I just realized I made a mistake explaining the pressure ratios. A turbo making 30 pounds of boost would be working at a 3:1 pressure ratio, not a 2:1 as I said in the video. Same principles apply, I was just doing the math wrong.
Cool project, looking forward to seeing it installed and running! And congrats to Zach. My friend became an electrical engineer a year ago and he has a great job now, and he does cool stuff with electronics at home, too.
Turbos don't run from cold side to hot side so not so much as a multiplayer. Hot side will always run more pressure unless you have some magic vudo. Without drive pressures you have no boost pressure. Fyi. Clean compound setup tho
Since the smaller turbo is the limitation on the max airflow,why don't you cool down the air exiting the first small turbo before compressing it again. compressing cold air is more efficient than compressing hot air. Density is more important than pressure since the flow is limited by the small turbo. You could use less pressure ,have a better spool up speed,and better efficency. you would have the max density for the max flow for your set up. the bigger turbo will not help for pulling flow,so the colder air you give to it,the better it will be.
michaelovitch Cooling the charge between stages has been done and does have benefits but IMO the complexity outweighs the benefits in this case. I think you have it backwards though, the big turbo compresses the air and then the small turbo compresses it further. So you would have to cool the air after it comes out of the big turbo before it goes into the small one, since the bigger turbo is working at a lower pressure ratio it isn't heating up the charge air as much as the smaller turbo. Since most of the heat comes from the second stage of compression the intercooler does a great job at cooling everything down before it goes into the engine.
I have a similar set up. Still reachable from the top. Just depends on what piping kit you go with. You could make it more room if you build your own kit
This looks amazing , im not an engine builder but is the system not slowed by whatever the slowest turbo is? 60psi does sound like a hell of a lot though , most of the street cars i have herd of were running somewhere around 10
GamersBar The smaller turbo does limit the power potential up top but the gain in low end power is well worth it compared to a big single in my opinion.
The secondary turbo should be smaller than the primary because it is working with pre-compressed air. And the turbo lag will be negligible and the efficiency would be higher. Smaller turbos take less power to spool up and quicker. And the smaller turbo produces much more toque on lower RPMs. people always over size the turbos....
i would have thought the system would be restricted by the total amount of air the smaller turbo can flow, or does this compounding actually increase the efficiency of the turbo? Interesting stuff...
TrueBlueEG8 In a compound turbo setup the small turbo can support more power than it would as a single turbo and the big turbos power potential is limited by the smaller turbo. Essentially you're getting quicker spool up at the cost of more power up top than if you ran the big turbo as a single.
I think I can see the potential benefits on a big heavy diesel engine. Maybe it would work better with equal size turbos? I am sure there is a perfect combo of turbo size/flow rate or mixtures of ideal compressor/turbine wheels and hose/housing diameters, it has me interested
TrueBlueEG8 These two turbos are pretty well matched in a compound arrangement. The HE351 can support about 700hp as a secondary and the S475 can support just over 700hp as a primary. I'm not the best at explaining why it works so well but there's a good reason most high horsepower diesels use a compound turbo setup.
The bigger turbo can just blow through the smaller turbos compressor housing... Even once the smaller turbo exceeds its compression map efficiency sweet spot the bigger turbo will just keep pushing more air beyond that smaller compressor housing......so yeah it just blows through it 😆 brutal for the intercooler but...meth injection might cool it off.
I just realized I made a mistake explaining the pressure ratios. A turbo making 30 pounds of boost would be working at a 3:1 pressure ratio, not a 2:1 as I said in the video. Same principles apply, I was just doing the math wrong.
did you make your own piping?
Cool project, looking forward to seeing it installed and running! And congrats to Zach. My friend became an electrical engineer a year ago and he has a great job now, and he does cool stuff with electronics at home, too.
Super clean compound setup
Very cool....keep us posted!
More to come!
Gonna be badass!
Yeah Buddy!!!
Where did you buy the materials vbands pipes etc for the hot pipe and tubing for air filters?
Cant wait too see how hard the oil filter is to get off after lol.
Facts
Sweet setup. Is that the puke/blow-by tube going into the oil fill cap or is there a bypass filter somewhere over there?
Turbos don't run from cold side to hot side so not so much as a multiplayer. Hot side will always run more pressure unless you have some magic vudo. Without drive pressures you have no boost pressure. Fyi.
Clean compound setup tho
Since the smaller turbo is the limitation on the max airflow,why don't you cool down the air exiting the first small turbo before compressing it again.
compressing cold air is more efficient than compressing hot air.
Density is more important than pressure since the flow is limited by the small turbo.
You could use less pressure ,have a better spool up speed,and better efficency.
you would have the max density for the max flow for your set up.
the bigger turbo will not help for pulling flow,so the colder air you give to it,the better it will be.
michaelovitch Cooling the charge between stages has been done and does have benefits but IMO the complexity outweighs the benefits in this case. I think you have it backwards though, the big turbo compresses the air and then the small turbo compresses it further. So you would have to cool the air after it comes out of the big turbo before it goes into the small one, since the bigger turbo is working at a lower pressure ratio it isn't heating up the charge air as much as the smaller turbo. Since most of the heat comes from the second stage of compression the intercooler does a great job at cooling everything down before it goes into the engine.
I have a similar set up. Still reachable from the top. Just depends on what piping kit you go with. You could make it more room if you build your own kit
Nice.
Cool !
Thanks for the comment!
This looks amazing , im not an engine builder but is the system not slowed by whatever the slowest turbo is?
60psi does sound like a hell of a lot though , most of the street cars i have herd of were running somewhere around 10
GamersBar The smaller turbo does limit the power potential up top but the gain in low end power is well worth it compared to a big single in my opinion.
The secondary turbo should be smaller than the primary because it is working with pre-compressed air.
And the turbo lag will be negligible and the efficiency would be higher.
Smaller turbos take less power to spool up and quicker.
And the smaller turbo produces much more toque on lower RPMs.
people always over size the turbos....
late to post; you're correct
i would have thought the system would be restricted by the total amount of air the smaller turbo can flow, or does this compounding actually increase the efficiency of the turbo? Interesting stuff...
TrueBlueEG8 In a compound turbo setup the small turbo can support more power than it would as a single turbo and the big turbos power potential is limited by the smaller turbo. Essentially you're getting quicker spool up at the cost of more power up top than if you ran the big turbo as a single.
I think I can see the potential benefits on a big heavy diesel engine. Maybe it would work better with equal size turbos? I am sure there is a perfect combo of turbo size/flow rate or mixtures of ideal compressor/turbine wheels and hose/housing diameters, it has me interested
TrueBlueEG8 These two turbos are pretty well matched in a compound arrangement. The HE351 can support about 700hp as a secondary and the S475 can support just over 700hp as a primary. I'm not the best at explaining why it works so well but there's a good reason most high horsepower diesels use a compound turbo setup.
The bigger turbo can just blow through the smaller turbos compressor housing...
Even once the smaller turbo exceeds its compression map efficiency sweet spot the bigger turbo will just keep pushing more air beyond that smaller compressor housing......so yeah it just blows through it 😆 brutal for the intercooler but...meth injection might cool it off.