TheSamba.com :: View topic - 36hp Rebuild with WW Okrasa Kit in Bus

Sun Jul 17, 2016 10:10 pm

Picture of original muffler vs. after market ones:

Sun Jul 17, 2016 10:42 pm

tobiasax wrote: EVfun wrote:
I noticed that AA sells slip in 80mm cylinders that will fit in a 36 horse. The problem is they don't sell pistons to make that an easy upgrade. )

The outer diameter of the cylinder foot of a 36hp cylinder is 81,8 mm. If someone try to sell you 80mm bore slip-ins be aware! A cylinder wall thickness of 0,9 mm is a tad to thin in my mind...
Noted. Here is the entry on the AA web site. They look thin, but 35 thou seems a bit to thin!

Mon Jul 18, 2016 8:13 am

Just for an update on the build I am doing for the 15 Window.. Everything is ordered up except for the exhaust and I should be doing that today.

- WW Okrasa Kit w/ CSP Linkage
- Aircooldresearch Stage 1 Cam
- Flat4 FRAM External Oil Filter
- Going to send / exchange the carbs in the WW to Mr. Okrasa for his that are re-bushed / re-jetted
- Vintage Speed single tip 25/36 Muffler

I've spoken with a fantastic local guy from this thread who will be rebuilding the 36 short block and putting the WW Okrasa kit on for me at the same time.

This should get me the little bit of gains I am looking for and if I figure out the split trans / rgbs are really holding me back I'll look into a later tunnel / small nut transmission and rgbs.

Mon Jul 18, 2016 9:12 am

EVfun wrote: tobiasax wrote: EVfun wrote:
I noticed that AA sells slip in 80mm cylinders that will fit in a 36 horse. The problem is they don't sell pistons to make that an easy upgrade. )

The outer diameter of the cylinder foot of a 36hp cylinder is 81,8 mm. If someone try to sell you 80mm bore slip-ins be aware! A cylinder wall thickness of 0,9 mm is a tad to thin in my mind...
Noted. Here is the entry on the AA web site. They look thin, but 35 thou seems a bit to thin!

Has anyone run these AA slip-in to know first-hand of issues? I'm just curious if anyone has run them and whether they are having distortion issues or other?

Mon Jul 18, 2016 9:18 am

tobiasax wrote: Alstrup wrote:
Exhaust. DEFINITELY find one better than the stock one. I´m not especially impressed with the VS mufflers, but on the other hand they are decent for the money. Or you could build yourself a "bus abarth" :-)

What's the problem with the stock muffler? An original Volkswagen "logo" muffler has no internal restrictions and features equal length primary pipes. Cut one open and you'll see! Just add a pair of free flowing end pipes and you have a real nice exhaust system.

As far as I know neither Abarth-replicas nor VS have equal length primaries, but I have heard that the new stainless mufflers from CSP have it.
tobias, maybe the older factory mufflers are like that. I am no expert on them, at all. The newer ones have baffles and restrictions.

T

Mon Jul 18, 2016 1:50 pm

Alstrup wrote: tobiasax wrote: Alstrup wrote:
Exhaust. DEFINITELY find one better than the stock one. I´m not especially impressed with the VS mufflers, but on the other hand they are decent for the money. Or you could build yourself a "bus abarth" :-)

What's the problem with the stock muffler? An original Volkswagen "logo" muffler has no internal restrictions and features equal length primary pipes. Cut one open and you'll see! Just add a pair of free flowing end pipes and you have a real nice exhaust system.

As far as I know neither Abarth-replicas nor VS have equal length primaries, but I have heard that the new stainless mufflers from CSP have it.
tobias, maybe the older factory mufflers are like that. I am no expert on them, at all. The newer ones have baffles and restrictions.

T

That's true, you need to find an old NOS one, but that's not impossible. I did put in a wanted ad and bought a logo muffler within a week. Soon after I found a second one on a fb group which a friend of mine bought. In both cases way cheaper than a stainless steel exhaust.

