Manx Sidewinder 1-1/2 or 1-5/8 for 1600 with dual IDF 40s?

vincent9993

I always frowned at having a none symetrical exhaust but can no longer live with the ugly and poor performance of my 4-Tip GT style. I had always hoped to be able to modify/rebuild that muffler to larger dimension and shorten the tips (so they don't stick out that far) but let's be honest, I'll never get around to that.

So I'm finally comming to reason and will most probably for sure almost defiantly (lol) order a Manx Sidewinder exhaust. I noticed they have both a 1-1/2 and a 1-5/8 listed on the online store.

I assume I want the 1-1/2 version but before I order the wrong one, I though I'd ask. I did try to search but there are 1,000s of Sidewinder posts and the few I read did not yield any help in choosing.

TIA.

nightmanx11 · Posted: Tue Jul 12, 2011 3:30 pm Post subject:

vincent9993 · Posted: Tue Jul 12, 2011 3:35 pm Post subject:

Thanks Joe!

LouisB · Posted: Tue Jul 12, 2011 4:30 pm Post subject:

My vote is for t he 1.5 as well.

--louis
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'67 Manx II

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lostinbaja · Posted: Tue Jul 12, 2011 5:49 pm Post subject:

1 1/2" all the way....
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Glenn · Posted: Tue Jul 12, 2011 5:50 pm Post subject:

1-5/8" is way too big.

1-3/8" would be best.
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jsturtlebuggy · Posted: Tue Jul 12, 2011 9:43 pm Post subject:

Glenn,
Yes a 1 3/8in would be better for a 1600cc except the Sidewinder only come in 1 1/2 & 1 5/8in.
The 1 1/2 is the one they sell the most of.
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BL3Manx · Posted: Wed Jul 13, 2011 12:08 am Post subject:

lostinbaja · Posted: Wed Jul 13, 2011 6:15 am Post subject:

Seeing that Vincent's buggy sees a lot of long road trips I think the 1 1/2" would still be the best choice even if the 1 3/8" was available.

Image may have been reduced in size. Click image to view fullscreen.

At that kind of RPM the 1 1/2" header would be helping.
_________________
Jerry...
If it's being towed, it must be a trailer!
"Vee Grow Too Soon Oldt Und Too Late Schmardt"
RIP Morgan

My photos
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BL3Manx · Posted: Wed Jul 13, 2011 8:38 am Post subject:

lostinbaja · Posted: Wed Jul 13, 2011 8:45 am Post subject:

I would bet that they were not running 3700 rpm for an extended amount of time. A dyno pull takes all of 20 seconds.
No real way to tell without putting Vincent's engine on the dyno and running it at highway speeds.
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Jerry...
If it's being towed, it must be a trailer!
"Vee Grow Too Soon Oldt Und Too Late Schmardt"
RIP Morgan

My photos
http://www.manxgallery.org/gallery/album92

BL3Manx · Posted: Wed Jul 13, 2011 8:53 am Post subject:

You're right, there's no way of knowing until you test it, but when they built the engine they went to the professionals and asked for their best recommendations. They recommended the 1 3/8" header and it didn't disappoint, it impressed the hell out of them on the dyno. On the road they got just shy of 35 mpg at 65 mph.

http://www.cbperformance.com/Sep2007.asp

The size of the header has to match the characteristics of the engine. Too small will cause back pressure. Too big will reduce velocity and scavenging.

jsturtlebuggy · Posted: Wed Jul 13, 2011 9:35 am Post subject:

Vincent is using dual IDF carbs on his engine, making it breath better than with a stock carb.
There may be some kind of results someone has found with using these carbs and the two different sizes of exhaust.
_________________
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Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

lostinbaja · Posted: Wed Jul 13, 2011 9:46 am Post subject:

BL3Manx · Posted: Wed Jul 13, 2011 10:04 am Post subject:

Really nothing to do with header diameter but the results I thought most dramatic was comparing performance with ignition timing at 28 BTDC and 32 BTDC. As expected it increased power but it also increased mileage and lowered the oil and head temps. Until I see something better, I'm using 32 degrees.

http://www.cbperformance.com/Sep2007.asp

vincent9993 · Posted: Wed Jul 13, 2011 10:18 am Post subject:

Thanks for all the replies folks. I kind of feel bad having started this topic in this forum and not in the Engine forum but felt it was more specific to my Buggy configuration and I wanted advise on the Sidewinder specificaly for the FG buggy.

