i have a h23 prelude, just recently finished the built. on the dyno the spark kept blowing out at 13 psi so we left it at 12. now only after driving for awhile it will blow out. i have done everything i can think of to try and stop this but no go. i have changed rotor, cap, coil, distruber, plugs and wires. the ignition setup includes

bkr7e-11 gapped .28
ngk wires
msd coil (new) tried 2 new ones

If anyone has any ideas please let me know. thanks in advance.

 

Have you examined the plugs? At your power level, I'd use some NGK 4554's instead of those 7's

 

the plugs look alright they have white with very light brown showing up. ive never heard of the 4554's. are they cooler plugs?

 

or just get 8's, but that doesnt explain why you're losing spark at only 13psi with that tight of a gap. Maybe an ignitor going bad? i run a 28gap on my DD @ 24 psi, never any problems

 

spark blowout can occur for a few reasons.. Weak ignition system, not enough timing, too rich of a fuel mixture, to big a spark gap for the combination of the above mentioned.

What are your AFRs? How much timing are you running? How old is your ignition system? At what RPM do you start getting missfires? I often run plug gaps down to .016 on boosted cars. Most honda ignitions are 10+ years old already.

 

The psi level is irrelevant as it doesn't really matter at what psi he starts blowing the spark out, but at what power level.

THe first thing I'd do is make sure the coil and igniter are in good condition. MSD coils are good replacements and it's the only thing I'd recommend on our Hondas. If you replace your igniter, put some dielectric grease on it as they take in A LOT of heat and is the main reason(asides from age) as to why they go out often.

 

Actually spark blow out is very much related to boost pressure. As you increase the density of the compressed mixture it becomes more difficult for the spark to jump the gap.
This is also why having too much timing retard can cause missfires, the closer to TDC you are the more compressed/dense the mixture is.

Again, just try gapping your plugs down.. I'd go straight to .016 gap and call it a day, saves you the hassle of having to re gap a bunch of times. And I'd recommend a #8 heat range plug either the 4554 (non projected/non resistor copper $12) or BKR8EIX (resisitor/projected/iridium $35) Occasionally the 4554s will cause electrical interference with some plug wires and coil setups so get you some NGK plug wires if your gonna run the 4554s. Otherwise if you can afford it, run the BKR8EIX Iridiums.

 

Yeah but would his spark blow out at 13psi on a 14b as it does on his current turbo? Probably sooner don't you think? That's what I was getting at. Guess I just worded it wrong.

 

13 PSI is 13 psi regardless of turbo size. The smaller the turbo the less dense with oxygen the mix will be at the same pressures due to higher temps cause the mix to take up more space..

Its either too rich, ignitions too weak, not enough timing, or he needs to gap the plugs down.. Not all engines run the same, I've had stock ignitions do 750HP & 28PSI and I've had MSD ignitions not wanna spark past 14PSI.. Gap the plug down, problem solved. Granted your burn somtimes won't be as efficient with a smaller gap depending on the head/motor, but the losses are minimal when your talking about 350+ HP. .016 and be done with it.

Also the plugs will erode and ungap themselves overtime depending on how much you beat on it. So you will have to regap every so often.

 

thanks guys i appreciate the help i will regap down and im having my tuner look at it again to see if he can fix anything with the tune. ill keep diagnosing and relay my results

 

ok talked with a tech at ngk he told me that since i was running the bkr7e-11 that running the gap down to where i had it was too much. he said the changing the gap .008" will take the gap out of parallele and will hurt performance more than help so told me to go with the bkr7e which has a .032" factory gap. well switched to them and help a little bit but still goet blow out every now and then. will post up again when get more progress.

 

..... dude.. the tech guy at NGK probably never tuned a boosted motor or worked on a race car.. If you do what I said you will not have anymore blowout issues. Getting the ground strap out of alignment is not gonna hinder your performance any more than a missfire lol.. Just try what I said and I bet you $100 it works.