[Diy_efi] Knock retard and Race gas

[Charles Woock]

Check out this site and article.  Scroll to the bottom and open the article 
on "ignition and combustion".  This will explain the answer to your 
question.  http://www.sdsefi.com/tech.html  Be sure to check out the other 
articles!

Charles


----- Original Message ----- 
From: "James Seabolt" <turbofiat at hotpop.com>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, July 26, 2006 9:28 AM
Subject: Re: [Diy_efi] Knock retard and Race gas


> At 02:13 PM 7/11/2006, you wrote:
>>Isn't there someone on this BB that has a masters degree in Internal 
>>combustion??? if not Others might know. On a local club board we are 
>>discussing higher octane race fuel ( 100/103) vs standard 98/93 pump fuel 
>>and knock. We all know how well it will reduce some knock (KR) that our 
>>3800 series 2 Supercharged ( pontiac grand prix 97-03) cars from 
>>compression ( supercharger) of the air mixutre ( which heats it)... It wil 
>>reduce the knock via more complete combustion and reducing the KR we get 
>>form the supercharger... the question comes up
>>
>>   If a car has 0 knock ( detonation) and you put hight octane gas in the 
>> tank for race purposes, does it give you  an advantage, or are you 
>> waisting your money??? Personally I think that even if you dont get the 
>> advantage of reduced knock your still getting a better combustion and 
>> therefore a more power from the cylinder... Yes/NO
>
>
> I had no luck running a knock sensor on my 1980 Fiat Spider. I ended up 
> taking it off and going with a system that retards the timing as soon as 
> the turbo kicks in. This car has a C/R of 8:1 and before I put the turbo 
> on, the sensor said it knocks at high RPMs. There is no way this car 
> should knock without a turbo.
>
> Interesting I put some 114 octane gas in it and the meter showed less 
> knock. This was before the turbo!
>
> Someone told me if an engine has allot of piston slap will confuse a knock 
> sensor and I think that was what was happening.
>
> I replaced the head gasket a couple of years ago but the rebuilt engine 
> block has about 60K to 70K miles on it. So whatever is going on in my 
> engine must not be causing any problems.
>
> I replaced the head gasket because Fiat 124 Spiders have really bad 
> designed cooling systems. The radiator is lower than the cylinder head for 
> one thing and if the radiator cap is not functioning properly the fan will 
> kick on at a higher temperature than 190F. My fan was kicking on at 235F!
>
> I've been meaning to mount a fan blade from a Lada Niva and bolt it 
> directly to the waterpump to get rid of that troublesome electric fan. I 
> just haven't done it yet because my fan spacer I made did not turn out too 
> well. And I got other projects I've been working on.
>
> The head gasket didn't blow but was leaking oil in all the usual places so 
> I thought I'd replace it before it got any worse.
>
> 60K is probably the life of a head gasket on an old Fiat twin cam.
>
>
>
>
>
> James Seabolt
> Tennessee, United States
> Homepage --->>> http://users.chartertn.net/jseabolt/
>
> 2003 Subaru Baja
> 1980 FIAT 2000 "turbo" Spider
> 1968 Ford Fairlane 500 (Not a Ford Galaxie!!)
> 1987 Yugo GV 1500cc also turbocharged
> 1979 Brava four door, 5 speed
> 1980 Brava four door, automatic, power steering
>
>
>
>
>
>
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