NITROUS OXIDE ( nos / n2o ) advice forum

Hi Tez, i think the saving point here is that running carbs, it doesnt really matter what reading you get off gas as your carbs look after themselves, as in once they're set, they're set so to speak, so for you at the moment, the only readings of interest are on gas. Now, as you say, the quantities of oxygen/fuel will change as ya ramp the gas up but as long as you're under 11.5 AFR during the run you will be richer rather than lean, now if you switch fuels, this could change depending on fuel, but as long as you set carbs first, using plug as a guide this will give you a base figure from which you can drop a couple of points for gas use

Steve

Steve i hate to disagre but petrol is 14.7 to 1 race or not....i have seen street motors with race gas and small shots at 13 to 1 so it really depends on the engine and where your taking the value but petrol is 14.7 to 1 now maybe a bit differant for a oxygenated fuels. I can also show you where race motors are sometimes at 13 on the AFR under load....Wheres Dave taking his reading from and is it recorded? Whats his compression and dynamic once again I ask...
Tezz the point of the fuel on Daves bike i feel is the best and here again its such a short runner to the intake valve that the fuel needs all the time it can to vaporize so especialy at higher speeds it needs to be at the bell mouth..now once again not seeing all this working so i can only speculate its at low RPM,s I think there may be a issues..Look at F1 and where its located and they had 2 nozzels for differant rpms there at the bell mouth for top rpms and some of the fastest imports in the world have there injector over the bell mouth...these are higer rpm motors much like a bike engine...

Now i have no idea of how much fuel stand off there is and once again I cant comment on something i havent worked on but I do see issues and also leads to incomplete combustion if its not vaporised...Once again to close to the valve would be worse on this app. in my opinion.

Tezz wrote:
Thanks Steve kind of what i was getting at , is do you ajust your target A/F to the different fuels and when using nitrous

Ive seen post of peoepl using 11-1 12-1 Na but dropping this to 10-1 using nitrous and plugs at both look ok , now if 12-1 is NA and 10-1 is what they set it for nitrous im guesing in the transition period there will be a variable if you set sensor to maintain 12-1 when you hit gas it will think you rich if you set at 10 -1 it will think you lean before ya hit gas or same if you have a seperate tank that runs race gas for nitrous and pump for NA , not a problem if you launch and use Nitrous from line i guess unless you have a slow reacting sensor

or are they wrong and what ever you set at NA when you fire nitrous it should be same ?

this could get very confusing if you have an NA system and a seperate tanke with race gas for nitrous if the values are different IE not both 14.7-1

Hmmm wideband with data logger looks to be even more important

Hi Tez, i think the saving point here is that running carbs, it doesnt really matter what reading you get off gas as your carbs look after themselves, as in once they're set, they're set so to speak, so for you at the moment, the only readings of interest are on gas. Now, as you say, the quantities of oxygen/fuel will change as ya ramp the gas up but as long as you're under 11.5 AFR during the run you will be richer rather than lean, now if you switch fuels, this could change depending on fuel, but as long as you set carbs first, using plug as a guide this will give you a base figure from which you can drop a couple of points for gas use

Steve are you saying you cant adjust your carbs for AFR or even lean them out? am only asking becuase i dont know. On a race car i have 3 circuts witrh air bleeds that i can trim the fuel out so it has a smooth BSFC and there for a smooth afr and much better running engine thru the RPM and then when a jet move is made its constant with that change..Not sure what you have so please help educate me on your carbs please...

S

I see what you saying about the fuel injectors in belmouths but then you also injecting nitrous at the same point as well as sucking in your Na charge on 4 manifolds that are not linked and have little room for storage

but at some point the volume of nitrous when using a discharge tube and the very dense jet of nitrous will hit a closed valve and have nowhere to go but backwards and the could fule bepushed out of bell mouth into free air , ive seen vides of nitrous being backed out of bike carbs , what im woundering is if the nitrous can get backed out can fuel as well which would then leave from vavle to edge of belmouth just full of nitrous , in a car it would only get backed out a bit but fuel still inside the manifold as it sealed so to speak

Tezz once again were talking about fuel stand off...and there are IR mech and electronic intakes that this happens on also...this is why you use differant length ram tubes as to help smooth out the pulses and to help reduce stand off..hell i can show you a F1 at 18000 and there are in some areas of the pull where it has some stand off...now the pleanum there is the box over the injector stacks...and i dont know the air intake set up but think about one of the stoutest bikes made Yamaha Vmax thats they after 20 years updated and how the ram effects work on that...

