I did do a search, but if someone can point me to an existing thread, I will delete this one...

Air fuels are a big topic and I just got a vortech installed and at 8psi (stock boost) I am running from roughly 11.7 to 12.0 not to exceed 12.0 on a G35 RevUp motor....APS Tall, HF Cats, Stillen Y...stock for EVERYTHING ELSE!

Everyone has thier two cents on 11.5 or 11.0 being the max Air Fuel ratio...

I agree in cases of 11psi or more, but I do not agree with this at 8psi. (my unprofessional opinion) lol

Does anyone have or can explain basic psi level vs air fuels. We all realize that its a complicated formula of timing, injectors, etc... but generalizing...

or

is there a magic number that works through the boost range?

8psi should be around ?
9
10
11
12
13
14
and so on?

Thanks, just trying to get a solid format for us to fight with tuners (those who can not or dont tune thier own cars).

 

Good thread.. I don't think there is much difference let say 8psi vs 11psi in term of A/F. Tuner just tend to give rich A/F at around Peak TQ just because that is were you have a great chance of knock. Also some tuner richen up the higher RPM just for safety or just in case the driver do mishift... Some tuner also run richer A/F in warm weather state just for some added cooling. Some tuner run leaner A/F but low on the timing side but some tune with more timing but fatter A/F. It is really more of how your car responde I guess.

My old tune was around low 11's at peak boost but with my Meth I have been running mid 11's lately. My goals is to feel comfortable and see how my car react since I feel my car really perform much better on high 11's. There are really to many variable to consider like Timing, Octane..etc so you can't really have one set of rule in term of A/F.

 

I'm running the 3.125 with a non revup engine, I have a air/fuel ratio of 9.8 to 10.5...

with motordyne spacer, Berk MHFC and skunk 2 cat back... and some people here are telling me to run bigger inj with the 2.87 pulley... anyway...

Do not forget... your stock ECU still detecting knock...

yes you have the ssbox that is retarding the timing... of your ECU.... but your ECU still in fonction and if it detect any knock, it will retard the timing too...

 

/\ yo, 9.8-10.5 is Rich as hell.... ECU do detect knock but when they do, they pull a lot of timing.

 

Well he told me that the timing was really conservative so the 11.7-12.0 range would work best with my Vortech RevUp running UniChip.

I listened to the car extremely carefully and there is no knock (to my human ears anyways).

Just trying to get a sense of:

AIR FUEL VS PSI because it seems that running 15psi with 12.0 air fuels would spell disaster!

 

You can run leaner A/F's with less timing. You dont want lots of timing and be on the verge of lean for pump gas which is high 11's A/F, its asking for knock/detonation.

The only way to know if your A/F at 12:1 is "safe" is to have somebody look at the tune. Two extremes here but:

1. Stock Greddy emanage on Greddy TT (no pulled timing on base map) @ 12:1 = boom

2. Tuned car by XXXXX shop, with conservative timing, no knock can be safe @ 12:1.

Every VQ is different some can run great at high 11's others need to be richer. There is no definitive answer only a general range of whats acceptable.

My first built set-up liked 11-11.5:1

This setup likes 11.5-12:1

edit-there is also no set timing value per boost level, every VQ is different. Both of my motors ran very different timing values near redline.

edit #2-dont rely on your stock ECU to pull timing because of knock LOL!! If it did nobody would blow up engines at conservative power levels.

edit #3-sorry I keep thinking of $hit. With better EMS's you can generally see slightly more agressive timing because the tuner knows what he dials in, and it works. With say a UTEC you can set timing for 15 degrees at reldine but who really knows what its doing? Thats why generally when somebody switches from a UTEC or Unichip to FCON they gain power at the same boost level, better fine tuning.

Good luck!

 

the best A/F R is 11.8 and with this range on a Z or a G u will get the best power. (im talking about turbo)

for a supercharge its not the same

ull be just fine with 12 .

but im sure all tuners here will Disagree

if u need any help to tune ur car ill be glad to help

 

thanks all, Alberto, and others..being a newb to boost i just like to tripple double, quadrople, check twice...lol

I feel that the car running 8psi, pulled timing, and 93+ octane will be great for all my daily needs.

there just seems to be a wide range of opinions with nothing standard. Now I am starting to see why a Greddy TT will put down 400 at a shop then the same kit on a different car will put down 10-15 wheel more with the exact same set up from exhaust to injectors...

thanks again

 

You guys have higher octane in Kuwait right? California and other state only have 91 octane. For Cali guys to run 11.8 they really need to run low timing. But I do agree the close you can get to 12 without knocking will probably best but then again, most tuner will always be in the safe side since they don't know how their customer will drive their car.

 

My opinion on a stock block you shouldnt see over 11.5:1 A/F's from TQ peak to redline. As your getting into boost seeing leaner is fine. A car running pump with a tune at 12:1 with a bad tank of gas (Ive had 3 in my FI lifetime) and you will detonate. Its happened to me 2X while logging my UTEC back in the day.

 

+1 Happened to me 1 time. I had bad gas that it took me 2 fillup to empty it out. This is why I don't fillup at any Exon/Mobile station anymore

 

I always use Vpower...seems pretty quality

 

Yeah, my tuner told me only Sunoco or Shell 93 oct

 

2X Ive had bad gas from Exxon-JUNK gas!

Sunoco or V-power FTW

 

with a Vortech, you have a progressive boost, so you will hit your max boost only at the red line...

you can safely run a vortech with a air/fuel ration of 12.5... it is not like a turbo setup that will give you a max torque à 3500 rpm...

 

Getting into boost you can run leaner, but you cant be serious that you would run 12.5 A/F's throughout the powerband.

BTW-max TQ on VQ's for 95% of people is at 4800rpm's

 

absolutely... 11.5 to 12 is very safe, 12 to 12.5 is safe... 13 and over...not sure...

I said, you will hit max boost at red line... not trq...

a Vortech is much less stress on the engine than a turbo...

 

Not mine.

 

I personally wouldn't run 12.5. Although, I'm super conservative and am running no higher than 11.1 to red line.

 

BTW-max TQ on VQ's for 95% of people is at 4800rpm's
5700 for me @11.5A/F

After seeing what happen to Nexx, I wouldn't want to run 12 on my A/F.