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mattcfish
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Joined: October 24, 2006
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Location: Bellingham, WA
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 Posted: Tue Aug 21, 2018 2:12 pm Post subject: Going back to stock exhaust, what will I loose? |
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I'm fixing up my old 71 Westy. She has a 1776, CB big valve heads, and a 2 barrel Weber progressive. I'm considering going back to the stock exhaust system for appearance and reliability. Will I notice a large performance drop?
Where will I notice it most?
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SGKent 
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Location: Citrus Heights CA (Near Sacramento)
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| Posted: Tue Aug 21, 2018 2:23 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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yes you will notice a drop, especially with the larger cylinders. VW detuned the motors to make them run cooler and last longer. It may seem to some that the engine would run hotter but the effect is that less fuel and air can be burned in the engine so the outcome is less heat being generated. Less cracking of the heads, less guide wear and overall an engine that lasts longer. Unfortunately the stock exhaust acts like a power governor. I answer this from first hand experience with my 1971 bay. In the end I chose the stock exhaust because it meant less work rebuilding engines and replacing small stuff that wore out from using the greater power generated by t he engine with an extractor exhaust mounted on it. Same is true for dual carbs VS the PICT series. All that said, while I missed the power I didn't miss the work and increase in reliability. VW made these engines to push bugs and type 3's, ghia's around. The bus was an afterthought for a utility vehicle around town. I think if VW had known the public would be driving 70 mph in the buses they would have gone a completely different route with the bus engine.
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busdaddy
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| Posted: Tue Aug 21, 2018 2:32 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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Yeah, it was called the type 4 
Isn't Gary running a dual tailpipe stock muffler on his?
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Danwvw
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Location: Oregon Coast
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| Posted: Tue Aug 21, 2018 2:46 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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You can for sure try it. However, a lot of folks that know bus engines would not do that combination of parts. I Think if you had some stock valve size heads and good compression 8.5 or better it would have a better bottom end torque.
The stock exhaust will wipe out the top end significantly. And you have done nothing to make up for that.
The big valve heads will wipe out the bottom end and a 1776cc is too small for even 40mm intake valves in a bus.
If your in love with those heads forget the stock exhaust and bump the displacement up as much as you can. I think you can go 92mm bore X 74mm stroke without a lot of machine work. And run Dual Carbs IDF or DRLA or equivalent.
Heater boxes need to be removed with those big valve heads.
One thing you could try if you do as your planning with the CB heads and the stock exhaust is to add 6" velocity stacks or a horn air cleaner to help bottom end.
All this being said I put a stock muffler and heater boxes on my 1679cc (88X69mm) bus engine below and tried different carbs, the smaller I made the venturi's and manifolds the better it performed. Now it has 25mm venturi's in Dual Zenith NDIX-32 Porsch carbs.
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mattcfish
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Location: Bellingham, WA
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| Posted: Tue Aug 21, 2018 3:19 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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I figured as much. Actually the heads are great for top end freeway speeds, she'll do 80+ on the flats pretty easily, but yes, hill climbing is not her strong suit. The main thing is that they don't crack like the stock heads did. Substantially thicker. I've considered putting 1.25 rockers on it, but that would probably just kill more bottom end. Sounds like stock exhaust is a no go. Unfortunately all the extractor systems that are reasonably quiet are getting far too expensive for my taste, plus you usually loose a lot of ground clearance with the less expensive ones.
| Danwvw wrote: |
You can for sure try it. However, a lot of folks that know bus engines would not do that combination of parts. I Think if you had some stock valve size heads and good compression 8.5 or better it would have a better bottom end torque.
The stock exhaust will wipe out the top end significantly. And you have done nothing to make up for that.
The big valve heads will wipe out the bottom end and a 1776cc is too small for even 40mm intake valves in a bus.
If your in love with those heads forget the stock exhaust and bump the displacement up as much as you can. I think you can go 92mm bore X 74mm stroke without a lot of machine work. And run Dual Carbs IDF or DRLA or equivalent.
Heater boxes need to be removed with those big valve heads.
One thing you could try if you do as your planning with the CB heads and the stock exhaust is to add 6" velocity stacks or a horn air cleaner to help bottom end.
All this being said I put a stock muffler and heater boxes on my 1679cc (88X69mm) bus engine below and tried different carbs, the smaller I made the venturi's and manifolds the better it performed. Now it has 25mm venturi's in Dual Zenith NDIX-32 Porsch carbs. |
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Wildthings
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| Posted: Tue Aug 21, 2018 3:43 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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| I bought a set of VW made headers from Bughaus (not really sure here) for my Thing several years back but haven't needed to install them as of yet. Being a VW branded product I assume they might last longer than most and fit better. The tubing size is smaller than is typical of other header brands, don't know how that effects things. |
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Danwvw
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| Posted: Tue Aug 21, 2018 3:45 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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Yes, you just don't want more valve flow it's already outpacing the Carb and for sure a stock exhaust and way outpacing the small 1767cc Displacement. I doubt the engine even has as much pull at maximum torque way you have it as a stock 1600 which tops out at about 74mph.