Putting the ntrous out at the bell mouth has advantages and disadvantages and one advantage is less bouncing off of the valves as there is more of a chance for this if it was closer...or under the throttle...

No one has yet told me where there reading AFR....and here is another thing about AFR if you have a slight leak in the exhuast it will pick this up as O2 so lean..unless you have a 5 gas analizer this is the only true way to know what going on with reguards to the fuel and mixture PERIOD...use it as a guide only and if its in the pipe after the colector then its not helping you tune at all with a nitrous engine. Its only good in each pipe like I said...

Hi Johnny,
No, the point i was making about carbs in this case, is if they are jetted correctly prior to firing nitrous on Tezz's set up, they will be right during the pass, so the part affecting the AFR is the nitrous and additional fuel.
As AFR is a ratio of oxygen/fuel then oxygenated fuels will effect the stoich mark. Import carries 6% oxygen which would reduce the stoich to 13.8 AFR. So effectively reducing the required AFR window by the same amount.
I see what you're saying regards injection points, although i always had it in mind that higher rpm's allow shorter runner lengths as the increased gas velocity allows atomisation to occur much more quickly, hence why for lower rpm's the runner length needs to be longer. Certainly if i space my carbs further back i lose horse power at the top but gain in low-mid range. Thinking about it, i guess reversion is also less of an issue at high rpm as the velocity of gas will pressurise the inlet to an extent because of the inertia involved and a more constant flow because of the increased amount of valve open moments.
I must admit from my own experiences, i run open backed carbs, and if you crack the throttle open you can see fuel/air mix being blown back initially untill engine catches up, which i assume is reversion. This normally only becomes visible around 3-4000 rpm which is also where the engine is at its least efficient having a flat spot there.
As for Daves set up, i dont know where he takes his AFR reading from or what his static and dynamic compression figures are, though i may be able to find out over the weekend as we are both racing, if he doesnt come on and answer first lol.
By dynamic, do you mean the pressure of compression? For example, my engine has a CR of 12:1 and gives 200psi on compression test.

Steve

Hi Steve,yes your right that short runners are best for higher rpms but what I was saying I think in reguards to pulses for stand off or reversion is that the Ram tubes above the throtle on cars are adjusted to help the pulses...now this doesnt effect the runner length. If you go to Kinsler fuel injection this is a great sight and down load the book theres alot of info on fuels and also nozzle placement, Dave Kinsler is one of the smartest men onfuel and FI and is one of the people who halped make Lucus FI products do so well in racing back in the 60's and he left GM to start his buesiness abuot the mid 60's... He is the one who actaully did the testing for the information so the first tunnel ram was made...cool stuff anyway there alot of manifolds he makes....
Even bikes.....

Reversion is a issue mainly when problems in the intake accure and wrong cams and or carbs are wrong..there si going to be some but what we see alot of and not like we did is the carb stalls after alot of system go off in the intake..but better carbs and off course i have a great nitrous system also....

I guess i should explain my self better but the runner length is really effect more when its shortened or lengthend under the throtle and where the fuel is coming in at,now it will effect it above but nothing like below and its usally staggering the stacks is what they do to help with tunning the ports for engine pulses...

