Pistons and cylinders

[TonyVWVWVW]

Hey guys got a really nice 411 1700. I was reading that if I put 2 L cylinders pistons and heads on that case they won’t play well together? I would appreciate any info if anybody that has done this before. Apparently, from what I’ve read is that the clearances on the case won’t take the larger pistons because of the length of the connecting rod? Thank you, thank you thank you in advance.

[Bruce.m]

The 2.0l pistons need the matching crankshaft & rods. The 1.7 & 1.8 use a shorter stroke crank with different rods. You can fit 96mm pistons designed for the 1.7/1.8 crank, which gets you 1.9l capacity.

The 1.7l heads only match the 1.7l cylinders (smaller OD where there mate with the head). To use on 1.8/2.0 you need to get them machined to open up the bore that the cylinder mates to.

[TonyVWVWVW]

Thanks Bruce…I have the Q code heads from my
1700 411 that have been machined to take 1800-2000 cc heads maybe I will just stick to the stock stuff for this build…this EA 1.7 engine was rated at 80 hp so it will work well in stock configuration..I was actually thinking about using it in my 67 Ghia Vert!!!

[raygreenwood]

Thanks Bruce…I have the Q code heads from my
1700 411 that have been machined to take 1800-2000 cc heads maybe I will just stick to the stock stuff for this build…this EA 1.7 engine was rated at 80 hp so it will work well in stock configuration..I was actually thinking about using it in my 67 Ghia Vert!!!

Do understand. That 80-82hp 1.7L in the 411, 412 and 914 had 8.2:1 compression. Going to dished or flat tops will drop that to ~7.3:1 which will net you about 66 hp. Still not bad but a dog to tune.

Deleting the factory head gasket (which needs to b done on any type 4) with the stock 90mm domed pistons will get you about 8.4 to 8.5:1 and with good tuning can net you right at 88-90hp.

Also bear in mind that the rated 80-82hp was also with fuel injection. That helped alot. Typically with the domed pistons and twin solex carbs you were getting about 76-78hp. Still not bad.

However, with the domed pistons and well tuned carbs and a better more modern ignition (you can use apertronix ignitor and their 42Kv coil and thats much better)....and with a better camshaft...web #73 or a raby 9590 from the type 4 store....you should beable to match or exceed the stock injection.

One of the issues with the 66mm stroked 1.7L engines and the pretty good heads they had...is that moderate compression increases were a HUGE difference in output. Call it 75% of the difference. The other 25% or so is in the fueling. The injection made a difference. The improvements in ignition mainly support those items but significantly increase throttle response at medium to high rpms. If you coupled even the stock ignition with a module and a better coil (the higher compression type 4 engines were barely ignited well enough by the stock coil)...and then controlled with say a CB blck box to get a custom ignition curve....I am betting that is worth a few HP in certain rpm ranges.

An example of the combined compression, ignition and fueling difference is that the same 1.7L base engine in the early bay window bus...with twin solexes and dished pisons hd 7.3:1 compression. This made only about 62- 66hp....and part of that difference is that they changed how they corrected/measured brake hp in August of 1972. Call it 66hp.

This engine had close to the same cam (if not exact), the same ignition system but with a different advance curve than the euro 411 the same twin solexes...but made roughly 16hp less with the lower 7.3:1 compression than the engine did with EfI and 8.2:1 compression.

Then you look at the same high compression system with factory solex carbs on it....it makes about 76-78hp. You can see what the injection does.

Another point is the early 411 cars like 1968-69 with the twin solex carbs and 200mm clutch. They did not make many and they were never imported here. They had (the only one I have seen)....flat top pistons and about 7.6 to 7.8:1 compression.....and made about 68-72hp.

You can see what the compression does.

A lot of people scoff that minor compression changes are not worth chasing. In a type 4....7.3:1 to 8.2:1 is not minor. A 10hp increase with carbs and domed pistons from 66hp dished pistons to 76hp is a 15.2% increase. I call that signifcant.
An increase from 7.3:1/66 hp to 8.2:1/82 hp is a 24.25% increase in hp. I call that significant and it drives like it.

