Forced induction 100cc

[husaberg]

[Sketchy_Racer]

Well, still no improvments, got 6.8hp on my dyno. (that would be around 7.5hp on a dyno jet) But then the fuel pump gave up. I pulled it apart but seems it's done its dash. It's been sitting in the trailer for over 6 months and its got water inside it.

I've got a pump off of a 600 here that will do. I also need to consider getting a adjustable pressure regulator to offset the boost pressure so the little pump from ecotrons might not have been up to it.

Seems that with the pitbike motor high HP levels are right out the door, at the point where I wonder if I keep wasting time with it or look elsewhere.

[Drew]

Well, still no improvments, got 6.8hp on my dyno. (that would be around 7.5hp on a dyno jet) But then the fuel pump gave up. I pulled it apart but seems it's done its dash. It's been sitting in the trailer for over 6 months and its got water inside it.

I've got a pump off of a 600 here that will do. I also need to consider getting a adjustable pressure regulator to offset the boost pressure so the little pump from ecotrons might not have been up to it.

Seems that with the pitbike motor high HP levels are right out the door, at the point where I wonder if I keep wasting time with it or look elsewhere.

Got a GL 145 here. Tell ya what, you super charge it to satisfy your testing, then do it again on something you're allowed to run.

[mr bucketracer]

Well, still no improvments, got 6.8hp on my dyno. (that would be around 7.5hp on a dyno jet) But then the fuel pump gave up. I pulled it apart but seems it's done its dash. It's been sitting in the trailer for over 6 months and its got water inside it.

I've got a pump off of a 600 here that will do. I also need to consider getting a adjustable pressure regulator to offset the boost pressure so the little pump from ecotrons might not have been up to it.

Seems that with the pitbike motor high HP levels are right out the door, at the point where I wonder if I keep wasting time with it or look elsewhere.

what does a standard fxr 150 put out on your dyno? on a dyno jet its 14.3 to 14.5

[quallman1234]

what does a standard fxr 150 put out on your dyno? on a dyno jet its 14.3 to 14.5

Hopefully less than 13hp. As thats what mine barely makes, mines got a exhaust/carb and some awfully crap porting.

Will put my mates one back on there again at some stage. Standard carb, just a underseat exhaust and jetted for no airbox. So pretty much stock.

[TZ350]

what does a standard fxr 150 put out on your dyno? on a dyno jet its 14.3 to 14.5

Yes std FXR150 14.5 ish on a Dyno Jet ... I would not try hotting up your engine, for my money I would lower the compression and retard the spark, 10 static + 10 advance and just keep adding pressure. Supercharged engines run best on low compression (6:1 ish) standard or less than standard cams with minimal or best yet no overlap. Anyway for what its worth, back in the day that is how I remember them being setup at work.

[pete376403]

Yes std FXR150 14.5 ish on a Dyno Jet ... I would not try hotting up your engine, for my money I would lower the compression and retard the spark, 10 static + 10 advance and just keep adding pressure. Supercharged engines run best on low compression (6:1 ish) standard or less than standard cams with minimal or best yet no overlap. Anyway for what its worth, back in the day that is how I remember them being setup at work.

The volume of air delivered by the super / turbo charger is more useful then boost pressure. ie more air available = more fuel burned = (hopefully) more power.
Although, I've never done anything with mechanically supercharged engines, only turbocharged.

[Grumph]

when i did the Roots blown F3 500 kawa twin, we ran 9:1 on methanol. The guy whose rolling road we used had a mate who was building Penskes Cosworth turbos at the time. We sent him the details of bore,cams, valve sizes etc and he came back and said, you're on the right track. made around 110 at the wheel with 15lb boost.
Now this was a 74mm bore with big squish areas...with the little 2 valver your problem is the chamber shape and getting it to burn.
Not a lot you can do without playing with crown shapes - on forged pistons...

A good look at the budget may suggest starting with something more suitable.