I am sure we are also having a Ebglish to American translation issues with this too...LOL

it look like the sensor for 02 is in the bottom of the pic after all the headers join into 1

http://img233.imageshack.us/img233/6053/55rl.jpg

this is injector revo lay out

http://www.noswizard.com/hpsnw_admin/im ... evo3sm.jpg

Thanks tezz..yes the o2 i see that and your right about its location..hmmmmm oh well ....I am not going to knock anyone and I hope no one thinks I am..but I have stated it all above not going to beat a dead horse on O2's

That location is fine for turbos or NA efi...thast all and of course daliy drivers for emmisions

Got Ya
will have a look at that site soon as i get chance, busy tryin to get off a speeding ticket at the moment lol.
I think it may be an idea to continue this in another thread as we seem to be hijacking this one, although it came about directly relating to Daves bike. But i think theres also a lot of info that might benefit other ppl as well as ourselves if it was posted under its own heading where poss more ppl will read it.....
Like evrything else there is just soooo much going on within this one small part of the overall tuning concept that its a wonder anybody goes fast lol.

Steve

Agreed..sorry also to all those also..didnt mean to hijack it...if you start it send me the link please...

Does anyone know if Dave is using another fuel for this weekends outing?

Good Luck Dave...

Have opened a thread here: viewtopic.php?f=5&t=5296 to follow this subject on

Not sure Johnny, will find out

Steve

Jeez it all looks too complex to me!
when I started with the 1st Revo (dry system - easy life!) on the streetbike I was using Tescos super! and it happily ran 8.8 despite my incompetent clutch control

running VPImport - wanted to try VPNOS for ages (years!) because it looked like itd do the job and was a shed load cheaper! however I couldn't get the importer to get me a can and in the end I gave up and stuck to VP-Import as it apeared to do the job. prior to that I ran VP-C23. Import gave me no problems with 250bhp of nitrous through pulsiods whereas I was deting plugs with C23 at 200bhp (with bigshot NOS sols...) IN ADDITION TO THAT Im now running about 10.1:1 compression as opposed to c.12.4:1

this weekend Im using Import (still) - though it doesn't smell anywhere near as nice as C23... and that's important!

cheers for the support guys! I'm not worthy, but will try my best. I could do with a hand at the Friday test session if anyone is there and twiddling their thumbs... I've crew for the weekend, and Trev will be there as soon as he can make it, but I could do with a hand 1st thing as I'd like to do a N/A pass (first time in about 7 years!) ...scary I know! how will I concentrate for so long! it's gotta take 9 seconds at least!!! I'll be asleep within 8 It's geared for just under 200mph so might take even longer...

Hi Dave,you know this is the problem again as your using a high octane fuel for a low compression engine and belive it or not your det. problems are due to lack of complete burn because you dont have the compression to hold the heat to burn the fuel..and what happens in a incomplete burn is whats left over are called free radicals and those are unknown particles of unburned fuel that turn into hot spot that causes pre ignition then detination....

i had to learn this the hard way also Dave and it was very costly...just trying to help you and hope i dont get laughed at to hard...You couldnt really use the VP N2O as it requires higher compression to hold the heat so it can vaporise the fuel as its low RVP and flat heat % will not do any vaporizing in the runners...

The sunoco that Steve is going to use i think would be a better choice for what you have but its your ride sir and i wish you all the luck and be safe....

Dave i never knew your bike was only 10-1

Do you have any logs of fuel on a run pref some where it did not go bang and your last few runs if possible to post so can have a look , My gut still says this gose back to fuel problem

Best of luck M8 at weekend hope you get to bottom of it

Dave also if ya have a chance some pics or your current set up and the position of crossfires that you are using for statics and test runs

as for the wide band position it seams to me thats not a good place , dont know about your bike but mine if im going to have a problem its always the middle 2 that show it 1st and i know my No1 always shows a tad richer

dont get me wrong im not saying what causing all your problems , i Gen do have an interest in why and only information can answer my questions , it may not be a pop theroy but so far in my head i cant see how you match a fuel revo to a nitrous one with out the max almost being an ECU and full data loged runs and the fuel side almost replicating FI and also factoring in injection point and atomoziation of fuel and Gs if i remeber on you bike at one point can be 6Gs

I honestly hope im wrong and this weekend ya get it nailed down and it was just a mix issue , lol showof 9sec Na pass lol , do try and keep awake , i would still have loved to see an pulsiod NA run or a log from a few of them

