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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7215 Location: Videbaek Denmark
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Posted: Tue May 24, 2022 12:49 pm Post subject: Re: Sidewinder 'Dip' |
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An O2 sensor is the basic tool IMHO, but it will never make up for a dyno sessoin. There are things and settings you cannot decipre on the road compared to a dyno. (Of course the operator and tuner needs to know what he´s doing, and know how to work with vintage engines and carbs)
If you are alright with 95% of an engines potential, the O2 sensor alone can be considered as "OK". I´m not talking WOT performance alone. That´s relatively easy. The lower to mid rpm behaviure is where we often find the most. On the other hand, sometimes the perfect setting developed on the Dyno does not work on the street. (Which is why any dyno session should be finalized with a test drive) In such cases you may need to go to a slightly richer setting on cruise or a little more acc pump squirt- or a little less. A couple of years ago I had just such a situation with a BB512 which had a very annoying stumble on tip in between 1800 and 2100 rpm. Turned out that the distributor advanced too much in that area foir what the engine wanted. Took me a full afternoon to figure that out.
I was sincerly hoping that Paul & Luke would go a little outside the box with this test, but so far most if not all was predicatble. That said, we know the theoretical power potential of the cylinderheads on that engine, but we don´t know the port flow quality. That´s always a joker. Lets hope the last round reveals something new.
I do agree with Paul wrt the swap to the FK10. That probably doesnt do any good except pulling more rpm power over the curve. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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UK Luke 72 Samba Member
Joined: September 07, 2011 Posts: 2867 Location: Little Britain
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Posted: Tue May 24, 2022 2:31 pm Post subject: Re: Sidewinder 'Dip' |
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k@rlos wrote: |
UK Luke 72 wrote: |
k@rlos wrote: |
I’ve got an A1 1 5/8” sidewinder with a twin tube muffler or race bullet depending on my mood 😅 and I’ve never had this dip either. |
You'd never know without it on a dyno. |
I’ve had it on the dyno.
[url=https://postimg.cc/jDrqtpk7][img]https://i.postimg.cc/rwDDCc1Q/DA89719-A-A49-C-4846-B766-48-C4637-AEBE6.jpg[/img
I do take dynos with a pinch of salt though as I could take it a different dyno the next day and make 10hp more or 20hp less. Used it as a tool to get the AFR dialled in, now I’ve got a wideband so won’t ever bother with a rolling road again. |
Apologies, I thought you had said somewhere it was never on a dyno.
The thing I have found with dyno time is that you can load the engine in ways that are very difficult out on the road, cutting tuning time massively. _________________ 2276 Beetle build https://www.thesamba.com/vw/forum/viewtopic.php?t=670744&highlight=2276+beetle+daily
2276 EFI Conversion https://www.thesamba.com/vw/forum/viewtopic.php?t=689172 |
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Rafo67PE Samba Member
Joined: September 25, 2019 Posts: 42 Location: Lma
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Posted: Tue May 24, 2022 5:19 pm Post subject: Re: Sidewinder 'Dip' |
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k@rlos wrote: |
I’ve got an A1 1 5/8” sidewinder with a twin tube muffler or race bullet depending on my mood 😅 and I’ve never had this dip either. |
I have an A1 1 5/8 with twin tube too ... What is the biggest difference with the race bullet? |
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k@rlos Samba Member
Joined: October 04, 2012 Posts: 485 Location: Suffolk, England
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Posted: Tue May 24, 2022 10:57 pm Post subject: Re: Sidewinder 'Dip' |
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Rafo67PE wrote: |
k@rlos wrote: |
I’ve got an A1 1 5/8” sidewinder with a twin tube muffler or race bullet depending on my mood 😅 and I’ve never had this dip either. |
I have an A1 1 5/8 with twin tube too ... What is the biggest difference with the race bullet? |
It’s noisy as hell! I only use it when I’m running it up the strip, like a stinger if you will |
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Paul.H Samba Member
Joined: April 03, 2015 Posts: 613 Location: England
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Posted: Wed May 25, 2022 1:04 am Post subject: Re: Sidewinder 'Dip' |
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k@rlos wrote: |
UK Luke 72 wrote: |
k@rlos wrote: |
I’ve got an A1 1 5/8” sidewinder with a twin tube muffler or race bullet depending on my mood 😅 and I’ve never had this dip either. |
You'd never know without it on a dyno. |
I’ve had it on the dyno.
