Scooter

ok, i'm very confused on something...

as far as headers go, u want a rich mixture in order to get max performance, right???? leaner riding will get u better fuel economy but at the expense of performance, right???

as far as iridium plugs go, "the leaner the air mix the more difficult the firing. The greater the ignitability limits, that is the leaner the air mix in which a plug can spark, the better firing performance a plug is said to have." (source Denso.co.jp)

so what am i missing here???

the basis of me creating this thread was in response to Zapata's seemingly lean riding after getting headers AND Denso iridiums while at the track he and i ran 14.9's (i only have CAI, while he has CAI, headers, iridiums, and exhaust)...sounds to me the headers and iridiums cancel each other out, while the exhaust is is marginal gain...that leaves us with CAI's (Zapata's AEM and my Xephyr).

JRock

Obviously something is just wrong with his car (most likely the actuator) because plenty of people here have pulled 14.6-14.7 with headers. Plugs and headers don't cancel each other out, don't be silly.

Bluto

I thought the issue with our stock plugs was overall performance was sacrificed for longevity (100k miles). How do you measure the total performace of spark plugs? I'm sure it is more than the lean ignitability limits.

How is the air mix on our cars determined anyway?

TypeSKid

If he's running a 14.9 with all that shit then he's a shitty driver, or his actuator is FUCKED!

spiroh

I have the iridium plugs, and headers. I gained about .2 with the plugs and pulleys.

Zapata

Ok. Apparently we have two the brightest tuners in the world here. Jrock and TypeSkid...... No my actuator is fine and no i'm not a shitty driver. Jrock you don't even have headers so i think you should refrain from attempting to troubleshoot the issue. TypeSkid, what kind of tires to you have? What times have you run?

3.2cl-s

can you post both time slips side by side, then maybe you can see the problem with his car...

Zapata

Time slips are indicating that i'm not getting traction. I'm spinning through first gear. Our cars NEED a good 60' time to have low ETs. I haven't been able to break 2.4. Power up top is good.

Nashua_Night_Hawk

Break torque to 2k rpms but do not go WOT out of the hole, once rolling floor it! and do run-after-run is best!

Zapata

I won't BRAKE torque hehe. Yeah, need to get more run the car a bit more and get more data.

JSuppi

Zapata,
Good decision on refraining from the brake torqueing. That could cause some serious havoc (I will definetly vouch for that) on your transmission.

I am also had a hard time breaking the 14.9 1/4 mile barrier, and I had CAI, Headers (but also the shitty ass stock Michelins). I have yet to go back out to Baytown with my Yoko's, and don't plan on it either.

JRock

Nope, not at all. Just because I don't have something installed doesn't mean I can't discuss it, wiseass.

Headers work regardless of whether your car is running lean or rich - they exhaust the pulses better than stock exhaust manifolds no matter what type of pulses they are. If you are pulling the same times a stock CLS is, your car has an issue and it certainly isn't freer-flowing exhaust pulses.

If your actuator is fine and if you're getting enough traction, I'd check those plugs. Could be gapped wrong or maybe you have some minor detonation that is retarding timing.

Grow up and stop bringing up irrelevant facts as an excuse to ignore suggestions from fellow forum members.

Zapata

Nah you made a declarative statement about something you don't have FIRST hand experience. Of course that shouldn't restrict you from discussing a topic but it should be left at discussion and not a diagnosis.

I thought it might be the plugs but PAA installed them. They are falable but i'd like to give them the benefit of the doubt. I have a 22.5k service coming up so i'll have'em double check then. I'd like to get the car onto a dyno and see what kind of power i'm putting down.

JRock

Nope, wrong. In fact, you're the one making an assumption about something you know nothing about - you're saying I don't have any first hand experience with headers. You don't know that for a fact.

And even if I didn't have "first hand" experience with headers, that would be beside the point of having knowledge of how headers work and being able to comment on them.

Sorry, you lose.

scalbert

Rich and Lean depends on what it is relative to and no, you don't want a too rich mixture. That will also hurt performance.

You really want the leanest mixture that does not promote detonation. The richer you go the cooler burn you have and less power to drive the piston. Too lean an it gets too hot which leads to deto (uncontrolled burn with multiple flame fronts).

What this ideal mixture for power is depends on the vehicle but most seem to be in the 13.0:1 - 12.5:1 range. Richer than this will generally reduce power, leaner than this leads to deto.

