Anyone tried 35/40 with 60mm wheel and a 12 WG housing??

[Hohn]

I'm considering having HTT upgrade the cold side of my turbo using a 60mm wheel. This would give me an HX40 compressor mated to my oem 35 turbine side with the 12 housing (it's cheaper than buying a new 14wg to go with it).

Now, my gut tells me that the 12 hsg is too small even with the stock 35 compressor, and putting on the 40 wheel will only make things worse.

Then I get to thinking that this might not be the case. Follow me, here.

First, I live in altitude. Spoolup is the SINGLE most important factor to driveability, low smoke, and fun. This points towards a smaller housing.

The thin air of higher altitude makes the job of a smaller 56mm wheel tougher. The little wheel has to spin faster to make X amount of boost, and this pushes it off its efficiency map much sooner. For example, the 60mm wheel should have much lower discharge temps @ 30psi boost than would the 56mm wheel, especially in high altitude!

But there are drawbacks, here.

1) the heavier 60mm wheel MUST spool slower than the 56mm 35 wheel.
2) If the turbine housing is on the small side for the 35 compressor (and it is, due to emissions), then the mismatch would seem to be even worse pairing the tightest 35 housing with a 40 compressor.


Holset's smallest housing for the Full HX40 is 16cm. There's probably a reason for that. Keep in mind that this is also paired with the 40s larger (and failure-prone) turbine wheel, so the 16cm turbine section of an HX40 flows a LOT more than would a 16cm housing would on a 35's turbine, because the wheel is so small.

So here's what I would expect from a 35/40 with my 12 hsg:
1) slightly slower spoolup
2) Lower boost@ cruise, w/ higher EGT on average
3) Slightly lower WOT EGT for a given boost. IOW, at 35psi, the big wheel is moving more air.


I'd like to upgrade my turbo, but I'm afraid of taking a step backwards. Why? Well, slower spoolup is one thing, but I also think EGT may get higher because of the tight housing and small overall turbine section. It stands to reason that the 60mm wheel would take more turbine hp to drive, increasing drive pressure. This higher drive pressure may only make EGT worse on the top end.

So, if a stock 35 can get CRAZY high drive pressure once you get to the outer limits, would a 40's larger compressor wheel make it better or worse? I don't want 50psi drive at 30psi boost.

Please help me out if you have experience with this upgrade (or a Dodgezilla).

jh
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[Fishin Guide]

I am unsure what PDR uses in thier PDR 35, but I run it with a 12cm housing.



Top end clearly suffers and all the fuel cannot be used. However, it spools right now and runs clean down the road.



The reason the exhaust side is so big on the HX40 is because of the engine that it was made for. More displacement than out applications and it needs the exhaust flow.



Dave

 

[vssman]

I've been running a HTT stage 3 with a 12 housing for a couple of years. EGTs are in check (were in check prior to the 4gsk). Lag?? What's that?

Max boost set to 44-46psi.

 

[Dual EE]

Here is a thread on the DZ w/a wg 12cm housing.



https://www.turbodieselregister.com/forums/showthread.php?t=143377

 

[Hohn]

I am unsure what PDR uses in thier PDR 35, but I run it with a 12cm housing.

Top end clearly suffers and all the fuel cannot be used. However, it spools right now and runs clean down the road.

The reason the exhaust side is so big on the HX40 is because of the engine that it was made for. More displacement than out applications and it needs the exhaust flow.

Dave

Pretty sure the PDR35 uses a 58mm comp wheel.

 

[jwilliams3]

Should help out your EGT's a bit and up power, even if you are keeping your 12cm2 housing.

 

[Forrest]

Now, my gut tells me that the 12 hsg is too small even with the stock 35 compressor, and putting on the 40 wheel will only make things worse.



jh

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re: the 12 housing, there was a writeup in an old TDR issue comparing the WG 12 to the WG 14. It went something like @ 30 or 32psi, the WG 12 presented > 70 something psi of backpressure, as where the 14 was 60% less.



That being said, you might want to get one of the more efficient 12 housing'd hybrids instead of investing just on the compressor side.

 

[Hohn]

OK, that's with the 35 comp side, no doubt.

