Just bought a school bus with a 1990 5.9 cummins. Not looking to hot rod it, but it is too big of a dog as is. The bus will serve as a tailgate/roadtrip vehicle. I am completely new to diesels but have already found myself facinated. I have been reading up and plan on the following:

1. Install a pyrometer
2. 3200 rpm Govenor Spring
3. Grinding the fuel pin
4. Adjustng the star wheel, full power adjustment, and smoke screw

Right now the turbo is a non-wastegated H1C with a 21cm turbine housing. This thing spools like a dog. Right now I have a HX35W sitting in my shop that needs rebuilt. I was thinking of either putting the HX35 on there or buying a 16 or 18 cm housing for the H1C. Now for my questions. I am leaning towards putting a smaller housing on the H1C. Would there be any problem with this turbo not having a wastegate? What to you see as the best option? Please feel free to throw any advice/suggestions/flaming my way. Thanks

 

I would first get gauges, than start turnin up the pump, everyone says the 3200 spring is excellent, i have one just havent put it in yet. i would put the hx35w on for sure. the smaller exhaust housing will fix your spool up problem. hope this helps

 

I know the HX35 would definitely spool fast, I was just thinking that the 12cm turbine on the HX35 would be too small and might shoot my EGT's through the roof. This is a full size 66 passenger bus that will also be hauling a trailer full of motorcycles on roadtrips. That's why I was leaning towards sticking with the H1C and going with a 16cm housing.

 

Well if EGT's get hot put 4'' exhaust on it. that will drop temps and make more power. If EGT's are through the roof than do water meth.

 

But the HX35 flows more air than a H1C, volume wise per psi of boost. If you go with the H1C, get a 16cm and a HTT or GDS stage III compressor upgrade. Install the gauges as the bus might be making full potential as it is heavy and the EGT's are probably around 1000* already. Be carefull.

 

I think your plan looks good, though I'd make sure the fuel pin is at it's deepest position and drive it a bit like that before grinding on it. A heavily ground fuel pin can drive EGT's up. Is the bus an auto or stick? If an auto, alot of guys go with the 16 or 18.5 housing because it only needs to spool once. On a stick, maybe a 12, but with the heavy vehicle it might be restrictive at highway speeds driving up EGT's again. Most guys would say that a 16 is a good compromise between flow and spool. In any case, a better cold side will help both boost and air flow, keeping EGTs in check.

The gov. spring and adjustments will go a long way, do those first and see how you like it before throwing down the cash for hard parts.

 

x2

only part I would buy is the GDS-CH-05 http://www.gdsdieselparts.com/all_years_dodge.htm and stick that on the 18.5 or 16

the 12housing I wouldnt even think about

 

I'm with Bob. In the highway this thing will be wound up and working hard, you need a big housing. See if you can pick up a used 18.5, that would be ideal.

Keep the AFC adjustments conservative, it is easy to melt a hard working engine that gets too much fuel before the boost comes on. Settle for some lag to keep the EGT down. Also don't throw a lot of timing at it, that will kill a hard working motor.

The setups a lot of us have work fine in a pickup that hardly if ever has to knuckle down and pull hard, but they are far too radical for a bus/medium duty truck application. Concentrate on getting lots of airflow and adjust the fuel for reasonable EGT (1200 degrees max at the end of a WOT 0-60 run).

I don't think you'll need a wastegate. With reasonable EGT you will be hard pressed to exceed 35 psi running an 18.5 cm turbine housing.

 

All I gotta say is why isnt my road trippin, lake loungin, mountian maneuverin school bus Cummins powered. I had to settle for a 366 big block. Im lovin' what your doin' here.
Being a fleet mechanic for a school district for a while I do know that turning a VE or P7100 up only made em get hotter MUCH quicker. It was fun for about 30 minutes, but the heat would slowly kill em. Your going to be a little limited and what you can do because of how hard its working to just move itself down the road.
Little bit of fuel, some better air flow and I think youll be happy...........Its a school bus after all.
I just want enough power out of mine to haul some old couches, some buddies and a "cooler" or 7

 

Yeah, a real coolant temp gauge is a good idea. You don't want to see it running over 210. You can score a cylinder even without high EGT when it's running hot.

The coolant distribution housing that replaces the rear freeze plug could be a good investment if it will clear the bellhousing adapter in this application. It increases coolant flow around the back two cylinders - which are usually the ones that get scuffed.

 

Thanks for all the replies! That's what I was thinking, I thought the 12cm would be just a little to small for this bus. So now where is the best way to find a different housing besides ebay? Where can I read more about this coolant distribution housing? Thanks again for the help and I'll be sure to keep the progress posted. I also plan on a 4" downpipe to a 5" stack off the side of the bus.

 

The classifieds here and at TDR should be able to provide you with a used turbine housing.

Info on the cooling kit:
http://www.puredieselpower.com/catal...er-p-1374.html

 

Does the cummins cooling kit only work on the 2nd gen 12 valve or can they work on our 1st gen?

 

So I don't think that the question was ever answered...

Is the bus 5 speed or auto?

What about the HX-40. I everyone hates it and says it's crap and all... but if you are nice to it there is no reason that it won't last. Then he would have a true 4 inch outlet. I think like we said, keeping things cool are a big concern. Since the bus is a 90 I would assume that the motor is currently non-ic. He shoulo have plenty of room up there to put in a 1st, 2nd, 3rd, or maybe even and OTR truck intercooler, lol.

I say open that thing up (airflow wise) BHAF, turbo with a true 4" outlet, and a 4 inch exhaust. Let that motor breathe first... then start looking at adding fuel.

 

Keep in mind that the bus probably weighs 16,000 pounds on its own, so if you're pulling 20,000+ on the highway for long periods of time that could do really bad things to the engine if it isn't adjusted properly. The 2000 model International bus I drive does 65mph on a flat surface at wide open throttle, and it takes a really long time to get there... and that's empty and not towing anything. I think that's at about 2800rpm too.