Getting rid of the head gasket and going to about 8.4:1 compression ...as noted will certainly get you to 85hp or slightly more. A better cam, exhaust and ugraded ignition and 90+ hp is not hard to do when well tuned.

So the biggest reason behind why the compression is so significant on the type 4 1.7L is HOW thehigher compression is produced.
The reason is that when the deck height from the factory is measured...AT THE PISTON EDGE/RIM.....the deck height of both the domed and dish piston sucks. Themost commonly measured deck height at the piston edge surrounding either the dish or dome...is 0.075" to 0.079". Most are right at 0.079". That is a HUGE deck!

So....the domes subtract about 3.5cc from the deck volume of a flat top getting you 8.2:1 compression
The flat tops add 3.5cc to the deck volume for the 7.8:1 compression carbed engine....and the dished piston adds right at 3.5cc more to the deck volume. So the dished pistons have right at 7cc more deck volume than a domed piston set and all have a huge nasty deck around the rim of the piston. So with the 0.079" surrounding deck....and dished pistons....thats why you have 16hp less on a dished piston engine.

You can also really improve if you have the wherewithall to have your cylinders machined down to give you a normal deck height around the piston edge of around 0.040". Then ditch that 0.023" thick head gasket...and you are looking at ~8.7:1 compression.

Work hard to find pistons to keep the compression up and you will really like the 1.7L. Ray

[Bruce.m]

If the domed pistons are worn out, you get a decent compression with 96mm pistons (version for short crank). Or swap to 71mm crank & rods (2.0 items), with flat top 94mm pistons & you will also get decent compression with the Q heads. If you’ve already had the heads machined for the wider cylinders, that could be an option.

[Piledriver]

Agreed, get flattop 96s and build a 1911...That solves the low compression problem.

If it was going in a Bus the lower CR of the stock 1800 setup can be a feature.

Measure your cylinders... If you have not bought them yet look to EMW, they can measure them and cut/match length to your spec, then ship. Don't forget to check the block deck, it likely needs cut .010" as well, may get away with it on a 1700 block.

[VIPERGREEN76]

Thanks Bruce…I have the Q code heads from my
1700 411 that have been machined to take 1800-2000 cc heads maybe I will just stick to the stock stuff for this build…this EA 1.7 engine was rated at 80 hp so it will work well in stock configuration..I was actually thinking about using it in my 67 Ghia Vert!!!

Do understand. That 80-82hp 1.7L in the 411, 412 and 914 had 8.2:1 compression. Going to dished or flat tops will drop that to ~7.3:1 which will net you about 66 hp. Still not bad but a dog to tune.

Deleting the factory head gasket (which needs to b done on any type 4) with the stock 90mm domed pistons will get you about 8.4 to 8.5:1 and with good tuning can net you right at 88-90hp.

Also bear in mind that the rated 80-82hp was also with fuel injection. That helped alot. Typically with the domed pistons and twin solex carbs you were getting about 76-78hp. Still not bad.

However, with the domed pistons and well tuned carbs and a better more modern ignition (you can use apertronix ignitor and their 42Kv coil and thats much better)....and with a better camshaft...web #73 or a raby 9590 from the type 4 store....you should beable to match or exceed the stock injection.

One of the issues with the 66mm stroked 1.7L engines and the pretty good heads they had...is that moderate compression increases were a HUGE difference in output. Call it 75% of the difference. The other 25% or so is in the fueling. The injection made a difference. The improvements in ignition mainly support those items but significantly increase throttle response at medium to high rpms. If you coupled even the stock ignition with a module and a better coil (the higher compression type 4 engines were barely ignited well enough by the stock coil)...and then controlled with say a CB blck box to get a custom ignition curve....I am betting that is worth a few HP in certain rpm ranges.

An example of the combined compression, ignition and fueling difference is that the same 1.7L base engine in the early bay window bus...with twin solexes and dished pisons hd 7.3:1 compression. This made only about 62- 66hp....and part of that difference is that they changed how they corrected/measured brake hp in August of 1972. Call it 66hp.

