Exhaust option for my lowered CMC

You would have to completely cut up that mid-engine spyder exhaust system to do anything with it. There's no point in buying one and doing that. You would be better off having an exhaust shop make one that fits your car from scratch as it would be less work.

 

If you want a center exhaust tip, I'd recommend getting one of these headers (no heater boxes though): http://vwparts.aircooled.net/A...w112-sw158-sw134.htm and the matching center exit muffler: http://vwparts.aircooled.net/A...Exit-p/a-1-swctr.htm

 

That exhaust doesn't hang any lower than the oil sump on your engine.

Ok. I may just order the header and have my shop do the rest.

I see slip-on j-pipe from the link for the header. Any difference/benefit between slip-on vs. flanged j-pipes?

Just be aware that the matching A-1 muffler has a shaped inlet to work with the collector and for performance reasons. The muffler core is also sized to match for tuning purposes. I don't know how good your shop is but some might not take into account those engineering considerations.

Scott,

 

I've built no less than 5 exhausts off A1 sidewinders. There's nothing magic about what Tiger does from the collector back-- but what your shop will find is that there are precious few places to actually put a muffler besides where Tiger does. His muffler is pretty nice as well.

 

As Jusin implied: exhaust tuning is a bit of a science. I've read a fair bit about it, and there are charts which give you ideal lengths, etc., but they kind've go out the window with the narrow collector Tiger puts on the header. This is deliberate, and so that you can do pretty much what you want after the header.

 

FWIW, the tube lengths on the sidewinder vary up to 6". It's harsh, but it is what it is- nothing is perfect. Anybody's Merge header is true equal-length, and the tubes are the right length for your engine-- but the collector points straight back. If you want a true equal-length sidewinder, CSPs Python is.... for about 3x the money. I've done a merge exhaust with "perfect" primaries, and I couldn't tell any difference on the dyno or the street.

 

For a DTM, the slip-on system would work great, and it's a lot less money. The only reason to do the flanged J-pipes is so you can run sled tins and a thermostat. You aren't going to do that, so the non-flanged (slip-on) set-up is actually better.

 

With the exhausts I've done, one option I've tried which worked well (until I changed some things that made it impossible) was to wrap the exhaust completely around the engine and put 2 mufflers in series, one beside each valve-cover. The sound is perfect- the length is pretty important in "mellowing" the tone, but keeping it on a bark when hammered. Short glasspacks would be fine- there's two of them in series after all- and you can do the center exit thing all the kids like so much. If you do this, it's pretty easy to keep the collector as the lowest point on the system. I'd go ahead a grind the rear valance to bring the pipe out just under the bumper, and keep it high enough to not drag on every single driveway.

 

Good luck. You'll spend more than you thought possible. If you can live with it, Tiger's set-up really is the most economical way to go.

One more thing- if you do build one, get a collector flange and transition piece from Tiger. You can't do it correctly without.

But didn't A-1 use magnaflow and dynamax mufflers a while back before they started to make their own brand mufflers? 

 

 

Maybe Peter Taddeo can chime in here, but the shop he referred me to (in Va) installed his A-1 along with upgrading his engine and the fabricator said he had to trash most of the system exhaust system Peter brought because it wouldn't fit his Beck. 

 

The shop itself and the guys there really know their stuff. From exotics, to vintage, to track cars, they work on everything German. 

 

https://plus.google.com/105072816186317371002/posts

Brand doesn't matter, it's what's inside that counts.

Yeah, I wouldn't have any reservations with that type of shop fabbing your exhaust parts.

Ok. I spoke of brand being A-1 now uses their muffler only with the matching you stated. Yet in the past they used/offered other "brand" mufflers (Magnaflow, Dynomax, etc) before they went with their own. Wondering what the difference is now.

Yeah I was impressed with them. They have more stuff on there FB page. 

https://www.facebook.com/imamotorwerke?ref=br_rs

Re. fitting an A1 to a Beck: Only the muffler needs changing and the changes are subtle, but important.  The room between a rear frame rail and the tire is limited and the muffler has to be re-angled to clear both.  The header itself is unchanged.

I've got one sitting here. There's no magic in it- it's a better MagnaFlow, made by Thrush for Tiger. I bought one to build exhaust #5, but I'm thinking of going a different direction. Contact me if you want it- I can send it back, or sell it to you at a bit of a loss to save myself the hassle.

 

As for the stock A1 exhaust not fitting: pan-based VWs are what Tiger built the exhaust around. It's the tube-frame cars that throw some curveballs in for stock exhaust fitment. IMs especially, since Henry actually relocates the engine/transaxle further forward for better weight distribution.

 

Tiger will do anything you want. If you are unconvinced about how it will fit, I'd recommend buying the center-out exhaust complete- but have him ship the muffler totally loose. The exhaust would come in three pieces: the collector and bend, the muffler, and the center-out tail-pipe. You could then have your shop weld it together or modify as needed (it won't need modified) from there.

I'm not saying A-1's muffler's are "magic" or "special". Adding a divergent cone on the collector outlet and picking a muffler core (manufacturer doesn't matter) to match the exhaust pipe flow is simple. But both are important to the overall performance of the system. It's easy to do it wrong by just slapping stuff together and get sub-optimal or even detrimental effects on engine performance.

 

Muffler's are especially easy to get wrong because most manufacturer's use the same oversized core but just weld different size pipes on the inlet and outlet. But only one of those pipe sizes will be properly matched to the core airflow such that it's "invisible" and acts just like another length of pipe for tuning purposes. Too large and the exhaust tuning will act like you simply cut the exhaust off where the muffler inlet is. Too small and you choke off the top end performance.