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mattcfish
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| Posted: Tue Aug 21, 2018 4:25 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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| Danwvw wrote: |
| Yes, you just don't want more valve flow it's already outpacing the Carb and for sure a stock exhaust and way outpacing the small 1767cc Displacement. I doubt the engine even has as much pull at maximum torque way you have it as a stock 1600 which tops out at about 74mph. |
Yeah, but it's not the stock carb. The 2 barrel progressive Weber is basically the same as the one on my 2000cc BMW which has much larger valves. This is a common configuration for those. Yes the VW intake manifold is somewhat more restrictive but the longer runners should actually produce increased bottom end output. Plan B on exhaust will be to use an inexpensive side directed Empi header with the glass pack cut off and a Vanagon muffler installed to quiet it down. https://www.carparts.com/details/EMPI/Exhaust_Syst...lsrc=aw.ds
Not a Sidewinder, not tuned, but inexpensive, I already have all the parts.
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Danwvw
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aeromech
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| Posted: Tue Aug 21, 2018 7:01 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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| busdaddy wrote: |
Yeah, it was called the type 4
Isn't Gary running a dual tailpipe stock muffler on his? |
Why yes he is
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richparker
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| Posted: Tue Aug 21, 2018 7:05 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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I understand your desire for the system you posted, it has good clearance. However in your situation I think your engine will preform better with a merged header, you need the pressure.
If you went VS the Sport is a great muffler. It’s has great clearance, it’s quite and I haven’t noticed any MPG drop or performance drop (with the butt dyno).
http://shop.vintagespeed.com.tw/s.nl/it.A/id.988/.f
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wcfvw69
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| Posted: Tue Aug 21, 2018 7:49 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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I'd consider losing the big heads/valves and make it a nice "stock" 1776. That's what I run in my bus. A "stock" dual port engine with all the original, restored parts mounted. The stock muffler is SSOO much quieter than anything aftermarket. Running all the original, correct and restored German VW parts make it reliable and low maintenance.
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Tram
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| Posted: Tue Aug 21, 2018 7:57 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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Well, first loosen all the fasteners.
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SGKent
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| Posted: Tue Aug 21, 2018 9:09 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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| busdaddy wrote: |
Yeah, it was called the type 4
Isn't Gary running a dual tailpipe stock muffler on his? |
stole the type 4 from a light weight car. Bus really needed an air cooled six of some less costly design than Porsche six. That said, even the T4 is a bit too much for these buses. When I found melted parts in my 091 during its rebuild I asked around on it - common on the bus trans. Parts get so hot in the areas that don't get gear oil circulation that some of the high temp plastic bearing retainers melt. seize the needles, and slowly devour the mainshaft. Bus was always meant to be a utility truck although we all use them otherwise. Speed limit reduced in 1974 and stayed that way until fully repealed in 1995. By then most VW buses were worn out and off the road. No one noticed the high speed heat issues like they do now because most folks didn't go places they could drive the way people drive today. We saw an accident today where a guy ended up in a thick grove of trees during a roll. Tow drivers were trying to figure how to get him back out without one of: cutting the car in pieces, rolling it on its side to fit between the trees, or cutting a tree down.
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Wildthings
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| Posted: Tue Aug 21, 2018 9:57 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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He would want the setup with the heat riser as he is running a center mount carb. |
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Spike0180
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| Posted: Wed Aug 22, 2018 4:59 am Post subject: Re: Going back to stock exhaust, what will I loose? |
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Well, I'll chime in even though pretty much everyone already has. I have a 1776 with stock heads and 3 angle valve job (they flow nice), and I saw significant improvement when I switched to a 1 3/8" merged exhaust from my stock system. Do not go stock. My van was really hard to tune, and I'm not convinced that it made more power anywhere in the power band. My next exhaust will be a VS. I should have gotten one when my wife gave me the chance. 
The suggestion I got when putting my engine together everyone said "Let her flow!" because I was restricting both with my carb and exhaust... I now have bigger carbs and bigger exhaust...  some people just have to learn the hard way.
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jtauxe
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| Posted: Wed Aug 22, 2018 7:16 am Post subject: Re: Going back to stock exhaust, what will I loose? |
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| Tram wrote: |
| Well, first loosen all the fasteners. |
Ya beat me to it, Tram.
| SGKent wrote: |
| ...Speed limit reduced in 1974 and stayed that way until fully repealed in 1995. By then most VW buses were worn out and off the road. No one noticed the high speed heat issues like they do now because most folks didn't go places they could drive the way people drive today... |
Bring back 55 MPH! Save lives, save fuel, save money, and save VW engines!
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Danwvw
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mattcfish
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| Posted: Thu Aug 23, 2018 9:05 am Post subject: Re: Going back to stock exhaust, what will I loose? |
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The VS stuff is very cool. Definitely like the "Abarth".
$450 is a little more than I would like to spend but for Stainless that isn't bad.
I'll weld up my Vanagon/ Empi econo solution and see how it turns out.
or maybe I'll just save my pennies for one of these. How quiet are they vs the stock system?
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Danwvw
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| Posted: Thu Aug 23, 2018 3:07 pm Post subject: Re: Going back to stock exhaust, what will I loose? |
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These Abarth? I don't know. The guy above says they are pretty quiet. I used to run the original steel (not stainless) 4 tips on my 356A and they are a very tough muffler, last a lifetime. Mine was throaty though but a really nice sound.
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Last edited by Danwvw on Fri Aug 24, 2018 8:36 pm; edited 1 time in total |
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