Beauty! I agree!

 

At what mileage did you do the spark plugs? Did you notice any difference?

 

Will let you know tomorrow, actual install is happening then. Mileage is 65K. Part of the recommended service for 60K is spark plug replacement.

 

Any downside here Rolla? I recall a convo between you and lubouxracer I think about spacers. I like the way it looks but want to consider any implications as it must change suspension geometry. Especially at 20mm vs something less aggressive.

 

I need to install my spacers. I got 20mm in the front and 15mm for the rear.

 

Nope. My personal experience of over 1 year are very positive. No downsides. I will get the first alignment done at the dealership next week so I will see what the numbers are. Car feels very stable and tends roll less over the sidewalls (which is what I wanted as a workaround till I change the tires). This is mostly because of the center of the contact patch gets pushed slightly out so the cornering downward forces directly line with the center rather than the sidewall. Steering feel/weight does not change much. Just have to be careful on tight roads with curbs etc. Just have to make sure they are torqued properly and the wheels are torqued properly as well. I use 80 ft-lbs.

 

Thanks - it looks great

 

One thing I see a clear difference is when the shift shock happens at redline/rev limiter (manual/sport+), without the spacers, rear tires used to get unsettled, but with the spacers on it kicks harder in the back of the seat without any movement in the chassis/rear suspension. I put 38R/36F to keep the rear as solid as as brick while allowing some front roll under cornering to make the front end bite/grip. I don't doubt there might be some negatives of spacers, but in my experience, I have not seen any yet. I will look at the alignment before/after next week. Knock on wood!

 

Installation done. Haven't done enough sit time with car but my first impression is the car is different.

The most surprising thing was the engine sound. Once my Indy installed the spark plugs his first comment was the engine sounds different and he picked up on that instantly, I thought to myself "you got to be crazy". Sure enough the minute I jumped on the freeway the engine sound was a lot more pronounced and deeper. Very unexpected!

At high rpm the car seemed to pull a lot faster in a very strange way. I need to do more sit time and report back but certainly car is bizarrely different.

According to Denso their tests showed increases in HP 10 to 15HP but I took that with a grain of salt but now I'm beginning to wonder if that really is the case.

My Indy also commented he has never in his profession seen a spark plug with such a tiny center electrode. He's installed a couple HKS racing plugs but stated those have had issues with throwing check engine lights.

 

koni
was the plugs a different range? Or oem spec?

 

Konichiwa3,

part # for the plugs?

 

Denso recommends IKBH20TT, but those are not racing plugs. Probably IKH01-24. A little cold, but not horribly cold. I wouldn't expect a super long service life with these plugs, but making more power is intriguing. I've never had that be true except when the ignition system was less than stellar and a better plug made up the difference in getting a decent spark.

 

^^^
Lance,
colder?

 

The bigger the number on a Denso plug, the colder it is. Racing plugs are typically colder than street plugs because they're expected to run at a higher load than the average street driver, and the likelihood of carbon fouling under racing conditions is much smaller. The second link is the manual with all the information about Denso plugs of all kinds. Worth a read if you haven't learned a whole lot about spark plugs. The manufacturers are pretty awesome at providing solid technical information to the public unlike a lot of other industries.

https://www.denso.com/global/en/prod...sic/heatrange/

DENSO_TM_H1H4 - t-manual.pdf

 

Sorry guys for the late follow up but lobuxracer has got you all covered. His information is spot on.

Yes, they are colder. Stock is 20, this are 24 hence the part number IKH01-24. They fall nicely in the middle between a hot plug of 16 and a cold one of 31.

I wouldn't be worried about fouling this colder plugs as IMO RCF engine runs pretty darn hot, also this particular spark plug has Denso's patented spark cleaning pocket technology to burn off any carbon deposits.

Got more time with the car today. Definitely the car is accelerating noticeably harder. The character of the car has changed, the rev climbs a lot quicker between the mid to high rpm. My thoughts are combustion is highly efficient at the high RPM's with this spark plug, producing more power.

The deeper sound of the engine is still there and it's unmistakable.

They are a lot pricier and just as lobuxracer stated, shorter life span. Service interval is 30K as opposed to 60k for OEM.

All I can say is I'm very pleased with how all this turned out.

And the cherry on the cake I expect better MPG.

Below are a couple of links for those interested. You can thank me later as this was weeks and weeks of research since this Spark Plugs have never been discussed on the RCF platform yet it turns out it's quite a favorite among engine tuners.

Denso

http://densoautoparts.com/Portals/De...m-brochure.pdf

http://densoautoparts.com/spark-plug...aspx#undefined

http://densoautoparts.com/iridium-ra...lug-components


TRD

https://www.trdparts.jp/english/parts_plug-racing.html


Where to purchase along with specific part #


Excellent info by Brisk about heat range

https://www.briskusa.com/spark_plug_...at_range_chart