I am running nitrous and I'm concerned

amctmg · Post by **amctmg** » Thu Mar 17, 2005 3:15 pm

this datalog was the result of 02 ep3 w/550cc injectors, civic si tuned high octane calibration with unmodified fuel trim or tables. I don't remember the exact retard or fuel enrichment settings but they were between 5 and 10 degrees retard and 1000 to 1800 fuel enrichment ( I kept increasing the setting in hopes to remove the knock but no luck.) BTW I was running in open loop I believe.

edit: this was with stock plugs that I replaced later that day with the zex, one of the plugs had the insulator broken on the inside and the electrode had a dimple on it

Post by **Spunkster** » Thu Mar 17, 2005 3:27 pm

You must also post your calibration file so we can see what you have done.

amctmg · Post by **amctmg** » Thu Mar 17, 2005 3:46 pm

calibration added to first post.

edit I was wrong, this is the cal. I used for that datalog.

the first cal I put up was the one I used at first and saw the heavy knocking so I thought it might be safer to use the factory cal which is this one but same result

Post by **Spunkster** » Thu Mar 17, 2005 5:35 pm

From looking at the datalogs, it looks like you were using the first calibration you posted with that datalog.

If you keep removing timing and are still getting knock readings, you may be getting false knock. You may need to readjust your valve lash, making sure to adjust it between the valve stem and the rockerm not the roller and the cam.

Also between 4 and 6 degrees of timing retard should be adequate on most nitrous setups, but do not take this as gospel truth since all cars are different and the tuning needs of each car must be addressed.

amctmg · Post by **amctmg** » Thu Mar 17, 2005 7:33 pm

I checked my valve lash about 10k ago and it was well within spec

the thing that bothers me the most is I ran the same setup last weekend with the 75hp jet starting with 4 deg. and 1200 fuel and gradually leaning it to 700 fuel before having a single knock but the bottle pressure was always below 700psi. This time I heated the bottle up to 1000psi and started out with 4 deg and 1000 fuel then bam 50 knocks per second but ungodly power.

I read somewhere that the optimum a/f ratio with nitrous is 8.5-9.0:1 but I talked to a guy today that said as long as it stays below 12.5:1 your good. Any insight?

also, are there any cam angle adjustments that might help with nitrous? even if it has to be a drag strip only calibration.

thank you

CivicVTi · Post by **CivicVTi** » Fri Mar 18, 2005 2:45 am

12:1 is ideal with nitrous (max 11.5:1). Below 11:1 you can get misfires.

amctmg · Post by **amctmg** » Sat Mar 19, 2005 10:10 pm

I'm thinking that maybe the problem right there way too rich

I ran it tonight with the 75 shot 4deg retard 500 fuel and the bottle was at 650psi and I only logged 1 knock but I've made a few adjustments a few days ago to the fuel table after datalogging and seeing I was way to rich. I also trimmed the fuel 6% overall.

hopefully I can dial this thing in with optimum pressure, I don't need another paper weight