So, does the bigger cold side make the dp balance better or worse???

 

[PC12Driver]

Keep in mind that once the wastegate opens and boost stops climbing, so does the drive pressure. Especially with your modded-to-work-on-all-six wastegate. I don't think drive pressures are anything you need to worry about. Especially with only a 2cm difference.



Ever notice that most folks with drive pressure issues are running a turbo way out the top of the compressor's efficincy range, usually with the wastegate disabled? A slightly smaller exhaust housing isn't the problem. Keep yours wg'd below 36-ish psi and I'd bet you'd still be really close to 1:1.



I really liked my DZ with a 12cm for daily driving. A nice combo of spoolup and midrange boost. I didn't play with the top end much since my wastegate was disabled (my 12cm was for a compressor mounted wastegate actuator which won't work on the DZ). And that was with a 62mm wheel.

 

[Cooker]

Keep yours wg'd below 36-ish psi and I'd bet you'd still be really close to 1:1.

This is not the case with a stock HX35. Typically at 30 psi of boost it is making 40-45psi of drive.



I agree that a good WG and keeping the turbo running on it's map is certainly a good way to help keep drive pressures in check. Maybe with a big external WG you could run 1:1 on an HX35 at 30 psi of boost?

 

[rockjeep73]

This is not the case with a stock HX35. Typically at 30 psi of boost it is making 40-45psi of drive.



I agree that a good WG and keeping the turbo running on it's map is certainly a good way to help keep drive pressures in check. Maybe with a big external WG you could run 1:1 on an HX35 at 30 psi of boost?

I dont see the need for a big external wastegate in order to keep the drive pressure down, wouldnt the modified internal wastegate be able to do the same thing in order to get the drive pressure to 1:1.

 

[Fishin Guide]

Cooker, I do not know. But, with a modded wastegate on my buddies truck, anything over 28 boost resulted in 30+ drive. Switched to a hybrid 35/ 40 and it had a clipped wheel with a 14cm wastegated housing.



Boost vs drive were pretty stable up to 36 psi boost. After that, drive pressure went nuts. And the temps started to really soar!!



There are so few pieces of technical data available on boost vs drive that most folks don't have a clue. Every truck is a little different. That 1:1 is a tough cookie sometimes. That's why compunds are so attractive. Well, that's if they are matched.



Dave

 

[Fishin Guide]

I dont see the need for a big external wastegate in order to keep the drive pressure down, wouldnt the modified internal wastegate be able to do the same thing in order to get the drive pressure to 1:1.

Yes, if you are not runniong too much fuel. If the wastegate can't get rid of enough drive pressure, then you "blow past the gate".



I think for most mild trucks, that's not too much of an issue.



No, I'm not talkin about an 800 HP monster! :-laf



Dave

 

[swankmetal]

hohn, at 40 psi with my h1c/12cm i had 75 psi dp. when i switched to the 60mm wheel it dropped to 48 psi. bigger wheel=less work for the turbo (as far as i can figure). i'm between 5000 and 6000 ft everyday, too.



dave

 

[zstroken]

I think the 24V have a 54 mm compressor wheel don't they? The 12V hx35's had the 56mm. THis is from memory so I could be wrong.

 

[PC12Driver]

This is not the case with a stock HX35. Typically at 30 psi of boost it is making 40-45psi of drive.

Sorry I wasn't clear. I was referring to the Hybrid version with the 40mm wheel.

 

[Cooker]

Now that I think about it I have read the Dodgezilla's (1:1 almost all the way to 40 psi) have very reasonable drive pressure readings as compared to a stocker. I guess the OEM gate on the turbine housing can aid in controlling DP as long as the truck is not too overfueled.

 

[Hohn]

I think the 24V have a 54 mm compressor wheel don't they? The 12V hx35's had the 56mm. THis is from memory so I could be wrong.

I thought it was the other way around-- because the newer trucks came from the factory with more HP.

 

[rockjeep73]

I think the 24V have a 54 mm compressor wheel don't they? The 12V hx35's had the 56mm. THis is from memory so I could be wrong.

California trucks have the 54mm wheel, all others should be 56mm.

 

[jwilliams3]

zstroken is right if I remember correctly.