Nitrous KA build

[traybore240]

Hey all. Im rebuilding a KA for use with nitrous. The nitrous wont be used very often, however I would like to run a 100 shot safely. What are the weak points in the KA with regards to nitrous? The current plan is mainly a stock rebuild... clevite bearings, felpro gaskets, cometic head gasket, ARP studs, stock pistons and rings. From what I have read the rings are normally what gets blown with nitrous, is there any better rings than OEM? Thanks.

[pregmantis]

I think you will be ok with 100hp unless you lean out. the pistons would prob be the first to go.

[naed240sx]

Wish I could help you. Funny story though, a local guy installed a 100 shot on his 240sx with a completely stock 180k ka in it. Bumped 2 seconds off the quarter mile time, and I believe it lasted at least another 10k hahahaa.

[TheOne]

i believe the fuel system is the 1 not capable of doin 100shot, people have ran 75 shot safetly.

the pistons are the weaker link though.

[KADreams]

I am about to run the same shot on my built motor.

Specs:Supertech 9:1 Pistons (90mm overbore)Cometic MLS HeadgasketARP Rod BoltsARP Headstuds3-Angle Valve JobNissan OEM Bearings

Nitrous System and Supporting Hardware:

Zex Dry KitMSD Digital 6 IgnitionMSD Blaster SS CoilNGK Plugs (1 Step Colder)MSD Window SwitchWalboro 255lph Fuel PumpNismo Adjustable FPR

This will also require dyno time to tune the fuel jets to produce an optimal AFR.

[Chezedik]

May want to get the rods shot-peen'd. With good tuning I bet you could run 150-200 shot on stock setup. Would have to be wet of course. Something like the Venom setup would help a lot in that regard.

[SeVa-S13]

Why run a dry kit? Basic wet kits aren't much more expensive.Not that dry kits as a whole are a bad idea, I just prefer wet.

[KATwo40]

I am about to run the same shot on my built motor.

Specs:Supertech 9:1 Pistons (90mm overbore)Cometic MLS HeadgasketARP Rod BoltsARP Headstuds3-Angle Valve JobNissan OEM Bearings

Nitrous System and Supporting Hardware:

Zex Dry KitMSD Digital 6 IgnitionMSD Blaster SS CoilNGK Plugs (1 Step Colder)MSD Window SwitchWalboro 255lph Fuel PumpNismo Adjustable FPR

This will also require dyno time to tune the fuel jets to produce an optimal AFR.

If you'd use high CR pistons, you'll see MUCH more performance. Nitrous cars LOVE high CR.

I'd look for some 10:1 or higher.

[Aries]

The stock fuel system is the weakest point in a nitrous build. You really should upgrade your fuel pump to a 255 lph Walbro (or something similar).

The first thing to go in these motors is the rings, followed by the valves as the remains of a sparkplug pass through them.

99% of the time, there are no problems running nitrous, but that other 1% is why they make safety equipment like RPM activated switches, and fuel pressure safety switches.

If you follow the directions in the kit, and have the fuel pressure and constant flow to support it, a 100hp shot is no problem on a stock-ish KA. I certainly would have a nice free flowing exhaust though since the nitrous produces higher exhaust temperatures and you will want those out fast.

[KADreams]

The first thing to go in these motors is the rings, followed by the valves as the remains of a sparkplug pass through them.

What plugs do you recommend for nitrous use?

[Chezedik]

anything 1 step cooler.

[Aries]

What plugs do you recommend for nitrous use?

Personally, I have found that NGK VPower TR6 sparkplugs work very well in nitrous KAs. You must be sure that you get the ones WITH the crush washer though, as the ones without will leak compression.

Basically anything 1 step colder will work well with a 50 - 150 shot; however, you do not want the multiple tip plugs like Bosche or Splitfire.

[traybore240]

Thanks for all the great info guys. Fuel pump is already done. MSD blaster SS, MSD 6AL, and MSD wires are all ready to go in. Ill definitly look into shot peening the rods. So ya'll would recommend aftermarket pistons rather than OEM? Oh, and exhaust is already on, only thing left there is a high flow cat. Is there any stronger aftermarket rings? Another question... What is an engine core? I found a KA from a 95 for $100 at a local salvage yard, and the listing says "2.4L/CORE ." Thanks again.
Modified by traybore240 at 2:16 PM 4/3/2006

[Chezedik]

1) a core is your old motor. They will use it for rebuild or scrap metal. It is common practice when you buy certain parts to be charged a core charge, that is refundable when the previous is replaced. 2) I think you would be best served with SOHC pistons, the high compression will help your power and as long as you use a wet shot with good gas when you shoot, you should be fine. Also, you may consider a JWT nitrous daughterboard or some sort of other timing retard for when you juice. I think MSD makes one too. Forged would be good, but I think it is unnecessary so long as you are realistic in your nitrous usage and get a quality setup. As I have said before I recommend Venom for it's tunability.4) Your rings will NEVER be an issue if you can control detonation and don't run pig rich when you shoot. You want to be rich, but be careful with the jetting so as not to wash down the rings.5) Have fun.

[traybore240]

Thanks. Detonation is what Im worried about with the high compression. The highest octane gas around here is 92.

[Chezedik]

That is where the JWT daughterboard comes in. It runs optimized timing for the 11.7, then when you trigger the Nitrous solenoid, it backs timing off, to prevent detonation. Once the microswitch is released, it reverts to the previous timing map. Really very ingenious, and if you are going high compression with spray, there is no better mod. Also, the high compression will allow you to really take advantage of NOx. Without it, your 75 shot will only be about 63, etc.

[halnfl]

for the longest time I ran a nx wet kit on my car, just had basic mods, 1 step colder plugs and knocked my timing down to 17, ran a 125 shot for almost 2 years and lots of trips to baytown, this was on a engine with over 100k.