Jnimbostratus Street Fighter Project

[jnimbostratus]

I have to say I am disappointed in the power. It seems to just not have what it should. It feels fast and has no stumbles or hiccups but I went on the gearing commander website which indicates that with the gearing and tire size my bike has cucurrently that my top speed per gear should be much greater then they are currently. I wonder If it is a tuning issue or a tired motor or even my exhaust which is very poorly designed. Its just a 45 degree slash cut into a hole in the side of can with no packing.  Tell me what you think.

[the fan]

Do you have a tach on it and if so how does the RPM compare to what is listed on the gearing commander site?

[jnimbostratus]

I have my rev limiter set at 10,250 and put 10,000 as the max rev on gearing commander.

[jnimbostratus]

I just went back and realised that what I thought Was max rpm is max power rpm. Where the stock curve is making peak power according to gearing commander. 

How do these top speed per gear figures compare to your bikes?

http://www.gearingcommander.com

[the fan]

I don't have an FJ, but the GC calculations were pretty close for my YZF when comparing RPM to speed. This was based on use of a GPS lap timer, speedo that included a fairly accurate digital tachometer. I was able to compare the results to what I was seeing on the track.  Many things can affect top speed and a bikes ability to achieve it. Also keep in mind that the calculations are based on RPM times gearing with a correction for tire diameter.

Additional horsepower and torque will have no effect on this other than rate of acceleration and ability to overcome frictional loss.

I am not 100% sure what you are looking for but even if you double the horsepower your ground speed at a given RPM will be the same as a stock machine. Factor in the inaccuracies of the stock speedo and tach and your results can vary significantly at higher speed from what the math shows.

[jnimbostratus]

I'm just a little baffled at how far off it is. With my gearing and tire size factored into gearing commander the top speed for 4th gear should be 130 mph and I'm not hitting 100 in 4th. I wonder if I back off as it hits rev limit if it will continue to accelerate. If this is the case then my problem is the clutch still. That would not surprise me considering I attempted to remedy my shot clutch by just adding an additional diaphragm spring and leaving shot clutch pack I only did this because I am kind of in a transitionary point employment wise so cheap was the only option.

And 'the fan' I understand what your saying that all the power in the world and It won't change xrpms times ygear = zspeed. I wasn't thinking clearly before but this makes me certain it's a clutch issue thank you for helping me think clearly about it. The accuracy of my teach and Speedo I'm certain of because the tech matches perfectly the setting of the dyna rev limiter. And Speedo is gps

[Mark Olson]

3rd gear will get you over 100mph . Sounds like you are correct about the clutch.   Try to start off in 3rd gear sitting on the bike , rev to about 4k and dump the clutch .

If it slips like crazy and moves forward , the clutch is bad.
If the engine dies / stalls out , clutch is good .
If the rear tire lights up , clutch is very good. 

[~JM~]

Does your exhaust turbine discharge run into a wall, or does it flow through a nice curve? The discharge should have a smooth, restriction free flow path.

I'm not familiar with your computer issue.

Good luck.

[jnimbostratus]

The exhaust hits a wall. I plan to a dress this as soon as I start my new job.

[jnimbostratus]

Made new "downpipe" today. Flows much better obviously, what wouldnt? That muffler setup I had on this was super restrictive. It sounds much more aggressive now also.



 



After that I went to check my clutch theory eased into it and as soon as boost started to build the bike accelerated and rooms climbed to redline. Then I did it again and as soon as boost hit I pulled back a hair on the throttle and the bike accelerated like a Fucking rocketship all the way 101mph in 3rd at just about 10,000rpm. When I just lay into it I was maxing 80ish at 10,250 rev limit. So I think it's safe to say I need a clutch pack. It was incredible to see how much power it really is making tho. I believe with a good clutch I will be able to break the rear loose at highway speed. Time will tell.

[fj1289]

looked back through the thread but didn't see what you were running for a clutch...

Have you seen this?  http://www.fjmods.co.uk/Shammas.htm

6 psi boost was enough to slip the stock clutch.  He went to a Barnett coil spring conversion - that was good until 15 psi.  Went to a lockup after that


Talking with Randy for the Bonneville trip, he suggested doubling up on the stock clutch diagram spring.  Then, if that wasn't enough - triple it up!  I'll bet 2 springs will hold what you have now - and a LOT cheaper than a coil spring conversion.  But, if you get to the point 2 stock springs won't hold, you'll probably want to go to a lock up (which will require a coil spring conversion) so you can have a reasonable clutch pull for daily riding and still have enough clamp force to hold the horsepower! 

Some problems are good to have .... 

[jnimbostratus]

I installed a second diaphram spring a few weeks ago currently running 2 I think the problem is I left stock plates and discs and they are probably  shot.

[fj1289]

I'd recommend going with Yamaha plates.  As long as your stock steels aren't warped (clutch would be draggy and difficult to shift to neutral, etc) they should be good. 

You can ditch the stock judder spring at the bottom of the clutch stack and go with an additional "large" friction plate, but some people have had noticeably grabbier clutches by doing that.  I've never had an issue doing this. 

You MAY want to try Barnett steels - they are completely smooth and will have more holding power, but may be "grabby" compared to the stock steels. 

At 8 psi I'd think that 2 diaphragm springs would hold (160ish HP?)

[Bones]

How much more power can a turbo make. I know it all depends on boost settings and such, but would an extra 100hp tops be unrealistic, if so that would be about 230hp out of an FJ engine, which would put it ahead of the current super bike category.

There's a bloke on Youtube called Ghostrider with a turbo Hyabusa that's popping wheel stands at over 300 kph, crazy stuff, but shows what power a turbo can put out. Keep us posted.

[jnimbostratus]

The general idea is every 1psi of boost is good for 10-12 hp. Ther are a lot of variables tho I know some car guys that are getting 20+ hp per psi.