I am wondering if it would be possible to fab up my own exhaust system for my 1.8L engine. I figure i might be able to save some money this way, instead of buying a brand new one from AA or whomever and i'll learn how to make an exhaust as well. Just wanted to see what other people have done and how they went about it. Pictures would be great. I plan on getting rid of the heat exchangers if that helps out at all!

Thanks in advance everybody!!

Well, first off you will need to make some flanges to fit to the heat. The easier way to make those is by cutting the ends off of an old set of heat exchangers.

You also need to decide if you are going to run a 4-2-1 or 4-1 merge, and figure out which cylinders have opposite firing orders so you can join those cylinders for maximum scavaging.

Pipe lengths and diameters are a function of the header design you choose, your cam, the size of your engine, a power band you are looking to use most. If you are interested in any of that stuff you can look online for papers/websites on helmholtz resonance and other exhaust tuning methods. Many utilize a pressure wave which bounces back and forth, and with correctly tuned pipes can be used to suck exhaust out of the engine (aka scavaging).

The pipe diameter is a function of the velocity you want. There are also formulas to find that out. IIRC you are looking for a gas velocity of approximately 300ft/s.

After that you'll want to look around for suppliers of mandrel bent tubing (I've had good luck with Bassani exhaust).

Once you have all of the supplies and the theoretical lengths calculated the fun part starts . . . packaging it. You'll want to cut one piece at a time and tack weld them together as so you can break of pieces when they don't fit as desired. Packaging is the most challenging part, you just want to try and get the lengths as close to equal and to the calculated length as possible.

Of the non-pros I think Biggy72 (?) here probably also knows some stuff since it looks like he has done some FSAE exhaust stuff like I have.

I'm exhausted so I can write some more tomorrow, or if you want to PM me I try to help you out. The below is the start of the last set of headers I made.

This is a huge challenge. The Type 4 engine is heavily dependent upon certain exhaust characteristics. In all of my experience with the TIV engine design and tuning I have not seen ANY bolt on sub system that dictates engine efficiency more than the exhaust.

It must not be confused with ANY other engine, because thats a huge mistake that people make all the time.

Here are some down and dirty musts:

-Primary length between 30-34"
-All 4 cylinders must be "collected" ( no stupid ass dual collectors like a V8)
-Do NOT use a super trapp.

All that said, there are very good systems on the market that are proven to work, by going custom with the exhaust you assume the biggest role imaginable as what you will create has an impact on EVERY aspect of the engine from running temps to MPG, power output, RPM range and tune-ability.

Just know what you are doing isn't simple and thats why Engineered systems cost so much, some have 10 years of constant refinement in their composition.

As usual, Jake is the man. I've done some headers in the past. Here's one I did for the Shealey. The tubing size steps up larger at every junction. I'm not looking for performance beyond what the factory manifold supplied, I just had tight spaces and wanted a smoother look. I get my mandel tubes from the Chassis Shop.

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Ok, so what i have got so far it that all the cylinders need to be collected into 1, so the 4-1 is what i will go with. Already learned a lot just from the stuff you guys posted, this should be interesting and fun. What is dictated as the primary? apparently there is a start and stop point for a primary, does it start at the exhaust port on the engine and then is the hole exhaust until you hit the muffler?

When my car was running it had a custom exhaust which included (2) 21" Cherry bombs that came out in under the license plate with two tips. The donor exhaust was a old rusty monza style manta exhaust system. I'll post pictures later of it later.

I plan on making a different Cherry Bomb centered exhaust for my rebuild because the old one was uh, a little to loud.

Find yourself some used stainless heat exchangers for 300 or so and be done with it. No rust, never paint. Get a bursch muffler. This is what many people here run. PM me if interested I have a friend that has a pair of these stainless that are made for the 1.7/1.8. I don't know what he wants for them , but I bet it would be in that 300-350 range.

But what kind of fun is that?

I hate to say it (for those of you that have and like you Bursch) but Bursch exhausts sound like poop and don't help your HP any at all. Triad or Tangerine are the only ones that sound good the are not "custom".

and like jd74914 said, what fun is that

I love the Triads for a street car myself. If I was to make a track 4 I would put up the money for a Tangerine.

