Custom Exhaust, just want to see what people have done Options

[turnaround89]

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!!

[jd74914]

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.

[Jake Raby]

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.

[rick 918-S]

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.

[turnaround89]

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?

[A&PGirl]

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.

[Krieger]

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.

[jd74914]

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? (IMG:style_emoticons/default/biggrin.gif)

[PeeGreen 914]

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.

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 (IMG:style_emoticons/default/biggrin.gif)

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.

[Hydra]

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?

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.

[spare time toys]

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.

Hi Jake, just wondering why not a Super Trap?

[Krieger]

But what kind of fun is that?

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

[Krieger]

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.

[A&PGirl]

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






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.

[CliffBraun]

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.

Hi Jake, just wondering why not a Super Trap?

Seconded, mine works fine. (IMG:style_emoticons/default/biggrin.gif)

[jd74914]

Seconded, mine works fine. (IMG:style_emoticons/default/biggrin.gif)

Fine is a relative term; it can always work better. (IMG:style_emoticons/default/smile.gif)

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) (IMG:style_emoticons/default/laugh.gif)

[CliffBraun]

Seconded, mine works fine. (IMG:style_emoticons/default/biggrin.gif)

Fine is a relative term; it can always work better. (IMG:style_emoticons/default/smile.gif)

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) (IMG:style_emoticons/default/laugh.gif)

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.

[jd74914]

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.

[PeeGreen 914]

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.

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

[ONTHEGRIND]

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