compound turbo/super charger results from hotrod
02-12-2009, 10:55 AM
#22
I heard rumors that there is a compound setup in the works on here, but I don't know who it is... 
I think parish is right though. It's not for making peak power, as I feel the same way. The peak numbers will be slightly less then a big turbo alone, but the blower "should" increase the bottom end ALOT and help to spool the turbo up faster. One will help the other, first getting the turbo up and spooled with the extra air flow from the blower and then with top end air flow with he turbo over what the blower could do on its own. The power under the curve will be much greater and should make for a much faster "street" setup in something with traction.
The only still unknown to me is the affect on the blower having to "suck" though the intercooler and turbo to get its first breath of air when you first go WOT until the turbo get some spool. I know blowers don't like inlet restrictions.
I think parish is right though. It's not for making peak power, as I feel the same way. The peak numbers will be slightly less then a big turbo alone, but the blower "should" increase the bottom end ALOT and help to spool the turbo up faster. One will help the other, first getting the turbo up and spooled with the extra air flow from the blower and then with top end air flow with he turbo over what the blower could do on its own. The power under the curve will be much greater and should make for a much faster "street" setup in something with traction.
The only still unknown to me is the affect on the blower having to "suck" though the intercooler and turbo to get its first breath of air when you first go WOT until the turbo get some spool. I know blowers don't like inlet restrictions.
Last edited by kbracing96; 02-12-2009 at 11:32 AM.
02-12-2009, 12:03 PM
#25
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You couldn't/shouldn't intercool post turbo and pre-blower. That would be nice, but you're right, a positive displacement blower does not like inlet restrictions. By the same token, a blower doesn't like an exhaust restrictions either, which a turbo provides. You'd need to run meth then since the Radix IC is not up to the task of cooling air from compounding sources.
With that said, the dynamics of the fuel/air/exhaust needs to be understood before a determination can be made.
What kind of cam does Hellion use? I'm thinking that with any significant overlap, you'd have huge reversion effects due to everything backing up in the turbine. I don't know though, because the added help of the blower might help push everything through.
Did that article include a boost vs. rpm graph? That would help a lot. I also think doing the tests on a free spin dyno was a waste of time. Typical HRM.
There's no doubt though that twin charging can make big power, but I think it comes in the form of high boost levels achieved at lower rpms. Not necessarily from the compounding of boost.
Check this out:
http://en.wikipedia.org/wiki/Lancia_Delta_S4
With that said, the dynamics of the fuel/air/exhaust needs to be understood before a determination can be made.
What kind of cam does Hellion use? I'm thinking that with any significant overlap, you'd have huge reversion effects due to everything backing up in the turbine. I don't know though, because the added help of the blower might help push everything through.
Did that article include a boost vs. rpm graph? That would help a lot. I also think doing the tests on a free spin dyno was a waste of time. Typical HRM.
There's no doubt though that twin charging can make big power, but I think it comes in the form of high boost levels achieved at lower rpms. Not necessarily from the compounding of boost.
Check this out:
http://en.wikipedia.org/wiki/Lancia_Delta_S4
02-18-2009, 07:59 PM
#27
TECH Veteran
As I was reading that I thought something sounded off. To do that test and not do it on a load bearing chassis dyno or an engine dyno seems likey they only did it to make the numbers really shine. On an engine dyno the twins without the blower would have likely made the same or more by actually getting them spooled. On a Mustang chassis dyno even the turbo's would have spooled and made the boost much earlier making the numbers very close. At the track where you'd be pre-loading on the converter before launching and getting full boost early on I don't think the twins would be slower at all. On top of that past the first 100 feet or so there would be no gain from the blower.
