3rd Gen Turbo Swap Write Up

Big Blue24

Big Blue24

Comp Diesel Sponsor
Joined
Jan 5, 2008
Messages
6,320
Well, Smokem and some other members have sent me PM's asking about my 3rd gen turbo mounted on my 99' 2nd gen.


Turbo Specs:
Stock 99' HX35= 54/78 mm compressor, 58mm exhaust turbine, 12 cm exhaust

04.5-07 HE351= 60/88 mm compressor, 60mm exhaust turbine, 9 cm exhaust

Pre 04.5 turbos are small like the HX35, so I bought a 04.5+ HE351cw turbo off ebay, used $245 shipped to my door.

I immediately went to town with my dremel tool to open up the wastegate passage because this turbo comes with a smaller 9cm exhaust housing=fast spool but limited topend flow. I opened up the wastegate passage to approximately 27mm, large enough to easily pass a quarter through the whole passage.

I then ordered a 180* mandrel bend 3" aluminized bend. One 90* & one 45* 3in silicone coupler, a 2.75" to 3" silicone reducer, and t clamps for all the connections.

Because the wastegate head mounts on the compressor of the HE351 turbo, you cannot independently clock the exhaust housing and compressor housing. So, I basically reclocked the center section to allow the oil drain to face straight down and line up properly and the compressor outlet=coldpipe, came out facing around 11 o' clock.

Here's some pictures to help all visualize the setup. Note, that is a standard K&N intake setup, tilted slightly and shortened about 3/4" on the turbo end.
 
Last edited:
And some more pics of the intake tract.

When I did the swap, I wanted to retain the ability to go back to stock if this didn't work so I did the conversion in such a way that I could easily go back to stock. As you can see in the pictures, it took a couple of extra bends to get the cold piping all connected, but surprisingly, I have had zero issues with boost leaks or boots blowing off, even at 44 psi boost measured at the intake manifold.
 
Last edited:
Looks awesome. I have been eying those turbos- my big question is how do you get the VNT (Or VGT, if it's like my Jetta's turbo) to actuate without the 3rd gen computer? I am curious as to whether or not it would be an improvement in spool-up time. I'm putting a 12V in my 1994 Ford and am still trying to figure out a turbo setup. Using a regular old HX35 seems too boring, and I'd like a little more than 400HP.
 
For starters, the VGT turbos are coded HE351ve and they came on the 6.7 liter cummins in late 07'

This is a HE351cw, 04.5-early 07'. The black electric solenoid is really just a fancy bleeder valve. When the ecm sends a pulse width modified signal, it opens a neoprene washer to vent boost pressure out of the silicone hose.

Under normal operating conditions, the wastegate on this turbo acts like any other turbo. It always has pressure from the charged air side of the turbo. This pressurized air is fed through the "blue in these pics" silicone hose to the wastegate head. When the head gets about 23 psi boost, it starts to move and it fully opens around 27 psi.

*Key* there is a small hole that feeds air into this system, so only a limited amount of pressurized air can come into the blue silicone hose system. When the black solenoid opens, it creates a vent 2-3x larger than the small feeder hole so basically 0 pressure can go to the wastegate head to make it open.

On a stock 3rd gen, the ecm allows spikes of boost, upwards of 32 psi. When the engine wants to allow boost to rise above 26 psi, it sends PWM electrical signal to the solenoid and causes it to vent the blue hose's pressure so the wastegate becomes in operable for as long as the signal is present.

In my application, I simply left the solenoid alone, it is air tight when it has no electricity and it does not inhibit the flow of pressurized air to the wastegate head. Rather than tap a new boost source or weld a bung for a boost elbow, I just left the stock setup stock, but, I purchased a cheap ball and spring boost controller that I plumbed inline.

The way my controller works is that is a brass tee with an inlet, an outlet, and a bolt on the third opening. The bolt pushes on a spring that pushes on a ball bearing that plugs the inlet to the tee controller. The more you screw in the bolt, the more it compresses the spring and the more force/better seal the ball makes to prevent incoming boosted air. With this adjuster, I can control the amount of pressure that makes it to the wastegate head. I can effectively force boost to rise to say 40 psi, before any air goes through the controller to push on the wastegate head.

http://cgi.ebay.com/ebaymotors/NXS-MANUAL-BOOST-CONTROLLER-GSX-240SX-300ZX-TURBO-WRX_W0QQcmdZViewItemQQcategoryZ33742QQihZ015QQitemZ250236020181QQrdZ1QQsspagenameZWDVW
 
I emailed Holset, through Cummins a couple of months ago. They wouldn't give me a compressor map, but they did tell me that the HE351cw, my turbo, would flow 67 lbs of air per minute corrected to Garrett's standards for temp, atmospheric pressure etc.

