[DMCForum] Re: performance engine specifications (Rick G)

["content22207" <brobertson@xxxxxxxxxxxx>]

Do the math: a hypothetical little engine rated at 400 HP @ 7,000 RPM
is producing 300 lbs of torque at that point. 

A stock Ford 460 produces ~375 lbs at idle, rising to 425 @ 2,500 RPM.

Don't know the exact specs for a GM 500, but I'm sure they're
comparable (with the caveat that GM Big Blocks always had a sharper
torque curve than Ford -- sorry).

That's one of the falacies of buzzy little engines -- until they rev
up, they are basically powerless. Even then, how much of your energy
is basically kinetic versus real power?

I've said it a thousand times before: you'll never see a high HP
sports car towing a boat trailer.

Bill Robertson
#5939

>--- In DMCForum@xxxxxxxxxxxxxxx, "twinenginedmc12"
<twinenginedmc12@xxxx> wrote:
> 
> Hi Bill.
> 
> 
> I did not know that my rear engine has more torque at idle than a 
> turbocharged PRV would have at full throttle.  That's a fun little 
> statistic.  Thanks for that.  I know it has enough torque to be scary.
> 
> Yup, I included the front engine in the calculations. 
> 
> 135hp net front, 315hp net rear,
> 
> 160 brake front, 400 brake rear.
> 
> My net figures are a little conservative.  I suspect the brake 
> figures are not.
> 
> There is a lot to be said for light engines that rotate faster, too.  
> I expect that when that Lotus V8 twin turbocharged equipped Delorean 
> is operational, I will no longer have the fastest accelerating 
> Delorean in existence.  I believe that lighter and faster is better, 
> but I designed my car for bulletproofness, which is also better, I 
> guess.
> 
> Rick.
> 
> 
> --- In DMCForum@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> 
> wrote:
> > 
> > SAE change was made in 1971, I think (about the same time 
> compression
> > was dropped across the board).
> > 
> > If Houston simply bumps compression up to Euro spec 9.5:1, that 
> alone
> > yields 15+ NET horses.
> > 
> > I believe their dyno graph shows the red line moved closer to 7,000
> > RPM, which would indicate some sort of change in the valve train.
> > 
> > Freer flowing exhaust should be worth 5 or 10 HP.
> > 
> > Don't forget: HP calculation depends on engine speed -- all Houston
> > has to do is figure out a way to get 500 more RPM out of the PRV, 
> and
> > HP goes up 10% on that basis alone.
> > 
> > BTW: are you including the Prelude engine in your claculations? The
> > high compression 500 should be ~390 gross HP. That's 390 HP @ ~3,500
> > RPM (which could almost double if you modified the valve train to 
> spin
> > even faster). You do realize your 500 is producing more torque at 
> IDLE
> > than even a turbocharged PRV will ever produce at throttle.
> > 
> > Bill Robertson
> > #5939
> > 
> > >--- In DMCForum@xxxxxxxxxxxxxxx, "twinenginedmc12"
> > <twinenginedmc12@xxxx> wrote:
> > > 
> > > I'm sure the DMCH performance engine is a fine engine, but it 
> should 
> > > be noted that the power specification they publish does not 
> > > accurately compare to the stock specification.
> > > 
> > > The OEM stock engine was rated 130 hp "NET", by law, which means 
> the 
> > > reading is taken with all accessories like water pump, 
> alternator, 
> > > air conditioning, intake, exhaust, etc, connected. 
> > > 
> > > The DMCH performance engine is rated 197 hp "BRAKE", meaning the 
> > > reading is taken with no accessories connected.  There doesn't 
> even 
> > > have to be coolant in the passages.  In the nineteen seventies, 
> the 
> > > Society of Automotive Engineers (SAE) abandoned specifying brake 
> > > horsepower (BHP), because it does not accurately reflect the 
> power 
> > > available to move the car.  
> > > 
> > > Unless Delorean in Houston starts specifying their performance 
> engine 
> > > in NET horsepower, it's not possible to intelligently compare the 
> two 
> > > engines.  I consider DMCH specifying their horsepower in BHP 
> either 
> > > misguided, or somewhat deceptive, depending on their motives, in 
> that 
> > > it leads people to believe the performance engine is more 
> powerful 
> > > than it is.  This is precisely why the SAE stopped specifying 
> power 
> > > this way.
> > > 
> > > 
> > > Rick Gendreau 11472 
> > > twin engine Delorean, 560 brake horsepower, 450 net horsepower, 
> Gosh, 
> > > what a fun car.

---

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