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Longy Samba Member
Joined: April 19, 2013 Posts: 54
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Sat May 29, 2021 11:06 am Post subject: Re: Question on exhaust systems. |
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Sure, many times. but you cannot compare it to a BAS Customsport or a SS143. Two different segments.
That CSP can roughly be compared to the hot dog muffler performance wise. It is good for 90ish hp (Done that on a mild 1776) More than that and the back pressure begins to increase more than good is. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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Longy Samba Member
Joined: April 19, 2013 Posts: 54
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Posted: Sat May 29, 2021 2:02 pm Post subject: Re: Question on exhaust systems. |
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Tnx Alstrup... always very informative answers from you ..
I was wondering if there any sense to change the stock one with that CSP for my well running stockist 1600 SP beside of electronic ignition...
Especially, if I decide to change pistons rings and bring down DH to match CR 8:1 |
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richparker Samba Member
Joined: November 24, 2011 Posts: 6936 Location: Durango, CO
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Posted: Sat May 29, 2021 3:01 pm Post subject: Re: Question on exhaust systems. |
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Personally, I really like the VS exhaust system. I’m currently running the Classic Sport on the 2275cc in my ‘71 Westy. My build is mild with 8.13:1 compression, CNC ported 044 heads and a Engle 110 cam. It’s built to push around a bus, not to drag and it’s power ban is nicely matched with the R&P of the stock ‘71 002 transaxle. I live on southwest Colorado and this combo works well while climbing the many hills and mountain passes in this area.
I’m sure I’d get a few more HP with a merged system, I have used them for years in the past. But, what the VS lacks in HP performance it makes up for in styling and sound. The VS tucks nicely under the apron, the pipe exits out the apron cut out and it lays nicely just under the bumper. While a merged system sticks out like a sore thumb. The sound of the VS is throaty while not putting out too many DB. We’ve found it’s much easier to keep a conversation without yelling with the VS compared to the merged systems we were running in the past.
I’m not saying the VS is better then a scavenging system, but it is certainly nice and I feel the pros out way the cons.
Here’s a recent pic I took of the rear of my bus right after I installed a Jemeryrockjock hitch (which is a top notch product too!). All you see is the tail pipe.
_________________ __________
’71 Westy build
Adventure thread
’65 Deluxe Build |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Sat May 29, 2021 3:37 pm Post subject: Re: Question on exhaust systems. |
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Longy wrote: |
Tnx Alstrup... always very informative answers from you ..
I was wondering if there any sense to change the stock one with that CSP for my well running stockist 1600 SP beside of electronic ignition...
Especially, if I decide to change pistons rings and bring down DH to match CR 8:1 |
Ahh, well, yes, a little, It will at least lower the head temps some when your on the freeway and give you a tad more rpm power. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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Longy Samba Member
Joined: April 19, 2013 Posts: 54
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Posted: Sun May 30, 2021 8:56 am Post subject: Re: Question on exhaust systems. |
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Then, beside of BAS exhaust ( 1100€), what would be good replacement performance wise for stock or mild 1600 SP here in Europe; stockist look (pea shooters) with central carb preheating?
TT has a nice one similar to BAS but very pricey and in UK...
Tnx |
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toxicavenger70 Samba Member
Joined: July 28, 2019 Posts: 869 Location: CO
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dgsaz Samba Member
Joined: November 04, 2008 Posts: 579 Location: Phoenix / San Diego
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Posted: Thu Jun 10, 2021 1:13 pm Post subject: Re: Question on exhaust systems. |
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While we are talking about exhaust systems........
Would you expect a change in exhaust, from a 4/1 to a VS muffler set up, to require a change in carburetor jetting.
While we're at it, I was looking at some Knetch style air cleaners for the 912 and read that a change in carb jetting would be needed. Grain of salt?
dgsaz |
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Rome Samba Member
Joined: June 02, 2004 Posts: 9603 Location: Pearl River, NY
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Posted: Thu Jun 10, 2021 6:07 pm Post subject: Re: Question on exhaust systems. |
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Chickensoup Samba Member
Joined: January 06, 2018 Posts: 5368 Location: Good Hope, GA
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Posted: Thu Jun 10, 2021 10:07 pm Post subject: Re: Question on exhaust systems. |
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Alstrup wrote: |
If you really dive into it, it is not that simple.
