Holset HE341 with 9cm turbine housing - limit?
 

Hey guys,

I've got a Holset HE351 with the 60mm compressor wheel and the T3 flanged 9cm exhaust housing. I've read a bit and see that most guys are running much larger turbine housings than this. Unfortunately there are no larger turbine housings that bolt up to this particular Holset.

I'm more interested in a responsive car on the street than a huge HP number on the dyno but I would love a setup that is capable of 400rwhp.

I'm assuming the turbine housing will be a "choke point" and will be the limiting factor in the setup's ultimate peak number but at the same time it should help response.

My question is what will the car be like with this turbo on the street and what would be the realistic HP limit with this turbo?

Thanks!

The exhaust size of that turbo is too small for a rotary. It has a 58/65mm turbine and roughly a 0.65 A/R T3 housing. Firstly, you're going to have a hard time finding a nice T3 housing without having one custom made. Besides that, the housing is too small and the turbine is too small. for a GT35-sized compressor.
I ran a HE351VE for a year and wasn't as impressed as I thought I'd be. The small 70/60mm turbine on the 351 and the VGT housing made it more choked up than responsive.

If you're looking for something affordable that's still smaller than what most run, check out a TO4B or Borg Warner S256. Both will do close to 400whp and be responsive.

By comparison, the stock twins combined are about 12cm; and good for about 400rwhp (unmodded). And IIRC, the popular [for us] GT-35's are about 14cm.

So the 9cm Holset, maybe 350hp. As is well known, the rotary doesn't much care for high [exhaust] drive pressure to boost ratios: In my own experience, anything more than about 1.35:1 EMP to boost (or an EMP of about 10# greater than intake manifold pressure) and the rotary goes flat really quick; at least with a rather late closing exhaust port and street ported intakes.

In any event, forget any comparison to the DSM and other communities that can run 2:1 or even 3:1 emp:boost ratios with the Holset and other turbos and make big power. They have intake and exhaust valves clogging their ports that allow them to limit overlap and manage their ridiculous exhaust manifold pressures. Our rotary is quite the opposite and simply will not tolerate such conditions; hence their preference for larger housings. Fortunately, we have the advantage of sharper exhaust pulses that can excite those larger housings and turbines without giving up much else.

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