Kenne Bell Questions...

usaf_branham

usaf_branham

15 Year Member
Oct 30, 2008
927
134
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Boston
#1
Ok, Ive been driving my car with the kenne bell for about 2 months now... Ive noticed a few small things that are sorta strange. Does any one else have these issues.

When im on it hard, and i shift, the car feels like it hiccups... it hesitates between shifts. You can hear it, and feel it. I thought it might be due to the boost-a-pump, but ive watched the fuel press guage, and there are no spikes or anything wierd with that.

Also, if any of you guys tune, i was wondering how what kind of a/f ratio you typically run in a kenne bell car, and how many degrees of timing. The tune in my car has an a/f of 11.8 and 13 degrees of spark, it does make 10 psi around 5900 rpm, and it is a stock bottom end. the guy who tuned it, said its tuned conservatively, and its very safe, but i am only making 360 rwhp... i was expecting more like 400+... so what do you think? I dont want to blow my car up, im just wondering is there more in it. what is the general consensus??? all of my other mods are in my sig.
 
#2
Also, I left the stock throttlebody on there. I have the bbk cold air intake on the car, and im thinking about putting a 75mm throttle body on it. Im sure it will increase my rwhp, but i dont know how much, and im worried about the a/f ratio getting to lean. Like i said its at 11.8 now, what do you think it will go to with a bigger tb?
 
#3
11.8:1 is within the realm of what many tuners target. 360hp at 9psi is on the low side but not outside the realm of reality. Throttlebodies are overrated for a KB car under 450hp.

More hp is all in the tune. As long as you aren't seeing detonation with the fuel you are using, there could be more there.

The stock bottom end is not durable for 400+hp levels. Mine blew at 405lb/ft of torque. Now I am in the process of a 600hp build...
 
#5
32ValveRom said:
Is it more the pistons or rods or just the whole bottom end?
Click to expand...

Pistons and rods. The crank is pretty solid, even the cast piece. For more than 500HP or high RPM the forged Cobra crank would be a better bet but for 6000RPM-max street-driven 2Vs, even blown ones, I'd think the cast crank would be good for 500rwHP and below. Above that power level or for higher RPM the steel piece would be just common sense.
 
#6
I have the same exact hesitation between shifts. KB 1.7L on an 01 GT. Curious if anyone knows what it's from, I hear Cobras have it as well. Doesn't hesitate if you powershift.

Previous set up on 9lbs I put down 373/370. Now on a built motor and 10lbs put down 400/412. As a side note, I would not change anything, including the throttle body, without getting the car retuned.
 
#7
Sounds to me like you have a good tune in it - 11.8 - is fine - most tuners target 11.5-12.0 A/F. 13* is a hair conservative - most tuners target 14* on a 2v with a stock bottom end. I have seen KB 2v cars with the same setup and tune make from 340-400 or so, Results usually do vary for some reason - when we tune cars, we get timing and A/F correct and whatever it makes, it makes. While you might be disappointed somewhat with it, I think you'd be more disappointed if the motor let go with a more aggressive tune in it.

The shift hesitation usually is a mechanical fuel issue - KB used to sell a little 'damper' disk that goes under the FRPS, dunno if they still do. You can also diminish it by removing the one way valve in the fuel tank, but the downside to that is it increases cranking time.

Don
 
#9
This is one I really can't help with but am interested in.

To add some info that may help: My alternator had some bad diodes (good charge but AC Ripple [bad for computers]) and once I replaced the Alt, my bucking decreased and my parasitic drain decreased. Computers were happier but I think they are still not totally happy. Cars are getting so computerized that the smallest voltage variation messes with them. Give me a year and I'll understand the tunes better.
 
#11
GDawg said:
Are you sure...? School me on this... I thought that a 75mm TB was minimum for a KB setup. Plus a 90mm MAF. And a boost a pump or a fuel pump system that can keep up.
Click to expand...
I have a 2.1 KB with the stock TB and intake... KB's figures show a 4 hp gain for a 75mm tb with a 6psi kit, so I didn't bother. The stock intake isn't restrictive enough to bother, granite I threw a K&N in the stock airbox with the silencer removed. Kit comes with a boost-a-pump.
 
#12
usaf_branham said:
Ok, Ive been driving my car with the kenne bell for about 2 months now... Ive noticed a few small things that are sorta strange. Does any one else have these issues.

When im on it hard, and i shift, the car feels like it hiccups... it hesitates between shifts. You can hear it, and feel it. I thought it might be due to the boost-a-pump, but ive watched the fuel press guage, and there are no spikes or anything wierd with that.

Also, if any of you guys tune, i was wondering how what kind of a/f ratio you typically run in a kenne bell car, and how many degrees of timing. The tune in my car has an a/f of 11.8 and 13 degrees of spark, it does make 10 psi around 5900 rpm, and it is a stock bottom end. the guy who tuned it, said its tuned conservatively, and its very safe, but i am only making 360 rwhp... i was expecting more like 400+... so what do you think? I dont want to blow my car up, im just wondering is there more in it. what is the general consensus??? all of my other mods are in my sig.
Click to expand...