- Yes, a 4-1 header will generally always pull better peak hp numbers.
- No, a 4-1 header will not always pull better ABP numbers. (Average Power Band)
- A VS muffler, - and especially the newer SS143 version will almost always pull better lower rpm torque numbers, and sometimes even better APB numbers (As long as we are not talking cam durations over approx 250 @ 0,050")
- With a VS muffler it will almost always be easier to avoid the dreaded afr/power drop in the 2800-3500 rpm range (spot dependant on cam)
- 2-1 buggy headers (Bazooka´s) are generally surprisingly "ok" for upper rpm hp up to around 5500 rpm peaks, but absolutely terrible for torque. The torque suffers 10 - up to about 20% compared to a decent 4-1.
- The best of both worlds would be a 4-2-1 header, but that´s not easily doable on a type 1 engine since the primaries will be too long most of the time. With milder cams it - is - possible to find a length around 20-22" where the extraction works, but the secondaries have to be just right, or it will be counterproductive somewhere in the powerband. Most often in the 4800 to 5800 rpm area dependant on the cam duration and actual pipe lengths.
For instance. I´ve seen a customer´s 1914 with 40/35 mm valves in cylinder heads, W125, 44 IDF´s etc,- and a VS sport muffler. That engine absolutely would not pull more than 117 hp and had a wonky power curve because the exhaust was all wrong for the engine.
That very same engine pulls 127 hp with a 1½" Python.
I later built a 1776 with a Web 218/119 cam, ported stock valve heads, dual 36 Dells, etc. 1½" heater boxes, that very same VS muffler (Its actually in the engine combo thread) This cam is basicly 18 degrees milder @ 0,050" This engine pulls 120 hp and has a very nice power curve,,, ohh, and 177-180 Nm torque too.
You gotta hit the sweet spot the parts are made for
Hope this helps.
T |
thank for posting this Alstrup. many people dont know of tuned headers or tri y systems. or the differences between them. or what makes them work.
i was introduced to the tri y when i heard a set on a small block ford. sounded so good... ive yet to hear one on a vdub tho. _________________ -'85 c10 5.3 LS, 222 cam, long tubes, x pipe, 3 inch spin tech's
-'05 B5.5 TDI Wagon 17in sport rims ;EGR + BSM + ASV Delete, Stage-2 Tune, straight pipe
'65 Tourist Delivery Build
'66 RIP
'69 RIP
Hosea 4:6 "My people are destroyed for lack of knowledge" |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Fri Jun 11, 2021 12:48 pm Post subject: Re: Question on exhaust systems. |
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Alright.
Here is a comparison between a 4 into 1 header and a shorty header on a known engine. This is a 1776 w. a post 2021 CB 2239 cam, AA500 heads w. 37,5 x 33 mm valves, 9,1 CR. dual 36 IDF w. 28/32 mm power venturies and a copy A1 1½" sidewinder. The power curve resembles real life within 1 hp peak. The actual curve is a little different too. But good enough for comparison
Red & turquise lines are the A1 copy header.
Blue & green lines are a 1½" shorty header.
As you can see anything below approx 3800 rpm and the shorty header is better anything above approx 3800 rpm and the shorty header looses.
IRL the upper power differences between the two would be much less, but only to visualize the strongsides of the shorty header and why I often recommend these types of mufflers for especially busses.
Now, before everybody comes running with "my engine does "this", I will say that there are of course variations over the subject, because if you had installed a 1 3/8" header with a decent muffler on this here engine you would have seen a behaviure much closer to the shorty header because you would be at the limit of what that header would handle and the simple calculation of displacement X header size x header length = torque then plays a more dominant role.
In fact here is such a simulation
Here the 1 3/8" header with a phat boy muffler are the blue & green lines.
See. but the shorty header is still better down low.
I have not done anything with a 4-2-1 header because from a practical view it is not a usable way to go for the average VW type 1 builder. A type 4 is different. There you can make a nice 4-2-1 header
finally. The more cam duration you have the larger the difference will be between the two. As I touched earlier, a shorty header works well on engines that have peak power below approx 5500 rpm which generally means that cams up to the range of 240 to 248 degrees @ 0,050" are suitable.
