Jump to content
Greg Field

A Tale of Four Crossovers . . .

Recommended Posts

What causes the dip at 4k? Cam or exhaust?

Share this post


Link to post
Share on other sites

What causes the dip at 4k? Cam or exhaust?

 

I can't speak to what Ernst posted, but on the pre-2004 north American V11s the torque and power dip around 4500rpm seems to be caused by the stock exhaust crossover which doesn't have a catalytic converter like some of the later euro V11s did.

 

If you look at my post on page 9 in the dyno thread the first chart shows my bike with an FBF crossover.  The second chart shows my bike with the stock crossover.  Look at the difference between 4k and 5k rpm.  The power dip went away.  The only real change was the crossover.  Others here have seen or felt similar results by switching to any of the aftermarket crossovers.

 

http://www.v11lemans.com/forums/index.php?showtopic=8556&page=9

Share this post


Link to post
Share on other sites

Has anyone ran no crossover and what did that do?

 

 

Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

I have often wondered about that. After all it is not like a 360° parallel twin where the even pulses help extract the exhaust from the other cylinder. With our V twins we may be able design a system that helps with one cylinder but it will then hinder the other, perhaps uneven pipe lengths would work. I tried making seperate pipes for my T3, in truth I did not notice any difference, refitted the original as it was prettier than my bodge welding.

Share this post


Link to post
Share on other sites

 

What causes the dip at 4k? Cam or exhaust?

 

I can't speak to what Ernst posted, but on the pre-2004 north American V11s the torque and power dip around 4500rpm seems to be caused by the stock exhaust crossover which doesn't have a catalytic converter like some of the later euro V11s did.

 

If you look at my post on page 9 in the dyno thread the first chart shows my bike with an FBF crossover.  The second chart shows my bike with the stock crossover.  Look at the difference between 4k and 5k rpm.  The power dip went away.  The only real change was the crossover.  Others here have seen or felt similar results by switching to any of the aftermarket crossovers.

Tom

 

This is what I meant by "the power curve starts about 500 rpm sooner to rise" which makes the dip almost disappear. Rear wheel horse power does not impress me as you have the TI cans on the bike with open air box. 

When looking at your specs I would enrichen the engine at full throttle to get the mixture between 12,5 and 13. This might improve HP and makes the engine run cooler. Second measure would be to reduce ignition timing at full throttle by 3 to 5 °. Timing goes up to 44° at 8500 which is too much for an engine with good volumetric efficiency. This can be done with guzzidiag. 

Share this post


Link to post
Share on other sites

Those dyno runs were done with a titanium ECU and custom Power Commander map.  I've since gone back to the stock ECU and a different PC map.  I also replaced the modified airbox lid with a stock one.  I got sick of the intake noise :oldgit: .

 

I recently bought the cables that are needed to use Guzzidiag.  I'm going to try disconnecting the PCIII and loading a new map sometime soon.  If you have a map that you're really happy with Ernst I'd love to give it a try if you want to share it.

 

Thanks,

Tom

Share this post


Link to post
Share on other sites

Those dyno runs were done with a titanium ECU and custom Power Commander map.  I've since gone back to the stock ECU and a different PC map.  I also replaced the modified airbox lid with a stock one.  I got sick of the intake noise :oldgit: .

 

I recently bought the cables that are needed to use Guzzidiag.  I'm going to try disconnecting the PCIII and loading a new map sometime soon.  If you have a map that you're really happy with Ernst I'd love to give it a try if you want to share it.

 

Thanks,

Tom

Tom

 

I have no Maps that suit your bike as mine is much different in cam/CR/exhaust than yours. 

I would ask Meinolf - he has maps that should suit your bike well, he is active in this forum, especially in the Guzzidiag compartment. 

  • Like 1

Share this post


Link to post
Share on other sites
On 2/6/2008 at 10:03 PM, Greg Field said:

 

No, even though I was a dealer for their products, they blew me off. Needless to say, I have bought nothing from them since then. I threw away he cracked crossover. Sorry.

This is a very old post, but you know how it is.

I've signed up for a new Staintune system for the 'Sport. Currently, it has what appears to be a FBF crossover on it, with Mistral short cans. 
For what it's worth, the FBF cracked on the center weld and was repaired by welding then welding a reinforcement strip about 1/2" wide around the entire center joint. A very professional repair. 
So, when I installed the Jeffries MyECU, I made a place in the crossover for the O2 sensor; what I discovered then, is that there is actually *NO CROSSOVER*. The 'crossover' part is nothing more than the two pipes flattened and welded to each other, with no holes in between. Lovely engineering, eh? Perhaps it's better for power, I don't know, but calling it a crossover is a bit disingenuous. I have to wonder what Stucchi has done there. 

Meh.

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites
10 hours ago, Pressureangle said:

This is a very old post, but you know how it is.

I've signed up for a new Staintune system for the 'Sport. Currently, it has what appears to be a FBF crossover on it, with Mistral short cans. 
For what it's worth, the FBF cracked on the center weld and was repaired by welding then welding a reinforcement strip about 1/2" wide around the entire center joint. A very professional repair. 
So, when I installed the Jeffries MyECU, I made a place in the crossover for the O2 sensor; what I discovered then, is that there is actually *NO CROSSOVER*. The 'crossover' part is nothing more than the two pipes flattened and welded to each other, with no holes in between. Lovely engineering, eh? Perhaps it's better for power, I don't know, but calling it a crossover is a bit disingenuous. I have to wonder what Stucchi has done there. 
  


So if both both pipes have flats there must me a restriction in the pipes at that point.  Looks like a case of Form over Function.

  • Like 1

Share this post


Link to post
Share on other sites
On 6/21/2020 at 2:25 AM, 68C said:


So if both both pipes have flats there must me a restriction in the pipes at that point.  Looks like a case of Form over Function.

Yes but it wont mean a thing. No crossover will hurt the top end i'm sure but the flats wont loose you any power.

EDIT.....meant top end not mid range

Ciao

  • Like 2

Share this post


Link to post
Share on other sites
5 hours ago, Lucky Phil said:

Yes but it wont mean a thing. No crossover will hurt the midrange i'm sure but the flats wont loose you any power.

 

Ciao

Well, I suppose I stand corrected.

Assuming its not a spoof video.

Share this post


Link to post
Share on other sites
On 6/21/2020 at 9:43 AM, 68C said:

Well, I suppose I stand corrected.

Assuming its not a spoof video.

I have not watched that video from them. But they are not a spoof and they do great work. They did a great segment on oil level, showing how too much oil not only costs horsepower but it also hurts oil pressure at higher rpm (the oil gets aerated by the crank and aerated oil will loose oil pressure).

They are serious, and pretty smart.

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...