Silvertop velocity stacks - trumpets?

[Chrisso]

There are inherent issues with running unequal lenght trumpets as this may cause unequal air/fuel ratios in different cylinders. Slightly shaved might not make much difference, but if you had a 45mm on the last cylinder, and 60mm on the other 3 this could cause major issues!

[jondee86]

Chrisso Wrote:There are inherent issues with running unequal lenght trumpets as this may cause unequal air/fuel ratios in different cylinders. Slightly shaved might not make much difference, but if you had a 45mm on the last cylinder, and 60mm on the other 3 this could cause major issues!

Maybe... maybe not Some motorcycles run two longer and two shorter
trumpets. The theory is that by having the ram effect happen at different
rpm's, the torque peak becomes wider and lower. Makes for a broader
power band.

Cheers... jondee86

[Jan Pedersen]

jondee86 Wrote:

Chrisso Wrote:There are inherent issues with running unequal lenght trumpets as this may cause unequal air/fuel ratios in different cylinders. Slightly shaved might not make much difference, but if you had a 45mm on the last cylinder, and 60mm on the other 3 this could cause major issues!

Maybe... maybe not Some motorcycles run two longer and two shorter
trumpets. The theory is that by having the ram effect happen at different
rpm's, the torque peak becomes wider and lower. Makes for a broader
power band.

Cheers... jondee86

I saw that on a formula Atlantic 4AG and wondered why... Maybe I should try it out

[cue]

Chrisso Wrote:There are inherent issues with running unequal lenght trumpets as this may cause unequal air/fuel ratios in different cylinders. Slightly shaved might not make much difference, but if you had a 45mm on the last cylinder, and 60mm on the other 3 this could cause major issues!

The trumpets all were same size & length, but only just slightly shaven, cut at the end to dodge the brake booster. This is how the car came from Japan. Already built up, fully loaded, with 20V blacktop and Trottle trumpets. Unfortunately i dont have a picture, as i did but lost it due to transfering all pictures to my new harddrive, and the harddrive was corrupted.

Also i sold car to someone down in Wales (G.B.) otherside of the country, he was going to use it for rallying. so cant really get any new pictures.

[jondee86]

There are plenty of pictures on the internet that show trumpets with
the rear one cut to avoid contact with the brake booster. Right now I
am getting some curved trumpets made for the same reason.

However, I don't think that trimming the trumpet bellmouth on one
side is a big deal. Some tuners use large diameter bellmouths and
trim both sides where they butt together. Sure, there will be some
difference in flow between the best and the worst trumpet, but I have
never seen any figures to show the percentage.

My gut feeling is that the benefits of having the trumpets, far outweighs
any small variations in cylinder filling.

Cheers... jondee86

[Nomuken]

Recieved mine from tokyoseven, fast delivery, so I now can recommend them

[byd1380]

When you fitted the trumpets did you notice much difference in power or drivability? Which ones did you go for?

Ivan