What's the most beneficial A/F ratio?
 

I dyno tuned today, got 204.56 WHP 210.03 WTQ, '97 Auto with VQ35, numbers are uncorrected, correected they are 199.xx WHP, 205.xx WTQ. My A/F ratio seems to be between 12.2-12.5 a hair below 13, I got the files e mailed to me but need the software to upload the files. I'm asking about the A/F R. because after driving 150 miles or so I got a code, 0210, left bank fuel inj system: lean.

I expected more power than that. AF should be closer to 13-13.5. You should make more power with that ratio.

You're right on his as.s Kevlo911....

But he has more volume among other things... :rotz:

Believe the optimum A/F ratio for N/A cars is 13.5:1, while the optimum for boosted cars is around 12:1.

Run files have been sent, will I be safe with my A/F ratio between 12.0-12.5?

Overly so. 12.0-12.5 is too rich (not unsafe, but pointlessly rich).

Timing is where the power is at really. AFR will affect your power a little bit, but you probably wont gain more than 5hp or so going from 12.5-13.5.

Is this a good example of what a VQ35 will put down w/o VTC?

allen

No, that is a good example of what a VQ35 puts down with sh*tty timing. VTC's are worthless above 4000 rpms.

With that said, isn't that pretty much what a stock 2k2 auto dynos, no? Do you have any mods?

Can we see the runfile? This would be the first time we actually see the dyno curve of a 4.5 gen *drumroll*

If he tunes to 13.5, he will be pulling fuel which indirectly adds timing ;)

:Orly: Speak for yourself...:grinno: :wall:

He has 00VI.

Check this thread in the Z forums. Highest N/A HP has been obtained with a 12.0-12.3 a/f from 3k upward.

http://www.my350z.com/forum/showthre...=165068&page=2

Last year I ran most of the season with a 12.5 N/A.

Holy balls 313whp even if that's inflated it is utterly amazing. That guy may actually be putting down 290whp or so with STOCK CAMS. Can you imagine that in your 2600 lb GXE, Jim? Hello 110 mph traps.

So 12.5 it is then.

What kind of dyno is that? It's not a DJ...

Not sure I'll talk to Tilley.

No no, yours is a DJ, Iw as referring to the Z33 dyno provided in the link...

I got yours and thanks.

Please post it.

Read the whole thread, thats what its all about, good reading.

Wow, talk about a lot of cynical responses in that Z thread... I guess we can only wait and see what the new dyno will show.

yup.. sure is.

But definitivley, many opinions can be made etc, but unless it was done on a DJ, then that would be the deciding factor.

Also, the shape of the curve is important, and I'm surprised he's still at 6500 rev limit still.

HarrisH's dynos


http://i4.photobucket.com/albums/y124/nmexmax/hsaf.jpg
http://i4.photobucket.com/albums/y124/nmexmax/hp.jpg
http://i4.photobucket.com/albums/y124/nmexmax/tq.jpg

I read that thread in the Z forums a few days ago.. it was impressive, until I realized it wasn't a dynojet. Wonder what it would be on a dj.

As far as A/F goes, I honestly don't think it makes much difference from above 12.5 up to 13.5. Any time I've been tuning on a dynojet, I saw little change in power past higher than 12.8 so I set mine 13.0 to 13.2 on average as a compromise between fuel economy and knock resistance. Mind you, that's on a VQ30 not a VQ35 but others who have tuned a VQ35 seem to think 13.0 to 13.5 is best (SR20DEN for example, on a Mustang dyno which is better than a dynojet for tuning).

I don't think my last run was included I will have to scan it. That was 210.xx WTQ, 204.xx WHP UNCORRECTED. A/F Ratio was between 12.0-13.0.

I see a problem. The AF needs to be a FLAT line, you will make more power that way.


Hmmm, I need headers and a Pathy TB and I might start catching up to you :wall:

The higher the number for the AFR the leaner?

Correct. ..

I only got 6 files and one had some corrupt data.... :gotme:

Shudup :squint:

Looking at that dyno, it seems like timing is the one to point the finger at. And worst is, it's impossible to predict how much of a different it would/will make.





Ooooh this is killing me. We just had another giant snowstorm. Winter shows no sign of letting up. Three months down, three to go. :sadwavey:

What about the MAF...Cheaper and easy to upgrade on your own, and well, it might accomodate the PF TB a wee bit better.

So the highest power it made was 199.xx and 204.xx CORRECTED A/F Ratio was between 12 and 13.

Anyone care to comment on my 0210 code which is for running lean?

Ahh, I see. I thought the VTC's added power in the upper RPM's (like VTEC). I take it the stock cams are basically high HP/RPM cams and the VTC's just change the timing to bump the low RPM power up for better drivability then, right?

allen

I don't see your A/F ever going higher than 12.6 or so. Maybe bump it up into the low 13's and see how the curves change. Keep in mind your variations in power are likely timing related as well, since tuning with an SAFC/VAFC (don't remember what you have) will indirectly affect timing.

My comments on not seeing a difference in power due to A/F fluctuations between med-high 12's up to 13.5 are based on changing fuel only, not timing, which I can control independently with the EU. You may get slightly different results since you are changing timing when you change fuel via MAF conditioning.

Exactly. But you don't need the VTC's in a 4th gen or a 240 with the 3.5, so sleep well. :laugh:

Thanks, that what I was thinking of!

allen

Harris your car is still slow. We should put it up against my black car.....

FU&( Yea man that **** is insanely fast, you guys gotta wait and see what this sh8 puts down, spinning after 4K in 3rd equals :drool1:

im not sure if anybody noticed this, but his best run was on the leanest curve, shouldnt that seem to say the leaner might make more power, always worth a try at least i would think.

Are all the injectors good? Are they all connected? Any misfire? That might be why it is throwing a lean code.

Are ALL the ports lined up for the 00vi? If not, you might have an air leak causing it to run lean and losing alot of power.

All injectors are good as far as I know, no misfire codes, 00VI has been on for months, first time I'm getting this code, hopefully it's just a glitch.

Oh I see.

Re-dyno tune the car and make the AF FLAT at 13.0 from 3000+(or 3500+)

All these VQ35 4th gen swaps and no one has done a decent tune... :banghead:

Only if I had the cash to blow on this car. :slant: