All the design was done by 1920. We've just been applying materials tech development since then. Computer tech has been just more of that in a way.
Ever check out a Miller race car from the 1920s? Twin over-head cam, I think it had four valves per cylinder, supercharger, intercooler, front wheel drive, inboard front brakes.... The last 2 features have fallen out of favor for most high performance applications but it does show those guys were thinking more than 80 years ago.
Gothspeed on fchat is an engineer and did exhaust system design and is doing some now for 348's. He is our 348 madscientist. maybe a consultation with him may be beneficial. My understanding is that theory will get you there most of the way and the rest is black art. Maybe he could give you good ideas.
Well get him over here You're right that at the end of the day you have to put it on a dyno to know what works. Generally the engine is more sensitive to the intake track length/tuning then the exhaust so as long as the exhaust is close the end result will be pretty good. The real trick is going to be finding mufflers that flow enough air without making way too much noise. Im thinking 2 ½ OD pipe from the 4 collectors out should do it. I should think about some way to easily remove the mufflers so I can dyno with and without to know for sure what impact they are having on hp.
Oh absolutely! We ALL need to have mufflers that are easily removed.............for testing of course.
Okay I'm getting upset with lack of stimulating pictures ... all this talk about graphs and computer packages, enough to drive a man to drink! Pete
>> I'm starting to see the headers are going to be pricey to build. Nice collectors are $200-$300 each it looks like and need 4...I'm going to end up with a couple thousand dollars into the exhaust system. As for the muffler part, I think that this concept is the best one I have seen anywhere, plus it uses magnaflow components, (except for the Ansa tips), that are very cost effective if you buy them from Performance Peddler. http://www.ferrarichat.com/forum/showthread.php?t=221119
I know, I know but I'm still EFI installing on the 2Vi 308 for someone else. 2-3 more weeks, I keep running into delays. While it can be a bit boring this part of the project with the graphs is probably the most important to the outcome of the project. The decisions I make here will pretty much completely determine the character and performance of the engine when its done. This part of the project applies to just about anyone whos thinking about hopping up their engine, the first set is to make a plan and select parts that complement and work with each other. Change based on Hope or simply for the sake of change is not a plan or a reasonable strategy (a little political humor for the US readers ), solid planning and engineering need to drive the change.
I'm planning to steal Russ's design almost exactly....no need to re-invent this part. It's still expensive though. 4 SS mufflers at $100+ each, tips, pipe, clamps to make it removable and I'm looking at probably around $800 from the headers out.
Why four mufflers? Can't you merge the output of each side's two three-way collectors into a 3 inch tube and then run the set up like Russ has it, only with larger cores?
I found these resonated tips that are probably a lot more reasonable than the Ansa ones and come in a bunch of sizes: http://www.jegs.com/p/Hedman/969187/10002/-1 The Hookers are even cheaper but they don't have the 9" long model I'm going to need. If you could take it down to two 3" outlets, these Hookers are really cost effective and resonated just like the Ansas. http://www.jegs.com/p/Hooker/744873/10002/-1 Kind of "ricey" though...
Russ used 2 mufflers in series and was happy with the sound and performance. I'm looking for about double the flow, so 2 systems like his would probably work well so I though it would be a good place to start as it's been tested. I very honesty don't know what would make the best system. By the time you get to 4 cylinders you are very near to steady state flow and adding cylinders means you need to go bigger to handle the additional flow. Going from a 2.5" to 3" is nearly a 50% increase in flow area and about exactly what would be required to go from up to 4 cylinder to 6, so it's a possibility. The next variable is system volume. Normally the larger the better for sound reduction without adding restriction which is part of the reason the stock mufflers are so big. It's also commonly accepted that 2 mufflers in series of X volume muffle better than 1 of 2X volume, but I can't see how they would flow as well. 2 larger mufflers would be cheaper, lighter and would probably flow better. Then that could be either a 2in/2out common inside, 2in/2out separate inside to 1 in 2 out I guess. All would be louder than the 4 muffler system and all would sound and perform differently. Maybe I should build what I think would be the lightest and most free flowing and see if I can live with the sound. There should be enough low end that normal driving can be done at low rpm which is fairly quiet .I'm just not sure I really want the whole valley to know when I'm not driving normally.
What ever you design, you should only consider using 304 (or better) stainless steel. I've built too many systems out of carbon steel and then been disappointed by rust damage in short order. Stainless holds the heat in better too. I built the system on my 308 using 2 Magnaflow single pass stainless mufflers and terminated it with stainless outlets from Magnaflow also. I don't think it's too loud under normal conditions. On the dyno, when I was standing next to the car, it really howled though - sounded great! I always behave myself in my own neighborhood. It's better not to sh*t where you eat. I don't even want locals SEEING me going fast, let alone hear it.
I'm planning 304 for everything up to the tips for sure. For the tip though chrome sure does look nice as well as original. I did put polished 304 tips on my stock muffler when the original chrome tips needed replacement and they looked good, but they just didn't seem to look as good as chrome.
I'm still busy with the side efi project but I have to walk right past the TR head sitting on the flow bench every time I go into the shop which turns out is probably a bad thing. My thought for some time now has been that I should cut out the top of the port and weld a new piece to get the flow area I want. My new thought is the old though was just stupid. What I really should do is just put the head in the mill and punch a new port hole at an angle/position that blends to the current port about 1/2" inside the seat then heads out so the top just leaves enough room to put the cam cover on. I think I could raise the port about 15 degrees .just enough the give me room to keep the 2 banks from hitting in the middle with the tuned length I'm looking at....hmmmmm
Here's the basic idea. I'd have to check the valve spring pocket, it looks like I lose a lot of room there. blue line are the current port, balck the proposed Image Unavailable, Please Login
Does anybody reading this has a testarossa service manual with a section view of the head and ports or a like to one? It would make planning the port move a lot easier.
I'm here -- I had to scan them Mark -- send me a PM with your email address, and I'll email the full page WSM scans in a better quality: Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
I'd be amazed if you could lift the port up that much. Surely a reasonably modern Ferrari head would have fairly steep-ish ports anyway? Usually you would have to make the valve longer to move the return springs higher, which ofcourse means the camshaft has to move, etc. Also wouldn't you be able to make the trumpets simply cross in the middle of the engines V ... thus why the need for steeper? Pete
Pete, My thought exactly. There appears to be very little material to play with, taking into account that the ports in the new situation are already not the same as the ports in the standard head. Not only do you run into trouble with the recess of the spring/spring-seat, but you also run into trouble on the outside of the head, the latter can of course be built up to suit. Crossing them over appears to be the easiest solution, but with writing that, I realise that the word easy doesn't apply here other than being a red flag.
I thought the same thing but it looks like they pulled the port down as much as they dared to keep the manifolds to a reasonable width with the flat engine. The valve angles are much bigger (ok a couple degrees, but it looks like a lot) than the QV/328/348 head. What I'm looking at is I won't hit the 800 number if I can't cat 160+ cfm (at 10"h2o). The outlet of the port is smaller than it needs to be to work properly but I've already hit the oil galley leaving to only option a new roof in the port. A new roof in the port is quite a bit of welding to tie it in on the sides. Slipping a tube in makes the port even better and is a lot less welding. In my twisted little world this is the most reasonable way to go. See how that works and how I got into the mess Im in?
