What Hp does your car put to the rear wheels?

[Jay Wolf]

The Student Auto Club at Vincennes University is

having Spring Dyno Day March 29, 2008 from 9AM till 5 PM

$40/ 3 pulls

Located in the VU Automotive Building on the Campus of Vincennes University in Vincennes IN.

For more Info Call 812 888 5316 or TFreed@vinu.edu

No Charge to watch and everybody is welcome all proceeds for the Auto Club projects.

Antiques and Classic welcome. You don't have to have a preformace car to wonder what is meeting the ground.

[Matt Harwood]

I used to work for a dyno manufacturer. I took my father's 1925 Buick Model 25 touring (which was sold to a board member here, I think) and ran it on the dyno. Aside from being a little worried about breaking those ancient wooden spokes, it worked pretty well. Put it in third and went gently to full throttle and let it pull until I thought it was spinning fast enough (about 75 MPH).

Results? 48 wheel horsepower, 108 pounds of torque. The horsepower is about what I expected, but I thought it would make more torque. Either way, the car worked pretty well on the street for being so modestly endowed. And remember, this is wheel horsepower, not flywheel, so there are going to be some (significant) losses between the two.

Dyno runs can be a lot of fun, but be prepared to be disappointed with the numbers, <span style="font-style: italic"><span style="font-weight: bold">especially</span></span> if you have a musclecar. Everyone with a healthy V8 figures they have at least 400 horsepower. More often than not, the dyno tells them they're only making 180-200 at the wheels. I've seen more than one guy get very upset about it.

[novaman]

Not my old but, my 2001 Dodge 3500 5.9L diesel 2WD is rated at 168HP putting 204HP on the ground @ 74 MPH. Haven't done anything performance wise to the truck since the day it was delivered from the dealership.

[Matt Harwood]

Diesels are a strange case, especially turbo diesels. Depending on the type of dyno, turbos may not make full boost under test. Most turbos need a load to make boost--a spinning inertia drum won't create enough drag to load the turbos.

Novaman, I think your truck's factory rating is wrong. According to my Ram's owner's manual (which is my only frame of reference because I ended up with the 5.9L gas V8 for mine--dummy), a '98 Dodge Ram 5.9L I-6 diesel was rated by the factory at 215 or 235 horsepower. I don't know why there's a spread--must be a transmission thing or whether it's a 4x4 or dually, perhaps. But I think it's unlikely that just three years later, it had lost more than 75 horsepower. Sounds like your truck is making exactly the numbers it should if it was rated at 235 HP.

I don't understand the MPH part, however. It should be at an RPM. MPH is purely arbitrary on a dyno test and has little to no bearing on horsepower as long as the engine can be tested through its entire operating range. If you stopped at 74 MPH but the truck will run to 90, then it may very well have made even more power with more RPM, though as a diesel, it is probably done by about 2500 RPM. This is also why rear gears have very little effect on final dyno numbers.

When I mentioned MPH for the Buick's test, that was the only gauge I had to keep the engine from tossing a rod. With no tach or any idea how fast the engine could safely spin, I figured that the car could probably attain 75 MPH in the real world under perfect conditions, which I assumed would be close to the outer limit of its operating envelope. Note that max power was actually made quite a bit earler than my arbitrary "redline".

If anyone goes, post the numbers here. Modern cars and dynos are boring. I'd like to see what some of these unusual old cars put out. I wonder what a Duesenberg SJ's power curve would look like?

[Jay Wolf]

We have a Dynojet 48" in floor and currently do not have the device that put a load on a turbo diesel so they will build boost and give accurate hp rating. One of the things the club hope to purchase from the income from the events like this is the $1200 Electronic brake controller for turbo diesels.

Last year they bought the crank sensor so the could run diesels at all, before that if we could hook on a plug wire we could get any reading at all.

There are some videos of some dyno 2005 runs for at.

http://beaver.vinu.edu/11-05-2005%20VU%20car%20show/index.html

[novaman]

I just looked at the data tag on the engine it is a 5.7B-160hp. I know it a lower figure than the manual transmission trucks for '95.

I know the Hp is RPM related I just forgot what the RPM is at 74 MPH. The reason the MPH sticks is my parents have been on me from day one about speeding in the truck, (and I'd be doing 74 MPH). The truck was run on the dyno at cummins in Greensboro. I told dad "now you see why I'm always running 74 MPH!"

[Matt Harwood]

Ah, that makes sense, Novaman. Since you were testing at a Cummins facility, they were looking for the engine's most efficient operating speed. That's probably A LOT more helpful for towing in the real world than a dyno sheet showing you a power curve. Like you said, set it at 74 MPH and forget it! I never thought of it that way, even when I was doing it for a living. Very smart.

