mark kibort

I was looking to get an appointment for a dyno run to see how things are running with the stroker, and it turns out Musang ranch went out of business (has a 248e dynojet) that dyno has been around the block a few times over the past 25 years.

Does anyone know where it might have ended up, or if there is another popular dyno in the bay area?

At the track, i did a dyno a year or two ago with a dynojet, but it was the one with the smaller drums.... (portable unit) The HP results were very close to the Dynojet 248e.

mk

MrAngry

Hi Mark -

TFB Performance at Sonoma Raceway. My car '86 is there now getting serviced. Tim Barber is the owner and has dyno'd a few of my cars. Nate, one of their head techs, is also VERY knowledgable on 928s and is one of the few people I would trust to work on my cars.

Hope this helps.

Mike

Speedtoys

Drum size makes no diff.

MCE will be at Thunderhill this coming weekend for the 25.

I -think- TFB still has theirs too.

mark kibort

thanks,

Ive done a few with MCE, so i know about them. TFB??. probably wait until the first race of the year and just run with MCE... they were at T-hill at the last race, but i was in a hurry to get the kids back, so blew it off to go to Mustang ranch.........but chapter 7 got them ! so, Ill wait for MCE, unless they have a dyno at Cal speedway in january.
i thought there was a few in the bay area. dynospot, mustang ranch and another. i guess not

as far as drum size.........yes, it does matter. you can't totally ignore a major element of the physics, rigtht? What a small drum size does, is that it allows itself to to accelerate faster, thus making any ineratial factors in your driveliine/wheels/tires, etc,, more of a factor than they might otherwise be. make sense?

also, i have noticed with the smaller drums, they spin at a much higher RPM and are much more susceptible to vibration,which can effect grip (slip) and power.. the key difference is the rate of acceleration. if you match what your car does in 4th gear as far as rate of acceleration, (say, 9seconds from 60mph to 150mph in 4th gear on a dynojet 248e), then run on a dyno that allows for acceleration of half that time, the inertia effect (loss) is much more pronounced. It's one of the reasons that 3rd gear runs produce less HP than 4th gear runs. (part not all. Gear efficiency goes down as the reduction ration goes up as well)

thanks Mike.. i know Tim . I think ive heard the dyno howling during the race day!

Speedtoys

No, it doesnt matter.

Its just math.

Neither drum size is the same as road load.

22", 24"...same reading assuming same output...which no car will exactly ever replicate..

mark kibort

Yes, it is math, and half the weight, will mean less inertia which means for the same rate of doing work (HP) you will accelerate the drum faster. and the faster you accelerate the drum, the more the negative effects of any system inertia of the driveline. i never said drum size equal road load.

the drums on a 248e vs the drums on the MCE dyno (24" ) is half the diameter and a fraction of the weight. IF you accelerate the drum factor, all the inertia of the driving system, will be effected by it. By saying it wont, is equivalent to saying a 3rd gear run will be the same as a 4th gear run... same logic..........and it's clearly wrong.. ..........help me understand if i am misunderstanding you... (go do the math of a set of drums 24" diameter vs 48" diameter ........the 48" drums weigh near 3000lbs (each ). what do you think the 24" dia. drum weigh? )

It's simple math. the faster you can accelerate the drums, the MORE the inertia of the driveline, engine, wheels, tires will effect HP output.

Let me give you an example to help you understand the concept. if you had a 20lb flywheel vs a 5 lb flywheel, both would require less than 1hp to accelerate them from 3000, to 6000rpm if the acceleration took 20 seconds. the heavier flywheel would have a higher cost than the lighter one. Now, if a dyno run took 3 seconds, you use your "simple" math to calculate the HP required to accelerate both flywheels. THAT would be the cost in HP on the dyno. its usually, not a lot, but i can assure you, it is not "nothing".
I see about a 5hp difference between using a small diameter drum dynojet, and the large diameter dynojet , and this is what i have seen by doing dynos 1-2 times every year for the last 10 years on this engine and all my dynos have been in a 1-3HP range of consistancy. (which is not due to the dyno , as you either accelerate the drum at a certain rate or you dont. )

V2Rocket

gotta be a few dynos around los altos for all the techies to dyno their toys.

