1.8 to 2.0 hop-up advice

[Steve Frankiewich]

I have a stock '75 1.8 with the fuel injection. I want to make a fairly simple performance up-grade by installing some good used 2.0 pistons, cylinders and heads. I need some advice:

1. Is it worth putting on the 2.0 heads rather than the 1.8?

2. Do the heads affect the compression ratio or is there a difference due to the piston crown?

3. I'll have the cylinders honed and install new rings. Anything else?

4. Will I need to do any machining to install the cylinders in the block or to the 1.8 heads if I retain them?

5. I never take the engine close to redline so will the stock injection be adequate?

Thanks for any advice.

Steve Frankiewich
Victorville, CA

[Bleyseng]

First, How many miles are on this engine? The bearings (mains and rods) condition dictate whether you can slap on a new top end. I don't think you can bolt up the 2.0L (94MM) P&C's as they have a different pin offset. Installing 96mm P&C's with the correct wrist pin offset for the 66mm stroke will get you to a 1.9L engine. 96mm P&C's slip right in to the case.

Most of the 96mm P&C's are flat top pistons so you would need to set the deck heights to get the right compression ratio, no more than 8.5 to 1.
If you install the 2.0L heads, you also need to install the 2.0L cooling tin (1.7 & 1.8 use a different type). Probably also need to drill the FI intake manifolds for 3 bolt or find a set of 912E manifolds so you can keep the L-jet. The 2.0L heads will give you better breathing due to their design but what a pain to change all this. Why not just get the 1800 heads rebuilt with 42x36 valves with a port and polish to gain some HP and some flow.
As you can see, it's not easy to just grab pieces from here and there and get lots of HP.
I would rather take the whole engine apart, installing new bearings, cam, lifters, balancing the rotating parts, if I am installing different P&C's and heads. That way I know the motor will last and be trouble free, atleast the rotating parts.
Geoff

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76 914 2.0L

[SteveStromberg]

If you are using 2.0 pistons on a 1.8 crank and rods you will have a comp. ratio of about 5.3 to 1 as the PCH is less on 2.0 pistons.I have some 96mm pistons used that will bolt on to your 1.8 heads and rods,I will swap for 3 bolt 2.0 heads.Steve www.914underground.com

[JP Noonan]

You might be better off with new stock 1.8L p/c's and the 2.0L heads. Or new 96mm 1.8L P/C's for $350 or so and the 2.0L heads. Not only do they have slightnly larger valves than the 1.8L the port design is much better and the spark plug angle is different for more power. All 1.7 and 1.8L heads are about the same between the VW and 914, but the 914 2.0L heads ONLY came on 914's and are considered by most rebuilders to be Porsche heads because that is who designed them even if they have a VW part number. They also have BOTH intake AND exhaust sodium filled valve stems.

That being said, 2.0L 914 heads are more prone to cracking due to the spark plug angle and have been accused of dropping seats more frequently. A set of PROPERLY ported, polished, and flowed 1.8L heads should meet or exceed stock 2.0L heads, but it will cost more.

My 1.5 cents

[jabb]

Why not get a complete 2.0 Core motor and
rebuild that with the Euro pistons and
slight cam modifications, usingthe stock
FI. You can keep your car running with
the 1.8 until the new motor is ready.

Joe A

[sammyg2]

The 2 liter heads have sodium filled intake valves? I didn't know that, I thought it was just the exhaust side that was sodium filled. Learn something new every day.
Anywho, I agree with the previous posts, sell the 2 liter heads and get some good 96mm p/c's. Good 2 liter heads are worth big $$$ on evil-bay.
If you never take the engine to redline like you said, then you probably won't ever notice the difference between the 2 liter and 1.8 heads.
The 2 liter heads flow more air, but that doesn't make as much difference at lower rpms. If you don't want to spin the motor faster, then the only way to increase horsepwer is to increase displacement, or volumentric efficiency (taking a bigger gulp of air per stroke).
A slight increase in compression ratio will help, but you shouldn't go too far with that.
Like they say, there is no substitute for displacement (except for forced indiction).

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Gerald Gore II (Sam)
73 914 350 small block

[Dave at Pelican Parts]

Nope, the stock intake valves are not sodium-filled--just the exhausts. I'm not even sure that sodium-filled intake valves are available for the motor... Perhaps exhaust valves from some other motor would be the right size, but I'm not sure I see the point. The exhaust valves are the ones with the real heat problems, not the intakes.

--DD

[JP Noonan]

Well, I've been wrong before (I believe it was a Tuesday), but I'll try to track down where I got the impression the 2.0L had sodium intakes. I beleive it was Tom Wilson's book, that and the high price and thick stems of the 2.0L intakes.

I do have some old 2.0L valves I could drill a hole into.... just kidding.