whazzup

I have read on this and several other forums that the 35 and 351 share many of the same parts. I have a 06 351a nice turbo for every day stuff but warm for towing, does not cool as well as i had hoped. Now my question, will the 351 comp wheel and cover fit a 35?

gorms

Well I'm not sure if you could make a 351/35 hybrid...but I don't know why you would either? 351 has a larger shaft and is less prone to snapping when "barking" or overboosting. Are you running a 351VE ? Those are variable geometry and need some finicking to get the vanes to work at the right time....

A 351CW from an 04.5-07 is a traditional wastegated turbo, 60mm compressor, and although it has a small exhaust housing (9ccm) it has a large wastegate and works nice for stock-ish injectors.

What pressures are you running on the 351 you have now?

whazzup

It is a CW, i have no idea on drive pressure, boost at WOT is max 33 LBS. The turbo spools very well but the old HX-35 does a much better job with the TT in tow. I was under the impreesion that a rebuild kit for the HX and HE were the same, is that not correct?

gorms

Any wastegate? That turbo will choke in higher RPMs (much over 2k) without opening the gate. Same with the HX35, it just has a little more room with a 12ccm exhaust housing...

Maybe you're thinking of HX40 and HX35, I am pretty sure they are close to each other, same cartridge/journals etc.

whazzup

Yes the gate is set to open at 30 LBS. I did not open up the passage. I live at 6000 FT elevation and it only goes up from where i am at, when i go to Phoenix it is a different animal the HE works great. OH well i will just go back to the HX and sell the HE.

BILTIT

I know for a fact the he351cw uses a hy35 rebuild kit (put one in myself). Is the hy35 the same as a hx35?

gorms

Ah 6k ft is a different animal. I'd be thinking about twins or water/meth at those altitudes. I would still think the 351 would be better at altitude though.

whazzup

The initial spool is better but it gets alot hotter alot faster than the HX. I was looking for a more better animal at higher elevations. So far the he has proven that it lacks a bit, at least for me. When you say it chokes above 2k RPM how do the third gens run them? Every late model I've driven seems to enjoy spinning higher revs than my lowly 12 valve. Do the third gens run that much warmer?

BILTIT

3rd gens have better flowing heads and more efficient injection. They do run warm too. I run my 351 to 40psi, maybe you need to up the boost?

whazzup

I thought about pushing it harder but was worried about the drive pressure being to much with the 12 valve head not flowing as well.

BILTIT

I run 40psi with the wastegate wired shut, i shouldn't as my drive pressures probably spike. As long as you have a working wastegate you should be fine with drive pressures.

whazzup

Well Holset changed enough on the turbo to where parts wont interchange without some work. The center section innards are the same but the physical dimensions are different. So in order for me to put the HE 351 comp. wheel and cover on my HX I need a machine shop to open up the HE cover. Or would one of the many members here have a HX-35 60mm comp cover they would get rid of?

cougar

No, there are several difference. Not much published data from Holset on them. But, if you set the 2 side by side the difference become obvious. The HY is smaller than the HX. Besides the turbine housing, the compressor side is also different. The HY has a smaller compressor. The waste gate actuator is set up different as well. Performance wise, I couldn't tell you as I have not been able to drive my 01 much from day one because of mechanical problems. The turbo being one of them.

whazzup

OK i can understand that the third gen heads flow better, but on the 12 valve is the head the choke point or the 351 i am trying? It was mentioned that the 351 chokes up over 2k, is that true for all head designs? I was thinking that the turbo should be fine for me, it flows OK for the CR trucks. I very, very rarely run anywhere close to 2500 RPM with the truck, towing I am between 1800 to 2200, much under 1800 EGTS skyrocket and much over 2200 the same thing happens.

Just for fun I put the HX back on and installed a drive pressure guage. The HX has the divider drilled a HX 40 style outlet and the turbo exhaust inlet has been ported out to match the gasket. I have backed the plate off to where i have 32 pounds boost at WOT. (With the same fuel the 351 was doing 35 pounds of boost) Drive pressure up to 23 to 25 pounds of boost is pretty much a 1 to 1 thing. Once it hits 32 pounds boost, drive pressure is 48 pounds, i was kind of suprised to see that.

Here next week I will put the 351 back on and run around with it just to see what the difference is.

How does elevation and density alltitude affect those numbers? I live at 6k and all this week with the temps here, density altitude has been anywhere from 7800 to 8600 feet.