Hope this helps. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993
Last edited by Alstrup on Fri Jun 11, 2021 1:21 pm; edited 2 times in total |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Fri Jun 11, 2021 1:01 pm Post subject: Re: Question on exhaust systems. |
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dgsaz wrote: |
While we are talking about exhaust systems........
Would you expect a change in exhaust, from a 4/1 to a VS muffler set up, to require a change in carburetor jetting.
Yes
While we're at it, I was looking at some Knetch style air cleaners for the 912 and read that a change in carb jetting would be needed. Grain of salt?
Depends on the carbs below. If Weber or Solex Pll´s, most likely. If Dellorto´s you may still be spot on.
dgsaz |
_________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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Jason37 Samba Member
Joined: April 21, 2004 Posts: 1027
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Posted: Fri Jun 11, 2021 2:36 pm Post subject: Re: Question on exhaust systems. |
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Alstrup wrote: |
Alright.
Here is a comparison between a 4 into 1 header and a shorty header on a known engine. This is a 1776 w. a post 2021 CB 2239 cam, AA500 heads w. 37,5 x 33 mm valves, 9,1 CR. dual 36 IDF w. 28/32 mm power venturies and a copy A1 1½" sidewinder. The power curve resembles real life within 1 hp peak. The actual curve is a little different too. But good enough for comparison
Red & turquise lines are the A1 copy header.
Blue & green lines are a 1½" shorty header.
As you can see anything below approx 3800 rpm and the shorty header is better anything above approx 3800 rpm and the shorty header looses.
IRL the upper power differences between the two would be much less, but only to visualize the strongsides of the shorty header and why I often recommend these types of mufflers for especially busses.
Now, before everybody comes running with "my engine does "this", I will say that there are of course variations over the subject, because if you had installed a 1 3/8" header with a decent muffler on this here engine you would have seen a behaviure much closer to the shorty header because you would be at the limit of what that header would handle and the simple calculation of displacement X header size x header length = torque then plays a more dominant role.
In fact here is such a simulation
Here the 1 3/8" header with a phat boy muffler are the blue & green lines.
See. but the shorty header is still better down low.
I have not done anything with a 4-2-1 header because from a practical view it is not a usable way to go for the average VW type 1 builder. A type 4 is different. There you can make a nice 4-2-1 header
finally. The more cam duration you have the larger the difference will be between the two. As I touched earlier, a shorty header works well on engines that have peak power below approx 5500 rpm which generally means that cams up to the range of 240 to 248 degrees @ 0,050" are suitable.
Hope this helps. |
This fantastic info, and I feel like an idiot for asking, but what does the shorty header look like? Being a type 3 guy our exhaust combos are extremely limited. I have an older type 3 Thunderbird with a small glass pack on it, that I plan on using on a mild 1800 SP. The other option would be to go to a VS, or the CSP. |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Jason37 Samba Member
Joined: April 21, 2004 Posts: 1027
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Sat Jun 12, 2021 2:19 am Post subject: Re: Question on exhaust systems. |
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I have never seen such a header before. Is it a semi 4-2-1, or how is it assembled down at the collector?
The CSP Python is a nice system, but maybe a little overkill for an 1800 SP engine. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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Jason37 Samba Member
Joined: April 21, 2004 Posts: 1027
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Posted: Sat Jun 12, 2021 5:46 pm Post subject: Re: Question on exhaust systems. |
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My apologies, not a thunderbird, it was made by Cyclone.
Pics
And agreed on the CSP. I ran this for about a month on my 69 notch 20 years ago, so I can’t tell you anything about it. |
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dgsaz Samba Member
Joined: November 04, 2008 Posts: 579 Location: Phoenix / San Diego
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Posted: Sun Aug 22, 2021 10:18 am Post subject: Re: Question on exhaust systems. |
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Vintage Speed has two performance levels of their mufflers. Sport and Super Flow. Sport for engines up to 125 HP and Super Flow becomes restrictive at 150 HP.
What is the effect of running the Super Flow on a 90 HP engine instead of the Sport model. I've seen examples where HP was lost by going to a 4/1 that is too large for the rest of the engine.
Can I assume the sizing in mufflers would do the same/similar?
dgsaz |
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