TORQUE!

[Ted Jenkins]

You certainly did not build any drag race engine I could think of, to be run at 20k to 25k rpm. I believe, even 180 degree crank V8's, like Indy cars, don't get that high. Inertia is one thing, exactly how that inertia is/was created is another. Try running a clutch made for top fuel in an alcohol engine and you will quickly find that plain inertia alone does not explain all that takes place. The same piece of metal at the same rpm can behave much differently depending on the source impacting it. Source + inertia = power output? Different sources were what was being discussed.

Thanks so much for your insight on motor builds. I am not really interested in exchanging in an insult spree. So hope you are producing big heavy chips. https://www.bennetts.co.uk/bikesoci...tures/racing/10-most-extreme-6070s-race-bikes Thanks

 

[Ted Jenkins]

You certainly did not build any drag race engine I could think of, to be run at 20k to 25k rpm. I believe, even 180 degree crank V8's, like Indy cars, don't get that high. Inertia is one thing, exactly how that inertia is/was created is another. Try running a clutch made for top fuel in an alcohol engine and you will quickly find that plain inertia alone does not explain all that takes place. The same piece of metal at the same rpm can behave much differently depending on the source impacting it. Source + inertia = power output? Different sources were what was being discussed.

Thanks so much for your insight on motor builds. I am not really interested in exchanging in an insult spree. So hope you are producing big heavy chips. https://www.bennetts.co.uk/bikesoci...tures/racing/10-most-extreme-6070s-race-bikes Thanks

 

[Ted Jenkins]

I think it’s important to compare power band location in the saws mentioned and examine the timing and design of each cylinder.
What changes crank and flywheel weight have on the pulling power of the saw would be best observed if one model could be modified to fit them all but that’s an insane amount of work or impossible.
I’d love to see all the cylinders side by side and a good spreadsheet of port numbers. (With compression specs).
At least hang the same bar on all of them and make some cuts. Sounds like a good GTG.

I can not even imagine the complexity of engines, cylinders, stroke, port timing, ignition timing, and the influence of exhaust flow for a chain saw. Just looking at the top selling saws of today maybe 10 or so would be quite a large amount of data. Rule of thumb would be to consider stroke influence on overall performance. A longer stroke produces more torque vs. a shorter stroke produces more power and RPM. Manufacturers study these issues probably until they want to quit. Thanks

 

[Ted Jenkins]

Thanks Mr. Jenkins, you said what has already been said using a lot more words while posturing and condescending to all.

and condescending to all Your welcome Holy Thanks

 

[Ketchup]

Seems like the big three talked about here are 090, 880, 1201. Compare:
Stroke
Displacement
Port Timing
Port Area
Stock compression
Squish
Clutch size and weight
Flywheel size and weight
Torque ratings


A simple spreadsheet would shine a lot of light.

 

[ferris076]

Stroke has nothing to do with torque.
Here are some data.


090 has 8.6 HP with 9.5 Nm (7 ft-lb) of torque at 137cc. Bore 66mm Stroke 40mm

070 has 6.5 HP with 7.7 Nm (5.7 ft-lb) of torque at 106cc. Bore 58mm Stroke 40mm

075/076 has 7 HP with 6.8Nm (5 ft-lb) of torque at 111cc. Bore 58mm Stroke 42mm

 

[Robin Wood]

Stroke has nothing to do with torque.
Here are some data.


090 has 8.6 HP with 9.5 Nm (7 ft-lb) of torque at 137cc. Bore 66mm Stroke 40mm

070 has 6.5 HP with 7.7 Nm (5.7 ft-lb) of torque at 106cc. Bore 58mm Stroke 40mm

075/076 has 7 HP with 6.8Nm (5 ft-lb) of torque at 111cc. Bore 58mm Stroke 42mm

Stroke has to do alot with torque
That comparisons above arent even, they have different designs altogether.
075/076 is vertical design with lighter reciprocating mass. 070 and 090 have heavier reciprocating mass and bigger case with big carb, 090 6 piece clutch. That could be the biggest clutch in any chainsaws ever made, that weight alone will add some power.

Cs1201 7.5hp
58mmx44mm @116cc 9nm torque

Sent from my INE-LX2r using Tapatalk

 

[Huskybill]

A longer connecting rod with more stroke equals less rpm, more torque.

 

[sawfun]

A longer connecting rod with more stroke equals less rpm, more torque.

The longer rod in the same length stroke, means more dwell time so it generally allows for more time for fuel and air to enter. This does not necessarily mean less rpm thoufh, and fuel burning rates really need to be taken into account at this point. Most of what we consider high torque engines tend to have longer strokes and rod lengths. I find it easiest to think of a longer stroke crank throw as being further from the centerline of the crank thereby have a greater leverage capability. Peak cylinder pressure vs cylinder pressure over a longer duration can also have a huge effect on the type of power exhibited.

 

[Stihl 041S]

Thanks so much for your insight on motor builds. I am not really interested in exchanging in an insult spree. So hope you are producing big heavy chips. https://www.bennetts.co.uk/bikesoci...tures/racing/10-most-extreme-6070s-race-bikes Thanks

You were building these engines when you were 14-16 years old?
Or doing restorations later in life?

 

[Ted Jenkins]

Stihl I am not sure what my age had or has any thing to do with torque or my passion for racing motorcycles. This is the short version of my evolution. When I turned 11 I bought a 50 CC Yamaha motorcycle and just plain enjoyed it while riding. Before a year had gone by I discovered GET Parts or Genuine Yamaha Tuning parts which were your average road racing parts. After many burned pistons and various engine failures I went to 125 CC class bikes winning several top eliminator awards drag racing in the process. My most favorite endeavor was my stock looking AT-1 turning in consistent 13.5 ET's. Athena Oregon was just an hour drive from my house where I met and got to know the R&D of PABATCO Hodaka which was one guy who knew a great deal about two stroke tuning. Ascot 250s were plentiful and cheap because few could figure out how to tune them or keep them running. During my teens I built all kinds of configurations using them. Then when the H 1 2 and 3 came out running 10 sec ET was very easy. When I turned 16 I bought a dealership which opened up many door doors for parts and bikes in the process. Then in 1973 we experienced the gas crisis so my starving enterprises quickly turned towards making a living rather than going fast. The best job offer was with the USFS designing roads for timber sales. Thanks

 

[Stihl 041S]

I asked about your age when you were working on these because the very high end 20,000+ rpm Japanese engines were being used when you were rather young to be with Team Honda.
And I thought you did restoration

 

[Ted Jenkins]

I asked about your age when you were working on these because the very high end 20,000+ rpm Japanese engines were being used when you were rather young to be with Team Honda. And I thought you did restoration

No I did not work with team anybody. Would have given my all to do so, but to start out we only had a local drag strip that was converted from one of the Air Force runways. By chance when I became interested in racing I came upon John Steen who had a small dealer network, Harry Tayler who did the R&D for Hodaka, and a few others of lesser known names. My first bits of advice was to change port timing untill the cranks broke and broke they did. If you wanted to go fast engines had to run more RPMs than the competitors so that is where I started. Yes Sir few can imagine how exciting it was to see your lane light come on first. Nope my engines did not last long very often. One of my last races was against a relatively new corvette with a very well built 454 and was sure he was going to walk away from me. At the eighth mile mark never heard him or saw him untill about a hundred feet from the line and there he was. He was quite put out to discover a bike worth about $1500 would eliminate him. After a few years I discovered that four stroke engines existed. Actually I had to keep my older pickups running because how else could I get to the tracks. Thanks