Regular Gas in my Q45 - Experiment.

[sijoko]

This pertains to my 95 Q45 T. Since the price of gas is spiralling out of control, I've been thinking about ways to maximize my mileage. I'm in Oregon and recently they started puting ethanol in the fuel and my mileage has changed dramatically. I've been getting around 14 mpg in the city.

So I started with some basic stuff. The oil was changed. I use European Castrol 0w-30. I drained and refilled the trans fluid with Mobil I ATF. I also replaced the diff fluid with Mobil I 75-140w.

The plugs were changed about 8 months ago with NGK Iridiums. The K&N air filter was also cleaned. I also had to adjust my TPS voltage down. It was set at .58. I brought it down to .46.

Even after all these things, I wasn't too happy with the mileage.

Yesterday, I had to make a 90 mile round trip that was mostly highway so I wanted to test out how the car would run on 87 octane. I filled it up before I left and drove very conservatively. If I punched it, the engine would ping but I expected that, so I drove like a grandma. I cruised at around 65-70 mph mostly. Along the way, I saw a Maserati Quattroporte and had to control myself from giving chase.

Okay, so I went there and back for a total of 90 miles. I filled up the gas tank again to see how much fuel I used. It was 3.6 gallons. So that works out to 25 mpg. Not bad.

Here's my idea. I want to hook up water injection that is activated by a vacuum switch. It would turn on whenever I dipped heavily into the throttle. I had a system like this in my Turbo Q45 before it was boosted. It worked pretty good.

The cool thing about water injection is that it prevents detonation so you can run your car on lower octane fuel and it will not knock or ping. Plus, it cleans out the carbon in the combustion chambers. This is proven.

If I can get my car to run on 87 octane without pinging, then the cost of the water injection would pay for itself in about a year and a half.

[pabs324]

I don't know about putting regular in the tank. I did that and nothing good came of it. I have to change the 2 knock sensors all injectors, hoses and such because of it. It probably also has to do with the ethanol in the gas but I suggest that it's a bad idea.

I've learned my lesson and will always put Premium no matter what.

The spark plugs are supposed to be NGK Platinum pfr5g-11 and K&N filters are bad for the Q45.

Joe has the filter for about $10 and the plugs for 8.25 each.Change those and see how that works.

[Q45tech]

If you study your cruise ignition advance you will see it's 40-44 degrees at 60-70 mph steady. Under acceleration it drops to 22 degrees...............but the pinging has already started before you get there.

I am concerned that you are seeing MILD ping at warmish temps, what happen in Summer or up a hill?

Saving 5% won't help when gasoline goes to $6.

Wouldn't it be more economically productive to take a 2nd/partime job to raise the miniscule $3,000- $6,000 for future gasoline...........?

[qship96]

[QUOTE=pabs324]I don't know about putting regular in the tank. I did that and nothing good came of it. I have to change the 2 knock sensors all injectors, hoses and such because of it. It probably also has to do with the ethanol in the gas but I suggest that it's a bad idea.

I've learned my lesson and will always put Premium no matter what

While I agree that premium fuel is a must, regular unleaded had absolutly nothing to do with your injector, knock sensors, hose problems....nothing.

[qship96]

I would think that if anyone is operating their q45 with current knock sensor codes showing{KS need to be replaced} could probobly get away with running lower octane fuel, as the ECU has already retarded timing enough to prevent damage? Running premium will not advance the timing to take advantage of the higher octane until the knock sensor system is repaired.

[qship96]

Why did you use a 75w-140 gear oil in differential ? 75w-90 would show slightly higher mpg

[sijoko]

We can all agree that 87 octane will cause pinging when used in a G50 Q45. That's why I said that in order to run it, one would have to use water injection which will eliminate pinging.

As far as lower octane fuel destroying the injectors, knock sensors, fuel hoses, etc................that is ludicrous. Those are not going to be affected by the lower octane fuel.

Why am I talking about using 87 octane? Maybe it has something to do with the expected $5 per gallon gasoline that is coming our way soon. As the dollar collapses, we are going to pay out the nose for petroleum products.

Right now what I'm doing is for experimentation. If I can get my Q to do 28 mpg, then I'll be a happy camper.