****, call sharkwerks in fremont.

Speedtoys

Ya...Mark...

You're the guy that would argue at a tech station dyno about why you REALLY didn't break the class HP limit Cuz your home dyno is better. But still not the dyno youre told to expect.

But, give/take the <5hp difference in those physics, the 224x is the better dyno. Its more popular.

Ducman82

math is math............... small or large diameter, convert it baby

Speedtoys

Well, he -has- a point.

But it only matters for HP trailer queens.

One should always use same setup for tuning and/or compliance results.

I get a lot of 'my dyno at home reads different'...and it's no excuse.

mark kibort

You must have missed the "point". you said there is no difference ("no" difference) . I used your "simple Math" to show you that there is a difference and it is NOT limited to trailer queens. sure,dyno results are all over the map usual, (within <1%) due to differences of the dyno run. (air pressure in the tires, strap down force, and the most common variable, just the engines adaptive conditions that change spark, mixture, constantly or to the best of their ability) BUT, the point is.............. a 248e differs from a 224 model because the drums are near half the weight and 1/2 the diameter. just a standard run accelerating the rolling mass from 800 rpm to 1800rpm (4th gear dyno run on a 48" roller) vs 2 x that RPM over the same 4th gear RPM range of the engine, would create 3-5hp in some cases. BECAUSE IT SPINS UP at a fraction of the time! (hp is work per unit time) knowing that, i prefer to use the lower HP reading for class qualifications, and the larger diameter rollers for just knowing a more accurate value. Most important, it allows me to compare previous dynos that have fallen in a narrow range of about 2-3 hp to see what has changed. (on similar days, with all factors i have control of , controlled)

personally, i dont like the small rollers.......which is the main reason i brought it up. it tends to induce more vibration to the dyno run and that can be a factor in 5th gear breakage.


not only is it small vs large diameter, the MASS is less than half! its a pretty big deal actually.

Actually, you got it backwards........the track dyno will be to my advantage vs what i see on a 248e. it will read lower, due to 2x the faster acceleration rates (because of the lower mass AND diameters). if you work out the "differences " im speaking off, it might be more than 5 hp too........... add up all the rolling weight after the transmission for example........use the tires and wheels of 100lbs , 1ft radius (standard wheel and tire radius) . figure out (using simple math), what the difference in HP is , taking that rotational mass from 800rpm to 1800rpm in 4 seconds vs 8 seconds. and you think lighter flywheels , AC, and alternators have an effect on hp measured at the dyno? run the calculation and let me know what you find!



I think you can understand that now........... as far as better or worse? popular doesnt equal better. better is usually, not as popular, because it is more expensive and not as convenient.

mark kibort

Sharkwerks.... good chance, so ill call. thanks!

mark kibort

Here is the dyno run from 3000rpm to 6500rpm. Takes about 8.5 seconds
I'm looking for the smaller roller dyno 224 model video.

Remember, the effect of running to redline with all the driveline, engine, clutch , flywheel, inertia as well as tires is significant. (50lb crank, 40lb clutch/flywheel, etc) its all based on time... and its also based on HP available.

Ducman82

i get the using the same dyno each time. consistence and all. MASS, diameter.... all should be equated in the programming already. ya, dynos are ALL different beasts, but follow the same principle. was what i was getting at.

SwayBar

Mark, have you seen Carl/Catorce's new intake results on Carl's 6.54L motor? Here's the link in case you missed it, you may have to scroll down a little:

https://rennlist.com/forums/928-forum/961748-highwayman-bringing-the-devore-928-back-from-the-dead-55.html

What are you thoughts regarding its power output?

Do you think it's advantageous for the horsepower to continue to climb all the way to redline, and particularly for use on a track car?

What kind of numbers do you think you'd get at the wheels with your Green Bay stroker?

I don't know, maybe after all these years you've simply accepted the performance of the stock manifold on your stroker?