I do take dynos with a pinch of salt though as I could take it a different dyno the next day and make 10hp more or 20hp less. Used it as a tool to get the AFR dialled in, now I’ve got a wideband so won’t ever bother with a rolling road again. |
Very nice but without a dyno graph you might as well post a pic of it parked outside the local kebab house |
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k@rlos Samba Member
Joined: October 04, 2012 Posts: 485 Location: Suffolk, England
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Posted: Wed May 25, 2022 9:18 am Post subject: Re: Sidewinder 'Dip' |
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Paul.H wrote: |
k@rlos wrote: |
UK Luke 72 wrote: |
k@rlos wrote: |
I’ve got an A1 1 5/8” sidewinder with a twin tube muffler or race bullet depending on my mood 😅 and I’ve never had this dip either. |
You'd never know without it on a dyno. |
I’ve had it on the dyno.
I do take dynos with a pinch of salt though as I could take it a different dyno the next day and make 10hp more or 20hp less. Used it as a tool to get the AFR dialled in, now I’ve got a wideband so won’t ever bother with a rolling road again. |
Very nice but without a dyno graph you might as well post a pic of it parked outside the local kebab house |
🤷🏻 |
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UK Luke 72 Samba Member
Joined: September 07, 2011 Posts: 2867 Location: Little Britain
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Posted: Wed May 25, 2022 10:16 am Post subject: Re: Sidewinder 'Dip' |
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Torben what we're you hoping to see?
As outlined all along, this was about finding out how the engine responded to 36mm, 38mm, 40mm and 45mm throttle bodies and leaving with the best size to suit this engine.
The sidewinder chat has somewhat skewed our tests but as we said, we will only spend time to see if we can tune that out once we have finalised the setup. The plenum chambers, the comically long stacks, filters etc are all just playing about with the parts we have on hand.
The confusion came from here.
k@rlos wrote: |
I don’t know if there is a dip as I’ve never had on a dyno. I do all my tuning with a wideband, but it feels like my motor pulls clean and hard from idle to 7000rpm. |
_________________ 2276 Beetle build https://www.thesamba.com/vw/forum/viewtopic.php?t=670744&highlight=2276+beetle+daily
2276 EFI Conversion https://www.thesamba.com/vw/forum/viewtopic.php?t=689172 |
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k@rlos Samba Member
Joined: October 04, 2012 Posts: 485 Location: Suffolk, England
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Posted: Wed May 25, 2022 10:26 am Post subject: Re: Sidewinder 'Dip' |
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UK Luke 72 wrote: |
Torben what we're you hoping to see?
As outlined all along, this was about finding out how the engine responded to 36mm, 38mm, 40mm and 45mm throttle bodies and leaving with the best size to suit this engine.
The sidewinder chat has somewhat skewed our tests but as we said, we will only spend time to see if we can tune that out once we have finalised the setup. The plenum chambers, the comically long stacks, filters etc are all just playing about with the parts we have on hand.
