Let's talk octane...

Methodical4u · 11-06-2011, 06:56 PM

Quote:

Originally Posted by 370guy

ITB 350. Im liking this more and more!
http://www.google.com/imgres?q=itbs+...1t:429,r:2,s:0

I got an error message... i've been looking into the meth injection for a while now myself.

FL 4Motion · 11-06-2011, 06:56 PM

Quote:

Originally Posted by Methodical4u

what the hell is an IBT?

ITB=individual throttle bodies.

edit: nevermind.

Methodical4u · 11-06-2011, 06:57 PM

Quote:

Originally Posted by Red__Zed

individual throttle bodies

ohhhh, yeah... that looks pricey lol.

370guy · 11-06-2011, 06:57 PM

Basically it allows each indiviual cylinder to have its own intake and throttle body. Pain to tune, but looks sweet!

Google image search ITB 350z

370guy · 11-06-2011, 07:00 PM

Redirect Notice

WOOOOOOOOOOOOOOOOOOOW

Jordo! · 11-06-2011, 08:55 PM

Quote:

Originally Posted by Red__Zed

good post, good info. Octane is always one of those confusing specs for most people. Maybe we should try and get a reference thread together for info on fuels if people would find that helpful?

Thanks

Sure, if one gets started, I'd be happy to offer my 2 pennies

Quote:

Originally Posted by .

ITB's

Wow -- subject change

ITB's work best inside a tuned plenum -- a bunch of horns exposed to the air will be harder to tune.

Generally ideal for throttle responsiveness rather than more power, per se (at least to the best of my knowledge).

Looks cool, but again, will work better inside a tuned plenum than exposed.

Not possible on our motors, or at least it would be hard to make it work...

370guy · 11-06-2011, 09:21 PM

There are a couple of g35s that did it. If you click on my link in the last post you an see one. And yes the throttle response is significantly better. Would love to see someone who has it on our cars!!!

MightyBobo · 11-06-2011, 09:57 PM

But in the grand scheme of things, you'd spend a LOT of money to get ITB's, and tune for it...and you wouldnt get much power at all in the end.

Red__Zed · 11-06-2011, 09:58 PM

Quote:

Originally Posted by MightyBobo

But in the grand scheme of things, you'd spend a LOT of money to get ITB's, and tune for it...and you wouldnt get much power at all in the end.

they're just something to do for bragging rights in most applications. They are horribly impractical.

MightyBobo · 11-06-2011, 10:00 PM

Quote:

Originally Posted by Red__Zed

they're just something to do for bragging rights in most applications. They are horribly impractical.

Yeah. They sure sound cool, and look even better.

Just trying to figure out why people are actually considering them in the thread lol...or methanol injection for that matter. Save that stuff for high HP boosted applications...

Jordo! · 11-07-2011, 10:41 AM

I don't see how you could even do it with DBW... unless the system were already designed for it.

wstar · 11-07-2011, 11:00 AM

Quote:

Originally Posted by Jordo!

As a precaution on a very hot day (again, in-cylinder temps increase the chance of knock), running the car at constant high load on the track, the extra octane might be a reasonable precaution, in that it will prevent power loss/damage from possible knock events, but it will not give you any additonal power than you were already capable of making given your tune.

Incidentially, that is also why tuners will find better power on boosted cars by running a bit richer a mixture -- the extra fuel is not fully burnt, rather it just cools the piston, reducing heat, and therefore quenching possible knock.

Anybody want to add to/amend that?

I'll add a little to this: what I've seen tuning this car with UpRev (various internet posts from dyno tuners, mostly lines up with what I heard from mine) is that on N/A cars, there's not much point tuning the timing on our engine. Whatever you set the tune to is basically just a baseline, and the car adjusts on its own based on knock sensor feedback. To quote from UpRev's own Tuning Guide:

Quote:

On the newer vehicles equipped with VVEL, the ignition advance algorithms rely heavily on knock sensor feedback. In
many cases it is not possible to make the ECU run more advance because as soon as you increase the values it hears
something on the knock sensor and adjusts accordingly. For VVEL vehicles you WILL still have to pull timing for forced
induction applications so that it won’t ping before it has a chance to do any learning. However for NA applications about
all you can do is pull back the high spots and smooth the table out. The ECU will do the rest on it’s own. In our testing
we found that pulling LARGE values from the main ignition table caused a LARGE power drop on the first run, but after a
few consecutive runs the ECU would advance the ignition right back to where it was before based on knock sensor
feedback.

