porting injector housings to 36MM - Page 2 - ZR-1 Net Registry Forums

wfot · 03-05-2021

Pete, Excellent feedback and I appreciate all of the R & D you have done ,really spectacular stuff.

this is exactly what I was hoping for, real world results.

Graham, in your vast experience, will a port that a 36mm ball will drop thru support a motor in the 650 hp range?

I have a siamised plenum and think this is the path I want to stay on. when is the point where a dropped base would be desired?

John

Corvette95 · 03-05-2021

Quote:

Originally Posted by A26B

Really?? Where are they at? I only know of 1.

They are right beside those DIS modules you found!

A26B · 03-05-2021

Quote:

Originally Posted by Corvette95

They are right beside those DIS modules you found!

I wish!!

grahambehan · 03-05-2021

Quote:

Originally Posted by Corvette95

They are right beside those DIS modules you found!

Huh, i I didn't find any DIS modules, so that must be why I didn't see any intakes. Still interesting tho since I was asked about the intake yesterday.

Graham

wfot · 03-05-2021

Hey Graham,

when would you need to have a dropped plenum?

would that hurt drivability?

John

grahambehan · 03-05-2021

Quote:

Originally Posted by wfot

Hey Graham,

when would you need to have a dropped plenum?

would that hurt drivability?

John

The reason we did a dropped floor on the plenum was to get closer to the engine displacement wrt plenum volume, thereby, in theory, minimizing cylinder robbing as the individual cylinders demand air on opening and revert air on overlap. Really trying to minimize the effect on the standing plenum pressure from the pulses from the ports.
Did it affect driveability, no.

Graham

wfot · 03-05-2021

Quote:

Originally Posted by grahambehan

The reason we did a dropped floor on the plenum was to get closer to the engine displacement wrt plenum volume, thereby, in theory, minimizing cylinder robbing as the individual cylinders demand air on opening and revert air on overlap. Really trying to minimize the effect on the standing plenum pressure from the pulses from the ports.
Did it affect driveability, no.

Graham

I have heard that the best ratio is the plenum center should equal the volume of one cylinder. Correct?

What effect did it have on power output?

John

wfot · 03-06-2021

I was just staring down the mouth of a stock plenum and think that the total volume in that plenum is larger than 1.0 liters. this means that the plenum volume is larger than one cylinder already.

what I noticed was that the front cylinders saw the first 1/4 to a 1/3 draw from a larger/deeper part of the plenum than the back part does....

could this mean that dropping the plenum has a bigger effect on balancing what each cylinder "sees" vs having a larger space to pull from???

it looks like if you drop the floor an inch, all of the cylinders would "see" a much more even area to draw from, not just bigger...

John

LGAFF · 03-06-2021

Motor Trend/Hot Rod Magazine ran a plenum volume test for an LS motor on the show Engine Masters ......episode is called "You're going to need a bigger plenum" They ran an LS Holley high rise intake and then a massive intake probably twice the volume, at the end of the day no difference.

The guy at Westech Performance Group(They do nothing but test engines) said he has never seen EFI intake spacers etc ever make a difference. I conducted a test were I removed the top of a plenum and added a larger lid increasing the plenum volume significantly and also moving the ceiling of the plenum away from the runner entry... at the end of the day it made a few hundred more RPM at peak but there was no change on power, in fact it was down some. This was on a 350 motor with cams.... I am guessing you need a pretty big cube motor to see any difference.

Maybe Graham knows the outcome of this Lingenfelter test.. https://www.youtube.com/watch?v=UjrdqHU4JCA

wfot · 03-06-2021

OMG you did frankenplenum correct?

I saw that and did have hopes for a performance gain....

I hear what you are saying, and it does make sense, however, I am pretty sure that the dropped plenum does actually make an improvement in track times and HP numbers.. please advise if this is not true..... or true...

Does anyone have a before and after story of a dropped plenum?
John

03-05-2021	#11
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: porting injector housings to 36MM Pete, Excellent feedback and I appreciate all of the R & D you have done ,really spectacular stuff. this is exactly what I was hoping for, real world results. Graham, in your vast experience, will a port that a 36mm ball will drop thru support a motor in the 650 hp range? I have a siamised plenum and think this is the path I want to stay on. when is the point where a dropped base would be desired? John

03-05-2021	#15
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: porting injector housings to 36MM Hey Graham, when would you need to have a dropped plenum? would that hurt drivability? John

03-06-2021	#18
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: porting injector housings to 36MM I was just staring down the mouth of a stock plenum and think that the total volume in that plenum is larger than 1.0 liters. this means that the plenum volume is larger than one cylinder already. what I noticed was that the front cylinders saw the first 1/4 to a 1/3 draw from a larger/deeper part of the plenum than the back part does.... could this mean that dropping the plenum has a bigger effect on balancing what each cylinder "sees" vs having a larger space to pull from??? it looks like if you drop the floor an inch, all of the cylinders would "see" a much more even area to draw from, not just bigger... John

03-06-2021	#19
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Re: porting injector housings to 36MM Motor Trend/Hot Rod Magazine ran a plenum volume test for an LS motor on the show Engine Masters ......episode is called "You're going to need a bigger plenum" They ran an LS Holley high rise intake and then a massive intake probably twice the volume, at the end of the day no difference. The guy at Westech Performance Group(They do nothing but test engines) said he has never seen EFI intake spacers etc ever make a difference. I conducted a test were I removed the top of a plenum and added a larger lid increasing the plenum volume significantly and also moving the ceiling of the plenum away from the runner entry... at the end of the day it made a few hundred more RPM at peak but there was no change on power, in fact it was down some. This was on a 350 motor with cams.... I am guessing you need a pretty big cube motor to see any difference. Maybe Graham knows the outcome of this Lingenfelter test.. https://www.youtube.com/watch?v=UjrdqHU4JCA __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

03-06-2021	#20
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: porting injector housings to 36MM OMG you did frankenplenum correct? I saw that and did have hopes for a performance gain.... I hear what you are saying, and it does make sense, however, I am pretty sure that the dropped plenum does actually make an improvement in track times and HP numbers.. please advise if this is not true..... or true... Does anyone have a before and after story of a dropped plenum? John