porting injector housings to 36MM

[grahambehan]

Originally Posted by LGAFF

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

Yes, infinite plenum volume worked. That was a 568CID viper engine tested with a hogan intake with a relatively small plenum. With the same runners and a correctly sized plenum the engine made 920 hp.

Graham

[LGAFF]

Originally Posted by wfot

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

It?s often misleading when you see dyno tests due to variances in heat soak or weather. I tested 3 air intakes on an SLK55 AMG and it looked like one produced 12 more hp than the others but in reality it was just the manifold and engine temps that made the difference. So many tests you see could just be variances in condition

[wfot]

Originally Posted by grahambehan

Yes, infinite plenum volume worked. That was a 568CID viper engine tested with a hogan intake with a relatively small plenum. With the same runners and a correctly sized plenum the engine made 920 hp.

Graham

Mr Graham

How would I correctly calculate the plenum volume needed for a 402, 650 HPish LT5?

John

[rkreigh]

moving the coils and vacuum stuff out might allow a "bigger" dropped floor plenum. As I remember some of the frankenstein floor drop gained just a modest amount (10 or 15) on a max effort engine


I'd like to see what a fairly inexpensive individual runner ITB style intake could do.


it would remove the inlet restriction , allow running a single injector with an aftermarket Megasquirt or something similar, and should work if the linkage is progressive and doesn't snap stuff open too quick.


these are a cast iron beeotch to tune as the runners have to equalize and any slop in the linkages or blade stops will make for a bad idle.


Not sure how feasible this would be, so perhaps Graham can indulge my wild fantasy of the ITB


some of his finest work is in my bifurcation manifold, and we opened up the runners on the heads to 36.5 so we'll see what the old gal will pull soon.


I also am trying some very nice summit 24 lb injectors for just a bit more headroom as the engine should push around 650 or so if all goes well.


Needs more cam timing, but that will be another day.

[wfot]

Originally Posted by rkreigh

moving the coils and vacuum stuff out might allow a "bigger" dropped floor plenum. As I remember some of the frankenstein floor drop gained just a modest amount (10 or 15) on a max effort engine


I'd like to see what a fairly inexpensive individual runner ITB style intake could do.


it would remove the inlet restriction , allow running a single injector with an aftermarket Megasquirt or something similar, and should work if the linkage is progressive and doesn't snap stuff open too quick.


these are a cast iron beeotch to tune as the runners have to equalize and any slop in the linkages or blade stops will make for a bad idle.


Not sure how feasible this would be, so perhaps Graham can indulge my wild fantasy of the ITB


some of his finest work is in my bifurcation manifold, and we opened up the runners on the heads to 36.5 so we'll see what the old gal will pull soon.


I also am trying some very nice summit 24 lb injectors for just a bit more headroom as the engine should push around 650 or so if all goes well.


Needs more cam timing, but that will be another day.

I thought you sold the 390 LPE??

So the 36.5mm porting? is that on the housings only? does that mean a 36.5mm ball will drop thru?

the plenum? mono runners or biforcated?

[rkreigh]

Originally Posted by wfot

I thought you sold the 390 LPE??

So the 36.5mm porting? is that on the housings only? does that mean a 36.5mm ball will drop thru?

the plenum? mono runners or biforcated?

no didn't sell it. we used the checker balls on each port in the head and were able to get 36.5


port matched the intake, I don't think demps revised the intake manifold porting, but we did do the "pho mono runner mod" with epoxy to get the mono runner look which I like


I hope to get it finished up and back on the road this month.


Meantime, I bought a procharged c5 to play with. Need something nice for spring!!

[wfot]

ok, Ron, I thought I read somewhere that the 390 was sold and went oversea to make room for the C5, my bad. sucks it has been down for so long.

It is amazing how long it takes to get these things lined out the way you want. I am almost there with collecting parts. Got the cams over the weekend and they look bada$$. I need to start test fitting everything together and makes sure everything plays nice. I think I will need to have the pistons fly cut and I need to finish the housing/plenum porting... then she can start to go together..

the 36.5 must be a scary thing to do, the 36mm takes 50mm brass balls to hog out a port that big without breaking something...lol

[tpepmeie]

I realize I am in the vast minority, but I want to give my opinion on the subject. It is incorrect for one to try to correlate a certain port diameter to a "supported" horsepower for these engines. It's a fallacy that the port diameter is the limiting factor for ultimate power output. There is no equation to be had there.

Lot of people go very big. Big doesn't equal power, necessarily. Ultimate airflow is important, but not the only, constraint on horsepower output. 99% of folks limit the engines potential by camshaft choices, before the size of the ports ever become a constraint.

Couple of examples. GM Indycar engine, 3.5-4.0L, upwards of 750 bhp in those days (1997-2000). I have a few parts and pieces from said engine. The inlet ports were well under 35mm each (Yet the heads flowed over 100 CFM per sq. in. of valve area--generally 39mm valves).

427 cu. in. LT5. "Well" north of 700 crank hp. inlet ports in the head averaged 35.2mm primary / 35.8mm secondary. 390 cfm. Port was already bigger in some areas or would have been even smaller. Injector housings averaged ~38mm because the top 1" was siamesed. The critical areas were quite a bit smaller. Total average diameter of the head+housing inlet tract was 37mm. Shape and airspeed matter more than total diameter. Some areas are not perfectly round in this inlet tract. So the old drop a ball bearing test would never work in this case.

Todd

[wfot]

Originally Posted by tpepmeie

I realize I am in the vast minority, but I want to give my opinion on the subject. It is incorrect for one to try to correlate a certain port diameter to a "supported" horsepower for these engines. It's a fallacy that the port diameter is the limiting factor for ultimate power output. There is no equation to be had there.

Lot of people go very big. Big doesn't equal power, necessarily. Ultimate airflow is important, but not the only, constraint on horsepower output. 99% of folks limit the engines potential by camshaft choices, before the size of the ports ever become a constraint.

Couple of examples. GM Indycar engine, 3.5-4.0L, upwards of 750 bhp in those days (1997-2000). I have a few parts and pieces from said engine. The inlet ports were well under 35mm each (Yet the heads flowed over 100 CFM per sq. in. of valve area--generally 39mm valves).

427 cu. in. LT5. "Well" north of 700 crank hp. inlet ports in the head averaged 35.2mm primary / 35.8mm secondary. 390 cfm. Port was already bigger in some areas or would have been even smaller. Injector housings averaged ~38mm because the top 1" was siamesed. The critical areas were quite a bit smaller. Total average diameter of the head+housing inlet tract was 37mm. Shape and airspeed matter more than total diameter. Some areas are not perfectly round in this inlet tract. So the old drop a ball bearing test would never work in this case.

Todd

well I think it has become a standard for a reason, it does seem to work. a 35mm hole will flow enough air for x HP and a 36mm hole will flow y amount of HP. there does seem to be a correlation to what size people port a housing to to how much HP they can get out of it.

If you do not measure your housings by a specific size in a specific area< how do you determine where and how much to port? Is it all do this and flow test and do that and then flow test?

John

[tpepmeie]

Originally Posted by wfot

well I think it has become a standard for a reason, it does seem to work. a 35mm hole will flow enough air for x HP and a 36mm hole will flow y amount of HP. there does seem to be a correlation to what size people port a housing to to how much HP they can get out of it.
John

Ok, that's your theory, not my experience.
Good luck.