Horse power vs torque

So they dont get muddled and lost in the directory, please post your tuning questions here.

Moderator: Moderators

Post Reply
Robbie
Posts: 194
Joined: Mon Mar 23, 2009 9:20 pm
My Bike: zxr400
Location: Perth
Contact:

Horse power vs torque

Post by Robbie » Fri Jul 31, 2009 7:41 pm

Im hoping some of you guys could help me out here.
I tried a different set of carbs on my race bike as they are set up different. different bellmouths, air correctors blocked 102 mains and dyno needdles on lowest clip and it made more power on dyno 79bhp up 1.2 bhp and cleaned up the dip a little better at 9.5-10,000 rpm all looked better but lost torque down 0.6 kgm from 4.8 to 4.2kgm which is about 4ft lbs if im right? It looks like I could go up on the mains.does any body have an idea how to get the torque back and keep the hp?? hope it makes sense.cheers.

User avatar
tk400
Posts: 221
Joined: Thu May 26, 2005 10:50 am
My Bike: ZXR400 , ZXR950
Location: Australia

Re: Horse power vs torque

Post by tk400 » Fri Jul 31, 2009 10:22 pm

can you post a graph of torque and HP over RPM. And if possible the old one as well. Also give us a quick run down of your engine specs max RPM and weather you have SP gearbox or not. cheers

REgards TK400

Robbie
Posts: 194
Joined: Mon Mar 23, 2009 9:20 pm
My Bike: zxr400
Location: Perth
Contact:

Re: Horse power vs torque

Post by Robbie » Sat Aug 01, 2009 9:12 pm

I will try and get dyno print out posted up.
As far as I know engine is sp cams ported polished skimmed head full mercury system,totall loss,ram air,was set up with 112 mains, standard needles,air correctors blocked.now as stated.the prob with the dyno is it is older type without air/fuel meter.cheers

User avatar
tk400
Posts: 221
Joined: Thu May 26, 2005 10:50 am
My Bike: ZXR400 , ZXR950
Location: Australia

Re: Horse power vs torque

Post by tk400 » Sun Aug 02, 2009 8:04 am

If you like you can PM me and I will supply an email address you can send the Dyno data through to.

User avatar
tk400
Posts: 221
Joined: Thu May 26, 2005 10:50 am
My Bike: ZXR400 , ZXR950
Location: Australia

Re: Horse power vs torque

Post by tk400 » Sun Aug 02, 2009 8:09 am

4.8 sounds pretty high for that HP at what RPM was that at. what are the dimension difference between the old and new ram tubes. Also blocking off the air corrector jets is a band aid tactic. It does however make the setup less prone to atmospheric changes. The main problem is poor fuel atomisation caused by poor emulsion when blocked off. cheers.


Regards TK400

Robbie
Posts: 194
Joined: Mon Mar 23, 2009 9:20 pm
My Bike: zxr400
Location: Perth
Contact:

Re: Horse power vs torque

Post by Robbie » Sun Aug 02, 2009 7:58 pm

Image

Best I can do the now as I dont have a scanner.The run in blue is with the choke on.cheers

User avatar
tk400
Posts: 221
Joined: Thu May 26, 2005 10:50 am
My Bike: ZXR400 , ZXR950
Location: Australia

Re: Horse power vs torque

Post by tk400 » Mon Aug 03, 2009 9:53 am

Dont get to carried away with figures. HP is a function of torque, torque is derived from peak cylinder efficiency. So in order to gain more peak HP you need to increase volumetric efficiency at that point. This gain has probably come from the harmonic tuning of the new trumpets being optimized closer to the peak HP, As a result of this the optimization is now not beneficial to the lower RPM closer to peak torque. Are you running 4-1 pipes as that dip is pretty bad, you may want to reduce your overlap via cam timming to reduce that issue. cheers

REgards TK400

User avatar
tk400
Posts: 221
Joined: Thu May 26, 2005 10:50 am
My Bike: ZXR400 , ZXR950
Location: Australia

Re: Horse power vs torque

Post by tk400 » Mon Aug 03, 2009 9:57 am

Why only 14500rpm ?

Robbie
Posts: 194
Joined: Mon Mar 23, 2009 9:20 pm
My Bike: zxr400
Location: Perth
Contact:

Re: Horse power vs torque

Post by Robbie » Mon Aug 03, 2009 5:44 pm

belive it or not that dip is now better than what it was.what do you think is the best route for setting them up?leave the air correctors open and go with massive main jets?Does anybody else have dyno print outs of theirs and a different set up?It is just standard ecu does that explain the 14,500 rpm?cheers

User avatar
tk400
Posts: 221
Joined: Thu May 26, 2005 10:50 am
My Bike: ZXR400 , ZXR950
Location: Australia

Re: Horse power vs torque

Post by tk400 » Tue Aug 04, 2009 8:52 am

I had assumed it was an SP with flatslides due to the talk of ramtubes. Therefore I assumed an SP limit of 14,800 rpm with standard SP Igniter. Maybe the carbs deal better with reversion from the exhaust when air correctors are blocked. I think you should look at cam timing and overlap specifically, As for the air correctors unless you can put an AFR chart on that power curve its going to be harder to give acurate advice. Any chance of a copy of the old power curve?. cheers

REgarsd TK400

Post Reply