My compound turbo set-up

[DashLaflash]

So is this a valid option on a daily driver? I haven't read through the thread in a while but I remember you mentioning earlier running methanol or e85 to help cool things since you don't have two intercoolers. Is it possible to run it at like 20 psi on pump gas and not have underhood temps skyrocket in mid-summer?

 

[99gst_racer]

Yes, I don't see any reason why a person couldn't daily drive on a set-up like this. It's very street friendly and throttle response is excellent. Charge temps are about the same as a single turbo set-up. I used meth injection to slow the rate in which the IAT's heat up, but it functioned great without the meth too. 20psi is definitely doable on pump gas, even without water/methanol. But it's also alot of money and work to only run 20 psi on it. By nature, it's meant to be pushed much harder than that.

 

[DashLaflash]

Well thats good to hear. I was thinking of building one of these in a couple years. If you don't mind mind me asking how much did you end up spending on materials for the manifolds and downpipe? I will be looking forward to your new set up and following the progress.

 

[99gst_racer]

I never kept track of the cost of materials the first time around, but I definitely will this next time.

It really depends on what materials and how much of them though. And that will vary from each individual set-up. My new set-up will use more expensive materials, but much less overall material, so it will probably end up costing less.

 

[turbotalon1g]

Paul I had a good idea I think.

what about an evo 8-9 16G with a 6262 or 6765? The 10cm housing should provide decent top end.

 

[99gst_racer]

Not a bad idea. I almost went with the EVO 8/9 turbo for my new build. The only thing that I didn't like about it is the divided turbine housing. Twin scroll is definitely not needed with compound turbocharging, and it makes it much more complicated to add a large external wastegate.

So I opted for the more user friendly T3 10cm td05 housing.

 

[turbotalon1g]

Any more word on this?

What do you think the limit of the 16G is?

Sorry, I'm bored and thats just bad for everyone at this point.

 

[99gst_racer]

Nothing new to report.
I haven't begun building the next one quite yet.

I'm not sure what you mean by the "limit of the 16g". It's still physically limited just the same as any other 16g... If your question is "what's the most power you can get out of a compound set-up using XX turbo and a 16G?", then the answer depends on a host of other variables such as the size of the larger compressor, the PR each are running at, the rest of the engine's build, etc...

 

[turbotalon1g]

^Oh ok.

So it would depend on how much airflow the big turbo would be feeding the 16G with?

Sorry, I'm just bored and daydreaming.

 

[99gst_racer]

Yup. A 16g paired with a 42R very well be capable of 900-1000 whp. It heavily depends on the size of the larger turbo.

 

[kicker91laser]

I am really looking foward to seeing this next setup evolve Paul. I am wondering if the physical size of the 16g would evetually lead to an airflow cap, even with a larger seconary. I am planning to do a compound setup on my next rwd build, I've been thinking of using an hx35 w/bolt-on housing and a t6 s475, on a 2.3. Where are you getting the larger .120" ss tubing and bends?

 

[turbotalon1g]

I thought the 16G would hurt the top end, I'm thinking something like a E316G fed by a 6765. Which turbo turbine becomes a restriction first?

 

[schroder]

The big turbo. The small turbo is fed air at a lower than atmospheric pressure, so it just continues to compress the air. When the big turbo chokes is when the system chokes. If I remember everything from what I was speaking with Kevin about correctly.

*Also, referencing the Holsets...is this with the BEP housing? What if you used the factory housing on the HX35 instead of the BEP....great top end power and then you'd have the compounding to help spool, right?

 

[Kevin Jewer]

Yes, the atmospheric turbo is the limiter. The small turbo will take whatever the big turbo gives it. Where you set the small turbo for PR just determins the PR the big turbo will need to run at to max out. In other words, a higher PR on the small turbo makes the motor seem bigger to the big turbo, so it will max out at a lower boost. A lower PR on the small turbo will have the opposite effect. The small turb's PR is effectively variable displacement.

I personally don't feel that the small turbo's turbine section is a limiter whatsoever if it's not boost creeping, which by definition means all excess is being properly wastegated. Big turbo turbine might be even more important, since its back pressure will increase the total backpressure by a factor of the small turbine's pressure ratio. In other words, 10 psi back pressure from the big turbo could be 15 psi additional back pressure for the system as a whole, for example. But none the less, lower BP from the small turbine will result in lower BP overall, so it's still important.

 

[turbotalon1g]

Thanks for that post, if this is getting too OT. We could start another thread.

I'm trying to get a solid understanding of this.

 

[schroder]

...Thread is on Compound Turbos...I dont think he'll mind

Any insight on the HX35 or HX40 idea...just using the hotside from Holset, not BEP?

 

[kicker91laser]

...Thread is on Compound Turbos...I dont think he'll mind

Any insight on the HX35 or HX40 idea...just using the hotside from Holset, not BEP?

Using the holset as the small or big turbo?

 

[schroder]

As the large turbo...Everything from my understanding is that the holset spooled very quickly, but with the BEP housing. Using the housing from Holset would free up the exhaust side to act as a large turbo would, right? Use a 14b or 16g for the small, and a TRUE holset for the big turbo, either 35 or 40

 

[kicker91laser]

You would definately want to use the larger Holset turbine housing, the bolt-on housing would be too small imo.

 

[schroder]

I already knew the BEP housing was too small...I was trying to find out info or opinions on the Holset hotside on either one of those turbos...or what power they would be rated for with those hotsides?

 

[Kevin Jewer]

IMO, run the biggest hotside possible on the big turbo. My big turbo runs a T6 1.32 housing with a 96mm turbine wheel (). Running a smaller turbine side on the big turbo would be counter productive.

 

[schroder]

Agreed. I just was really curious to know what spool times are on a "stock" holset...either hx35 or 40 honestly. I know they are "awesome" with the BEP housing, but I already have an Evo 1 16g...no reason not to take advantage of it and then just bolt on big power By bolt on, I mean...fabricate, build, text, and cross fingers for everything else Thanks again for all your help, both here and on HRCS.

 

[Pirrofab]

holset 35 in stock housings are seeing full spool by 3800-4k. sometimes sooner in well built setups. The bep bolt on housings see spool a few hundred rpm sooner. IMO pairing one of these with a 14b or 16g wouldn't really be worth it. It would just make to small of a power increase over what a 16g is already capable of. If a holset was to be used a hx-52 with an evo316g would be the ticket, or hx-55. The HT-60 is just way to large.

 

[hubz91talontsi]

holset 35 in stock housings are seeing full spool by 3800-4k.

Depending on which housing your hx35 has i suppose..

 

[b00st3d4g63]

This thread is awesome. I wish I had the money and skills to do this.