Back in the day when they took lead out of gas there was a lot of concern that without the cushioning effect the lead had on the valve face there would be bent and broken valves. Since my car fits those criteria and will be driving soon what if any concerns should I be aware of?? Fairly technical but Thanks for any help that might save me a damaged engine. Best to Ya

All 914 engines use hardened valve seats so no problem running unleaded.

I don’t know why but my 1.8 seems to run a bit smoother with a half-dose of lead substitute additive each fillup.
Use premium, too, as don’t drive mega miles so not a big cost issue.

As I recall lead formerly in pump gas was also a lubricant that helped the valve stem/guide, but the engineers figured it out. I haven't heard of many failures due to a lack of lubrication.

Do you know how far back that applies I'm referring to a 1970 2.o ltr six

interesting question. the porsche engines might be different.

i have a mate here who runs an aus delivery 76 911S.
same as europe - leaded fuel high compression engine.
he feeds it lead substitute in the gas.

From what I have read, all Porsche engines since at least the 60s had hardened seats so will do fine with unleaded gas - at least from what I've been able to find online. I'm sure someone else can verify or refute that. VW-Porsche magazine had an article where they tested the hardness of Type IV valve seats. They might have tested others but it was a long time ago and I was only interested in Type IV at the time. The upshot was that the factory seats were plenty hard to run unleaded without problems so I'm very confident we don't need lead additives in our 4 bangers. Also, if valve seats have been replace on any engine as part of a rebuild since the 70s, they will be hardened seats, so no need to worry about lead additives.

This is a topic where facts get buried under opinion which always attracts me to learn more. Here's what I've gleaned:

Lead was originally added as an octane booster. The lubrication properties were a side benefit. The most important was that a layer of soft lead would build up on the valve seats and cushion the impact of valves as they closed. Some manufacturers took advantage of this by using softer seats. As for other lubrication properties, modern fuels also have them, but with non-lead additives. Finally, what usually gets overlooked is the corrosive properties of lead in an engine. It seems lead may have done more damage to engines than the benefits.

We also shouldn't confuse the effects of lead as a lubricant and its effects as an octane booster. The latter is a whole other topic where anecdote and opinion seems to swamp fact.

BTW, I've also read that all aluminum heads used hardened seats but I don't know if that is accurate. Anyone know?

True. I’m sure there is some exception somewhere. It would make little sense to go to the expense of using aluminum as a head material and then to try to thrift the valve seats with cast iron seats.

Another way to look at this: if VW was using steel seats (and they were) in their engines - why would Porsche cheap out and use cast iron? No way that was happening.

The whole topic of valve recession back in the day was largely spun up based on concern for turn of the century - 1970s domestic iron with cast iron heads and/or the even more archaic side valve engines that had the valve seats cut in a cast iron block.

Two more thoughts, one I faintly remember sodium filled valves as part of the solution second since modern day premium fuels don't really refer to octane rating but more so to knock retardant additives is there really a difference between grades as far as power output. Thanks for all the responses its greatly appreciated.

The greatest harm to the engine is from fire. The ethanol eats the older hoses and leaks. I think the engines can benefit from the additives, and I'm sure a case could be made for longevity, but hard to actually quantify.

Sodium valves have nothing to do with valve recession solution.

Sodium valves were used to try to prevent exhaust valves from burning. Sodium valves are still in use today on high output engines as a way to remove heat from the valve head, transferring it down the vale stem, into the valve guide and ultimately the head.

Likewise octane rating has nothing to do with power output on its own. Octane rating just allows for higher compression ratios (more power) and more timing advance.

You will not get more power running 93 octane in a 914 than you will get on 87 octane. Where octane rating comes into play is the ability to run more timing advance without getting Detonation that destroys engines fast! On a modern car timing is altered automatically in real time via the Knock Detection sensor(s). Timing try’s to run as advanced as the timing map will allow, if detonation is detected, timing is retarded until it stops.

On a 914 you can get more power (in some situations) by advancing timing. The problem is it is set there and can’t be adjusted in real time. If you start getting detonation and ignore it, piston melting, piston holes, etc come next.

Our engines don't really benefit from the higher octane as we are not generally running a high compression.

Here's a rule of thumb Octane/compression chart. FWIW, I'm theoretically running 8.2:1 compression as calculated by deck height (haven't measured directly) and it run fine on regular gas. I do run at high altitude though which requires less octane. I might have to bump to mid-grade if I ever drive down out of the mountains.

