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Why can a stock 1.8 redline at 5800 in a 914 and the same engine in a 75 vw van shouldn't be reliably driven over 42-4500? Are there different internals? Is it the weight of the vehicle? My 1.8 in my 914 seems much more happy to be reved up above 4500 than the exact same motor in my parents westfalia van, but they're the same motor right? Is it just the gearing in the 914 is different and thus easier to accept higher revs, plus lighter vehicle?

They are the same enough for repair and maintenance purposes. Don't know if you have noticed but a 914 has very different intake and exhaust system and typically specc'ed different from the factory;

http://www.tunacan.net/t4/reference/case.htm

The two main things on a VW that determine the red line are the rods (bolts) and the valve springs (or the weight of all the valve train parts in relation to the spring pressures). There is no reason at all if these are the same, that it should not use the same red-line.

However,. . . If you drive that same motor that's in your 914, in a bus and still try and drive it like it's still in the 914, it won't last very long. You've nearly doubled the load placed on that motor and you will over heat it in a hurry in a bus. It must be driven like as bus if it's in a bus. These motors last forever in a 914. I personally have 300K+ on my 1975 Porsche 914 with a 1.8L and it's all documented miles. Yeah, it's a little down on power, but is runs perfect, doesn't smoke and fires-off on the first crank every time. I have yet to see a 1.7, 1.8 or 2.0L motor in a bus last much past 140-160K (normally around 80-100K at best. It's all due to the load placed on the motor. Load = heat and heat = death to your motor.

sideshow wrote:They are the same enough for repair and maintenance purposes. Don't know if you have noticed but a 914 has very different intake and exhaust system and typically specc'ed different from the factory;

http://www.tunacan.net/t4/reference/case.htm

Just saw this....uh...no...the intake on bus, 412 and 914 EFI intake for 1.8's is virtually identical. Only some small differences on the runner joints. TB is the same diameter with small differences for EGR and different vacuum ports. Only the 2.0 914 differs in any great respect.

Ray

I don't think 1.8L 914's had EGR, at least mine in my old 914 didn't and the plenum I got for my type 4 when it was using a modified Ljet intake didn't either.

The EGR was added to any vehicle in California...van...411/412...914...simply by swapping out the plenum on early models....the EGR dumped in near where the MPS nipple was on some, near the cold start valve on others....and at the TB on still others. All simply modified common part #'s. I'm not sure if the 914 had it or not either but it would take minutes to install.

The bus did have a lower redline than the 412 or 914 ....with any induction system. Different cam and different gearing. Ray