c5z16z

LQ9 4.00 stroke 4.030 bore static comp 11.8:1 dynamic comp 8.2:1

what is the ideal safe air fuel ratio you want when building a N/A motor ?

and were would you want your dynamic comp on a N/A motor safely all this on 93 pump ?

thanks fellas

Sales@Tick

iTrader: (3)

Most N/A motors make peak torque at or around 12.5-12.7 AFR and peak horsepower at 12.9-13.3 AFR.

AFR isn't something you build for though, it is something you tune for

I normally shoot for 8.5:1-8.8:1 dynamic.

c5z16z

thanks martin,

and i understand you , yes you tune for afr just wanted to know were it should be at

also i have been told anything over 8.5:1 dynamic is pushing it on 93 pump gas ? was that incorrect info i received

Bill00Formula

iTrader: (4)

I didn't think you ever wanted to go over 12.7-12.8 AFR in a street car if you want the engine to last a long time.

c5z16z

thanks bill, appreciate the info trying to learn a thing or 2, for a street driven car,,

Sales@Tick

iTrader: (3)

Richer is not safer and this is incorrect.

Many many many people have run including myself N/A motors at 13.0-13.3 AFR with no ill results.

I normally try and shoot for 12.4-13.0 on nitrous applications and 11.4-12.0 on boosted applications depending on fuel used. N/A I and our tuner will get them at 12.5-12.7 right before peak torque and progressively lean them out to 13.0-13.2 as they approach and reach peak horsepower.

SS10Tech

Most modern vehicles today sold at the dealership are sitting around 14.7:1 AFR, with 16:1 as the max i have read. I have seen some guys tune for 14:1 for gas mileage in low CR setups running colder plugs in turbo builds strictly concerned with mileage in mind and not HP or torque.

Most builds NA that make the best balance of HP and torque are at 13:1. But it really depends on the application and purpose of the motor as Martin already mentioned.

Bill00Formula

iTrader: (4)

I'm definately not an expert but I am very surprised to hear someone say that based on what I have heard in the past.

SMOKINV8

iTrader: (6)

So you're saying that running a car at 12.8 afr isn't any less likely to detonate than the same car running at 13.0 with the same timing in the same conditions?

To the OP, it depends on your heads usually. Best bet is to get on a dyno and find the answers for yourself, but 12.5-12.8 is a good midrange to shoot for depending on what you've got.

willyfastz

I totally agree, only thing I've seen that's changed this a little is the blended ethanol gas. It has to be a little richer than straight gas.