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#11 |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 898
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Keep in mind that virtually all plug recommendations in catalogs, regardless of manufacturer are, IMO, too hot.
When the 1G LT5 was in final validation back in the late 80s, GM and Lotus specified the FR1LS spark plug, which was in the ACDelco #1 heat range. That offered best performance in all normal street driving duty cycles. Right as the car was reaching dealers, because of concerns about "pre-delivery plug fouling" and its effects on customer satisfaction, the spark plug spec was changed to the FR2LS, which was the one range hotter #2 heat range. The only reason GM did that was to avoid warranty problems with any pre-delivery spark plug fouling which might occur and addressed some customer complaints of new car with fouled plugs. When ACD started publishing spark plug data, it listed the FR2LS and all the other plug makers followed that lead, i.e." NGK lists their 5 heat range, Denso lists its 16 heat range and so on and so forth. No one in the C4 ZR-1 community needs to be concerned with pre-delivery fouling and use of the 2 heat range plug, unless their ZR-1s are never driven normally and are subjected to duty cycles such as frequent starts-without-warm-up, trailered car-show use, short trip street driving only use with no high-rpm or high load use. Anyone who drives their ZR-1 normally...ie: seldom or never any starts without-warm-up, should go to a colder plug. Such as: ACD #1 heat range NGK 6 or 7 Denso 20 or 22. The reason you want a somewhat colder plug is that hot plugs make the engine more prone to detonation under high-rpm/high-load operation. For the last 15 years I owned Barney, my 500-hp '95, I used the Denso IT-22 exclusively. It worked very well on the street and in mild racing applications. Before that I used the NGK 7 heat range. The NGK TR5IX is too hot a plug unless the car is a show car and never is driven normally. You need at least a TR6.
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 Last edited by Hib Halverson; 01-23-2017 at 06:14 PM. |
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#12 | |
![]() Join Date: Mar 2014
Location: Warrington PA
Posts: 1,914
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I now have 68,000 + on the 94, the plugs were changed by a PO @55,000 miles. The plugs that are in there are AC 41-963 Thanks for the info.....appreciated.
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Tom 1994 ZR-1 #009 "captured test fleet car" 1974 LS4 454 Vert 1974 L-82 355 Vert. 1982 L83 CFI...now a retired "dd"....Sold WAZOO Member |
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#13 |
![]() Join Date: Feb 2011
Location: San Marcos CA
Posts: 1,786
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Factory heat range is usually ideal for the low speed emissions testing, but maybe I will try an alternative at one range cooler someday because you can definitely get some pinging on CA 91 octane gas in the summer.
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#14 | |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 898
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 |
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#15 | |
![]() Join Date: Mar 2014
Location: Warrington PA
Posts: 1,914
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Thx, appreciated.....
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Tom 1994 ZR-1 #009 "captured test fleet car" 1974 LS4 454 Vert 1974 L-82 355 Vert. 1982 L83 CFI...now a retired "dd"....Sold WAZOO Member |
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#16 | |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 898
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When I had my 95, because I was at sea level, the only time I never saw KR at WOT was when it was really cold out. Once it warmed up outside I'd start to see KR. If it was a hot day I'd get a consistent 5-7 deg. spark retard. What the colder plug will do is keep the spark plug from making the knock situation worse, if the detonation incident occurs under wide open throttle/high-load conditions.
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 Last edited by Hib Halverson; 01-25-2017 at 11:39 PM. |
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#17 |
![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,466
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For what it's worth...
41-602s in Pete's Green Monster https://www.youtube.com/watch?v=SFNFOhGGlR4 41-602s after one year in my 500+ LT5, gapped at .035 ![]() |
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#18 | |
Join Date: Feb 2016
Location: Carterville Illinois
Posts: 854
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For us un-mechanical folks, what am I looking at? Spark plugs obviously, but are these good looking plugs for a year worth of use? Were they fouled or anything, and what does gapping do? I'm wanting to change my plugs, would they need gapped or is that for modified engines? |
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#19 |
Join Date: Jan 2017
Location: US
Posts: 233
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#20 | |
![]() Join Date: Nov 2016
Location: Norway
Posts: 397
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https://www.autohausaz.com/html/spar...lug-wires.html
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- '90 ZR-1 |
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