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Sun Jan 23, 2005 6:56 am

Greetings all,

Been doing some reading and noticed the 1.8 Type 4 heads have larger valves than the later 2.0 liter heads.
Would switching to an earlier head be a way to pick up some extra ponies plus open up the exhaust options a bit? (I've got a '79)

Any potential problems with this switch? Machine work necessary? Go EZ on me, I'm new to the aircooled scene.. but I am trying hard :D

Thanks in advance,
Ian

Sun Jan 23, 2005 8:07 am

Just one: Exhaust manifold hookups will probably be different. There are two kinds: Square and oval. If they're both ovals, you're fine.

Sun Jan 23, 2005 9:09 am

As I recall, the 1800cc heads have the round ports which would require a different exhaust than the square ports.

You're correct, the 1800 heads were larger valves, indeed. I'm not sure how much of a difference in power you'd notice with those.

I think the stock 2 liter produces 67 horse power @ 4200 rpm...

Sun Jan 23, 2005 9:15 am

i have 1800 heads on my '79 CA westy. it came with square port heads originally and the hopelessly unavailable CA exhaust.

the swap is easy, the heads will bolt up fine. there will be a change in compression ratio, so this kind of swap should be done as part of a complete rebuild where compression ratio is measured and set. the valve sizes are different, larger on the 1800 heads. the 2l heads have the smallest valve sizes of any type 4. this will not create any problems and may actually make the engine run better provided you get everyhitng right with the swap. the FI system will work fine, make sure you have the threaded hole on the 3-4 side for the FI temp sensor. carbed 1800 heads do not have this hole but any machine shop can modify the head, it is a very simple mod. FI 1800 3-4 heads have the sensor hole, but it is in the wrong place, so you still have to make the mod.

the exhaust swap involves changing a lot of parts, everything from the heater boxes on out, plus 8 pieces of sheet metal/ducting. but since many of the late exhaust are either super expensive or completely unavailable, it makes sense.

Sun Jan 23, 2005 11:50 am

Thanks for the answers, might have taken a lot of reading before I found some of the more obscure information... (eight pieces of engine tin different).
My complete exhaust is coming up for replacement so looking at prices and availability of the parts is one of the motivators for the head switch.

Thanks again,
Ian

Sun Jan 23, 2005 1:58 pm

My 79 has the 1.8 heads with the 2.0. I guess the Po did it for the reason of exhaust parts being hard to find and expensive.

Tue Apr 29, 2008 1:47 am

I have a 1800 sitting in my garage waiting for money to fall from the sky for a rebuild but I've been thinking about the 2L cylinder swap onto the 1800 case but now I'll keep them the same as original. Maybe go up to 1835 or something just a hair larger if need be. I Happened to stumble upon an exhaust setup that looked like a vw exhaust in some old run down falling apart barn about a year ago and then come to find out it was a california special exhaust. Luck find and lucky that I'm a pack rat! About a month after that a friend of mine started griping about needing that exact exhaust for his new bus so I show him and he about had an anurism! I guess now I better check the heads on that 1800 and see what port they are. Probably have the right exhaust in a pile somwhere! That's how I roll

Tue Apr 29, 2008 6:22 am

germansupplyscott wrote: i have 1800 heads on my '79 CA westy. it came with square port heads originally and the hopelessly unavailable CA exhaust.

the swap is easy, the heads will bolt up fine. there will be a change in compression ratio, so this kind of swap should be done as part of a complete rebuild where compression ratio is measured and set. the valve sizes are different, larger on the 1800 heads. the 2l heads have the smallest valve sizes of any type 4. this will not create any problems and may actually make the engine run better provided you get everyhitng right with the swap. the FI system will work fine, make sure you have the threaded hole on the 3-4 side for the FI temp sensor. carbed 1800 heads do not have this hole but any machine shop can modify the head, it is a very simple mod. FI 1800 3-4 heads have the sensor hole, but it is in the wrong place, so you still have to make the mod.

the exhaust swap involves changing a lot of parts, everything from the heater boxes on out, plus 8 pieces of sheet metal/ducting. but since many of the late exhaust are either super expensive or completely unavailable, it makes sense.
yes, I am using AMC/Raby 1800 heads in my Westy. You must check the CR as Scott has mentioned as the 2.0l chamber is slightly different size. Switching over to the early HE's also gives you better heat!

Tue Apr 29, 2008 6:29 am

so after reading this am i correct to assume that the 1.8 heads have the same bore diameter as the 2.0 heads and other than the valve size difference and the square vs. oval ports they will bolt directly up to the 2.0 motor??

man had i known that 3 years ago i would of kept my 77

Tue Apr 29, 2008 2:22 pm

Bleyseng wrote:
Switching over to the early HE's also gives you better heat!
I wonder if it's because the early ones are one-piece and have a larger surface area? I also like the looks of the early muffler as opposed to the late muffler.

