Leaded or unleaded - That's the question, Need advice on which type of fuel to use.. Options

[reineg]

Hi there, Laymen and Experts alike!

I have recently acquired a 914/4-70 with a newly built engine. Up to 2.2litre and some extra horses to boot. But now to the question:
The car has got new cylinders and pistons from Pelican Parts, but I do not know much more about the engine. So do you guys (and gals) reckon it would be safer to use modern fuel and add lead, or shall I just go for modern fuel and not add lead?

What is most detrimental to the engine; to add lead to an engine that doesn't need it, or not to add lead to an engine that requires it?

Appreciate any and all thoughts on this..

[bkrantz]

But the challenge the OP has with a modified 2.2 liter four is what compression ratio he has. Lead additive, no, but he might need to use higher octane to run that motor hard.

[wonkipop]

But the challenge the OP has with a modified 2.2 liter four is what compression ratio he has. Lead additive, no, but he might need to use higher octane to run that motor hard.

very good point.

probably needs highest octane unleaded available.
be 98 RON in aus.
i think you guys in USA rate your octane slightly lower.

i can run my 1.8 on 91 RON here which is i think equal to 89RON usa.
i sometimes run a tank of 95 RON through it.
i don't notice any difference in performance. ha. (IMG:style_emoticons/default/biggrin.gif)
not at its low CR. (IMG:style_emoticons/default/biggrin.gif)
but i tend to do it for a highway run. figure its kinder on the engine then.
but be buggered if i ever detect any real difference.
maybe marginal fuel economy but its pretty slim difference.

i know the factory 2.0 in the USA and i think ROW ran on 95 RON.
but the european 1.8 with twin carb needed 98 RON and had that sticker.
it ran a higher compression ratio than even the 2.0 D jets.

i'd be running the OP's car on the highest octane i could get.

[Dave_Darling]

probably needs highest octane unleaded available.
be 98 RON in aus.
i think you guys in USA rate your octane slightly lower.

We use AKI, "Anti Knock Index". Also labeled "(R+M)/2". It is the average of the RON and MON octane numbers for the batch of fuel, and the number is about 4-5 points lower for the same fuel than the RON number.

Your 98 RON is about 93-94 AKI.

--DD

[wonkipop]

probably needs highest octane unleaded available.
be 98 RON in aus.
i think you guys in USA rate your octane slightly lower.

We use AKI, "Anti Knock Index". Also labeled "(R+M)/2". It is the average of the RON and MON octane numbers for the batch of fuel, and the number is about 4-5 points lower for the same fuel than the RON number.

Your 98 RON is about 93-94 AKI.

--DD

yeah that sounds right.

three grades of fuel are sold here.
91 RON 95 RON 98 RON.
all of it accords with the grade of fuel on my cars filler stickers.
mine are all euro manufactured cars.
the RS clio takes the 98. which is getting pretty xxxy in price now!!!!
the 2006 audi A3 1.8 turbo takes the 95.
the 914 takes the 91. which accords with the 91ROZ.RON sticker in the frunk.

what was the case in the USA back in the 70s.
was the fuel rated by MON back then.
i can't remember the late 80s anymore when i used to live in chicago.
what the fuel was marked as. too long ago. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)