The confusion came from here.
k@rlos wrote: |
I don’t know if there is a dip as I’ve never had on a dyno. I do all my tuning with a wideband, but it feels like my motor pulls clean and hard from idle to 7000rpm. |
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Ok I’ve been pretty unclear here 😂 Different engine, had a 2110 with the sidewinder on a dyno. New engine (2276) has never been on the dyno and neevr will be as I now have the wideband. The pic in the cell is pretty old. |
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Paul.H Samba Member
Joined: April 03, 2015 Posts: 613 Location: England
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Posted: Wed May 25, 2022 11:31 am Post subject: Re: Sidewinder 'Dip' |
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🤷🏻
Now we're talking I have to drive 30 miles to get a decent kebab |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7215 Location: Videbaek Denmark
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Posted: Wed May 25, 2022 11:46 am Post subject: Re: Sidewinder 'Dip' |
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UK Luke 72 wrote: |
Torben what we're you hoping to see?
As outlined all along, this was about finding out how the engine responded to 36mm, 38mm, 40mm and 45mm throttle bodies and leaving with the best size to suit this engine.
The sidewinder chat has somewhat skewed our tests but as we said, we will only spend time to see if we can tune that out once we have finalised the setup. The plenum chambers, the comically long stacks, filters etc are all just playing about with the parts we have on hand.
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Fair enough. I thought you would go further into correcting the collector/muffler for the engine. The ITB size was sort of a no brainer for me. Wth that displacement I would choose the 40 mm for best overall power and tunability. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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UK Luke 72 Samba Member
Joined: September 07, 2011 Posts: 2867 Location: Little Britain
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Posted: Wed May 25, 2022 11:50 am Post subject: Re: Sidewinder 'Dip' |
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Alstrup wrote: |
UK Luke 72 wrote: |
Torben what we're you hoping to see?
As outlined all along, this was about finding out how the engine responded to 36mm, 38mm, 40mm and 45mm throttle bodies and leaving with the best size to suit this engine.
The sidewinder chat has somewhat skewed our tests but as we said, we will only spend time to see if we can tune that out once we have finalised the setup. The plenum chambers, the comically long stacks, filters etc are all just playing about with the parts we have on hand.
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Fair enough. I thought you would go further into correcting the collector/muffler for the engine. The ITB size was sort of a no brainer for me. Wth that displacement I would choose the 40 mm for best overall power and tunability. |
It's pointless looking at the dip though until we have decided on which induction we're going with I think.
I'll need another cylinder of Argon before I can start playing with modding the muffler too. _________________ 2276 Beetle build https://www.thesamba.com/vw/forum/viewtopic.php?t=670744&highlight=2276+beetle+daily
2276 EFI Conversion https://www.thesamba.com/vw/forum/viewtopic.php?t=689172 |
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Paul.H Samba Member
Joined: April 03, 2015 Posts: 613 Location: England
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Posted: Wed May 25, 2022 12:11 pm Post subject: Re: Sidewinder 'Dip' |
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I thought we already ruled out the header as the main cause of the dip ?
I got another engine on the dyno at the moment that had a low wave in the curve, fitted with a standard 1 5/8 merged header with the 3 inch extractor pipe - Is it the header ? No It just tuned out with timing |
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7215 Location: Videbaek Denmark
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Posted: Wed May 25, 2022 2:20 pm Post subject: Re: Sidewinder 'Dip' |
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- That is correct Luke.
- You can do a lot with programmable ignition and fuel, but not all. With carbs (as most around here runs) you already take one thing away to fine tune with. Sidewinders are always down on power compared to out the back headers, especially as cam duration increases due to the simple fact of shorter primaries and often a better layout of the tubing. But working with the collector and muffler position (and muffler type)can make quite a bit of difference, to the point of increasing power over a stub or an open header.
This is also why I mentioned at some point that almost all headersn´mufflers for ACVW´s are made wrong. One of the few that works very very well is the Wasp. Not just because of the step header, but also due to the collector and muffler being much more right. BUT, mainly for agressive engines of course. Anything sub 180 hp and it is mostly a waste of money. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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UK Luke 72 Samba Member
Joined: September 07, 2011 Posts: 2867 Location: Little Britain
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Alstrup Samba Member
Joined: July 12, 2007 Posts: 7215 Location: Videbaek Denmark
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Posted: Wed May 25, 2022 3:23 pm Post subject: Re: Sidewinder 'Dip' |
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Thats part of it, and the design, or layout of the muffler.
