What's wrong with this

[eventhorizon66]

I was browsing (dreaming) through the GMPP site and looking at the LS9 dyno chart.  I realize this type of chart is never precise, but could they at least have had the torque and hp curves meet at 5252 rpm?

http://www.gmperformanceparts.com/EngineShowcase/dynochart.jsp?engId=LS9&engine=LS9&sku=1920199&engCat=ls

[Irish_Alley]

[VileZambonie]

why would you want it to meet at 5252 RPM? 5252 is just a constant in the calculation HP=TORQUE X RPM / 5252

Peak HP and Torque are graphed on the dyno at their peak rpm.

[eventhorizon66]

why would you want it to meet at 5252 RPM? 5252 is just a constant in the calculation HP=TORQUE X RPM / 5252

Peak HP and Torque are graphed on the dyno at their peak rpm.

If 5252 is a constant, doesn't that mean that the curves MUST meet at 5252 rpm, regardless of the peak numbers?  Of course this is provided that y-axis scale for each is the same.

HP = (TORQUE x RPM)/5252  >  HP = (TORQUE x 5252)/5252  >  HP = (TORQUE x 1)/1  >  HP = TORQUE at 5252rpm

I am I missing something?  Maybe I'm a little dense. 

[VileZambonie]

I think you're looking for a constant from every engine. The constant is used in the calculation. When actually measuring peak hp and torque if it doesn't peak there why would you want to see it there? Now you're making me confused! lol

Peak HP and Peak Torque will happen at different RPM's and should be graphed that way.

http://www.revsearch.com/dynamometer/torque_vs_horsepower.html

[eventhorizon66]

LOL

First, I don't think there is anything particularly special about 5252 rpm, except that if we are measuring power in HP and torque in LB-FT, they should equal each other at exactly this point.  I don't think that they should both peak at 5252, as this would be impossible (unless you set redline at 5252 on an engine with peak torque at 5252 ).  I realize that peak hp and torque figures occur at different rpm (and that one figure is merely derived from the other).  The only reason I brought this up was to question the validity of the dyno chart I posted, because the two lines SHOULD converge (not peak) at 5252 rpm.

So a typical domestic V8 with a stockish cam might have peak torque at 3500 and peak hp at 4500, but if revved to 5252 rpm the torque and hp would equal each other.  Likewise an F1 engine might have peak hp at 17000 rpm and peak torque at 12500 rpm, but the hp and torque will equal each other at 5252 rpm.  They have to, it's built into the formula.

Please tell me you agree with this, and that we got our lines crossed earlier.  Otherwise, I'm committing myself today. 

[Skunksmash]

Dang i thought those engines did a little better than that. Wonder how much they cost? $15K? No one ever buys anything like that cause you can build one with the same power for 1/2 that price. Same with Ford. I wanted some of their top motors for a while for my mustang, but when you get down to it they are just a big ripoff. Just my opinion i guess.

[eventhorizon66]

Dang i thought those engines did a little better than that. Wonder how much they cost? $15K?

Try $20K w/o necessary dry sump oil components, ECM and wiring harness, or accessory drive.

http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=248897

[Skunksmash]

Wow. They really are insane.

[DnStClr]

When your engine is crankin 6800RPM you're going to have to have a good oil pump.
That dyno chart is an eyebrow raiser ain't it? Since torque and rpm are actually calculations of each other, they have to meet at 5252 (the constant). Torque is the power you get, and horsepower is that power in a given time period.

[HAULIN IT]

why would you want it to meet at 5252 RPM? 5252 is just a constant in the calculation HP=TORQUE X RPM / 5252

From the link you referenced...
Horsepower = torque X rpm / 5252
Here's an interesting bit of trivia; below 5252 rpm any engine's torque number will always be higher than its horsepower number, and above 5252 rpm any engine's horsepower number will always be higher than its torque number. At 5252 rpm the horsepower and torque numbers will be exactly the same.
 Just as Even mentioned...the paths on the sheet should cross at 5252rpm's. Peak number's for each will be something else, but the lines should cross. Lorne

[Skunksmash]

Why do they think they need to get $20K for that motor? They must not really care to sell any. Don't they know that the people who would ever even consider it, take great pleasure and pride in building their own? Which is far far cheaper?

[eventhorizon66]

Why do they think they need to get $20K for that motor? They must not really care to sell any. Don't they know that the people who would ever even consider it, take great pleasure and pride in building their own? Which is far far cheaper?

I'm sure they'll sell as many as they intend to.  Those with the money and the "got to have it cause it's the latest and greatest" mentality, will scoop these up.  And to be fair, I'll bet their profit margins on these crates, while high, aren't as obscene as you might imagine.  But yah, you'd never catch me even considering one of these engines, even if I had the $$$.  There are much better ways to arrive at 600+ hp for less.

[VileZambonie]

Ok I just read what you wrote and what I wrote and I apologize, I guess I was thinking you were saying peak meeting at a constant rpm... Yes you are correct, if they are using a precise graph and calculation they should be closer in the ball park where they actually meet.

[eventhorizon66]

LOL.  No prob, but you really had me wondering for a second there.