The V8 Owners Forum -

Is timing an issue with decent amounts of N20?

yup need to take some out
i was running stock ignition on 75 shot,
but i now run 150bhp shot gas and start taking timing out at 75 bhp 6 degrees is taken out by 150bhp

How do you do it? With the blower I have a boost timing module which just retards the ignition by a variable amount with boost, with nitrous there isn't anything to take a signal from as such, all the electrics know is how open the solenoids are, it doesn't know what size jets you have fitted. Its probably fine on a drag car with no on road requirements, but what if you want good driveability most of the time and nos only for now and again?

my nitrous controller has a retard feature,
gives a trigger output to the ecu and i set the ecu by how much to retard when the controller tells it too.

What controller are you using Tom? Or is this a fixed hit system?

The amount of timing you take out sort of depends on what static timing you have set in the first place. And what advance the dissy is giving on mech advance. And what CR you are using.
If you have a timing retard system that works on boost pressure. This may be all you need if its adjustable, depending on how much gas you want to flow.

I've got my 4.6 set to 8 BTDC static. Which is the setting for my old factory 130hp 3500. I only use 3 degrees of retard for a 250 shot. And I have twice forgotten to switch the retard in at all. The difference between retard and no retard was not really measurable in my times. Maybe 3/100ths of a second slower with no retard. But I'll try not to do it again. There no exact science. Just safe guidelines from the guys who supply my stuff. Which is the best place to start eh?

I use an MSD remote adjuster to delay my spark signal to the ignition module. And mine is an auto, so I launch at wide open throttle and then dont back off until I either go out of shape or cross the line. All my timing is in by 3000 rpm which is about 10 feet off the line. And I shift around 4000 rpm.

The most imprtant thing I do is get my car on a dyno so I can see what various settings do while my man watches AFRs so he can shut it down if I'm too lean or too rich.

Once I know the AFR's are in a safe place. I just fiddle with timing and boost control at the track.

The rule of thumb is 2 degree's of retard for every 50 hp of nitrous.
This will keep you in a safe zone for testing.

What pistons are you using?
What ring gaps have you set?

Perry

Haha no I'm not planning on using it on the blown lump Perry! Its just this big block I'm still weighing up for my next build, I'd quite like the car to be a sleeper (even though I'd love a blower like Adams Jago ) but nitrous will be a lot cheaper and easier, plus it'll be cool to have a genuine ARM switch in the cab

I'm still not sure between dissy and twin 4bbl carbs or electriceryonics though, I love the old skool big block tuning with 2 huge carbs on the top, but injection may be the way forewards and probably no difference in cost, thats why I was wondering about timing etc with the nos.

Hi Tom
If I can add my two pence worth.I run an MSD with an adjustable retard module in the dash so it can be tuned whilst at the track.
I beleive it will only work with an MSD ignition although I may be wrong.
The other thing to consider are cooler plugs for a big shot of gas so as to avoid detonation which is a no no for gas assistance.

Just admit it you want the ARM switch and a purge valve dontcha!
Cheers
P

"Just admit it you want the ARM switch and a purge valve dontcha!
Cheers "

I've got 3 arming switches on my console Tom!
Nitrous arm. Nitrous fuel system arm, and the bottle heater. Looks cool. I dont actually need a purge on my system if I keep the bottle pressure at 900psi. But you cant resist the little plume out of the bonnet just before a run eh

The MSD retard module works fine with my Mallory Hyfire AL6 unit.

Try B8ecs plugs if you only intend to run up to a 150 shot of gas. Over that you should try a set of C55R's which I use. These are great for road use with any CD ignition system and wont let you down on big shots of gas.

But you will find that you can use stock plugs if you modify the earth electrode for up to a 150 shot.

See told you I might be wrong!!!!!!
Three arming switches?
You just a show off Perry
What he does not tell you Tom is that he has three arms aswell just to work everything at once!
P

Nato style arming switches look cool mate

I've got 3 of the arm switched in the mx5 at the mo, 1 for ignition, 1 for fuel pump and 1 for vacuum pump (forgot about fan!)

It would be on a BB so more likely to squirt 3-500 gas than 100 I'm guessing for that amount I will need to retard, but for that amount I'l probably also want a controller which like Tony's will also have retard built in?

Timing makes a world of difference and if its not proper, I had problems with false plug readings and what I thought was lean pops but looking back I'm more confident in thinking I wasn't pulling enough retard.