Zex 125 dry shot dyno

[98 Yeller' SVT]

Dyno graph from my recent 125 Zex dry shot install...
www.club318.com/images/brett_dyno_run.jpg

So... I have a little experience in autocross, but as far as drag racing goes I'm kinda clueless.

What do these awesome torque numbers mean as far as 1/4 mile and 1/8th mile performance. I assume it means with traction (obviously) my car is gonna run strong in the 1/4 mile, even stronger in the 1/8, and awesome 60 foots may be possible...???

I guess the real thing I'm wondering is would I have an advantage over higher RWHP cars with less torque in the 1/4 mile? Would this advantage increase in an 1/8th mile?

I think I'm fuzzy on horsepower, torque, and how the two affect performance.

Discuss?

 

[NXGHOST]

As far s 1/4 Mile racing you will be spinning through the 1/8th mile unless you get sticky tires. If you run some slicks with that power make sure you have upgraded axles, Control Arms. Then loosen up the front struts on those adjustables and hold on. With traction you can likely hit a low 12 high 11. Without, expect a mid-low 13.

 

[97cobraheaven]

thats a little low for a 125 shot, the torque is crazy though. i made 370whp (100 shot, 290hp NA) and had was having blow out in the plugs, so i need to go back and retune with regapped plugs. your graph looks real weird, the power should not be falling off like that, it should keep climbing to 7k or close to it. also what was your air/fuel like?

 

[98 Yeller' SVT]

The A/F ratio does this: It's between 11 and 12 from 2500 to around 3500 when the window switch kicks in the N20, then it richens up to about 10:1 till around 5000 and swings back leaner to about 12:1 at 5500-6000RPMs, then richens up again into the 10's just before redline. The line is all wavy, It's steady, then richens, then leans, then richens to redline.

The A/F ratio was as funky as the dyno lines. The SCT tuner that tuned it tried to straighten out the A/F ratio but he said that he believes the Zex management box (that controls f/p through the FPR) wouldn't allow him to adjust the A/F ratio that much. He believes that the Zex system is designed to run the car rich and that it's out of the tuners hands. That's why we made so many pulls, he kept tweaking trying to get it right. In addition, I installed a boost a pump to help the stock 150 lph along, and he said that was also making it more difficult to tweak the A/F.

He said "It's rich, but it's safe". To be honest I'm happy with the dyno numbers... I don't want any more power, I just want to be safe, the A/F is crazy... but he said it's safe...

 

[Mechanic]

Finally.....

What kind of times are you running in the quarter? Im very interested in your setups as I got a bone stock 98 cobra and Im thinking of gears and nitrous to get into the 12's. Are you running stock cams? Did you need to flash tune the computer for the mods?

 

[98 Yeller' SVT]

What kind of times are you running in the quarter?

Dunnoyet, haven't had it on a track... low 12's with traction if I can get the damn thing tuned right. As it is now (pig rich), with the street tires I'll be happy to run mid/high 12's.

Im very interested in your setups as I got a bone stock 98 cobra and Im thinking of gears and nitrous to get into the 12's.

That should do it.
Don't get Zex, as tuning it is a pain in the ass, get NX.

Are you running stock cams?

Yes, mods in sig.

Did you need to flash tune the computer for the mods?

You don't have to, but it'll give you a little more power... plus with nitrous it's a good idea.

 

[Lightning247]

98 Yeller' are you running stock Injectors? If so what's your Duty Cycle look like, and if not what injectors are you running. What's your fuel system comprised of?

How does the Zex system go about fuel enrichment? My Venom system wires into the factory fuel injectors (each wire) and pulses the injectors for more fuel. Jerry says this either isn't working....or isn't working well at all. So all my fuel enrichment on the nitrous is in the tune.

For comparison here is my Venom VCN 1000 Dyno Tune, 80 Shot. Jerry @SCT says i'm out of injector..which is weird because other's are making much more power before running out of injector.

Thanks
Philip

 

[98 Yeller' SVT]

98 Yeller' are you running stock Injectors? If so what's your Duty Cycle look like, and if not what injectors are you running. What's your fuel system comprised of?

How does the Zex system go about fuel enrichment? My Venom system wires into the factory fuel injectors (each wire) and pulses the injectors for more fuel. Jerry says this either isn't working....or isn't working well at all. So all my fuel enrichment on the nitrous is in the tune.

For comparison here is my Venom VCN 1000 Dyno Tune, 80 Shot. Jerry @SCT says i'm out of injector..which is weird because other's are making much more power before running out of injector.

Fuel system is the stock injectors (24#) and the boost a pump (increases voltage to stock pump (150lph))

The Zex kit is supposed to work with the stock injectors. Over a 100 shot is recommended that additional fuel is added (hence the BAP).

Per Zex:

The nitrous oxide that is distributed to the fuel control circuit passes through a small bleed orifice. This bleed orifice provides a reference source of bottle pressure and a controllable source of pressure to perform the needed function of fuel enrichment. Fuel enrichment occurs by conveying this source of pressure through a delivery hose to the vaccuum port on the fuel pressure regulator. This source of pressure on the rubber diaphram of the fuel pressure regulator causes an increase in fuel pressure. This increase in fuel pressure performs the function of adding fuel volume through the engines own injectors. The amount of addditional fuel that is added can be changed by an adjustable metering jet in the fuel control circiut (Zex box). This jet accomplishes the task by controlling the amount of pressure allowed to build in the delivery hose to the FPR. The jet bleeds off excess pressure in the fuel control circuit and vents it through a delivery tube, back to the intake manifold plenum.

I've read that 100 times and I still don't quite "get it". I guess I'm dense....

Is it saying that the FPR is adjusted via the box in order to boost fuel pressure to aquire the needed fuel.

I suppose it's a possibility that the injectors are maxed out, theoretically they are at 95% duty cycle @ 364 bhp from one source I have, and another says 100% duty cycle is 385 bhp.

I'm at 350-380 Rwhp.

When the injectors are maxed out, are they maxed out? I mean, regardless of what this Zex kit is doing to the fuel pressure, regardless of the FPR, regardless of how this kit is "supposed to work" and everything...???

 

[madmatt]

Basically all that says is that when you spray, the control box determines how much fuel to add. It can be altered using a little metering jet that you change. They made that a lot harder than it really is...man. Congrats on the numbers though. Torque through the roof.

 

[Mechanic]

Thanks for the info guys. The zex seems kinda weird how it goes about enrichening the fuel. How does the NX do it? I had a wet system of theirs on an old 5.0 some years back. I liked the componetry as it seemed more heavy duty than my buddy Nos. I want to go with the dry this time because of the IMRC. What gears are you guys running?

 

[Lightning247]

4.10's on the Spray Here...When I get a new Rear End the 4.30's will go in.