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UK Luke 72
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Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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modok
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Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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 Posted: Thu May 12, 2022 6:16 pm Post subject: Re: Sidewinder 'Dip' |
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| modok wrote: |
If it was just a different intake length it would have shifted the swings, but it smoothed it out, so you must be dampening the intake pulsations with the airbox.
The intake and exhaust tune very different but both have swings like that.
Your test DOES prove that the intake is causing that primarily, but....
Still can be made far better or worse depending on how the intake and exhaust tuning "lines up" through the rpm range.
Calvin Elston once said about intake and exhaust manifolds, tri-y VS four into one, IR VS plenum intakes... that you "Need a plenum on one side or the other" to smooth the pulsaitions and I don't necessarily agree but it is very interesting idea indeed. |
Thought of something funny right after I posted that.
My latest exhaust design does have an added volume at the final collector, so..... that's irony. |
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Paul.H
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Joined: April 03, 2015
Posts: 613
Location: England
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| Posted: Thu May 12, 2022 10:58 pm Post subject: Re: Sidewinder 'Dip' |
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| We'll just keep throwing different parts at it. So far it's had 4 different size throttles with predictable results , small incremental increases at the top end and next we're onto a manifold change |
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UK Luke 72
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Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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Alstrup
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Joined: July 12, 2007
Posts: 7215
Location: Videbaek Denmark
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| Posted: Sun May 15, 2022 3:22 am Post subject: Re: Sidewinder 'Dip' |
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| modok wrote: |
| modok wrote: |
If it was just a different intake length it would have shifted the swings, but it smoothed it out, so you must be dampening the intake pulsations with the airbox.
The intake and exhaust tune very different but both have swings like that.
Your test DOES prove that the intake is causing that primarily, but....
Still can be made far better or worse depending on how the intake and exhaust tuning "lines up" through the rpm range.
Calvin Elston once said about intake and exhaust manifolds, tri-y VS four into one, IR VS plenum intakes... that you "Need a plenum on one side or the other" to smooth the pulsaitions and I don't necessarily agree but it is very interesting idea indeed. |
Thought of something funny right after I posted that.
My latest exhaust design does have an added volume at the final collector, so..... that's irony. |
It is correct. Take a look at a power curve from most any engine equipped with say Kadrons or stocker plus engines. They hardly ever have the dip if the cams are within reason.
| UK Luke 72 wrote: |
Ever since we took the muffler off, and connected it up to dyno extraction system, we have had a large volume collector. Paul will confirm but it's something like 3" dia connected to the header.
Should that have done something to the dip? |
Opening to "free air" right after the collector, which is basicly what you do if the suction is 3", will skew the results quite a bit actually, Mostly in the lmidrange, but also a little on peak power.
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Last edited by Alstrup on Sun May 15, 2022 6:09 am; edited 1 time in total |
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oprn
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Joined: November 13, 2016
Posts: 12730
Location: Western Canada
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| Posted: Sun May 15, 2022 4:16 am Post subject: Re: Sidewinder 'Dip' |
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Modoc, you mentioned earlier about getting the proportions different by going over the top af the engine. That is what I did on this one. What I was really after was a tee pee style exhaust for off road clearance but with the tri Y low end advantage. Then by default, trying to fit in a larger quieter muffler I ended up with a long tube after the second Y. There just wasn't room to get that big muffler closer to the last Y. The end result is the primaries and secondaries are about equal in length and the third tube before the muffler is about 3 times that length.
Not a lot of science in this system, more convenience but I wish there was a dyno somewhere nearby so I could graph the results. Just interested in the curve more that the actual numbers to see if I accomplished the low and mid range that I was after. The butt dyno says so but that is not that accurate.
This one shows the additional length and muffler I added. The first muffler was creating too much back pressure at full throttle.