Mon Jul 18, 2016 3:28 pm

running sweet. and going in this week i hope. ill tell ya all how it runs !

kept the patina look cuz the bus is not going to be restored.

Mon Jul 18, 2016 3:30 pm

tobiasax wrote: What's the problem with the stock muffler? An original Volkswagen "logo" muffler has no internal restrictions and features equal length primary pipes. Cut one open and you'll see! Just add a pair of free flowing end pipes and you have a real nice exhaust system.
This is what I did. VW logoed muffler and some old stock Superior down turns. I tried some straight pipes but to loud. With the down turns it muffles it enough to sound good and you can still carry on a conversation with your passenger.

Mon Jul 18, 2016 8:54 pm

tobiasax wrote: Picture of original muffler vs. after market ones:

Most certainly the VW factory mufflers are superior to the aftermarket ones. These rather large can type mufflers count on a "pillowing" effect to allow the exhaust pressure to compress slightly, before exiting the exit tips at an even rate. Another benefit is that the sound reverberation is captured in the can, and not allowed to go back up the the exhaust tract, wreaking havoc in the combustion chamber due to cam/valve overlap. The problem with the VW muffler is that the pillowing effect needs more room than the can has in even slighty higher rpm's. Space constraints dictate the size of the can. As an example, look at the size of Porsche 356 factory mufflers. Easily more than twice the size of VW, even on 1100 & 1300 cc engines with redlines starting at 4500rpm. Some relief can be had for VW with special exhaust tips for bug, but nothing for the poor bus.
Header systems are actually "extractor" systems, meaning that the exhaust pulse from one cylinder creates a small vacuum in the collector, on a properly designed system (Rodger Bursh perfected this for 356 with his 2 into 1 collector in the '60s) Careful bending of the pipes disallow sound pulses to travel back. This scavenging effect can allow lower throttle openings at higher cruising RPM because the "pillow" is not too compressed by the small can. This scavenging is also the reason that fitting slighly larger jetting is oftenrequired. Low end torque reduction with extactor exhaust is negligible, due to the tiny intake tract keeping velocity high. Ridiculous cams excepted.

Tue Jul 19, 2016 3:27 am

hoss wrote: Just for an update on the build I am doing for the 15 Window.. Everything is ordered up except for the exhaust and I should be doing that today.

- WW Okrasa Kit w/ CSP Linkage
- Aircooldresearch Stage 1 Cam
- Flat4 FRAM External Oil Filter
- Going to send / exchange the carbs in the WW to Mr. Okrasa for his that are re-bushed / re-jetted
- Vintage Speed single tip 25/36 Muffler

I've spoken with a fantastic local guy from this thread who will be rebuilding the 36 short block and putting the WW Okrasa kit on for me at the same time.

This should get me the little bit of gains I am looking for and if I figure out the split trans / rgbs are really holding me back I'll look into a later tunnel / small nut transmission and rgbs.

This is a really good approach, I think you'll have success with a plan like this

Tue Jul 19, 2016 11:34 am

Ultramoron wrote: hoss wrote: Just for an update on the build I am doing for the 15 Window.. Everything is ordered up except for the exhaust and I should be doing that today.

- WW Okrasa Kit w/ CSP Linkage
- Aircooldresearch Stage 1 Cam
- Flat4 FRAM External Oil Filter
- Going to send / exchange the carbs in the WW to Mr. Okrasa for his that are re-bushed / re-jetted
- Vintage Speed single tip 25/36 Muffler

I've spoken with a fantastic local guy from this thread who will be rebuilding the 36 short block and putting the WW Okrasa kit on for me at the same time.

This should get me the little bit of gains I am looking for and if I figure out the split trans / rgbs are really holding me back I'll look into a later tunnel / small nut transmission and rgbs.

This is a really good approach, I think you'll have success with a plan like this What fun! looking forward to reports on how it works . If you think about a trans swap in the future I've got a "core" trans available. But hopefully you won't need to do that...

