holset hx35w

[MVDyken]

Just to let any body whose intrested in the Cummins Holset HX35w turbo conversion. I just got done installing it and can say that I am very pleased with the outcome. I am running without and intercooler as for now and will soon have one installed and also the motor still has stock compression too:(
The boost starts to build and 1300 rpms and pulls strong all the way up 15-16psi cruising at 70mph boost is about 7-8psi this turbo make way more power than the stock gm4 that I had on. The only problem that was incountered on the install was the exhaust it was so tight that a 90 degree right angle had to be used and kind of made egts higher every thing else bolted right up. be back soon with more results with the intercooler

[john8662]

Good deal, I think you made a wise move, the HX and HY series make a pretty good transition onto the 6.5. THe HY series is a little more restritive in the upper RPM bands like the GM-X series is.

Do you feel that the "spool-up" on this turbo is as good or better than the original turbo was (when it was working correctly).

Watch your boost, don't run any boost above 12psi w/o an intercooler, especially on a 21:1 C/R engine.

J

[dieseldummy]

I wouldn't run anymore boost than you are even intercooled with stock compression. That's experience speaking... The blocks flat out don't like it. I've been running the HY35 for over 1 yr now and a WH1C before that. I think you'll like it for a good all around turbo.

[MVDyken]

Yes, I do think that this hx turbo builds boost about 500-750 rpms sooner than the best days that I have had the the stock GM-4 Turbo. And I don't like running any more than 10 psi with out and IC but the turbo doesn't stay below 15psi. Hate to say it but this HX 35 works almost to good! I am going to put 2 IC in to help lower psi so that when I smash the throttle the boost doesn't go beyond 15.

[DA BIG ONE]

Just to let any body whose intrested in the Cummins Holset HX35w turbo conversion. I just got done installing it and can say that I am very pleased with the outcome.

Is this an easy conversion, or?

[MVDyken]

My conversoin was not to easy, the 4 bolt that hold the turbo to the headers were prety much welded to the header. So I had to take the down pipe, x pipe, header and a front tire off, that was just to get the turbo out. then I installed HI pop injectors too. And I had to torch the bolts to get the turbo off and 2 bolts the x pipe off. But if you can get the turbo off this conversion would probably take only 2-3 hrs to complete plus time to make exhaust line up from the down pipe. The back of the turbo and the down pipe are right on top of each other, So I had to cut miter cut two 45's to make 90Degree right angle exhaust piece and if you have a old down pipe to get the V Flange off of that will make it even easier. Then I didn't like haveing that sharp of a bend so I fabricated a little piece of metal that was bend to about 90 degrees and welded that in the exhaust piece to make it more smooth I Will try to get son pic's soon

[ronniejoe]

According to my turbo matching calculations, the HX35 is a very good match for the GM 6.5 if you are looking for good performance improvement. However, be careful of running too high boost at low rpm. The 1800 rpm operating line crosses the surge line at about pressure ratio 2.6:1 and the 1500 rpm line crosses at about 2:1 pressure ratio at sea level. The HX35 should be able to run 15 psi up to 3500 rpm and 11,000 ft above sea level.

For those wanting more...stay tuned!

[DA BIG ONE]

Think the 40 would be better to stay out of surge line, or?

[john8662]

If I can find a *40, that's what I want to try, but this isn't on the daily driver neither...

[dieseldummy]

Those flow charts only tell part of the story RJ... half of it actually. The exhaust side always has to be added to the equation.

[ronniejoe]

Precisely.;)

[Patrick m.]

is it restrictive up top, like the GM-x series?

[ronniejoe]

I was headed that way, but havn't run the HX35 yet. I've decided that I need more than it can produce for me. I will likely eventually test one. For most folks, the HX35 will be a really nice upgrade. There are several options for the turbine housing, so some dialing in may be necessary.

I will be mounting up and testing something else in the next week or so. My calculations say this will be a winner. We will see when the rubber meets the road.

[dieseldummy]

I always thought that a hx35 w/the hx40 compressor housing and wheel would be a good combo for a heavily fueled 6.5. Good spoolup and massive flow. I almost bought one once, the $800 price tag scared me off...

[DA BIG ONE]

I'm thinking more cfm @ lower boost so the 6.5 will stay together. But I'm not the expert here so I wait!

[MJEasly]

I'm thinking more cfm @ lower boost so the 6.5 will stay together. But I'm not the expert here so I wait!

I'm thinking the same thing - better exhaust flow through the turbine with the benefit of compressor efficiency (less intake charge heating) at stock to moderate boost levels.

[ronniejoe]

You are exactly right on the efficiency thought, but not on the "more CFM with less boost" thought. I plan to write an article on this whole subject of compressor matching to help explain this to folks.

Breifly... If engine speed increases but turbocharger speed doesn't, then you will move more air with lower boost pressure. This is moving to the right on the map following a turbocharger constant speed line.

If you take turbocharger A and run the engine at 2500 rpm at 10 psi boost and take turbocharger B and run the same engine at 2500 rpm at 10 psi boost, both will move 27.6 lb/min of air at sea level. Period. There may be differences in temperature of the air due to differing efficiencies, but the mass flow rate will be very close between the two.

Now if you could somehow make each turbo rotor spin exactly the same speed as before while increasing engine speed, the boost pressure will drop but the mass flow rate will increase. The two turbos will still be flowing equal amounts of air, though.

[DA BIG ONE]

If we can keep this one going it would be great, every other diesel has lots of turbo options it's time we find that sweet one, or two for the 6.5 td too.