The primary length usually refers to the distance between the start of the exhaust tubinb and the first junction this pipe makes with another one. In this case, the exhaust port length is accounted for in the calculation as a seperate entity.
In the case of a 4 into 1 setup, primary length is that between the start of the tubing and where all tubes merge into 1. form there on, the distance between the junction and any resonance chamber (either muffler or just a big piece of pipe) is called the secondary length.
Hope this helps.

Hi Jake, just wondering why not a Super Trap?

I love it ! You could polish the heck out of your stainless and that would look bitchin!

I got a bursch at the time because it was a steal and have been satisfied, but if the thing rots out or gets wrecked I'd be open to bigger more power. I thought the tangerine is a header system-no heat. Is the triad a muffler that bolts on to the HE? Any solid data on the HP comparison bursch v triad? The sound is not as important to me.

Here are the pictures of my custom cherry bomb exhaust using a monza style manta exhaust.


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There were 2 modifications made after the exhaust had been welded up. 1 was welding a piece of metal across the two tail pipes. (Note: you might actually want to use rust proofing). The 2nd was the bracket in the picture that bolts on the back of the tranny.

Seconded, mine works fine.

Fine is a relative term; it can always work better.

IIRC Supertraps were designed for 2 strokes. The current thinking (as I have read atleast) is that 4 stroke exhaust does not need backpressure tuning like 2 strokes. You want to maximize scavaging and not play with backpressure to make torque.

That is just what I have read, I have no personal experience (except that I can't stand supertraps)

From talking to people who've played with the supertrap a lot more than I the optimal number of plates is pretty low. This leads me to believe the current thinking is wrong. I'll see if I can get more details from him.

A friend of mine with an RZ350 says he's never heard that about two strokes, FWIW.

Its very possible I'm wrong and thinking about something else. I really only have researched 4 stroke stuff and from all I have read there found that needing back pressure is a myth.

I still don't think that supertraps are good muffler solutions.

The tangerine exhaust is a complete system and yes the Triad has a header system but for the most part is a muffler that bolts up to the stock components.

I don't know where it is but yes, we did a comparison with a Stock, Triad, Monza, Bursch, and another exhaust I don't remember the name of. All of the other exhausts tested you actually lost HP over the stock. he Triad had a 4hp gain and was the only to do so out of these mufflers.

Test car was a carbed 2.0l.

I know Dave did some of his own testing as well. Maybe he has it on his site...I'll look.

Here is what I found on his site:

http://www.triadwestperformance.com/images/CRANEY_TXT.htm

We are working on a set of SS turbo manifolds actually it will be a whole hot side kit. I should have some pics avail. in a month

If you are planning on a custom exhaust system while retaining the stock HE's you need to measure the length of the HE's primaries and try to add length to the short ones and match all four before the muffler.

The Bursch muffler with its collector attempts to do just this.
Any bolt on solution that does not match the primaries does work, but not optimal.

If you look at what Foley has done, this is a tuned setup specifically designed to scavange in the best possible way with the 4-2-1 setup.

Notice the 4-2-1 setup uses opposing cylinders and scavanges based upon the timing of each combustion event. This is critical...you want to use the combustion event timing to increase scanvanging.

The HE's dont do this anywhere. They run 4 unequal pipes to the muffler...again Bursch tries to do this with the collector.
The Stock 2.0 liter muffler does this within the muffler itself, but it also not optimal.

Old school drag racers (VW motors) used just 4 pipes hanging in the wind, about 1 foot long each. That worked but many people learned about scavanging and rapidly changed to a different design.
The type one systems, and any drag racing header (4-1) is designed for WOT only..the rest of the range of operation does suffer.
the 4-2-1 system is really the best design for smooth power throughout the range of performance and driving.

Rich

The Supertrapp has never impressed me. When they quiet the engine enough to justify them they kill torque and limit RPM range.

I did a study on this in 2002 for another company and the results were as much as a 22% reduction in overall performance and as much as a 45 degree increase in CHT due to the restricted thermals.

Until you experience one of these directly compared to something more superior it seems like its not that bad... I knew they sucked since 1993 when I used one in my sandrail and could no longer climb "comp hill" in 4th gear. I removed it and went back to the previous muffler and my power came right back.

I just got a eurorace 4 into 1. What should I stick on the end of it? I was thinking a supertrap, but........

