I'm building a twin turbo Datsun 240z. I wanted to do something different. I was inspired by a Cougar build on this site where the owner built what was basically a dual quad tunnel ram from a Holley hi ram. I thought that thing would be awesome with twins....but decided I dont want it through the hood like that. So that led me to the Edelbrock Cross Ram. Which leads to my question. I am concerned that each turbo feeding it's own plenum would make it difficult to keep everything even pressure-wise. 2 maps, 2 boost controllers, etc....I was planning on solving that issue by fabbing a crossover/equalizer between the back of each plenum and running my map off of that. Does anyone see a problem with that? Would that create other issues that I'm missing?

 

Defeats the purpose of the manifold to install equalizers. Use Dual WB02's. Find your leanest bank and use the readings off that side for the MAP. Then read the plugs and use an ECU that's capable of adjusting fuel trims per cylinder. It will be fine. ESP with something like E85 tuned on the rich side.

 

Edelbrock built in equalisers to theirs because in testing cylinder distribution was all over the place. Although other factors could play into that too.

But really...you're dreaming up problems that you do not need to.

2 map sensors and boost controllers ????? seriously ? can't quite think of the correct emoji for that

 

I didnt know Edelbrock had them cast in. Knowing how piping and back pressure and a myriad of other things an affect boost pressure I was worrying that I could have a significant pressure differential between the two sides. Thanks.

 

 

I think RH did have the intake in one of his tests ? Can't find it though.

It definitely looks cool, but on a practical and performance level it just doesnt shine above anything that's already out there.

 

I thought Richard feed them with a single, cant remember-i'll see if i can dig it up.

 

Really doesnt matter one way or the other.

But the two blades will be of no actual performance benefit

 

Use an equalizer. You'll lose some of the whole idea behind the dual plenum, but that isn't its only purpose.
Dual plenum allows for increase plenum volume, reduced runner bend radius, and ideal runner length in comparison to a single plenum.
Trying to match plenum volume while still matching runner bend radius and runner length with a single plenum would typically require it to be placed really high above the engine, much higher than a Holley Hi-Ram.

 

I have experience running a dual plenum crossram though with carbs. Most of the lessons will benefit an injection set up too. My cross ram on my sbc was a wieand and it didnt work for **** at first. Idled fucked up wouldnt pull the secondaries open for **** till high rpm. You could watch the damn vacuum gauge bounce between 0 and 8 pounds back and forth at idle. it got better reved up but still low vacuum even when it was basically running on only the front of both 4 barrels. The single four barrel it replaces made more power. Almost gave up but im hard headed so i decided to try to share the vacuum signal or in other words make a blance tube. First i tried running the two pcv valve ports on the back of the holleys together thinking it would help balance things. Made the idle better but the secondaries still wouldnt open and low vacuum. Put a 3/4 heater hose fitting between the plenums and a 2 inch peice of heater hose and it was way better. So i bite the bullet and took it down and had a 2 inch piece of square tubing welded in between the plenums and it was awesome. Idled good and secondaries worked pretty good. Then on a wild hair i threw a tunnel ram and two 660 center squirters on the engine and it put that crossram to shame that quick. More power, better idle. Just hated cutting the hood. All of the signal issues where because of the divorced plenum. I think it could be controlled with efi but why when a balance tube makes it super easy. Then again screw that crossram and get a high ram in my opinion. If you want dual throttlebodies get two side plenum intake tops, split em down the middle and weld them together and make a dual throttlebody high ram that feeds from each side. In fact i have been contemplating that exact set up for awhile not for performance gain but just cause it would look awesome and be different. that in my opinion is almost as important as speed. But i think that might be an unpopular opinion these days with alot of folks. I just always liked popping the hood and people going wtf. Everyone has a sbe turbo ls these days. You gotta blow a hole through the side of the box if you wanna stand out.

 

Make it composite and maybe someone would use it for a stoker NA build.

 

Merge the charge piping with an "x" pre TB. Would be a lot easier.

 

That sounds like the easiest way to go.
Thanks to everyone for the info and advice.

 

You will always get an "unstable" signal if you take a reading from a single runner, that's always been the case and there are tuning methods to sort this. ( ie, ignore MAP below certain loads and run TPS as main load parameter in those areas ). No different than EFI tuning ITB's, but that is very different to what Edelbrock are offering here.
The Edelbrock does already link both plenums anyway as already said.

 

Thanks! :-D

Andrew

 

Almost!

 

Hey, thank you! I loved reading through your build. Very well done. I know it takes a ton of time to document, organize, and post up all of the details of a build, much less the time actually working on the car! It is much appreciated.

 

wouldnt a dual in/out intercooler achieve the same thing?