[novaman]

They gave me the dyno info but I can't seem to find it. It's been several years ago when they dd it. What stinks is I have the 3.53 rear and the problem there is at 55mph I'm on the very bottom of the power range and I get to a hill, I'm slow going up. So I got to watch the road to keep the RPMs up for a upcoming hill. The first time I dorve it loaded was through the hills in central VA (Rt. 29) and I couldn't figure out why semis were passing me going ujp a hill. I dropped in between two rigs and mirrored them for about 15-20 miles and figured out how to drive that diesel. Found that putting the throttle completly on the floor wasn't always the fast.

[R W Burgess]

Gears, David, Gears!

That's what keeps those semi's pulling over the hills. I've got an 18 speed that has "long legs", but in the mountains of West Virginia and Pennsylvania, I keep it down a couple of gears in the box around the heaviest part of the torque range, blows right by those also rans.

[novaman]

I know. What I had found tailing the semis was I needed to stay above 1500 RMP, when I needed cut the O/D on and off, etc. to keep the RPMs up but no run over the top of the HP curve with too many RPMs.

[Ivan Saxton]

I have another set of figures from an antique, if you are interested. I have just skoken to Ken Stuchbery, who has a short chassis BB Stutz with replica 2 pass Black Hawk speedster body. It has a camshaft reground to give about 20 degrees overlap, from memory; and the piston pattern work I had made gives around 6:1 compression ratio, from memory.When tuning it on the dyno, they got 110 hp, which Ken said they reckonned corresponded to 125 at the flywheel.

(I would have guessed the drop would have been more than that.) Interesting thing is that they had to discard the 25mm main venturis to get enough air through.

Really those big straight 8's were handicapped by the difference in flow path for the end pairs of cylinders compared to the four in the middle, and mixture strength probably varied more between cylinder than is ideal.

Ivan Saxton

[Rusty_OToole]

I take it this is a late 20s Safety Stutz with the single cam engine? I believe the factory claimed 92HP?

Did they offer a modified engine for the speedster? I know they had quite a battle with Auburn for the stock car title in 1925 or 26 but don't recall if they offered a modded engine at that time.

[Ivan Saxton]

Yes Rusty, that is correct for the AA series which started in 1926 with 3 3/16" bore, and Timken hydrostatic brakes. (Those had reinforced "rubber bag" elements and used water/alcohol mix. Ken has been able to get an old bloke in the industry to make new sets of these for people with water brakes on their cars so they could remain original.)

Bore size increased to 3 1/4" before the next model in 1928, which was called the "Splendid Stutz". The specific identification is not neccesary in this thread, though often changes did not coincide with model changes.

However, at some point they produced engines with higher performance, essentially first for their competition activities. There were higher compression ratio options, and some engines had HC engine number prefix. Original Black Hawk speedsters may often have had "HC" engines.

A most important difference however was a different camshaft, which allowed the engines to pull to 4000rpm. The BB was listed as 115 bhp, but this was fairly nominal. We should remember that Frank Lockhart was associated with Stutz during their competition efforts until he died in his car (that he built in the factory) at Daytona Beach. It is likeley that he had some influence in the creation of the DV32. The engine for my Black Hawk replica has a "SPECIAL"

BB style block with 3 3/8" bore, , a casting date for 27th of June 1928, and engine number DV30004, which predates the M Series. Now some engineer among us may be able to exlain why the centre main bearing cap of a 9 bearing straight 8 should be prone to breakage. I can show three engines side by side, with casting dates from March to June 1928, and they are different. #91845 has a sngle rib on the centre main bearing cap, 92335 has a stronger on with two strengthening ribs, and DV30004 has massively strong main bearing caps that I have never seen on another Stutz engine, even M Series. Stutz must have known they had a problem. A few years ago Geoff Ringrose from Sydney started out on a club event in his BB, (which has an engine number close to #91845), when it developed a bad knock. He trailer it straight home, and the centre main bearing cap was broken. Now it has always been a matter of doubt and speculation what happened to cause the failure of the Stutz in that match race with the 8 litre Hispano Suiza at Indianapolis. If they broke a centre main bearing cap, and felt they had to keep going, they would have ended up with no oil pressure to the conrods that were fed from it. (I'll check which way the oil feed holes run on a crankshaft later.) Eventually, no horsepower at the back wheels.

Sorry I strayed from the topic, but I thought you might find it an interesting sidelight on history.

Regards, Ivan

[Jay Wolf]

This is this Saturday.

It's free to observe

If any of you can make it look me up.