dyno results and power loss due to rich condition

[rsilver]

Hi guys, I have posted before on my dyno results but this time I got tested on a dyno jet 268c and asked for SAE net rwhp.( In an earlier post I got tested on a mustang dyno and didn't get an SAE number so it was mistakenly high and overstated the HP )

We did three pulls at 437, 429 and 423hp SAE net rwhp . Torque was consistent right around 400 ft/lbs. I was very very surprised it was this high but noted the afr was in the high 12's!!! the only mods on this car are a K&N fipk and fr500 cat back exhaust. I checked the AFR after installing the K&N because I had read that it might lean out at WOT. My prior dyno runs were in the 11.8 AFR range and my own LM-1 runs showed AFR to be 11.8 to 12.3
AFR was read at the exhaust before the cats.
Before the most recent dyno runs I removed the shroud from the K&N after reading a post from steig that they picked up quite a bit of hp by doing so. By the looks of the dyno numbers that seems to be the case and it appears that my AFR also went up.
I know my current tune is not safe and will be returning to get WOT AFR down in the 11.5 range. Another case for testing AFR after mods...........

My question is this, How much power do you think I will lose on WOT runs with safer ie richer tune? I know leaner makes more power to a point and then it goes the other way. Does anyone have an idea for power loss from say 12.5 vs 11.5 AFR (if any)?? Thanks for reading this and letting me know.........bob


btw we did two more runs the next day and got 440 and 438 rwhp and 408 torque. I sure hope I don't lose too much going to a correct tune........what do you all think?


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[bradlewis30]

were did you get it dyno at, and on what kind of dyno?

Kb 2.4 12psi i got uncorrected 372 tq 359 corrected 428 and 413
on a dyno dynamics dynamometer

i have realy been thinking about going to finishline and getting my car dyno there.

 

[rsilver]

Dynojet 268c at finishline in denver. Great guys...........any thoughts on
power loss after reducing afr to 11.5?

 

[bradlewis30]

i am no tuner, but i dont think you will have a big power loss for the .5 on the air fuel mabe 10 horses at most, what timing are you running i was told because of the elvation i could get away with more on 91oct gas and that might get you back what little you lose. But with my lightning i tryed that and if i drove down to pueblo it would start ping and even sometime around town bad gas i supose so i was always add some type of octane booster.




what was there correction factor

 

[HISSMAN]

I have never heard of a Dynojet 268C.

 

[bradlewis30]

he might have just not heard them right or got the number wrong but I have been to finshline before with truck and they do have a dyno jet and tune diablo and are good guys

 

[rsilver]

sorry guys, I just remembered it wrong. Its a dynojet 248c or thats what it says on the graph. Yes they tune with the preditor and even though I have an xcal2 by SCT, I am using finishing line and buying a preditor from them and will just sell the xcal on ebay.

I talked to johnny today and his thoughts were I would probably lose some wot power but he said some cars actually gained when they had to richen them up. I guess it depends if you are so lean that you are losing power.

I will let you all know how it comes out, gonna re-tune, put on a stealth
stock f-150 HD 3.25 pulley and hope for the best. If I am anywhere near 425 with a correct tune and stock pulley, then I might get to the 440 range, safe, stealthy and retain good relialability. I am currently at the stock timing, and will stay there since I go on long road trips.

With all the kenne bell and whipple cars in denver, not to speek of the sick turbos, I know they can all beat me, but it will still be fun to play with a few other brands with my " stock" cobra...........bob

 

[rsilver]

Update on my "stock" 04 making 440hp and 403tq.We were very very lean ( high 12's to 13afr) at WOT with the stock tune. The only Mods were the K&N FIPK and FR500 exhaust. I checked WOT with my LM-1 before I put on the K&N and it was in the high 11 range. Seemed awful lean for a stock tune and a totally stock car which I bought new. After the K&N, AFR bumped up to the low 12 AFR range. I never tested when I put on the FR500 cat back nor did i test when I took the shroud off the filter. After these mods we did a few pulls on the 248c dyno, most of which were in the 440 hp range with that combination. Way too lean to be safe, but could still be very effective with a safer tune.

In keeping with my desire to be conservative given this is a touring car that goes everywhere, we just put on a ford F150 3.25 pulley and re tuned and are now at 443 hp and 432ft/lbs peak with AFR of 11.5. Got some belt slip at 6200, with peak boost at 11# then dropping to 9#. I would post the graphs, but am not able right now, but anyway, not bad for minimal and conservative undetectable mods. We got almost 50ft/lbs increase in the lower end of the curve with this set up. We also took 2degrees of timing out at WOT given I could be in places with shitty gas and high temps. Tempting to add the timing back in at altitude though, we could get some additional gains.Just an FYI for those who still have realtively stock cars and want to stay that way .

Finish line in denver did the work. The best guys I ever worked with. On time, reasonable, and experienced and loaded with ford race cars, so mine was a no brainer.

Wonder if there is a larger Ford lower pulley that would fit? Gonna check that out. Also, stock plugs with 18,000 miles. They looked fine so we didn't change them and really, other than the dyno pulls, I rarely ran wot, so that probably saved the engine.

 

[Qwk GT]

So the high afr was with it reading at the tailpipes, your a/f gauge, or both.

Maybe because it was at the pipes that you were reading leaner?

Either way, sounds like you have a strong runner. Cool idea from running a HD pulley, but if I were to pulley it, I would have just gone with a smaller one.

Congrats on gettin it worked out.

 

[mu22stang]

I'm trying to sift through a lot of information here, but here's my experience and input. I also ran on a Dynojet 248 with a shrouded K&N FIPK, MRT Catted H and a Flowmaster American Thunder cat-back. My numbers on 93 octane are 427/389 at a supposed 11.7ish A/F ratio. I say "supposed" because my Aeroforce wideband reads 11.0 consistently under WOT and only tickles higher ratios intermittenly. For reference, I had 12.5ish AFR on the stock tune with the aforementioned mods. Either way, you aren't going to notice power losses by backing of the AFR a few points, even if the numbers are slightly lower. If you want more power, get more mods. Don't sacrifice your engine in the pursuit of a few ponies.

 

[rsilver]

The AFR was read at the down pipe before the cats. I had a bung welded in, so all of my runs with the LM-1 and the Dyno were before the cats. Interesting to read someone else was WOT lean with just a few mods and a stock tune. I am satisfied with approx 50 hp and 40ft/lbs of gain over stock with such light and inexpensive mods. Reminds me of the old carb days when a set of headers, manifold and correct carb made for a sweet street car. Some cars respond well to minor mods in the right combination........