speedtigger

iTrader: (16)

That is the sneakiest build ever. Fantastic. - End high-jack. Sorry OP!

Pop N Wood

iTrader: (1)

Boy, not to start a war but I don't agree with much in this statement. A little too generic.

Carb'd single planes don't have drivability issues once tuned right. At least mine doesn't. I can drive all day and never go over 2000 RPM. When just cruising I will be in 5th gear by 35 mph, car pulls smoothly from 1200 RPM like that. Not sure what else you can ask for. I do have a relatively light car (2500#) with a relatively mild cam (stock LS2-LS6 cam).

I know you posted a link to the one car mag article that showed a pretty healthy increase in low end torque from a dual plane compared to a single plane, but that is the only article I have ever seen that showed such significant difference. All the others I have seen showed very marginal differences at low to mid RPM’s. The thing the article did miss was comparing the torque curve of the single plane LS motor to a typical first gen motor. Even with the I think 59 ft-lbs difference the single plane motor flat smokes most first gens, dual plane or not.

For people like me with a traction limited, light car there really is no upside to the dual plane. I can’t use all that low end torque anyway, so might as well trade it for the upper octaves.

But like one car article said the single vs. dual plane argument is probably as old as hot rodding itself. But I still think different rules apply with the increased everything of the LS motor. Even for heavier cars with automatics I think the potential of the single plane on an LS motor is the way to go.

speedtigger

iTrader: (16)

Pop N Wood, how big is your cam? Larger cams with higher overlap induce pulses into the intake tract. These pulses exacerbate drivability problems on carbureted engines by upsetting the idle and low speed fuel metering systems at low RPM. Dual plane manifolds lessen these pulses and aid drivability. In addition the longer runners of the dual plane improve cylinder filling at low RPM and substantially improve low rpm and midrange torque.

For the sake of full disclosure, I drove my 62 Vette around on the street for 2 years with a Weiand Team G single plane intake, 800 DP and a solid cam that was 254 degrees at .050". So, I fully get that drivability is in the eyes of the beholder. However, my 78 Camaro was much more driveable and far less fussy when cold with a dual plane and a came that was 234 degrees at .050". In all fairness, care to guess which one was faster?

All in all, if you have a camshaft that is big enough to cause some fussy behavior at lower RPMs, a dual plane design will improve drivability. And if you have a converter of 3500 RPM or less and you are shifting at 6500 or below, it will likely be quicker too.

Motovative

iTrader: (19)

We could make these pretty easily if there is enough interest.

Pop N Wood

iTrader: (1)

Like I said, stock LS2 cam (i.e. LS6 cam).

You seem to still be talking first gen SBC. Different animals IMO.

In all honesty this is the first time I've heard anyone recommend switching to a dual plane intake as the cam gets too big. Seems unbalanced.

speedtigger

iTrader: (16)

Your stock camshaft is the reason you don't have drivability problems. Your car will have good drivability with any intake.

While you might be inclined to believe that the LS engine are so uniique that the things we have learned about the overhead valve v8 over the last 50 years do not apply, there are some things that are just as relevant as ever. In fact there are 2 published ls intake dyno tests you can read about in the carbuereted forum that demonstrate what I have described perfectly. I would post a link but I am on phone browser.

rojs234

iTrader: (5)

I'm afraid I'm going to have to side with *speedtigger * (again), on this one. You may not like dual planes or think they would'nt work on your light car but it's hard to ignore facts. Since everyone else has cited various Magazine articles, I'll do the same. Back in Feb. '05, when MSD first brought out the 6010 box for LS engines, Hot ROD and Westech ran a dyno test on a brand new LS6, which is pretty much identical to your engine except for your larger displacement. They used the GM single plane and the Edelbrock dual plane. All tests used the #6 MSD timing pill. They tested with the stock cam and two Crane cams...one on 112 lsa and the same cam on 110lsa. The dual plane was, according to them a much better choice on the stock cam with power levels finally crossing over to a slight advantage to the single plane above 5700RPM but mostly by only 5-7 HP. Dual plane had big advantage at lower RPM. The Crane cams were both 228-232 @ .050. Their take on the 112 lsa cam was that you would have to try it at drag strip to see which intake would get it down the track quicker, but the 110 lsa cam was enough better at most places on the RPM scale with the single plane that they pronounced it the better choice in a drag strip situation. Pretty much what *speedtigger * was saying. At least that's the way I took it. By the way, with just headers and an electric water pump the 110lsa cam made 530HP! Still made 514HP with the dual plane. Sorry to be so long winded. LOL Ron

Pop N Wood

iTrader: (1)

Gonna have to respectfully disagree with you guys. This is a matter of interpretation. Yes, longer intake runners buy mid range torque. That is why they build EFI intakes the way they do. So do narrower intake/exhaust ports as does smaller volume port.

