Today I was wanting to give the 75shot a try with on my LD9. Well, per Zex and "other peoples" suggestion I went to retard the timing 4 degrees on my DIS 2. Well, I came to fine out that the MSD took a big crap on me. It kept kickin the rev limiter on at 3,000 RPM. Tried everything to fix it to no avail. I put the bypass adapter on the MSD so I could run stock ignition. Problem solved. I then started pondering the thought of trying the 75 shot with stock timing, of course I gave in...
I first got on too a clear stretch of highway with no traffic and hit the switch at 60mph, felt nice. A/F ratio (AEM UEGO) was sitting pretty at 12.1:1, everything sounded and felt smooth. I decided then to try a drag run. I launched the car at 2 grand and hit the switch as soon as I caught traction. The car shot to seventy as if I was being dragged by a 747... The A/F once again stayed deep in the safe zone at 12.1:1. After this run I started to question myself as far as if retarding the timing was needed. There was no knock and the A/F was in great range. The problems I had was the feeling of possibly losing traction at any given moment and the fear of spinning a rod due to the quick reving of the engine.
My question to all the gurus out there is: Based on my A/F ratio, why would I need to retard my timing? Is this step needed?
For the sake of knowing, here are my engine mods:
MSD Wires
External Coil Conversion
Stans Header
2 1/4 custom mandrel bend exhaust
O2 Simulator
Glasspack replacing CAT
Urethane Motor Mounts
Custom CAI Using Vibrant Performance Parts
2.3HO Pulley
Melling "Hybrid" exhaust cam
2.3HO Intake
62mm TB
Walbro 255lph In Line Pump
ZEX Wet Nitrous Kit (75 Shot)
TR6 Plugs
Royal Purple 10W30
<img src="http://www.hybridcav.com/images/whynot.gif">
^ANYONE?^
<img src="http://www.hybridcav.com/images/whynot.gif">
I pounded my car with a 75 shot and no timing retard for a couple years with no probs (NX wet kit). I upped it to a 100 shot and broke a piston due to detonation. Not sure if I was detonating pryor to the 100 shot judging by the look of the head and pistons. So either I broke due to lack of retard, or due to the stock fuel pump not supplying enough fuel for a 100 shot and going lean. Just a FYI, you can't always hear knock, so don't think just cause you don't hear any there isn't any. Good luck.
2000 Z
Well hey! If you figure out what's wrong with that MSD and fix it send that beotch to me because a 2200 DOES need to be retarded on a 75!
bballjamal@aol.com (hook me up)
N2O + Bolt-ons
= 220Hp/
250Tq
Coming Soon:HpTunersPro, EagleConnectingRods, WiescoPistons, 13sec2200
I still have yet to buy an MSD box to retard my timing. I've been through 3 bottles on the 100 shot with nothing more than colder plugs. Colder plugs are the key to running 75 or higher shot on stock ignition. I plan on going two heat ranges colder (NGK TR7, stock =TR55) for this season. Last year I ran mostly a 75 shot until the end of the season on TR6's. The colder plugs draws heat out of the cylinder faster, which is crucial in N20 applications, where cylinder temps, and EGT's go up fast. That keeps your pistons and exhaust valves happier.
Honestly though, I am pushing it with the 100 shot and no timing retard, but I would feel perfectly safe running 75 shot on TR6's for many seasons with no retard.
<img src=http://ourworld.cs.com/jwithspray/Jbeier_sig3.JPG>
I was running Tr6's in mine.
2000 Z
Could detonation really be present with the A/F running 12.1:1?
<img src="http://www.hybridcav.com/images/whynot.gif">
the knock detectors should catch any knock and retard before anything bad happens, its a fairly small shot still and your alright if you keep the a/f ratio where it is. I personally would like to see it around 11.7 just a tad richer but thats my safety margin. looks good keep on play'n!
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** Flat Broke Racing Inc.**
I think I will save up for a Programable DIS2, but run the stock ignition for the time being. I will say one thing, I lose traction periodically all the way through second gear... That is a freaky feeling. when I had my supercharged Dakota R/T I would not have traction till third, but since it was boosted the power levels stepped up per rpm so once I caught traction I never lost it again. Its wierd to hit the switch at 30 mph and lose traction and feel it periodically slip through the gears. That really displays just how powerful nitrous is. It also weird going that fast in a fwd... lol
I was running a 15.4 with a few mods and after the seaon ended I added a couple more that would have probably put me at the 15.2-15.1 area. With the 75 shot and my suspension mods I am hoping for a 13.9... That is my goal.. My Supercharged V8 ran that, I would love to match that with my cavalier...
<img src="http://www.hybridcav.com/images/whynot.gif">
run the stock ignition, but run ethonal blended fuel, it has alcohol in it and that will really help out with cylender temps
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** Flat Broke Racing Inc.**
on my car I have been using the 75 for about 28-30 bottles and have yet to run into problems -- all i have done is colder plugs (for nitrous anyway)
So I went out this weekend and had a chance to spray the 75shot 3 different times...
1st time= 40 to 90mph to show my buddy the difference... I thought he was going to cry..lol
2nd time= Mullet head in a early 90s Camaro meets me at a light and revs up.. Smoked him all the way to 80 when he finally gives.
3rd time= This is what I had been waiting for... A LS1 Z28, Turbo 240SX and Lil ol me.
We all launch from 30 to 40 mph. We stay lined up till around 70mph when the 240SX spools like a freakin beast and jumps a car lenght ahead of the z28 and myself. The 240 let off a somewhere around 85mph a little over a car length ahead over me and half a car length over the Z28. I was very happy to be able to hang with an LS1... I did not expect that to happen at all.
After this race I decided to call it a night and get home to inspect my plugs. I took out the first plug in cylinder 1 and found this:
<img src="http://www.hybridcav.com/images/Preign.jpg">
Obvious Pre Ignition.... I replaced the plug saturday and it drove just fine... I thank God I did not burn a hole through the pistion and that the valves did not get damaged. I am going to do a compression/leakdown test on all four cylinders to check for valve and ring damage.
Lesson learned:
Some people can get away with not retarding the timing 4 degrees on a 75 shot, some can not. I will wait till I get the Programable DIS2 before I go with the 75 shot again.
<img src="http://www.hybridcav.com/images/whynot.gif">
Ouch. What plug was that? That's exactly what happens when you try to run platinum plugs with nitrous (not saying you did). Try NGK TR6's (part # 4177)
<img src=http://ourworld.cs.com/jwithspray/Jbeier_sig3.JPG>
Those are TR6 plugs.....
<img src="http://www.hybridcav.com/images/whynot.gif">
doesnt mean pre-ignition, she was definatly up in the temps though. take a look down the white insulator of the plug. right now we're looking @ idle or low rpm range, to find out whats going on you not only have to look at the damage, but the rest of the plug itself. a sparkplug can tell a @!#$ load of information when read correctly.
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** Flat Broke Racing Inc.**
did you spray at low rpm? The lowest I would spray a 75 shot is 3000 rpm
<img src=http://ourworld.cs.com/jwithspray/Jbeier_sig3.JPG>
