bhp results of bike carbing.

hi all, seems to have been a lot of interest in bike carbing our dubs recently, so about 6 months ago i bit the bullet and went for it. my car is a mk2 with a 2.0 16v lump, spec as follows........

9a bottom end
kr head
piper cams 274 in 276 ex
4-1 branch to magnex system
zx9r (ninja) keihin bike carbs 40mm
yamaha R1 fuel pump
dubfab alloy inlet manifold (same as bogg bros)
megajolt ignition control.

well yesterday i took the car to my local rollin road/engine tuners dynotech in ripley derbyshire, he spent about 3 hours fettling to get the best out of my setup and the results are as follows..........





so as you can see its makin 170bhp and 160 FtLb of torque which im pretty happy with. Air fuel ratio hit 13.9 highest at 6400 revs. time to ring the man in the shed i think!

comments and views welcome, how do you guys think the graphs look? any room for inprovement?

 

Did you do a power run on the original fuel injection, before you installed bike carbs?

 

Thats exactly what i wondered

Do you have a `drive-by` clip ? I`m sure it sounds awesome

 

no i didnt, bought the engine and sold all the injection bits before fitting it, the money raised from the bits went towards putting it all together. why you ask? i know people get similar results using the standard injection etc

as for the drive by clip, not yet but gonna get one! the sound is soooo addictive!

 

I've never found a direct comparison between fuel injection and bike carbs, ie same engine (pre- and post- conversion) or 2 different cars with exactly the same spec otherwise (eg, exhaust system, smae block, capacity, camshaft, ignition setup etc) - and on the same dyno.

Would be interesting if anyone does have that kind of comparison.

 

yeah i would like to see a comparison too, would be a very interseting read, what sort of torque do the injection cars make with 2.0 16v? i thought 160 ftlb was good but cant remember what the injection varient make

 

wow amazing torque figue, you may be able to get an easy 170bhp on k-jet but doubt you will ever top 140ft/lb though. Bet it pulls brilliantly!

Edit: My 6A/KR made 162.5bhp and 133ft/lb without the WUR mod being done, id expect 5 of each minimum after the WUR.

 

yeah i thought the torque was good, not sure what its down to, cams, carbs,mapable ignition etc. really gonna look into a man in the shed/mr hill climber head now. should push the numbers that little bit more. was wondering whether to get a vernier pulley too? are they gonna be worth the 100

 

very nice

i love the sound of a bike carb'd 16v

whats it like on fuel.....?

 

to be fair its really good when not on the loud pedal, well sit in 4th at 1200rpm through town really happily too. however start squashing the loud pedal alot and as expected drink drink drink!

 

whats it like getting into a track day with carbs? I heard that it's mainly induction noise as apposed to exhaust that people fail on and carbs are pretty noisy

 

i'm not to sure? they are noisey tho. hope its not above the limit tho cos i wanna do a couple of track days this year.

 

Its nothing well made enclosed air box cant silence if required for track day noise tests

Dont forget well made air box will add power to!

 

Its not been a problem for me, last year I ran a KR on Dell 40's through an Ashley 4 branch system, was 90Db at Cadwell and 94Db at Hullavington.

Running an ABF hi-comp on Dell 45's through the same exhaust this year, now that one is a bit noisy on the induction, but pretty quiet out the back.

 

Mines supposedly 180bhp/153lbft. On K jet.

 

That engine has more capability hidden in it. Peak torque at 4800 as you cannot get your mixture richer at higher revs due to jetting compromises with the carbs.
Next steps would be to get it on fuel as well as spark control and optimize from there. After that you can opt to decrease head flow restrictions and recalibrate again.
Rather than compare this reading with other dyno readings I would concentrate on extending that torque peak a further 800rpm as you do have the right components to do so.

 

thanks for all the comments chaps

toyotec,
how do i get the torque to hang on another 800rpm? is it just fueling?

 

That where I would start. You present "optimum" spark settings will also change as well.
Also cam timing optimising can also aid. Got to be careful to isolate the interactions to clearly determine progress.

 

thanks for that. im sticking to the same rollin road so i can get back to back comparisons. is a flowed head gonna help things much or should i concentrate else elsewere?

 

Flowed head will increased the volume of air transposted to and from the cylinder. But first you need to optimise the base engine.