Horse Power Predicton +/-10% (I think....)

[xctasy]

Great, Whittey, so its out a little over 20% for your bike? Not that good is it?

Remember, Jap bikes rate at JIS, not SAE or DIN horsepower with there factory ratings.

How far out is it really.

 

[Anonymous]

That 120 estimated (while being estimated, I do know a couple gents that have similar and have dyno'd about that. Call it an educated guess) real SAE HP, not some silly damn-close-but-not-exactly-the-same-jis-hp.

But here is one little point that kinda helps your theory. That cam isn't particularly large. It's really the weakest aftermarket web cam for the gs1100. Call it an RV cam.

But you also have to consider that you're generally running less cam in a 4 or 5 valve motor than you do in a 2 valve.


-=Whittey=-

 

[xctasy]

For an average of 1, multiply the sum of the nine variables by 362. For 2, multiply by 250. For 3, multiply by 204. For 4, multiply by 228. For 5, multiply by 265. For anywhere in between, use math or make an approximation.

That 20 (averaging 2.222) should be multiplied by 240. 2.222 is a look-up value of about 240 from the values above. 20*240 is 4800.

Hence 65.6*8000 = 109.3 hp
_______4800.

So its closer within the rules of the game. The head is equivalent to a 0.58 ratio valve, and you are bang on that it should be ranked as a 1. Two 27mm valves is really like one good 38 mm number in a 66 mm piston.

Thats about 10% low, I guess.

(I'm tryin not be too defensive )

What this needs is a tenth term, that of valve lift, or perhaps I should stick with a clarification of the term 'Camshaft Intensity'

What I'm eager to do is have it face-off against a stock computer program like grease_monkey_1966's neat post.

With a little tweeking, and your close scrutiny, we could have a Power Games playoff, X-verses the computer, with your decision final. After all, you've got more qualifications than me. I dig roads for a living, and your the IT man!

Once I've got the charted Hp, the torque curve can be resolved using my former emperical posts. From the past rear wheel dyno information that my Wheels magazines show, I've got a very good way of producing a 12 point graph on my Excel program at work. Did you realise that a power curve is really just a polynomial , y= x2 +2x+x, with a lateral shift and scale factor? I firmly recon that the stuff I've seen on dyno runs may be easily modled from those emperical rules listed here:-

From http://fordsix.com/forum/viewtopic.php?p=18030&highlight=#18030, posted in Feb 17, 2003

In metrics, the maximum torque in a side valve V8 , in Nm cannot be more than 4 times the Kw figure. A 3619 cc Flat head Ford V8 is at this extreme. A quad cam 3929 cc 1974 LP 400 Lamborghini runs in at 268 kw and something like 385 Nm, so it has a ratio of 1.43 Nm for each Kw.

Our Aussie Mustang based Falcon V8's run around 165 kW and 385 Nm. The ratio is 2.33. My friends 351 Cleveland has 149 kw and 415 Nm..which is 2.79

In imperial SAE, net figures after 1972, a sidevalve Ford may have 2 foot-pounds per horsepower. Say a real 73 hp, not 85 gross, and perhaps only 147 lb-ft, not the claimed 160 or so I think I read somewhere, and rev limit of 3800 rpm or so, peak torque at around 1800 rpm.
An Aussie 1982 351C with 200 horses and 306 lb-ft, 1.53 lb-ft per hp, rev limit 4800 rpm, peak torque at 2800 rpm
A 5.0 HO EFI Mustang engine with 225 hp and 284 lb-ft rates 1.26 lb-ft per hp, Rev limit 5500 rpm or more, peak torque at 3500 rpm
A Lamborghini LP400 is 375 hp and 286 lb-ft, rates in at 0.76 lb-ft per hp. Rev limit 8000 rpm. Peak torque at 5500 rpm

See the pattern? Gain revs, always loose torque proportionaly.

Those figures act as a translational shift of the torque curve. I do understand torque makes power, but if its done the other way around from the alogritum above, the results are more accurate. I will set the 9 factors and calcs up in a Microsoft Works spreadsheet, and scale the torque coefficients based on that info above. Then then I'll set these ground rules in stone and I won't be able to change a thing after its locked in.