But you need to put numbers to things. Words like "substantially" and "dramatically" are a matter of opinion. So are blanket statements like basing the intake simply on the stall speed of the converter.

The book below does a single vs dual plane comparison also. LS1 motor, long tubes, 212/218 Voodoo cam and BG 750 mighty demon. Dual plane outperformed the single from 4500 RPM down. The peak torque difference was 38 ft-lbs for the dual plane, peak HP was up 12 hp for the single plane.

Dramatic? Significant? Matter of interpretation? Need to look at the dyno curves and see how it fits your car.

But the point that keeps getting missed is the amount of torque these motors make down low compared to the first gens. Even with the 38 ft-lb drop you are still over and above what the early motors did.

I absolutely think the things learned in the last 50 years apply. So do the laws of physics. But I also say the old thumb rules applied to the first gen motors absolutely have to be rethought for the LS motors. How many times I have read someone saying a 750 carb is too big for an LS1?

I think of LS motors more like a first gen with Brodix 15° heads. Would you really buy a set of those then reuse your tuned port injection intake because you get more torque down low? No, because if you just want a cruiser you won’t put sprint car heads on it in the first place. Same decision when looking at port volumes. Don’t buy a head with 225 cc intakes when 195 cc heads better fit your cam and intended use.

And what are LS1 heads? 15° valve angles that flow like an AFR 225 head wished it could flow.

I guess what I am saying is just how much torque down low do you think you need and don’t overlook the high RPM potential of these motors. LS motor like to rev, take advantage of it.

Goldhawg

iTrader: (7)

Well, since my Cutlass convertible goes 3800 lbs, think I may be better off with the dual plane. Especially since I can't see me really driving it that often >5500rpm....

Fast4a6

Is it possible that more pics of this car can be posted? id really like to see more of it.

speedtigger

iTrader: (16)

I think we did a pretty good job of this.

Good deal Goldhawg. Can't wait to see it rolling.

Mike52

iTrader: (1)

I put a link in my post #20.

Mike

rojs234

iTrader: (5)

I think that is the point we have been trying to get across. Build it to fit your needs and your type of driving. I spend very little time between 6000-6500 RPM. I will give up 15HP there anytime for 30-40 ft lbs of torque below 5000RPM.

Mike52

iTrader: (1)

It's a shame more people don't think about their engine's performance like you do, all to often, they get caught up in the 'numbers game' not realizing where the numbers mean the most for the type of driving they do. Well spoken.

Mike

Marcello7x

iTrader: (10)

I choose the single plane, and higher rpm cam. But it fits my car and driving style. My carcompleted will be sub 2500lbs, and lesser torque down low is beneficial because of traction. Plus i wot redline my dd 2-3 times a day atleast. Granted with 300 more hp and 1000lbs less it may happen less often when i daily drive my hotrod over the summer. In a heavyer car i would go for more torque down low.

NemeSS

iTrader: (127)

xpndbl3

iTrader: (23)

I still don't get how much part throttle torque people think they need

Goldhawg

iTrader: (7)

Well, I got an email back from MAST today; they do have the kit to use the truck throttle body on top of a 4 barrel intake like the first picture. The kit is $300, fuel rails $160, Oil pan $430. I want the GMPP manifold so I'm guessing 3-400. Mast says I can use factory ecm/harness modifying. So I guess send the harness to speartech for $400-500, and somewhere get a tune. I'm probably going with a set of stock manifolds (TBD but maybe the new camaros) plus the cost of the engine (thinking LY6 right now). Mast has a cam for this for $400. What other costs am I forgetting about (besides motor mounts)? I will use the truck accessory drive and a kwik ac/sanden comp.

Thoughts?

xpndbl3

iTrader: (23)

why not run a 4150 style throttle body if you're planning on using a carb intake anyways?

garys 68

iTrader: (1)

My initial thoughts are that it's a truck TB on an adapter.
A while back, there were knockoff carb style manifolds on ebay cheap. You might want to search here and see if you can find the vendors name.
Get some 1/2" aluminum and make an adapter. Some sheet metal to modify a carb air cleaner.