Everyone, we could talk about variables all night regarding engine particulars (correct timing, mods, CR). But a simple question is this:

What is a dangerous AFR to run at WOT N/A?

This is to help understand a question we have in this post: http://web.camaross.com/forums/showt...hreadid=143169

Thanks all!

Ben

 

I read some other posts indicating where some have run, by mistake, lean on their cars. However, I do not know if it damaged them or not.

The real question should be: is it safe to run our cars at stoich. (14.7:1 AFR) for short periods of time at full RPM and WOT...say 4-5 sec. at a time.

Thanks all.

 

While other cars my run slightly different, a good starting point for NA cars is 12.9:1 at peak torque, and slightly leaned to 13.1:1 at peak HP. Again, that's not a cure all, but a good starting point.

 

My car made best power at 13.4

 

Thanks for the replys and I will use that info when I go back on the dyno. However:

I need to know if it is dangerous to run our cars at 14.7:1 AFR for any length of time at WOT? Will this damage pistons, heads, valves? This is an issue based upon the post I have going in the computer section. Some are wary of doing this as they feel it may damage the engine running at 14.7 AFR in WOT.

Ben

 

14.7:1 is too lean at WOT. You'll eat something sooner, rather than later.

 

Why would you want to??? You're not gonna make power, and like 4drLT4 said, you're gonna munch parts.

 

Read the linked thread. The theory: In order to calculate A:F on paper (with the formula we have) you must dial in the BLMs at 128/14.7:1.

EDIT: The above is theoretical. Don't want to come off sounding like I'm passing off facts.

The question: Is running 14.7:1 for a 3-4 3000-6500rpms runs (one gear only) - How dangerous?

Ryan

 

Thanks Ryan for that clarification.

Ultimately, will the LT1 engine be hurt if a car is run at Stoich. AFR for upwards of 5-6 runs of 5-6 seconds each?

This is for testing then PE would be enabled again.

 

To my understanding there is no magical safe max AFR to run at WOT. My car ran from 15:1 tapering to a 13.2:1 with no detonation. It might pick up some power if I were to richen it up, especially above 4000 rpms. Once I get some good tires, I can go to the track and play with the fueling to see what is best. Stoich is simply what is the most optimal for emmissions. It has nothing to do with performance. You could have a car that performs best at 15:1 and doesn't detonate until 16:1. Its all in the comprehensive design of the engine, mostly the heads.

 

Guys, all replies here are appreciated...but I just want to clarify something.
What 95Blackhawk is looking for is if anyone knows how dangerous it would be to run your car at stoich (14.7:1) for 5-6 seconds at a time.
We are trying to find a way that may allow for an easier setup of the pe tables before final tuning is done on a wideband. That way you spend less time on the dyno, saving you money.

 

That is too lean to run on a regular basis for 4 or 5 runs though at 4 or 5 seconds each I don't think it'll break any parts...I've seen 2 cars (both LT1's one in a 3rd gen though) run more than 14.7:1 on a dyno while it was being tuned. One car pulled three runs above 14.7:1 the other had one run...and neither car had problems...the one car was terribly lean in the beginning like 15.8:1 or something terrible...then 15.0 then 14.8 etc...I think one time you'll be ok...Ideally for a tuned car you wanna be around 13.0:1 to 13.3:1 (at least thats what I gather from my readings)

 

Here is a link to my a/f when my car was stock. Granted it gets a little rich (relative) in the midrange, but it is real lean on the low and top end. No tuning, bone-stock car. Never had a problem with it running. Car went 13.8 @ 101 on a slipping clutch. You shouldn't have a problem. I wouldn't spray it though!

http://users.compuzone.net/dsmturboawd/airfuelstock.jpg

 

All I can say is Deeyam! Really hope you got that lean condition tuned out!

Thanks all for the input. I also saw a few other at Dyno Day pull over 14:1 AFR. I myself was close to 14:1 before I tuned, but I was knocking like hell.

 

Big question...

Were you seeing any knock retard?

Either way, that says something right there!

Ryan