Author Topic: Supercharging with a Drouin (Read 9738 times)

jonbuoy · « **on:** February 11, 2009, 04:58:44 AM »

Trying to put a budget together for supercharging my 750, I've seen a Drouin charger but what else will I need? So far I have on the list:

Dyna 2000 ignition I have a Dyna S but I'm figuring the programmable 2000 will pay for itself on "dyno" day.
Stronger rods - Cycle X?
New Primaries + tensioners
Cam chain (tensioners already almost new)
All new valves + 3 way valve job
Main bearing shells
Heavy duty studs
Heavy duty clutch springs + new standard plates

The other items I'm unsure of are:

A: Porting work - how much difference will this make on forced feed?
B: Softer than street cam?
C: 836cc with lowered compression (and a bigger base gasket or machined pistons?) or "standard" oversize pistons?

I know a supercharger has its disadvantages but for trickness and the sound I think its worth it. Is there anything else I've forgotten about/to be aware of?? I'm not planning to drag the bike, I'll keep the boost at a moderate usable street level. Max when new was around 10 psi +.

Duke McDukiedook · « **Reply #1 on:** February 11, 2009, 01:39:33 PM »

I have no idea how to help you but please put this on the build forum when you pull the trigger on the build. Maybe Nitro hunter or someone else with drag experience can help you?

NitroHunter · « **Reply #2 on:** February 11, 2009, 08:06:58 PM »

Blowers (on ANYTHING) are bad-to-the-bone COOL!
Regardless of this motor's size, use forged flat top pistons, and don't scrimp on the wrist pins. The 15mm pins are anemic at best, so use good ones.

Go online and play with a compression calculator, some of the turbo sights have them. You can figure what your actual boosted CR will be by varying static CR & boost pressure.
Unless you never intend to be far from home, you will be at the mercy of 91 octane gasoline.

An undercut tranny is always good, motors under boost tend to gain RPM surprisingly quick when it pops out of gear...

jonbuoy · « **Reply #3 on:** February 12, 2009, 08:53:34 AM »

Thanks guys, the estimated build costs are climbing rapidly

I am really keen to do a supercharger but not sure if my CB750 is the best bike for it. If I'm investing a lot of money I can't help thinking something a little more modern wouldn't be a better option. I love the idea of a retro blown motor though $:-\$

NitroHunter · « **Reply #4 on:** February 12, 2009, 10:09:33 AM »

Old school is cool!
Don't mean to scare you away from doing a blown SOHC, just be aware of potential issues with any pressurised engines. 'Engine strength' needed is really dependent on your boost level AND proper tuning.
Research old articles on the internet and the Dragbike.com website, definitely spend the time to find out what other guys have done for street applications. It may take some looking, but do your homework and you'll get better grades.

I can tell you from experience that more boost = more adrenalin rush. Plan accordingly!

jonbuoy · « **Reply #5 on:** February 12, 2009, 11:29:24 AM »

Its a good idea for me to know how much its going to cost me - the blower itself isn't exactly cheap and I don't even know what issues it might have of its own. Thats my main concern, the setting up and making it work is all part of the building fun. It makes sense to do the right thing and beef up the engine - I have a complete spare set of engine internals, barrels and a head. The cowboy bike builder part of me is thinking that I could run on a conservative boost with my motor completely stock until the inevitable "bang" happens, as long as it doesn't happen on a wet corner

The other part of me is thinking I should do it right and tune for maximum smoke

jonbuoy · « **Reply #6 on:** February 12, 2009, 11:30:23 AM »

A third part of me is saying - hey you could buy a sports touring bike with that kind of money

SOHC4 Cafe Racer Fan · « **Reply #7 on:** February 12, 2009, 01:00:35 PM »

Try calling or emailing Chris Redpath at MotoGP Werks (a fellow Kiwi), who helped Carpy mate a Drouin supercharger to his CB750K0 show bike, the Koppa Kafe (http://www.cb750cafe.com/bikes.php?cat=1&id=59). Chris is an incredibly knowledgeable and helpful guy.

MotoGP Werks:
(714) 633-3855 (Note: located in Orange, California USA -- PST)
motogpwerks@yahoo.com

jonbuoy · « **Reply #8 on:** February 12, 2009, 01:10:42 PM »

Hey thanks for the link! he he that Carpys a character eh?

NitroHunter · « **Reply #9 on:** February 12, 2009, 08:11:24 PM »

OMG love that speedo! You guys gota look.

754 · « **Reply #10 on:** February 12, 2009, 08:18:28 PM »

Keep in mind the Drouin never got great reviews even while they were still making them.. It would be one of my last choices.

..unless its real reasonable..

You can get a Rotrex for around 2500, that is way more efficient..

