stroke and crank case pressure?

[wbx]

A few months ago, a built a 2324 engine for my '84 vanagon (yeah, water cooled... sorry ), and have put close to 2k miles on it by now. This is a waterboxer, so it has a great many similarities to all the ACVW engines out there, which is my reason for asking here...
The main displacement increase (stock is 2106) came from stroking it out from a 76 to an 82. Other possibly related mods include total seal rings, bigger valves, and an admittedly (relatively) restrictive air filter/intake system. My concern is what all this may have done to crankcase pressure and perceived power.

Early on, i had some oil bypassing the main pulley seal. I havn't seen that lately, but i also havn't driven the van hard at all. The other symptom (evident in a stock engine, but more pronounced now) is that there can be a fairly large discrepancy in the amount of available power on the highway. What i mean is, if you've had your foot in it, and then let off for a little bit (ie. going over a long grade), there isn't much "pep" when you get on the gas again. Compared to a nice flat stretch at the same speed, requiring little throttle, once you get on it, the van does too. The only difference between these two scenarios being the earlier load requirements.

Is this even related? And if not, what would cause the HP difference given the two different scenarios. What are other effects of what is going on inside the engine when you stroke it out pretty much as far as it'll go?

Thanks for any insight,
-Damon

[ANT]

Anytime you increase the displacement you raise the needed amount of crankcase ventilation.

Your power question is trickier.....perhaps it's a carb problem or even a timing issue. Have you rejetted or recurved?
-ANT

A few months ago, a built a 2324 engine for my '84 vanagon (yeah, water cooled... sorry ), and have put close to 2k miles on it by now. This is a waterboxer, so it has a great many similarities to all the ACVW engines out there, which is my reason for asking here...
The main displacement increase (stock is 2106) came from stroking it out from a 76 to an 82. Other possibly related mods include total seal rings, bigger valves, and an admittedly (relatively) restrictive air filter/intake system. My concern is what all this may have done to crankcase pressure and perceived power.

Early on, i had some oil bypassing the main pulley seal. I havn't seen that lately, but i also havn't driven the van hard at all. The other symptom (evident in a stock engine, but more pronounced now) is that there can be a fairly large discrepancy in the amount of available power on the highway. What i mean is, if you've had your foot in it, and then let off for a little bit (ie. going over a long grade), there isn't much "pep" when you get on the gas again. Compared to a nice flat stretch at the same speed, requiring little throttle, once you get on it, the van does too. The only difference between these two scenarios being the earlier load requirements.

Is this even related? And if not, what would cause the HP difference given the two different scenarios. What are other effects of what is going on inside the engine when you stroke it out pretty much as far as it'll go?

Thanks for any insight,
-Damon

[wbx]

Anytime you increase the displacement you raise the needed amount of crankcase ventilation.

ANT, carbs are SOOO 70s!

Your power question is trickier.....perhaps it's a carb problem or even a timing issue. Have you rejetted or recurved?
-ANT

I am using the stock fuel injection from a 1.9 engine, so there has certainly been some tweaking to make that work, but timing has been left stock. That is definitely my next project - building a megasquirt EFI system, but what confuses me is that, even with the stock engine, it had that weird power thing. It is just significantly more pronounced now with the increased displacement...

Thanks for the ventilation bit, though... i looked through the archives and just need to figure out what is the best option for my bus. Is there anything else it could be, you think?

-Damon

[ANT]

FI, like any other computer system lives and dies by the axiom "GIGO"

Garbage In, Garbage Out.

They're only as good as the information given them, and the alogrithims that drive them.

If you don't have a MAP or BARO sensor (or even an O2 sensor) then you'll be straddled with an unresponsive system unless you completely plot the needed maps. And that alone would take a gang of Cray computers!

Once a carb is dialed in, you're done. Until the day it wears out or gets clogged that is. No need to worry about sunspot activity or stray EMP's that the future mind police may blast your way.
-ANT

Anytime you increase the displacement you raise the needed amount of crankcase ventilation.

ANT, carbs are SOOO 70s!

Your power question is trickier.....perhaps it's a carb problem or even a timing issue. Have you rejetted or recurved?
-ANT

I am using the stock fuel injection from a 1.9 engine, so there has certainly been some tweaking to make that work, but timing has been left stock. That is definitely my next project - building a megasquirt EFI system, but what confuses me is that, even with the stock engine, it had that weird power thing. It is just significantly more pronounced now with the increased displacement...

Thanks for the ventilation bit, though... i looked through the archives and just need to figure out what is the best option for my bus. Is there anything else it could be, you think?

-Damon

[wbx]

Well, i can certainly agree with what it is you are saying about GIGO, but one of the things EFI has a tendency for more than carbs is consistency (although definitely not all the time!). All the sensors are known good, and it doesn't *feel* like an FI problem (if that makes sense?). Electrical things tend to be more, um... well... digital. Power or no. Obvious problem or not (even if what the problem is isn't so obvious). This is certainly a gross oversimplification, but fairly applicable to my situation.
The power gradually comes and goes, not something an electronic sensor would tend to show as a failure mode.

You might be on to something with the EMPs, though. Is there a sensor or inhibitor you can get for those?

-damon

p.s. i'll still stick with FI over carbs any day...

[ANT]

Check all the ground leads.....add some if you wish (you literally can never have too many). Perhaps under certain conditions the engine is moving just enough to cause a loss of ground. I dunno, but have seen similar sceanarios.

Not sure what flavor of TPS you're running, but these can exhibit the wonkiest of behavior too, same applies to air flow meters. Don't forget to check for rips in the air boot....sometimes these come into play when the engine moves about just so. And always keep an eye out for vacuum leaks.
-ANT

Well, i can certainly agree with what it is you are saying about GIGO, but one of the things EFI has a tendency for more than carbs is consistency (although definitely not all the time!). All the sensors are known good, and it doesn't *feel* like an FI problem (if that makes sense?). Electrical things tend to be more, um... well... digital. Power or no. Obvious problem or not (even if what the problem is isn't so obvious). This is certainly a gross oversimplification, but fairly applicable to my situation.
The power gradually comes and goes, not something an electronic sensor would tend to show as a failure mode.

You might be on to something with the EMPs, though. Is there a sensor or inhibitor you can get for those?

-damon

p.s. i'll still stick with FI over carbs any day...

[Gabriel]

IMHO your fuel injectors are undersized for your new capacity:the original
025 906 031 (VW) / 0280 150 206 (Bosch) injector, installed on both 1.9 and 2.1 WBX is already sized a bit "borderline" for the 2.1 engine.
This cause the lack of power at top end the lack of grunt when you push on the pedal because the injectors cannot supply the fuel required by the Digifant unit operating in "acceleration pump" mode.

good luck

Gabriele