This engine had close to the same cam (if not exact), the same ignition system but with a different advance curve than the euro 411 the same twin solexes...but made roughly 16hp less with the lower 7.3:1 compression than the engine did with EfI and 8.2:1 compression.

Then you look at the same high compression system with factory solex carbs on it....it makes about 76-78hp. You can see what the injection does.

Another point is the early 411 cars like 1968-69 with the twin solex carbs and 200mm clutch. They did not make many and they were never imported here. They had (the only one I have seen)....flat top pistons and about 7.6 to 7.8:1 compression.....and made about 68-72hp.

You can see what the compression does.

A lot of people scoff that minor compression changes are not worth chasing. In a type 4....7.3:1 to 8.2:1 is not minor. A 10hp increase with carbs and domed pistons from 66hp dished pistons to 76hp is a 15.2% increase. I call that signifcant.
An increase from 7.3:1/66 hp to 8.2:1/82 hp is a 24.25% increase in hp. I call that significant and it drives like it.

Getting rid of the head gasket and going to about 8.4:1 compression ...as noted will certainly get you to 85hp or slightly more. A better cam, exhaust and ugraded ignition and 90+ hp is not hard to do when well tuned.

So the biggest reason behind why the compression is so significant on the type 4 1.7L is HOW thehigher compression is produced.
The reason is that when the deck height from the factory is measured...AT THE PISTON EDGE/RIM.....the deck height of both the domed and dish piston sucks. Themost commonly measured deck height at the piston edge surrounding either the dish or dome...is 0.075" to 0.079". Most are right at 0.079". That is a HUGE deck!

So....the domes subtract about 3.5cc from the deck volume of a flat top getting you 8.2:1 compression
The flat tops add 3.5cc to the deck volume for the 7.8:1 compression carbed engine....and the dished piston adds right at 3.5cc more to the deck volume. So the dished pistons have right at 7cc more deck volume than a domed piston set and all have a huge nasty deck around the rim of the piston. So with the 0.079" surrounding deck....and dished pistons....thats why you have 16hp less on a dished piston engine.

You can also really improve if you have the wherewithall to have your cylinders machined down to give you a normal deck height around the piston edge of around 0.040". Then ditch that 0.023" thick head gasket...and you are looking at ~8.7:1 compression.

Work hard to find pistons to keep the compression up and you will really like the 1.7L. Ray

Ray, thanks for this information. I'm building a 1700 with dome pistons. To bad the web #73 and 9590 cams are so expensive.

[Piledriver]

Expensive is relative.

...build two motors in a row and have the non Webcam (not nitrided, Parkerized or Moly coated) and have to replace oil pumps, the lifters, all the bearings and have the crank turned and build them again costs more, not even including your time...

I blamed this on Castrol reformulating GTX to 800ppm ZnP (not announced/advertised/on the bottle) at the time due to Jakes investigations (And will never buy Castrol products again) there was more to it, the taper ground in the lobes, proper radii ground on the lifters etc, but it still sucked. Webcam gets all the cam/lifter details right, and AFAIK the only aftermarket manufacturer of VW cams that nitrides the cams.

Google for "nitrided camshafts" some engines are so hard on cams (Ford 2300cc) that they have about a very low chance of surviving breakin if cam is not nitrided.

[raygreenwood]

Late to reply, but I tend to agree. There are so many unknowns that can screw you up. When working on type 4's...the cost is higher than a type 1 and the basic parts are scarce enough. But the GOOD parts are way too scarce. Its not worth NOT using known to be better parts if you can possibly spend a little more to get them.

An example...so AC.net says $289 for a web 73. Scat says a C-25 (not even saying whether they are equal or not) is $120. Not even talking lifters yet as they are roughly the same cost give or take.
But the cam difference is $169. Yes that seems like a lot of money but in the realm of a $4-5000 build if you have good parts in there (good quality bearings, $2000 in heads, $500 in NOS domed pistons and cylinders adn maybe a set of ARP bolts and not to mention machine work)..... that $169 extra is only 4.2% of a $4000 build.
The whole camshaft cost of a web 73 is only 7.2%.
Yeah, I know it all adds up fast. But....it can also destroy itself even faster. Ray