Trigger for water meth

I'm trying to come up with a solution for my detonation issue with my nitrous 200. When the nitrous system is on, my water meth system is triggered by the full throttle switch and it doesn't detonate. While running on just the motor while crusing at lower rpms, it starts pinging. I was thinking that I could either use the 0-5v output of a knock gauge, or use a vacuum switch with a RPM window switch. What would be the better activation?
 
I'm not running vacuum advance. My total advance is set at 36* initial is 16. My distributor was giving me inconsistent readings of slightly over 40*, I found that the vacuum advance lever was loose on the plate and it was moving around. I permeantly locked the vacuum advance. I'm going to lock the distributors mechanical advance and upgrade to a msd programmable system soon. My cranking compression average is 215psi. I have been told that with my 280 110lc cam that my compression ratio is over 11-1. When I originally did the math for my compression ratio, it should have been 10.5-1. I believe that when I built my new short block, the deck must have already been resufaced. I could have corteko make a custom copper gasket to lower the compression and help transfer heat or retard my cam a little, but I would loose potential power. I already have a water meth system installed for my nitrous, I'd rather just have a secondary trigger for street use. The engine does not ping in cooler weather.
 
To answer your original questions.

If you control the water/meth from the knock sensor it will cycle on and off.
When the knock sensor sees detonation it will turn the water/meth on which will stop the detonation and the knock sensor will then turn the water/meth system off and detonation will begin again and so on and so on.

When you are cruising the vacuum is relatively high so at what point would you have the water/meth system come in at?
If you set a vacuum switch above that point the water/meth would be on most of the time.

You have the correct solution with the programmable MSD 6AL-2 (Part# 6530).
You can keep a high initial timing, pull some timing out at low rpm cruise and put the timing back in later.
 
Do you think this could just be fixed with tuning? I have always been told that 10.5 is the maximum compression for a cast iron head. I believe that the programmable msd has an input for use with a map sensor for boosted applications. I found this on eBay, it has a 0-5v output. Maybe it can be used in place of a map sensor to automatically pull timing instead of triggering the water meth? Just as a failsafe. https://rover.ebay.com/rover/0/0/0?mpre ... 3335180987

Or should I not even bother?
 
The Ebay knock gauge does not come with a sensor.
You need a sensor specific to your cylinder bore which determines the frequency of the detonation pulse.
Each knock sensor is tuned for a specific frequency range.

You can temporarily turn your distributor to see how much timing needs to be taken out to eliminate the detonation only during part throttle cruising.
Then come up with a plan to tune it out.
 
Do you have a cold air intake where you pull air in from in front of the radiator?
 
Last I remember you have 3 K&N type air filters sucking in hot engine compartment air.
If you could make a box around all three and run a 4" line to take in air from behind the grill or something similar.
 
Under part throttle are you running only on the center carb or all three?
Do you know what the air/fuel ratio is during part throttle?
 
It is a non progressive setup. Through the whole RPM range, it is now about 12.5 at idle, 13-13.5 part throttle and 12.5 crusing, slightly leaner at full throttle at about 12.5-13. it drops to about 11 for a sec if I gas it.
 
It's certainly not detonating due to lean conditions.
I would pursue the cold air intake next.
It might save you from having to make changes to the timing.
 
I'm definitely going to look into it, but I'm still going to upgrade to the programmable box. I did an experiment on the distributor when I was locking out the vacuum advance. I already have a 3stage retard that I use to pull timing for when the nitrous is active. I locked out the distributor and tried to use the 3stage basically the same as I would with the programmable box. I set 36* advance locked and set the retard with pills. I was only able to take out 7* with the pills that I had, so the initial timing was way too high at 29*. I backed off the distributor to drop it to 18*, but now I didn't have enough total advance, but I did notice that the timing was rock solid. My timing mark, jumps around a little with mechanical advance, but solid when it's locked. I figure that a locked distributor will have the same effect with the programmable box, but I will have a proper advance range.
 
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