Don 95Vert said:
Sounds to me like you have a good tune in it - 11.8 - is fine - most tuners target 11.5-12.0 A/F. 13* is a hair conservative - most tuners target 14* on a 2v with a stock bottom end. I have seen KB 2v cars with the same setup and tune make from 340-400 or so, Results usually do vary for some reason - when we tune cars, we get timing and A/F correct and whatever it makes, it makes. While you might be disappointed somewhat with it, I think you'd be more disappointed if the motor let go with a more aggressive tune in it.

The shift hesitation usually is a mechanical fuel issue - KB used to sell a little 'damper' disk that goes under the FRPS, dunno if they still do. You can also diminish it by removing the one way valve in the fuel tank, but the downside to that is it increases cranking time.

Don
Click to expand...

I may be wrong... but I think I remember reading somewhere on the KB website thate their daily driver recommended tune (non-shootout) is about 11.1:1 A/F ratio with 18 degrees of timing advance at WOT.

Also, I definitely remember reading on their website that the HP gain from higher A/F ratio as opposed to increasing timing advance while staying away from knock is lower than if you increase spark and keep the A/F ratio low enough to stay out of knock.

Double check their website and maybe even call them, but I would shoot for 11.1:1 with 18 degrees at WOT with 91 octane or better.

Try it out and go to the dyno to see how it works.
 
#13
Found the reference. See "Tech and Tuning Tips" on there website.

The POWER (street) calibration is 11.1 AFR and 18 degrees of timing.
The SHOOT OUT (maximum HP with 100 octane) is 23 degrees / 12.5 AFR.

They also show 1 degree of timing to be worth about 4hp and 12.5:1 AFR is about 11 hp more than 11:1.
 
#14
I finally got the shop who tuned my car to set an appointment up with me to retune it... 9 months later....

anyway, when i go on thursday, im getting the switch for the switch chip and having him fix my current tune (driveability issues at part throttle under 2k) 13* & 11.8 a/f and leaving it as tune 1 - everyday driving tune

tune 2 will be 18* of spark at 11.1 a/f - the shop had better do a pull after making me wait this long for the retune so i can see what sort of difference it made

tune 3 = every day tune for 91 octane
tune 4 = tune 2 for 91 octane

tune 5 = 23* at 11.8 for race gas

That is what I am going with unless one of you guys that tune steer me in a better direction. Advice is always good. Thanks.
 
#15
Just wanted to add my 2 cents here i have a similar setup= 2V ported with cobra crank,rods and low comp pistons,2.6 big bore KB blower dual cobra pumps which i would recommend and believe KB recommends with any boosted motor, 60lb injectors, cobra big oval TB and cold air intake. I give this information because my car only puts down 490HP and 444lb/tq at the wheels. I think with what u have u are getting good power but u might think of getting a bigger fuel pump and/or running dual lines to the rails but not really necessary until 20psi of boost i believe. Anyway i get a hiccup when my car is cold and the intercooler temp is below 60Degrees ( not sure that has anything to do with it)
 
#16
fastenough said:
Just wanted to add my 2 cents here i have a similar setup= 2V ported with cobra crank,rods and low comp pistons,2.6 big bore KB blower dual cobra pumps which i would recommend and believe KB recommends with any boosted motor, 60lb injectors, cobra big oval TB and cold air intake. I give this information because my car only puts down 490HP and 444lb/tq at the wheels. I think with what u have u are getting good power but u might think of getting a bigger fuel pump and/or running dual lines to the rails but not really necessary until 20psi of boost i believe. Anyway i get a hiccup when my car is cold and the intercooler temp is below 60Degrees ( not sure that has anything to do with it)
Click to expand...

Curious... what boost are you running? What size pulley? Headers, cams, exhaust? What are you revving too?
 
#17
usaf_branham said:
I finally got the shop who tuned my car to set an appointment up with me to retune it... 9 months later....

anyway, when i go on thursday, im getting the switch for the switch chip and having him fix my current tune (driveability issues at part throttle under 2k) 13* & 11.8 a/f and leaving it as tune 1 - everyday driving tune

tune 2 will be 18* of spark at 11.1 a/f - the shop had better do a pull after making me wait this long for the retune so i can see what sort of difference it made

tune 3 = every day tune for 91 octane
tune 4 = tune 2 for 91 octane

tune 5 = 23* at 11.8 for race gas

That is what I am going with unless one of you guys that tune steer me in a better direction. Advice is always good. Thanks.
Click to expand...

Those numbers sound like a good place to start. I'm not sure what you are doing with tunes 3 and 4, though.

Your tune 1 for everyday driving looks like it would be a good starting point for 87/89 octane. Tune 2 looks like it would be a good starting point for 91 and tune 5 looks like it would be a good starting point for race gas.

I would also recommend you call KB and ask for advice.
 
#20
I know every car is different, and i dont want to scatter my motor. So just to be sure...

13* & 11.8 is good for an everyday tune on 87 octane?

what timing and a/f is usually good for 93 octane?

what timing and a/f is usually good 91 octane?

The reason I want a tune for each is because im in the Air Force and I move around, I would hate to get stationed back in phoenix where i can only get 91 octane and only have the 93 tune. So what do you think?

Tune 1 = everyday tune (13* & 11.8 a/f)
Tune 2 = 93 octane tune (as much HP extracted as possible)
Tune 3 = 91 octane tune (as much HP extracted as possible)
Tune 4 = race fuel
Tune 5 = ??? I dont know what to put here
 
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