Looking into turbo choices and the Holset HX-40 seems more and more appealing. Internal wastegate option, and affordable to buy and rebuild. However, I see that some of them are in an oil-cooled only configuration. I don't doubt that thought was put into that choice by Holset, given that they are designed for pickup trucks that spend extended periods in boost, but still I thought it to be a strange choice. After doing some research, I found this thread here: Link

The data there is useful in that it indicates water cooling provides a measurable benefit in terms of heat dissipation, but that doesn't tell me anything about how directly it affects longevity (obviously longevity decreases without water cooling, but how much longevity is lost on average is unknown).

Turbochargers are basically a wear item, especially given how hard rotary engines drive them. That being said, longevity is still an obvious concern. What are people's experiences with and opinions about oil-cooled turbos? How long did yours last before requiring a rebuild? Anecdotal evidence is great too, but I'm curious to see the feedback from people who have personally tried them (and info from someone who has tried an oil-cooled HX-40 would be especially useful). Thanks.

- Chris.

 

Other than the borg warner efrs nearly and mid or large frame turbo with an internal wastegate won't allow decent boost control for what most people want on pump fuel.

 

Sounds good, I'll start looking into external WG setups. Thanks

 

Also interested to hear experiences with oil cooled turbos...

 

They're fine as long as you allow your oil to cool to prevent 'coking'. Personally I think that the only reason why turbo timers were a fad for so long was because a bunch of 80's diesel cars were oil cooled and gas engined fanboys jumped on it as a toy to bolt on even though they were run oil/water cooled turbos.

As an example during our dyno testing of an EFR 9180 we only oil cooled it, we also had a 5 gallon dry sump though so our oil temps were pretty chilly by comparison.

 

I have a Holset HX-40 (oil cooled only) on my FC, it was machined into an s5 turbine. I got the 12 blade OEM inconel exhaust turbine wheel (65mm i think mabye 67) and the standard 60mm compressor wheel, i see 14-15 psi at 3500-4000 and it only creeps to 16psi at 6700. I have ported the s5 wastegates.