[SeeTeaS-V]

With my mods im seeing a peak of about 12psi. I dont know the cars history, so i changed the plugs. They had br7ef gapped to like .24. I installed a fresh set of tr7ix gapped at .34, since my searches showed that being typical.

I also ran both br7ef and tr7ix plugs in my 427 camaro on 21.5psi and never had spark blow out.

i kinda feel like its down on power a tad after the plug change. Should i gap down or go back to a br7ef or both? Plug changes suck on this car.

PFA

 

[PGA2B]

I use TR7ix in mine gapped at .028

 

[07GTS]

always try to keep the widest gap u can without issues for the build u have, if its feeling worse just move gap in small amounts till its good again and keep there

 

[Karch]

always try to keep the widest gap u can without issues for the build u have, if its feeling worse just move gap in small amounts till its good again and keep there

Have you personally done this on a V?


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[07GTS]

Have you personally done this on a V?


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ive done a little on my PD boosted LS2, on ethanol with TR6 plugs standard gap was fine till bout 15psi then i went little smaller and the breakup feeling and data looked better, my understanding is that a wider gap has a better spark (as long as coils are up to it) so if it is operating fine with the standard wider gap then no real reason to go smaller unless there are noticeable gains from going smaller

 

[Karch]

Ok. I ask because on an LSA V, you are donating a lot of skin, literally, so changing plugs and creeping up on the ideal plug gap is purely sadistic.

I’ve had a bunch of mine mysteriously open up to 0.036” or so causing misfires under load. I need 0.026-0.028”.


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[07GTS]

Ok. I ask because on an LSA V, you are donating a lot of skin, literally, so changing plugs and creeping up on the ideal plug gap is purely sadistic.

I’ve had a bunch of mine mysteriously open up to 0.036” or so causing misfires under load. I need 0.026-0.028”.


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have u tried playing with the dwell time ? the stock coils can usually survive with a bit more in them which helps especially if ur on ethanol or meth with the denser fuel mix

 

[specialp]

Yes pulling all the plugs on these engines is not an easy task at all. They are deep down there. That said I run around .032 on a forged higher compression engine with 2.38 pulley.

 

[Rubber Duck]

ive done a little on my PD boosted LS2, on ethanol with TR6 plugs standard gap was fine till bout 15psi then i went little smaller and the breakup feeling and data looked better, my understanding is that a wider gap has a better spark (as long as coils are up to it) so if it is operating fine with the standard wider gap then no real reason to go smaller unless there are noticeable gains from going smaller

In general I agree with you..

I just want to add a few things if I may. . .
The plug gap which can be used, will also be dependent on the materials the plug is made of.
This is where iridium plugs 'Might' help.

Wider gaps are used to change the burn angle / time it takes to burn the mass charge.

Wider gaps, in any case, will also require more current be demanded from the ignition system.
More current tends to erode, wear, or even melt ground straps, and sometimes even electrodes.

Wider gaps tend to stress the entire ignition system though. . .

And sometimes, as one changes heat ranges, the gap also 'May' need to be changed.
And sometimes, as engine rpm is increased, one must begin to decrease the plug gap. . .

Cheers

 

[Lt1z]

Gap and heat range will depend on boost and power level. The more max effort builds will get into an 8 heat range (with NGK) and gaps under .030"

 

[jcmgt]

Gap and heat range will depend on boost and power level. The more max effort builds will get into an 8 heat range (with NGK) and gaps under .030"

Any experience with wider gap running IGN1A coils that support increased current/Dwell?