Okay, now let's talk about detonation. I know that if there is no knock, the ECU will not pull timing. It has no idea what you put into the tank. The knock sensor activity is what it looks at to determine if timing needs to be pulled. As long as the knock sensors behave normal, then the ECU will continue on with business as usual. Water injection will eliminate knocking and pinging. That is a fact. Water injection allows the use of lower octane fuels without detonation.

Here's some links about water injection:

http://www.rallycars.com/Cars/WaterInjection.html

http://www.turbomagazine.com/t....html


Modified by sijoko at 10:37 PM 5/3/2008

[qsiguy]

Drive like a grandma and you'll be fine. Water injection would be a good idea. Detonation isn't going to self destruct your motor unless you are putting a decent load on it during detonation. If you are worried about that you could always back off base timing a bit. Of course that will likely drop your mpg a bit but you are still saving money on the fuel. If it were me I'd mod the ECU so you could do a custom tune. You could lean it out considerably at cruise and then make it a bit richer at a load to compensate for the lower octane. I'd also tune the timing for more advance at cruise and back it off at a load, again to compensate for the lower octane. You could also tweak the knock detection area if you didn't want it to mess up your mileage experimentation.

I've been considering selling my little Toyota p/u daily driver and getting a early 90's Nissan truck or car for my daily driver. Then I could crack into the ECU and try tune it for better mileage. Then I wouldn't have to be too concerned about damaging my beautiful VH.

If I tried 87 octane in my Q right now it would self destruct before I made it through a 1/4 tank!

[sijoko]

I thought about doing something like that. A custom program that allowed the cruise a/f ratios to be very lean like 16:1 or 18:1 would be awesome.

As is, the stock program always aims for 14.7:1 at cruise. This is mainly because of the catalytic converters which operate primarily at 14.7:1.

I don't know how long the cats would last at a super lean cruise afr. Most likely they will begin to self destruct.

[qsiguy]

I think the cats would be ok unless you were cruising for a long long time without starting or stopping. With all the tuning I've been doing lately I have a pretty good handle on how the fuel/timing maps work as well as most of the other parameters.

One thing that will happen if you are too lean during cruise is that the ECU will go into open loop which would normally cause it to go a little rich. I had to deal with this condition a few weeks ago so I lowered the cruise afr to make sure it would stay in closed loop. As soon as the cruise afr would get above 15:1 for a short time it would go open loop. It was running fine but I'm trying to get everything working the way I want it while I tune.

If I was shooting for max MPG I could easily lean it up and it doesn't really matter if it leaves closed loop as long as we are maintaining the lean afr we want. You could also tweak the lean/rich O2 voltage set points which would probably allow you to maintain closed loop during these lean conditions.

This is why I'd love to get my hands on a Nissan daily driver in the early 90's vintage. The options are limitless if you want to hack the ECU and experiment.

[maxnix]

The plugs were changed about 8 months ago with NGK Iridiums. The K&N air filter was also cleaned.

Even after all these things, I wasn't too happy with the mileage.

Hmmmm.....no surprise there. At 5%-6% difference between regular and premium, I really don't know why anyone would bother injection a non-combustible liquid which will reduce power further. Seems like you would be better off with a late model Honda V6 designed to burn regular.

Wish I could find that old post again where a NGK representative said the iridiums should only be used with low compression engines.

Don't see how K&N filter could help at all, and there is the oil film liability not to mention inferior particle filtering.

Anyway, good luck, but I don't really understand the benfits of the goal even if you are successful as power and efficiency will certainly be reduced.

[maxnix]

The plugs were changed about 8 months ago with NGK Iridiums.

Here we go! zerothread?id=220

spoke at length with an engineer from NGK here in the Valley, back when I was considering the NGK iridiums vs the platinums. He explained to me that the iridiums are NOT designed for an environment such as the Q's combustion chamnber and unequivocally cautioned against using the iridium plugs in anything but the low compression 4-cyl for which they were degned.

[Q45tech]

Ethanolized gasoline [like old MTBE] fools the O2 into reading 3.5% leaner due to oxygenate so ecu adds 3.5% to injector open time or 3.5% more than necessary. So the engine actually cruises at the functional equivalent of 14.20 A/F......in closed loop.

