Any performance loss using 1.8 heads on 2.0 Options

[Badass43]

Hey Guys,

I bought an engine from the classifeds here and was told it was a good engine but have found out it needs to be rebuilt.

I need to know if I get 1.8 heads for this 2.0 will I suffer any loss of power?

I found a small crack on the one head I have removed so far. the crack is right next to the plug hole.
I know I should have this fixed if I reuse these heads but has anyone reistalled heads with these small cracks with success?

I can get these heads that are pictured that say they are 2.0 heads but they look like 1.8 heads. Do you think they might be 2.0 bus heads?

What do you guys think?

Randy

[Rick L]

No. The mating surface volumes and valves are the same for both heads.

[VaccaRabite]

You will loose power going from 914 2.0 heads to 1.8 heads or 2.0 Bus heads.

The heads pictured are bus heads. 914 2.0 heads have three bolts on the intake.

Are you sure that it is not cheaper to get your 2.0 heads fixed then buy a questionable set of heads that you know are de-tuned?

Zach

[Badass43]

I don't know, what is the average price to have a set of heads reworked?

Who would I send them to?

Randy

[Todd Enlund]

Those are 1.8 heads. 2.0 bus heads have a smaller combustion chamber with smaller valves (used with a dished piston). For the definitive answer, measure the intake valve. The 2.0 bus had tiny little 37.5mm intake valves, the 1.8 had 41mm. For comparison, the 914 2.0 had 42mm intake valves. The 914 2.0 heads have only three intake studs, so it's easy to tell them from the others.

[davep]

Len Hoffman at Ham Inc can fix your heads.
forum name "HAM Inc"
http://www.haminc.biz/
Both valves and ports are larger on the 914 2.0 heads.
The 914 2.0 heads also have a much better spark plug location.
Len can modify your 1.8 heads to improve all three areas, but it may cost less to start with the 2.0 heads.

[SLITS]

The 2.0L head was specifically cast by Porsche/VW to improve flow and flame travel. The ports are different and the spark plug was relocated for better combustion.

Small valve heads are generally good for lower RPM and torque, but they lose on the upper end of the RPM range.

The dish in the piston is deeper for a bus engine than it is for a 914 engine.

Going to 1.8 heads ... your 2.0 sheetmetal (cylinder covers) will not fit due to sparkplug location and your intake runners will not work without redrilling the holes.

I was told by a VW guy that cracks in the sparkplug are are not the major concern ... an engine can be run with them. The cracks growing in size is a major concern and ANY cracks in the combustion chamber roof heading for either of the valve seats or ports is a time bomb waiting to go off.

OK John or Jake ... fire away

[Rav914]

From Jake's 1.7 > 2.0 conversion article:

"Other heads" that can be used with the 1.7>2.0 conversion:
Now that you have upgraded to the 94mm cylinders (or 96mm) you are no longer limited to the small 100mm OD registered heads of the 1.7 engine. This means you can bolt on a set of 1.8 or 2.0 heads and if you go this route you won;t need to do ANY machine work to the heads at all for them to match perfectly to the 2.0 cylinders.

Ultimately I feel the best heads for these 2.0 conversions come from the 1.8L engine. These have the largest stock valves of any OEM head and the lack of machine work that is necessary make them a bit cheaper, especially for guys that are choosing to work on a budget, keeping as much "stock" as possible. Of course you should have any head completely rebuilt with new seats added- If you choose 1.8L heads you can keep the valve sizes stock at 41X34, or you can upgrade the components to 42X36 (my favorite valve sizes for small displacement engines) and use our modern parts for the job.

The 2.0 Bus or 914 heads are also worthy units, but most of them must have repair work made because the Bus heads come from overworked engines that have been pushing 5,000 pounds for 30+ years. We stay away from rebuilding any heads that came from a Bus engine as most have irreparable damage or damage that will cost more than the heads are worth to repair. The 2.0 914 heads are the only real "Porsche" heads found on the Type 4 engine. They feature 3 stud intake manifolds, the largest chambers and their own spark plug location. These are the most rare heads and also the heads that have the weakest combustion chambers, 95% of the time they are cracked and require machine work and a full rebuild. They are the most expensive heads to work with- period. They will make the most power of any stock head, due to the plug location, valve sizes and combustion chambers but the performance comes with a cost."

[davep]

1.8L heads have valve sizes, stock, of 41X34
2.0L 914 heads have valve sizes, stock, of 42X36
Ports ARE different also.

[james2]

Not sure what you wallet looks like, but the CNC heads Jake have are pretty nice. I looked at them in person and on the dyno.

Heads will make more difference in HP than any other item.

[Badass43]

I have seen those heads on Jake's site, but my pockets aren't that deep. If they were I would have just ordered a new engine from Jake as it seems his engines are the best around.

I bought my whole car for less than a Raby engine but I guess you have to pay for that kind of quality.

I would just like to get this engine running so I can replace my 1.8L.

The whole purpose for replacing the 1.8 is I want more power.

My biggest concern right now is do I rebuild the engine or just rering it, replace all seals & gaskets and run her.

I just need to know if when you turn the flywheel by hand if feeling a little play is normal. I removed the #1&2 cylinder head and if I pull out on the pistons I don't feel any play in the rod bearings or wrist pins but I still need to remove the other head and check 3&4 pistons for play in the rod bearings or wrist pins.

I need to save money for other projects on my plate but I would hate to go through all the trouble of changing engines just to blow this thing up in a short time.

Randy