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Paul.H
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Joined: April 03, 2015
Posts: 613
Location: England
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| Posted: Mon May 16, 2022 1:56 am Post subject: Re: Sidewinder 'Dip' |
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Once we've completed the intake testing I've go a couple of header muffler combos to put on there and I might even have a stinger. It's going to be like engine testing episode of "Myth Busters" a refreshing change from the "Dysney Channel"  |
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rayjay
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Joined: March 26, 2008
Posts: 1506
Location: Buford GA
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| Posted: Mon May 16, 2022 3:12 am Post subject: Re: Sidewinder 'Dip' |
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| oprn wrote: |
| ... but I wish there was a dyno somewhere nearby so I could graph the results.[/img] |
I have been looking for a stand alone G meter performance measuring tool but haven't found an affordable one yet.
A long hill and a stopwatch will document changes but no way to convert to hp/tq |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12730
Location: Western Canada
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| Posted: Mon May 16, 2022 3:57 am Post subject: Re: Sidewinder 'Dip' |
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Far too late to get any "before" data! And beside that a timed run is more an indication of top end power, not so much an indicator of low and mid range improvement. I suppose if the rpms were limited to 3000 it would mean something...
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modok
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Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Mon May 16, 2022 7:37 pm Post subject: Re: Sidewinder 'Dip' |
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No idea if it's ideally tuned, but far as I know should be decent.
Thanks for building it....worth it for the pics, just to prove it can be built. |
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oprn
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Joined: November 13, 2016
Posts: 12730
Location: Western Canada
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| Posted: Tue May 17, 2022 4:19 am Post subject: Re: Sidewinder 'Dip' |
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It feels pretty lively for a 1641 single port but then it's in a light car...
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Tue May 17, 2022 8:38 am Post subject: Re: Sidewinder 'Dip' |
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IMHO the tubing after the collector is too big.slowing the gasses and letting the pulses stagnate and "get confused" dancing around in the big pipe loosing velocity &direction witch will affect scavenging. eye wood try 2" from the collector to the muff. you could make it sleaveable and test lengths to find the place where it needs steped back up to muffler size.. also varrying the 2" dia wouldent be expensive to test other size's the see just what worked best. if you have programable timing you may also be able to do some timing work to complement it. also.put some gaskets on the booster vents and the stacks. and if the boosters are not straight as many arnt, you can fix then now too., rejet as necessary. but remember all engines have dips&highs your trying to minamixe them and maximize the ENTIRE package.
if you have ever watched a fighter jet and seen the flame out the back it will varry in length and how close to the after burner it is at differnt speed&thrust. you can also see different rings in the flame moving,our exhaust is dam neer the same.  they go in waves.and when the waves are in the rong place in the rong pipe....you get a wonkey scavenge. the header is a fixed length on most of these cars so thats not adjustable but after where all the scavagning is taking place is. usualy a cone after the collector cone helps, but how big it gets is what your tuning with as well as length of cone & the pipe comming off it and its lenght&dia. I have a set fo extreamly expensive adjustable stahl headers hear they have 2,4,6,9" "tunable changeable" sections , slip joints for fine tuning different cams shaft,engine size ,intake length whatever. so you can tune and maxamize your combo. sorry no there not for a vw.there for a 67 vette nhra class drag car 287 ci 5 speed zinger. |
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modok
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Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Tue May 17, 2022 4:52 pm Post subject: Re: Sidewinder 'Dip' |
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I suspect the same but it should be tested to prove it.