Remember the ETHANOL for blending already has <5% of the cheapest lowest quality gasoline as a denaturent:Hydrocarbon Denaturant 4.76 maximum ASTM D-48061.96 minimum

http://www.ethanolrfa.org/obje...s.pdf

You might fint this interesting:http://www.ethanol.org/pdf/con...7.pdf

It appears that highway MPG with RFG vs E10 vs E20 depends on the software in place. Whether had been rewritten for E10 as base number or not..................2007 Ford Fusion with E10 sucked [-3.4 MPG] vs RFG and E20........somebody dropped the ball on software!!!!!!!!!!!!!!

Anyway it appears that E10 cost ~~ 0.75 MPG at cruise on older Q because of O2 vs ecu setting say 20 gallons in 1,000 yearly.

Whether saving $80-$100 is worth the time/hassle to perfectly rewrite the O2 normal point is unknown but if gas goes to $6?

"I've had my wideband (AEM UEGO) in for about 1000 miles now and I typically fill the car with Shell's V-Power (93 octane) gasoline. At idle and at a cruising pace I would typically see the AFR on the wideband "hovering" around 14.7 with a swing from maybe 14.4 to 15.0 .

Today, very low on fuel, I filled up with 93 Oct from Exxon which in MA now has 10% Ethanol. For the next few minutes of driving everything seemed fine until I stopped in traffic on a hill and I noticed the AFR hovering around 13.8. This continued at idle or at a cruising pase, sweeping from 13.3 to 14.3 but never in the range of 14.7 again. "

"change your O2 rich/lean Voltage limits. because this will change the range that the ECU is trying to keep the engine running in. The only safe way to do this is with a WBO2 to keep an eye on your AFR while setting this up. Once EVERYTHING is tuned properly it is possible to run leaner than 14.7:1 in closed loop(The ecu will still be running at what it thinks is stoich, you will just be shifting the range a little.)"

[NightRiderQ45]

plugs are supposed to be NGK Platinum pfr5g-11 and K&N filters are bad for the Q45.

Joe has the filter for about $10 and the plugs for 8.25 each.Change those and see how that works.

I have my K&N for two years and I eventually threw it away after I saw a study about it. It was the worst perform air filter in EVERY category. As far as plug, I will purchase mine from AAP and not worry about the shipping charge from Justin. Oh the dealer sells air filters for Y33 for $12 too.

[Victor]

Can you guys expound more on the K&N air filter issue. The only mod on my 94 J30T was a K&N air intake and filter. But the previous owner gave me the old filter housing and air filter in case I wanted to reinstall them.. Should I take the K&N off and reinstall the original air filter? K&N claims in their advertising their filter give a performance improvement

[Q45tech]

Cone filters even with a type of housing to TRY to keep hot engine air out rarely work well..................use a remote thermometer to measure.

When you sell any aftermarket part you learn to lie in creative ways to not get caught. You learn to create false dyno graphs and pay famous people to promote your product. Simple as that. Amazing what people will do for a SPONSORSHIP or to feed their kids.

All aftermarket externals depend on the SCIENTFIC [automotive engineering] IGNORANCE of the young and old buying public.

[maxnix]

When you sell any aftermarket part you learn to lie in creative ways to not get caught. You learn to create false dyno graphs and pay famous people to promote your product. Simple as that. Amazing what people will do for a SPONSORSHIP or to feed their kids.

All aftermarket externals depend on the SCIENTFIC [automotive engineering] IGNORANCE of the young and old buying public.

Just watch one of those K&N televison commercials and tell me where a factual statement is made by the company. It's all "Feels like......" or "Sounds like....."
Modified by maxnix at 3:00 PM 5/5/2008

[NightRiderQ45]

Can you guys expound more on the K&N air filter issue. The only mod on my 94 J30T was a K&N air intake and filter. But the previous owner gave me the old filter housing and air filter in case I wanted to reinstall them.. Should I take the K&N off and reinstall the original air filter? K&N claims in their advertising their filter give a performance improvement

Since the last two post gave you some insight of the k&n filter...I think I'm the only one who actually used one. When I purchased my car, it came with it. I love the way my car used to sound with the k&n filter. Then I started noticing that the amount of dirt that used to be in the bottor of the air filter canister. Then I cleaned my TB and it was soooooo much black gunk coming out. But I figured with the mileage hey, it suppose to look like that. The final straw was when I found an air filter study that PROVED that the k&n filter performed the worst out of all filters. Better yet, take a look for yourself..... http://www.nicoclub.com/articles.php?id=180100 Knowledge is priceless....

