Modern Single Plane Intake Flow Questions

[Cyclone03]

Of the 2 common single plane intakes Edelbrock Victor and Trick Flows Trackheat(?) for the FE ,does one have better as cast flow balance than the other?

Does one have flow better than the other?

I'm running FAST ez2.0 TB injection on a Performer RPM with a 1” open spacer and the mixture distribution is noticeably uneven. Numbers 1&5 are leaner than 4&8 so high/low plenum doesn't appear to make a difference. The spacer helped this but it's still noticeable .

The engine is a 433” (4.70 x 4.125) with a set of Berry's Stage X Edelbrocks  from about 10 years ago, they got freshened last year, 270@.600 . Hyd roller from Brent. I have no lack of low end with a 3.70 rear gear and TKO 5spd.

So oddly,to this group I'm sure, I'm not looking for max peak flow I'm looking for balanced flow,much in the same way balancing the flow on the old 5.0 intakes increased performance. I'm sure JDC had his hand in a few of those back in the day. It was a very popular mod here in San Antonio.

So I guess I'm asking which of those two have the smaller runner cross section.

[1968galaxie]

Fuel distribution issues with an intake manifold may have nothing to do with the manifold flowbench numbers on individual ports.

[Joe-JDC]

What?  That statement needs some explaining.  I totally disagree!  Joe-JDC

[Cyclone03]

Joe, I worked for Rusty Mahan and had the opportunity to drive his 88 LX, I believe you ported the intake on it,picked up the flow on #5 (or #1?) something like 60%.

So knowing from my own testing that my TB injection works much better with an open spacer on a Performer RPM my thought was remove the plenum,but of course Jays excellent book has data that warns against that,but that’s with a carb. Soooooo cut out the plenum? Or switch to a single plane? I feel the better balanced intake would perform better with TBI,that is the recommendation on every SBC test with TBI.

So I’m back to my original question ,which of the modern FE single planes has the better port/port balance?

Thank all.

Lance Howlett

[1968galaxie]

What?  That statement needs some explaining.  I totally disagree!  Joe-JDC

Are you saying that an intake manifold that shows the same flow(balanced) on all ports will have no fuel distribution issues?
If so I have swamp front property to sell you.   (Joke)

[Joe-JDC]

The RPM intake is not a balanced intake for flow.  There is a difference of several cfm between the lower plane and the upper, but that does not keep the engine from using what is available to it.  The TFS, Victor 427, Holley Street Dominator, Edelbrock Streetmaster are all good manifolds with a little work.  Hood clearance would be the deciding issue as to which intake you choose, but a spacer will work on the RPM if you can round over the plenum divider and remove some of the turbulence caused by the sharp edges.  On the RPM, ports #5 and #8 will be the lowest flowing, and need the most work to balance the flow.  Joe-JDC

[Joe-JDC]

Fuel distribution issues arise when the fuel hits the plenum floor and is not directed in a clear path to a port.  Just this week, I had the privilege of working two days on a dyno where we used single plane intakes, and dual plane intakes in comparison testing.  The dual plane with ridges in the floor of the plenum did well in keeping the fuel in suspension, but the one with dimples did better, and had a better torque average as well as horsepower average.  The single planes were the same manifold, but one was stock, and one I ported.  The stock single plane had a plain floor, and at the top of the dyno pull, fuel was seen actually swirling and misting above the carburetor due to fuel bounce back on pulsation of the wave lengths. The ported single plane had dimples in the floor, equal flow in each runner within 4 cfm, and did not have any fuel mist or vapors swirling above the carburetor at the top of the rpm pulls.  I am talking 7400 rpm, so it was not a toy.  We made our pulls 3000 to 7400 rpm which is not normal, but stressed the engine to see how it would react.  Headers, carb spacers, plenum work, valve lash, carb jetting all come into play when trying to maximize a combination, and I definitely am a proponent of equalizing manifold runner flow in cfm.  After building engines for 57 years, I feel I can say this with confidence.  Joe-JDC

[pbf777]

     Rather than attempting to make the 180° dual-plane intake function in the fashion you desire, I would switch to a single-plane 360° plenum intake, as this execution is going to prove more capable in the beginning, and easier in the end to accomplish your goals.

     Yes the divider in the dual-plane is mostly there to aid in providing an acceptable signal  for the betterment of the carburetor's function, which this intention is greatly negated with E.F.I. so it's removal (to some degree) may aid in the similar effect of as adding the open plenum spacer above, which is defeating this effect.

