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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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 Posted: Tue Nov 20, 2007 12:43 am Post subject: Spark plugs and water injection for 931 |
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Hi there - I have a 1980 931 with some of the usual enhancements (bigger exhaust, water injection, MSD Digital 6 ignition for the rev limiter).
I want cooler plugs for this car. One set I'm looking at is the NGK Iridium BPR 8 EIX. Has anyone had experience with these plugs? Or is there another set of COOL plugs that's best?
Also, what about plug gap? Is it smart to raise the gap to 0.033 in. or so?
Finally, I'm releasing about 175 ml/min of methanol/water (50:50 mix) into the airstream before the throttle at 4 PSI. Is this too much?
Thanks for any leads you can give!
PS I got some leads from the South (Aussie/NZ) but I can't get those plugs here, but thanks. |
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Lizard
Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada
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| Posted: Tue Nov 20, 2007 1:40 am Post subject: |
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on an engine with boost, ALWAYS use copper plugs.
and you shouldnt need water/methanol injection untill about 10PSI.
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3 928s, |
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Tue Nov 20, 2007 1:57 am Post subject: |
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Hi Lizard, and Thanks! Do you know of an NGK COOL plug with copper? Like an '8' or '9'? I have detonation when the car first spools up and begins to take on load - at low/initial boost onset. I'm thinking a hot plug might be causing this detonation.
The head was reconditioned and as is often true with reconditioned heads, it is possible the head was shaved - higher compression. This too might be causing detonation.
The 4 PSI switch is what I'm currently working with from Snow Performance but I'll keep my eye out for another switch for higher onset. |
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Cedric
Joined: 27 Aug 2004
Posts: 2809
Location: Sweden
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Tue Nov 20, 2007 6:54 am Post subject: |
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| That'll work. Thanks. |
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Tue Nov 20, 2007 7:35 am Post subject: Re: Spark plugs and water injection for 931 |
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| tuurbo wrote: | | I want cooler plugs for this car. One set I'm looking at is the NGK Iridium BPR 8 EIX. Has anyone had experience with these plugs? Or is there another set of COOL plugs that's best? |
From this thread:
| Khal wrote: | The plugs are near-new. Couldn't have more than 5000km's on them. They're NGK BR8EIX plugs. Iridium jobbies.
| Tigger937 wrote: | | That plug is 1 heat range colder than what NGK recommends for your car. I've heard of this being done before since the turbos are known to run hotter. This may be related to your problem. The plug may not be getting hot enough to burn off the condensation buildup in your engine. You might try switching to a hotter plug, perhaps the BPR7EIX recommended by NGK. |
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Never had any problems with plugs themselves.
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'80 924 Turbo |
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Cone_Eater
Joined: 29 Jul 2007
Posts: 126
Location: Marshfield, MO
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| Posted: Sun Dec 09, 2007 5:45 pm Post subject: |
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For the colder range on an NGK plug go up one number. Just go into an oreilly store and have them look up the stock plug and tell them to go one step colder. We have listings for the heat ranges of NGK plugs. The 9 is a colder plug than the 8. The pre number of an NGK stands for the type and the actual number is the heat.
_________________
1988 924S: Koni fully adjustables, Short shift kit, head work, exhaust, K&N, Jacobs ignition, Larger Injectors, Performance Chip, 928 wheels with cooper Zeon tires, Momo interior, Etc.....
If its fast enough to go... its fast enough to blow. |
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endwrench
Joined: 07 Dec 2002
Posts: 1631
Location: Victor, Montana
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| Posted: Mon Dec 10, 2007 7:26 am Post subject: |
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| tuurbo wrote: | | Hi Lizard, and Thanks! Do you know of an NGK COOL plug with copper? Like an '8' or '9'? I have detonation when the car first spools up and begins to take on load - at low/initial boost onset. I'm thinking a hot plug might be causing this detonation.. |
This sounds more like a timing or compression problem rather than a hot plug problem. You usually don't get pre-ignition problems (wich is what a hot plug generally causes, not detonation) from a hot plug until it has been superheated by hard running. Not always, ofcoarse.
| tuurbo wrote: | | The 4 PSI switch is what I'm currently working with from Snow Performance but I'll keep my eye out for another switch for higher onset. |
This site has a part listed for an adjustable switch wich might work for you:
http://www.turbomirage.com/water3.html
and this site has a calculator for determining how much water you need to inject. I can't actually make heads or tails of it but you might.
http://www.rbracing-rsr.com/waterinjection.html
Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!.... |
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