EFE with two intake cams

[Blower1]

Has anybody ever try to put two intake cams on EFE?

Intake have 8 degrees more opening time and 0,5 mm more lift than exhaust cam.

I have think to try this in my supercharged EFE.

I know that some turbo Hayabusa owners has used two original intake cams with good results.

One my friend, who have GSX 1400 with turbo got about 50 rwhp more by just swapping exhaust cam to intake cam.

His cams were dialed in 110/110 and boost remains the same as before cam change.

On GSX 1400 intake cam have 16 degrees more opening time and 1,5 mm more lift than exhaust cam.

 

 

 

[Poldark]

I have never build a forced induction engine, but what I have read is that getting exhaust gas out of the engine is the challenge.  On a naturally aspirated engines, the duration overlap between intake and exhaust is critical to provide scavenging effect.  Your supercharger will be pushing in plenty of air.  I also recall reading about supercharged car engines with the exhaust valve seats enlarged to use intake valves.  Someone with actual experience should be able to tell you more. 

[Gixer1460]

Can't say about a mechanical supercharger but Sean @ Big CC  did do a EFE head with equal sized valves in both inlet and exhausts following the above thinking and only did it once which speaks volumes ! It was an absolute dog for building boost - turbo obvs. Whether it would assist a mech. blown motor is anyone's guess but over the 100 or so years that the IC engine has been tuned and raced, no one it would seem, has made significant advantage by using oversize exhausts or using cams with equal lifts? The usual problem with any blown engine is obtaining suitable lift with minimal duration and overlap whilst not smashing the valve train to bits!

[Blower1]

11 hours ago, Gixer1460 said:

Can't say about a mechanical supercharger but Sean @ Big CC  did do a EFE head with equal sized valves in both inlet and exhausts following the above thinking and only did it once which speaks volumes ! It was an absolute dog for building boost - turbo obvs. Whether it would assist a mech. blown motor is anyone's guess but over the 100 or so years that the IC engine has been tuned and raced, no one it would seem, has made significant advantage by using oversize exhausts or using cams with equal lifts? The usual problem with any blown engine is obtaining suitable lift with minimal duration and overlap whilst not smashing the valve train to bits!

Most of the aftermarket camshafts for supercharged engines have more lift and duration on exhaust than intake.

I would like to know if anybody has tested intake cam on the exhaust side of non boosted EFE engine?

[Duckndive]

Dont the busa brigade  use two inlets or exhaust cams as cheap performance boost ? Seem to recall seeing it on the old 200mph forum 

[Blower1]

I compared intake cam to exhaust cam. Lobe profiles looks like mirror images to each other.

[Blower1]

I swop the exhaust cam to intake cam. I rotate the cam sprocket 180 degrees. Now there are 21 cam chain pins between markings.

Cam lobe centers are now: in 111 and ex 112.

I will take bike to dyno in the spring time to see if more exhaust lift & duration have any effect on power.

[Blower1]

I took valve lifts every 10 degrees and made picture with autocad.

Blue is intake valve opening time, cyan is original exhaust and red is intake cam on exhaust.

There are quite big differences on exhaust valve openings. With intake cam the exhaust valve opens more agressively.