SBC intake question for the experts

[novadude]

The intake that GM chose to use on this engine seems very odd to me, given the rest of the package and the intended use (street rod / muscle car vehicles, not race cars).

https://www.chevrolet.com/performance/c ... 6-turn-key

To me this engine screams "dual plane". Any idea why they chose a single plane? I'm guessing it was so they could push the peak above 400hp and publish bigger numbers for the guys obsessed with dyno figures. Seems to me that it would drive better with a dual plane, since most of these will likely end up in cars with tight converters and "street" gears.

Am I missing something, or did they sacrifice the overall curve for a "over 400hp" peak number?

[Carnut1]

For looks, gained a few ponies up top but lost a bunch of torque with that short cam. Port the heads and add a decent cam and it would be a nice little mill.

[BigBro74]

I agree- looks like they wanted to have a “balanced “ engine with 400hp and 400tq and that is probably how they got it(maybe)

[statsystems]

I don't know how you guys do it, but why is it I've been ditching dual plane intakes for decades and not lost power or made the car undrivable. Never had a complaint about no bottom end or none of that.

Surely, Chevrolet could be so stupid as to do what you suggest.

[427dart]

Well somebody get one and test it with a RPM Air Gap and see the difference! My bet the AG intake would show more torque 2000-4000 RPM!
Now how much time do you spend in that range on the street....a lot!

[Frankshaft]

Well somebody get one and test it with a RPM Air Gap and see the difference! My bet the AG intake would show more torque 2000-4000 RPM!
Now how much time do you spend in that range on the street....a lot!

But at part throttle.

[statsystems]

Well somebody get one and test it with a RPM Air Gap and see the difference! My bet the AG intake would show more torque 2000-4000 RPM!
Now how much time do you spend in that range on the street....a lot!

I doubt it. I can type out a long story of a dumb customer who thought like you do. Luckily, he didn't put much stock in interweb gurus and let me tune his car.

His exact words were "why in the f*€k would anyone run a dual plane intake?"

I said it sounds good when you bench race.

[427dart]

I have run dual planes and single planes on different engines. Have a good luck with both types depending on use.
On my 5.0 carbed H.O. engine of 1985 I liked the Weiand Xcellerator small single plane intake with the factory 585 Holley.
Ran very good with the old Ford B 302 cam and 5 spd/4.10 gear ratio....12.60's at 108.

My current 427 Windsor used the Eddy Super Vic with custom 950 Holley and was strong. However switched to semi dual plane dual Holley intake
and found it offers superior fuel distribution and a much leaner cruise A/F than the single plane. Throttle response and mid range power is excellent but it does give up some top end power to the race type Super Victor.

A good dual plane intake is by no means junk!

[pastry_chef]

Dyno sheets?

Here is one test.
https://www.powerperformancenews.com/te ... e-or-dual/

[cjperformance]

It really depends what you want though.for eg If a single plane intake allows more power between say 4800 and 6500 on a given combo and when you wring it out thats the rpm area you are using due to converter/gear etc then why would you want the better low end tq of the dual plain? Its not like the tailshaft will suddenly spin in reverse if you floor it at 2500 with a single plain!!
On the flip side, if you are not bothered about all out top end hp and rarely even see 5000 then yeah the single plain is pointless.

[Geoff2]

Yeah right, a single plane is just what you need for a 327 powered 3800lb street car.

Numerous things need to be considered before a choice between a SP & a DP manifold is decided upon.

[Newold1]

I am guessing this was more of a marketing decision versus the best performer decision on which manifold GMHPP used to choose a manifold for this crate engine offering. The newer style high rise single plane intake manifold has a bigger "cool" look versus the older "dull" looking dual plane. Since the single plain got tot their high rpm area goal for HP and torque, the marketing boys are happy. This happens with a lot of product in todays performance market. It's up to smarter, better informed users to find the best range of performance.

[Carnut1]

I don't know how you guys do it, but why is it I've been ditching dual plane intakes for decades and not lost power or made the car undrivable. Never had a complaint about no bottom end or none of that.

Surely, Chevrolet could be so stupid as to do what you suggest.

Stats, as with everything it is in the combo. Weight, gear, converter, tire size, compression, cam. I think the cross over rpm is 3500-4000 rpm, if you start making real power over this single plane all the way. I have done detailed experiments on intakes, vic jr, on roller 383 in 5800 lb truck with stock converter and 3.73 gears. Pulled great over 3500 rpm, couldn't chirp the 33' tires from a stop. Same combo dual plane and instant tire smoke. A high winding 306 Ford ran better with a dual plane because it needed the torque boost in the mid range and still pulled to 6800 rpm. Still a 3000 lb ride with tko-600 and 3.73 gears. We had plans to upgrade to hotter heads and a single plane to up the rpm and lower the E.T. but never happened. Thanks, Charlie

[Warp Speed]

TowVehicleTalk...........

It just needs a dual plane and a 224 cam with .450 lift! LOL

[RevTheory]

Isn't this the "Engine Tech" board? So I guess if you want to build an engine and don't want a 4,500 rpm converter and 4.88 gears you need to go find a different forum?

Maybe a few of you should just start a new "My Way is the Only Way and you're an Idiot if you have a different preference" echo-chamber forum.