Why do the HX55's spool slow when they have roughly the same size wheels as an HTT 64/71 ??

Is it that you cannot get a small enough exhaust housing? Is the shaft a lot bigger? Are the wheels just heavier? What makes the S300 based 64/71/14 so much faster to spool than HX55?

http://cgi.ebay.com/ebaymotors/HUGE-...spagenameZWDVW

According to this ebay listing, this turbo has 65 mm compressor bore so 64mm compressor and 72mm exhaust turbine wheel bore so 71 mm turbine.

 

Its the housings. Rowland ran a 55 with a small housing with good results before, while just about everybody else I've talked too had bigger housings and couldn't spool it well. I see some 19's in the casting of that holset, so may thats a 19 cm? JR Adkins was the one pushing the custom 55's and the price of the smaller housing was pretty high.

 

The exhuast housings are usually big unless some one worked it over.

 

And to correct myself, those 55's I was referring to were "baby 55's", some sort of hybrid.

 

I have one of the little 55's. It is actually a H2E/HX40 because i had to have it rebuilt. Since the rebuild it is now in about a hundred little pieces. Good street turbo but not good for pulling on a 12valve with a lot of fuel. It oversped the compressor and blew the many pieces of the wheel through the comp. housing and broke the cartridge in about 4 peices. So basically i have a good tubine housing left. The comp. nut is still on the shaft so that might be good too. LOL Tim

 

That turbo is just like a HX52 if not one , most 55s use the same inducer but the turbine is 77mm instead of 71or2 like the 52s are ... email them and ask what # is stamped inside of the turbine housing 52s are usally 16cm