[Haitian_King]

I don't know about putting regular in the tank. I did that and nothing good came of it. I have to change the 2 knock sensors all injectors, hoses and such because of it. It probably also has to do with the ethanol in the gas but I suggest that it's a bad idea.

I've learned my lesson and will always put Premium no matter what

While I agree that premium fuel is a must, regular unleaded had absolutly nothing to do with your injector, knock sensors, hose problems....nothing.

What!?! Really? Lower octane fuel doesnt harm injectors? Damn. All this time, I thought that my #8 injector failure last year was caused by my ignorance of the Q's fuel diet and during the first three months of ownership, I filled up with 87. ****.

Gee whiz. So what exactly causes injectors to go?

[Victor]

OK, after reading that report about K&N air filters I took the K&N cone filter and adapter that the previous owner had put on the car and threw it in the garbage can and reinstalled the factory air filter box and a new Fram paper air filter on my J30T. And yes, my oil was extremely dirty the last time I changed it, probably from the K&N filter letting three times as much dirt through as a paper filter would.BTW, anyone know how to disconnect the electrical connector from the mass air flow sensor? Mine is stuck and I didn't want to take a chance on breaking it by forcing it. What comes off, the orange part or the black part? Makes it difficult to change the air filter with it connected.

[bullittandy]

Here we go! zerothread?id=220

This is a six year old quote, second hand from who knows who!! There is no "evidence" absolutely none, of any scientific reason that iridium plugs are not suitable.

Iridiums are worth some horsepower according to a recent article I read.

[qship96]

Any plug that lasts longer than the factory speced NGK seems to be a waste of money, as the factory one already outlasts the valve cover gasket on most Q. and changing plugs when you are doing the gaskets is a no-brainer as you are already in there.

[maxnix]

This is a six year old quote, second hand from who knows who!! There is no "evidence" absolutely none, of any scientific reason that iridium plugs are not suitable.

Who would be Greg Childs, the owner of this board. The plugs haven't changed in 6 years.

Your point is?

[Haitian_King]

Quote »

How SplitFire, Platinum and Surface Gap Specialty Plugs Fare on the Dynoby Christopher A. Jacobs, PH.D., E.E.

This article originally appeared in Grassroots Motorsports January/February 1994 issue. For more info on GRM checkout their website.

------------------------------------------------------------------------ --------

What makes good ignition? Ignition occurs in a modern automobile when an arc is struck and current flows between the electrodes of a spark plug, or when current migrates across the conductive medium in a surface gap plug. While that may sound simple at first, the process becomes progressively more complicated as engineers try to optimize the type of spark plug with the ignition system generating the required voltage.

The amount of voltage necessary to arc the electrode gap is set by the following characteristics:

The size of the gap... arc-over voltage is roughly proportional to the gap sizeThe air/fuel ratio within the gap... the richer the air/fuel ratio (more gasoline vs. Air), the lower the required arc-over voltageThe compression at the moment arc-over is to occur... the higher the compression, the higher the required arc-over voltageThe composition of the electrode... certain metals for all the same conditions stated above will require less arc-over voltage than other metals. For example, platinum requires less arc-over voltage, all other things equal, than does steelThe shape of the electrode... the sharper and more jagged the shape, the easier it is for voltage to jumpThe amount of fouling deposits trying to remove the electron flow from the arc... more fouling deposits and lower resistance to ground pulls more energy out of the spark gap.While it may therefore seem desirable to lower the required arc-over voltage, since without arc-over there is a total misfire and no ignition, low arc-over voltage produces low spark power because spark power is directly proportional to arc-over voltage. That is, by doubling the required arc-over voltage, you double the instantaneous peak spark power, and the higher the spark power, the better the ignition.

All ignition is, therefore, a balance between the requirement to have sufficient arc-over voltage and increasing peak spark power for better, quicker ignition.

