Hello folks,

My newest ride is a 97 Bluebird 24ft short school bus on a Chevy P30 chassis with a 6.5 N/A engine converted into a very comfortable mobile home. She is solid and reliable, I have driven at this point a couple thousand miles up and down the mountains and across the deserts of oregon and have had no problems and only some minor maintenance, new tires, starter, steering gear, oil cooler and lines. Tossed in some firestone rear air bags and it rides great. I've done all the maintenance and conversion myself.

Yesterday I drove it up and down Mt. Hood yet again, from portland to government camp, an elevation gain of about 4000ft on a 95F degree day. It worked perfectly and cool like always but my main grudge is power, this bus is spectacularly gutless.

Max speed up to hood is 30mph in 2nd gear. Coming out of fields, oregon in the alvord desert i had to climb one hill in first gear at about 15mph. The bus cannot accelerate up any incline at all without a shift. the 4L80 (85?) shifts a lot even for dinky slight inclines and headwinds on the highway and it is annoying.

Doing some research it appears Chevy put "fuel miser" engines in these chassis that make 120HP. Recent weighing put the bus at 12K pounds fully stocked. This engine can do more, I'd like to take the most economical steps to get some power. Here's what I'm thinking:

- Fresh bosch injectors, assuming mine are original with 140K miles on them it's time.

- Delete intake resonator and exhaust restriction.

- Turn up the pump, advance the fuel delivery screw 1/8th turn.

- Delete stock fuel filter get new lift pump with decent filter.

That's all the easy stuff, what I'm wondering about is the stuff I'm missing. Here are some open questions:

What's the turbo option? I'm reading that the center mount van turbos have special oil ports into the block that I don't have on my engine. There's little side clearance without modifying the bus body. Remote turbo is intriguing but sounds harder?

The marine 6.5 industry seems to have some cool supercharging going on, but i haven't found any good leads with a price tag. Is that cost prohibitive?

I know i'm going to pretty much always be in the right lane with this thing, but a little more power would be super helpful esp when hill climbing and 120HP is worse than what my 6.2 suburban puts out but in a vehicle 3x heavier. Any advice greatly appreciated!

 

Hello there as far as supercharging goes is the $5400 + price tag worth I would think you could get a nicer more powerful motor home for that kind of money maybe a little more so in my opinion turbocharging is the more affordable approach. I personally would do a remote turbo and set the boost at 10-12 pounds.
Is that P30 electronic injected? Or mechanical injection ?

I believe that your rig may be governed being that it was a school bus at one time but I'm not sure how they would have went about it.

 

It's mechanical injection. Yeah supercharging seems like pie in the sky in my budget. I can find turbo kits for hmmwv's on ebay and other sites, just not sure if they bolt right up to the 6.5 N/A. Some things I'm reading give me the impression the center mount turbo needs special oil galleries in the block I might not have.

Another interesting question I hope someone on here might know the answer to is what's up with the "fuel miser" 120HP engine. Is it simply a matter of turning up the screw? A bigger pump? I'm wondering how specifically gm crippled the engine so I can uncripple it.

 

Do you know what gears you have in the rear end?
The reason I ask is a friend of mine turned a late 90's ambulance into a service truck. It has a 7.3 powerstroke but was still gutless taking off on inclines and towing. Turned out it had ridiculously tall gears. He swapped in a rear from a wrecked F350 (cheaper than paying a shop to upgrade gears) and it made all the difference. I think he went to 4:10 with the replacement rear. I forget what gears the stock rear had.

 

Turning the pump up will give it a little more but probably not what you are looking for, there are other ports you can use to oil the turbo the F&S (vin codes) engines have it on the upper front part of the engine shorter oil line I guess cheaper for mass production

And like burnhedge stated in the post before with a tall gear you will be a disadvantage I have the oddball gear for mine which is the 4.56 it's been awhile but a 27' goose neck trailer weighing 7000lbs empty and my 84 CUCV weighing around 4500 lbs it pulled it respectfully and I am in a mountainous area myself mind you it was no Duramax,Cummins or a powerstroke oh and I do have the NV4500 manual transmission.

 

Thanks for all the helpful replies! Far as I can figure out gm limited the engines to 120HP with a pump adjustment, so i'm going to try that first. As for a turbo, I've read that the "vans" have center mount turbos but as Mayhem pointed out I may or may not have the oil ports for that. But now i'm wondering if there isn't room for a side mount turbo, from the passanger inside wheel well to the exhaust manifold there's a 12-13 inches of room. Here's a pic:

https://www.flickr.com/photos/python...posted-public/

Looking down from the open doghouse. Anyone know how much space I need to fit a side mount turbo in that? Looks like they're easier to get my hands on.

 

You have enough room side to side of the top of my head I would guess you would need at least 10-12 inches above the passenger side exhaust manifold at a minimum and you may have to ad heat shielding to the dog house as the turbo will let heat off it.

I will get a picture tomorrow of where the oil port on my truck and you can look at yours and see if it's tapped.

 

Another option that someone has pointed me toward is the hmmwv turbo. I'm not sure if it's different than the center mount van turbo or not? Maybe different oil port options?

Another question I wondered about is what is the compression ratio of a 6.5 N/A. My burb with a 6.2 IIRC is 21.5 to 1, and I read that 6.5 turbo engines are 18:1. I'm wondering, are the 6.5 N/As the same ratio as their turbo brethren or their 6.2 cousins?

 

You will have to turn it down to 8-10 psi as the turbo will raise the compression even more unless you refresh the engine and do new head gaskets and head studs from ARP.