Originally Posted by
houston
silicone filled intake ramp does do a few things , most noticeably the reduction of the staged idle by filling an airpocket that completely disrupts incoming flow of air/fuel when going from high vacuum to low vacuum on the intake of the crank , noticed a HUGE difference in the way the engines tuned off throttle and it threw me for a loop back in '06-'07 ish when the 821b was the first engine to come with the lightened crank that was unfilled . one thing i can tell ya is every single one of my multi repeat customers from all over the world have tried both and prefer a filled crank , we all do things a lil differently , we all have different opinions , we all feel things that others dont .
i have met well educated people in all different fields who thought they were the masters of what they studied in miss even the simplest of things looking a project over because they were too concentrated on the "deeply technical" aspect of the job
I have been meaning to comment on this one, but have been too busy to sit down and do it !
Anyways every engine is different in how it responds to having the crank stuffed.......some engines pick up power, some lose power....... I do not think the ramp itself has much effect on the mixture path and the differences we do feel are a response to the change in crankcase volume more then anything else...... But where I have seen the ramp affect the engine is when too much silicone is used to ramp the crank and it gets in the way of the mixture path...this hurts power, and I have seen it on the dyno......... If you think about it, the more places the mixture makes contact, the more separation it experiences ..just like sticking your fingers in the patch of a spray can.... The less we contact the incoming mixture the better the mixture flows with the least amount of separation.. All too often i see cranks that are over stuffed ..which not only causes a loss of power, it also reduces the engines mileage........Some factories cranks are actually over stuffed right off the bat, and can see noticeable improvements just by opening the channel up...they not only pickup power, they also usually pickup runtime.........In the end the crankfiller should not get in the path of the incoming mixture...filling a void in the nose of the crank is one thing, but partially blocking the intake path with a ramp of silicone is not a good idea. IMHO.....When I fill a crank I try to make sure my ramp will make as little contact with the mixture as possible....
This season I did a test comparing filled crank vs non filled crank using the Bonito...... Judging by whats written on these forums It seems stuffing the crank on the Bonito is believed to be the single most important mod that can be done to it.......As apparently this mod brings out the bottom end of the engine........... I actually ran a non filled Bonito vs half a dozen of the filled Bonito's all season long on the track.....During the season we all swapped controllers back and forth , and even did a few drag races.......You cannot tell which Bonito is filled and which one is not...these is absolutely zero difference on the track..... not one person could tell ..... The Bonito with the non filled crank had just as much bottom end as the filled crank Bonito...and whats really strange is the non filled crank engine actually was a little better on fuel.......
Anyways here is a video of the modified Bonito that does not have a filled crank.... It has massive bottom end and has no issues with idling down....so in the the end what was said/thought/sold to be the most important modification that can be made to the Bonito ended up being quite worthless for improving its performance.....And this is not just dyno testing, this is a pile of on track testing with some pretty skilled/experienced drivers....There are dozens of modifications that can be done to a Bonito that are a thousand times more effective then putting silicone filler into its crankshaft...Now of course I have not tested every engine out there in this manner...
sorry for the long post guys, but I figured I have some good insight into this, as I did do a pretty thorough test on this during the season....cheers !
edit: in no way am I implying anyone else info is wrong or false....i am just relaying what I found with my own Bonito and several other engines I have tested..