What benefits to specialty plugs bring to this mix? One popular specialty type is platinum plugs. The primary advantage of these plugs, especially when used in an OEM ignition system (especially an older system, which may not be producing as much voltage as when it was new), is that platinum will require less arc-over voltage and therefore, particularly in a weak ignition, allows the gap to be jumped a higher percentage of the time.

For example, if at factory gap and with steel electrode plugs, it requires as much as 18,000 volts five percent of the time to jump the arc... due to the changing engine environment and running conditions... and if the OEM only produces 17,000 volts, then it follows that five percent of the time there would be a misfire.

Now, if one installs platinum plugs, which may only require, say, 13,000 volts to arc, the five percent misfiring with steel plugs would be eliminated. Since the ignition output on OEM ignition rolls off as rpm increases, platinum plugs in this case would allow the motor to reliably turn to higher rpm, thereby giving and increase in performance and possibly gas mileage.

The disadvantage of this method of reducing misfires is that the higher arc-over voltage, the better the spark when it does fire. Therefore, platinum plugs will show a performance improvement with a weak ignition because the benefit from reducing the percentage of misfires more than outweighs the loss from reduced spark power.

SplitFire (split electrode ignition) plugs also reduce the amount of arc-over voltage, but they do this in a different way. Rather than using a different metal as the platinum plugs do, a V is cut into the ground electrode, thereby giving three more "pointy" areas for the spark to jump from. It is this increase in the number of pointy areas available to the electrons migrating from the center electrode to contact which lowers the arc-over voltage. All the advantages and disadvantages of platinum plugs described above are inherent with the installation of SplitFire plugs.

While certain geometry's of electrode design, such as splitting the ground electrode, have gained popularity, the principle behind all unusually shaped electrodes is virtually the same. That is, spark likes to jump from and to pointy objects. Therefore, the pointier the object, the lower the voltage to arc over. By the way, this explains why newer plugs often increase miles per gallon and performance: the center and side electrodes are cut sharp, but after being used for many miles, the constant flow of arcing electricity invariably tends to round them off.

Surface gap plugs, which provide a solid-state medium for the electrons to migrate across, generally allow electron flow, regardless of spark voltage. However, they do not allow the air/fuel ratio 360 degrees of contact area with the migrating electron as is accomplished with an open gap type spark plug, but rather only 180 degrees. This is because 50 percent of the electron path is shrouded in the solid state medium. Like platinum and split electrode ignition plugs, they mask a problem inherent in weak ignitions.

Jacobs Electronics, a manufacturer of aftermarket ignition systems, has performed extensive testing of assorted spark plugs. They have noticed an increase in horsepower, on some occasions, with weak ignitions using specialty plugs. However, Jacobs' testers measured no advantage to using specialty plugs with their Energy Team, Omni-Pak and especially their Ultra Team ignition systems, and in some cases noticed a slight loss when specialty plugs, at the same gap, were installed in the place of standard steel plugs. On the other hand, Jacobs has seen a gain with specialty plugs when their lowered arc-over voltage has allowed users to increase the plug gap above that possible with steel electrode plugs.

For example, Jacobs tested a 253-cubic-inch V6 engine, which was slightly modified; the factory called for a 45-thousandths (0.045") spark plug gap. With stock ignition, it produced 168 horsepower. Platinum plugs increased horsepower to 171. SplitFire plugs also brought horsepower to 171. Surface gap plugs increased horsepower to 172.5 - actually a little closer to 173. Jacobs then installed an Ultra Team and replaced the steel gapped spark plugs; horsepower increased to 180.5. Retaining the 0.045" gap, the testers installed the specialty plugs, and the horsepower fell to 178.5 for all three types. The reason for this power loss was because it required less arc-over voltage at the same gap; therefore, the peak spark power fell slightly.

Further experiments with the Ultra Team and different spark plug gaps produced some interesting numbers. With steel electrode plugs, the peak horsepower achieved was 186 at 0.063" gap. With SplitFire plugs, the peak horsepower achieved was 184, but it required a 0.067" gap, which caused some concern about the piston contacting the side electrode. The platinum plug achieved a peak horsepower off slightly under 185, with an optimum plug gap of 0.066".