NitroHunter · « **Reply #11 on:** February 12, 2009, 08:25:48 PM »

Frank,
Do you remember seeing the blown Harley around Seattle area bike shows (Clark Marshall's show) with the license plate that read '200 hp'? I worked at Todd ship yard with the guy.
BLOWERS ARE WAY COOL!
I'd trade my turbo in a heart beat for a blower!

jonbuoy · « **Reply #12 on:** February 12, 2009, 08:37:14 PM »

The Drouin looks like its a complete kit already to go - my problem with a rotrex for a 750 is making a plenum chamber and mounts/tensioner etc without any machine tools/lathe. TTS in UK look like they do reasonably priced kits for Blades/R1/GSXR - if only they did a kit for a VMAX

754 · « **Reply #13 on:** February 12, 2009, 08:48:36 PM »

Not sure about that 200 HP bike, If I saw a pic it might jog the memory.. did it have white pipes?

A buddy has run a Rotrex on 2 bikes, set every thing up from scratch. He is trying a new type type, forget the name.

My fave was the Magnacharger, Fageol is a reasonable substitute, but the more I talk to the Rotrex user, the more the increased edfficency appeals to me, and the old ones if you can find them are still fairly close on pricing and they are old and used.

If you used multi-rib belts the drives are easy to make and change ratios.. can be done on a very small lathe, for low cost..

NitroHunter · « **Reply #14 on:** February 12, 2009, 09:08:09 PM »

No question the blower fab work is, well, a labor of love.
But I'd still rather have the gawking of real blower guys, asking questions because they can see a belt drive, rather than a wild 4 into 1 header leading into my turbo...
It's just cooler.
When I shopped for the turbo, it just wasn't on the internet - no, wait, - there was no internet when I bought the turbo...
That withstanding, blowers just look cooler no matter who built them.
Of course I'd prefer a screw type...

jonbuoy · « **Reply #15 on:** February 14, 2009, 08:19:22 AM »

For some reason a turbo charger doesn't have the mechanical wow factor that a supercharger does. Good link here on a guy who made his own plenum for less than a couple hundred dollars.

http://www.galantvr4.org/ubbthreads/showflat.php?Board=UBB11&Number=554229&page=0&fpart=1

754 · « **Reply #16 on:** February 14, 2009, 08:30:14 AM »

Usually the Blowers on 750CB are driven off the dyno end of the crank, But Magnussen started to drive them off the klutch on Kawis (not sure if that is easy to do on a 750).

At any rate, I think building the drive, is not super difficult.

I also have been thinking it may be possible on a kickstart bike to maybe seal off the dyno side end of crankcase. This would allow the drive to be placed between the rotor and the engine case, if the dyon can be run dry. It involves a thin seal plate, that would be tapped into the enginge case on main bearing web, and blocking off the oil return holes.

Ricky_Racer · « **Reply #17 on:** February 14, 2009, 10:00:13 AM »

754, with little info available, my research has indicated that Jerry Magnusen drove his blowers off the clutch, whereas Russ Collins (in at least one instance) drove his off the dyna side with a block-off plate.

I've had no luck finding any info or diagrams of the Magnusen clutch drive components.

The only issue I see in driving a Rootes-type off the dyna using a Drouin-type crank extension while retaining the stock dyno, is the angle from the blower outlet to the CB750 intakes. I believe this issue can be solved with curved intake runners.

I've tried uploading pics but the site won't take them for some reason today.

I'll try later. RR

754 · « **Reply #18 on:** February 14, 2009, 10:09:42 AM »

blower can be located anywhere, you use an extension shaft to get to the drive pulley.

Ricky_Racer · « **Reply #19 on:** February 14, 2009, 10:34:38 AM »

Won't that require an extended snout on the blower? RR

754 · « **Reply #20 on:** February 14, 2009, 11:15:20 AM »

yes, you can use a longer snout, or a coupled extension, or a jackshaft. Not an obstacle that cant be overcome..

The first Mangnachargers for HD, used a drive pully on the left side of engine, with blower on the right. It had a belt running up the front of the frame, then a shaft across, then a 90 deg drive.

jonbuoy · « **Reply #21 on:** February 14, 2009, 01:20:29 PM »

The guy selling the charger has been very helpfull - he sent me some extra pictures. The nail in the coffin for this one is that I can buy a brand new bolt on supercharger kit for a ducati monster for only a couple of hundred more than the Druin would cost me.

jonbuoy · « **Reply #22 on:** February 14, 2009, 01:24:11 PM »

pics....

jonbuoy · « **Reply #23 on:** February 14, 2009, 01:25:59 PM »

more...

jonbuoy · « **Reply #24 on:** February 14, 2009, 01:27:21 PM »

last ones

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Author Topic: Supercharging with a Drouin (Read 9738 times)