Ive just installed and tested a WON nitrous system on my car. Its working pretty well at the moment im running a 25 shot with 25/50 jets and an afr of around 10.3:1 i intend on leaning that out slightly to 20/50 jets but ive got a couple of questions about tuning and monitoring of the engine.Its a single point system and i have been running it in conjunction with 21psi from the turbo
I have a wideband but is it realy worth geting an egt guage aswell as i havnt had much experince listening for det and find it hard to listen watch my afr guage and drive aswell ?i will make myself some DIY det cans which should help, ive heard recordings of it and know it sounds like popcorn or marbles in a jar. what should i be watching for as a sign of knocking or dangerous operating tempratures with an egt gauge?
Im still unsure what sort of afr i should be aiming for i know richer is safer as more fuel cools then engine which when on nitrous has increased cylinder pressure which if overheated can cause det. I know toward 12:1 would produce the best power but am i taking the piss running 21psi and running at 12:1?
The 25 shot ive currently got is good between 2500rpm and around 4000rpm past that i cant realy tell that much difference as there is a shit load of torque from the turbo anyway. Ive got a rpm window switch and just run the nitrous between 2500 and 4000rpm as i didnt notice enough difference top end to warrant running it at higher rpm.
That all said it is pretty addictive and if i dont see the gains i want from leaning the ratio out then i can see myself stepping the power up as its so tempting! The next stage for me would probably be a fixed 35 shot running slightly on the safe side AFR wise or im also considering a controller and running a 25 shot that builds to around a 35-40. Other than ignition and fueling capabilites what engine hardware wise could let go ? Should i be worrying about the rods ?
If you want to run more gas, wind the boost down.
I'd not lean it out too much more, you're running high boost and gas. Leaner on lower boost would be okay I think.
EGT is useful to know how close to melting things you might be - but your ears are the best tool for spotting det.
Det sounds like loads of little stones rattling around in the exhaust manifold. Its easy to hear, you will definitly notice it, especially if its bad
I'd not go much beyond a 25 shot dude, it's easy to get carried away with giggle gas - I ran an 80bhp fixed shot on my 90bhp GT, that hit hard!
21psi and 25shot is what I ran, gave about 23bhp increase, and gob loads of torque - was funny!
Rich AFR is good, keeps things cool but also has the effect of slowing the flame front down a richer AFR can be thought of in a similar way to ignition retard in this sense except EGT reduce with a richer AFR and generally increase when you retard the spark.
From memory mine used to run 10.8:1 - the data logs are on a dead laptop. For the sake of gearbox/valves/rods I'd not go much beyond 25bhp on yours, should be a good 215bhp with it anyway!
Loads of fun, and sounds mad when on gas ;D
Also keep ontop of the plugs, I melted a set of W4DPO and then switched to NGK BP8EVX, had a bad lot of them off eBay but the rest have been fine. Nitrous will work ignition components hard the charge is clearly denser.
Keep going until you have snow forming on your throttle body ;D ;D ;D ;D
Ok thanks for the replies,
The egt sensor is around the £100 mark and it was more of a tool to help me detect det than anything else but if my ears or det cans will work best for that ill probably give the egt sensor a mis.
Would have liked to have seen what the 80 shot felt like in the get yoof i bet that was a hoot !
If i do run more gas say a 35 shot i take it would be safer/softer on drivetrain and engine componenets if i did so with a progressive controller, im aiming to break the 220bhp barrier on gas how much boost should i take out if i want to run more gas a couple of psi or more like 5?
You could defniantly tell the difference between on gas and not then yoof all the way through the rpm range ?? the only reason im considering running more is because i didnt feel a huge amount more torque
I wonder if there is something wrong with my system as i dont feel that much more torque, theres a bit more low down where you would usualy have a bit of lag. ill give it a good check over and may end up upgrading to a cd ignition as that may be why im missing power.
Yoof did you do the acceleration test on and of gas like from 40-60 timed of gas and 40-60 on gas or a smilar test if so i dont suppose you can remeber a ball park figure as to how much time you where shaving off?? Did you run the 20/50 jets then ? Did you do a spark strength test aswell ?
What's your bottle pressure like?
900psi got a bottle heater and a pressure switch works a treat.to keep bottle pressure constant ;D
checked that ive got fuel pressure and flow, checked ive got fuel and nitrous, checked activation to ensure wiring works which it does.
may my ignitions not up to it although its all new oem components that have been checked to give a 15mm spark consitantly, just odd as yoof ran standard ignition system with his no problems
set plug gap to 0.6mm aswell.
just for anyone intrested, had a fiddle around with this a bit more at the weekend.
I changed the jets to 50/20 to lean out the mixture at wot. got pinking as soon as i hit the nitrous so i changed the jets back still pinking hmm scratched my head and dropped the boost aswell still pinking pulled the plugs and the earth strap was white.
only thing i had changed was the plugs to bp8evx so i swapped back to the old plugs still pinking!!! last ditch attempt now and pulled a degree from the static timing set it at 5 degrees rather than 6. hit the nitrous no pinking just a smooth surge of power. it was completley different and had me grinning from ear to ear.
im more than happy with a 25shot although it works much better at lower rpms so im going to just use it low end between 2.5k and 4k to give it a bit more go may try a 35shot with less boost at santa pod when i next go but for now im well happy nitrous is very fun !!!
Good stuff ;D
Goes without saying but it's still fairly cold currently, if you're 1' away from knock then be aware in the summer you may need to adjust to compensate for atmospheric conditions (or lower bottle pressure)
yea definantly worth remembering. Tuning the nitrous was a good learning experiencr has taught me a little bit more about the effect of timing, temprature change, pinking, spark plugs and other little bits and pieces had fun whilst doing it aswell!!
I did notice when the nitrous "hits" there is an initial leaner period with afr around mid elevens before it leans out to low tens im hoping to cure this with nitrous pipe length meaning i can go a touch leaner on wot aiming for aroind eleven to be safe.
Amazing how much difference a degree of base timing can make, although this means i may make less power of gas, i have considered an msd ignition which allows ignition retard on gas only as a switchable option but seems like overkill for my application.
I can only assume that with 6' of advance and no gas when the temp goes up outside i may need to remove a bit of advance anyway.
seems like my motor is pretty det prone or on the edge anyway i assume this is down to a slightly overworked turbo and a compression rationl which is reasonably high.
I'm sure if you speak to Andy (once baby has popped out) he can do you another map with blanket retard on it, this can then be switched in cabin (up to 3 maps I think).
Meaning you can leave the dizzy alone, then flick a switch 8)
All PY motors hit knock limit before max brake torque, compressor/turbine sizing won't help this, and as you say a high CR (and fairly basic combustion chamber design) don't help. However with sensible intercooling, methanol/water injection and a decent map you can keep ontop of it.
You're now approaching 30bar BMEP - which is impressive for an engine with good road manners!