The results can be charted against a commercial program if you wish.

 

[Anonymous]

Ya got me with the 2.2222 and the 240 vs 275. My fault, i'm illiterate.

As to your RPM & Torque deal. I have to disagree. Torque is a factor of displacement and efficiency. RPM doesn't play much into it at all. In fact, i'd go so far as to say that too low of an RPM will hinder your maximum torque output (stops the air too long(lowers efficiency)).

Lets look at those numbers you've got in a different way.

85hp Flathead V8 = 3.6 liters(221cid) and between 6.12:1 and 7.5:1 compression.
225hp 5.0 HO = 5 liters (302cid) and 9.0:1 compression
LP400 = 4 liters (240cid) and 10.5:1 compression

I couldn't find the aussie compression specs. Lets throw a couple more motors in the mix.

Honda B20B = 2 liters (120cid) and 8.8:1 compression. 126hp at 5400rpm and 133 ft-lbs at 4300rpm.
Honda B16A1 = 1.6 liter (97cid) and 10.2:1 compression. 160hp at 7600rpm and 111 ft-lbs at 7000rpm.

So say we make up a metric like displacement / torque * compression:
221 / 147 * 6.81 = 10.24
302 / 284 * 9.0 = 9.57
240 / 286 * 10.5 = 8.81
120 / 133 * 8.8 = 7.94
97 / 111 * 10.2 = 8.91

That metric, in my head anyway (being as I made it up), seems to indicated efficiency. The highest revving motors have about the same (8.86 average) but the midrange honda destroys the midrange ford for efficiency. I have been of the mind recently that very high rpm is just as bad as very low RPM. Instead of the charge stopping too long, it doesn't have enough time to get going before the valve shuts.

Pro Stocks. 500cid, 1500hp at 10,000rpm and around 18:1 compression. That's 787ft-lbs of torque at 10k rpm. Guess at a peak torque of 1000 ft-lbs at say 7500rpm. By my metric we'd have a unit of 9 (which would seem to support my theory of mid-rpm vs high rpm). By yours it would be 1.5 ft-lbs per hp. I'm not sure whether that helps or hinder your arguement

Forgive me if i'm rambling. It's almost 1am and I just got done leaning against a fence for 6 hours watching cars drive around in circles in 37f (3c) weather.


-=Whittey=-

 

[Anonymous]

I just got done leaning against a fence for 6 hours watching cars drive around in circles in 37f (3c) weather.

:

 

[Anonymous]

Saturday night at the 3/8 mile oval man! I should have worn more than a tshirt and a canvas shirt over that, but it wasn't too bad.
http://www.speedbowl.com/


-=Whittey=-

 

[Anonymous]

I like your math, My engine = (305cid X 4200rpm) / 5500 = 232 HP , It PULLED 232HP on the dyno @ 4200rpm on the nose.

 

[J.R.]

How about the VW Tuoareg V10 diesel:

4.9L / 300 cu.in. (certainly familiar to us Ford I-6 folks)
313 HP @ 3750 RPM
533 LB/FT torque @ 2000 RPM
0-62 mph in 7.8 sec.
17 MPG City / 29 MPG Highway

Even its V6 diesel is impressive:

2.5L / 150 cu.in.
174 HP @ 2000 RPM
295 LB/FT torque @ 2000 RPM

And that is running diesel fuel, which(in all countries but the U.S.) is way cheaper than 87RON gasoline. Suddenly my BB6 with EFI, turbo & intercooling is drastically outmoded!

J.R.

 

[Anonymous]

174 HP @ 2000 RPM
295 LB/FT torque @ 2000 RPM

Which is it? 174hp at 2000rpm is 456ft-lbs of torque. 295 ft-lbs is 112hp.

In any event, I doubt this works for diesels. They run a higher compression, aren't throttled and diesel has more energy per unit mass anyway.


-=Whittey=-