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Compression Ratio


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#1 600Z

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Posted 21 November 2016 - 12:48 PM

Hi guys,

Just a quick one with a closed chamber head E88 EFI head what sort of compression ratio would I get away with before running into detonation issues? I know there are many other factors involved with the tuning etc.

Years ago I ran 10:1 with an opened up chamber head and that was fine but I'm reading there are some who go higher.

#2 Lurch ™

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Posted 21 November 2016 - 01:52 PM

 I know there are many other factors involved with the tuning etc.

 

You've just answered your own question, Jason.


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#3 600Z

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Posted 21 November 2016 - 02:41 PM

Lol yes Locky I know but just trying to get a bit of an idea of what static compression to run, probably stick to 10:1 but just getting an idea what people are getting away with.

The engine is just a street engine for my wife's car and I'm looking at the following specs, though in time I'll probably do the similar to our other 260 as I have another one of the heads and set of 45 dellorto's.

F54 block 87mm bore
E88 EFI with port and chamber work but not over the top
72 - 74 deg cam
280zx electronic distributor re curved and no vacuum advance
Triple 45 dellorto's with 34mm Venturi's
Extractors 3/2/1 with 1 5/8" primaries 2 1/4" exhaust.
Lighter flywheel but not too light.

Justin

#4 Lurch ™

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Posted 21 November 2016 - 06:44 PM

Would have been helpful if you'd posted that info in the first place! :P

You'll be fine up to 10.8:1 with 32 - 34deg timing on PULP98, with those spces Jason.



#5 600Z

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Posted 21 November 2016 - 09:18 PM

Lol yes your right Locky I should have I know.

Thanks for that, I didn't think I'd be able to go that high but fuels are better I guess these days. The distributor I have built and it this stage only by measurement has now 11deg of advance so as you know 22 on the crank. My thoughts are to start at 10 and go to 32 but I can play with that once done.

But that's good I won't have to take too much out of the chambers at all, just unshroud the valves and a polish and keep them small.

Thanks again for that.




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