Given the above, I think it's highly likely that if you reset the ECU and put in a little learn time on a higher-octane fuel, chances are the ECU will pick up a bit more timing advance on its own resulting in some small power gains. It might be difficult to manage switching back and forth between race gas and 93 octane this way though, without getting more knock than you want on the way back to 93 (hence it's better to have specific maps as decent starting points).

The track I was at this weekend sells an unleaded 98 (Sunoco 260 GTX. They also had a 110 but it was Leaded). I showed up with a full tank of my usual 93, and topped off with several gallons of the 98 as we went through the weekend, avoiding fuel starve issues. I figured as the heat went up it was good for a little detonation insurance policy, might help clean the engine out a little as well. I wouldn't have been surprised if a full tank of the stuff would net a slight power gain once the ECU adjusted, but IMHO it's really not worth worrying about. By the end of the weekend I was probably running about 40% 93 and 60% 98, and now I'll mix it back to all-93 over my next few gas station trips.

Jordo! · 11-07-2011, 01:01 PM

^^^ Yep, it seems that there isn't much room to add timing beyond the OEM maps.

Yet another reason why higher octane fuels on our motor are only really useful as a precaution for hot laps at the track on a haot day, and even then not critical.

The OEM timing maps are pretty good at self-adjusting -- it's prety hard to get this motor to ping, from what I've been told (then again, see this...

)

11-06-2011, 09:21 PM	#52 (permalink)
370guy Enthusiast Member Join Date: Sep 2011 Location: knoxvile, TN Posts: 298 Drives: 370+Viper+Vette=Fast Rep Power: 14	There are a couple of g35s that did it. If you click on my link in the last post you an see one. And yes the throttle response is significantly better. Would love to see someone who has it on our cars!!! __________________ - TopSpeed - Z1 - AMS - K&N - Password:JDM - Nismo - Evo-R - Megan Racing -

11-06-2011, 09:57 PM	#53 (permalink)
MightyBobo A True Z Fanatic Join Date: Feb 2009 Location: Las Vegas, NV Posts: 8,465 Drives: No cars; only bikes Rep Power: 52	But in the grand scheme of things, you'd spend a LOT of money to get ITB's, and tune for it...and you wouldnt get much power at all in the end. __________________ I don't own a car anymore.

11-07-2011, 10:41 AM	#56 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	I don't see how you could even do it with DBW... unless the system were already designed for it. __________________ Enjoy it. Destroy it.

11-07-2011, 01:01 PM	#58 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	^^^ Yep, it seems that there isn't much room to add timing beyond the OEM maps. Yet another reason why higher octane fuels on our motor are only really useful as a precaution for hot laps at the track on a haot day, and even then not critical. The OEM timing maps are pretty good at self-adjusting -- it's prety hard to get this motor to ping, from what I've been told (then again, see this... ) __________________ Enjoy it. Destroy it.

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11-06-2011, 06:57 PM	#49 (permalink)
370guy Enthusiast Member Join Date: Sep 2011 Location: knoxvile, TN Posts: 298 Drives: 370+Viper+Vette=Fast Rep Power: 14	Basically it allows each indiviual cylinder to have its own intake and throttle body. Pain to tune, but looks sweet! Google image search ITB 350z

11-06-2011, 07:00 PM	#50 (permalink)
370guy Enthusiast Member Join Date: Sep 2011 Location: knoxvile, TN Posts: 298 Drives: 370+Viper+Vette=Fast Rep Power: 14	Redirect Notice WOOOOOOOOOOOOOOOOOOOW