Safe Air/ Fuel ratio ?

[DEADEYE]

Can somebody tell me whether or not this is a safe A/F ratio for a street tune? A supra buddy of mine thinks it's too lean for the street on a W/M car. I honestly wouldn't know any better. The car is a Roe 10# on W/M.

 

[RX VIPER]

I'll let a tuner make that call but for you to drop well under 12.0 at 3500 rpm's seems pretty lean. Your hp also drops at that point so it could be costing you power.

 

[Russ M]

Deadeye,

Ideal on a street car with low boost is 11.5-11.8 to 1 for me on pump gas. If I had race fuel then it would probably be 12-12.5:1. So based on that I would say you are a bit on the lean side, and I bet the amount of **** you are adding is insignificant.

RX Viper,
The lower the number the richer you are not leaner and his hp is going up not down, you are looking at the torque...

 

[BOTTLEFED]

send your dyno sheet and a log off your VEC to Sean and see what he thinks

it looks fine to me
Sean recommended 12.2 AFRs for w/m tuning (on cast pistons even)
your Supra buddy is used to tuning for much higher boost (typically 20+psi) and probably doesn't understand tuning with w/m

BTW, was the WB in your tailpipe or swapped into your stock O2 location? this can cause very different readings when monitoring AFRs
and who tuned it to begin with? you might want to ask them about the tune first

 

[DEADEYE]

The car was tuned by Sean himself. The WB was probably in the tailpipe but that's just a guess. It was tuned a long time ago so I doubt he'd remember the small details. Thanks for the replies guys.

 

[plumcrazy]

if it was his dyno, he used to have a tailpipe sniffer.

 

[GTSnake]

It looks fine to me. Remember the lower the number the richer the AF. Before I got boosted I was around 12 - 12.5 AF and it was making good power without detonation. After boost I dropped to around 11 - 11.5. With your W/M you should be fine. I would even say that's a little conservative. You could probably go a little leaner when the W/M kicks in. But if you have cast pistons I would say conservative is the way to go.

 

[Joseph Dell]

Insufficient information for anybody to comment. The variables which have not been considered are:
- What octane fuel are you running?
- What % of methanol are you injecting?
- How much methanol are you injecting, and what size jets are in use?
- Is the A/F rating taken pre- or post- cats?
- while not the end-all-be-all, what were the conditions at the time of the run?
- What were your air intake temps?

I'll make some guesses here: you are running pump gas + an unknown blend of water-**** with extremely hot intake temps and no cats. If that is spot on, i'd add some fuel. the 10lb pulley's air temp when output is extremely hot and while in a closed room your performance was fine, when you have been driving even at low speeds and you then get on it, the hot air temps are going to rob you of power and you could use the extra fuel to act as cooling. also, your net octane rating w/ an unknown amount of W/M is not high enough to target a 12.0 A/F. 11.5 tapering to 11.0 from 4500-6k is what you want in the dyno room b/c on the street, you'll be leaner.

my .02... good luck!

 

[EllowViper]

Spot on JD...Plus I'm having a hell of a time with my exhaust temps now that I'm into the 10-12PSI range. Keep cooking my W/B sensor even with a heat shield (in collector) so getting a good A/F reading during tuning sessions is just hell when the sensor shorts out. Your comment about the blower heat with the 10 lb is an issue too. I can't even put my hand on the blower its that hot. So tuning for a steady-state AFR changes based on actual IAT experienced "post blower" by the motor. Unmeasurable for the most part unless you relocate the factory sensor in the manifold. Due to the maniforld/blower heat sink issue, I am running (10) .063 mml injectors located in the intake runners @ 200 PSI and an still trying to dial-in that system. I did read a great article that did support running W/M before the blower since it helps to seal the rotor lobs resulting in more boost/less leakage plus cools the blower as well. I may locate one 325 mml injector back in the intake tube just to do this. But first I have to get my WB sensor cooled a bit. Good stuff.

 

[EllowViper]

Deadeye,
Can you"E" mail me your tune? I'd like to compare notes.
[email protected]

 

[BOTTLEFED]

good point JD
I just assumed he knows little bit about what he is doing - but you never know
also, I was assuming it is a Roe w/m kit so it would have 325cc nozzles

Sean usually tune pretty conservative so maybe these conditions were not the most desirable, or the AFR was not well calibrated
as I stated, send a log to Sean and he can tell you if the tune is ok or not

 

[DEADEYE]

I run 93 octane and I use -20 windshield washer fluid for the **** mixture. That's about all I know for sure. The dyno run was taken in November in Florida if that helps out any lol. I don't have any tune logs to e-mail. I guess I need a laptop for that, I'll borrow a friends and get on it. Thanks again guys.

 

[99 R/T 10]

I use 93 octane and run the -20 windshield too(approx 35% ****), BUT I also add a bottle of HEET(yellow). It is 99.9% **** and that brings the total to about 50%. On 8 lbs, I run at about 12.0-12.2 A/F. Safe for the most part, important to always have good gas regardless. I think if you are down to 91 Octane due to location, it would be best to run richer just to be safe.

 

[Qualitywires.com]

I use 93 octane and run the -20 windshield too(approx 35% ****), BUT I also add a bottle of HEET(yellow). It is 99.9% **** and that brings the total to about 50%. On 8 lbs, I run at about 12.0-12.2 A/F. Safe for the most part, important to always have good gas regardless. I think if you are down to 91 Octane due to location, it would be best to run richer just to be safe.

You're using Heet? Are you rich or something? LOL! Go to a go cart place and pick up a gallon of pure **** for about $5 bucks. Mix your own with distilled water. By the way **** has a self life and try not to let light into it since that will decrease the life of it.

 

[Red Snake]

Mine runs 11.8-12.0 with 10 pounds of boost. I also run 50/50 mix of methanol and distilled water and 93 octane.

 

[99 R/T 10]

You're using Heet? Are you rich or something? LOL! Go to a go cart place and pick up a gallon of pure **** for about $5 bucks. Mix your own with distilled water. By the way **** has a self life and try not to let light into it since that will decrease the life of it.

Eh, total cost to fill-up is $2.50($1.40 for the washer stuff and $.99 for the HEET). I would rather have the mix available an simple. I can go to any auto parts store and get a near 50/50 mix and not worry about storing the ****. And since my container is in the trunk, no worries about the sun................ unless it's on my balding head.............................