 

On a front-engined car, this doesn't matter as much. The stock mufflers are typically already oversized for better sound absorbsion and the pipes are long enough that the exhaust's peak RPM change (~2600 rpm to ~3000 rpm) will probably go unnoticed. Plus there could be enough room to add resonator boxes if you really want to be specific about the exhaust tuning. On a VW, you don't have the room for all that. The difference between a properly matched muffler and an oversized one on an A-1 header means changing the secondary pipe length from about 6 feet (fundamental resonance at 4400 RPM) to 1 foot (resonates at 26000 RPM). One of those is a tad more useful to your engine.

Thanks for all the insight Justin. In the end, my real request is to make sure things don't hang to low and have good performance—I'd rather see everything hidden except the exit exhaust(s). On a lot of A-1 pics I've seen on our speedsters, some are lower then others. I may just grab Stans A-1 muffler, get a A-1 header, and see what my shop wants to do.

Unless you cut a notch in the rear valence for the exhaust tip, you may have to reposition the post-muffler pipe a few inches lower so the tip goes below the valence (the speedster specific A-1 muffler may already take this into account, don't know don't have one myself). The header and muffler themselves don't have to be lower.

and they are made well.

FYI,

 

Spoke to Tiger at A-1 in great length about my engine today and he strongly suggested that I stick with a 1 1/2" system. He saw pics of my heads and ported intakes and said it was a mild engine at best—none of the big stuff he normally deals with. Stated the 1 5/8 system I wanted was overkill and would lose some usable lowered torque.

 

My 2110cc Motor --
Genuine Weber 44mm IDF Carburetors 
Match porting & precision balancing.
Aluminum Raised Roof Shuffle Pinned Super Case
76mm Forged One-Piece 4140 Chromoly Crankshaft
5.400" H-Beam Chromoly Super Race Rods
94mm Forged Mahle Pistons 
Total Seal Gapless 2nd Rings
Teflon Wrist Pin Buttons
044 Super Mag Heads -- 40x35.5 Valves
Duel Hi-Rev Valve Springs, CNC Ported w/ Match Port Manifolds
Ceramic-Coated Piston Tops, Valves, Chambers & Exhaust Ports
.060" Copper Head Gaskets
WebCam Camshaft, Grind #163
Duel Thrust Cam Bearings
Scat Lube-A-Lobe Lifters
Chromoly Pushrods
Pauter Billet Roller-Tipped 1.3 Ratio Rocker Assemblies
8mm Chromoly Head Studs
CSP Aluminum O-Ringed Bolt-On Valve Covers
Straight Cut Cam Gears
Crankshaft Racing Spacer
Schadeck 26mm Aluminum Full-Flow Oil Pump
Billet Full-Flow Oil Pump Cover
3.5 Qrt Deep Sump w/ Welded Pickup
Billet Aluminum Sump Plate w/ Magnetic Drain Plug
External Full-Flow Oil Filter and Thermostat Controlled Oil Cooler
Sync-link Throttle Linkage
Vertex Magneto w/ Billet Clamp
DTM-Mount Fan Shroud
Porsche Style Breather Tower
Serpentine Belt Assembly
Polished 55 amp Alternator
Lightened Flywheel
36mm 4130 Chromoly Gland Nut
Kennedy Stage 1 Clutch Package
Rotating Assembly Balanced to Within 1/10 of a Gram / Extremely Smooth
Heads and Deck CC'd to 8.5:1 Compression Ratio

Good call. I've got a 2110 with pretty nice heads- hand ported 40x35. It runs a LOT better with a 1-1/2" sidewinder.

I know Tiger well, I just put in an order for 30 exhaust systems. CB is a dealer for A-1 and his exhaust systems are the best on the market. I would have to disagree on the 1-1/2 exhaust for your engine. The 76x94 engine combo is a high revving combination. From my dyno experience, you are giving up about 8-10 HP by going to the 1-1/2 exhaust over the 1-5/8. I have not seen enough loss in mid range torque on your engine size to justify the smaller exhaust primaries.

   

While Pat is right, it all depends what you want. Yeah, the engine will want to rev, and to use all the higher end power it's capable of, then the 1 5/8" will give that. For a torquier, smoother bottom end midrange (where you drive 95-99% of the time on the street), the 1 1/2", although it will give up a little bit of top end, will be a better fit. The cam/rocker combo will run out of steam at about 6,000rpm and that's also about the limit for the smaller exhaust on a 2110, so it all comes down to how you want to drive the thing.

ALB,

 

That was Tigers point, more usable low-end torque for my set-up. But if Pat is saying the loss is not noticed, then I may call Tiger back.

 

As far as what I want or how I drive—I'm not sure how I'm going to use my speedster. I've only had it since last May and driven just 300 mile on it so far (then fixing, correcting and tinker). I only have a 20 year history or pleasure riding with motorcycle and track times (not a car), so I would probably use my speedster like a 4-wheel motorcycle—minus track days. I would like lower RPM at 70 highway speeds, and enough "punchy" power for torquey backroad runs.

 

I do want the most available horsepower when I want, but not necessary always use it (my 2-wheel thinking). In the past, I never pushed any of the bikes I've owned to their limits (even on track days) because I've never been a professional racer (aspired to be). But it was a great feeling knowing I had all the power on tap.

On the dyno, I see a power and torque gain from 3K rpm and up using the 1-5/8 exhaust over the 1-1/2 on 76x94 engines using close to the same components. The sidewinder primaries are long. My experience is to go up on primaries one size when they get over 32" in length. I believe the sidewinder is about 36" if I remember correctly.

Thanks for the info, Pat.

Yes, thank you Pat.

AND THAT my friends is what makes Pat Downs, Pat Downs. When you've spent your entire life doing this and doing it better than anyone else you speak from authority and experience.