I'm looking forward to doing some magic on these heads!Thanks,Tom
Cool! Sorry, this is just exciting for me. Scottie
The rockers are going to be a challenge in these heads.Very small area to work with, so this probably leaves out alloy roller rockers, and will likely need steel roller rockers fabricated. Or maybe even non roller, just with some ratio on them.We are contemplating the options.
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.
What's your professional opinion Tom? For what I'm doing, am I better off with a turbo or a blower? What do you recommend? I guess I was always under the impression that turbos were more efficient at producing bigger numbers. Am I wrong about this?Scottie
Scottie,It's very difficult to make a blanket statement about that. They are both blowers. They do the same thing. They differ in the ways that they are driven. The turbo interferes with the exhaust stream, and the supercharger takes power off the crank. Both cause power drains in different ways, but the increases that they provide outweigh any losses by far. The biggest difference in noticeable behavior to the driver is the response lag that comes from the turbo. The turbo "lags" and the SC is instant response. Turbos are popular with road racers, but drag racers all use superchargers. There are pro's and con's. Size, location, and packaging can play big roles. Ability to fabricate a practical drive system can be an issue. You have to weigh all these things in the balance and decide what's best for the application.
Looks interesting, Scottie. Just one point, though - if you take a drive for the supercharger from the [redundant?] ignition drive, you will be relying on a very light timing chain and an even lighter duplex magneto / distributor drive chain, unless you plan to revamp this area of the motor. Also, any output to the blower will be at half the engine speed. If you can get a drive from the crank somehow, it can be more robust and you will be able to drive the blower at a greater choice of speeds and much faster if you need to. B.W.
The plan is to install a Bob Newby belt drive on this bike. Is it possible to order the belt drive with an additional V pulley off on the crank? I've had trouble trying to contact them, not sure if I have the wrong number or prefix or what. Scottie
This is where you start seeing what I have to go thru trying to get things done.Nobody makes anything we want, and nobody wants to make one-off things, unless they charge an arm and a leg, and takes a year.I have to deal with this all the time.
Ate you not keen on the idea of this blower Tom?
I'm not too worried about mounting the blower, Alex and I are both really good with custom fabrication. And if guys are bolting these blowers to Matchless and AJS bikes it can't be that hard. Also this seems to be the blower of choice for the Salt guys. Is using this blower as opposed to a turbo going to change anything on your end Tom? I don't want to make your job difficult but I do want to build some serious power and I feel that going with a blower we will be able to produce more power at lower RPMs.Scottie
It shouldn't make much difference to the head work.If you have a real lot of boost like a top fuel dragster, then we'd use a bigger exhaust valve. Basically, a good boosted head is a good n/a headYour cam guy is gonna need to know about it, though. I think there should be some movement happening on your heads next week or so at Mondello's.
Any news Tom?
I'll be going there tomorrow to see what's up.Please remember that there's only one guy doing all these heads for us over there.
OK. Just curious and excited. I know you've been busy with other projects.
Sounds Great! I know we discussed making some custom high lift steel rockers that could be adjustable through the top of the head which sounds like it might be the easiest way to go, but you're the professional. Also, I need to double check the rule book to see if that is an acceptable mod or not. I know the base line flow isn't very significant, but I am really curious what they do flow stock. And even more curious as to how much air we can really flow! I sent my heads to you because you seem to be the best in the biz, and you know things that I didn't even know existed. Scottie
News: We now have 38mm, 42mm, 45mm, 50mm, 55mm, 60mm, and 65mm throttle bodies to fit different size engines. Note, only 42mm throttle body has been customzied for certain bikes like Suzuki DR650. For other throttle bodies, you may need to do some mechanical adaptations.Note: for DR650, the motor is running better with a little rich AFR in some cases, like idle, and WOT.
Are you planning a single throttle body to feed both cylinders via a common manifold/plenum? Like a car?
Yes Tom, I plan on shifting between 6000-6500 RPMs. And 125hp at the crank is EXACTLY what I was hoping to achieve.ERC - I do in fact remember you saying that. Scottie
Nice job Scottie this is going to be a real project. Are you still feeling better with the new diet? ERC
129.937 mph is the record I'm trying to break.
Tom - Did you guys end up going with steel or titanium valves? Scottie J
I'm pretty sure that they are stainless steel. I will have to ask him to be sure, but I don't think that they would order titanium valves without asking me first.
BW - Is this the ignition I should be looking into? I never heard back from Debb @ Rex Caunt Racing so I sent another email this morning asking her to contact me this week.Racing 4-stroke, 36deg Crank Twin Battery Systemhttp://www.rexcauntracing.com/pages/misc_products.htmlIt looks like this system has a CDI box with electronic timing advance. That would be freaking sweet if this will work for my bike!Scottie J
http://www.c5ignitions.com/motorcycle-ignitions.htmlThis uses a similar system but pre programs it and provides a complete set of matched components. The best thing about this system is the ability to have multiple maps stored and flick between them with a switch, e.g. launch control with low rpm limiter, the with button push it then changes to normal use. The reason I liked it was that I can have a failsafe map, and use the others for testing and experimenting, I have the programming kit too.This uses power arc as the base system.
I'm not sure I get this C5. Looks like it is exactly the same as PA. The C5 install manual shows PA ignition in the photos. What do they offer that makes them better than PA? Also PA has upgraded with the M series units.