Understandably, when a specific model of car/truck comes from the factory, they issue horsepower results at the flywheel, yet in the real world, when a Dyno run is made on a vehicle, it is done at the rear wheels.
I've heard anywhere from 18% - 22% loss can result in a loss of HP through the running gear....so who is "correct" in their manner of showing HP results?

I'm sure when advertising a HP rating, the higher the better...and perhaps most don't realize that it is "flywheel" horsepower that is being advertised, but in theory that is NOT the HP that you will get "at the road", thus it is a lie in my opinion.

Shouldn't everyone be on the same page, and be giving out "Rear Wheel" Hp ratings?

My truck came in as 215 HP on the engine sticker, which is obviously "flywheel" HP, so figuring that I now have 390 "rear wheel" HP, is there an exact figure used to figure where I'm at at the flywheel? There must be more to it than just adding in the 18% - 22% factor?

Thanks...

Dale

 

just another way the "stealerships" try to dupe the public... and they get lots of help from manufacturers... don't sweat it... now that we have the internet... these folks are going to find it harder and harder to get away with this stuff... becuase the car and truck buying public are a little smarter everyday... i wish i had known about this site before i bought my truck, but now that i've read a ton of posts hear.. i know what an awesome mule i got...!

 

Hmm. I would say that it really isn't "lying" because the measurements they are making are true. Yes, crankshaft horsepower always sounds better because it is so much higher. But the reality is that they (manufacturers) ARE ALL on the same page because they all report crankshaft horsepower measured more-or-less the same way.

So there is basis for comparison from one manufacturer's vehicle to another - not precise, but it is some basis for comparison.

As to why we measure rear-wheel horsepower - we can't easily measure crankshaft horsepower, since the engine is in the vehicle. The only recourse is to measure with a dyno.

As for calculating crankshaft hp after mods when measuring with a rear-wheel dyno? Who cares?

Best way would be to get a baseline, unmodified rear-wheel power measurement, then dyno after. Then you find out your actual measured and percentage increases. Crankshaft hp is irrelevant after you make your new vehicle purchase decision.

 

crank hp is a more accurate measurment. roller dynos are no where near as accurate due to roller wieght type of tires, gearing,...........

crank hp is something that will always be the same due to thoose variables that arnt there. and for epa regulations they requier crank horse for classifications.

 

Yep. Lots of reasons for crank hp measurements - not just lying manufacturers.

 

I can attest to getting different results at different Dyno's, as they all seem to load differently! So, who is correct...I guess we'll never know, but often most are fairly close to one another. Then there is the "correction factor" of which I don't understand.

I've Dynoed several times...all on the same Dyno, so I know where I once was, and have (over the years) slowly worked up from there, and now know where that same Dyno puts me know.
I'm currently happy with my power output, but now just want to lower my EGT's some more (need a larger output turbo) with some chip programming perfected, and I should be all done, and just be looking for longevity from my old '95.
Still hasn't hit the 100,000 mile mark yet, so I'm hoping for alot of good years out of her yet.

Dale

 

need a H2E....

theres just too many varibles going to the rear wheels.

 

What?? You?? Never. As a matter of fact, earlier today you told Brian at B-D:

I know you too well, Dale. You won't stop at 400, or 450.

 

again theres no such thing as too much HP!!!


dale gotta get that H2E......

 

....or, too much is never enough!!

 

Quad buddy....I really do believe I'll be stopping at 450 RWHP, as there have been too many stories associated with going over the 500 RWHP mark, and I personally believe the longevity ceases big time if using the high end power on a consistant basis in these Powerstrokes. They just where not made for the top end HP ranges seen today, unless the engine is pulled, you O-ring the block, change to stronger pistons and rods. I don't want to do that, so I need to have a stop-gap measure...being 450 RWHP for me.

May be less...don't know, but we'll have to see when an H2E goes on.
I don't mind a bit of smoke, but it can get crazy at the moment if the engine is lugged.

I'm working on (suppose to be hush hush) getting an H2E or HX55, which may be able to adapt to our stock collector and up-pipes, but it is still in the research stage. There is one version out...but it is being "massaged".

At any rate, it needs to be "affordable" or it won't be done, as my lovely wife is watching the funds a little too closely.
I say...good for her, as the prices of a new kit are totally ridiculous really.
I can't see spending nearly a quarter of the cost of the truck in just putting a new turbo on?

By the way bud...shouldn't you be filling boxes and packing?

Good to see you on the 'puter bud!

Dale

 

Since I don't know the schedule for when I'm actually moving, I'm getting as many other things done until I know more. I've got Sue's car ready to be put on a transport so I can get that down to her, and will be meeting with a rep from the moving company today, so things might start moving after all.

 

so we will see yall down here soon......