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Marshall Grice:

How much does a 2 stroke triple or twin weigh?

 i've scoured the internet looking for the engine weight any 2 stroke snowmobile engines.  the best I can find is a racing V4 engine that weighs 95lbs.  Is 95lbs typical of what a twin would weigh? 

Does anyone have any pic of the phantom or can tell me about his setup. I have took seveal pics of Bowlands and read about his engine and setup. I am in a planning stage of a build and just looking for info. Also does anyone use tunnels under the car or thought about using them.   Chad

Not sure about Amod but there are some Bmod cars using tunnels as well as front and rear diffusers. All the top CSR's/DSR's in road racing have moved to tunnels but I think the jury is still out on how worthwhile they may be for Solo.

The front splitter/diffusers and rear diffusers are not too bad as far as packaging (and the rear can certainly help work a rear wing), but packaging a set of tunnels for Solo may be more trouble than they are worth. I'm sure there are more qualified opinions available here than this one!

---

Joe Gonzalez
1979 Legrand DSR- B Mod
Gilbertsville, NY

Please share any info about the Shark engine and set-up. The Vancouver Special has tunnels, the Phantom does not: http://s221.photobucket.com/albums/dd280/Bailor_AM_Special/competitor%20cars/

Marlin

I read bowland's info on here awhile back. Can't find it now though. I think the phantom posted it.

I would have to agree with all I've read here so far except that noise may actually NOT be a tougher problem to conquer with 2-strokes (if you know what you are doing).

All it takes is sound engineering (pun intended). I worked as a noise cancellation engineer many years ago.

Since a 2-stroke must run at a fairly constant RPM (hence limited range of noise frequencies) with the associated CVT, it makes designing/tuning a sound cancellation system easier. 

Modern 2-strokes in sleds are extremely quiet and some racing sanctioning bodies that have modified 2-stroke classes run more strict noise limits than any SCCA event.

In either 2 or 4 stoke cases, it generally takes big mufflers to get the noise down w/out losing HP. 

Keeping the pipes out of the breeze helps a lot since the pipe/expansion chamber sheet metal sides are nice loudspeakers. They must be wrapped if they stand out. Same for inlet tract. 

Perhaps the quietest and greatest power for the least weight would be a turbocharged 2-stroke running at constant RPM with a CVT. 

A turbo 4 stoke with 4 or 5 valves per cyl might be quieter still with a CVT-but one would have to work at the weight a little more.

 Last, big HP with the Japanese cars in drag racing is somtimes still only made by carbs on some motors. Carbs can do atomizing that injection still cannot match on some inlet tracts.  Fexibility probably always will still belong to injection.

I've always wondered way no one has asked for more wing for heavier cars in AM.

Could make the class more fun for more different kinds of cars-perhps less expensive ones to build, too.

The argument that wing area should be restricted to limit the overturning moment is not valid if the vehicle weight down below in the chasis is increased also.  Maybe extra wing area could also be tied to a rule to drop the max wing height at the same time to be doubly sure of no ncreaded danger..

 Ahhhh, who am I kidding? Somebody would gripe and kill the whole idea. 

AM is not a growth oriented class especially so now that it doesn't have any min participation numbers as the 2nd fastest SCCA solo class (next to F125) :->

 

 

 

 

Marshall Grice:

Marshall Grice:

How much does a 2 stroke triple or twin weigh?

 i've scoured the internet looking for the engine weight any 2 stroke snowmobile engines.  the best I can find is a racing V4 engine that weighs 95lbs.  Is 95lbs typical of what a twin would weigh? 

 

Depends, a state of the art 700cc injected twin Suzuki/Artic Cat weighs 85 lbs with all accesories.

Stock flywheel/mag and all injection.

There are about 4 different big bore 900cc kits for these and I do not believe they add more than a few lbs total. That the DSR cc limit.

Bigger bores than 900cc my be available.

The older Rotax triple at 800-900cc with mods is generally about 98 lbs. Very light for having 3 cycl construction. Definitely more peak HP-but one has slightly more finicky clutch tuning at 9500 vs 8000 for atwin. That sometimes can erode some of the HP delta of the better breathing motors with more cylinders if you don't get it right.

 

The recently introduced 1000cc twin replacement for the f7 Firecat mentioned above from Suzuki is heavier and bigger dimensionaly (add about12 pounds and 1 or 2" length)

So, one can do  DSR or FS car  for BM at 900cc with about  125lb total for CVT motor and shafts. About 177 to 185 HP at motor. A triple would add pehaps as much as 15 HP-but weight is close to MC descibed below then. The boxer  or V 4 cylinder racing 2 srokes are an unknown. They  apparantly ont come tuned for max HP and may not work with CVT's well in rapid on/off solo situations. Also chassis packaging is much different.

The 900cc big bore kitted Suzuki 2-stroke F7 700cc twin  is lighter with CVT and shafts  than the lightest state of the art performance 1000cc Suzuki 4 stroke MC with built in  tranny by about 15 lbs still.  But 4 stoke has lots more HP at motor shaft over probably all twin 900cc 2-strokes. 2-stroke triple is closer to 4 stroke 4 cylinder in HP. 4 cyl 2-stroke may match 4 cyl 4 stroke in HP.

If one adds the questionable dryump to that 4-stroke- add another 15+ lbs to the delta. The many qts of oil in a remote can is where a large portion of that addional weight is.

 

BTW, Direct injection and running alcohol are other tools for more HP w/out adding weight on both 2 or 4 strokes.

Orbital in OZ may hae some nice stuff too.