Something like this from panteraefi?
High Output Inductive Coil, Igniter included on Coil

1. Redline's High Output Coils deliver a powerful, long duration spark and are ideal for us in high-boost or high compression engines.
2. This coil is a specially designed inductive style, high energy coil IGBT (Insulated Gate Bipolar Transistor) referred to as a smart coil, as it is designed with the igniter on the coil. (TTL Transistor to Transistor Logic computer systems)
3. This coil has the potential of a Massive Spark Energy, (<250mJ, 8mS dwell @ 14 bolt) equal to and typical of the Capacitive Discharge Ignition (CDI) ignition systems, and delivers a very long spark duration that can only be achieved by using inductive coils.
4. This Massive Spark Energy <250mJ, and very high voltage, >81kV with incredibly long spark duration of <3.2mS is CRITICAL to maximizing power in high boost or high compression engines and when using the OE comuter or REDLINE's high performance TTL programmable fuel and ignition systems.
5. These coils are flawlessly being used on 3,000 hp nitrous engines without CDI. This is World Class performance!
6. The heavy duty construction is suited to operate in harsh environments and will handle substantial shock, vibration, and is weatherproof. This coil can be mounted virtually anywhere, including on the engine's valve cover. (i.e. GM LS1)

Specifications:

• Output Voltage: up to 81kV +/- 10%
• Output Energy: up to 250mJ +/- 7% (8mS dwell @ 14 volts)
• Peak Secondary Current: 100mA +/- 7%
• Arc Duration: 3.2mS +/- 10% @ 3.0mS dwell target
• Max Continuous Dwell: 9mS not to exceed 40% duty cycle
• Max Intermittent Dwell: 88% duty cycle for 9 sec max

 

[Rubber Duck]

Gap and heat range will depend on boost and power level. The more max effort builds will get into an 8 heat range (with NGK) and gaps under .030"

When I wrote my post yesterday, I intentionally left out boosted engines.
I thought you, or others would desire to cover this, rather then me.

Good Answer..
So let's expand on it. . .Or Why..lol

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

Because boost increases cylinder pressure, then the issue surrounding plug gap, versus the ability for the ignition system to ignite the mass charge held within the plugs gap (the kernel), if the gap is to large.

Your comments tend to agree with the requirement of decreasing
spark plug gap, as cylinder pressure is increased on NA engines I
have been involved with.

We have seen this when NA engines having ~15.5:1 static compression, along with a VE%, of about 118%, and where the peak engine rpm is 10,500.

Also, the peak torque on those engine is around 865 ft lbs.
Similar to a fully modified engine that you 'Might' be working with.

First it is good understand; the wider the plug gap, the larger the kernel will be ignited. If a larger kernel can be sustained, you will then have a larger 'Flame Front' propagating. A larger kernel will not tend to blow out later during the power cycle, if it can be fully ignited.

Conversely; if the larger kernel cannot be ignited, then one
must consider reducing the spark plug gap.

Or, consider installing a more robust ignition system.

At any rate, in my opinion; the larger gaps are highly
desirable, if they can be made to function. . . . .

Finally, you can push all of the voltage at this that you desire, but without sufficient current, the plug cannot be properly ignited. But then there is a downside to having to much current. . . .

On NHRA cars running Nitro, they use two (2) magnetos, with each magneto supplying a voltage of around 50kV, and each delivering +40 amps in order to fire 16-Plugs. It is not untypical for those cars to begin to 'Torch' the spark plugs ground straps, at or around the 1/8th mile mark.

-before the pass-

-after the pass-

 

[Blown376]

Something is wrong. I fully understood your post. 😄

 

[Rubber Duck]

Something is wrong. I fully understood your post. 😄

I must question if I am doing something wrong then..

 

[SeeTeaS-V]

You guys are getting into the nitty gritty of gap size on all sorts of applications... I came to the V forums because these cars have some age to them now, and I'm sure there are quite a few proven, repeatable recipes to make reliable power.
General consensus seems to be the LSA likes a tighter gap than what I am used to. (possibly since it seems to ingest more oil through the intake) That's all I need to know. It looks like the PO had a set of br7ef straight out of the box that seem to run well. I'm pretty sure I have a couple boxes of those at home, so I will go back to the tight gap, non projected tip, copper el cheapo plugs. Thanks

 

[Rubber Duck]

