Turbo or supercharged 2Ts?

[husaberg]

lol kind of had your look (-: nasty me

Yeah yeah I am black and smart.........

[TZ350]

The proposed change to allow super/turbo charged 2T's

Write to MNZ to have your say.

http://www.mnz.co.nz/docs/default-source/regulations/2015-summary-of-all-proposed-rule-changes-for-websitea97dfb456e51694ab575ff0000938921.pdf?sfvrsn =2

The proposed change is on Page 5

[F5 Dave]

So 70cc? That still feels like 38hp minus some losses is still quite a lot.

[koba]

I haven't got past giggling about this bit yet:

22.3.1a – When the riders have lined up on the grid they are deemed to be under the starters control at the instant the RED FAG reaches the side of the track. Any motorcycle that moves in a forward motion whilst under the starters control shall be deemed a jump start. Starters control ends once the event commences as per Rules 6.6.1 and 6.6.2.

[koba]

So 70cc? That still feels like 38hp minus some losses is still quite a lot.

Yeah, 70 sounds quite large.
I'm guessing the logic is giving N/A Engines 1.5 times the capacity, same as the 4 strokes, plus a wee bit of rounding...?

[TZ350]

So 70cc? That still feels like 38hp minus some losses is still quite a lot.

I am not sure what is possible or even if someone would bother or could make it mechanically reliable enough but I thought 2T's deserved the option as 4T's have it and it is also an interesting area and some of the attraction of buckets is the chance to be innovative.

And if you think about it, from a commercial point of view, a forced induction 2T with direct fuel injection could be a very handy sort of engine. Cheap to make, light weight, clean burning, fuel efficient, very good performance, lots of sporting, commuting and small vehicle applications for an engine like that.

Yeah, 70 sounds quite large. I'm guessing the logic is giving N/A Engines 1.5 times the capacity, same as the 4 strokes, plus a wee bit of rounding...?

Yes NA 1.5 X Supercharged 70's

There is some question on the net about whether forced induction on a crankcase scavenged 2T will work anyway. And if it did, the thinking seems to be that there will be natural limitations on usable boost and power increases that are possible, and for sure, because of blow through the pressure power relationship will not behave like it does with a 4T.

I don't know about any of that but Buckets is a great place for the mechanically adventurous to find out.

I am not sure what a sensible size is either, but the way I figured it, the supercharged 4T limit of 100cc is 2/3rds the normally aspirated 4T. So 2/3rds of 125 is 82.5, but there is talk of MX85's so I chose a 70cc limit for 2T forced induction.

My thinking on capacity was 70cc because that allowed room for the possibility of NA 85cc MX engines to fit in between the forced induction 70's and the water cooled 100's and air cooled 125's.

And from a practical point of view, 70cc is a common big bore kit size for a lot of 50cc bikes and scooters.

I think allowing a forced induction option for 2T's is fair enough, its just the capacity that is the question.

[F5 Dave]

What about 50cc. 50cc is a common size for fifties. If it ends up not being enough then try the big bore, but it's hard to go back. Look what happened to F3 with SV650s.

[speedpro]

There is some question on the net about whether forced induction on a crankcase scavenged 2T will work anyway.

You only have to look at the turbo snowmobiles in Canada - turbo, direct injected, and LOTS of horsepower.

[TZ350]

What about 50cc. 50cc is a common size for fifties. If it ends up not being enough then try the big bore, but it's hard to go back. Look what happened to F3 with SV650s.

I thought 70cc, but good point, please put 50cc capacity forward in a submission to MNZ on the proposal, better to have 50cc or maybe 60-65cc than nothing.

[TZ350]

You only have to look at the turbo snowmobiles in Canada - turbo, direct injected, and LOTS of horsepower.

Does anyone have actual numbers and or back to back dyno graphs, I am sure it works, but how well????

[F5 Dave]

I'd rather progress 107cc so I didn't have to do crazy destroking, but I got over it.

[Yow Ling]

Does anyone have actual numbers and or back to back dyno graphs, I am sure it works, but how well????

Post 28 has a 50cc AM6 making 19hp

[TZ350]

Post 28 has a 50cc AM6 making 19hp

Thanks

Ok so 50cc + Turbo = 19hp then 70cc might be 70/50*19 = 26.6hp much the same as other developed 2T's.

So in this example at least, 70cc looks about right for the capacity.

Here's one to wet your appetite TZ

[TZ350]

A 50cc 2t turbocharged engine based on an AM6 as used in the aprilia RS50, running methanol and close to 20 psig boost. (1.4 bar)



http://www.motorcycle-usa.com/287/15...reamliner.aspx

50cc and 24hp on Nitrus Oxide but mechanically unreliable. Turbo worked better from a reliability point of view.

You can pretty much bet that this motor is as developed as your likely to get.

So 70/50*24 = 33.6hp for 70cc (assuming the Turbo didn't make more power than the Nitrus)

Looks like for 70cc 33.6hp is going to be pretty much the upper limit, now thats not to frightening.



Been close to that already with the air cooled Suzuki GP125.

From what I can see, 70cc for turbo 2T's still looks about right.

[F5 Dave]

That's probably 6hp more than any bucket has hit the track with. You should have seen how Kels 29hp, read 26 by lap 3, pulled away from everything at the GP. Oh wait. You did.