Dual plane
08-07-2012, 08:14 AM
#1
Staging Lane
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Dual plane I'm building a stock stroke 3.622, with a 4.170 bore street 396 inch LSX. I'm using the LSX dual plane intake. Don't plan on anything over 6000 rpm. Does anyone have any feedback on this manifold as far as torque or mileage? Will be running a 3.55 geared 8.8 Ford rear with manual trans in a late model Mustang.
08-07-2012, 08:51 AM
#2
To get numbers check out some of the car mag articles comparing single and dual planes on LS motors. You need to be a little careful interpreting them cause some of them use stroker motors or stock truck valve trains which experience valve float anywhere near 6K. These tend to understate the benefit of the single planes.
I’m not sure if you are going there but as for opinions of single vs. dual plane, that is sort of a religious argument with most folks. Only a handful of guys who I know for certain have done back to back comparisons with the single and dual planes. Check out Speedtigger's car. He started with a dual plane but ended up with a single.
Chances are your motor in particular is going to make more midrange torque than your car will be able to use. In that case you might as well trade some of the midrange for upper RPM HP. LS motors have a good bit more torque everywhere than first gen SBC’s, so your car will remain streetable. Believe it or not carb intakes, single or dual, have more low RPM torque than EFI. So even better yet.
I can tell you from experience my stock cam LS2 runs beautifully on the street with a single plane. With a 2500# car I am in fifth gear by 35 MPH, car pulls smoothly from 1200 RPM and pulls down better than 25 mpg. I would probably do better with a 6 speed to get more overdrive.
I’m not sure if you are going there but as for opinions of single vs. dual plane, that is sort of a religious argument with most folks. Only a handful of guys who I know for certain have done back to back comparisons with the single and dual planes. Check out Speedtigger's car. He started with a dual plane but ended up with a single.
Chances are your motor in particular is going to make more midrange torque than your car will be able to use. In that case you might as well trade some of the midrange for upper RPM HP. LS motors have a good bit more torque everywhere than first gen SBC’s, so your car will remain streetable. Believe it or not carb intakes, single or dual, have more low RPM torque than EFI. So even better yet.
I can tell you from experience my stock cam LS2 runs beautifully on the street with a single plane. With a 2500# car I am in fifth gear by 35 MPH, car pulls smoothly from 1200 RPM and pulls down better than 25 mpg. I would probably do better with a 6 speed to get more overdrive.
08-07-2012, 09:07 AM
#3
Well I want to jump in on this as it seems like i need some insight...my car is 4000 lbs...and I was considering the dual plane as I dont/wont shift it past 6500 and im building it more everything under 6500 so I chose the Edelbrock RPM dual plane intake. this will be on top of a stock LQ4, longtubes, 750 carb in a 87 caprice for now, will mill the 317s or change to 243s and eps cam later...I've been reading and reading on comparison between single and dual but with a car that wont EVER see 6500+ rpm and is quite heavy, is it really needed???
NOT TO HIJACK BUT WAS JUST CURIOUS!
NOT TO HIJACK BUT WAS JUST CURIOUS!
08-07-2012, 09:15 AM
#4
Most of the experience I have and have heard about has been with the Edelbrock Performer RPM dual plane intake. The GMPP LSX dual plane manifold for square port heads is likely a bigger intake with larger runners and more volume. Although, I have never inspected or measured one in person. For your lower RPM application, I am sure the intake will work great for you. If you are running a low numerical rear axle ratio or a stock transmission torque converter, I would certainly choose the dual plane design.
08-07-2012, 09:26 AM
#5
if this response was to me then, i have a custom built 3000 9.5" converter in a TCI 700r4 that has been beefed up some more by my local trans guy...and my gears are 3.42 with powertrax locker. Was thinking of going to a 3.73 but I think the 1st gear of the trans and the 3.42 is good enough..btw, my car came stock with the 8.5 rear and 28 spline axles so i think i can put a lil power to it.
08-07-2012, 01:23 PM
#6
The cross over point is well below 6500 RPM, so yes, depending on your gearing and how you want to drive the car it can be beneficial.
08-07-2012, 10:25 PM
#7
Staging Lane
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My intake is the GM LSX rectangular port dual plane not the cathedral port Edelbrock. It has some serious size runners. I have an 850 carb for it. The car will be around 3000# and have a manual trans with 355 gears. What I see from the factory is long runner manifolds that fit under the hood. Same thing my dual plane does but with a carb. That may change too. I saw this dual plane manifold with EFI and the owner said he picked up 3 mpg. It's going to be a fun engine project. Gathering parts now.