Can you post some details?

I will email the company I did the work for to see if they mind me posting it- they paid for the work to be done but that was almost 7 years ago.

Have you heard of Jay Ivey? it's odd that he puts them on his customers race engines if they're such poor performers.

I may not have posted this but i don't plan on using the heat exchangers, Ill only be driving the car in the summer on the nicest of days. too much rust work that i had to do to go and blow it by driving in snow or even rain!!

How does the exhaust system change now without the heat exchangers? All the heating stuff will be removed from the car

Well, you need a header.

4-1 is easier to build and/or easier to find used, probably the cheapest bet.

For a 4-2-1 you need to call Chris Foley and step up to that system.

If you plan to fabricate the system yourself, you should probably do some general reading on how to build a header, what primaries are, how to measure these, routing etc.

This is information that people have obtained through trial and error in what is often called R&D and its not given away freely in any business manufacturing anything that they sell.

I always chuckle when people are mad that vendors or manufacturers wont share the information on how to make a product and the key decisions behind the design of a product...that information costs money.

I suspect that no one would ever flat out ask a manufacturer of microchips or software or rocket how they are built...basically you would never expect them to share that information.

Reverse engineering has its place and if you can get your hands on a header that someone loans to you, go for it, copy that persons work.
Its not ethical, its not always legal, but its done all the time. Big firms do it all the time but they BUY the product to test it and reverse engineer it.

The key things you need to read up on.
Volumetric efficiency
Tubing size and how it affects are speed and volume.
Thermo Dynamics and the behavior of exhaust gases
Scavenge based systems
Back pressure
Muffler design and baffling.

This information is the basics and no one will step up to teach you the basics, you need to learn this stuff first.

I suspect that once you are honing in on a specific design with specific questions, Jake, Chris, and others will respond.
They just dont have the time to teach the basics that they spent years to learn themselves...

Specific questions, specific ideas that may be a tweak on an exiting design will always spur healthy debate.

So, I advise you to re-state your question and educate yourself enough to pose some questions that may be answerable.

Rich

I totally understand that a company won't release info about a product, if they did the company wouldn't exist to long. Thanks for the help. Ill do some research and start asking some questions along the way.

Perhaps he has never tested them comparatively, OR perhaps they work better than any other arrangement he has used. OR perhaps he has to use them to meet Db restrictions at some tracks and they work better at that Db level than anything else.

There are times when people make decisions based on things other than performance, even in racing.. weight and fitting challenges are just a couple. The company I did the testing for HAD to use them as they were recognized as a spark arrestor and where their engines were applied that was mandated by the USFS.

I emailed the company that I did the work for and they replied saying they don't care if we share the info. I'll do my best to capture some of the data and post it on my forums sometime in the next week.

Thanks Jake. Some real numbers will be nice. I've only compared my supertrapp to stock exhaust and it's certainly an improvement in performance there.

One thing I would keep in mind is that you can turn a supertrapp into what's effectively an open pipe with the right number of plates. I have a friend who's got around 20 on one of his bikes, still does a fair bit of noise suppression.

That doesn't take much at all... BUT it actually may be a loss of performance, its just boosting the torque at a very low RPM and it feels faster for enough of the RPM range that you may believe it's occurring all across the power band.

This happens in lots of instances, something can make more power for 500 RPM, but kill it everywhere else... A stopwatch works wonders for this. Even better than the dyno.

He primarily autocrosses his car and blasts around on the street, so torque is certainly a benefit.

One thing I love about the supertrapp system is you can prove what you're thinking pretty easily with 6 screws. More plates, less plates, no endcap, you can do any of that in 5 minutes.

Say i actually am able to make my own exhaust system, who makes a good muffler. I don't want the thing to be loud, but i do want to be able to hear the engine. Right now the sound is perfect, could i just reuse the muffler thats on the car and make my headers go into that muffler? How do i go about picking the right muffler for my exhaust setup? What brand would you guys suggest to buy from?

I like my supertrapp, they're relatively cheap and you can tune them to whatever amount of backpressure you want.

Is a super trapp the same thing found on most tuners aka the fart can? I don't want that on my car, maybe i looked at the wrong thing.

