NITROUS OXIDE ( nos / n2o ) advice forum

I lost the will to live in the dissociation thread, but yes I can see the line of thought.

I understand the culture of this forum is to have esoteric and highly technical discussions, but it's beyond my pea brain. Just give me a basic setup and let's get out and race

Hi stephen,I understand what you're saying,but I think that what Trev's trying with this thread,is to see if it needs a complete rethink to go further with nitrous.

He's suggesting that,rather than start with an NA tune to get as much as possible out of the "base package" and then "top up" with nitrous.Why not use nitrous from the get go,just as you would a turbo or blower?

So if you were to go this route,then what would you need to change?

I'd guess he started with cams and cam timing,as beefing up the exhaust side has been suggested before.

We do ask simple stuff too but it never hurts to learn something new

Ya can always talk to me im Thick , not very skilled at racing but i never turn down a challange even if i know im going to loose , and i seen ya bike and it run and i dont recon ya got a pea brain at all

Tezz

so i ask again do ya think one of reasons inlet cams (cast) break more than zorst is to do with the cam chain run the short bit from zorts to inlet

last ear i went wider with my cam timing for better 'breathing' at the top end, worked well. 111/114 i think, but talking to people at the pod some said i should have gone smaller centers for gas. i can see both sides of the argument, so looks like we need a dyno session with some cam timing changes between runs
Stephen, esoteric, my favorite word, and the motivation behind most things i do.

I have no Nitrous specific experience on this but.

In my experience closing up the lobe centres increases top end at the expense of mid range torque, so given that nitrous tends to increase mid range torque the combination appears to make sense to me.

ah, i may be getting my vernacula wrong

i've been told going 'big' centers helps top end. ie from 109/111 to 111/114 as i did last year. i thought this was going 'wide'. am i correct? on either count?!

could be wrong as although it appeared to rev more freely at higher rpm, i also had some head mods done, so not a good test bed.

In your example you've only changed your cenres, relative to each other, by one degree.

Going from 109 to 111 on the inlet will make the motor more top endy, the exhaust from 111 to 114 in my experience will make very little difference.

dont most just stick a zorst cam on inlet then add gass

Maybe to clarify a little,

In my experience 2 degrees on the inlet will make a measurable difference, exhaust much less so.
I tend to time the exhaust cam to suit valve to piston clearance only. (as long as its between 105 and 115)
Inlets are much more crucial.

There maybe some confusion possible on "wider" lobe centers.
In my mind 105 inlet, 115 exh is wider than 115 inlet 105 exh, I can see a few ways it could be interpreted differently though.

i once timed my exhaust ~130 by mistake. made hardly any difference aspirated!

i need to draw some circles with timing marked on them to get my head round cam timing

Battyone - there are already two schools of thought in bike motors for nitrous: some guys are building what they would consider to be nitrous motors, some are effectively using high compression Pro Stock motors. So I can see why cam timing would be seen as one of the elements, but clearly only one item in the mix. Are you sure you're not Trevor? - all that bit where you tell us what Trevor is trying to achieve with his line of question.

xxdrac - you shouldn't be breaking cams under at all, never heard of that one, other than where guys have dropped one on the workshop floor and then had it break later. You need someone to set your cams up for you, breakage sounds like you are getting basic setup wrong.

gsf1371 - your wide setup sounds good to me for a nitrous motor and you would find some very quick guys in Pro Mod agreeing with you.

Sorry for the three in one answer, been watching the footie

I'll try and get some data out of guy at CPL the hondata systems have a facility to swing cams,he can then measure back to back in a few minutes rather than hours or so.
The cars normally make massive power compared to the gas added,from what I've heard not many come close to what you're trying to achieve on a bike ie the target in Superstreet bike is at least 200bhp over the base power.

That will be useful Brad, I have no concept of what power nitrous cars make and what proportion comes from motor and what from nitrous.

For bikes I think 200bhp from nitrous is about where it stands at present and probably 250bhp, maybe a little more, from the motor.

For the rest of the guys, Pro Mod is the nitrous class for bikes and they are limited to a 11" slick by rules. So a lot of the work going into them at present is on chassis, as they are near to the point where 450bhp is about as much as can be applied

CPL's information would be of use I'm sure but just so you know the Honda K series only adjusts the intake cam as mentioned above as they may well have found adjusting the exhaust cam doesn't really help much.

