Compound/Sequential Turbos....

JQmile

JQmile

Comp Diesel Sponsor
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Nov 19, 2006
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Ok, so I want to try something different with my 89 when I get it back on the road. I was thinking of a compound/sequential setup that basically bypasses the small turbo at full boost. The 'ol 14mm VE only has about 650-ish rwhp in it on fuel, so (don't laugh) I was thinking of a 49mm/71mm setup.

The idea is to be able to punch the truck and flash the converter (say 1,400rpm) and have everything come to life instantly. In playing with an Aurora 5000 as a single, it made 60psi at 2500rpm, so basically I need something from idle-2,200rpm where the 71 starts taking over. The large charger will be sized as a tight A/R single, and I'll bypass on the intake side too if I need to. I have a Steed Speed with an external gate, so drive pressure should be a non-issue, and a 71mm should make plenty of pressure ratio as a single for my needs.

So...thoughts? I was thinking of a GTX2967 as the small turbo.
 
Have you seen anyone do this before? I've wanted to try something like this for a while. It'd be a challenge to essentially build a check valve/wastegate for between the chargers though.

Ideally you'd want a check valve so it would open as soon as there's a vacuum from the low pressure turbo pulling more flow than the high pressure could handle. The first thing that comes to mind is a piston style spring valve, but I'm not sure the size you'd need to make that work correctly.

Now, what you could look at doing that might be easier, would be grabbing a valve off of an EGR truck and have it electronically open at a certain boost pressure. Use that valve in parallel to the high pressure turbo (like you would wastegate the other end) so you only need one air filter.

Take all this with a grain of salt because I'm overseas and may have considerable jet lag. ;-)
 
BMW 3 litre turbo diesel does that. Might pay to look at the way it works. I think it's a fair amount of work, but if done properly would be ideal to drive.

Andy
 
Or what about an e gate or two in the piping off the primary compressor. There's also the option of using a little smaller, but similar flowing primary like an s467 , gtx4294r, or maybe one of those new s369sxe's. Those are all near 100lb/min chargers that'd light faster than a 471. I feel like a gtx3076r may also be a nicer secondary. It's 60mm turbine might be a better match for the diesel than the 56mm turbine on the 2976r. JMO though. I know someone with a gsxr1000 drag bike with a gtx3076r, and apparently that size is like the go to for those bikes
 
JQmile said:
Ok, so I want to try something different with my 89 when I get it back on the road. I was thinking of a compound/sequential setup that basically bypasses the small turbo at full boost. The 'ol 14mm VE only has about 650-ish rwhp in it on fuel, so (don't laugh) I was thinking of a 49mm/71mm setup.

The idea is to be able to punch the truck and flash the converter (say 1,400rpm) and have everything come to life instantly. In playing with an Aurora 5000 as a single, it made 60psi at 2500rpm, so basically I need something from idle-2,200rpm where the 71 starts taking over. The large charger will be sized as a tight A/R single, and I'll bypass on the intake side too if I need to. I have a Steed Speed with an external gate, so drive pressure should be a non-issue, and a 71mm should make plenty of pressure ratio as a single for my needs.

So...thoughts? I was thinking of a GTX2967 as the small turbo.
Click to expand...

Pius designs his systems with a small secondary and multiple wastegates.
 
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