Unleaded in a 1986 944?
Discussion
My missus has been running an '82 924 for the last 6 years. Working on the principle that it is an alloy head with steel valve seats, we've been running it on one tank of four star to every three tanks of ordinary 95 octane unleaded. During this time it covered around 60,000 miles with no adverse affect (in fact, it actually felt marginally smoother on the unleaded).
However, last Tuesday she was driven into by a female OAP and the insurance company have written her 924 off. So she went out and bought herself a 1986 944! Now, totally different engine (obviously) but still has alloy head with steel seats. The book (and the little sticker inside the fuel filler flap) says leaded but it did on the 924 as well.
Anyone know if it can be run on unleaded or a mix as on the 924? Or what grade of steel is used for the valve seats. On initially looking, it appears that the ignition timing is set by the ECU and can't be manually altered, so I can't even retard it by a couple of degrees to prevent any possible preignition (although I didn't need to on the 924, that ran on standard ignition timing).
Thanks in advance
However, last Tuesday she was driven into by a female OAP and the insurance company have written her 924 off. So she went out and bought herself a 1986 944! Now, totally different engine (obviously) but still has alloy head with steel seats. The book (and the little sticker inside the fuel filler flap) says leaded but it did on the 924 as well.
Anyone know if it can be run on unleaded or a mix as on the 924? Or what grade of steel is used for the valve seats. On initially looking, it appears that the ignition timing is set by the ECU and can't be manually altered, so I can't even retard it by a couple of degrees to prevent any possible preignition (although I didn't need to on the 924, that ran on standard ignition timing).
Thanks in advance
Is it a 2.5? Mine says 98 ron on the filler cap so I use super (optimax or ultimate or whatever it's called).
Mark
PS. Top tip Iguana told me just *after* I tipped oil all over the engine, manifold, undertray etc... when you're changing the oil drain most of the oil out, then remove oil filler cap, then pierce the top of the filter and let that drain. If you do this you will apparently be able to drain most of the oil from the filter *before* removing it and your car won't smell of oil for weeks like mine does
>> Edited by dern on Thursday 5th February 21:35
Mark
PS. Top tip Iguana told me just *after* I tipped oil all over the engine, manifold, undertray etc... when you're changing the oil drain most of the oil out, then remove oil filler cap, then pierce the top of the filter and let that drain. If you do this you will apparently be able to drain most of the oil from the filter *before* removing it and your car won't smell of oil for weeks like mine does
>> Edited by dern on Thursday 5th February 21:35
This one also says 98 RON inside the filler flap. But so did the 924, that's why I asked the question.
The tip about the oil filter is one I've always used on anything where it doesn't hang downwards. It makes sense when you think about it.... but thinking about it isn't the sort of thing you normally do when doing something as simple as changing an oil filter!
The tip about the oil filter is one I've always used on anything where it doesn't hang downwards. It makes sense when you think about it.... but thinking about it isn't the sort of thing you normally do when doing something as simple as changing an oil filter!
Bit of a confusing year 1986, as early pre '2/85 944s should be run on 98 oct.
However 1985-87 engines still had the higher comprssion of 10.6:1 & the official Porsche line is that M44-05/06 engines of '86/87 should use 98oct unless they have had control unit (ECU ?) mods.
I'd use 98 or 97 super myself, I don't think any knock sensors on those engines either.
ps do you really mean you are useing genine 4star (I ask coz its flippin' hard to find & very pricey) or are you using that nasty LRP stuff? I wouldnt use LRP in my lawnmower! very bad reputation for killing engines.
However 1985-87 engines still had the higher comprssion of 10.6:1 & the official Porsche line is that M44-05/06 engines of '86/87 should use 98oct unless they have had control unit (ECU ?) mods.
I'd use 98 or 97 super myself, I don't think any knock sensors on those engines either.
ps do you really mean you are useing genine 4star (I ask coz its flippin' hard to find & very pricey) or are you using that nasty LRP stuff? I wouldnt use LRP in my lawnmower! very bad reputation for killing engines.
Ig, the car was registered 1/1/86 and is the oval dash model so it would be the later of the two versions (I think they changed in 9/85). When I say 4 star, I do mean LRP, there is one garage near me that still sells genuine leaded 4 star but I've never noticed a difference between that and Sainsburys LRP. There's also an airfield nearby where I can get 101 octane 5 star (that's all avgas is) if I decide I need it! Damn expensive mind.....
Like I said in the original post, the 924 never suffered any valve or seat wear in 60,000 miles of using 95 octane unleaded with every fourth tank being LRP. I would expect the valve seat inserts in the Porsche built 944 engine to be at least as good quality as the valve seats in the VW built 924 engine.
Maybe I'll suggest she carries on with the odd tankfull of LRP.
Like I said in the original post, the 924 never suffered any valve or seat wear in 60,000 miles of using 95 octane unleaded with every fourth tank being LRP. I would expect the valve seat inserts in the Porsche built 944 engine to be at least as good quality as the valve seats in the VW built 924 engine.
Maybe I'll suggest she carries on with the odd tankfull of LRP.
gilbertd said:I don't think there's any issue with the valve seats and you using unleaded, the only question is the octane rating. If you have an earlier engine you should use super and if you don't the 95 ron will be fine.
Maybe I'll suggest she carries on with the odd tankfull of LRP.
Mark
Dern is right its got nowt to do with valve seat recession* like some old MGB or somat, (*not an issue on any Porker or VAG product in the last 30 yrs as far as im aware) its pinking related why the 98ron is stipulated.
9M- you cheeky monkey, of course I have grass- well only a little bit as I've obvously tarmaced most of it
its just that unlike you Norfern Mooonkeys mines not hidden under Artic snow for 10 months of the year 
9M- you cheeky monkey, of course I have grass- well only a little bit as I've obvously tarmaced most of it
its just that unlike you Norfern Mooonkeys mines not hidden under Artic snow for 10 months of the year It isn't only old crap with cast iron heads that suffer valve seat wear, some early alloy headed cars had steel inserts that weren't hard enough to cope with unleaded. If possible pinking is the only thing, I'll just tell her to drive as I do and never let the rev counter drop below 3500!
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