First post> how to up your compression cheap!!!!!!

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fe=iron

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02 Mazda Protege5> 2.0 5 speed
The factory spark plug comes flush to the combustion chamber using a 19mm reach. By using a longer plug you can gain a noticable power difference. I ran all the numbers to verify clearance, took a while honestly. There isn't much info about the piston to deck distance at TDC, and you can only figure on the effective CC volumn of the heads and piston dish. Plus of course head gasket thickness after crush, lmao. But I did get it figured out and you can make the change for about 15 bucks. All you have to do is use a 06 Dodge 5.7 hemi plug with a
25mm reach, the difference of 6mm or .236 which roughly just over a quarter inch. Clears fine, and has a nice performance boost. I've heard of a few people running a so called "long reach" or "exented reach" plug, thought I'd run the numbers, and find an interchange. Been running my set issue free for months. Enjoy.
 
interesting....nice find. i might wait for a couple other people to try if too though :)
 
lol, safe than sorry right? As long as it's the low comp 2.0 ur good. This mod would be very bad to use with any different piston other than the 9.0:1 dish.
 
Yeah, the NGK ZFR5F11, great plug. But what you are saying is that this so called plug for the Hemi model reaches even further down into the combustion chamber?
 
I would advise anyone with a resurfaced head to not do this. 1/4" longer seems a bit too much to me but that's just me
 
Yeah the long reach plug was a big thing back in like 03? or such. I believe from memory you have TheMan to thank for that particular find :)

The long reach plug AFAIK is just the plug thats used in the fs-ze :)

EDIT: Wonder how much your affecting the burn process, if the plug is too far down in the chamber you wont have proper ignition of gases resulting in a bad burn. The whole reason the long plug became popular is that the gases ignited better resulting in a better burn.
 
I used an ngk, stocked regularly at autozone. As far as a milled head, there is just under .100 clearance from the piston face, so you'd have to mill alot out to have issues. As for burn issues, by increasing the distance towards the piston face; the flame spread should increase intensity given that the intial spark starts close and centered on the piston. As I had previously stated, noticable acceleration, and throttle response. Also I bet you guys didn't know the only difference between the mazda plug and honda b18 are the gap. Most all ngk plugs are pre-gapped. The B18 has a .035 gap, which if you're boosting or running high comp it would be an easy replacement that would save you from gapping plugs between changes. Oh, I forgot, if you're going to run the hemi plug (part #LZTR4AGP for "G" power platinum) use the crush washer off your orginal plug.
 
Alright, so lemme get this straight.. Buy four of these plugs, put em in without changing anything, then enjoy a quicker car?
Do I have to run different fuel?
Will this hurt my car in the long run?
Will it still be fine even though I have a high mileage car(118k)?
What is the compression ratio after this mod?


Thanks! Please answer D:

ALSO! Will this work on my 2.0L Mazda 3? It's a 2006.
 
Sorry to s*** on everyone's parade, but I don't think this is a very good idea. With the long '06 Dodge plug, 6mm of the spark plug's threads will stick into the combustion chamber. Over time soot will build up on the threads, which will make the plug hard to remove and you might end up damaging the cylinder head threads during removal.

The long-reach plugs we normally use (ZFR5F-11) have the same "reach" as the Mazda-specified BKR5E-11's, the only difference is that the electrode sticks out further. There are no threads sticking out into the combustion chamber.

Here are links with pictures of the 3 plugs we're talking about:
Furthermore, the increase in compression is minimal. We're talking about increasing the compression ratio by a theoretical maximum of 0.1 (ie. 9.2:1), but it will actually be less because the spark plug has a good amount of free space around the electrode.
 
I would say if you're burning considerable oil, and you never change ur plugs then yes, it could aquire soot, which is known as carbon build up. I'm not gonna twist anyones arm, use it or not, has no affect on me. Do a little math, and figure the effective volumn of the amount of plug in the chamber, way more compression increase them ur speculated .1, thanks for the input, but I am using these plugs and no one by any means notices a performance increase from adding .1 to a compression ratio. Not even on a dyno. With any performance upgrade there are ups and downs. You guys chose for yourselves. I already have, I'm not saying jump off a bridge with me. I'm saying you can use these plugs to add performance to low comp engine by using a spark plug to decrease the size of the compression volumn. Thanks to everyone.
 
fe=iron said:
I would say if you're burning considerable oil, and you never change ur plugs then yes, it could aquire soot, which is known as carbon build up. I'm not gonna twist anyones arm, use it or not, has no affect on me. Do a little math, and figure the effective volumn of the amount of plug in the chamber, way more compression increase them ur speculated .1,
Click to expand...

