Compound turbo setup with Holsets

[imagine02]

Curious to hear your thoughts on this setup.

Engine
M50B28
Shooting for 700hp

Small Turbo (basically an HY35)
CHRA: from 7 blade HX35
Comp Housing: from 7 blade HX35
Comp Wheel: from 7 blade HX35/HY35 (54/78)
Turbine Wheel: from HE351/HY35 (58/65)
Turbine Housing: T3 .63 AR
External Wastegate: 44mm

Large Turbo (basically an HX40 w/ HX50/52 size wheels)
CHRA: from regular HX40
Comp Housing: machined HX40
Comp Wheel: aftermarket billet 7 blade (67/89)
Turbine Wheel: from H1E (67/76)
Turbine Housing: T3 1.06 AR
External Wastegate: 44mm

[E36 HateR]

700bhp? Just use the hx40.

[somebody5788]

HX40 + E85 and push it hard.

[someguy2800]

Your big turbo is too small and your small turbo is too big to work effectively as compounds. Due to the low pressure ratios you would be running on both of them you will be off the map. Also I agree with the above, just get a single. I don't think compounds make sense until you need 40+ lbs of boost. Anything less than that and your not even at an efficient pressure ratio on either turbo.

[pbonsalb]

Compound turbo sounds complicated. Why do you need it? Is it a cheap way (recycling truck turbos) to get big power with good response? That is the only reason I would bother.

[Nutzy]

Too much hassle! Perry nailed it on the PR/map issue, too. If I were to compound anything, it'd be positive SC plus a turbo. But even then, could I be f'n bothered?

How about B30/B32 plus HX40?

[E36Mylo]

I don't think running compound turbos on these engines would gain any real benefits over many single turbo applications. Especially now a days when there's bigger turbos out there that give you small turbo spool but huge power.

[pbonsalb]

A very small number of people have done twin turbos. More complex than I want but if you get the turbos cheap and,are a fabricator, the extra work may not matter to you.

[Butters Stoch]

A very small number of people have done twin turbos. More complex than I want but if you get the turbos cheap and,are a fabricator, the extra work may not matter to you.

I have been debating doing this twin setup "just to do it" and "cause I can" type deal. The piping and the manifolds wouldn't be a problem, BUT....... There really is no benefit. With the setups out there now a days, like the poster above ^^ steed speed/9180 or whatever you can easily match whatever your goals are. Even the twin setups I have seen, have the same type of power band as the singles. Turbo tech has gone a long way.

[vollosso]

I have been debating doing this twin setup "just to do it" and "cause I can" type deal. The piping and the manifolds wouldn't be a problem, BUT....... There really is no benefit. With the setups out there now a days, like the poster above ^^ steed speed/9180 or whatever you can easily match whatever your goals are. Even the twin setups I have seen, have the same type of power band as the singles. Turbo tech has gone a long way.

Twin efr w/ mixed flow tho..


Sent from my iPhone using Tapatalk

[Butters Stoch]

Twin efr w/ mixed flow tho..

Sent from my iPhone using Tapatalk

Yeah, I'm totally waiting to see how that comes out. That could push me to do it.

[vollosso]

Yeah, I'm totally waiting to see how that comes out. That could push me to do it.

Tell him to get his *butt* in gear and skip the trip to asia. Twins > little boys...


Sent from my iPhone using Tapatalk

[imagine02]

My reasoning for compounds is because I want to build boost at low RPM, I have an assortment of Holsets available to me, I can do all the fabrication work myself, and I want to hang with the turbo V8 guys. Low RPM boost is wanted for tight and technical courses I race and drift on without having to shift. The high hp is wanted for larger and more open courses.

I realize a regular HX35 and HX40 are too close together for a good compound setup. That's why I was planning to make one a little smaller and the other a lot bigger. Even with those changes, do you think they are still too close to the same size?
My thinking behind all of this is that a 7 blade HX35 with an HY35 turbine in a small .63 AR housing will spool pretty quickly, but max out around 450-500hp.
While the HX40 with HX50/52 sized compressor and turbine in a 1.06 AR housing will spool pretty slow, but get me well over my 700hp goal.
I would go smaller than an "HY35" but the next step down for Holsets is an HX30 and those things are TINY. The oversized HX40 would rip it apart. People say that the little turbo wont get beat on by the big turbo in compound systems, but I know first hand that's simply not true.

If I didn't do compounds, I'd probably go with an HX40 with a 60/86 compressor and a 60/70 turbine in a .82 AR housing. Then use the "rally style anti lag" feature on MS. I'm thinking this setup could get close to 700hp with high boost.

I don't want to stoke higher than 2.8L because I feel the unbalance shortens the life of the engine. I plan on beating it pretty hard. We get a ton of runs at the drift events I attend.

[E36 HateR]

I had a 6664 hx40 at 26.5psi and e85 on a stock vanos m50 block and made 717whp and 550wtq .70ar t3. Switched to a 67x95 billet wheel and spool got much quicker.

[imagine02]

That's interesting. What were the boost levels throughout the RPM range?
All 3 of the turbo options I stated would have 7 blade compressors coincidentally.

[E36 HateR]

Hard to remember on that setup, with the m52 block i was seeing 22-23psi at 4100rpm in 2nd gear, and 30-32psi closer to redline, hard to tell without datalogs.