EYE wood try 2 1/8, but there MAY be some reason it is how it is, that isn't clear. |
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Dauz
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Joined: January 05, 2010
Posts: 1790
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| Posted: Tue May 17, 2022 4:59 pm Post subject: Re: Sidewinder 'Dip' |
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| Anyone not a fan of the AA sidewinder? I have one in the garage ceramic coated. Never used it. 1 5/8 |
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Dauz
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Joined: January 05, 2010
Posts: 1790
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| Posted: Thu May 19, 2022 12:13 pm Post subject: Re: Sidewinder 'Dip' |
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| So no complaints on the AA? There are ZERO traditional merged systems available anywhere. I guess I'll use it. |
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Shane Tuttle
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Joined: February 02, 2011
Posts: 173
Location: Arlee, Montana
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| Posted: Thu May 19, 2022 1:46 pm Post subject: Re: Sidewinder 'Dip' |
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| My CSP Python JUST showed up at my doorstep. After inspecting their work, I would spend the extra money on the Python instead of AA's Sidewinder. Hell, after seeing A1 seemingly slip in QC, I would still go with CSP. They have it in stock. Just need to wait a bit for shipping/customs. |
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Paul.H
Samba Member
Joined: April 03, 2015
Posts: 613
Location: England
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| Posted: Thu May 19, 2022 2:32 pm Post subject: Re: Sidewinder 'Dip' |
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| The quality of the CSP python ain't that great and it's well over priced. Don't know about the A1 and the mufflers on the chinese systems are total crap |
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Brian_e
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Joined: July 28, 2009
Posts: 3290
Location: Rapid City, SD
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| Posted: Thu May 19, 2022 3:20 pm Post subject: Re: Sidewinder 'Dip' |
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I have never held a CSP, but the price seems crazy, especially getting one here in the US. The A1 is absolutely not amazing, especially for the money and the wait. I know CB quit selling them a while back also. They do fit decent, but the mufflers are nothing fantastic.
The AA header is great for the money, but the muffler is junk. The header is typical build and welds. Similar to what the CB house brand looks like. I have had a mild steel AA 1 5/8" sidewinder on my lowered bay for 25k miles now. Driven mostly year round (in South Dakota snow and crap roads), and it is still holding up great. I sandblasted it when it was new, and painted it with BBQ paint. I built my own muffler section with a Hooker brand Super quiet straight through muffler.
I think this "dip" is greatly caused by the sidewinder itself. I have seen it on multiple different engines I have built, and seen it on other guys with sidewinders. Most every one will go super rich in the 2000-3500 rpm range killing power and making it bog. I have been trying forever to jet around it, but I cant get it to work out in my favor. A very similar engine with a standard merge, or a vintage speed doesn't have the super rich spot.
My own sweep the floor 1835cc w/DCNF's had the super rich spot with a AA 1 1/2" sidewinder. I swapped to a CB hideout, and the rich spot went away, and the jetting went back to normal.
I am a fan of vintage speed mufflers for the 145hp and down guys. Good build quality, good fit, quiet, and so far, no odd tuning.
Brian
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Paul.H
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Joined: April 03, 2015
Posts: 613
Location: England
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| Posted: Thu May 19, 2022 11:45 pm Post subject: Re: Sidewinder 'Dip' |
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| Brian_e wrote: |
I think this "dip" is greatly caused by the sidewinder itself. I have seen it on multiple different engines I have built, and seen it on other guys with sidewinders. Most every one will go super rich in the 2000-3500 rpm range killing power and making it bog. I have been trying forever to jet around it, but I cant get it to work out in my favor. A very similar engine with a standard merge, or a vintage speed doesn't have the super rich spot.
My own sweep the floor 1835cc w/DCNF's had the super rich spot with a AA 1 1/2" sidewinder. I swapped to a CB hideout, and the rich spot went away, and the jetting went back to normal.
I am a fan of vintage speed mufflers for the 145hp and down guys. Good build quality, good fit, quiet, and so far, no odd tuning.
Brian |
I think these dips are just a symptom of people over camming the engines
or maybe cheap poor quality chinese mufflers
This engine had a sidewinder and was slightly over cammed with a C35
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Brian_e
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Joined: July 28, 2009
Posts: 3290
Location: Rapid City, SD
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| Posted: Fri May 20, 2022 7:15 am Post subject: Re: Sidewinder 'Dip' |
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| Paul.H wrote: |
I think these dips are just a symptom of people over camming the engines
or maybe cheap poor quality chinese mufflers |
Maybe, but I am running only a [email protected] cam in a 2332cc, and I replaced the China muffler with something pretty decent. 🤷🏼♂️ Mine still has the big dip in AFR.
I really don’t know what it is, and I don’t have the time to get the dyno running and spend a week trying to figure it out right now. I do know it has happened on most all the engines I have worked with, and the only real common thing is the sidewinder.
I am really interested to see what you guys get figured out. 👍🏻
Brian
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