MotorHead

Just read a Chevy mag article ( can't remember the exact name of mag ) they did a comparison on a 500 HP 350 ci motor with a dual plane RPM Air Gap and
single plane Victor Jr.
They used these two maniflolds because ( in their opinion ) they were the best representation of a dual and single manifolds.

The RPM Air Gap pulled more torque and horsepower up to 5300 where the Victor Jr. took over
but not by much, only about 9 more horses at 6000 RPM.

1976C3

I always thought the dual planes provided more on the bottom end and single planes on the top end. Which concur with the results. Use dual planes for street and single planes for strip. Hp is found lower in the rpm band for a dual plane & higher in the rpm band for a single plane

Is'nt that basicly the jist of it?


[Modified by 1976C3, 3:43 PM 10/2/2001]

ylose

well...isnt that the kicker...

the air gap is rated for 1500-6500 rpm ideally.......so now tell me..why would one buy the victor if its designed for top end and is almost beaten by a twin plane that gives you the lower end too?

teach this ignorant *rookie*......I have lots to learn. (in cars only that is)
:boxing:

thanks


[Modified by ylose, 2:44 PM 10/2/2001]

KenSny

It would really be useful if these mags ran "apple-to-apple" tests. How about a nice batch of dual plane manifolds. Say a Performer, RPM, Wieland, Holley, etc. on the same engine, no other changes except to tune carb if needed. I doubt if most of us are trying to decide on a RPM vs a Victor Jr. intake!

1976C3

You wouldnt want the single plane except for those higher rpm's which rev when racing. That is basicly what any intake manufactor will tell you if asked. The single plane is for those engines which constantly turnin 6k> range.

ylose

ahhh....the student nods....looking up and intently focusing on
each word spoken by the teacher !

:chevy

BSeery

I have and will always say that single plane intakes have NO place in a street driven car.

nunus79

I just bought Weiand’s TeamG Street Ram low-rise single plane manifold. I’m going to try it out-of-the-box and let you know my impression. I plan on getting some 1/4 mile ETs to measure the effectiveness/ineffectiveness of the manifold. 60 ft times should give an indication of how well this manifold would do on the street.

ML67

I have to respectfully disagree with this statement. I run a single plane in my admittedly extreme setup, but it is exclusively driven on the street. I also have several friends (70 Buick GSX Stage 1, 70 461 Chevelle SS and 64 502 Corvette) who run single planes on their pump gas street cars. One advantage of running a single plane *is* the loss of some low end -- a desirable attribute on a traction limited (ie street tire) setup.

In one of the better articles ever done by Car Craft, several camshafts (hydraulic, solid & roller of various duration) and intake manifolds (Torker II, Weiand hi-rise dual plane, Holley Strip Dominator single plane and Dart single plane) were dyno tested on a 10:1 CR oval port 461" BBC. They were surprised to find the 2 single plane made virtually the same low end as the Weiand, yet above 3500 rpm began to show sizable gain -- particularly in the Dart's case.

Have you ever driven a properly tuned big block w/ a single plane intake? On what grounds do you make your bold statement?

Please understand I am not flaming you, but I take exception to such a bold statement.

Respectfully,

Mark

oger

I agree with the need to kill some low speed torque on a BB car. The people at the Chevelle site and I have a war about it. Nice to have someone on my side. One thing you need to remember is that Mags are selling products not telling the absolute truth. A 461 with oval port heads is going to have more intake port volume problems than manifold changes can help if it is not used as a torque only engine.

BeaterShark

I agree with ML67.

Also, it would be interesting to see how much torque increase there is below 5300.

I've seen a similar comparison in Chevy High Performance. The tradeoff was basically 10 lb/ft of torque down low (which is < 5 hp at 2600 RPM) and 10 HP up high. I have a 383 which I'm still tuning with a single plane manifold which will probably have more than enough low end torque to smoke the tires, so I'm really not giving up anything to get the extra HP up high.

Just my opinion.

MotorHead

The same article says they did the same test on a 383 stroker and the it lost 65 ft/lbs of torque
with the single plane intake. It kind of gave me the impression that the bigger the block
the more you lose. They did however say that it had so much torque it didn't really matter.


I guess the reason why I posted this article was because I was kind of surprised at the the performance
of the RPM AIR GAP maniflold. It has a lot to do with a slot cut into the divider between the low
and high part of planes kind of allowing it to share the air/fuel mixture.