[TZ350]

Again this is only as I remember it from way back when .... but I would not be worried about the four speed gearbox, because a positive displacement supercharger provides a massive torque increase everywhere and at any rpm. So the engine will pull like a tractor from low down and rev right out. Even on a mild cam it will rev till the valves bounce.

But I would be worried about the engines cooling. The little motors air cooling might be adequate for 7-10hp but with the supercharger you will need to be shedding double or triple that. Water methanol (or acetone so as to stay legal) injection might be the go. And maybe a big oil cooler and supplementary electric pump to shift a lot of extra engine oil through the radiator.

I think it can be done, its a very interesting project and am a little jealous.....

[Sketchy_Racer]

Yeah it's a interesting project for sure, with a load of hurdles to get over with the pitbike motor.

I think I will carry on with the pitbike motor, purely for the fact that I have it and it will be interesting to see what gains I can make with it.

I'll have a look around for a 3valve head for it, Im just not sure if they will fit into the 100cc bore.

Next job is to pull the motor out of the frame and improve the engine mounts as well as make the supercharger cradle and tensioner.

[Brian d marge]

You will have trouble with crankcase flex and head stud stretch
This and some ther stuff will limit how much you can shove into the motor
Stephen

But it needs to be done

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[TZ350]

You will have trouble with crankcase flex and head stud stretch

I do remember the methanol engines on the dyno. They had the water galleries between the block and head plugged, the water was feed by a hose from the back of the block to the back of the head. no head gasket, but Copper "O" rings around the bores and heavy studs, steel backs on the main bearing caps. Under full boost you could see the fumes jetting out from the head/block joint. Steam from the water boiling in the brake. And the noise from the exhaust, induction roar, scream of slipping drive belts, all like a mad women possessed at 9,000 rpm......... so exciting, wet my pants when the BDA snapped a cam.

[Grumph]

Yeah, our limiting factor in the end was the head walking on the barrel. i really should have dry decked it but the owner called enough...

If you do find a 3 valve head, use the 2 valve side for exhaust and the single for inlet. reverse of naturally aspirated applies - easy to get the mixture in so only one inlet needed but the smaller twin exhausts will stay cooler. To encourage cooling, use a lot of overlap. i know it's not popular due to perceptions of lost boost but the extra flow through the valves at overlap provides a welcome cooling effect.

With full house unblown cams on the blown motor the torque was unbelievable. After we got it percolating properly, I seriously considered pulling gears out of the box - six speeds was hard work, three would have been perfect. BTW the cams were the same as Tony McMurdo's winning pink Kawa - a shitload of overlap.

toluene is your friend in the fuel.....

[speedpro]

I dry decked my Z1 turbo by fitting external oil lines to the head. Even with HD studs, steel orings, and coated copper head gaskets it was difficult to get the head gasket to seal. We sprung a small oil leak in the starter motor area at Taupo once when we were pissing round with 19lbs boost on an 1166cc motor. When I pulled it down it had a crack in the #2 mainbearing cap part of the lower crankcase. The crack extended to the outside which is where the oil was coming from. Had it welded and I hand filed it back to size. If the motor is a bit "budget" it is going to try and pull itself apart. You might want to machine up some sort of girdle top and bottom with HD studs between to keep it together tight. I used stock Z1 cams degreed with a bit more overlap. Cooling was a big problem. Standard unleaded pumpgas has about 30% toluene so that and some methanol with acetone to blend should be good.

[Brian d marge]

The cooling comes from the change of phase from a liquid to a gas and the mire you can get that to happen in the squish flame front area the more stable the combustion and the higher pressures you can run
Apart from beefing up crankcases and studs waste heat transfer one method of reducing head walk was to have a raised lip around the bore lapped into a groove around the head combustion chamber ,. Cant think of the name applied to this method .dry no gasket and as smooth and as flat as u can get it
Possible on a 4cyl easy on me single enfield hahahaha

Stephen

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