Has anyone w/ GN1 heads, running more than 20 lbs boost, tried using AC R42T plugs. Buick GSCA says there is a possible detonation prevention advantage using the "T" instead of "TS" as they have shorter ground straps. I've always run Autolite 23's, but feel that the ACR42T plugs are worth trying. Thanks Brian
Tried AC R42T's w/ GN1'
- Thread starter Fuelie600
- Start date
Welcome!
By registering with us, you'll be able to discuss, share and private message with other members of our community.
87buick3825
Senior Member
- Joined
- Jan 8, 2004
- Messages
- 399
do you mean AC42LTS ???
AC R42T--- From the GS X-tra >>>"current considerations about spark plugs for your T-R may be changing. Some guys are now trying the AC 43T or the colder AC 42T spark plugs in their T-R's. As opposed to the AC 43TS or AC 42TS plugs, the "T" plug is not an extended tip design."
"Well, the idea was somewhat borrowed from the Mercruiser Division of Mercury Marine. They suggested a non-extended tip spark plug for their supercharged inboards to lesson the chance of detonation under a steady state, high load operation. The reason for this is that the ground strap electrode is shorter on a "T" plug as opposed to a "TS", so the heat path is correspondingly shorted and there is less chance for the strap to turn into a "glow plug" if the engine goes lean.
On a TS plug, or any plug for that matter, if the ground strap electrode glows red hot, then it can easily break off, especially if severe detonation also occurs. Then that little strap can wreak havoc in the engine or especially the turbocharger turbine as it courses its way out of the combustion chamber and through the exhaust"
"However, this little design change could also save your T-R engine or turbo, and you might never even know it. Furthermore, it's likely that guys running on the performance edge with higher boost might very likely see less detonation ( spark retard ) than they normally would experience. In these more extreme cases, the 42T plug ( for use with over 20 psi boost ) could actually help both performance and reliability."
"Well, the idea was somewhat borrowed from the Mercruiser Division of Mercury Marine. They suggested a non-extended tip spark plug for their supercharged inboards to lesson the chance of detonation under a steady state, high load operation. The reason for this is that the ground strap electrode is shorter on a "T" plug as opposed to a "TS", so the heat path is correspondingly shorted and there is less chance for the strap to turn into a "glow plug" if the engine goes lean.
On a TS plug, or any plug for that matter, if the ground strap electrode glows red hot, then it can easily break off, especially if severe detonation also occurs. Then that little strap can wreak havoc in the engine or especially the turbocharger turbine as it courses its way out of the combustion chamber and through the exhaust"
"However, this little design change could also save your T-R engine or turbo, and you might never even know it. Furthermore, it's likely that guys running on the performance edge with higher boost might very likely see less detonation ( spark retard ) than they normally would experience. In these more extreme cases, the 42T plug ( for use with over 20 psi boost ) could actually help both performance and reliability."
- Joined
- May 26, 2001
- Messages
- 9,208
The R42TS or R42T are both wrong for GN-1 Champion heads. These heads require a 3/4" reach plug which would be like the R43LTS like mentioned.
If you want a plug that will stand up under race-type conditions, use a race plug. Based upon personal experience, the AC plugs are junk under high boost.
Autolite, NGK and Denso all make race plugs that work great for high boost.
P.S. The Autolite 23 plug is NOT a long reach plug either.
If you want a plug that will stand up under race-type conditions, use a race plug. Based upon personal experience, the AC plugs are junk under high boost.
Autolite, NGK and Denso all make race plugs that work great for high boost.
P.S. The Autolite 23 plug is NOT a long reach plug either.
My bad! I correct my previous posts---- I use Autolite 103's NOT 23's. That shows what a constant lack of sleep will do for you. Anyhow, has anyone tried the AC 42T or 43T plugs with irons? Nick, what about AC plugs do you feel are crap? Do you, or anyone else know part #'s for a better GN1 plug than the Autolite 103. Thanks Brian
- Joined
- May 26, 2001
- Messages
- 9,208
In the NGK line I have used TR 5 [stock no. 2238] and TR 6 plugs. Not sure what their race plug is corresponding to these would be.
Had many of the AC plugs blow by the porcelin and some break the tip.
