Sat down and had a nice talk with my engine guy last night. We decided that because we going to be boosting this motor after all, it is really unnecessary to spend almost $2000 on just pistons and rods alone going with custom 1-off CP pistons and Carrillo rods. Maybe on a future NA application/build, but like most garage builders, we need to get the most bang-for-the-buck that we can. So we decided that the forged Omega 8:1 performance pistons and billet rods from Hitchcock's will work just fine for this build. The pistons and rods are still a very robust design, but nearly half the cost of going with custom CP pistons and Carrillo rods. When all said and done, I will essentially have a 750 MK1 Interceptor with all the bells and whistles, plus the turbo charger, with a 90mm stroke as opposed to a 93mm stroke on an actual Interceptor. I also think I may have place that I might be able to Dyno tune the bike (a friend of a friend type deal).Tom - Are we looking at the first of the year before the heads will see the flow bench? No worries, just curious. Scottie
Impressive stuff Scottie !! This is going to be a kick ass bike - All the best !!Why a turbo and not a Supercharger setup ?
Therefor, for a smaller displacement motor, a turbo can build more HP faster. There is no "drag" on the motor with a turbo, and once a turbo spools, your HP is only limited to your tuning capabilities over the motor. This includes a combination of timing, (which is typically more retarded than a N/A motor), fuel mapping, boost controller and blow off valve. Also, another advantage to running a turbo over a blower is that with a turbo, because everything is tunable, I will be able to tune for more HP at lower RPMs and not put such a load/strain on the motor. I personally don't know much about tuning for a turbo, that's where my engine guy/friend comes into play. He's a Turbo Guru and is just as excited to build this bike as I am. What I can tell you is that we are shooting for 110HP at the rear wheel and this bike will be Dyno tuned and then broken in at the Drag Strip.Scottie
So its actually better to have a turbo setup for a low ( stock ) output engine to prevent the power losses to run the blower. I was thinking a supercharger may be better as the exhaust pulses may be intermittent and will result in the turbo taking longer to spool on a long stroke bike like the enfield. However, I am guessing this will not be of issue with a twin cyl Enfield cause of higher exhaust flow ( ??) . Also, is it true that for forced induction engines the porting ( less or minimal porting needed due to higher intake pressure) is done differently that the normal free to air type porting ( ACE ??) D
A twin will run a turbo. A single doesn't really do it well. A four would be better.Regarding the porting, actually for a turbo, the porting is done the same as normally aspirated for the intake. The exhaust might get a little more size than normal. The camming is very different with any type of forced induction. Porting for a supercharged drag racer would be larger in all ways. Supercharging moderately for the street could be ported the same as normally aspirated. Very application dependent things.