[leejoy]

guys

what is the problem with using a single plane intake manifold for a high perf street car? most guys are running dual plane. I've got a neighbor with a 71 Dart 440 that runs low 11's and he is using a single plane and his car runs fine on the street? I went for a ride with him. I keep hearing about "you need vacuum" for street cars. Well, my car does not have power brakes, and has a manually shifted automatic trans. Why do I need vacuum?

I'm about to dump $250 into a new dual plane Edelbrock Performer RPM manifold because my current dual plane manifold is limited to 5500 rpm, when it occured to me maybe I should be getting a single plane instead.

this whole frickin mess started because my engine loses power above 5500 rpm.

Lee

[RCastle]

I have used both types of intakes on the street.Ran a Performer RPM and switched to a Torker II,then switched up to a Weind Xcelerator(GOOD INTAKE!!)
You can operate just fine with either type on the street,they just perform optimally in a certain RPM range.
My first though though is what the heck are you running on the streets where you are turning OVER 5500 RPMS???
The only time I see that range is when I am launching,I do not even turn those RPM's at 55(cough,cough) on the interstate.

[Grusome Goat]

A dual plane is a better choice especially with a street car amd some street/strip cars. Depending on your engine combination there is more that limits power in an RPM range than the intake. Camshaft selection is the most important factor in limiting RPM. Your neighbors 440 was likely built to run in a higher RPM range to where the single plane is more effective and decided on a camshaft profile to where his vacuum will be lower than on a street engine. A good example of an intake comparision has been on my GTO. I used to run an Edelbrock Performer when I first put my 400 together several years ago. At the track the car ran a best of 8.72 in the eighth. A cam change to change the power range higher up in the RPM's and an intake change (intake an Edelbrock Torker) car ran a best of 8.52 with sixty foot times in the low 1.90's. Changed back the orginal cam along with the Torker and times dropped and sity foot times stayed the same, changed to a stock Pontiac iron intake and car ran a best of 8.46 (with a broken motor mount and trans mount that had happened on the first pass of the evening) with sixty foot times of 1.80-1.86. If it had not been for break parts that night I could have ran quicker but being a 4 speed car it made it very difficult to shift. But my point is that the wrong intake can take away from an engines full potential, same as the wrong cam or timing. A street engine doesn't normally see the high side of 5500 unless someone is street racing or trying to turn a big block clear higher than what they need to. My .25

[red65mustang]

lee,

you can "make" a open plenum work on the street.....just costs more $$$$ for less street performance

betcha your buddy has a msd 6al or other ign box on his motor with the single plane manifold.....(and probably 4.11+ gears to get his street rpms higher for more vacuum)

the "vacuum" reading (Hg) gives you a "indication" of the "velocity" and the "quality" of the air/gas mix going into the cylinder....
a carb needs 14Hg or more to keep the air/gas in suspension driving normal... at low street rpms below 14Hg the gas will puddle and foul plugs (worse with cold weather)....open plenums typically are 8-11Hg (depends on the cam)

so... for street rpms with a open plenum...
you add a "multispark" box for a "better chance" of getting the crummy mix to light and burn and set the idle to about 1000+ to get enough Hg to idle....and really deep gears for more rpms in town which sucks for mpg and rpms on the hwy....

you need none of the above with a dual plane intake (with a reasonable size cam) and will make alot more TQ and HP at the street rpms where you actually do drive the car

ps: power brakes and Hg
there is a check valve in/at the booster, "blip" the throttle just one time so Hg goes to 18Hg+...the booster stores the vacuum to operate the brakes......a good check valve will hold the vac for 24 hours plus with the engine turned off

[ChevelleSS_LS6]

Originally Posted by leejoy

this whole frickin mess started because my engine loses power above 5500 rpm.

Lee

a) are you driving a Honda s2000? 240 hp @ 8,300 rpm and 153 ft·lb of torque @ 7,500 rpm. To get anything you'll NEED to rev over 5500 in this thing.
b) do you like valve float?

Unless it's more of a race car than a street car, you don't need to worry about power over 5500. On the street most people seem to want a lot of power right here, right now. Which is torque, not horsepower. Dual plane intakes are better for torque. Keep the dual plane and the revs not quite so high.

