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Re: [turbobike] cam settings

John C Williamson (john.williamson5@virgin.net)
Fri, 7 May 1999 19:03:19 +0100

The only real way to find out is to try it but:

Best cam timing would be one that helps the exhaust out easier and while
there is still some pressure in the bore to help it, which will in turn help
drive the turbo.. (and make more noise..)
Try advancing the exhaust cam a few degrees, this opens the exhaust valve
earlier, so less use is made of the pressure in the bore to make power
directly, but more energy is there in the gas to drive the turbo. This
should make more boost at lower rpm, and make it easier to get rid of 250+
bhp worth of exhaust gas through a hole(s) that was meant for 120.
The inlet cam is not a problem and usually best left alone, due to the fact
that it is getting forced in under pressure, and twice the pressure equals
twice the flow (in theory!). Bear in mind that lowering the compression
ratio also hinders the ability of the engine to 'push out' the exhaust gas
(and draw in the inlet charge, but this does not matter much if you have
2bar boost...).

As for leaving the line - every bike / rider / setup / strip is different.
It mainly depends on if you hold your mouth right and how angry you are.


My Dyno Site:
My Small Gasturbines and other small jet engines site:

----- Original Message -----
From: <GSXRTurbo1@aol.com>
To: <turbobike@natvideo.com>
Sent: 07 May 1999 17:08
Subject: [turbobike] cam settings

>   As mentioned in a previous e-mail, I have an '86 GSXR1100 Mr. Turbo draw
> through system with a Mikuni HSR42 carb. I am using the stock cams, and
> wondering what the best settings (cam centerline) would be for this
> application. Anyone have experience in this area? What would be an approx
> to leave the starting line at the dragstrip with no wheelie bar, and what
> would be the best technique for the same? Thank you in anticipation of
> answer(s) - Thomas Gafa