I should have posted how I came to that number, sorry about that.

From page 10-4 of the owner's manual (for the FS-DE):
  • Displacement: 1991ml
  • Compression ratio: 9.1:1
That means we have a per-cylinder displacement of 1991/4 = 497.75ml = 497.75cm[SUP]3[/SUP].
At TDC, the volume in the combustion chamber is 497.75cm[SUP]3[/SUP] / 9.1 = 54.698cm[SUP]3[/SUP].

The spark plug you're recommending has a 25mm reach versus the 19mm reach of the plugs we're supposed to use.
They both have 14mm thread size, so the additional volume used by this plug is 0.6cm * Pi * (1.4cm / 2)[SUP]2[/SUP] = 0.924cm[SUP]3[/SUP]

This means that at TDC with the longer plug, the volume in the combustion chamber will be: 54.698cm[SUP]3[/SUP] - 0.924cm[SUP]3[/SUP] = 53.774cm[SUP]3[/SUP]
Likewise, at BDC the volume in the combustion chamber will be: 497.75cm[SUP]3[/SUP] - 0.924cm[SUP]3[/SUP] = 496.826cm[SUP]3[/SUP]

This works out to a compression ratio of 496.826cm[SUP]3[/SUP] / 53.774cm[SUP]3[/SUP] = 9.239 which is an increase of 9.239 - 9.1 = 0.139

fe=iron said:
thanks for the input, but I am using these plugs and no one by any means notices a performance increase from adding .1 to a compression ratio. Not even on a dyno. With any performance upgrade there are ups and downs. You guys chose for yourselves. I already have, I'm not saying jump off a bridge with me. I'm saying you can use these plugs to add performance to low comp engine by using a spark plug to decrease the size of the compression volumn. Thanks to everyone.
Click to expand...

Here's the interesting thing, I (as well as others) could feel a difference when switching from the regular plugs to the long-reach plugs. Specifically I noticed that the car accelerated smoother; there's something to be said for moving the spark lower into the combustion chamber. Your trick certainly does that! ;)

I'm not doubting that there isn't a power increase, I was just trying to warn others that the benefits of this trick might not outweigh the risks. Even a properly running engine (read: not burning oil) will still leave deposits on the hot spark plug, gas doesn't burn perfectly cleanly. So I think people should by all means try this if they're curious (especially those who are already using the long-reach plugs) with the caveat that they might want to remove their plugs every once in a while to make sure they're not stuck.
 
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That is a very prepared answer, I will surely scrap that compression calculator I used. lmao. Also that should clear up any questions about gains. So in any case I would suspose I have mistaken a increase in performance, thinking the ratio had improved it, seems that it would be mostly due to improve flame spread. Interesting, in all honesty that makes perfect sense, since the plug would now be so much lower the flame starts as the mixture is being pressed upwards. Causing a more intense explosion, the largest negative I had questioned, would be the effect of turbulance as the cylinder inatkes, and exhausts. But I suspose it is so little an effect, that is doesn't slow air speed. As there is a performance gain. Be it that you are correct about the ratio, i still dis-agree about the amount of carbon the plug could collect on the threads. I've seen plenty of heads where plug threads are exposed.and the build up is minium at best. With modern detergents in fuel, you won't have much anyway, it would literally take more than the life of the plug to build up enough to even make the plug difficult to remove.but of course every engine performs differently. ( Posted from a tiny keyboard on my phone) definitly thank you for the compression math, I should have just did the equation instead of using a program, but there is a possibilty I may of used a wrong figure somewhere. Regardless, thanks.
 
yep. I'm running them everyday,and I drive close to atleast 100 miles. Somedays more than others, I've been very impressed with difference. Anyone else using em yet that can confirm me?
 
you would have to change your timing a little

i've thought about putting long reach plugs in my v6 to see if i can tell a difference and to help burn off extra gas

but idk about hemi plugs
 
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