Very upset...!

[ralphie]

Very upset with my dyno numbers. 398hp/401 torque. I would think headers, CAI, UD pulley, full bore TB, aluminum 1 piece driveshaft, and 3000 stall conv. would be better than that. I understand dyno's are for tuning, and the numbers shouldnt be taken seriously, BUT still. Was running a little lean, t/v cable wasnt disconnected, and the NOS spark plugs were still in there. Appointment made at JMB Perf. to cam this pig and dyno for N/A and the NOS...! Hope it helps..!

 

[VENOMOUS1 RACING]

Did you put Champions back in her for a new pull NA?

 

[ralphie]

yep...plugs are in there....thnx

 

[VENOMOUS1 RACING]

yep...plugs are in there....thnx

Get a new pull and see what she does bud

 

[earl lee]

What kind of dyno was this? Was this a mustang dyno? If so, they dyno everything low.

 

[VENOMOUS1 RACING]

What kind of dyno was this? Was this a mustang dyno? If so, they dyno everything low.

Nope I'd hoped the same

 

[seethrough]

Ralphie, where did you get it dynoed at? Did the tech that dynoed it say anything the low numbers? How low where your A/F numbers. Did the dyno tech run it in 3rd gear?

 

[ralphie]

Tuscola Il. Dyno-jet dyno 3 pulls. 1. a/f-13.4 2. 13.6 3. 13.7 As far as 3rd gear, not sure. All I know, when he kicked it down to make a pull, each time it downshifted.

 

[Psycho1122]

Yeah.... way too lean by almost a 1.0

A little fatter through the middle would bump TQ too.

Cheers!

 

[seethrough]

Those A/F numbers are rich not lean. Stoichiometric is 14.7:1 which means 14.7 parts air to 1 part fuel. A lower number means less air to fuel ratio - a.k.a. a fatter mixture. You get the best power being slightly rich although I think being a full point rich may be a little too much for a N/A vehicle. Also every dyno test that I have attended the tech either locks the vehicle in whatever gear gives them a 1:1 ratio (3rd gear in our trucks) and tries not to get it to kick down a gear. Not sure if that is for accurate readings or just to limit wear/damage on the dyno. On our trucks they can activate the tow/haul mode button to keep it in third gear.

 

[VENOMOUS1 RACING]

Yeah.... way too lean by almost a 1.0

A little fatter through the middle would bump TQ too.

Cheers!

He's lean through the middle and fattens out in higher rpms. Definitely not his huge loss of power. Thinking it needs a track run or two

 

[ralphie]

thats the button on the end of gear selector right? All I know is, by the time torque converter lockup, and high gear hit, the pull was about over.

 

[stealth78]

I know this has probably been asked a 100 times but what is an ideal a/f reading for an NA motor?

 

[stealth78]

This was my 3 pulls

 

[ralphie]

Good question because I thought the lower the number, the richer it was, higher meant leaner.

 

[stealth78]

Good question because I thought the lower the number, the richer it was, higher meant leaner.

Yes you are correct, higher is leaner. By looking at my Dyno pulls I'm guessing 12.5 is desirable but I could very well be wrong.

 

[ralphie]

mine

this is mine...looks lean to me...

 

[VENOMOUS1 RACING]

Weird but those graphs contradict themselves. Ones you showed me started rich then leaned out. Now there's another graph starting lean and fattening up towards end? A nice 12.8 is what I like to see

 

[ralphie]

so...under a load, mine ended up at 13.6 too lean...right? and a good target is 12.5-13.0 ?

 

[seethrough]

This is a good explanation:

When discussing engine tuning the 'Air/Fuel Ratio' (AFR) is one of the main topics. Proper AFR calibration is critical to performance and durability of the engine and it's components. The AFR defines the ratio of the amount of air consumed by the engine compared to the amount of fuel.

A 'Stoichiometric' AFR has the correct amount of air and fuel to produce a chemically complete combustion event. For gasoline engines, the stoichiometric, A/F ratio is 14.7:1, which means 14.7 parts of air to one part of fuel. The stoichiometric AFR depends on fuel type-- for alcohol it is 6.4:1 and 14.5:1 for diesel.

So what is meant by a rich or lean AFR? A lower AFR number contains less air than the 14.7:1 stoichiometric AFR, therefore it is a richer mixture. Conversely, a higher AFR number contains more air and therefore it is a leaner mixture.

For Example:
15.0:1 = Lean
14.7:1 = Stoichiometric
13.0:1 = Rich


Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.