As for economy, the leaner you get, obviously the better mileage you get. But emissions issues call for the mixture to be richer. The stoichiometric ratio for gasoline engine is 14.7:1, this is the ratio at which gas burns the best producing the least emissions but not optimal power.

Zapata

didn't know we were in a competition. Having knowledge on how something works and actually experiencing how it works is completely different. Moreover tuning and troubleshooting is something more than just knowledge of the topic. Again, you made declarative statements.

EricL

Yes, thank you!

AS a note, the Acura/Hondas seem to run WOT mixtures all over the place (well, at least the few I've seen). Perhaps a dyno WITH gas analysis would be of some use.

Honda is also well know for being an innovator in the area of combustion dynamics; the idea is to have a rich mixture right around the plug (stratified charge), but have an "stoichiometric" ratio "around" the range Scalbert suggested (no one mixture is "best" when comparing different engines).

If not for the WOT, there are some Honda designs that run at so bloody lean that they need two plugs, modified 02 sensors, etc. for the ultra-lean mixture during "cruising".

Those Iridium's are good for 30K miles and I haven't seen any dynos and pictures of those plugs with 20K+ miles on them. IMO, the biggest impact with spark changes is when you start having trouble getting a "fat spark" to the mixture.

IMO, "special"/"fresh" plugs and multi-spark ignitions "seem" to do more for cars with conventional "wires". Our cars -- with a high energy coil/module sitting right on each plug -- get a lot of enegy delivered to the plug (unless something is broken).

The sure-fire way to check out the "situation" is to have some decent dyno guys check the fuel-air ratio (EGO) at WOT AND do it on more than one run!



Experpt from a Saturn forum page:

"What is "Stoichiometric?"

By now, you have probably heard the term "stoichiometric." This term describes the mathematically "correct" combination of hydrocarbons and oxygen within a theoretical mixture for the internal combustion process. A stoichiometric mixture combines "just enough" oxygen with "just enough" carbon and hydrogen to ensure that all atoms have a mate. This "perfect" ratio has been calculated as 14.7 parts air to one part fuel – or 14.7:1.

In theory, no leftovers result from the reaction if combustion conditions are efficient and if the input mixtures are stoichiometric. In fact, water and carbon dioxide would be the only emissions produced from a stoichiometric fuel ratio in a completely efficient reaction environment.

However, even though a stoichiometric ratio is theoretically the best combination of oxygen and hydrocarbons for a perfect combustion process, in practice, it is not always the best for a specific purpose. One reason for this is that the calculation of the stoichiometric ratio assumes a "perfect" combustion environment in which every available atom is able to find every available mate. Because combustion environments are not completely efficient, there are cases in which fuel ratios will vary from stoichiometric in order to compensate for the inefficiencies. (This is similar to the idea of a "perfect market" in economics in which every buyer and every seller are able to find one another and conduct a transaction. In the real world, neither economic markets nor exothermic combustion environments are perfectly efficient.)

Fuel Efficiency Versus Power

Even though stoichiometric is "mathematically" correct, it is neither the most fuel-efficient nor the most powerful mixture.

For better fuel efficiency, it is possible - and desirable - to "lean" the mixture, or reduce the amount of fuel relative to the amount of air. In fact, maximum thermal efficiency occurs at ratios between 16-18:1. And some experimental high-efficiency motors will run in "lean" mode while cruising. Such mixtures on these motors may become as lean as 20.0:1

This obviously contributes to excellent fuel efficiency. However, such lean ratios also result in very hot temperatures and relatively unstable mixtures. This can lead to detonation under load and is not best for producing power.

For more power, it is actually best to use ratios that are "richer" than stoichiometric – or ratios that use more fuel relative to a given volume of air. It is important to remember that because combustion environments are not perfectly efficient, it is sometimes difficult for every available atom to match up to a mate. This is especially true under high loads. To help ensure that every oxygen atom is used in the combustion process – and thus results in the release of energy – slight amounts of extra fuel should be added into the mixture. This increases the chance of creating the desired exothermic reaction. And it reduces temperatures, which may avoid detonation.

For these reasons, it is generally accepted that ratios for producing optimal power in any motor should be between 12-13:1. And based upon data that SPS has collected, and what we have learned from engine-builder Mark Womack, it appears that maximum power from the DOHC Saturn motor occurs between 12.7:1 and 13.0:1."