amso3

I've tried searching and can't seem to find the best tube size and length for a 2005 S2000 engine. The engine is in a Morris Minor and I'm about ready to fab the headers. The stock or aftermarket headers will not fit in the space so I 'll create something that does. I've built headers for Porsches and work with tube dia and optimum length (looking for more torque not high end HP). Any solid info would be appreciated


2005 S2000 engine, trans and full S2000 suspension with Ride Tech coil overs

Manga_Spawn

Man that looks amazing. Not sure as to your question I was trying to look at some of the headers with more documentation around their development like the Urge Unicorn header but not really seeing details like lengths and diameter for the piping.

Chibo

I think it'll be hard to find what you want since very few of the off the shelf headers for our motor had the development time put into them. Have you looked at PipeMax? I believe Vibrant Burns also has a service for determining optimum piping diameter / length.

Mnstr2000

FWIW a turbo manifold conservative turbo and downipe might fit your project very nicely, as far as header length note HKS twisted tube either did that to increase length or make a marketing ploy, they seem to feel longer is better.

flanders

The stock header is very good and most aftermarket ones gives very minor gains, sometimes they are even worse.
So I would use the stock one as a starting point for lengths and diameters and maybe compare to some of the aftermarket ones for guidance.
Toda provides some measurements on theirs for example https://www.toda-racing.co.jp/en/pro...c-torquie.html

amso3

Thanks I will measure the stock ones. When I built headers for my Porsche Burns stainless designed them. I didn't think I could accurately complete the S2000 engine spec form but I guess I'll give that a try next

clio

When the S2000 was released Mugen issued an article for their product development. Here is an extract. Perhaps it might be of some use. I copied from pdf, the formatting isn't so great!

During the development, the performance test on the exhaust manifold by so many different specification had been conducted and as a result, we were able to obtain many data. Some of them are as follows:

A. 45mm diameter of the primary manifold is better than that of 48mm.
B. When compared between 4-1 and 4-2-1, 4-2-1 is better in overall. General notion that 4-1 is for the high speed and 4-2-1 is good for the middle speed range is not necessary applicable to F2OC.
C. Exhaust manifold of standard specification was an ideal specification as expected. It is also a collector configuration aimed at the peak power output.
D. Regrettably, however, since the emphasis is placed on the mass production, the standard parts have the different primary manifold lengths for each cylinder and therefore, the engine performance between 6000 and 9000rpm is not necessary the best.

Actual running test has confirmed the following.
A. Since there is a brake master cylinder placed near the exhaust manifold, it is indispensable to place a heat insulation material such as heat insulation plate between the cylinder and the manifold. We have actually confirmed that there was overheating phenomenon when the test was run without such a heat insulation.

From the result of the test conducted, we decided the specification for Mugen's exhaust manifold as follows:
A. For the primary manifold pipes, a diameter of 45mm has been adopted.
B. The length from the exhaust port to the collector has been optimized and now have completely equal lengths.
C. 4-2-1 layout has been adopted.
D. A collector s configuration which emphasizes the torque performance from 6000 to 8000rpm has been adopted.
E. For eliminating the overheating problem, an exclusive metal molding has been installed to make new heat insulation plates.

Objectives for the development of Mugen sports exhaust system.
1. Lighter weight.
2. Use of titanium material: Use stainless alloy for the high heat area and titanium material for the lower heat area in order to achieve a balance between the durability and lighter weight.
3. Optimizing the pipe s diameter: If the pipe s diameter is increased excessively, that will result in power decrease. It also produces banging exhaust noises which in turn will require larger silencer as well as inner silencer which can significantly resists the exhaust pressure. The exhaust pipe diameter appropriate for F2OC engine is about between 60mm and 70mm and there is no noticeable change in the maximum power output in this range.(At below 6000rpm, there is no torque change seen even when the diameter of the exhaust pipe was changed, due to the effectiveness of the valve timing control on the V-Tecs low speed range). As a result of our repeated test on the dynamometer, we selected the pipe s diameter of 60, 5mm which is the minimum size requirement, and 45mm for the extension of pipe after the junction manifold. (More than 1/2 of the cross section area of the main pipe after the junction section is not necessary and if the diameter is smaller, the silencer

amso3

Thanks Clio, good information