Wed Apr 30, 2008 9:39 am

The early H/E have more fins and also are larger in size, capturing more heat from the exhaust..

1800 heads on a 2.0L engine will drop the CR as the head cc of a 2.0 is around 50cc, the 1800 is 55-56cc- the difference is the 12-15cc dished 2.0L Bus piston that the 1800 didn't share.

Have you read my article on making a 1.7/1.8 into a 2.0?

Wed Apr 30, 2008 7:16 pm

where exactly is that 1.7/1.8 to 2L conversion info on your web site jake? I'm looking and not seeing it. Maybe I'm blind. hmm...

Wed Apr 30, 2008 7:45 pm

On my forums under "Jake's Technical articles"..

Thu May 01, 2008 6:29 am

Jake Raby wrote: The early H/E have more fins and also are larger in size, capturing more heat from the exhaust..

1800 heads on a 2.0L engine will drop the CR as the head cc of a 2.0 is around 50cc, the 1800 is 55-56cc- the difference is the 12-15cc dished 2.0L Bus piston that the 1800 didn't share.

Have you read my article on making a 1.7/1.8 into a 2.0?

55~56 cc, is consistent with what my VW 1800 Type 2, cylinder-head combustion chambers were originally, before I increased them to 60·0 ± 0·1 cc, to give 8·0 : 1 compression ratio, with my 1911 cc, VW 17/1800 Type 2 & 4 modified hybrid engine. The factory-stock valve-diameters, are 41 mm inlet & 34 mm exhaust.

Thu May 01, 2008 6:47 am

My Raby 1800 AMC heads with 42x36 valves

I am using 914 pistons set up for a 7.5 to 1 CR.

Thu May 01, 2008 7:05 am

Bleyseng wrote: My Raby 1800 AMC heads with 42x36 valves

I am using 914 pistons set up for a 7.5 to 1 CR.

Only 7·5 : 1 compression ratio! What low-octane petrol do they sell in Seattle, Washington!?! :shock:

Here in Great Britain, 75 RON petrol @ about £1·10 per litre (i.e. circa US$8½~US$9 per US gallon) is the lowest octane available and is probably the most commonly available in Europe, although 92 RON and 97 RON or 98 RON, are also available in some countries.

Fri May 02, 2008 12:19 am

87 octane - Regular unleaded
89 octane - mid grade
92 octane - Super unleaded

Fri May 02, 2008 1:21 am

I was reading the 1.7/1.8 to 2L conversion article on the aircooledtech forum and just wanted to get something understood, basically an understanding. If I have a 1.8 and take it apart and keep the 1.8 case (stock, possibly line bored and cleaned up) and 1.8 heads (rebuilt in my case with the 42x36 valves and the sparkplugs relocated) then add in 2L crank, 2L cam (split duration and all matching parts along with it) H beam connecting rods and 94mm cylinders then I should be running around (if not under) 8.0:1 CR?

Also I was wondering if running it at that lower compression ration makes it more applicable to have a turbo added later on?

If I was doing all that would it be at all beneficial to get a counter weighted crank shaft?

Just looking for some more info. So far all that I've read here and the other forum mentioned has been great and is helping me get a better vision of my future perfect motor!

Fri May 02, 2008 6:40 am

7.5 to 1 works with the Raby 9550 cam and the stock Ljet just fine. CHT's in the 350 range at 75mph driving all day loaded down up and down mountain passes on 87 cheapo gas.

To the poster, forget the CW crank as thats for type 1 engines, type 4s are plenty strong.
Yes, you can use the 1.8 case, heads, but you will need new 2.0L rods, crank, and pistons. The 1.8 cylinders can be bored out to 94mm to match your new 94mm pistons. You will have to CC your heads, set the deck ht etc to properly set your CR on your engine during mockup. Stock cams don't like much more CR as they already run the engine hot.

Turbo? The 94mm setup is alittle thin for proper sealing at the head and tends to leak under boost. Its been done successfully on several 1700 engines and stays together. They used CIS injection setups of a Rabbit along with the turbo, boost up to 15psi.

I think the better setup is a Camper Special using the Ljet injection. Mine loaded down on trips gets in the 25mpg range if I stay under 75mph.
:D
100hp moves the westy just fine and will stay together for a long time.

Fri May 02, 2008 8:27 am

Homework, homework, homework..
Read what people that do this everyday post and those who have experienced their creations have to say as well.

The TIV crank turns 9K RPM in our race engines, ours are not counterweighted and have up to 4 pounds whittled off them and they still live for 4-5 seasons.

In a low speed bus engine the counterweight crank doesn't add any strength or cut down on case wear at all.. Keep in mind, this is the aircooled "Big Block", not the small, throw away version of the VW engine... Its a totally different beast in every way. You need to read for 3-4 months on every site that Google can offer you before you buy a single damn part. If you don't do this you won't come to us until you have already made mistakes that no one else can assist you in overcoming.