About 10 years ago my stock '75 1.8L L-Jet was rebuilt. A 2L crank was installed along with 94mm pistons.

Can runs good, slows down quite a bit on hills. My mechanic has suggested replacing the cylinders/Pistons with 96mm. The engine would be kept FI with the L-Jet

Does this make sense and would other mods be required ?

96mm over 94mm won't make a difference, at least not noticeable.
I wouldn't change unless you need new P&Cs.

L-jet is what it is, smooth running, predictable, but it's not a powerhouse.

The only cheap mod that will make good, noticeable improvement is a set of headers...but then you will lose heat.

Jim lives in Sunset beach, really no need for heat.

Your current cylinders can be bored & honed to fit 96mm pistons....they're likely better quality and certainly more thermally stable than new ones would be....

Thanks for that analysis, you pretty much said what I have read over the years. A local here, with a L-Jet like mine, installed the Tangerine headers and it seemed to have made a nice improvement.

I disagree.

The L-Jet on Betty's 914 is great. It is smooth and reliable. And it is the basis for the Motronic system used on all current Porsche cars.

The biggest problem with a stock motor is breathing. Bigger valves, a different cam, and a bigger throttle body does wonders for a 914 with L-Jet. I put a Raby 9590 cam in Betty's car, along with 2.0 valves in 1.8 heads and a Bus throttle body.

Doing that woke up the motor. It pulls strong all the way to redline.

Are the 2.0 valves direct replacements, or does other work need to e done on the head.?

In my opinion, like a computer, it's possible that it seems slower....

I would suggest you do two things, both are in your quest to solve the problem, but will provide you with a fun summer.

First, run some simple water through the engin while it's running.
Use the 1/8 vacuum advance hose for the distributor while its warmed up
Slowly run about a liter of water though the engine, outdoors.
It will steam clean th Carbon out, so there will be lots of smoke...

Then give it a tune up.


Second,
Find a core motor and build a 2270 to get more power as you want.
Mark could do it, or EMW could do it...or FAT...

Rich

I don't mean that in a bad way, I have a 914 2.0 with L-jet here and it's every bit as powerful as a D-jet. In fact it's a hoot, may be the kick in the pants I needed to get my 3.0 914 finished.

I'm also biased as I've never driven a stock engined aircooled anything, at least not for very long.
I guess driving a 180hp 2.6L T4 in a 1700lb VW bug has me a tad spoiled.



You would have to replace the seats. I'd get real 2.0 heads and do a straight swap. Still not anywhere near the gain of a set of headers.

Hi Jim, I thought when I drove your car last year at the WCR it pinged a bit while going up a few of the hills.


No input on a motor build, doing one right now so I'll keep an eye on what others suggest.

Tangerine Headers - you can keep heat heat if that is a requirement. Chris does great work and the only Issue I see with these works of art is, you want to put a mirror under your car, and keep it on jack stands. :drooled:

For your sanity, clean everything up, take a picture, poster size it hang it on the wall and

After that, I would suggest a cam, Heads, the 1.8L are pretty good, with some work done to them. And L-Jet is not a bad system. Ran one on a 1911 motor, loved that -4 it would spin up fast, great little auto-x motor, not bad on the street.
L-Jet, Mallory, and a set of Kerry Hunter Headers, switched to european Racing, which where better, made my last switch to Mr. Foley's headers and never looked back. Get them well worth the $$$$.

That being said, I would ITB the motor and run and EFI system on the car.

Header
Cam
Bigger Valves
EFI and Ignition Dub Shop EFI

I remember that; interestingly that was the only time that occurred. The recent drive to Flagstaff was ping-free and there was similiar opportunities.

I do have the Mallory Uni Lite installed and a pair of 1.8 heads coming after Fat Performance resurfaces them and cleans them up

Lots of terrific suggestions....really appreciate