machzilla

Welll, just put in my first good dyno test today. Most of you guys that responded to my hp question last week (what will it pull?) were very accurate in your estimates. With 14 degrees on the motor alone it went 301.99 HP and 326 lb ft torque. AF ratio was just about ideal throughout the run.
With 12 degrees advance on the bottle it did 338 hp and 362 torque.
So.... all of you are wondering why a 75 shot only gives you 37 more RWHP. Well, here's where we found out why the ZEX system is touted as being so safe for your motor. During the nitrous runs we had a fuel pressure gauge in line and watched the ZEX controller shoot the pressure up to 68lbs from about 4000 to 6200 rpm. Evidently the ZEX engineers want to avoid the lean out condition at all costs so they compensate with a pressure spike.
We think by juicin it with a 125 shot it may balance out with the heavy fuel spike and make some really nice numbers, of course keeping the health of the engine in mind.
Still, I was pleased with 301 at the wheels. The guys at Alabama Mustang did a great job dialing the car in and said that number is about as good as it gets naturally aspirated on 302 cubes. I guess that's about 340 at the crank. I'm happy with that.
FOR NOW.......

91lxstang

really nice numbers!!

FordMustangXBA

That's about 355 to the crank. Nice numbers bro.

aode08

no its not, you can get 15 more at the wheels if you add 1.7 rollers, which will take your trick flow cam to

.527 intake and .538 exhaust lift .

machzilla

I've heard 15-17% loss for manual tranny and about 20% for the **** pump. Is there an SAE paper or some kind of test some engineer did to come up with the frictional loss numbers?

FullAuto

Here's the old thread:

https://mustangforums.com/m_1990132/tm.htm

I was 20rwhp low on the N/A numbers but I said 340ish on the bottle. I think I underestimated those Edelbrock heads.

One thing I'd like to point out though, your injectors are going to spike like that with that dry kit. They have to in order to support both the motor and the nitrous. Another thing I think I should mention is, I never saw you list injector size. If you're running a 24lb injector you're past the recommend duty cycle for them with the nitrous. If you're even considering going to a 125hp shot because you think it will equal out to a good a/f, you'll probably have a head gasket come out of your motor and inform you that was a bad decision. So I hope you're running a set of 30s. If not, you better seriously consider it.

machzilla

So lets talk about those injectors. If the fuel pressure jumps like that and the AF mixture is running big rich it would seem like the 19 pounders are getting enough and doing their job. I sounds and looks and smells like the motor is not going to lean out and hole a piston.
Are you saying the 19's are gonna get over worked and fail quickly? Or that they're not capable of flowing enough fuel in the first place, becouse what I saw today doesn't support the latter.

92hatchLX

I'm sure that if you've got 19 lb injectors still you are putting them at 100% work load when you're juicin it, I've heard that you need to keep them under 90. You'd probably benefit from 24 lb injectors. But if the dyno is saying that you're not running it lean you're probably fine for now. Sounds like you've got one HELL of a set up there man. I know some guys on here are only making like 260-280 hp with a H/C/I swap, but then again you've got some supporting mods and a nice flowing exhaust and that helps a LOT.

FullAuto

If you're making 301rwhp with a set of 19s I'd say stick a fork in it because you're done! Recommended duty cycles are sometimes debated but generally it's between 80% or 85% max recommendations.

Did you happen to see what pressure they were at N/A? If the a/f was on, they should have been cranked higher than their stock settings to support 301rwhp. With the dry kit (and I'm not a big dry kit kind of guy), I think they should have only been in the 50-60psi range. To me, I'd say they were already on the brink of failure. I'm an EXTREMELY AGGRESSIVE tuner when it comes to nitrous. I do things I would never recommend to my customers and I'm telling you I would NOT run that setup as is again. I'd chalk it up to great luck and upgrade.

And what is it you consider rich? I've dynoed cars that went below 10:1 a/f at 3200 rpm and never came back. That's rich.

Here's a fuel injector chart you can look at and consider. Remember it's using a higer fuel pressure than stock when giving power ratings so that will factor in.


[IMG]local://upfiles/28026/76C766A2E73244198301C7D3157FC8B2.jpg[/IMG]