Mudflap

Hey guys, now that I've had the Vortech on for a little while and I've had a chance to drive the car, I have a question about A/F. I've got the AEM wideband.

Initially the car was running stock plugs (the colder ones were on backorder) and the shop as well as myself observed an A/F ratio of 11.3 - 11.5 ish at WOT. I installed Brisk plugs on Wednesday, and now I'm observing the A/F go to 11.0 at times at WOT. What do you guys think of this?

Also, when I let off the gas quickly at WOT, I noticed the A/F gauge goes to 10.0 for a couple seconds. Is that normal?

Sorry for my nooby questions, lol.

moosestang

My fuel pressure spikes to 70+psi when I shift gears at redline, so that might explain the rich mix when letting off the gas quickly. If you think about it, you are quickly shutting off the air supply and have a lot of fuel going in, so naturally it's going to be rich for a moment.

I'm not sure about the plugs. My A/F was 10.8 at the richest point when I had the car dynoed.

Mudflap

Yeah that makes sense. The only change to the car was the plugs...

Simon1

You could switch plugs back and see what happens. You definately are leaving some HP on the table at 11.0. Definately want to lean it out slightly to the 11.4-11.8 range.

10.0 on a qucik decell is just fine as long as it doesn't stay there.

mygt500

Though an A/F ratio of 11.0 is a tad rich it is acceptable and IMO helps safe guard a little more in the long run. Moosestang is right in his explanation....as it just makes sense

I had an a/f ratio of 10.9 at WOT at about 5500+ rpms and my tuner explained it the way Moose did. But I had to get it leaned out a bit as the 60# injectors were causing cold start issues in the cooler months of the fall. Now the A/F ratio varies from 11.3-11.5 and she starts and runs great (added 10 rwhp too-like simon1 mentioned above).... no worries on your end.... just lets you know the fuel pump and the boost a pump are doing the job they were designed to do!

Mudflap

Cool thanks guys! I would say it is usually in the 11.0 - 11.5 range during WOT, I just had not seen it go to 11 until the colder plugs went in. When I let off the gas it'll hit 10 for a maybe a second or two, then creeps back up. Around town its usually at 14.6~. I don't feel compelled to have Brenspeed do anything to the tune, because as mygt said, I'd rather have a bit of a safety buffer there. Sounds like everything is working great!

Simon1

11.0-11.5 is just fine. If you want to run on the ragged edge you push it closer to 12.0.

My motor is built so it may run slightly different.

Just on a side note:

I'm currently doing some tuning on my car and it's on the rich side with a 100 oct tune at around 10.4 on WOT in 4th. It makes around 14 psi and spins the DRs in 1st, 2nd, 3rd and 4th sometimes. Talking to the tuner, he said when he leanes it out to the 11.8ish range I will gain another 50+ hp. Wow. I can't imagine. The difference in 100 and 91 is dramatic. I make 200 rwhp more at around 3500 rpms compared to the 91. For those who go to the track and have access to a good tuner it's money well spent.

Mudflap

Cool man, that thing sounds like a blast. I can barely keep mine straight at my power level, so yours must be nuts!

turbo463v

you want to keep your A/F between 11.4-11.8 max.once you get to 12.0 and higher you will have big problems.i would also get rid of the brisk plugs and buy some autolite HTO's and gap them at 28-32.you will run into problems with the brisk plugs sooner than you think.i use to have a non cooled s-trim on my car and my A/F was 11.5 across the board.was tuned by moty johnson of jmschip.car had 3.80 pulley made 11.5psi at 6500rpm made 457rwhp-417rwtq.

Mudflap

The head/plug design was changed mid-2008. As far as I know, Brisk is the ONLY company making colder plugs in the new design right now, so I didn't really have a choice... I have heard mixed reviews on the Brisk plugs. Most people seem to prefer the Autolites, but I've seen negative and positive reviews of both. I do know that the plugs I have are literally a brand new design. I got a set out of the first batch they were able to produce, and they are still on backorder mostly. Perhaps they are better than the older style. Time will tell I guess...