i just threw my car on the dyno on my built 9:1 turbo ready motor who put down 160whp 120 tq. I have a gsr block and b16 head. I have a dry 75 shot zex kit and threw down 238 whp and 211 tq at 6k bc at 6k i burnt a valve and we let off. What do you guys think could have caused this. I am replacing the valves but wondering if i can still run the same shot without burning anything else. i was tuning on a vafc and was at 1100 psi.

 

You need something to control your ignition timing-- VAFC doesn't do the job, and can even advance your timing (which you really don't want with your setup).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicsi13 &raquo;</TD></TR><TR><TD CLASS="quote"> What do you guys think could have caused this. ( </TD></TR></TABLE>

Two basic candidates - either you went lean or you had too much timing. What does the plug look like (or is it toast)?

 

no we made it rich as hell and plug number 2 was black as hell, the other ones were fine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ccivic &raquo;</TD></TR><TR><TD CLASS="quote">You need something to control your ignition timing-- VAFC doesn't do the job, and can even advance your timing (which you really don't want with your setup).</TD></TR></TABLE>

he's totally right, you probably be better of with the shabby raise the fuelpressure thingy. the vafc just tricks your computer into thinking it needs to be on another part of the fuel map. the problem with this is that it also puts out the corresponding ignition timing. that can be/is very bad!!!

advancing your timing multiple degrees on all-motor can result in the following: more power, knocking or eventually a hole in your piston.

advancing your timing multiple degrees on nitrous-engine can result in the following:
meltdown (your lucky you burnt a valve )

fuelcontrol with vafc is gambling with your timing

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicsi13 &raquo;</TD></TR><TR><TD CLASS="quote">no we made it rich as hell and plug number 2 was black as hell, the other ones were fine.</TD></TR></TABLE>

Then its too much timing.

 

2 degrees per 50 shot is the general rule. I ran 100 on stock motors every weekend for over a year...never had a problem. Use the zex setup as it requires...make sure your fuel jet selection is correct and retard 2 degrees at the distributor (the right way, so the ecu doesn't compensate). A 50 shot can be done with NO timing changes, but thereafter retarding is necessary....2 degrees per 50.

1100 psi is pretty high too....how did you get it that high? Generally the jets are "calibrated" if you will, for 900 psi....somewhere around there I can't remember exactly...1100 is high though for sure. The pressure relief gives at like 1200.

 

[QUOTE=RC000E] 1100 psi is pretty high too....how did you get it that high? Generally the jets are "calibrated" if you will, for 900 psi....QUOTE]

i have a bottle heater with a pressure sensor that maintains pressure at 1100 which i set it at.. i think im going to disconnect the vafc for spray and apray the 75 but at like 950. do you think il be safe with a 3 degree retard timing. ???

 

The plugs were probably black from when the nitrous was not being fired.

If you burned a valve it's 95% chance you ran lean.

Why not do the easy thing and run a wet shot?