Author Topic: Bigger Compressor housing and Wheel on stock T3 (Read 2669 times)

subsonic · « **on:** August 16, 2008, 04:57:35 pm »

Anyone here ever put a larger compressor housing on the stock vw T3? What effect did it have?

zukgod1 · « **Reply #1 on:** August 16, 2008, 08:16:09 pm »

If you don't change the wheel as well your not going to get anything more out of it.

subsonic · « **Reply #2 on:** August 17, 2008, 01:36:26 pm »

Well, I broke out the dial caliper and took some measurments.
The stock vw comp housing: .?? A/R
2" in (I.D)
1.4" out (I.D)

The stock vw comp wheel:
2.364" O.D
Blade width measured at the highest point:
1.379" / 1.378" (taller)
1.413" (shorter)

The merc comp housing: .42 A/R
2.80"in (I.D)
2" out (I.D)

Merc comp wheel:
2.364" O.D
Blade width measured at highest point:
1.590" (taller)
1.625" (shorter)

So the wheel and housing are definetly bigger. I dry fitted the bigger housing to the vw center section and it fit well. I have not taken the stock t3 apart yet so I can not compare the shaft dia. or lengths yet. Anyone know if they should be the same?
If I stay with the stock turbine wheel and housing should I be able to produce greater / cooler boost for the same given rpm range? Meaning quicker boost / less lag.

tylernt · « **Reply #3 on:** August 17, 2008, 07:55:50 pm »

Wouldn't increasing the compressor size while keeping the same turbine increase lag?

subsonic · « **Reply #4 on:** August 17, 2008, 09:40:45 pm »

As far as I understand it, the actual mass of the compressor wheel is still very small and should not be a factor in spool time. The bigger blades should move more air through the bigger housing. The turbine is not being changed. Same turbine wheel, same A/R housing. The exhaust gas should spool up the turbine wheel in the same amount of time as before. Perhaps if you went really big on the compressor side with a T3/T4 setup it might effect it,, but I am still staying on the small to medium size of the T3 family.
Anyone know what the A/R's are for the stock vw T3 turbine and compressor housings?

foxracer1 · « **Reply #5 on:** August 17, 2008, 09:41:26 pm »

I say try it. Besides having to fit the different sized inlet and outlet up it would be relatively easy to do then take it for back to back test drives.

Jet A · « **Reply #6 on:** August 19, 2008, 07:12:41 pm »

Quote from: "tylernt"

Wouldn't increasing the compressor size while keeping the same turbine increase lag?

It will increase lag, and could cause compressor surge.

If your compressor gets larger and the turbine does not, you will be decreasing the mechanical advantage across the turbo. which can cause the turbo. something to pay attention to if you do decide to do it.

You will experiance more lag, it is not all about rotational mass but about mass flow rate. due to a larger radius on the blade, you will be trying to push more air, which is more resistance, which will take longer to spool.

Dont get me wrong, i am ALL about experimentation. Just something to chew on while you ponder. And its really about what you do with your car.