Dunno what you looked at but this is what's on my car. Doesn't sound bad (of course I can't hear anything over my intake) and allows lots of room for tuning. I don't believe it's a significantly different sound than most things you're gonna get and they're not really flashy looking.

No, not a fart can. I have seen very few hondas other than my own with supertrapp mufflers, and it is very quiet.

I had a first generation Foley type header on a race car.
Once you get the header down to a single flange, you can bolt on any muffler you want.

I had two setups and finally settled on one.
The first was a $25.00 cherry bomb from thrush, this bolted on to a three bolt flange.
the second was a hush thrush (again $25.00) muffler but it was an oval muffler similar to all the modern ones for V8 type cars running dual exhaust.

With one muffler it was perfect for the car, had a great tone, was cheap, and had very little back pressure so the car could scream at the higer rpm range.

The key was decibal levels for my choice...I need to stay under 95ish of they will pull out the sound meter.

Rich

I like the sound of the supertrapp, 1.) does the different ID for the tube affect the supertrapp at all or 2.) is that just for different exhaust setups, some with larger tubes other with smaller tubes? I figured it was the second one, but might as well ask.

I think i might buy a super trapp and work on getting the headers from the 4-1 setup.

They just offer different sizes according to what your exhaust system looks like. I think they recommend you use different size plates for different horsepower engines.

I'm using this muffler on both my honda and 914 http://store.summitracing.com/partdetail.a...mp;autoview=sku

With the honda I'm running 3 plates and it's nearly as quiet as the stock muffler the car came with. On the 914 I'm running 4 plates, and you can hardly hear the exhaust over my 40mm dellortos. I originally started with 6 plates in each car, and removing plates just kept increasing torque quite nicely.

I'm sure you'll be able to find the right combination according to what you plan to use the car for. My car has a stock cam and nicely ported heads, so it seems to like a bit of backpressure. Going from 6 plates to 4 seemed to improve the torque, but it still has pretty good top end up to the rev limiter ( 7,000 ).

I been doing some reading about designing headers and looked at a bunch of pictures to help me out, now here comes my question. Is this what a set of headers should look like for a 914, if not can anyone send me a pic of 914 headers? Sorry for taking the picture from someone classified, hope the person doesn't mind, if you do i have no problem taking it off. Thanks everybody!!

Those are the 75/76 stub pipes that attach to the HE made specifically for those years.

I will find a few pics so you can see what a Header is.

RIch

Here is Paragon products complete system.
This is a basic and well tested 4 into 1 (4-1) system.
The muffler is a simple hush thrush eight cylinder muffler with a custom tailipipe to fit through the lower rear valance.
The megaphone (cone shaped piece on the right of the muffler) would be bolted on to replace the muffler to make it really loud...

This system comes with stub pipes...the little short pipes that are in the top left of the photo.
the stub pipes bolt to the head, then the header bolts to the stub pipes.
The stub pipes make it alot easier to remove and replace the header and not disturb the head studs...which tend to come loose if you mess with them to many times.

Rich

I am not sure how well they would work on a 914 but the dyno max and flow master worked well on mustangs I have built in the past.

This is the Tangerine Racing (CFR) Chris Foley header.
The is the 4-2-1 header which scavanges better than the 4-1 header.

This systems also uses stub pipes (see a trend there)

Rich

Wow not bad and their price is pretty reasonable too at 669 bucks

Now,
The primaries are all bent all over the place to ensure they are the same length, and they fit under the car.

That is what is meant by matching primaries...notice they are different lengths in both systems and they are merging differently...

That is all the R&D these guys have done on Dynos to test their individual theories...

The 4-1 performs in one range and the 4-2-1 performs all accross the range...there are pluses and minuses to both systems and two schools that will line up on both sides of that arguement.

These are the TWO headers available for the 914. There are other 4-1 systems available by different manufacturers, but the basic design is the same and the end results are the same.

Rich

Finally,
here are the Tangerine racing (CFR) Chris Foley Stub pipes.

Rich

That tangerine system is pretty sweet. However, how many horsepower do you imagine that the extra 1700 in cost gets you? It just seems like the 1700 extra for the tangerine system could be better spent on other things... Unless you are racing competitively and in a specific class where even 2 or 3 hp can make a difference.

I could be wrong and I am sure someone will chime in but I always try to look at cost/benefit and alternatives.