Dyno a/f reading.

[jayro]

I have a couple of questions regarding a/f readings at a dyno. I am trying to make since of the data I received. Once I get my graph scanned ect I will post it. The dyno used a probe that they stick up the tailpipe about 2 ft. They put it in the right side exhaust since I had a hole in my left side muffler.....they said the hole would throw the reading off. The questions I have are this:
1. What effect would going cat less have on my reading?
2. How accurate is this way of reading? I thought I remembered reading they they will usually read .1 to.2 leaner.

My numbers are 233whp and 210 ftlbs. This is a bos 3.2 plus triflows.

Here are the pics

This is my 80mm maf (blue) vs my PMASS 75mm maf (red, which uses the stock curve). Same basic tune, just accounting for the different MAF

This is my new 3.2 vs my old 3.0. Same mods except a Shosource catless y instead of a magnaflow, a 69mm TB and a ShoSource lightened steel flywheel.

The A/f dotted line is at 13.0

 

[SHOtime2511]

1. Catless should not effect anything.
2. Its not as accurate as a wideband mounted in your exhaust but still good.

Nice numbers BTW!

 

[jayro]

1. Catless should not effect anything.
2. Its not as accurate as a wideband mounted in your exhaust but still good.

Nice numbers BTW!

Thanks. With a tune I think there is a few more ponies there. The A/F was in the 10 and 11 range pretty much the whole run and pegged below 10 from 6k on. This killed me up top, which was illustrated by my peak HP being 500 to 700 rpms earlier in the band. I am working with ShoSource on tuning my LPM. Id like to see 240 whp, but Im happy with what I got. I picked up 30ftlbs and 24hp at the wheels over my old 3.0.

 

[vortex2450]

I can definitely see quite a few horses hiding in that top end there. I've noticed that the SHO engines don't mind running a tad leaner than the "ideal" 13.8 or whatever. The 80mm MAF is doing a good job compensating, just needs an overall bump and some fuel up top .

After seeing your graphs I'm suddenly motivated to start saving for tri-flows....

The torque curve looks really good up until the A/f really starts dropping, seems like once your dialed in with a refreshed LPM you'll be experiencing endless powah!! Excellent numbers. I likey!

-Josh

 

[jayro]

I can definitely see quite a few horses hiding in that top end there. I've noticed that the SHO engines don't mind running a tad leaner than the "ideal" 13.8 or whatever. The 80mm MAF is doing a good job compensating, just needs an overall bump and some fuel up top .

-Josh

Thanks. I may have misread your post. It is actually running REALLY rich. It needs to be leaned out up top. I'm thinking of trying to get it in the 13.1 range across the rpm band. Higher the a/f number the leaner it is. Hope u get ur alignment taken care of.

And yes I am diggin the triflows.

 

[vortex2450]

Thanks. I may have misread your post. It is actually running REALLY rich. It needs to be leaned out up top. I'm thinking of trying to get it in the 13.1 range across the rpm band. Higher the a/f number the leaner it is. Hope u get ur alignment taken care of.

And yes I am diggin the triflows.

I'm sorry your right, I was reading those graphs too fast and I mixed up lean/rich as your said, worked a long week, haha.

At least it's better to run rich vs. running lean. The problem which being so rich up top beyond the loss of power is that if you suddenly decelerate ( as in slamm on brakes, miss a shift/ let clutch out) you run the risk of the cylinders flooding and the engine dieing, I had it happen a couple times with my 3.0 towards to end of it's life...

13.1 is a safe number, I would run a tad leaner myself but being as your already slamming down 230hp and a solid 210lb/ft tq curve your probably fine.

off -topic: How's the drivabilty/gas mileage with your current 3.2 set up? I noticed I'm getting a solid 27mpg with mine but wouldn't want to hurt that number too bad with cams...

-Josh

 

[Sho Amo]

I would just get a tweecer. Your 80mm maf tune looks horrible, and way too rich. From my experience (which is limited anyways), sho's actually like to run towards stoich (14.6). You could really benefit from a good tune. Im sure that you could get it around 250whp with the setup you have.

Do you have a wideband?

 

[jayro]

off -topic: How's the drivabilty/gas mileage with your current 3.2 set up? I noticed I'm getting a solid 27mpg with mine but wouldn't want to hurt that number too bad with cams...

-Josh

Drivability is fine. With the lightened flywheel and stage 3 clutch I had to get a "feel" for it again. I haven't checked my milage yet. Since a lot of my driving was "seating the rings" along with running extremely rich I am thinking my milage is pretty bad right now. In theory when you increase the performance of the engine you are making it a more efficient air pump. With this in mind if, and that is the big "if", you can keep your foot out of it your milage should be just as good or better. Of course that's just the theory and doesn't hold true in all circumstances.

 

[rubydist]

for most n/a engines, max torque is achieved w/ an a/f ratio of around 12.5:1. as mentioned above, the SHO engine seems to be fine with a little leaner than that, but definitely do not want to be richer than 12.5:1 unless boosted.

 

[jayro]

I would just get a tweecer. Your 80mm maf tune looks horrible, and way too rich. From my experience (which is limited anyways), sho's actually like to run towards stoich (14.6). You could really benefit from a good tune. Im sure that you could get it around 250whp with the setup you have.

Do you have a wideband?

Yeah a tweecer would be nice, it's just not in the cards right now. I don't have a wide band currently. It is on my list for the next few months. They are using the wand they stick up the tail pipe( they didn't even buy her dinner first). We are working on a new tune. The 3.0 had a smooth a/f with the 80mm. It was the exact same lpm, so I think the change has to do with the change in displacement and the bigger injectors.

250whp would be awesome... Running the numbers,if torque could come up a couple of pounds and I could get the power band to carry out another 600 rpms 250 could be possible.

 

[Sho Amo]

spinning it up to 8k might help too. i know those cams like high rpms.

 

[whiteguy3]

I run my second gear out to about 8k with my tri-flows. I'm running in 10's a/f wise too though. I've got to lean mine out too. Seeing that graph really inspires me to get some tuning done. I have the 80 MAF leaned out (the entire curve) 17% per axianator's suggestions on ATX. I would lean it out up top a bit and see where that gets you.

Unless boosted, being in the 10's a/f wise is considered extremely rich. Your probably lean at idle though, that correct?

 

[jayro]

I usually shift about 7500. This keeps me in my peak power. With a good tune the triflows seemed to peak about 6800 rpm and then carry the power out a lot more, rather than dropping off quickly. At 8k it is still pulling hard.

As far as being lean at idle, isn't that normal. It's basically running at no load, then richens up as soon as there is throttle applied.