for every point of compression for a n/a motor. I also know a guy who says he built a motor with Chinese beads, it ran like shit, guess their isn't many hotrods in china

7. Originally Posted by eric tx20
the math says a torque value of 1.27 per cubic inch at 10.5 compression and calculate a .0307 increase for every point of compression for a n/a motor. I also know a guy who says he built a motor with Chinese beads, it ran like shit, guess their isn't many hotrods in china
Is the 1.27 you mention maximum torque divided by cubic inches, torque at 100% VE divided by cubic inches, or something completely different?

I'm specifically interested in the values at only 100% VE, not maximum achieved or achievable at VE's greater than 100%.

8. I think this is one of SleeperCP's engines.

If you take the values above and below 100% VE and average them you get 518ft.lbs @ 100.35% VE (close enough), divided by 409 cubic inches...

1.266ft.lbs/CI @ 11.9:1cr . For my purposes I'd be fine just calling it 1.27ft.lbs/CI @ 12:1. I'm having trouble locating enough dyno sheets that report VE to draw any conclusion or average. Hoping some of you guys can help out and add your results to the pool or link to some.

9. Originally Posted by Budweiser
I think this is one of SleeperCP's engines.

If you take the values above and below 100% VE and average them you get 518ft.lbs @ 100.35% VE (close enough), divided by 409 cubic inches...

1.266ft.lbs/CI @ 11.9:1cr . For my purposes I'd be fine just calling it 1.27ft.lbs/CI @ 12:1. I'm having trouble locating enough dyno sheets that report VE to draw any conclusion or average. Hoping some of you guys can help out and add your results to the pool or link to some.
What determines percentage of VE? HOw is it being measured?
100% @ what rpm? Peak tq only? 100% VE can occur through a wide range of rpm.
Typically, VE falls off with rpm (unlike the above dyno sheet) and that's why tq falls off.

10. Originally Posted by steelcomp
What determines percentage of VE? HOw is it being measured?
100% @ what rpm? Peak tq only? 100% VE can occur through a wide range of rpm.
Typically, VE falls off with rpm (unlike the above dyno sheet) and that's why tq falls off.
All good questions and points. I'm glad you chimed in.

To answer your Q's: As far as I know, airflow is measured with a "turbine" and VE is determined by comparing measured airflow to engine displacement and rpm.

What I'm trying to figure out is just a simple value for torque per cubic inch at 100% VE given different compression ratios. I could be wrong, but I don't think the rpm it occurs at will change the outcome much, if at all. Even if it occurs over a wide rpm range, the torque should be the same across the range too... Shouldn't it?

There's a lot of good conversation to be had around the subject and I suspect this thread will wander toward peak torque per cubic inch. I've read some threads you've participated in on that particular subject and my hat's off to you sir.

I'm sure you have a good handful of N/A dyno sheets to reference. What are the numbers saying? CR for CR, is the torque at 100% VE (whatever rpm it may be at) divided by CID fairly consistent? What are they for 8, 9, 10, 11, 12, etc. :1 CR's? If it is fairly universal and consistent, I can't imagine that would be proprietary or privileged info.

11. Something's off with that dyno sheet. Seems as though the VE is being calculated for a 369ish cid engine, not 409.

12. Originally Posted by Budweiser
All good questions and points. I'm glad you chimed in.

To answer your Q's: As far as I know, airflow is measured with a "turbine" and VE is determined by comparing measured airflow to engine displacement and rpm.

What I'm trying to figure out is just a simple value for torque per cubic inch at 100% VE given different compression ratios. I could be wrong, but I don't think the rpm it occurs at will change the outcome much, if at all. Even if it occurs over a wide rpm range, the torque should be the same across the range too... Shouldn't it?

There's a lot of good conversation to be had around the subject and I suspect this thread will wander toward peak torque per cubic inch. I've read some threads you've participated in on that particular subject and my hat's off to you sir.

I'm sure you have a good handful of N/A dyno sheets to reference. What are the numbers saying? CR for CR, is the torque at 100% VE (whatever rpm it may be at) divided by CID fairly consistent? What are they for 8, 9, 10, 11, 12, etc. :1 CR's? If it is fairly universal and consistent, I can't imagine that would be proprietary or privileged info.
I don't pay a lot of attention to VE numbers since it can be so widely manipulated. Should be interesting to see where this goes.

13. The afr on that sheet sure looks as if its runnin outta fuel pump or mainjet up high

14. Originally Posted by IMPATIENT 1
The afr on that sheet sure looks as if its runnin outta fuel pump or mainjet up high
Most be a printer error because we all know the highly touted O2 near tells a lie.

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15. Originally Posted by Budweiser
Something's off with that dyno sheet. Seems as though the VE is being calculated for a 369ish cid engine, not 409.
Like I said, I've never seen VE continue to increase at upper rpm levels.
How much is going out the exhaust because of overlap? How well was the air turbine calibrated, or when was the last time it was calibrated? Couple things to consider.

16. Originally Posted by gn7
Most be a printer error because we all know the highly touted O2 near tells a lie.
So therefore it's better to never know what it is.
That's how we did it in the 1970's

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