Had many of the AC plugs blow by the porcelin and some break the tip.
I've been using the autolite 103s because that's what was installed when the engine was built
which NGKs would be better, and do they make an iridium plug.
seems like these would work well. I tried the denso iridium in a "non boosted" LPE ZR1 (505 rwhp) and it tamed the idle a bit and pulls very cleanly to redline. helped with emissions too.
the denso iridum plugs cost a small fortune, but then, so did the zr1 !!!
which NGKs would be better, and do they make an iridium plug.
seems like these would work well. I tried the denso iridium in a "non boosted" LPE ZR1 (505 rwhp) and it tamed the idle a bit and pulls very cleanly to redline. helped with emissions too.
the denso iridum plugs cost a small fortune, but then, so did the zr1 !!!
The iridium and other "magic" plugs don't work well in engines with waste spark ignition. There are three cylinders that fire "backwards", and those funny tips aren't good at firing backwards. Go with the ACs, Autolites, or NGKs with the big center electrode and a standard side electrode, not a split tip. Or, you can convert to coil-on-plug, like the Vettes, and then use any plug you want. Somewhere on this board there is a discussion on how to use one coil per plug.
Originally posted by d0n_3d
well I guess I have freak plugs then??? I run the AC Delco CR43TS plugs gapped at .032" and I run almost 30 lbs of boost and there's not one single hint of detonation or missfire on c-16 OR even 93 and alky
i think the question was aimed at those with aluminum gn1'S
We have had allot of experience with plugs. what works and what does not. The standard plugs as mentioned above work fine up to a certain cylinder pressure. I would say that they would work good to 11.20 (1/4mi) range. anything quicker and they don't seem to hold up.
The iridium plugs work great beyond that and do not seem to be affected by the reverse spark problems. They are harder to gap. Detonation kills these plugs. they are fragile. We have tried several different heat ranges of the NGK iridium they last until you detonate the motor. After that they seem to misfire. Visually inspecting a set of plugs that misfires does not tell you anything as the plugs look prefect.
Lately we switched over to Denso iridium. I think the part # is IT20. These plugs are the best we have ever tried. We have not been able to kill a set yet. they are expensive though. $12 ea.
I was talking to the guys at the SEMA show last year that tune on these little high hp 4 cylinder motors. I think i was at the Dodge camp. They said that the Denso plugs are the only plugs that will fire at the high boost/ high rpm these motors run at. They also said that the Denso iridium was worth 40hp over any other plug including the NGK iridium. Weither or not this is true i don't know but they did not really have anything to gain by telling me a story. They guy tunning on the car (SRT4) said he was an old buick guy.
Lastly, there is a non tapered seat (washer seat) Autolite race plug with a short stubby fat ground strap electrode. They do not have an extended tip. These look like they would be the most durrable but we have not had enough run time on them to come to any conclusions with them yet. They are allot cheaper than the denso plugs so if they work they would be a good deal.
The iridium plugs work great beyond that and do not seem to be affected by the reverse spark problems. They are harder to gap. Detonation kills these plugs. they are fragile. We have tried several different heat ranges of the NGK iridium they last until you detonate the motor. After that they seem to misfire. Visually inspecting a set of plugs that misfires does not tell you anything as the plugs look prefect.
Lately we switched over to Denso iridium. I think the part # is IT20. These plugs are the best we have ever tried. We have not been able to kill a set yet. they are expensive though. $12 ea.
I was talking to the guys at the SEMA show last year that tune on these little high hp 4 cylinder motors. I think i was at the Dodge camp. They said that the Denso plugs are the only plugs that will fire at the high boost/ high rpm these motors run at. They also said that the Denso iridium was worth 40hp over any other plug including the NGK iridium. Weither or not this is true i don't know but they did not really have anything to gain by telling me a story. They guy tunning on the car (SRT4) said he was an old buick guy.
Lastly, there is a non tapered seat (washer seat) Autolite race plug with a short stubby fat ground strap electrode. They do not have an extended tip. These look like they would be the most durrable but we have not had enough run time on them to come to any conclusions with them yet. They are allot cheaper than the denso plugs so if they work they would be a good deal.