I was not looking for a heated debate on the advantage of 1-3/8 over 1-1/2. The Manx Sidewinder is not offered in 1-3/8 so the closest I can get to that is 1.5. I appreciate the supporting reference demonstrating the 1-3/8 having better (or potentially) better performance but it's not an option I can consider at this time.

Now I do have to ask, all these years everyone has been telling me to get rid of the 4-tip GT muffler saying it was too restrictive and going with a free flow (or better flowing exhaust) would improve performance, and here we are discussing more restriction (more than 1.5 at least) being better (both on HP & TQ and consumption). Is everyone just messing with me or am I misunderstanding the message? Perhaps the 4-Tip GT is more restrictive than the 1-3/8?

It's almost making me reconsider keeping my 4-Tip GT and just mod it to fit better beneath the bumper.

In anycase, if I do decide to go with the Manx Sidewinder, I'll be going with the 1.5".

Thanks for all the feedback. Believe it or not, it helped. Wink

Lo Cash John · Posted: Wed Jul 13, 2011 10:29 am Post subject:

I guess 1.5" is the best choice but still to big. I guess once you buy that you've got no choice but to build a bigger motor! Smile

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LouisB · Posted: Wed Jul 13, 2011 10:56 am Post subject:

The sidewinder from the Meyers is a true merged header and will flow better than the 4 tip. The four tip is a very restrictive design and can actually hurt your performance. You do need a certain amount of back pressure to help with low end torque but not so much that the air can't get out of the engine.

Air goes in the engine, air has to get out of the engine. Too little of a pipe causes the exhaust to back up and not be able to get out of the engine. The engine will also run hotter. As the exhaust exits the engine it helps to pull more air into the engine by creating a vacuum. Too big of a pipe and the exhaust looses velocity and doesn't help pull more air into the engine.

You have to think of an engine in terms of individual components but as a system that works together. Each part has to be sized so that it will work with every other part and either not create to much of a restriction in the air flow or cause a loss of velocity in the air flow.

I would suggest you get a copy of the VW Interchange Manual and the VW Beetle Performance handbook. Both of these have excellent information that may help with some of your questions.

http://www.amazon.com/Beetle-Performance-Handbook-Step-Step/dp/0760304696

http://www.amazon.com/Aircooled-Engine-Interchange-Manual-Aftermarket/dp/0760303142/ref=pd_sim_b_3

For a stock engine with no modifications to the heads and 40 IDFs I would run the 1.5 header. I would also make sure you have 28 vents in the IDFs. The bottle neck in this combination will be the unported heads and the stock cam. You would pick up noticeable power with some mild port work and a three angle valve job on the stock valves.

Hopefully I didn't just confuse you more.

--louis
_________________
Louis Brooks
'67 Manx II

Old people at weddings always poke me and say "Your next." So, I started doing the same to them at funerals.

jsturtlebuggy · Posted: Wed Jul 13, 2011 11:00 am Post subject:

Vincent,
The TriMil Bobtail with quietpack muffler is also a good exhaust.
Not knowing what kind of sound restrictions you have in your area the Manx Sidewinder may be to much noise.
I know from my own experience with a Sidewinder that after awhile the glasspack droning gave me a headache. With my Sidewinder it has the mounting flange between the muffler and header. The new ones don't.
I tried several different mufflers now and even install a SuperTrapp on the glasspack in seach of relief.
What I have on there now is a HushPower made by FlowMaster. Changing to different mufflers is not cheap. That is why I am suggesting a different exhaust system to use.
You drive long distances and noise from a loud exhaust can make it uncomfortable.

_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

MURZI · Posted: Wed Jul 13, 2011 11:04 am Post subject:

Put a tri mill thing exhaust on that thing. Kevin at Mendola installed one on one of the manxters and it looked cool. They sound throaty too!!

And...... I have the euro tri mil on my stock headed, 40idf fed, 1600. Runs like a champ......second gear rubber. It's 1.5" and the only ones that hate it or the guys with 1776's and 1835's that have just got their doors blown off by it..... Laughing

The baja/ hayabusa setup I have on the baja is easy to do and very, very, very quiet.

On a 1600 I think you are splitting hairs with any exhaust you install on it. 1 3/8 would be best...merged, 1.5 not bad at all, 1 5/8......uh NO.

In my not so humble opinion.
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Manx Sidewinder 1-1/2 or 1-5/8 for 1600 with dual IDF 40s?
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