     One would want to attempt to acquire equal flow numbers, port to port, as indicated by say a flow bench, but equal flow of air and fuel values to the functioning individual cylinders may still not be acquired as anticipated  due to other intervening mechanical influences.  But just understand, that having equivalent cross section in port dimension, or equal intake manifold flow numbers, although a good start, may still fail in proving "equal" sums delivered; experimentation within the entire induction system, as this effect is not only within the realm of the intake manifold, and even influences from the exhaust pluming must be considered, depending on how in depth ones' intentions.

     Me, I think I'd buy the Edelbrock Victor intake,..........if it'll fit under the hood.       

     Scott.
     

[machoneman]

"I'm running FAST ez2.0 TB injection on a Performer RPM with a 1” open spacer and the mixture distribution is noticeably uneven. Numbers 1&5 are leaner than 4&8 so high/low plenum doesn't appear to make a difference. The spacer helped this but it's still noticeable."

I'll guess your uneveness is found by spark plug inspection? Or sensors in each exhaust manifold, unlikely as this may seem?

I ask since low rpm operation can play havoc with air/fuel distribution. Today's modern engines for some time now have direct port injection or, as with older V-8 designs, 8 manifold injectors designed to defeat, at least, uneven fuel supply at all rpm levels. Air supply, before the injectors, with these engines is still a challenge mainly due to under-hood packaging issues. With the need to use what are essentially carb-designed intakes, even a 4-hole EFI throttle as you know can't fully overcome some imbalance in air/fuel supply. You've raised an interesting topic here that few have explored.

[Yellow Truck]

The stock single plane had a plain floor, and at the top of the dyno pull, fuel was seen actually swirling and misting above the carburetor due to fuel bounce back on pulsation of the wave lengths. Joe-JDC

Don't want to distract from the main thread, but I'd like to know how you could see what you are describing. I've only dyno'd one engine and it was in the truck, so I am very curious what kind of setup you had to see the flow through the intake.

[Cyclone03]

machonemane
Your last statement is the conversation I’m interested in...

Public,common,or conventional testing I’ve seen on the subject of TBI intake use has all been SBC centered.
Engine Masters just tossed the dual plane for a single and called it done. I’d hate to cut the divider away and end up worse with an intake that now requires machine work to reinstall the divider ,like Jay did for his Dyno test. Or weld in a replacement.

[Cyclone03]

The stock single plane had a plain floor, and at the top of the dyno pull, fuel was seen actually swirling and misting above the carburetor due to fuel bounce back on pulsation of the wave lengths. Joe-JDC

Don't want to distract from the main thread, but I'd like to know how you could see what you are describing. I've only dyno'd one engine and it was in the truck, so I am very curious what kind of setup you had to see the flow through the intake.

GoPro or equivalent focused strait down the carb on an engine Dyno .

[frnkeore]

Joe, I'm interested in the dimples you tested. Would you have a picture? I take it that they're round? If so, what is the diameter and depth? Is there a pattern that works best?

Also, I take it that the ridges, in the one manifold are at 90* to the flow? What about the X hatch pattern manifolds, how do they compare?

[Joe-JDC]

Like Jay said, I like all the single plane intakes for a street build, especially if you do a little work in the plenum to turn the airflow into the ports.  It is fairly straightforward, and easy with a carbide and die grinder.  Port matching is not critical, but cleaning up the runners of any slag is.  As for seeing fuel distribution issues on the dyno, I have been on hundreds of dyno sessions, chassis as well as engine dyno testing.  You can see fuel coming back up out of the carburetor at certain rpm due to several reasons, one of which is the fuel slamming into the plenum floor and bouncing back because the plenum is too short.  Fuel and air need room to turn effectively, and the deeper the plenum to a point, the better.  The PI intake is a good example of a plenum that is too short to make the best power, and why a RPM is better.  The RPM has a deeper plenum which gives the air more room to turn into the ports without fuel coming out of suspension.  If you doubt my advice, next time you have your intake off the engine, spray a water hose directly into the plenum like the carburetor would, and you will get your insight awakened in a splash.  Joe-JDC

[Cyclone03]

Joe, looking at the RPM 5&8 deeper plenum,long runners and.....do those runners have to turn up to get to the intake valve ? 


I’m thinking I need to jump on Jays Street Dom on eBay ....