308/328/Mondial performance exhaust development

If I've followed this thread correctly, both of the most recent muffler / resonator setups are predicated upon the use of aftermarket headers only. (i.e., these systems can't be fabricated and used with the stock exhaust manifolds, right?)

 

Yes - Larini s/s headers will be used that are European spec. equal length. I'll have Tate Casey at Carobu look at the collector closely, and modify if neccesary; then plan to ceramic coat the headers inside and out. Will pay special attention at fitting to ensure port/gasket/header matchup, and evaluate any flow interference from the air injector.

The stock manifolds are not too bad, actually - certainly after port matching.

These exhaust systems WILL fit and work fine with the stock headers and muffler hangers.

best
rt

 

Talked to the Jet Hot ceramic coating folks today - their tech guy said that while they do coat mufflers, it has no real performance effect like it does on the headers. He said it did help on heat insulation, rust prevention and appearance. He also said that the coating did not affect the sound.

So the plan now is to coat the headers inside and out, coat the connecting tubes and consider doing the muffler if s/s not available.

Still waiting on the headers to arrive from England...

 

I've been very pleased with my Larini and it looks nice too.

 

Steve - I found the perfect muffler for you for the type K (see post #55) straight out the back from the header option. You can bolt this Magnaflow flow through on directly to the header and run it straight out the back - no muss, no fuss. It's stainless steel and the whole thing would be $600 plus about $100 for installation at a good racing muffler shop.

Here's a whole page of similar sized with different style tips if you want to go oval or square:
http://www.magnaflow.com/02product/shopdisplayproducts.asp?zone=main&id=386

It would sound impressive I'm betting.
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Looks interesting, many thanks! Yeah, my car needs a change. Will seek and decide.

 

After studying the Ferrari muffler systems from the 250 through Daytona, I have picked up that they use 2 or three of the same sized mufflers, probably taking advantage of the dual and even perhaps triple resonance silencing that we have discussed here which gives that sonorous smooth tone.

After pouring over multiple lists of what COTS mufflers are available, I have found a combination that looks like it may fit which gives three matched 14" long silencer boxes to enable resonant silencing. The two main muffler flows are stated to allow 591 hp without loss. While perhaps a little heavier than I'd like, the sound promises to be low and smooth with the flow through design allowing maximum flow.

Another tailpipe option would be to use smaller Ansa resonated tips if the Magnaflow tips (shown below in my last post) had fit problems. If these are used, there should be room to use the two 14" mufflers OR two 20" versions of the same unit.

Besides a slight weight penalty, the other concern is that the flow does a 360 degree turn. I think with this system the loss due to that will be minimized by more gentle bends in the tubing allowed by the smaller 14" boxes.

The goal of this installation was not neccesarily just performance, but the best sound characteristics that would match a daily driver and GT trip car. With the volume of muffler available, three identically sized resonant silencers and identical sized mandrel pipes throughout, this system holds promise for the best sound with excellent flow.

Shown below are photos of Ansa systems from a 250 Lusso and a 330 GTC showing the series of same sized silencers. The last pic is the proposed type L.

All comments welcome - will decide and fab the system in the next weeks - hope it works!
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Here is a much simpler arrangement with where the exhaust sees two 14" silencers effecting the dual resonance silencing, but has a less tortuous path, less total silencer exposure and less resistance (more noise).
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By the looks of your last diagram, Ansa did a pretty good job with what they had to work with. Tubi made it louder, as did others, but it all seems to be the same idea. I have a pdf file of the 308 homologation, and its shows several cut through drawings of the euro muffler. It actually looks rather open, without a lot of baffling, basically looking like the muffler cannister is a large expansion chamber. I have never heard one to be able to make any comment, but the cars reportedly made 255HP with that muffler. I would post it on here, but as I got it from the owners site its probably copywrited. I could try drawing it freehand and see if I can post it, if anyone is interested.

 

Please do. If you feel uncomfortable posting it, I'll pm my email

Many thanks!
Russ

 

I guess if I set down on a table and took my time I could draw this out better, but you get the idea.
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Here are the measurements of the Mondial exhaust bay; should be similar for 308GTB/S and 328 GTB/S

Well after spending some time measuring out the tiny Mondial exhaust bay and mapping frame rails, etc, came up with s/s system that:
true dual flow through exhaust
should have dual resonance noise cancelling from equal silencer length/volume
should fit
not too heavy
allow room for gentle tubing bends (not shown in drawing)
should have a deep low and quiet (relatively) tone that is very smooth
should be a sweet sound at cruise that is non-tiring
only moderately challenging to fabricate
allows for hi-flow cats or small resonators off the headers

Will probably ceramic coat (excepty for chrome tips) for discolration/road wear/heat insulation protection

Again this is based on studying older Ferrari V-12 systems that use similar twin equal sized dual silencers with resonated tips
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Carobu called today and the Larini Euro headers are in. Speaking with Tate Casey at Carobu, he commented that the collectors looked good, and the contructioned looked quite good as well, with the header lengths being a bit better well matched than stock.

