I run the B10egv plugs that require you to gap them. I was hanging out at the local dyno yesterday and a piston guy was talking about gaining almost 10rwhp just from changing the gap on his spark plugs.

Can someone explain the theory behind this and also how can you tell if you can safely use more or less gap.

Thanks,
STEPHEN

 

10 RWHP? from gapping? I kinda doubt that. But I've been wrong before. You have to gap most plugs when you get them according to specs. Obviously the larger the gap the bigger the spark - but you also can run into problems of it not firing. Maybe someone could help me out and explain how you want to gap your plugs... for a hotter short spark, or a longer one. -JinX

 

Yea, see thats the info I'm looking for. I know you can change the spark by running different gaps but I'm not sure how you can tell what a good gap is or if you should make it bigger or smaller.

STEPHEN

 

Damn, maybe I need to check out a piston forum for this info haha

STEPHEN

 

If you have the plugs gapped too big it will misfire. You hypothetically would like to run as large of a gap as possible wthout misfiring. But there are exeptions to every rule!
Nick

 

yes you can get more power from bigger spark plug gaps. The problem is you better have an ignition system capable of doing it or it will misfire.

 

I have been running those plugs in my car for almost 2 years and have never gapped them. If the car was tuned with the plugs straight out of the box I wouldn't bother touching them.

 

I have seen people do it before, but whats point??

 

I THINK right out of the box they come with a .024 gap and I've been bending them down and regaping them at .022

Maybe I should just try using them right out of the box since its working for you and its a little more gap that way. I'm running a MSD6a on the leading coils so I SHOULD be ok, its not like its a big difference in gap.....course that might be considered a big differance, I really dont know

Anyway, thanks guys,
STEPHEN

 

I use them for both my pump gas and c16 tunes straight out of the box. I reckon it should be ok.

 

How much boost you running on pump gas?

STEPHEN

 

Then you also get into indexing plugs for those really obsessive. -- SPAuto - you sound like you are using piston plugs with words like "bending them down" to regap. My rx7 plugs don't have the electrode hook, but are flat.

 

12psi on pump gas and 19psi on c16.

 

I use b8ev, b9ev, b10ev (no longer available). dont gap them more than 0.020 but i think RB recommends 0.015 gap.

The good ol b10ev's are no longer avaialble. they are called something else now. I just cant remember what it is.

 

I had a lotus 1600cc twin cam engine. I did a lot of experimenting by indexing / gapping the plugs and was able to get 6 RWHP more out of it by indexing the plugs. Gapping 2 RWHP. This was a full race motor - Nothing below 4200RPM.

 

basically, the larger gap allows for a larger surface area for the spark to jump across, allowing for a more powerful spark. however a lot of boost can extinguish the spark in an excessively gapped plug. you need to take into account your boost and a/f ratios in determining your gap. low boost and lean a/f ratios can be ignited much easier, hence you can gap your plugs more. w/ more boost and richer a/f ratios you have to be careful not to misfire, so you have to gap them down a bit.

 

You obviously haven't discovered the benefits of running such plugs, you should get yourself a set and try them for yourself, the car will run smoother, driver crisper and you will instantly notice a improvment in all over running. B#EV B#EGV and B#EVX plugs are used in motorcross bikes because they are fairly foul resistant, great for running in a rotary where oil is being injected or premix is used

 

The newer ones are called EGV's.
The one I've been using of late would be the BR10EIX's. Those are Iridium plugs made by NGK. So far the results have been very good. They do offer advantages over the regular EGV's. They last much longer in a daily driver and offer much smoother operation during idle and cruise conditions which I believe is due to it's ability to operate at wider gaps and because the Iridium tip is much smaller and conducts voltage easier.
I've been running them between 0.022 to 24 with no misfire problems so far.

crispeed
87 RX-7 TII
9.204@150.47mph
2600lbs
un-tubbed

 

I think you should be able to find a lot of information on this subject from all over the net. This forum is a bit behind on things as far along in tuning as plug indexing and gap. perhaps there is a 1000 HP race engine or nascar forum out there that spends all day on 3HP things like this.
Im sure the information on plugs will apply to all combustion engines not just piston engines.

if you do find any good information, by all means report it back here.

 

Thanks for that info Chris!!! I'll try those next and see how they do.

Thanks for the info guys,
STEPHEN

 

Yeah I ordered up a set of BR10EIX for use in my single turbo FD. I have 4x BUR9EQP in there now, and they are doing OK (no misfires and they are a nice medium brown color) but I want to try out something new to see how it works out.

Brian

 

Just incase you didn't know, you have to use a special spark plug socket to install these plugs. If you used any of the 'EV' series of plugs before you would know this. You can purchase the socket from Racing Beat or have one custom made for you. Normaly I would use a regular socket and have it turned down on a late.

crispeed
87 RX-7 TII
9.204@150.7mph
2600lbs
un-tubbed

 

There is a guy here on the forum that sells a socket for $20 shipped. I think he goes by Metalman. If you search the for sale section for socket you should find him. If not pm me and I'll check my super old pm's and get his exact name

STEPHEN

 

indexing is irrelevant on a rotary as the plugs have symmetrically arranged electrodes.

The idea in piston engines is to get all the plugs facing the one way with the electrode opening up to the flame front.

In a rotary the manner in which the flame promulgates from the tip will not really differ according to the direction it faces, as they look the same from each direction.

Only the EV/EGV series need to be gapped, the rest can't/shouldn't/aren't.

 

But as far as indexing goes would it be better for the plugs to face inward toward eachother and toward the center of the combustion area? Since the plugs are on the outer edges of the combustion area it would make sense to me that the "opening" in the gab should face the middle with the "bar" facing the bottom and top of the engine.

Does that make any sense at all.

I doubt any of this would matter to a street car but I'm just wondering. Hell since I'll be putting the plugs in I might as well do it in the best direction possible

STEPHEN