roadrunner
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| posted on 16/10/07 at 06:05 PM |
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ZX9R VACUUM VALVE
Now that i fitted my air box, i was wondering weather it was worth fitting these valves back on to the engine, i dont have them so i would have to buy
the bits required, is there any advantage doing this .
Thanks Brad.
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matt.c
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| posted on 16/10/07 at 06:14 PM |
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Why have you gone back to you original airbox?
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roadrunner
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| posted on 16/10/07 at 06:32 PM |
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Because all the experts said that the carbs prefer still air around them.
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matt.c
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| posted on 16/10/07 at 06:47 PM |
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What even if the airbox will be cut and hacked about so its not in its original dimensions.
Sorry if i have just opened a large can of worms!
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roadrunner
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| posted on 16/10/07 at 07:24 PM |
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because of the angle of the engine and carbs, i have only cut out about an inch or so from the top edge, so volume inside the box has'nt changed
much, i will take a pici to show you.
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roadrunner
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| posted on 16/10/07 at 07:35 PM |
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Removed the bonnet to find one of the ally covers has come off.
 
air box fitted
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matt.c
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| posted on 16/10/07 at 08:12 PM |
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Hmm, now you have got me thinking! 
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mistergrumpy
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| posted on 16/10/07 at 09:03 PM |
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Have you left your carbs jetted then or are they back to normal? Can't remember if you've answered this once sorry Does th'engine
run any differently now? (Sorry I can't answer your question and have just replied with loads of my own!)
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Andy W
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| posted on 16/10/07 at 09:33 PM |
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That's how I run mine, with standard jetting
 
Chopped airbox
Andy
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matt.c
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| posted on 16/10/07 at 11:07 PM |
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Ok so how much on avarage is the BHP of the ZX9 with the standard air box and standard jets?
Putting an after market filter and using new dynojets, what BHP then?
Do you loose BHP or gain BHP when using aftermarket parts?
Is there much difference? Is it going to be worth the money spent on these aftermarket items over the standard stuff?
Oh! Sorry for hijacking the thread.
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roadrunner
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| posted on 17/10/07 at 07:11 PM |
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I dont have the standard jet's, so the ones that are in are 185, it does need setting up again though, as for power, a standard engine is
supposed to produce 143bhp, with after market filter and dyno kit it might be another 5hp, maybe more, i'm not quite sure.
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matt.c
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| posted on 17/10/07 at 07:18 PM |
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I have to remember with mine is that it will have to go through a SVA so the emissions might be a problem.
Using aftermarket filter/jets, will these help or make the emmisions worse?
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roadrunner
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| posted on 17/10/07 at 07:21 PM |
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Depends on who sets it up, if you get it rolling road set up, they use the emisions to change jet sizes to suit air flow, Boggs will do a good job.
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Jimbob
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| posted on 17/10/07 at 10:33 PM |
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quote:
Originally posted by matt.c
I have to remember with mine is that it will have to go through a SVA so the emissions might be a problem.
Using aftermarket filter/jets, will these help or make the emmisions worse?
I failed SVA twice on emissions and looking at your avatar you still have air injection system fitted? junk it for SVA, will fail on lambda(thinks its
too lean)
i run a pipercross filter and dynojet needles and it sailed through
James
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progers
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| posted on 18/10/07 at 07:41 AM |
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The amount of BHP you can generate is not going to improve if you fit a foam filter. The only advantage is reducing height of the engine assembly. If
done well it can give similar results to using the standard airbox.
Regardless of this, you are almost certainly going to need to rejet the engine, even if you do use the standard airbox. Why? well the jetting is
affected by both the intake (airbox/filter) AND the exhaust you use. As all kit cars will have some kind of custom exhaust and can, rejetting will
optimise your fuelling for this setup and give you the max BHP you can achieve with the given compnonents you have.
FYI, 9 out of 10 racers use airboxes on their BECs - as they are not so worried about noise you can deduce that they think it has beneficial effect on
performance....
Cheers
Paul
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matt.c
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| posted on 18/10/07 at 09:05 PM |
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quote:
Originally posted by progers
The amount of BHP you can generate is not going to improve if you fit a foam filter. The only advantage is reducing height of the engine assembly. If
done well it can give similar results to using the standard airbox.
Paul
What do mean by "done well" ? Whats the best way to fit them?
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progers
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| posted on 19/10/07 at 08:53 AM |
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Hi Matt,
The main thing is to ensure lots of non-turbulent cool air going to the filter. If housed under the bonnet lots of hot air from the engine and
radiator can reduce the power you can achieve.
If under the bonnet you need to shield the intake from these heat sources and feed some cool air from the nosecone directly to the filter if possible.
Rich Miles website (http://striker.r-one.co.uk/) shows how he did this to good effect. Notice how he smoothed and reduced the height of the intake
pipes to each carb - just smoothing this airflow will help with power, especially if you do not use the original airbox rubbers.
I originally had an MK indy R1 (carb'd) and managed to get good power out of it (135bhp at rear wheels on TTS rollers) so it can be done. It
much easier with the standard airbox with a ducted air feed though :-)
You will know if you have succeeded as you should be able to get around 120bhp on the rollers if its setup well (a bit more than a typical blade).
Make sure you have a 4-2-1 exhaust, a cheap 4-1 version will also limit your HP. If you search around you should find exhaust dimensions that have
worked for other people.
Hope that helps
- Paul
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