Although they look pretty bling in s/s, will ceramic coat for heat insulation (protecting my starter and alternator) in titanium grey.

Have found someone to fab the muffler system, and will ceramic coat it as well in the same color.

Hopefully by sometime in December this winter project will be done.
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Russ,

Sorry to take so long with pictures of my 308 exhaust system. I've been pre-occupied with a zillion other things. I had hoped to give you the sound clip you asked for but I blew out a seal in the plenum under the supercharger and still have not been able to finish that work. Anyway, it looks like you're pretty much settled on a design but here are two views of my "home made" system. I had the stock headers and the intermediary pipe JetHot coated but the rest is 304 stainless. The mufflers and non-resonator tips are magnaflow parts. I no longer have part numbers but the mufflers have 2.5" inlets and outlets and pass the golf ball test easily. I think it sounds great without being too loud and everyone else tells me the same thing.

Wil
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Looks great please post some pictures inside of the collectors.

 

Wil
I really think that is a terrific dual system.
As your usual, it looks beautifully constructed. I initially had planned the exact system with resonated tips, but was afraid it would be too loud on commutes/road trips. How do you compare the volume to a stock or tubi muffler system?
many thanks

The headers are in California and I am in Texas, but will post collector pics as soon as they arrive!

Russ

Headers shown in more correct orientation:
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I don't think it's any louder than a tubi but the sound is more baritone. The longest trip so far was about 1:30 hours, certainly not long, but I didn't find it objectionable at all. A tubi on a 308 doesn't sound too bad but on a 550, for example, a tubi system gives a positively grating, tiring, noise. That's definitely not the case with the set-up shown on my 77GTB.

The stock 308 exhaust system just sounds like s**t, in my not so humble opinion. Too much like a VW bug!

 

Upon closer inspection of the header flanges, they were a bit rough on the inside where the pipe was welded to the mounting flange. Carobu sent the headers to Burns Stainless (NASCAR header supplier), who will be re-welding on the inside of the header, then grinding the flange/port area smooth.

It was decided to ceramic coat the entire outside of the header for insulation and the inside of the header around the flange area for protection and surface characteristics.
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Without going onto a lot of detail, let's just say it turned out these Larini headers were crap - in addition to the poor welding at the port, upon closer inspection at Burns Stainless it appears that some of the tubes, owing to NOT being mandrel bent, are bent to where the inside volume would actually cause a restriction and possibly HURT the performance. They were pretty, but the devil is in the details.

Kudos To Tate Casey at Carobu Engineering (FChat sponsor) for calling me up on his own to tell me and offering a full refund. He said they would not sell those to anyone.

So now back to either fabbing up a set with mandrel bends or tweaking a stock set of European headers, which I am in the market for now if anyone has any. I had initially called Tubi and they do not sell the headers anymore.

More as our saga develops...

 

Russ,
i've been down there and have talked to Tate in person about the header issue. bottom line is that they can build you a set of mandrell bent headers however the down side is the cost $5-6k and that they are not all that interested in doing it. not sure why though, i couldn't get that info.

they had dyno tested and developed headers for the 308 but shelved it long ago due to lack of interest. it's a mystery to me and i wasn't there to create problems so i let it go.

bottom line, the stock headers are horrible. the flanges warp, the tubes are kinked and the collectors are anything but desirable for flow.

 

I've noticed that Larini exhaust components (and I think QuickSilver too) with larger diameter pipes are properly mandrel bent but small header primary pipes are usually not. They are more or less crush bent like a tail pipe from your local parts store. Making propper headers in small quantities is very time consuming and expensive.

My 77 308GTB is a Euro car and the headers are not that great either. While I've never laid US market and Euro market headers side by side, I haven't noticed much difference between them.

 

Talked to Tate again. He said that the actual collectors (there are three) are pretty good, with the flaws being the tubing bending and the flange welding. He is going to talk to Burns Stainless and see if a set of mandrel tubing can be put in, understanding it might be a bit high. We'll see - may have to tweak a pair of stock headers or something..

 

I have a pair of both a euro set as well as a stock US set off my 1977 308 cars, and would second this. The worst part I see is the stack coming out of the collector protrudes several inches inside the collector cone. What that would do for flow I cant even imagine.

 

LOL! I've had some kids say the same thing....VW Bug ........and I say..

"Not when ya' get to 8 grand, Sonny!!!!"

 

IIRC the only diff Euro vs. NA headers is the asbestos (?)/aluminum cladding of the US NON CATcars...

And with all my years I've had two header failures, with resultant engine fires......

The Header routing is the same..those "loose pieces" of that beautiful if crappy set would be built and furnished as the muffler assembly iof an ANSA #FE2020..........

As I've had failure, I vote for no cladding, but both of mine went from "fine " to "blown to eggshell bits" immediately......at the collector.