Iridium Plugs

[jss06c6]

Originally Posted by Marc Haibeck

Denso has recently released a spark plug that is specifically designed for wasted spark ignitions. It has a platinum tipped negative electrode. This addresses the erosion issue associated with the negative polarity spark that half of the cylinders have on wasted spark systems. In addition the negative electrode has a pointy tip that provides an excellent electric field.

The model number is IT20TT. Some parts catalogs only use the part number 4714. It is the same heat range as the OE spark plug and has a tapered seat which is a universal fit for all LT5s.

This is an expensive high mileage spark plug, good for at least 40k miles. I agree with Paul that the dirt cheep ACDelco 41-602 works great for 10k miles.

Marc, thanks very much for this tip!!

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[jss06c6]

Originally Posted by XfireZ51

Steve,

I'm using the the FIC injectors which are supposed to be balanced to within
+- 1%. However, did not have them flow checked.

Dominic, with new FIC's I wouldn't have worried, but recent experience with "aged" Bosch injectors told me to have them checked. Keith Tais at Fuel1 told me he had a heck of a time getting them cleaned up. He wanted to get them below 2%. As you'll see on the attached, they didn't quite get there, but very close.

I then match the lowest primary with the highest secondary for a cylinder pair. I continue this sequence until I have the highest primary with the lowest secondary injector. I then assign the highest combined flow rate pairs to #8 & #7, working my way forward to #2 & #1 which will have the lowest combined flow rate.

I also had them flowed at 50 psi vs. 43 psi.

Obviously you can't use injectors that are way off! My experience so far delivers nice fuel balance across the cylinders with optimal combined flow when secondaries are kicked in (or when running on engines with secondaries deleted). Bank to bank fueling seems to be closer as well (read BLM left and right) provided your O2's are good.20201102_055510.jpg20201102_060041.jpg

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[Hib Halverson]

Originally Posted by Marc Haibeck

Denso has recently released a spark plug that is specifically designed for wasted spark ignitions. It has a platinum tipped negative electrode. This addresses the erosion issue associated with the negative polarity spark that half of the cylinders have on wasted spark systems. In addition the negative electrode has a pointy tip that provides an excellent electric field.

The model number is IT20TT. Some parts catalogs only use the part number 4714. It is the same heat range as the OE spark plug and has a tapered seat which is a universal fit for all LT5s.

This is an expensive high mileage spark plug, good for at least 40k miles. I agree with Paul that the dirt cheep ACDelco 41-602 works great for 10k miles.

Actually, the IT20TT has been around for a number of years and, like Marc says it's a great choice to waste-spark ignition systems because it's a "iridium/platinum" plug.

The Denso 20 heat range is about the same as the NGK 6 and the old ACD 1 heat range. It's a good choice for LT5s with two exceptions: 1) it's too cold if the car is a show car which seldom sees aggressive driving and does experience frequent starts-without-warm-up and/or short trips. If that's the duty cycle, I'd use the IT16TT and 2) it's too hot for serious track use. For that you need the Denso 22 heat range and unfortunately there is no Denso IT22TT. If you're NGKm you need the 7 heat range.

When I owned Barney, I ran Denso IT22s (iridium tip) all the time and never had a problem other than more rapid errosion of the side electrode on the half of the cylinders which had negative polarity. I just changed those four plugs more often.

Lastly, someone said earlier that iridium plugs "run hotter". Please, post some facts which support that statement.

[XfireZ51]

Originally Posted by XfireZ51

So what heat range are you all running? I?ve read that Iridiums run a bit hotter than equivalent copper plugs. I?m trying out BKR7Es right now which SOTP seems to like. Also appears to have helped w random knock.

Hib,

As you can see from the quote, I stated I had read that equivalent iridiums ran a bit hotter. I interpreted that as having a hotter spark.

[Rodder]

Be aware of counterfeit NGK and Denso spark plugs when shopping on the internet. Try google fake spark plugs. Use an authorized dealer so you know what you getting.

Used FR1LS 035 and now Ngk bkr7e-11 044. Never logged to compare but runs fine with both and my driving style.


Thomas

[XfireZ51]

Originally Posted by Rodder

Be aware of counterfeit NGK and Denso spark plugs when shopping on the internet. Try google fake spark plugs. Use an authorized dealer so you know what you getting.

Used FR1LS 035 and now Ngk bkr7e-11 044. Never logged to compare but runs fine with both and my driving style.


Thomas

Thomas,

Have u looked to see how they are burning?

[Rodder]

I can get a pic. I have a joint problem that put me offside now and then, like now, but I get to it.

[BigJohn]

Originally Posted by Rodder

I can get a pic. I have a joint problem that put me offside now and then, like now, but I get to it.

I hate when that happens!

[Karl]

Another vote for AC/Delco 41-602.

I swapped mine earlier this year and gapped new plugs at .050. and the car seems to like it even better than the .035 gap.

Can't beat the price and they are good for 10k miles.

[Hib Halverson]

Originally Posted by XfireZ51

Hib,

As you can see from the quote, I stated I had read that equivalent iridiums ran a bit hotter. I interpreted that as having a hotter spark.

A plug that is a hotter heat range does seldom means it makes a "hotter" spark.


Iridium tipped plugs in a given heat range do not run "hotter" than a non-iridium plug of the same heat range.