Low Dyno #'s, running rich?

[skytower31]

So I just got back from dynoing, and was kinda dissapointed. The last time I dynoed was on a mustang dyno with just the 345hp alteration package on my firehawk with a cutout open. I put down 325.5rwhp. This time was on a dynojet, still stock 345hp alteration but through the GMMG catback and the airflow smooth bellow and put down 304.7rwhp. Didn't have A/F on the first time I dynoed, but this last time it was between 11-12 during the run which they told me was a little rich. Also, each time the gragh had little spikes throughout the curve which one guy said was a timing issue?

Basically, can someone tell me what is going on? Are Mustang Dynos known to dyno higher? Is between 11-12 a rich A/F that would cause me to loose 20rwhp? What does the spikeyness mean? Please help! I am fine if my car is actually only making 304.7rwhp, I just want to know what it is actually making! :mad:

Here is my dyno chart...any suggestions would be great!

http://firehawk.jonbroomfield.com/dyno.jpg

--
2002 Black Trans Am Firehawk M6 #1335 (http://firehawk.jonbroomfield.com) :burnout:

Mods: GMMG, Air Flow Smooth Bellow, SLP Bolt-on SFC's, SLP STB, LSS, 5% Rear Tint, DEI 530T Auto Up/Down, !CAGS, !PAS

Factory Options: Traction Control, M6 - Hurst Shifter

SLP Options: 345hp Alternation, 1LE Suspension, Auburn High Torque Differential, Chrome Wheels, Firehawk Floor Mats & Deck Mat

-- You know that nerd you made fun of in high school, well it turns out that he does end up with the fast car AND the hot girl!

[jrp]

mustang dyno's are known to dyno lower but more accurate then a dyno jet.

do you have the graph of the first dyno? post that up if you do. you are on the rich side and would gain some ponies by leaning it out some. i'd atap your car and note your timing and any KR.

[skytower31]

Here is the graph from the 1st dyno. Would running a little rich drop me 20rwhp? I HIGHLY doubt that the GMMG is more restrictive than the SLP dual/dual which I pulled a 320rwhp through. Also, I think the first place I went was a Dyno-Jet. They call it a Dyno-Jet Chassis Dynometer. It is the kind that is built into the floor to where the one I was one today was up on a lift. Also, today was very rainy and wet...could that have done anything? Thanks for any thoughts you have!

Also, how can I adjust my A/F?

http://firehawk.jonbroomfield.com/dyno1.jpg

[jrp]

you can adjust you a/f ratio with a MAFT, predator, edit, or hp tuner. the MAFT is the simplest and cheapest bet though.

[skytower31]

Do you think adjusting it would give me my 20rwhp back?

[jrp]

a bit, but not 20rwhp. hard to say what the differences were between the dyno's. to bad you dont have any track times or anything to compare a before an after. try and atap your car like i said and if nothing is apparently wrong dont worry about i t, dyno numbers arent something to get hung up on, its a tuning tuning, nothing more.

do you feel a loss of power? also was the cutout open this time around as well. also note the weather has been shitty this weekend too.

[skytower31]

I don't feel any loss as compared to the dual/dual. I don't have the cutout install on the GMMG, so I can't compare that way. I am not too worried about it, and yeah, track times would be good to have also but I have never run at a track before so I would need some practice before getting consistant...but anyway, just trying to figure out what is goin' on with my car...thanks for the help :D

[jrp]

well theres half your answer; cut out vs no cut out. theres hp loss by no cut out on the GMMG setup.

[skytower31]

But I figured the GMMG would flow as well as the slp dual/dual that came stock. I pulled 320rwhp at Brother's Performance through the dual/dual with cutout closed and only 305rwhp through the GMMG at Strictly Dyno. That is what doesn't make sense. I figure 1 or the 2 machines is off..I dunno, not too worried about it. If another dyno day is setup at Brother's Performance, I'll dyno there again with the GMMG to see. I wish I had A/F from Brother's. Oh well.

[jrp]

my reply from ls1tech

hmm, if theres no timing being pulled cuz of KR, and theres no mechanical problems, then i'd say the differences are just in the dyno calibration, time, and day.

[skytower31]

Yeah, we need to keep this one 1 board. Haha!

[jrp]

as far as timing and KR:

KR or Knock Retard is caused by vibrations in the engine block and detonation. In the event either of these are detected by a knock sensor and a signal is sent to the PCM and the PCM will reduce timing to protect the engine.

Detonation occurs when the air/fuel mixture is compressed and the temperature goes up. The more compression, the higher the temp. At some point, the fuel may spontaneously ignite prior to the spark plug firing. This is detonation and it is very bad for an engine because it often occurs just before the plug fires. You then end up with two flame fronts in the cylinder that crash into each other which can crack pistons and rings, etc.6

Octane is a measure of how much a given blend of fuel resists detonation.

taken from install U

[Black02SS]

Little FYI. On a dynojet I put down 380hp, same mods on a Mustang netted me 335hp. On that particular dyno, most stock ls1's average 260-270hp.

[skytower31]

Is there anyway I can tell just from driving the car if there is some KR issues? Or is that something that would have to be atap-ed?

[killer01ws6]

if it is detonating hard, you should be able to hear the marbles in the intake sound.

I would try to go back to the fist Dyno under simular weather conditions.

Seeing dynos are only a good baseline anyway, if possibel it is a good idea to always go to the same one.

[killer01ws6]

Originally posted by skytower31
Or is that something that would have to be atap-ed?

If you know anyone with a predator they can do live readings for you, can't adust anything.... but can look at it.