Shinobi'sZ

Given a choice, and you were tuning or having your car tuned for a Centrifugal S/C application on a Dynojet. What would your target AFR be. Stock or Forged Application is fine but please indicate for which. No Alky, assume 91-93 octane. Turbo application is fine too just indicate Turbo.

DeltaT

iTrader: (5)

It depends if your motor is knock-limited or not. Some blown motors require as rich an AFR as 10.8 to fight knock by combustion cooling with the extra fuel.

If the engine is not knock-limited, at WOT you would find mean best torque around 12.4:1, but I pad mine to have an insurance buffer so I'm looking for 12:0 - 12:2 at peak torque and say 12.2-12.4 at peak power. But I'm only running my built 383 at a maxed out blower (V-2 SQ S-trim) boost of 7.7# after the throttle and FMIC. When I upgrade to the V-2 T-trim I will start again with a target of 11.6 at WOT and tune towards 11.8-12.0 at 10-11# of boost at peak torque and 12.2 - 12.4 at peak power. That's assuming that at the increased boost level I don't experience a lot of knock.

I highly recommend Jeff Hartman's book "How to Tune and Modify Engine Management Systems". It has helped me a lot. That and having my own wideband O2 so I can drive and datalog, then tweak.

Jim

My Site: http://home.mindspring.com/~jim_fisk/id1.html

The Juggernaut

iTrader: (7)

You should ask 01-Z, I hear he is fast.

Shinobi'sZ

lol...nah I don't want a skewed biased opinion. I am just looking for what others have done with the FI setups and what afr they have targetted for their tune.

Nice try though. See the guy who posted above you, he is giving a good answer.

The Juggernaut

iTrader: (7)

Oh, you're looking for dyno queen answers, not people who actually race.

Sorry, My bad.

Shinobi'sZ

Nope just what AFR most people target when they are tuning their setups. Nothing more and nothing less.

Doesn't have to be dyno numbers either.

If they are using the street to tune with a wideband, they can report that AFR as well.

If I don't get the info here I will just keep my eye out for when people post up their results. They usually state what the AFR is.

Pro Stock John

iTrader: (34)

What power level?

Shinobi'sZ

How about for a stock setup? No alky. Supercharged.

I know with my forged setup at over 870bhp my afr was at 11.9-12.0 from 6000-6500rpms.

I am mainly interested in what the general or average afr is for what would be considered a good tune off of a dynojet for a Centrifugal SC, on a stock ls1.

My thoughts are 11.5-11.9.

chriswtx

iTrader: (5)

street to tune with a wideband here and HP tuners, stock bottom end. I'm at 10.5-11.0:1 AFR and 14-16* timing. Running rich to save the stock pistons until I can build a forged bottom...

Shinobi'sZ

That sounds right to me, and is what I used to see a lot on this forum a couple years back when we all started getting into FI for the LSx. After quite a few motors went pop in the early days, people quit tuning the stockers and some of the forged motors like they would for a NA tune. Its been a long time since I was NA but I think we used to go for about 12.9-13.1 for NA...on the dyno!

Thanks for your input.

DeltaT

iTrader: (5)

There seem to be quite a few tuners that leave the WOT area rich because they have fewer hassles that way, and most people wouldn't notice the difference. Same with timing - leave it backed off like 5-8 degrees for a very 'safe' tune. I guess if I were in the business I would do it too, with all the idiotic stuff people do to/with their cars.

Jim

Nickn20

I always shoot for an 11.5 AFR, if you need to go richer than that to combat knock, then lower your timing for crying out loud! lol the gas is just unstable.

kp

iTrader: (34)

On the street with 93 I keep it at 11-11.5:1
On the track I run 12-12.7:1 with 104 unleaded, makes the most power but you have to keep an eye on things

Shinobi'sZ

kp and others..I appreciate your input. I was having a discussion on the another forum about what I would feel most comfortable with running a S/C on a stock LS1 with pump gas. Pump gas being 91-93 octane...not Sunoco or Trick.

The question was about tuning. The application was a S/C application on a stock LS1. Based on my experience and others I felt a good target AFR was from 11.5-11.9. With 12.0 being the max I would consider, but not really comfortable with. So I thought I would ask over here to see if opinions or thoughts had changed on the matter.


Thanks