After doing some rough numbers using Garrett's HP/ Airflow calcs, I figure that this compressor is capable of 475-500 HP. This theory is also backed up by multiple 3rd gens in 500+ HP range with ludicrous egts, and high 45-50 psi boost on this stock to them turbo.

The downside is the restrictive 9 cm exhaust housing. The turbine wheel is about 2mm larger than the HX 35's so it should flow a good bit more exhaust. I also opened up my wastegate to nearly 27mm, and it definitely does it's job and totally prevents boost creep.

EGT's are down about 100 degrees with this turbo. Power is definitely up, and I plan to dyno soon, although I don't really have a baseline to compare HP #'s with. Turbo timer cool down time is longer, this housing definitely takes longer to cool down after a hard run.

If I had to guess, 50 HP increase would be my answer. The whole project cost less than $500 and after accounting for the sale of my HX and old downpipe, I'm into the whole ordeal about $150 bucks.

I did utilize the stock 05' cast 4" elbow so a third gen exhaust brake would be really easy to add.

A DTR member gave me a 3rd gen down pipe of which I was able to utilize 12" and with the addition of some 4" flex from the big rig store, got my exhaust all buttoned up. I had a pre existing MBRP 4" system so the exhaust wasn't too bad.
 
Spool is the only thing that I have not addressed. Lets put it this way, I have positive manifold pressure at idle. Spool feels nearly identical but slightly slower the first 1/2 second you hammer it. But it definitely hits harder than the HX35 ever did, and will spin the tires in 3rd when the turbo lights, whereas the HX would only chirp a bit on dry road. Where I really noticed this turbo is at highway speeds. At 65MPH, the HX doesn't have much punch when you floor it. The HE pulls much harder at 65MPH when you floor it.

Final benefit, I was able to retain the silencer ring! This is a big bonus for me since my wife couldn't handle the HX without a silencer ring.

I guess all that I need to do/prove to get others to try is some dyno numbers to show the hp and huge torque increase. This is one of my few mods that really increased driveability.
 
I appreciate thinking out of the box but I doubt your gonna make 500hp with that turbo. It's to bad you didn't have a baseline with the hx35. It would have been interesting to see the difference.
 
Lets put it this way, I have positive manifold pressure at idle.
Click to expand...

How can that be????
Positive manifold pressure,or boost,at an idle is a sign of other issues.I'd love to see what the drive pressures in the exhaust housing are I'd bet money with you seeing positive pressure your exhaust pressures are more than double.
 
Yeah, it's less than 1 psi, somewhere around .25-.5 psi. Turbo does spool quick though, alot like the stock HX35.
 
Nice write up....Ive got a coupe of friends that are considering this and ive forwarded this thread to them.

Thanks
 
Tyler dont be mad that he is going to break 500 before you on a stock turbo. LOL
 
I believe it has a 12cm housing like a hx35. A 03-04.4 turbo...he341 has the 9cm housing, when the went to the 351 back to a 12cm housing.
 
haloman said:
Tyler dont be mad that he is going to break 500 before you on a stock turbo. LOL
Click to expand...

I might be alone in left field on this one, but my money says Tyler's truck will make more power than this setup unless nitromethane is used as an additive again.
 
I think BigBL's truck makes more power too. I think it is just cursed when it comes to the dyno and sandbags.

FYI there is no such thing as a 12 cm housing for the HE351, HE341, or HY9, they all came with a 9cm housing. Ind Inj, makes a "stealth kit" turbo with a bigger housing, but it also features a larger turbine wheel so it is a no go. It's also out of my budget $ price range.

When I dyno, I do believe I will have more HP per dollar than a lot of trucks out there. I don't plan on much more for old Blue, it has 232K hard miles and will be traded or sold to make room for the "awesome" common rail.

While we are on this topic, where in central/northern Utah is a reputable dyno shop? I think Zane Koch is nearby but probably wouldn't let a cummins anywhere near his shop or fancy dragster. Too bad II, or HTT, or Edge doesn't have a nearby dyno. I saw Maddog's dyno once but the torque pickup wasn't working so I passed on the $75 hp sheet.

I'm moving to Las Vegas in a month, any reputable dynos down there? If I magically make some HP, I don't want crap because it was a 232 wimpy dynojet or something.
 
You must log in or register to reply here.
Back
Top