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Compound Turbo 6.5L

The Volvo KAD44 in my 27' boat is sequential compressor to turbo with the compressor kicking off as the turbo kicks in. Concept has been done before and compressor is more efficient at lower rpm.
 
I really thought about doing twin turbos on a 6.2/6.5 just because of being able to have two banks on each side of the engine. Wasn't sure what to do for the manifolds while staying away from getting something custom made (because of costing too much). Thought about taking a truck passenger side manifold and mounting it on the driver side, but you'd have to cut of the inlet flange where the crossover pipe mounts on because it would now be pushed front so much that it would be going past #1 cylinder on the left bank of the engine. Probably not the best idea and then I thought about using a van/hummer turbo manifold for both sides of an engine, making a pipe/turbo flange that would attach to the factory v-band outlet of those type manifolds. Few ideas.....oh and I think the HY35 is the best choice for keeping them the same on each side of the engine. And the 9cm2 exhaust housing is getting the job done for quick spooling too.
 
The HY35 was the exact turbo I had in mind too. Not too far off specs wise from a hx 35 but with a 9cm housing I think it would be just right for twins on a 6.5 that has enough fuel running through it. I will be on the hunt for some this summer. After the axle swap this will be my next project.

Hopefully someone can get a 454 head measured because if the exhaust ports are very similar, I would try out a 454 header. I was just looking at a set of rat rod headers on the big auction site. I would be willing to try them, just cut the mounting flange off and have one waterjetted for a 6.5 head. Flip the rat rod header upside down and either make a t3 adapter for the end or weld one on. The only thing I am thinking is what kind of angle the header would be at when flipped upside down, and possibly having to raise the turbos up higher than stock height to clear some obstacles.

Good discussion so far!!
 
If nobody has done the measurements by late may/early june I'll have the big block out of the truck to get exact measurements. Tomorrow I'll go measure while its in the truck.
 
The big block chevy heads have a staggered exhaust flange bolt pattern as well as the 6.2/5

I measured both sets of my bbc heads here by my computer desk a set of "840's" and a set of vortec's... both (which there shouldn't be a difference), but I measured both anyways becuase of the exhaust port size difference, have a 4.875" or 4-7/8" spacing.
My old 6.5 heads measured 4.75" or 4-3/4" spacing. All spacing measurements are from center to center of the exhaust ports. From what I just came up with, I would think if a nice "heavy gauge" flange was lazered out for the 6.2/5.... A person could probably cut the flange off from a bbc header and I'm sure there is enough "massage" room there to make them work. Would definitely be very interesting to see and or hear the results.

Also did forget to mention, that the bbc headers are a round tube where as the exhaust ports of the 6.2/5 are a tall narrow rectangular shape, for those whom may not have known.

Mike
 
Thanks Mike! Great work!

I would say there is probably enough massage room, especially since we would have to form the ends of the bbc header into the tall narrow rectangle shape like youmentioned. Now that I know they are close, I really wanna buy a set just to see.
 
finally got around to doing a quick test fit with the big block headers on a 6.5 block. As you can see in the first 2 pics the flanges are opposite of what we need but the tubes would need only a slight amount of tweaking to get them lined up.

P8130124.jpg


P8130123.jpg


In this pic the tubes would need to be reshaped and also cut down in diameter (these are flowtech long tube headers)

P8130126.jpg




If a company has a 'build your own header kit' for a big block chevy it could be adapted to a 6.2/6.5
 
Just want to throw this out there for discussion. It's not been lost on me that the 6.4L Powerbroke has a compound twin setup. And it's about the same size CID-wise. I've seen those turbos off the engine and they are pretty tightly packaged. Don't know if anything can be done with them, but it's an idea. I might play with it some day...if I ever get all the other things done to my rig that are already on the list!
 
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