So what can we conclude? While specialty plugs can mask the effect of an inadequate ignition, so can reducing the plug gap in many cases. One of the true tests of a good ignition is to install a specialty plug instead of a standard steel electrode plug; of the performance of the engine significantly increases at factory spark plug gap, then the ignition was either inadequate or operating in its marginal range.

While these numbers won't apply to all engines, the results are representative and explain the balance between lowered arc-over voltage to assure a spark actual jumped, and increased arc-over voltage to get higher peaked spark power. The general rule is, the better the ignition system, the less benefit that will be achieved from specialty plugs, unless the installer is willing to go with monstrously large gaps.

Naturally, in certain situations, like when you're campaigning an older car (assumably with a weaker ignition) in stock classes where other ignition modifications are not allowed, testing specialty plugs would make a lot of sense. [/quote]On the other hand, I found another article stating that iridium was better than platinum.

New iridium spark plugs fire where conventional platinum plugs fail

Leonard Emanuelson / autoMedia.com

Spark plugs get no respect! In fact, a lot of performance enthusiasts don't give them a second thought. They spend thousands of dollars building the ultimate performance engine then simply screw in whatever plugs the local auto parts store has in stock. The perception is that spark plugs are the lowest-tech components in the modern internal-combustion engine.

Change is GoodIt's no wonder. Contemporary electronic ignition systems have made spark plug replacement in everyday passenger vehicles a thing of the past. And when a racer or high-performance engine builder has a misfire problem, the first thing he does is to add a more powerful ignition system. That's about to change. When the word gets out about the new Denso Iridium Power spark plugs that added 750-hp to Kenny Duttweiler's 450-cid twin-turbocharged Ford, engine builders and tuners will gain more respect for the lowly spark plug.

Kenny Duttweiler of Duttweiler Performance in Saticoy, California is no stranger to making horsepower, especially with turbochargers. After years of building little turbocharged V-6 Buicks that produce in excess of 1,500-hp, he found a lucrative market in NMCA's "World Fastest Street Car" classes building 1,700-hp small-block Chevy V-8s for winning racers such as Bob Rieger and Rod Saboury.

So when he bolted a customer's NHRA AA/Altered Turbo Ford engine on the dyno and had problems making the requisite 1,950-hp (out of 450 cubic inches on gasoline), he left no stone unturned. The engine had state-of-the-art everything—Motech engine management system, MSD Digital 7 ignition system and everything else you could think of. Kenny had isolated the problem to inadequate ignition performance. There was no audible misfire, but the engine made 1,700-hp at 17-psi of turbo boost and only 1,100-hp at 24-psi, indicating that the increased cylinder pressure was causing an undetected intermittent misfire. Reasoning that it was an engine-management or ignition-system problem, he replaced both. However, his Stuska dyno yielded the same results. Kenny replaced spark plugs several times with the best racing and platinum plugs he could find; still no improvement.

Kenny had correctly diagnosed the problem, but as far as he knew, there was no solution. He was already using the most powerful engine management and ignition systems on the planet, and he'd tried most of the "state of the art" spark plugs on the market. Kenny was running out of options and stated prophetically, "Some engines are spark-plug sensitive, especially Hemi-style engines. That's why Chrysler designed dual-plug cylinder heads for their Pro Stock motors in the early '70s. A turbocharged race engine is a variable-compression engine. At 25-30 psi of boost, the cylinder reaches an incredible 2,800-3,000 psi. The higher the cylinder pressure, the harder it is to fire the spark plug. This Ford engine we're developing is the worst of all circumstances. It has a hemispherical-shaped combustion chamber and a 4.670 cylinder bore that is a large area to light off at high rpm. Kenny had no idea that the solution to this perplexing problem would be a new iridium spark plug technology from Denso. In Denso's research for an OEM spark plug that would provide 200,000 miles of service life and lower vehicle emissions, Denso developed a new iridium alloy electrode spark plug. The progression from nickel alloy plugs to platinum plugs in 1982 was a giant leap forward in technology. Denso's introduction of the iridium alloy spark plug will prove to be even more significant, especially for high-performance and race engines. The major difference in the Denso Iridium Power spark plug and conventional platinum plugs, besides the alloy, is the size of the center electrode. A typical platinum plug has a 1.1mm diameter center electrode. The Denso Iridium Power OEM plugs have a .7mm diameter center electrode and the Denso high-performance plugs have a .4mm center electrode.

