hi guys, before i owned my (current car) 2002 nissan altima SE, i owned a 2001 Mustang GT which was first using a Vortech supercharger, and then a single turbo kit. We ALWAYS tuned to mid 12's to low 13:1 range.

But now I run n20 on my altima (100whp shot) and i've noticed that all vq35DE forums are all saying to tune WAY lower than that. I see some people tuned in the 10:1 range to high 11's!!!! Is there some reason for this I'm not aware of?

reason I ask is because along with my J&S safeguard I want to purchase a dynotune air/fuel switch which is basically a digital a/f guage which aslo has a switch which turns the nitrous system off above 13.5:1 and below 12.0:1 but by the sounds of things i should be tuning in the low 12's, high 11's so my system would be turning off ALL THE TIME!!!

can someone explain why it is you guys do this? I know rich is safe, by why SO rich?

 

It's a band aid. The Vq runs alot higher compression and the factory timing tables are alot more aggressive than the Mustang. Those items along with better design allows our 3.5L make more power than the 4.6L. The extra fuel doesn't burn it asorbs heat to stablize the combustion process. If you put lower compression pistons and remap the timing you can run close to the normal 12:1 ratio for FI.
Gary

 

ahhhhh i see. although I don't think the 3.5L makes more stock, neither makes more before needing a rebuild (around 450-500rwhp) and both have the 1 shitty limiting factor. Crappy rods and rod bolts

 

2004 Ford GT Mustang 4.6L = 260 hp with 302 lb -ft. of torque

350Z 3.5L = 287 hp with 274 lb -ft. of torque

I think 450whp is the outer limit for our rods on the 350z. Don't think you could count on reliability for a daily driver boosted to 450hp. A member of this fourm posted a Dyno sheet with that magical number although.

 

yeah thats what I mean, gt has more tq, z has more hp, evens out. Both can do 13.8-14.2 1/4 mile stock. BUT GT has 8 cylinders, and probably why it can handle 450-500rwhp (500rwhp being very risky, i blew mine at 480rwhp).

 

With F/I peak HP will occur between 11.4-12.4 A/F. Most F/I tuners will recommend roughliy 11.5:1 as a safe target. N/A cars are usually tuned to 12.5-13:1. And given the weak state of the stock VQ motor, most of us are erring on the side of too rich.

 

I posted the dyno with the magical 450 number as well as Skidazzle at 453. Bear in mind, we are not daily driving these cars at 450 rwhp. We both prefer reliability for driving around which is between 387 and 400 rwhp.

FYI, Skidazzle and I both run in the low 11'a for A/F.

 

my tuner sed he shoots for 11.25 for all f/i cars..... 8 cyl or VQ not withstanding...

guess its the safe thing todo (as mentioned above), and the heat of the summers here sure dont help any...

im sure we all could make a measurable amount MORE of power, if we leaned to the 12's, but i know i wouldnt risk it...

S

 

I'm in the 9's for the rotary. This thing eats gas. It basically dumps fuel into the rotor chamber with 1300cc injectors and gas prices aren't helping either.

Victor

 

WOW 9's !!!!

 

why do rotary's have to run so rich? Is there something inherent in the design of the rotary engine that neccessitates such rich fuel levels?

 

because they are time bombs

 

I had a highly modded FD(400 rwhp) and loved it. The biggest reason is due to the shape of the "chamber" in a rotary. It's very long. It's a pretty poor shape for a combustion chamber. The air fuel at the far end has plenty of time to heat up and pre combust waiting for the flame front to get to them. Plus a rotary can not take any knock at all, the apex seals break very easy with knock so to cover your butt you run rich as hell.
Gary