Nitrous Tuning

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roccodart440

roccodart440

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I bought a NOS system for my car this winter. It is a Nitrous Express Trinity Plate System with a S.A.F.E Fuel System.

For those of you unfamiliar with this kit it is a HVH Super Sucker spacer that is plumbed for nitrous. The SAFE system is an independent fuel cell with race fuel (114) and it's own pump and regulator that only feeds NOS system.

My questions are as follows.


1. What is the MAX that can be put on a 440 that has forged pistons, rods and crank? It also has a nitrous grind cam in it.

2. What plugs would you run?

3. My timing right now is 34-35 total. How much would you retard the timing per added nitrous considering I'm already 3 degrees retarded and running race gas with the nitrous.

http://www.nitrousexpress.com/60541...ystem-stage-6-100-500hp-with-10lb-bottle.html
 
The amount that's safe depends on what it makes NA, the machining, the fasteners, the parts, and the tune. Assuming stock rods and crank and the typical 450hp NA - I'd limit it to 300. A good progressive controller could raise that a bit. The old school retard is 2° for every 100hp or for extra safety go 3°/100hp. As the system gets bigger the plugs are more important, as are the fuel and bottle pressures. 400-500 is a big hit in one shot on small tires or stock suspension.
 
moper said:
The amount that's safe depends on what it makes NA, the machining, the fasteners, the parts, and the tune. Assuming stock rods and crank and the typical 450hp NA - I'd limit it to 300. A good progressive controller could raise that a bit. The old school retard is 2° for every 100hp or for extra safety go 3°/100hp. As the system gets bigger the plugs are more important, as are the fuel and bottle pressures. 400-500 is a big hit in one shot on small tires or stock suspension.
Click to expand...

I was thinking 250hp shot so we are in the ballpark.

I have a progressive controller.

The 2 degrees per 100hp or 1 to 1.5 per 50hp is about what I was thinking as well. I was just wondering if I should take into consideration that I'm at 34, not 38?

WHat plugs? Or at least how much colder? I was thinking 2 steps colder? WHat about reach? .
 
What's the engine/car package again?
I've always understood that the goal is maximum cylinder pressure at the right piston/rod/crank position with no loss of combustion control. More advance can cause the cylinder pressure to go too high too early which really stresses the engine components and also causes a lot of power robbing. Hence my question about the engine/car package. IMO the retarding of spark has to do with that rather than avoiding detonation. Detonation comes from liquid fuel (unsuspended) which is much more likely to burn in an uncontrolled fashion in a nitrous engine.
I would go 1 step cooler for each 100hp depending on the head material, chamber design, and ignition. I'd also suggest you might want to give Monte on Moparts a PM shout. He is THE sharpest nitrous guy I've ever known and can get you in what I'd consider the best place to start. I plan to buy the entire system for my race car based on his recommendation. It's early in the season so he may be able to answer you.
 
Engine is a 440 in a 69 dart. 160 cranking compression. If you want more specifics I have them.
 
I don't recall the exact degrees atc the compression pressure peaks at, somewhere between 1 and something. the more compression your motor has the more timing you have to remove to keep the pressure peak the same. say a 14-1 motor has to remove say 8 degrees for an 250 hit but a 8-1 motor may not need any timing removed. plug reading is your best bet on figuring that out.
 
This is a 10:1 or 10.5 engine with 160 psi cranking compression. I was thinking of pulling 10 degrees out for the 250 shot as a baseline.
 
Head type? Camshaft specs? NA horsepower level? 10° is a lot for 250hp but it is safe. Best bet is making passes - read the plugs - see what it likes. Also make sure you've free-flow tested the plate to set the nitrous fuel pressure, and that the bottle has a gage so you can keep the pressures consistent.
 
on a 100 shot you could get by with 36 degrees if 38 is best motor tune:D and good gas as long as the plug read is good then go 2 degrees every 50 which would take you to 30 at 250, but if it were me id take it to 28 on the first pass with a progressive controller(will be easier on parts and have better times once tuned correctly) then check the plug read and you may be able to bump up a couple of degrees for best times , champion makes some good race plugs you have to cross some numbers or call mrl, hughes or imm and get from them, once everything is set with a nitrous cam and convertor hold on, it will make some passes, from my nos experience you will get the most gain out of around the first 150 hp then gains will decrease some, but testing will determine what shot and progressive settings works best, a lot of trail and error , good luck
 
moper said:
Head type? Camshaft specs? NA horsepower level? 10° is a lot for 250hp but it is safe. Best bet is making passes - read the plugs - see what it likes. Also make sure you've free-flow tested the plate to set the nitrous fuel pressure, and that the bottle has a gage so you can keep the pressures consistent.
Click to expand...

Heads: Eddy RPm heads
Camshaft: [email protected], .528, 112lsa


Thanks 345
 
Just for some added info here, ran my '69 Cuda back in 1990 with a stock 10.3:1 440-6 bottom end, 906's, big .650/290@/50 solid cam so Dynamic was probably crap. Back then we had 4 star leaded fuel, approx 99octane?....ran it at 38 total n/a.

Big Shot N20 plate kit, seperate blue pump and 1/2" line for N20 fuel alone, 5psi
Hit it off the line, kept timing at 38 total, 175hp jets. Plugs NGK B7S, no tipping, all ok.

Car ran 10.7 n/a at 484hp wallace calc....went 9.96 with = 600hp, so just under a 120hp increase from the 175 jets which is approx the mark could've perhaps tuned it a bit better.
 
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