You guys are getting into the nitty gritty of gap size on all sorts of applications... I came to the V forums because these cars have some age to them now, and I'm sure there are quite a few proven, repeatable recipes to make reliable power.
General consensus seems to be the LSA likes a tighter gap than what I am used to. (possibly since it seems to ingest more oil through the intake) That's all I need to know. It looks like the PO had a set of br7ef straight out of the box that seem to run well. I'm pretty sure I have a couple boxes of those at home, so I will go back to the tight gap, non projected tip, copper el cheapo plugs. Thanks

You might desire to reconsider using cheap copper plugs with these engines…

 

[SeeTeaS-V]

You might desire to reconsider using cheap copper plugs with these engines…

I dont mean to come off as a dick, but you spent a good hour typing that long ass response with pics and info about top fuel dragsters ignition systems,completely avoiding my simple question. Then you toss out some random answer with zero reasoning behind it.

ive made almost 1200whp on those same plugs “on these engines”. Being vague here, LS platform.

im sure ill get bashed on because i offended the resident big dog, but your chest pounding is comical. Its ok, because Im not afraid to get dirty and try stuff.

Care to elaborate (in 200 words or less) why br7efs are no good?

 

[Lt1z]

You can use a BR7EF or B8EFS they just don’t last as long or idle as well for a given heat range as an iridium projected tip like a TR7IX or TR8IX.

I prefer iridium unless nitrous is in the mix

 

[Rubber Duck]

I dont mean to come off as a dick, but you spent a good hour typing that long ass response with pics and info about top fuel dragsters ignition systems,completely avoiding my simple question. Then you toss out some random answer with zero reasoning behind it.

ive made almost 1200whp on those same plugs “on these engines”. Being vague here, LS platform.

im sure ill get bashed on because i offended the resident big dog, but your chest pounding is comical. Its ok, because Im not afraid to get dirty and try stuff.

Care to elaborate (in 200 words or less) why br7efs are no good?

First there is a better plug, it is called Iridium.

Second, Iridium plugs can manage at least 2-Times the heat,
that most simple copper plugs can.

Third, a well designed Iridium plug, offers as much as 25%
more area, where the flame kernel is formed.

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

You wrote:
"im sure ill get bashed on because i offended the resident big dog, but your chest pounding is comical. Its ok, because Im not afraid to get dirty and try stuff."

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

My friend; this is a technical forum. With my first post, I simply posted a technical post!
You seem to have taken something personal with my second post, which was not my intent.

I made that second post upstairs, on my Apple ipad. I don't like
using it, but I did it in an effort to make you hesitate, and think. . .

I did this to alert you that I thought you might want to reconsider the 'Cheap Plugs'.

There was nothing personal contained in my post, so I don't know why it irritated you?
Just a simple; think about this post. . . .

Now, you move ahead to use whatever plugs you desire to, no hard feelings. . .

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

Let's move on to what your engine is, and how you are making 1200 rwHP?
Is this a street car?

Finally, why have you made the decision to tighten up the plug gap?

Cheers

 

[SeeTeaS-V]

Turns out, I did sound like a dick. Sorry. Yea, it's a technical forum for the CTS V... I do know the general rule of thumb is to keep the gap open unless you're getting blow out. What I don't know, are the specific intricacies of the LSA. As I mentioned before I'm sure there are proven recipes for X amount of power on this platform. I was just hoping to keep from doing 6 plug changes to find out what most people here already know.

And I agree with you, on my LS3 based 427, I've tried both the tr7ix and br7ef. The Iridium's idle much better, but that was the only up side I found. I can't speak to longevity as I preferred to check/change more often. I found you could throw more timing at the copper plugs, plus the benefits of the non-projected tip, and the cost of the plugs. Since idle quality wasn't really a concern, it was a no brainer. BR7.

Old setup was 427 10.3:1, M311 heads TMS centri cam, centri blower, E85.

Now with the V, I do care about idle quality, which is why I installed TR7ix. But that didn't seem to improve, although the tune needs some work. I found my catch can was almost full, and when I popped the Lid, I saw quite a bit of oil on the brick and intake. I'm guessing this could be one of few reasons why it wants a smaller (than ls3) gap. I'll try .30.