Date: Mon, 30 Apr 2001 19:45:12 +0100 From: John Griffin <johnnopsamfinphoto.u-net.com> Subject: Re: Bosch 4-Plus Plugs: Good Idea or Bad?
in article 3AEB2AE1.F0076512nopsamhlink.net, Ken Washington at kenwashinopsamhlink.net wrote on 4/28/01 6:46 PM: > I never like to disagree, but in this case you may be wrong. The reason > I tried the Bosch Platinum + 4 plugs in my 87 9000S, is because my > Saabtech friend ran a set in his 87 9000T. > The only turbo models that really depend on the NGK plugs are the > DI-equipped cars. Apparently Saab designed that system to work with that > particular plug, but in non-DI equipped cars there really is no problem. > I ran the Bosch Platinum single electrode plugs in my 83 900T, 87 900S > and 87 9000S without a problem. The key is using the correct temp range > and gap. > On my 900T I ran a gap of .026. On my 87 900S and 87 9000S I ran a gap > of .028. Now, I don't have to worry about a gap and I love it. > > Ken Washington > 87 9000S > 87 900S > 83 900T > > Here in the UK every Saab specialist I have ever come across would say the contrary but I will limit my response to my personal experience. I have owned 5 900 turbo's (presently 2 T16's) and have tried just about every make of plug going including standard Bosch ones. They have all caused misfire - mostly when the boost reaches the upper limit - very frightening! I have run NGK's for the last 3 years with no problems and that includes a 91 with an uprated 185 bhp APC system. Now I have to admit I have never tried the expensive Bosch Platinum - 4 as they are not recommended by Bosch or Saab for use in a T16 - the Saab 900 owners manual for 1991 only recommends NGK plugs for the fully blown 16v engine - only for the NA models does it give a Bosch alternative. Now I must add that most of the problems came with the T16 engined cars but as they have a higher compression ratio and a higher maximum boost this is not to be unexpected. I can see no problem in these plugs working in your vehicles as they are not T16's and simply do not put the same stresses on the ignition systems as the T16 - which for a turbo engine has a very high compression ratio . You mention you were recommended these plugs by a 9000T owner - did you use identical plugs - they should have a different temp rating! I think I am right in saying the US spec engine has a lower output by some 15bhp (it did in the 900) which would be less of a strain on the plug. You observe that the correct gap is essential - I wholeheartedly agree - but how do you gap a 4 electrode plug? I would have to have a very good reason to change - perhaps the recommendation from an owner of a car with a T16 engine who has run them successfully - no one I know with a T16 will touch anything other than NGK
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