[timemachine]

im no expert, but i had a 402 big block chevy with a team g single plane that pulled to 6500 without a problem, the combo was budget-matched. meaning that i got the closest cam i could from a swap meet or ebay! the cam was rated at 3500-7000, a little hairy, but still powerful. i now have a 468 with a slightly smaller cam (3200-6200) and a dual plane weiand stealth, it pulls like crazy all the way to about 5600-5800, but seems to be more street-able. i think my 750 cfm carb is the limiting factor here though, its on the small side for my cid. through research and reading, i have discovered that the weiand stealth dual plane and weiand team g single plane are some of the better intakes out there. i have experience with both, but no basis for comparison to others. for a weekend-bracket-cruiser-bruiser, i would easily go with a single plane, for more of a cruiser or daily car, a dual plane. thats my 2 corn flakes (out of sense, i mean cents ).

[F-BIRD'88]

Originally Posted by leejoy

guys

what is the problem with using a single plane intake manifold for a high perf street car? most guys are running dual plane. I've got a neighbor with a 71 Dart 440 that runs low 11's and he is using a single plane and his car runs fine on the street? I went for a ride with him. I keep hearing about "you need vacuum" for street cars. Well, my car does not have power brakes, and has a manually shifted automatic trans. Why do I need vacuum?

I'm about to dump $250 into a new dual plane Edelbrock Performer RPM manifold because my current dual plane manifold is limited to 5500 rpm, when it occured to me maybe I should be getting a single plane instead.

this whole frickin mess started because my engine loses power above 5500 rpm.

Lee

"runs fine on the street" is a relative term. yes a single plane will run fine on the street. In a street environment, a dual plane will run finer.
A RPM hi rise dual plane has a much stronger top end than the performer.
its strong well past 6000rpm, yet makes more power in the low and mid range than a single plane does. A single plane manifold wants a lot of rpm . works best from 4000rpm up. Wants a stiff gear 4.10+ and a very high stall ( 4000+rpm stall best) A dual plane rpm manifold has a much broader rpm range and cruises a lot nicer overall. Especialy at low rpm.
Your motor is a toss up as to which is better. RPM or single plane Vic JR type.
I would go with the RPM air gap combined with the other upgrades you have planed. Avoid the Edelbrock Torker II 2 O, Even if someone offers to give you one. They stink. The lowly performer is a better manifold.
A single plane manifold wants a longer duration cam also 250+@.050" and lots of rpm. Best with a solid lifter cam that can rev.

[67tiger]

ok so id like to know, can you modify a dual plane so you can get a more rpm, while still getting good low end?

[F-BIRD'88]

Depends on what manifold. Add a carb spacer to increase the plenum volume. Use a larger carb. Just replace your manifold with a rpm type with airgap.

[stepside454]

I wouldnt worry so much about it being an "air-gap" style, but a large plenum, large runner dual plane, such as Performer RPM ( air-gap or not) Dart, Weiand Stealth work great. I depends on the engine, some motors Ive seen run great on the street with a single plane, but most respond best with a dual plane. not all dual plane, or single plane intakes are created equal

[65 Imp SS]

leejoy, how much cam and compression are you running?

[leejoy]

Originally Posted by 65 Imp SS

leejoy, how much cam and compression are you running?

well, compression is "estimated" at about 10:1. Never did a Comb Chamber volume check.

How much cam? well.....................I'm in the process of considering changing the cam. see the hundreds of other threads I have going right now. Crazy...........

[65 Imp SS]

lee, you have pm.

[454C10]

I have a 2800 pound car with 3.90 gears and a t5 speed powered by a 11:1 sbc with a 244/244 cam and a 200cc dart iron eagle heads. Pulls hard to 7000 rpms. I ran both the rpm intake and single plane team G. I liked the rpm intake better. Car runs mid 11's at 120 on the motor and mid 10's at 135 with a 175 shot of n20 with the rpm intake.

I also ran an rpm air gap on a street engine and didn't like it. No heat riser in the intake made the engine have stumble problems for 15 minutes if the temps were under 60 F. If you live in a cool climate and plan to drive the car in the winter then get a regular rpm intake.