Tune or Possible Problem...

usaf_branham · Nov 27, 2009

I have complained on here before about my horsepower numbers with the kenne bell. 360 rwhp / 410 rwtq... Im having it retuned, but before i do i think im going to put an o/r h-pipe on it and some of those ngk iridium tr6 plugs gapped at .32

when i talked to my tuner he claims it wouldnt make hardly any more horse power past 13* of timing. so thats what he set it at. i argued that kenne bell has their chips set at 17 to 18* of timing on a base kit and claim 400 rwhp, so i asked him to retune it. he said he will but is making me sign a waiver, in case it blows up.

Look at my signiture for my mods, i was expecting to net over 400 rwhp with the kb install, i thought it to be a very realistic goal. Sooooo.....

do you guys think its my tune or do you think i might have something wrong?

btw: i know im losing a couple horsepower with the h-pipe as opposed to an x-pipe but l/t's with and x-pipe and flowmasters sounds like crap.

wmburns · Nov 27, 2009

Please forgive me if I ask questions covered before.

What happens when the KB tune is used?

From my reading at the KB site, the 1999-2004 4.6 uses 23 degress of timing. At first read, it would seam that not enough timing is being used.

The info on the KB site states that 1 degree of timing is worth 3-4 HP. Isn't that your missing 40 HP ((23-13) x 4 = 40HP)?

Also, don't lower rear end gears use some additional HP? I recall that KB recommeds 3.73 for the best 1/4 mile time with their kit.

I also recall reading a tech article describing a problem between customer cars with sizeable differences (20-30) in HP. KB traced the problem to differences in cam timing between mass produced assembled motors.

I am unable to find the article at the moment.

What has KB told you about the problem?

OBTW, I personally would like to do a KB kit on my own car. How is it?

>>from KB site
http://www.kennebell.net/techinfo/general-info/DynoTestVariables.pdf #23

usaf_branham · Nov 28, 2009

Well, here is the thing.

'From my reading at the KB site, the 1999-2004 4.6 uses 23 degress of timing. At first read, it would seam that not enough timing is being used'

that is the max out put timing running a 12.5 a/f ratio to produce the full amt of rwhp with kennebelle's shoot out tune with their "switch chip"

and yes, 1* of timing is worth 3-4 rwhp, approx 10 fly wheel hp

i opted to take a discount for kennebell to not include their chip, due to the fact that they said it would cause more harm then good to use it with my setup (l/t's & cai). so i dont know what would happen if i used the kb tune...

Also, don't lower rear end gears use some additional HP? I recall that KB recommeds 3.73 for the best 1/4 mile time with their kit.

no, rear end gears have no bearing on how much horsepower is being produced... in all actuallity the higher the rear end gear the more torque / horsepower is being multiplied to the wheels... the reason kennebell suggests 3.73's is because 4.10's are too much gear... there are the obvious traction problems, but not to mention, when i went through the trap i was bouncing off the rev limiter. The thing is, the twin screw creates alot of boost at low rpms, so the rwtq jumps off the map and breaks the tires loose, 4.10's compound the problem 10 fold. I put the 4.10's on long before I ever talked my wife into letting me spend 5 grand on the kenne bell kit.

What has KB told you about the problem?

when i talked to kennebell they blamed it on the tune, however, i have read in many places that kennebelle uses a ragged edge tune, (runs rich with alot of timing), where my tune runs great with the a/f (11.8) with only 13* of timing... it just pisses me off that stock 2 valves are making 405 rwhp with the 9 psi kit, and i have a ton more bolt on's.

OBTW, I personally would like to do a KB kit on my own car. How is it?

since hindsight is 20/20, if i could redo what i did, i would have spent my 6 grand (that i refinanced the car for) on a forged rotating assembly, cams, trickflow twisted wedge 2v heads (9.5:1 compression ratio) and probably a non intercooled 6 psi vortech kit with the mr freeze kit and a tune. granted it would have ran me a little bit over 6k but i would bet you i would be making alot more rwhp than i am. not to mention i wouldnt be worrying about throwing a rod through the side of my block... plus once the motor is built you can upgrade the blower set up with an intercooler and pulley.

However, I am happy with the kennebell 9psi kit. the car is fun to drive, and it was a huge difference. i guess it just depends on how much work your willing to do and what kind of power your looking at making.
Kennebell has awesome low end torque and good hp numbers, where as if you did the 'hindsight work', you wouldnt be making serious power (probably 450+ rwhp or more) until after 3400 rpm or more, and you could spin the motor to 6500 rpm where the stock bottom end is only good to 6000... get what im saying?

wmburns · Nov 28, 2009

Measure of success?

Disagree with your comments on rear end gears. While the gear does not have an effect on how much HP is being generated by the motor, it does have an effect on how it is measured. After all, the HP is being measured at the rear wheels. Rear end gears multiply torque (not HP). If it multiplied HP AND torque, there would be thousand Mustang owners lining up to have 4.10's, 5.10's, 6.10's, ...... and so on looking for ever more HP.

The 4.10's are a popular upgrade because so many NA cars do not make good torque down low. The low 4.10's gears multiplies the torque allowing what there is to go further.

It doesn't seam to me that 12.5 is lean. IMO, many tuners run richer because of the difficulty of ALWAYS achieving a specific AF ratio. Running rich adds a safety margin to accommodate the myriad of driving conditions encountered. Sooooo technically you are leaving HP on the table at 11.8.

So for the sake of discussion, say the timing is limited to 18*. Then (18-13)*4=15-20 HP. Changing the rear end to 3.73’s will add 15-20 more. That’s almost the “missing” HP.

The biggest problem I see is in the overall view of the goal and how success/failure is being measured. The KB tune gets to 405 HP with a specific set up. The timing, AF, exhaust, intake, and rear end are part of that. Your set up differs from KB. You are using less timing, richer AF ratio, and lower gears all things that are well known to have an effect on HP.

By your own admission, the current set up makes more torque than traction can support. What if a combination strategy is used? Small changes in the set up along with a re-tune of the human?

What if instead of a new dyno tune, the $$ was spent instead on 3.73’s? Go to the track and see what happens. Look at the change in ¼ mile times. I suspect the ¼ mile times will be improved because more of the power you have will be applied to getting down the track. Isn’t that the greatest measure of success? Otherwise, the HP number becomes just a number to be used for bragging rights.

Also, by your own admission, the current tune drives great. Soooo what’s wrong with that?

I am really not interested in starting a flame thread. I suspect that you have spent a great deal of time thinking about this and have your own ideas on how to reach the “goal”. However, IMO, you are almost at the goal (if not already there). Just a small adjustment in how the goal is measured is needed.

For what it is worth, I would love to have a KB kit for myself. For me, the $$ just isn't there. But remember that you are actually living the dream that some of us are still dreaming about.

Good luck to you.

usaf_branham · Nov 28, 2009

believe me, i thought about spending the money on control arms and 3.73's but i would rather get it running right first.

Tune or Possible Problem...

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