Don´t get me wrong. It is not "perfect", but its darn close, and about as good as can be within the limits of a street legal muffler. _________________ https://www.thesamba.com/vw/forum/viewtopic.php?t=435993 |
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modok Samba Member
Joined: October 30, 2009 Posts: 26787 Location: Colorado Springs
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Posted: Wed May 25, 2022 5:37 pm Post subject: Re: Sidewinder 'Dip' |
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Wobbles in the torque curve are a result of the harmonic behavior of the intake and exhaust manifolds.
In particular the intake port pressure compared to the exhaust port pressure during the valve overlap period is where a lot of magic happens.
Obviously that will depend on what BOTH sides are doing.
It is typical that a type-1 engine with relatively high flowing heads and an aggressive cam + long tube header... the exhaust side will function poorly in the 3600 & 2200 rpm area no matter if there is a dip in the torque curve or not. I could talk for many pages about it, but don't want to bogart the thread if the how and why of that isn't what you want to know. |
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Rafo67PE Samba Member
Joined: September 25, 2019 Posts: 42 Location: Lma
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Posted: Wed May 25, 2022 6:16 pm Post subject: Re: Sidewinder 'Dip' |
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k@rlos wrote: |
Rafo67PE wrote: |
k@rlos wrote: |
I’ve got an A1 1 5/8” sidewinder with a twin tube muffler or race bullet depending on my mood 😅 and I’ve never had this dip either. |
I have an A1 1 5/8 with twin tube too ... What is the biggest difference with the race bullet? |
It’s noisy as hell! I only use it when I’m running it up the strip, like a stinger if you will |
i will order one |
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Paul.H Samba Member
Joined: April 03, 2015 Posts: 613 Location: England
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Posted: Wed May 25, 2022 10:35 pm Post subject: Re: Sidewinder 'Dip' |
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modok wrote: |
Wobbles in the torque curve are a result of the harmonic behavior of the intake and exhaust manifolds.
In particular the intake port pressure compared to the exhaust port pressure during the valve overlap period is where a lot of magic happens.
Obviously that will depend on what BOTH sides are doing.
It is typical that a type-1 engine with relatively high flowing heads and an aggressive cam + long tube header... the exhaust side will function poorly in the 3600 & 2200 rpm area no matter if there is a dip in the torque curve or not. I could talk for many pages about it, but don't want to bogart the thread if the how and why of that isn't what you want to know. |
Appreciate your inputs on exhaust design but unfortunately we're stuck with what is available that fits the vehicle and has acceptable noise limits. On the induction side of things I've got plenty to play with and it's quick and easy to change and test. We already got rid of the dip and any other gains will come from merely reducing the resistance to flow at the top end.
There is no magical mystery part that will suddenly produce a big power hike |
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UK Luke 72 Samba Member
Joined: September 07, 2011 Posts: 2867 Location: Little Britain
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Posted: Fri Sep 23, 2022 10:00 am Post subject: Re: Sidewinder 'Dip' |
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I'm going to make a new muffler for my system.
Keeping the 1 5/8" sidewinder ideally. 2 silencers probably and if possible, exiting out of the stock cutouts.
Peak power would be nice to maintain but I'd rather focus on making it a proper driver
I've been reading up on theory, as always though it's primarily V8 stuff and probably completely irrelevant to a flat 4...
So I'm all ears, if we're going experimental I'll use mild steel, if we can agree on a design backed by pipe max or some fancy maths then I'm happy to use 304. _________________ 2276 Beetle build https://www.thesamba.com/vw/forum/viewtopic.php?t=670744&highlight=2276+beetle+daily
2276 EFI Conversion https://www.thesamba.com/vw/forum/viewtopic.php?t=689172 |
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Mavelotta Samba Member
Joined: March 27, 2006 Posts: 50 Location: Monroe, Wa.
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