G'day All,

I have been thinking... as much as I love the idea of supercharging... a nuts N/A mini sounds much more attractive to me. Less parts the better I reckon.

What are people's thoughts on say an 1098cc with the 7 port crossflow head, higher compression and twin 1.1/4 SU's with a high flowing exhaust vs the s/c'd 1098cc.

Do you think the N/A config above would fair well against the S/C'd?

Cheers all.

Josh.

Really bad idea there if you ask me. You've got four intake ports, why choke them with two small SU's?

If you must have SU's you'd need 4x HS4's or 6's, but just about everyone else with that head will inject or run Weber, Dellorto or bike carbs.

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Simon

The adventures of an owner builder in the Tallarook Ranges

So maybe twin webers?

Absolutely, twice the noise

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Simon

The adventures of an owner builder in the Tallarook Ranges

So ya reckon a high comp, crossflow, twin weber'd 1098cc would fair well against an s/c'd 1098cc?

I really wanna avoid s/c'ing... i just don't like the idea of adding more maintenance to something that already requires a fair bit of maintenance.

I've never done either (someone who has can make comment here) but instinctively I'd say the N/A crossflow setup would make the same ballpark power as a supercharged 5-port 1098 (at modest boost) but would be more reliable, economical and tractable into the bargain.

I reckon it'd sound better too

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Simon

The adventures of an owner builder in the Tallarook Ranges

That's what I was thinking. More reliability (apart from the carbs falling out of sync) hopefully somewhat cheaper but definitly an AWESOME noise... would sound insane.

Hi Simon,

I'm only gana say one thing and then I'll run away... Your assuming that its running at 100% volumetirc efficiency...

I personally would asses what the requirements of the motor are first (its pumping abilities) so you'll need to know what comp and cam your running (for a start, and you should also consider what kind of engine speeds it will be doing most of the time)...

Having said that... I'd go 2x 40 dcoes for a starting point

nothing like the noise of a screeming webbers!!!

ok thats all from me I'm running away now

As with anything like this is back to the old equations

Money VS Commitment VS Torque VS Horsepower

If you've got the commitment but no money its just torque



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There's lots of assumptions so far

Whatever else is on the motor though, I still say 2x 1-1/4" SUs is too little carb for a nice 7-port head

Besides, who could go past the opportunity of twin Webers!?

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Simon

The adventures of an owner builder in the Tallarook Ranges

4 x 1¼" SUs

That'd be fun too, I'd love to see it done

Hell of a job balancing them though

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Simon

The adventures of an owner builder in the Tallarook Ranges

i'm sure i'll end up cam'ing it... not sure what cam to go tho... my mate works for Wade... you guys got a suggestion profile wise?

Wade ? Wade 104 Cam

http://reality.sgiweb.org/mg/ahsdc/goblins/tech/wade.htm



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Yeah,,,, I can only think of two things better than the sound of webbers,,, neither of which I'm allowd to write...

You are right,, but all I was getting at is that an 1098 has 67 cubes divide by 4 = 16.75. So each cylinder can holds 16.75 cubes. So each of the 1 1/4 would need to flow enough air to fill 33.5 cubes per cylce. For every day driving your average engine speed is around (ok I'm pulling this number out of my bum) 3200rpm. So if it could flow at 100% vol eff the most it could use is 214,400 cubes divide by 2 = 107,200..

So at 3200rpm each carb only needs to move 107,200cubic inches or 62 cubic feet a min. I reckon ( don't have a flow bench so can't say for certain) that a single 1 1/4 can do that.....
.... but thats assuming you have 100% vol eff... there is no way you would...

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.BUT who drives like that much of a saint anyway... thats why I say go the webbers!!!!!

(Ok now I wait to be corrected by some who DID go to skool and DOES have a flow bench )