Comp size VS turbine

biggy238

biggy238

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Aug 3, 2008
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What functionally happens when the compressor inducer is larger than the turbine exducer? I've been told the 351 is a 60/60. What would happen if the compressor were a 62?
 
just looking at one side of each wheel isnt really going to tell you much. the s300's surge with a 64/65 and 66/71. with the holsets people run 60/58 hx40/hx35 hybrids without surge.
 
Rollin Coal said:
just looking at one side of each wheel isnt really going to tell you much. the s300's surge with a 64/65 and 66/71. with the holsets people run 60/58 hx40/hx35 hybrids without surge.
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yup, i have had surge with a 62/65/12 while towing at about 10-20psi and i have no surge what so ever with my 60mm h1e/h1c hybrid.
 
okish said:
yup, i have had surge with a 62/65/12 while towing at about 10-20psi and i have no surge what so ever with my 60mm h1e/h1c hybrid.
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So the answer lies in the drive pressure applied and the size of the exhaust housing.


I was just wondering why a 62mm wheel couldn't be applied to an he341 or 351 and have a nice little turbo. Maybe run a slightly larger exhaust housing.
 
Could it be the stress on the exhaust side to turn a larger mass on the intake side? Assuming stock head and head restrictions. It's all about turbine speed and getting some flow.

I bet all bets are off getting the flow up there with ported head and a massive gate. So when the flow is not as much as a restriction you can get the turbine speed up faster (with less boost) and easier with a tight housing and just vent when drive is to what ever point you want. I'm guess here, but this is what I think I see on the banks stuff, tiny turbines and larger compressors and massive gates. I'm sure spraying 15 bottles per pass has something to do with that combo as well.

That sound about right?

naturally most of use won't have a full port job and need to deal with higher drive and boost pressures to make ends meat.
 
No surge here with either a 62/65/12, 62/71/13, 66/71/13, or a ksb-1. The 66/71/13 is the only one I've never driven without the cam. The other three I've driven on a stock cam.
 
does anyone know if holset has a 62 wheel that could be applied to an he341?

Jason, I simplify it to the point that a larger wheel can apply more torque. If the turbine is smaller than the compressor, then the drive pressure has to stay higher than the charge air side or the turbo will bark. I'm just curious what size exhaust housing could be run before the sizing becomes prone to surge or backflow? Maybe id would be more accurate to use aspect ratio?
 
I have heard turbine blade pitch and count is of most importance with the flow/DP in regards to surge. $.02
 
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