Hello guys. Ive seen alot of different target AFR for WOT in these DI cars. RPM has a video where Fran is saying how they target 13.0 on all N/A DI cars they tune. But when I watch his WB i see 12.5-8
What is the reason for this? I know DI cars can run leaner. When I tune boosted euro stuff with DI i target .85-.80 lambda
What are your thoughts on this?
It really just depends on the application. I lean out the cars a little more than the trucks. On our dyno, I've tested several LT1's anywhere from 12.0 to 13.6 AFR. Typically, a good stock engine or FBO engine will make best peak power around 13.3 AFR on ours. However, most of them are within 4-5 hp if you richen them to 13.0 AFR.
Sounds good. Ive been running 12.7 on them and just not getting enough power
Give the engine what it likes!
Lean is mean
I prefer the slightly richer side on pump gas because I don't care about that last 10 horsepower I might be losing out on. I'm talking mid 12's here.
E85 I run leaner because I know I can and that's closer to 13.0.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
That's a very accurate statement. I was tuning an L8T on the dyno a few months ago, with a Holley Terminator X Max ECU. I started at 13.0:1 AFR. The power was pretty sad...around 340rwhp. I leaned it to 13.2:1, and it lost another 8 hp.Originally Posted by cadillactech
So, I richened it to 12.8...it picked up. Next went to 12.6, and it picked up again. Ended up making 379 rwhp at an extremely rich 12.2:1.
Hopefully Holley will give us the ability to change EOI soon. I'm sure we can pick up power and end up with a much more appropriate AFR.
I have found that once you know what an family of engines likes, you can usually set and forget it but I still will always go half a point rich or lean to see if the engine wants something different. It has surprised me a few times! Same concept goes for timing too. You never really know until you start testing a little on the dyno.
On pump fuel ?
Never gained 1 hp over 12.9 on these engines unless it's on E .
That's correct. On 93 octane pump gas...typically E10.
Are you saying 12.9:1 is best on a stock LT1 or modified...or both?
We have two different widebands. I typically just use the one on our dynojet. Occasionally, I'll use my AEM as well.
Interestingly, there's approx 0.3 difference in the dynoject wideband and the AEM.
I've also tested several Holley systems with Bosch or NTK sensors. Very seldom do they read the exact same number...but are typically within 0.1-0.2.
Last edited by kevin87turbot; 07-08-2021 at 08:21 PM.
A good BALLPARK target for the LT1/LT4 platform. But it really depends on the mods and if the engine likes it a little leaner or richer. I tend to target the per below and then make sure the fuel trims are not taking any fuel away. I prefer to have the fuel trims slightly positive(1-3%) in WOT area of the MAF so that Lamda goes .01-.02 richer than target. Reason being is perhaps weather could cause the car to run leaner for a little while until it adjusts the trims or a Wideband could be slightly off. I err on the side of rich because the power you gain being lean is negligible vs having a slightly richer mixture and being safer. (even Fran at RPM demonstrates this in one of his videos)
LT1 =.88
LT4= .84
On LT4's with full bolt on's, pulleys and ported blowers with Methanol, I prefer to target .82-.83. They seem to like it a little richer. Stock pulley cars I still target .84. On my personal LT4 I run it around .84-.85 Lambda with no issues but I wouldn't send a final tune to a customers car that lean only because they aren't monitoring their fueling like I would and there needs to be room for error/weather changes. A lot of the stuff I tune is in Texas and Florida so other may not have the same results. There are some VERY smart and experienced tuners on here that have slightly different points of view and experiences than I have but that doesn't mean either of us are wrong. It just means the variables(weather, cars, mods, dyno, wideband sensor, comfort level) are all different. So I only give my advice as a ballpark and recommend you use a dyno or the track to test your results.
PS: Flex fuel, E55 and above can tolerate leaner mixtures without compromising safety. But, you need to measure on the dyno if being leaner vs having the additional oxygen molecules from the Ethanol being slightly richer, makes any more power.
Last edited by TriPinTaZ; 07-09-2021 at 08:40 AM.
No , im saying on a NA stuff usually 12.6-12.9 are the sweet spot on LT's , people still thinks the DI should run leaner than PI but for me dyno sessions proved that wrong , leaner won't help gain any power unless it has a heavy E content .
LT1
YSi-V7, ported heads,headers,large cam, 3.8 upper if I remember correct and stock dia. lower, .85 is happiest for me.
I always tune VVE....
2016 C7 M7 Z51
Callies ultra billet crank
Callies ultra billet rods
Diamond pistons
Jhonson high speed lifters
Ported and polished headwork
Custom cam
YSi-V7
Yeah I have always seen the same. I have seen it 3 times this week already. I think it's the internet telling me that they should like to be leaner that makes me test them all... I had 2017 Camaro today with a TSP stg 3 non-VVT "VVT cam" (whatever that means) and my base file returned 12.4-12.5 at WOT and nothing I could do following would do better on the mixture end. I made a pull at 13.0 and it was down 6-8 ft lbs everywhere.... 12.8 was down 3-4. So back to about 12.5:1 it was. At 12.2 it lost a ft lb or 2. Heavy E and I can run it 13-13.1 and see it happy.
Exactly .
Keep the good work man .
I notice the exact same Steve. I think a lot of it depends on what wideband people are using too. In general it seems like the afr500 with a ntk reports significantly richer than say an aem with a bosch sensor.
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Absolutely...
I have watched 2 NTK-sensor'd (each bank) streams with a Bosch sensor (any of those commercial controllers, including the Dynojet unit) behind them hundreds of times. The Bosch units, regardless of controller and it's cal, will consistently return 0.4-05.pt leaner then the NTK / AFXs. In the past, this probably helped lots of tuners that tended to just target fixed mixtures, as it left engines slightly richer than they believed. There are 15 years + of N/A LS1 dyno graphs that show (on the graph) 13.0:1 delivering best torque (built in Bosch sensor), but the same HPTuner's logs on my end will normally show around 12.6:1.
I have yet to experience such a large disparity between the afr500v2 and an aem, and I was putting both on cars for a while just to see what the difference was. At most I saw .1 lambda on 3 different vehicles, even switching them around between the tailpipe and the rear o2 ports (non catted cars). It may make a difference that I air cal my aems every time I use them, and never use the resistor cal I suppose.
I see it with most any Bosch sensor; regardless of controller. I may only notice more often than others as I tune by the AFX (front bung(s)) and use the Bosch from the dyno in the tailpipe or a rear bung.... mostly just because it's there.
I have been meaning to do a comparison between an AFR500 with a NTK and a controller with a built in NTK wideband like a holley. It just seems that I never get a car with two bungs on the same bank to test it on.
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