I was considering a single plane intake and now I'm really happy I chose the dual plane as I
don't spend to much time at 5500 RPM nor would I miss a couple of horses when I was there.
Please take note that this test was done with this particular manifold( RPM Air GAp ) others may
not fair so well against a single plane..

Don't shoot the messenger :D

BeaterShark

MotorHead,

If you remember which magazine you read that from, let me know. I'd like to see it. 65 ft/lbs of torque is far above any loss I've ever seen reported for a dual plane over a single plane.

MotorHead

I will post the magazine and page number tomorrow.

Hel I might even buy it and scan it. :eek:

marky mark

Motorhead, that's a nice looking paint job!!!

Regards, mark :flag :chevy

Stingy74

10 horsepower (or 9 really) may not seem like much but that's roughly a car length in the quarter. It could mean win or lose. I just recently got my engine back from the shop which now happens to have a big solid cam and Brodix Track 1 heads. I told the builder I wanted to use my current Offenhauser 360 and he told me to toss it. He highly suggests a Strip Dominator or a Victor Jr., the top single planes out there unless of course you count those high dollar Brodix deals. As stated in some earlier posts above the loss in torque may come in handy, espically on the street.

Jesus, the temperature in my sig just flashed -1. Winter is on it's way. :(


[Modified by Stingy74, 12:53 AM 10/3/2001]

MoMo

ML67 has a good point. But I can see both sides.

On a small block, which traditionally is (strokers not-withstanding) torque challenged, a dual plane makes a larger difference on a street car. In fact, on mild big blocks that don't ever see many rpm's past 5000, a dual plane is a good choice for a street engine.
Point well taken.

But, as ML67 points out, when you build a very strong big block, and you're making 530 lb-ft on a single plane, and still losing traction hopelessly on big fat DOT tires for two blocks +, what good is an extra 30 lb-ft going to be???
The single plane works fine on a street driven built big block, just by the extremely torquey nature of the beast anyway. You can drive it every day to the grocery store or work like that happily. But it's those times when you really want to wrap the engine tight when you appreciate having the single plane. Because they really come into their own and begin to separate themselves from the dual planes. At 7000 rpm, a single plane is going to continue breathing, whereas even the best dual planes will be on their decline.

I have an Edelbrock Torker II on a Pontiac 465 in a 68 Firebird. I have big fat rear meats in the back and they are still inadequate. What would I do with an extra 30 lb-ft down low? Spin out even further? I already have 522 at an earth-moving 3500 rpm. Granted, slicks could use the extra torque. But then what about when I'm screaming through the traps trying to get every last mph?

Actually, in defense of the RPM Air Gap dual plane, I think it is a great manifold. Maybe one of the best. Keep in mind that most dual planes are all done by a bit over 5000 rpm. Either way, you can't lose by using one of those manifolds. It's a dual plane that pushes into the single plane's traditional territory. But it's just not quite as good at the top end.

MotorHead

Now here's the million dollar question. If you put this 350 ci 500HP motor in two identical
cars with slicks so they would hook up like they're supposed to, which manifold would win in the quarter
mile.

The Victor Jr. gives you a little more HP at top revs but the RPM Air Gap qould give you
more torque and horsepower all the way through until 5300 RPM. With this in mind I would
have to think that the Air Gap would win.

This is quite interesting to me because until now I had always thought that a single plane
would win hands down in the quarter.

Also if this is true ( and I'm not saying it is ) then I see no reason at all for a single
plane on a small block for street or racing.

BTW: This motor had hydraulic cam and maxed out at 6000 RPM.


[Modified by MotorHead, 7:45 AM 10/3/2001]

JHL81

One thing I noticed that has not been picked up on is that the RPM Airgap is not a proper dual plane. The centre divider is cut down which probably accounts for it`s high rpm ability. The standard RPM intake has a full divider.

With regards to an open plane intake I ran a Torker 2 on the previous set-up and had no problems at all, the car would happily run around in 4th right down to very low revs and still pull under full throttle without the slightest hint of a stumble. I suspect that a lot of low speed running and idle problems you read about are more likely cam or carb related rather an than intake problem.

J.

Ganey

Mark & MoMo are right. Mark expect you are right again, probably no highpower BB, SB OR single plane.