NITROUS OXIDE ( nos / n2o ) advice forum

HI

I hope Brian is reading this.

Went to a rolling road day on Sat @ PE. THe car not been runing ok lately, brand new plugs and leads and cap and rotor arm( non modified arm). But as soon as i was hitting 20psi, i was missfiring and loosing power. Checked everything and finally found the culprit. The plug gaps were std 0.7mm and had to be narrowed down to 0.5 for the car to run perfect. Should have thought of that earlier. Anyway to cut the story short, went on the rollers first w/out the noz, and the car didn't missfire. So for the measured run set the car up( only 25hp jet) and got it to activate to full power within 2 seconds. The car had one small missfire @ 2k revs and then everything fine all the way to 7200revs. Measured hp is 302hp. So i am sort of pleased with this speacially that the cams aren't dialed in yet. But noticed that at the top end the car is running slightly richer that it should be.

So now its time to move to the next step: 75hp jets or maybe 100hp?!!! Considering that the head is sorted(polished,flowed and ...) i am thinking about maybe sticking some leaner fuel jet in there. I don't know what the std jet sizes for 75hp is, but i thought maybe one size smaller for the fuel? with 2:1 ratio rule, that makes it 75noz to 40fuel? so what about 75noz to 30fuel?

THe car is a calibra turbo

Brian, do you fancy doing some tests? Find out which mixture is the best?

Cheers

Three comments;
1) what was the power without nitrous
2) you need to improve your spark strength if you need to reduce the gap without gas to get a reliable run
3) go up in steps of 25 bhp no more.

Regards

Well here r 3 answers:

1) the power w/out gas has never been the same as i have never had the car runnig properly or dialled in. The weather has been diff all the time. Last time i had a rolling road it was 270hp w/out gas, but that was at 15psi as the actuator couldn't hold the 20psi i wanted. The time before that, actuator was still new so it held about 18psi and pushed 305hp. So as you see it has been all over the place.

2) as for the spark strength and the gap: the std power for the callyT is 205hp, @0.8bar and 0.7mm gap. My cally has been slightly modified, so its runnig a bigger turbo and 20psi ( thats about 1.5bar) boost. So the gap HAS to be reduced as it has so much boost.

3) So u suggest the next step of 50hp? what combination of fuel/nitro jets is that?

Cheers

50bhp jets are 100/50 or if thats to rich maybe 100/45 or 100/40
im running 100/40 and when i had 100bhp jets in it was 200/80
im sure 100/40 is still rather rich, but i guess all cars are differnt and probally depends on fuel and nitrous pressure

hi

on the 4.5 reg i was using 3/1 ratio (60 fuel 20 nitrous), *this is just a guide naz*

do you have a printout of your RR run you can scan in please or can you at least describe the nitrous run compared to the off gas run?

when did the operator hit WOT?

you are welcome to come down to me to upgrade to 100bhp (after testing 50 and 75) as i know i can get a decent running calibra up to that stage in a day or less

regards, brian

My cosworth used to misfire, after fitted colder plugs, l fitted a high performance coil and changed to better plug leads,which helped providing l cleaned the plugs regularly.

I have scanned it, but don't know how to attch pics here?!!!

As for with and without run, i am afraid i can't do as only graphed the with gas run!!!

Cheers

email to beast@colorcon.co.uk ill upload it from there or use www.imageshck.us

i would have been at the RR myself but have now deserted that site (clubcalibra.net)

i notice he says he has non modified rotor
wouldnt that be a good nest step??

i guess he knew we was going to say that lol

BTW Naz you could also do with changing the injection point to the boost hose as this will shorten the hoses by quite a bit and allow the mixture to mix better before reaching the cylinders

yes now i think about it your right

sorry about the late reply.

Well here you can see the graph. As you see about 3k, a miss fire which bugers the whole thing up and then its start from bloody scratch. Recon if it hadn't missfired then it would have hit 320 roughly.

Cheers

I guess you are using a stock ECU, therefore getting the overfuel 'cooling' as any turbo car has built in.

Also just because you are seeing 1.5bar of pressure in the inlet, it shouldnt mean you need to close up your plugs. It is just an indication of how restrictive your engine is, the turbo pumps air, the boost is the result of the engine not being able to take the airflow in.

Which turbo are you running ?

Sounds like the ignition system isnt tip top, try Irduim plugs with OE gap and a grade cooler. Maybe the coil is getting lazy with age.

As for the jet ratio's i wouldnt worry about getting the top end right, just ensure you dont run lean ever !

Hi

Yeah i am using stock ECU, but with diff chip. They called EDS Phase chips, the one i have is PII. Supposed to run 260hp and about 22psi overboost and 17steady. BUt i am not using the electronic boost controller anymore as my actuator is uprated and throws the measurement out the door. Using a MBC device instead and that elminates the overboost anyway. I am running about 20psi steady.

AS for the plugs, used to have Denso IK22, but the tip kept falling off and causing me grief. So never Denso again.

So instead using NGK platinum at the moment. Maybe get NGK irridium at some stage in the future.

As for the ignition, yeah i think its a bit had it, stock coil and amplifier. Am thinking about getting aftermarket igintion system but its in the list at the buttom at the moment after bigger brakes and then a mgt system!!!! When you on a budget its hard!!!! So come on my lottery ticket, bring me some money

Turbo wise i am running a GT28 roller bearing turbo in a T4 housing. So to be honest the std ECU is no good and i do know that, but when i get to change it, thts a diff ssue.
Cheers

The Phase 2, is that the chip, intercooler and 3.5bar fuel regulator ?

But as you know you are running an engine with possible weaknesses, i would be very careful with the nitrous.

As for you misfire, it could be due to the GT turbos spooling up quicker, and the ignition system finding it hard to keep up.

And 3.5bar fuel pressure, may mean a smaller fuel jet can or needs to be used.

the operator triggered the nitrous at around 1100rpm.....it was too early for the ignition to cope on your currant ign system, ill bet it felt more powerful on the way there than it showed on the roillers eh!

leave the jetting for the moment and get the rotor arm mod done, i have a bosch red top coil for sale if you are intrested, it fired 22psi plus 145-165bhp of nitrous on progressive with the rotor arm mod, £30

so you need to...

reposition your injector to the silicone pipe
shorten the length of the lines to under 12 inches from pulsoid to injector
do rotor arm mod
test coil and leads for resistance (also clean them!)
in future ask the RR operator to hold back from WOT until 2800-3000rpm (for best results on the RR)

regards, brian