Engine is tuned NA for H/C. Does it need a retune, for A/F ratio with wet system or is timing retard and colder spark plugs enough?

Dedicated fuel pump will be used for the wet system, 200-250HP single nozzle system.

 

Ttt.....

 

If you dont consider pulling 6-8 degrees of timing in your WOT cyl air mass table a re-tune, then no.

The car should behave identical as the spray should only hit at WOT. I have noticed that after spraying a 200 wet shot, my car will run like **** for a little while and then it will clear up. Best that I can figure is that the fuel in the fuel line (from the solonoid to the jet) is still dripping into the intake causing it to stumble and run bad at idle until it all drains out.

 

Anything that can be adjusted without affecting NA tune, I don't consider it a re-tune. Using Timing Retard device to pull timing with nitrous activation will not affect NA tune and is not considered a re-tune.

A/F ratio adjustement will affect NA tune if it has to be done with nitrous. I am hoping Wet system will keep correct A/F ratio with just dialing the nitrous and fuel jets.

 

Be carefull with those timing retard devices. Specially when spraying 200+. I know 2 people that have used them and both of them worked for a while and then started to cause problems. One of them wiped out my buddies 402 as it decided to stop working on a DP 300 shot pass. Detonation destroyed #7 plug which in turn bent a valve, tore up the piston and knicked the cylinder wall. He will never try it again.

 

We are actually working on something that will work like a flip chip to switch back and forth between NA and NOS passes. The idea is to tune the car with the nitrous tune (low timing) and then wire up some sort of A/B switch that will toggle between the actual IAT sensor (for NOS) and a resistor that will read 40* IAT. The PCM has an IAT spark modifier that will allow you to add timing at a given IAT. Since we live in Florida, we will never see a 40* IAT temp once the car is warmed up. So when running on motor, you flip to the resistor where the computer will add however much timing we want for an NA pass.

 

Thanks for the heads up. I think a spare PCM with nitrous tune is a good investment.

Also, I think I read some are using two tunes with one PCM, activating the nitrous tune using a PCM wire connected to nitrous activation switch. How is that?

 

Its done with with EFI Live using CO#5. CO#5 had nitrous tables in the tune. You need to run a wire to pin #56 pn the red connector and the other side to a switch and ground. It works very well, I have used it on several cars including my own.

 

What's CO#2? Can you explain more. Can this be done with HP tuner or Tuner CAT?

 

Bmp, I just heard about the EFI stuff the other day and was wondering the same thing. Can it be done with HP Tuners?

 

No Hp doesnt have a nitrous operationing system. EFI Live is the only one that I know of that has one.