And just to complicate more, ethanol blend has more oxygen than pure gasoline so runs a little leaner.

Click to view attachment

yes. that does make sense.

i think my mate down here was/is really using an octane boost additive that he has fallen into the habit of continueing to use since he has boxes of the stuff. he runs quite a few old 60s and 70s aussie fords.

unleaded until the late 90s early 2000s was not super high octane here. think it went up to 95. then we started getting 98 - opened the gates on more new import european models of cars being sold here. the 70s porsche 6 had higher compression than the VW 4 bangers - at least down here. so whatever people were doing it was just to boost the octane to make them run a bit sweeter during the 90s.

i'm sure when it came to the USA market that anything porsche or vw were doing was set up for unleaded from late 60s. it had to be. everyone knew unleaded was on the way from 1969 on. there was a timetable to get to 1974 set in 1969.

as an aside, apart from removing lead as a dangerous material from fuel, i believe the real reason was agreement among manufacturers and the EPA that catalytic converters were the technology to clean emissions to the standards the EPA wanted achieve. to use cats the fuel had to be lead free. lead kills a cat.

So this is a very interesting topic....would putting lead additive into a '73 2.0 gas tank help with anything? Improve anything? Add some extra cushion of comfort for anything?
Thank you all very much!
gg

the 2.0 L engines all have/had the lower compression ratio in stock form suitable for unleaded - what was really of consequence was that initially unleaded had significantly lower octane level than leaded premium fuels in that era.

the 2.0 had a 7.6:1 compression ration.

the EA 1.7 for california in 73 had a 7.3:1 c r.
the EC 1.8s all had 7.3:1 c r.

all of these engines were 100% designed to run on unleaded fuel.

i am sure the earlier 1.7s despite a higher c r of 8.2:1 run just nice on today's higher octane fuels. but back then it might have been an issue. but as suggested above by folks who know what they are talking about, its not an issue of valve "lubrication" for VW and porsche engnies. it would have just been octane and higher compression issues.

i've never run anything but straight from the pump unleaded in my 1.8 for 30+ years.

And don't forget GB engines (euro 2.0) had 8.0:1

AN engine (euro 1.8) more highly strung (if you can call a VW engine that) - 8.6:1 - 98RON top shelf drinking habit. the dean martin of VW engines.

no surprise it was almost as powerful as last of the USA 2.0L.

no low octane unleaded for those babies.

@Van B wants some of those AN pistons. i know what he is up to.
a sleeper 1.8 disguised in L jet clothing.

there is a bit of a mystery in relation to those AN engines that we have been trying to get to the bottom of.

there is not much difference between the parts for the 1.8 EC (usa) and the 1.8 AN (ROW).
just the pistons.
and the heads.
the heads have a different part #.
the valves and the valve guides are listed as same part for both.
camshaft = same part.
this is using the PET manual euro version and also comparing to PET usa version.

so.......i dunno what is in the heads of the 1.8 that makes them list it as a separate part #? but there must have been something????

As @Superhawk996 described, you can rest assured that if you have aluminum heads, you’ll be fine with unleaded. But, until anti-knock sensors came around you did have to pay attention to the minimum octane rating. In the US we use the (RON+MON)/2 with motor octane being a lower number than research octane, you won’t see our fuel numbers matching the RON only number, but the measure I’ve always used is to add 5 to the number at the pump to know if it’s high enough octane for you engine’s listing in RON. For example, 91 RON means you can run 87 octane from a US pump.

@wonkipop I think the heads may have been different due to runner configuration for the carbs.

@wonkipop I think the heads may have been different due to runner configuration for the carbs.
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i thought that too ------- to start with.
but i fully investigated it.

there was a small inlet casting that bolted up to the same studs and casting area that the fuel injector/air inlet manifolds bolted up to. the inlet casting transitioned the single barrel carb on each side into two inlet tracts into the head.

so i don't think it was that.

Note that our engines do not follow this chart very well. The combustion chamber shape, mixture and timing control, and cooling that we have generally means we suffer detonation earlier than more modern engines do.

In stock form, the 2.0 and 1.8 engines take regular-grade fuel. The 1.7 engines (except for the low-compression California-only 73 1.7) take super-grade. The European-spec 2.0 (8.0:1 compression) takes mid-grade, and the European-spec 1.8 (8.5:1) takes super-grade.

--DD