Tue Aug 23, 2016 3:49 am

I also run an original VW exhaust on my 36hp WW okrasa, but I removed the preheat pipes from the muffler completely, normally this pipe runs into the left exhaust pipe and would give some restriction. Now removed and should give a bit more flow

Tue Aug 23, 2016 12:08 pm

Jacks wrote: Most certainly the VW factory mufflers are superior to the aftermarket ones. These rather large can type mufflers count on a "pillowing" effect to allow the exhaust pressure to compress slightly, before exiting the exit tips at an even rate. Another benefit is that the sound reverberation is captured in the can, and not allowed to go back up the the exhaust tract, wreaking havoc in the combustion chamber due to cam/valve overlap. The problem with the VW muffler is that the pillowing effect needs more room than the can has in even slighty higher rpm's. Space constraints dictate the size of the can. As an example, look at the size of Porsche 356 factory mufflers. Easily more than twice the size of VW, even on 1100 & 1300 cc engines with redlines starting at 4500rpm. Some relief can be had for VW with special exhaust tips for bug, but nothing for the poor bus.
Header systems are actually "extractor" systems, meaning that the exhaust pulse from one cylinder creates a small vacuum in the collector, on a properly designed system (Rodger Bursh perfected this for 356 with his 2 into 1 collector in the '60s) Careful bending of the pipes disallow sound pulses to travel back. This scavenging effect can allow lower throttle openings at higher cruising RPM because the "pillow" is not too compressed by the small can. This scavenging is also the reason that fitting slighly larger jetting is oftenrequired. Low end torque reduction with extactor exhaust is negligible, due to the tiny intake tract keeping velocity high. Ridiculous cams excepted.

Good point. I figure as VW did use about the same physical size muffler up to the 1600cc's, it would be good enough for my 1300cc. With a slightly simplified calculation I came to the conclusion that a 1600cc at 4000 rpm (peak power) pumps as much air/exhaust as a 1300cc at 5000 rpm, which is good enough for me. If you have a bigger engine and/or a hotter camshaft the original VW muffler might be too small.

Wed Aug 31, 2016 12:11 pm

Almost Labor Day Update

- Rebuild is done! Thanks Steve!
- Tins should be ready to pickup from powdercoat in the next day or two
- Received the carbs back from Joe Ruiz and he did his full treatment on them

I should be able to start assembling soon. Will update with pictures as it goes together.

Super stoked. Goal is to have it ready for Solvang in late September.

Sun Sep 11, 2016 4:42 pm

Hey guys.. I'm assembling and everything is going together great.

I do have one question. I picked up the Flat4 Fram Oil Filter kit. I'm running the CSP linkage with the WW Okrasa kit, so I can't use the distributor clamp stud to hook the oil line to, as the CSP linkage bracket covers this.

I talked to Shin, and he showed me on his engine with CSP that they drilled and tapped the back of the generator stand.

Is this the recommended spot if running the CSP linkage with the Fram setup? What size drill and tap do I use?

Thanks!

Sun Sep 11, 2016 5:09 pm

maybe you can trim the bracket back some. it's thicker than it needs to be. you can drill and tap into the stand. back// side/ front doesnt matter. i would use grease on the drill and tap to keep chips from getting in the motor. :wink: / if your going to use the stud in the stand it is 8x1.25 the tap will tell you what drill size.

Mon Sep 12, 2016 8:13 am

sgmalt46 wrote: maybe you can trim the bracket back some. it's thicker than it needs to be.

Drilling the case makes me a bit nervous. I'll look at the bracket and see if maybe it can be modified a bit to accommodate the distributor stud hose fitting.

Sat Sep 17, 2016 11:50 pm

Just finished assembling everything tonight. Hopefully going to install tomorrow!

Sun Sep 18, 2016 5:47 am

Sweett...just wonder how the oil filter is going to be serviced...

Sun Sep 18, 2016 5:39 pm

hoss wrote:

Just finished assembling everything tonight. Hopefully going to install tomorrow!
filter looks too high? is it going to fit?