Leaded or Unleaded?

elflover · Post by **elflover** » Sun Feb 18, 2007 1:46 am

I´m not quite sure if I can use Leaded or Unleaded fuel for my 2.2T from 1971. Any suggestion please?

Jim Richards · Post by **Jim Richards** » Sun Feb 18, 2007 2:22 am

My 2.7RS spec engine runs on unleaded.

Viv_Surby · Post by **Viv_Surby** » Sun Feb 18, 2007 10:26 am

The Porsche aircooled engines were designed to run on low octane unleaded fuel sold in the US at the time. Unleaded therefore is fine as indeed is 'normal' unleaded - higher octane fuels 'super' fuels in fact are too high without adjusting timing.

I'm sure a more teccie bod here can post more detail.

You'll find everyone here uses unleaded

jamie · Post by **jamie** » Thu Feb 22, 2007 12:37 am

Eh?

Is it better to run 95 over 97? I tend to use 97, although I've timed the car for it. I thought lower octane fuel burns valve seats on older motors?

willbrown · Post by **willbrown** » Mon Feb 26, 2007 10:49 pm

Pretty sure Viv is right - definitely for MFI cars (see: http://www.ddk-online.com/phpBB2/viewto ... ght=#61889). Try consulting the factory manual for carbs...

hot66 · Post by **hot66** » Tue Feb 27, 2007 8:06 am

Viv is correct for 2.4 litre cars.

Jim Richards · Post by **Jim Richards** » Tue Feb 27, 2007 4:25 pm

bjmullan · Post by **bjmullan** » Tue Feb 27, 2007 4:33 pm

I think Viv is right for all early motors and that also includes VW engines as well. If you have a old British engine then that is a different matter.

210bhp · Post by **210bhp** » Tue Feb 27, 2007 5:20 pm

The 67S motor runs at a higher comp. ratio than the MFI (I think about 9.8:1 as against about 8.5:1) and benefits from a higher octane rating so I run the S on optimax and the RS on standard unleaded and they both seem to work fine with that.

Regards
Mike