Quote:
Originally Posted by Jetmugg
Thanks for the info regarding the HY25W. I'll start keeping my eyes open for one. Would there be any benefit to switching the turbo by itself? I'm interested in improving the performance of this car, but want to understand the logical progression of improving the performance.
I've read this forum and the STD forum quite a bit, but there are still a lot of details regarding the most logical sequence of events to improve performance on a mild budget.
I know there is some development work going on with respect to a USA source of pump modifiers, but I haven't seen anything reliable or concrete yet.
If swapping the turbo without any internal pump modifications will yield results, I'd be happy to do so. I'd also be willing to keep my eyes open for one of these turbos to have "on the shelf".
Thanks,
SteveM.
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Good questions. Holset was generally considered to be about 10years ahead of Garrett when our cars were made, this is no longer the case. The compressor wheels tend to be generally the same configurations however if you look at the turbine wheels you can see they are quite different. I think the only way to know for sure is to try!
Some musings from other sites:
Holset turbos VS Garrett turbos - Columbus DSM Forums
Quote:
•Holset's don't spool slow. They spool faster than their garrett or mitsubishi counterparts. Diesel exhaust is cold and slow moving.
•The holset turbine wheel is a work of art. It has been shown to flow very well in a very small turbine housing. For example the hx40 turbine wheel in the small .55 ar bep bolton housing flows as much as a garrett gt35r turbine wheel in a larger .63 ar garrett t3 turbine housing. The hx40 with this configuration spools about 500rpms faster! You can upgrade to the .70 a/r BEP t3 turbine housing and have the same or slightly faster spool speed as the above gt35r with ALOT more flow per psi and consequently more horsepower per psi. This makes for VERY good pumpgas numbers.
•Holset patented map width enhancement. They do not have extended tip technology, but there compressors show more efficiency than their garrett or mitsubishi counterpart.
•They have superback technology witch leads to VERY, VERY durable compressors. The are designed to be overworked and underpaid.
•There are discrepancies all over the web concerning the compressor maps. Take what you hear/read with a grain of salt and a shot of tequila, and the worm.
•The holset is fine with stock 4g63 oil pressure from the oil filter housing. If you have no b shafts, you'll need a restrictor. The drain line is a garret bolt pattern. The feed line is different for different turbos
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At this point I am going to drive for a few more weeks and look for tell tale signs of leaks on the exhaust side around the adapter.