HTH

Bill

Whats a 'measurable difference' for 2 degrees baring in mind you don't really know how much they've actually moved once set?Remember ours have been measured and move by upto 3 degrees.
Are we talking 2 or 5bhp?

Brad, I'd say 2-3 ftlbs in basic terms.

I take your point about the fluctuation in timing but, if you adjust the timing it will be fluctuating around a different point. The amount of fluctuation will be the same.

We also use motec and can see the movement of the cam but, if timed accurately 2 degrees of inlet timing does make a repeatable difference.

I assume you mean peak torque what rpm?Its just that getting repeatable results after stripping the topend down and rebuilding after spinning the cams about can vertually be measurement error at 7000 rpm on a Busa you may see 3bhp if you're lucky.Obviously you'd lose that from elsewhere,thats vertually in the measurement error zone for us and you wouldn't be able to feel or notice any benefit from that.
The ammount of fluctuation maynot be the same either depending how the camchain tensioner settles back in.
Putting different bellmouths on however can have a huge effect changing the midrange by 10bhp,in the bang for buck department(£20) these out perform playing about with afew degrees here and there by miles.

Brad. I'd agree with what you say but.

I work in Superbikes and those small details are very important.

Longer bellmouths will increase the midrange but the top end will suffer. it's all a matter of balance.

if going from 105 inlet to 110 inlet, peak torque will drop and occur at higher rpm.

I realise this thread is about Nitrous and maybe this level of detail is not relative but, the point I was trying to get across mainly was how much more influence the Inlet timing made compared to the exhaust.
Also most variable valve timing systems work on the inlet side only which would support that.

I also realise the exhaust may very well be more important with Nitrous.

Perhaps we have got a little off topic.

Hoping my input will help us all, I'm just as interested in how Nitrous works even though we can't race with it.

Regards

Ian

I take it that none of the cam timing info you 2 gents have been discussing is related to nitrous use.
However any theories based on your experiences NA and understanding of nitrous would be interesting to hear.

BTW Brad you still haven't answered my question on the dissociation thread about what the torque change was (if any) between the 2 dyno tests on GD's bike????????????????????????????????????????

All of my experience with cam timing is high RPM, High output, Normally aspirated bike engines.

I'm still considering what I think may be the Nitrous case, based on my experience plus what appears to me to be Nitrous fact.

I've been watching all of the recent tech threads with interest but don't want to form an opinion too quickly if not based on real experience.

You can always post a response as "work in progress" and nobody on the forum would judge you anyway. New thoughts (even if incorrect) can often lead to better things.

I thought last night after I posted that I may need to quantify my statement.The tuning on the Busa is far easier and maybe could be seen as basic than someone like you who are building a swiss watch in comparison.The bikes race in either top speed or drag racing and cost can be big issue.The basic levels normally go Akro PC3 equals 200mph aspirated good enough to win a meeting.Drag racing its still poss to win a meeting but gas is a £500-600 set up and goes 8's and will win a meeting in 8.80 possibly.
Road warriors will go pipe and pc3 possibly with bellmouth mods depending on if they want high end power to tell the blokes down the pub about or if they like mid range grunt,short or long.
The aspirated swiss watch tuning is rare because there no a race class that its needed in to be 'only' aspirated and the expense is huge when compared to the others fore example.
Full house motor different cams dialed,port and flowed head,big bore kit,pipe pc3,airbox mods etc etc will rush you a cool £2500 to £3000.
For power that the £500-600 nitrous kit can give,in fact you'd have to put a stroker crank(another £3k) in to match the nitrous stuff.
At £3000 you're £500 away from a small but upgradable turbo kit with 280bhp potential on stock pistons!!
So not much work is done on the aspirated tuning stuff, it still occurs but if you want Busa power adders theres far better more economic ways of getting power.

The bike had issues so the data wasn't all useful.

Brad,

I understand the different jobs we do and can see your point regarding bang for buck.

I do still hold the opinion that 2 degrees of inlet timing does make a difference and is worth considering when building your engines.
However probably not worth worrying about if the engine is already built.