Anyone run twin stock turbos in paralell?

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b4ctrooper

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Had a discussion with a friend today on this. It's done all the time with gassers. How about 2 stock turbos on an engine that feed 3 cylinders each? I know, quite a good amount of fabrication, but has anyone tried that before? We figure there would be a good amount of lag, but once boost builds, it should be able to move a good amount of air. Seen plenty of twins setup in series (one turbo feeds another turbo), but never one this route.
 
I personally know of 1 person that tried this.

He only described it as "undriveable."

Pretty straight shooter. He has compounds now, and has told me several times he wouldn't even consider trying something like that again.
 
it would work on a V motor but I dont see how it would work on an inline motor.
 
MD-LUCKY said:
I personally know of 1 person that tried this.

He only described it as "undriveable."

Pretty straight shooter. He has compounds now, and has told me several times he wouldn't even consider trying something like that again.
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What do you mean undriveable? Was it just unable to build boost, or something else?
 
you would have to use 2 turbos a lot smaller than the stock ones or the like said above the lag would be terrible.
 
Lag.

Said he couldn't spool the turbos at all. Put your foot to the floor, EGTs would skyrocket, and boost would just barely budge.

I don't know if he has any pictures or not.. I'll find out.
 
Take split housing plates, that shuts off one of the volutes, so only one charger gets fed on the exhaust side, and then get a charwin valve to shut off the same chargers inlet. Once boost comes up, then open both valves.
 
I guess I should feel blessed that I have a somewhat innate understanding of all things mechanical, but it still baffles me that people think that putting twice the turbocharger on a vehicle will somehow make it twice as powerful...

take a turbo off of an engine roughly twice the size and twice the horsepower as one of these engines... something like an S475 and hang it on your truck and see how well you spool it...

gassers don't do it all the time... yes, they run parallel twins often enough, but they are properly sized... they don't run twice the turbocharger necessary
 
MD-LUCKY said:
Lag.

Said he couldn't spool the turbos at all. Put your foot to the floor, EGTs would skyrocket, and boost would just barely budge.

I don't know if he has any pictures or not.. I'll find out.
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How would egts go threw the if there was no boost. If the fuel isnt burning then where is the heat coming from?
 
if it tells you anything on my 3cyl 4000 ford diesel tractor thats 201ci, i can get 7psi from a hx35. and i can get 11-12 out of an hy35. it turns close to 3k and has 5 hole 10 nozzles and a turned up pump.
 
HIGH TECH RAM said:
How would egts go threw the if there was no boost. If the fuel isnt burning then where is the heat coming from?
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The fuel still attempting to burn as it exits the combustion chamber... or the fuel that burned to late in the powerstroke to increase power?
 
I think it is because if the turbo's are not spooled the motor can not breath so that heat builds up, that causes EGT's and cylinder temps to go up.
 
Forrest Nearing said:
I guess I should feel blessed that I have a somewhat innate understanding of all things mechanical, but it still baffles me that people think that putting twice the turbocharger on a vehicle will somehow make it twice as powerful...

take a turbo off of an engine roughly twice the size and twice the horsepower as one of these engines... something like an S475 and hang it on your truck and see how well you spool it...

gassers don't do it all the time... yes, they run parallel twins often enough, but they are properly sized... they don't run twice the turbocharger necessary
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Ok. No need to treat people like they're stupid. Nothing we planned to do, it was just a hypothetical discussion. We did know there would be crazy lag with original cummins turbos. What I should have said was 2 small turbos. Hell, I have several sitting around from turbo 4cyl chryslers if I even wanted to bother. Like I said though, this idea came up in conversation so I figured I'd see if anyone had an opinion on it. We don't plan on trying it (at least not right now).
 
b4ctrooper said:
Ok. No need to treat people like they're stupid. Nothing we planned to do, it was just a hypothetical discussion. We did know there would be crazy lag with original cummins turbos. What I should have said was 2 small turbos. Hell, I have several sitting around from turbo 4cyl chryslers if I even wanted to bother. Like I said though, this idea came up in conversation so I figured I'd see if anyone had an opinion on it. We don't plan on trying it (at least not right now).
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ahh, I thought you meant two Cummins turbo...

now, here's the problem w/ a couple smaller turbos on one of our engines... these engines have very poor air flow characteristics through the cylinder head and a camshaft that also neuters flow. we're working with engines designed to turn 2500rpm at 200-300hp... when you're asking the thing to turn another 1000-1500rpm and double the power (or more), you need more air, and other than serious head porting and a camshaft, the only way we can get more air in is to increase pressure...

we need high pressure ratios and we need turbos that operate efficiently in at those pressure levels.

those old Chrysler T3's run out of efficiency probably around 20psi...

the reason we compound turbos on these engines is to get high pressure ratios without superheating the air... it's tough to find a small enough compressor that's efficient at 50-60psi, so we share the load between two compressors so that they can both operate efficiently and the result is good dense air that isn't ultra-hot :)

now, if you have an efficient engine w/ a heavily worked head and a camshaft and all that and can make 600hp at 40psi, yeah, you could run a pair of smaller turbos, but the added weight, complexity, and loss of underhood space would have no benefit over a properly sized single.

on a V engine, the underhood packaging often lends itself to a turbo hanging off of each bank. I just don't see any good reason for parallels in a single stage on an I6.

now, I've thought about running parallels as the first stage and feeding them to a single 2nd stage... it would work... but, again, the complexity of the system would make one large turbo make more sense than a pair of smaller ones IMO
 
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