seems big

 

This is a pipemax output for a 500 cuin 1400hp pro stock engine.

Minimum Plenum Volume CC = 1805.5 [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 110.2 [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 8188.0 [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 499.7 [typically for Tunnel Ram Intakes]


This one is for a 362 cuin SBC Super Stock.

Minimum Plenum Volume CC = 998.5 [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 60.9 [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 5942.9 [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 362.7 [typically for Tunnel Ram Intakes]

 

I have seen 1-1.5 x Cubic".
But thats for all out NA motor.
Im sure its different for a power adder.

 

Further, If a certain ratio of CID VS Plenum volume is a real phenomena,, why is it that a TR manifold and a single 4bbl manifold is different? and what about a single 4 TR?

 

I hope to be testing this topic this year. I had a bunch of Delrin spacers made for my sheetmetal tunnel ram intake. General consensus is that if the carbs/throttle body are on the small side (mine are) additional plenum volume will make the most difference. I also have another set of larger carbs built to try after the spacers with the current carbs.

Of course, if this year is like last year and my first day off is the week of Thanksgiving then nothing is going to happen.

Jason G.

 

Just went through this with ls 389 inch deal.We tried 380 inch on low ram.Went 5.52.Went to 430 inch plenum.5.52 et.
Went 480 inch plenum and went 5.49.The air was a hair better on last pass.Nothing in plenum area we tried made any noticable diff.All tried with same 1200 cfm carb and 9000 rpm shifts

 

I've mentioned this in posts before, but we went from a ported Edelbrock Victor Ram 2 to cutting the runners down 3.5" an adding 2.5" to the plenum and gained considerable power everywhere. - In stock form (though ported) we had significant reversion, to the point of watching smoke swirl UP out of the carb venturis (1150 dom's) at ~6k during a pull on a dyno. Tried spacers, anit-reversion plates, etc, didn't really help. The shortened runners and increased plenum helped a lot.

 

JP, how did your before and after runner lengths compare to this chart from Swarts racing?

Swartz Racing Manifolds

Swartz Racing Manifolds

www.swartzracingmanifolds.com

Did you use Pipemax by any chance?

 

I did it more via WAG....lol. Just estimated based off of what we've seen work well on some other combos and functional fitment to what I was working off of.

It made peak power at 7200 on the dyno NA, turned 8-8200 in the car with both systems on. I could shift anywhere from ~7300 - 8K and not slow down.

 

This is the pipemax output for the 500 cuin pro stock engine, 9450 rpm.



- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 26.869 (usually this Length is never used)
2nd Harmonic= 15.250 (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 10.646 (ProStock or Comp SheetMetal Intake)
4th Harmonic= 8.380 (Single-plane Intakes , less Torque)
5th Harmonic= 6.799 (Torque is reduced, even though Tuned Length)
6th Harmonic= 5.720 (Torque is reduced, even though Tuned Length)
7th Harmonic= 4.937 (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 4.342 (Torque is greatly reduced, even though Tuned Length)
Note> 2nd and 3rd Harmonics typically create the most Peak Torque
4th Harmonic is used to package Induction System underneath Hood

 

With pipemax and other programs you might be able to make "closer" WAG's when building the engine so it does not have to be done after the fact.

Pipemax on sale for 99$

Another YB member just bought it and says he thinks it's a hell of deal for 99$. http://www.maxracesoftwares.com/forum/viewforum.php?f=54 https://www.maxracesoftwares.com/ You can check out what Pipemax can show you below. http://www.maxracesoftwares.com/forum/viewtopic.php?f=14&t=263

www.yellowbullet.com

 

Looks like the chart and PM are pretty close. I cant open my old 3.98 to compare.

 

Just a general statement…….. seen plenum volume equal to 75% of total engine ci work well in all out drag race applications.

 

i know i could add plenum spacer to a 500 1/2 at a time, and it almost always showed power on the dyno.
in the car was another thing. Stack too much spacer and it wont pull a sick whore off a pisspot when you let t he clutch out.

 

My 4 cylinder drag engine want x4 of engine cid.

 

Carb size, placement and manifold design will play into what works and what don't, so your results my vary.

 

Well shit...I must have it all wrong MCSA is 3.85, runner from valve to plenum is 7-3/4 and the plenum volume is a couple inches less then 200 CI with 2 7320's on a 380 inch engine.

I have tried big plenums on other combo's before and the pigs couldn't fall out of a tree unless you helped it with NOS