I got a 91 dodge cummins w/o a intercooler and would like to put one in. I am changing my 21.5 cm housing out first to a 16cm, but while i got everything apart i wondered if i should put on a compressor wheel off a hx35 and make a hybrid H1C/hx35. The question here really is, would putting a wheel on like that be fine w/o the intercooler being on since i would have to find a intercooler later?

i understand that if i don't have a intercooler on my truck, i do have bigger injectors then the 91.5's and up. Would putting on different injectors such as POD's make a big difference since my injectors are bigger anyway? Also is it a good idea to put on bigger injectors due to the fact that the heads on the 91.5's and down were weaker (as i'm told)?

Would i notice quite difference if i turned my pump up with these bigger injectors? Would my EGT rise?



thanks for any help


Jeff

 

I dont think you'll have a problem without the IC if you keep your boost normal, the IC is strongly suggested to help keep inlet temps down.

Depending on where the pump was set origionally, there is alot of power to be had with a turned up pump, Im havent heard about weaker heads on NON-IC vs IC Gen 1 trucks.

But anytime you add fuel & air it makes more heat. Theres alot of variabals to this, such as exhaust system, turbine housing, manifold restiction/efficiency.

 

The older heads used a larger diameter injector tip and were prone to cracking in that area. The smaller injector tip was designed to put mere metal in the head to stop the cracking problem.

If it hasn't cracked yet it probably won't.

POD's are still bigger than your stock injectors. You will need to use copper sleeves (commonly available) to run POD's in your early head.

A more efficient turbo is a good thing whether or not you have an intercooler.

Turning up the pump is more effective on a non IC truck than an intercooled truck assuming they both have stock injectors.

You probably have an 18.5 cm housing, AFAIK all the non-IC trucks ran those. The 16 is not a dramatic improvement over the 18.5, but it is noticable.

 

What is the most easiest way to tell if i have the 18.5 cm housing?
Also with putting a compressor wheel off a HX-35 make my boost go way up from the stock wheel? The thing is here is that i know the HX-35 is made to run a higher pressure to compensate for the pressure drop through the IC, but if i have no IC will it raise my boost to high to go directly in with no IC?



thanks for any help

Jeff

 

The size is cast into the back of the housing, you'll need a mirror and a flashlight unless you're really small and flexible. It will have an 18.5 cast in seperate from any othe numbers. The 21 and 16 also have the size cast in. Smaller housings do not.

I assume when you're talking about the HX-35 wheel you mean the 58 or 60 mm upgrade from HTT? Using a smaller turbine housing with a larger compressor will mean more boost. The WH1C and HX-35 came into use because of the small 12 cm wastgated housing on '94's. An H1C is "off the map" at low RPM and high boost with the small housing. All pre '94 trucks used a larger housing and an H1C.

You will see higher pressure than an intercooled truck, but 35-38 psi is still OK. The "pressure drop" through the intercooler is mainly caused by cooling, it's not due to restriction.

 

Do you think that the best solution here would be to find a WH1C or Hx-35, or go through HTT and get there bigger compressor wheel and put it on the H1C? All i really wont to do is get a turbo that will work good with a intercooler and still leave me some room for PODs. If i took a stock WH1C or a Hx-35 and bolted it right onto my 1991 (after i installed the intercooler) would it work ok? Was the compressor wheel different from 1993 to 1994? i have heard small housing on the H1C can cause turbo surges at low rpm and heavy load (on 5spds). Would the WH1C or HX-35 still cause surging

thanks in advance

Jeff

 

That's what I did. I put a 12 cm housing on my H1C and the flutter (surging) drove me nuts. I got a WH1C off Ebay and slapped it on, works great now.

Short answer is no, HX-35 and WH1C's will not cause surging.

I don't think the compressor wheel changed, but what did change was the compressor housing. Holset cut slots in the compressor housing right by the tips of the compressor blades. These are called map width enhancement slots, they allow more flow at low RPM and high boost which cures the flutter. That's the big difference between a WH1C and an H1C. The difference between a WH1C and an HX-35 is how the compressor attaches to the bearing housing, HX-35's use a snap ring, WH1C/H1C turbos use a clamp. As far as performance they are supposed to be functionally identical.

I just put P.O.D.'s in today, the temps seem OK to me. I'm seeing around 1200 at the top of 4th. The only modification to my WH1C is a TurboMaster wastegate controller that is set for 35 psi.

 

Will i have to shorten my downpipe if i throw a WH1C or a HX-35 turbo on?

thanks

jeff

 

Only if you run a small housing like the 12 or 14 cm. With a 16 cm or larger housing it's a bolt on. I am very happy with my 12 cm.

 

You can't just replace the H1C compressor housing and wheel with an HX35. The H1C is a different style turbocharger. It has a separate bearing housing and seal plate that bolt together, whereas an HX35/HX40 has a 1 piece unit. Also, the H1C uses a T-Bolt style clamp to hold the compressor housing on the seal plate, whereas the HX35/HX40 uses a loaded C-Spring that holds it in place from the backside of the housing to the sealplate.

The way to make an HX35/H1C hybrid is to get an HX35 Compressor wheel and have a machine shop/turbo shop machine out the radius of the H1C compressor housing to fit the HX35 wheel. You'll also need to have them machine out the Seal plate to clear the MAJOR diameter of the HX35 wheel.

All in all...just get an HX35 and save yourself the trouble.

As far as the downpipe goes...I run a stock UNCUT downpipe on my '92. I have an HX35W/16cm2-Wastegated Housing. The Downpipe DOES need to be shortened about 1.5 inches...but I've been driving around a while with it jammed up in there. It's not hurting anything. I'll shorten it when I get some time.

 

Also...there is NO difference in a WH1C and your stock H1C...the "W" only means that it's wastegated.

 

Jeremy- The difference between a WH1C and an H1C (besides the wasted housing) is that a WH1C has MWE slots and a silencer ring like an HX-35 - and it does make a big difference. Also, I believe that exhaust housing you're running is a 12 cm wastegated, not a 16. The numbers cast on the back of the wastegated housings do not directly translate into the housing size, only the non-wasted housings have the size cast in.

 

well...I mean internally. The MWE slots DO make a difference. But there is no change in actual airflow between the two. All parts are the same, except the wastegated housing, and the compressor housing with the MWE slots/ring.

My housing is a 16cm2 wastegated...stamped "16" inside the flange.
I also have a 12cm2 wastegated housing stamped "12" inside the flange.
We found out the hard way how Holset likes to identify their housings!

 

If i just put a 16cm hosuing on the H1C for now i wouldn't have to shorten the downpipe......right?


thanks again

Jeff

 

Correct. It is a bolt-in replacement.