Fingers crossed for you and all your team

Tezz

Yeah, 9 seconds is a long long time..... No sorry, i MEAN, its been a long long time since i ran a 9!!!!! Which is not ideal for someone in the 9.50 class LOL. Doubt we'll be there early enough to give ya a hand tomorrow mate, but will come have a chat with ya. Interestingly enough, have just scored a deal with sunoco dealers, and its a damned sight cheaper than VP, so if ya wanna have a sniff? Lol
Anyways, hope testing goes well and catch ya laters

Steve

cheers guys

I'd never laugh at anyone

its certainly a number of factors, some of which I don't have the cash or time to fix I've resigned myself to identifying the big ones and then calling it a day.

getting logs off the laptop tends to result in it throwing a wobbly - and I've lost loads of them when it crashed severely - I'll give it a go sometime.

If I were me I wouldnt start where I am now, unfortunately drag racing will only make you well off if you started very rich - I started with this bike cos I got a pay out from an ex so I blew it all on the bike

and I can't get any more knots in the shoestring

see you at the track! I'll be the one being very careful

Sorry to hear you Thinking of calling it a day Dave , how many pulsiods do you have maybe with limitations you have taking it back to basics would be a cool move , lol just keep dumping more gas on it , I like the pulsiods think they great bit of kit and way infront of the compertition , I love the idea of the nitrous revo and match to a dry set up is way out there , i think more thought needed for fuel side for wet and that will mean as you pushing the limits More melt downs but thats just my my view

that engin should eat 150 shot as if it a snak , if its a choice of call it a day or revert to what you know and can easily tune within your limits i know what i would do , but that depends if ya like the buzz , i still recon with pulsiods and some tweeks could be a sweet ride

Respect

Tezz

Dave i cerntainly understand all and where you coming from and have been there.... Good luck this weekend ....I do know its really hard to see it all clear while your in the thick of it. It was only after I could stand back and away with a clear mind and alot of research to explain things that i did and saw and really didnt understand and didnt like what the norm explanations were....trully now I see it all so much clearer ...

Well then its a step forward then for sure as unfourtantly he has to race the track condistions as you well know. thats good he is in the feild for Sundays race and he doesnt have to thrash tonight and can relax and enjoy the time at the track....

All my statements were areas to look at and what could be happening, they were suggestions as its hard to tune something 3500 miles away when i cant see everything....

Is Any going there tomarrow also then?

Not only is he fighting the track conditions (which are FAR from ideal) but he's also in a totally unknown area with his chassis and wheelie bar set up, because he only just discovered that his sprocket/wheel alignment has been out for a few races (at least) and he's been using the wheelie bars to correct the less than straight running its been causing. Now he's got the sprocket and wheel alignment correct he's having to start over again with the wheelie bar settings.

All things considered 7.8 is quite a respectable time in less than ideal conditions (been very windy in the UK today), on a less than ideal track (I believe it was wet until diner time), on an unknown chassis set up and on low power, very safe settings being shut off 1.5 secs before the finish line.

I know ALL your intentions are for the good of others Johnny (which is more than can be said for Tezz, who has OBVIOUSLY been on a mission to spread negativity throughout the forum of late) and I also know how hard it is to tune from such a distance, as I tried to do so often in the early days of you using my system and all the American customers since, so its all good between us.

Even though Dave is doing quite well, that doesn't mean that your advice was not correct and not needed, because at some point it may very well apply and be the solution to the problem, so I'm not saying we have all the answers (far from it) but we have found a number of issues that we KNOW were EXTREMELY LIKELY to be responsible for the recent failure/s and we have INDEPENDENT expert motorcycle opinion to support our opinion, that a good deal of the cause of previous (and potential future causes), is the generally poor condition of the cylinder heads and this is based on a good deal of previous experience.

All we can do is keep our fingers crossed that all such issue can be dealt with or at least set back by accurate mixture and timing settings, safeguarded by the AFR safety window feature that Dave now has set at a SAFE level.