Big Blue24

I just got an email from Holset through Cummins. All that I can say is you better think twice about upgrading your 04.5-07 turbo, it flows 67 lbs/min.

Here is the email:

"Good Afternoon,

Thank you for your enquiry,

I have spoken with our technical team and they have advised me that the HE351CW will supply a maximum of around 67 lb/min corrected to Garrett mass flow parameter.
This occurs at a speed of 130 krpm which we do not recommend to exceed (same applies to the HX35).

Kind Regards

Nikita Toulcher
Cummins Turbo Technologies Ltd"


Well, if you do some research, and math, you find that the BD Super B flows 61 lbs/min. I am not ripping on BD, their little turbos are tough, come with bigger wastegate etc, but a stock 04.5-present 5.9 HE351cw is a great turbo!

jrussell

They are definitely great turbos for their size. They'll cool 450hp at 40psi with no problem!

They even work great when used in a twins setup!

chrleb1

the 04.5+ turbo is good, but the exhaust pinwheel is too small.

J-man

So, can you get a decent twin setup fairly cheap if you stack with the stocker?

homewrecker

Yes you can.Do a search for twins stock/s480, or just call Nathan Wright at MPI(maximizedperformanceinc.com)

jrussell

Yep, and the best part is that it's easily upgradeable if you outgrow them!

Nathan is the man when it comes to twins.

Big Blue24

If you enlarge the wastegate like I did, you can bypass enough flow to give some more top end performance. I am still testing, and fighting a little fuel in the oil to give conclusive results but so far, I like this turbo! My wastegate works so well that when I throw 500 HP worth of fuel at it, I don't get any boost creep. Amazing what a 27mm internal gate can flow!

w.tx iceman

Is it possible to change exhaust housings like the 2nd gen

N.Johnson

Hey that's great you actually got a reply from Cummins on flow numbers, very cool. Here's some more numbers from a issue of TDR. The stock turbo 9 cm housing is about the same size as a 1.3" ID pipe. Talk about restriction.... and here I/we are all worried about exhaust/intake restrictions. The biggest choke point on the truck is the stock turbo exhaust housing. Imagine what the drive pressures are like on a stock turbo pushing 500 hp

Checkmate

So if I am reading correctly here. The 04.5 turbo is better than the 03 turbo ? If so, is it a big enough difference to warrant a change ?

Big Blue24

I think that it is definitely worth the hassle on my truck. I think it would be a no brainer for someone who already has the correct plumbing. Your stock turbo at best has a 56mm compressor.

The only drawback as previously stated is the small 9 cm exhaust housing. You are already running a 9 cm housing. If you buy a newer turbo, be sure to port it out a little before you install it.

Checkmate

So with this turbo I would be able to run higher boost and still run cool ? I am very interested in this since my engine is currently out so this would be NO extra work for me. I would try and find one at a bone yard if possible.

Big Blue24

It would help alot, but remember that it is pretty restrictive on the exhaust side so any port matching, wastegate opening up you could do will greatly benefit this turbo.

Just because the compressor can push 67 lbs per minute does not mean the exhaust turbine wheel can handle 80 lbs per minute. But a larger wastegate can. I opened mine up from the stock 22mm to 27mm. Any larger and I was afraid the wastegate puck would not seal. 22-27 = 33% increase in wastegate flow.

I have only ran my turbo up to about 30 psi boost, I am still getting everything tuned, but I can already tell that it has more capacity than my HX did.

jrussell

The stock turbine housing looks quite a bit bigger than 1.3" ID. Even if you upgrade to a turbo with a larger exhaust housing, it's still going to be the biggest restriction in the system. That's just the nature of turbos. Restriction = boost.

SandRam

To piggy back this question, what changed from the '03 (305/555) turbo to the 04.5+ turbo?