I have been reading a lot (maybe all, including the long discussions) of discussions on here that usually turn into carb vs efi in regards to single plane vs lt1 manifold, but not very much on the dual plane manifolds. I saw a few posts where people chimmed in and said that they were doing the dual plane conversion but never came back and said how it turned out. So I am wondering...

Assuming intake would be converted to run efi, and in an engine like mine for example that shifts at 6,500-6,600, would a dual plane work well? Would there be any gains over lt1? I see where the GM intake claims 30 ftlbs but who on here has done this and can say, yeah i picked up et,mph, or dyno results? The intake runners are longer on this manifold than the stock lt1 so I could see a potential for increase, but overall is it worth it?

Also thinking about the effective RPM range of the single plane manifolds. I have seen people do the single plane conversion(still keeping efi) and pickup a good amount of performance. But they are shiffting at 7k and above. I suppose I could spin that high but my last dyno showed power started to drop between 6,200 and 6,300 so I don't see a reason to. If a similar setup as mine went with a single plane, Do you think my RPM range would benefit from a single plane? I could stand to loose some torque if the gains up top are there, but again what rpm range could I expect?

I am not saying that I am going to do either one, though obviously thinking about it. I have just been reading for a couple days lots of info on this here and elsewhere and still have these questions.

Josh

 

I currently have the GMPP manifold on my engine. I will let you know how it performs. 6500 or even 7000 rpms should not be a problem. If your car will be street driven more than 50% (Like mine will) of the time go with the dual plane for added low end grunt. If it sees more track time go with the single plane for top end power. Most people you see run the single plane because they have race cars. Most people don't run carburetors on the street because of their poor gas milage, reliability or they're just FI snobs.

Edit: Also, your cam grind has a lot to do with where your powerband is. Hydraulic roller cams are usually crapping out by 6,800 rpms. You should invest in a solid roller valvetrain if you desire to rev any higher and still make power.

 

Already in the works on the solid roller but thanks for adding your advice. I don't plan on ever going above 6,800 rpm so good to know dual plane will probably be able to supply the air I need. Thanks for the input

 

And a little porting on the dual plane will help with the up top breathing. But 6500 RPM is usually when the dual planes give up. A sacrafice for torque vs. hp.

Personally, if you are staying EFI, I would stick with the stock manifold with a little porting. Dual planes are more beneficial for carbed engines. It provides a stronger signal to the carb and the curved runners create a better torque curve and throttle response. You don't have those issues with an EFI engine.

The stock manifold is a great piece that can be worked to do great and wonderous things!

 

I am staying EFI, and the heads and intake are ported. I was just wondering if maybe there was a benefit for my setup by going to dual plane. I have seen a few examples of EFI single planes being beneficial, but I don't make snappy desicions and thought I would get some feedback in regards to a dual plane. Thanks for your thoughts and anyone else that might have something to add.