Hey guys i done a seach but nothing i wanted to know was in there.
I want to know if you run a turbo say t04 with a rear housing with a .96 a/r and then u run a bigger turbo say a t88 with a .96 a/r rear housing will they both spool at the same time or not as the a/r is the same but one turbo is twice the size?


cheers guys

 

No the larger turbo will spool slower simply because of the larger mass of the compressor wheel....... actually the hot side will be bigger in your example as well.

 

You could go on garretts website and pull up maps for both turbos and compare them or contact forced performance. ANY time i've had a turbo related question, they've always been able to give me a quick answer and point me in the right direction.

Ranzo answered what i was trying to but for future reference, i'd thought i'd share a bit.

 

Smaller AR = quicker spool, more restrictive exhaust flow, higher EGT's, higher exhaust pressure, more cross flow if you have a port with overlap. Can cause boost to drop off in higher rpms.

Smaller AR = slower spool, less restrictive exhaust flow, lower EGT's, lower exhaust pressure, less cross flow.

You need to find a balance between spool and top end.

 

so even though they have same a/r they will spool at different times cause its bigger?

 

If you want to know more then buy the HP book called Turbochargers by Hugh Macinnes it has all the information you will need! cheers David