We just did our Dyno test.

[John316]

Yesterday we took the bus in for the Dyno test. That is pretty slick. Turns out that our engine is tuned down to 400hp (which is fine with us, it works, and better MPG). We had 320hp hitting the road, and the guy told us that 80% is great for a bus. The other 20% was just in turning the wheels, differential, tranny, etc. They said that the turbo was healthy, and compression was good. We had an oil sample, and a coolant sample sent off to be analyzed.

All in all, turns out to be good news.

We are trying to decide if we do any preventative maintenance on the engine (bearing, seals, etc). 

God bless,

John

[johns4104s]

John,

Who did the Dyno and what did it cost? How do they do it Over a set of rollers or what?

Thx

John

[TomC]

On a S60 you really don't need bearings until 1/2million miles.  If you can drop the pan easily, it is a relatively cheap job ($500.00) and gives good piece of mind.  Good Luck, TomC

[paul102a3]

We had our bus on the chassis Dino before we purchased it. Our 8V92 is tuned for 400 HP as well but we were only getting about 220 at the wheels. It turns out that the boost pressure sensor was not functioning (the hose was split in half) so the DDEC module would not allow full fuel flow.

The technician gave me a similar HP figure of 325 at the wheels with everything ship shape.

The Dino at the DD shop here in Tampa was in a pretty neat building. They bring the vehicle into a separate building which is made of reinforced concrete. The main building has a small bunker off to the side that houses the recording computers. The floor has recessed tracks that hold straps to bind the front wheels to the ground and the drives sit on top of large rollers. The tags just sat on the ground as they normally do. They chained the trailer hitch to a recessed ring in the floor to try and prevent the rear of the vehicle from moving sideways on the rollers and to act as a safety should the wheel straps fail.

The building has some small, very thick windows so you can see the action however they no longer allow customers to watch as they have several tire failures. The shop manager told me it was real exciting when a drive tire blows at 70 MPH.

The resistance for the rollers comes from a 5,000 gallon water tank located outside the building and is controlled from a remote that tech takes into the bus with him. I get the impression it is quite a chore to balance the resistance of the rollers along with manageing the shift points of the transmission. If they don't build the resistance just right as the engine is accelerating, they have to stop the test and start again.

While the technician ran the bus through it's paces,  I was in the bunker watching the outputs of HP, torque, oil & water temps, etc, on the computer.

On my bus they ran it up to full MPH which is governed by the DDEC at 75 MPH. The tech did this twice to get repeatable data.

The test lasted 6 minutes which is their limit for buses to prevent cooling issues. As the tech said to me, the bus is under full load going 75 MPH but standing still. There is not enough air flow to prevent overheating.

The total cost to me was $380.32 which covered the Dino test, oil and coolant samples, reading the DDEC history, and general survey of the engine and transmission.

I did walk away with a nice set of graphs showing the performance of the engine and shift points, etc.

[Chuck Newman]

On a S60 you really don't need bearings until 1/2million miles.  If you can drop the pan easily, it is a relatively cheap job ($500.00) and gives good piece of mind.  Good Luck, TomC

Tom,  is that recommendation the same for the S50 engine?  Thanks,

Chuck

[John316]

Yeppers,

Paul has it pegged. Except ours wasn't that high tech. It wasn't in it's own building, just in a separate concrete bay. The brake for the wheel was broken. They feller pulled it up, and the tire was on the solid metal a little bit. Walla, they had to pull it back off. They got a GIANT forklift (from the generator side of their operation), and pulled the bus off. The bright bulb then backs it on again, IN THE EXACT SAME PLACE . Again comes the forklift, and pulls him off. We offered to back it on right, and the guy says nope he can do it. Finally he gets it right, and they chained it in place. It was really neat. It is also kinda scary. Can you imagine a 20 ton rocket pulling out of there at 75, if something goes wrong? Wheeww.

What are indications that our bearings are going out? From my talk with PP, they said that they did a partial rebuild (including injectors). Would they have done the bearings too? Sounds like we are due to get those replaced, then....

God bless,

John

[johns4104s]

John,

Who did the Dyno and what did it cost? How do they do it Over a set of rollers or what?

Thx

John

[John316]

Central Power did ours, and they are usually 350 (they gave us a break because of the guy messing up, and taking longer). They pull the vehicle up on a set of rollers, and simulate it driving down the road. Then they check the health of the drivetrain.

God bless,

John

[RTS/Daytona]

here's a related Dyno post - for you 6V92TA guys

http://www.busconversions.com/bbs/index.php?topic=10469.0   "Poor Mans Dyno"

[TomC]

S50 engines, should be done a bit earlier since they are subjected to more vibration.  I would roll bearings in at 400,000 miles.  AND- while the pan is down, replace the gears for the silent shafts that run off the oil pump.  Good Luck, TomC

[luvrbus]

John316, DD has no set mileage on new bearing on a 60s the only time they recommend it is a at a overhaul.
The bearings in a 60s will out last the rest of the engine.
I have saw 60s with 700,000 miles and the bearing looked new( the rest didn't) save your cash and spend it on other things.
Call Valley Power in Ca and they will tell you the same.   

good luck

[John316]

Clifford,

Great to see you back!!! I have missed you!

Thanks for the info. Good advice. I think that we will save our money, and see how much we can sink into some couches .

God bless,

John

[JohnEd]

Clifford,

What John said.

John