Size MattersWhat does size have to do with it? Less voltage is required for a smaller center electrode and results in better ignitability. The smaller the electrode, the more centralized the electrical potential is around the electrode tip. The required voltage can be reduced because the level of the electric field is made stronger and local insulation (air gap and electrode surface oxidation) breaks down more easily. The bottom line is that it takes approximately 5,000 volts less to fire a Denso Iridium Power spark plug versus a conventional platinum spark plug.

So why not just make a smaller diameter electrode spark plug out of platinum? It just wouldn't last. The small-diameter center electrode reaches much higher temperatures. Iridium's melting point is 700 degrees C higher than platinum, and laboratory tests have shown that with the same-size electrode iridium, plugs were four to five times as resistant to wear as platinum. Much of Denso's R&D went into finding the perfect iridium alloy (90% iridium, 10% rhodium) that would provide 200,000 miles of service, and working out the manufacturing process to "draw" the electrode into the extremely small .4mm-diameter wire.

The TestKenny was contacted by a Denso representative to test a set of Denso Iridium Power high-performance spark plugs under extreme, real-world conditions. So he installed the plugs and ran the turbo boost all the way up to the 40 psi limit. The dyno numbers tell the story: 1,850 repeatable horsepower, test after test. Kenny admits he's still shy 100-hp from the goal of 1,950-hp, but a camshaft change is in the works to make up the deficit. So what does this mean to the average performance enthusiast? If you are running any engine with high cylinder pressures generated by high-compression pistons, nitrous oxide, superchargers or turbochargers, you may be having intermittent misfiring and not realize it. Of if you have less than the latest, greatest ignition system, you can essentially gain another 5,000 volts of ignition performance by just changing your spark plugs to Denso Iridium Power!

ResourceDenso, http://www.denso.co.jp/index-e.html[/QUOTE]

Slightly off topic of Japanese engines, but it gives more information on the iridium vs platinum.

Then this Nissan/Infiniti board (It's got nothing on NICO) has a thread about the two types of plugs. http://www.nissan-infiniti-for....html

Then I found an NGK sparkplug FAQ here:

http://faq.f650.com/FAQs/SparkPlugFAQ.htm

Though they focus on bikes, I felt the common thread was the difference in platinum vs. iridium.

I had 8 new platinum plugs put in about 900 miles ago. I haven't measured fuel consumption (I really don't care.) so I can't speak on that. I've seen some board members say that they've replaced their plugs and have not noticed any change. After swapping mine out, I felt an immense change in throttle response and acceleration. An associate of mine with a 94 Q also changed his plugs recently and has remarked that there is a difference.

[qship96]

On the other hand, my t3 trip which included replacing ngk platinum plugs with just over 130,000 miles on them with new ngk platinums, both o2 sensors with 202,000 miles on them, pvc, fuel, air filters, knock sensors, plenum job,etc.....and gas mileage didnt budge one bit comparing trip from Md to T3 in Atlanta as compared to trip back home to Md.

Highly doubt if there was no change in 130k plugs as compared to new that using new iridiums instead of platinums will make any difference in either power or mpg

[maxnix]

On the other hand, I found another article stating that iridium was better than platinum........

Important to remember we are speaking of iridium vs. OEM specified platinum plugs in stock VH series V8 here, not other engines.

[sijoko]

Important to remember we are speaking of iridium vs. OEM specified platinum plugs in stock VH series V8 here, not other engines.

So what makes the pentroof combustion chamber in the VH45 different from the pentroof chambers in other high compression engines?

[Haitian_King]

Important to remember we are speaking of iridium vs. OEM specified platinum plugs in stock VH series V8 here, not other engines.

I did remember. I also referenced the difference in engines.

My main focus was on the benefits of iridium vs platinum plugs.

[bullittandy]

So what makes the pentroof combustion chamber in the VH45 different from the pentroof chambers in other high compression engines?

There isn't.

[pouncer11]

I ran 87 twice over the winter and didnt really notice any change, it only pinged a few times. I dont know if it being 12 degrees out would have helped/changed that or not