US Headers & Exhausts NA

plohl · Postby **plohl** » Mon Aug 18, 2014 4:29 pm

project.r beat me....

Dupain wrote:Give me some data. Give me a reccomendation on a 4-1 to buy.

Racing beat....

Dupain wrote:How many here have 4-1 headers on their 5? ZERO.

There are a number of cars that run 4-1 exhausts, mostly I know of a number of people running Racing Beat exhaust manifolds which are quite a popular choice in the US, and are easily to get in Aus now as there are 2 sponsors on this forum selling them, AutomotivePlus (mx5Plus) and Deckspeed racing. Racing beat also have quite a bit of information about the development of the exhaust. If you were to say, search buy miata 4-1 exhaust manifold http://bit.ly/1n035co, you would find said information. I also know of cars running 4-1 exhaust manifold in the prod sports series in QLD, some of these have been developed by GLS Engineering... on an engine dyno.

Dupain wrote:I'm giving it a go - evidence based analysis, not some hearsay. Baseline dynos are available. We'll see how it goes on the dyno.

Well done. I look forward to seeing the results. Regardless of your findings, the manifold still is not equal length, which the company claims.

Dupain wrote:The bullies on this thread, do you actually drive/ mod your cars? Or just park it and talk shiit all day on the forum?

Most of the people that have commented here opposing the argument you have so, eloquently put forth, have quite a lot of mechanical, motorsport, manufacturing and engineering experience (just to name a few).

Here are some good references:
Bell, A. G. (1998). Four-Stroke Performance Tuning. Somerset, UK: Haynes Publishing.
Blair, G. P. (1999). Design and Simulation of Four-Stroke Engines. Warrendale, PA, USA: Society of Automotive Engineers, Inc.
Smith, P. H., & Morrison, J. C. (1971). The Scientific Design of Exhaust and Intake Systems, 3rd edn. USA: Bentley Publishers

Bell is pretty easy to digest, the other two... not so much.

gslender · Postby **gslender** » Mon Aug 18, 2014 5:00 pm

Dupain wrote:Give me a reccomendation on a 4-1 to buy.

I'm not sure how hard you looked, but OBX (another low cost brand) also sell a 4-1 header for what looks like ~ $200 USD
http://www.obxracingsports.com/products.php?pk=1763#
...at least this product, actually looks like a 4-1 equal length/tuned header.

What you've bought looks like an expensive unequal length header !?

One thing that has me puzzled, is why would they go to the extra effort of that cyl 1 extra long primary if they didn't think it was needed. I mean it looks stupid and certainly against any common approach to header design, but you'd have to ask - why? The additional time/effort and extra steel, but what for?? What were they thinking and why not just build it like any other header. Was the goal to attract people who don't know any better and/or think... oooh, big curly pipes... must go faster with big curly race pipe... yeah, me must have them!

G

hks_kansei · Postby **hks_kansei** » Mon Aug 18, 2014 5:36 pm

I almost wonder if the header they designed was for another car with the exhaust ports on the opposite side of the head (so super long #1 would actually be #4), if that was the case it may have been as simple as they just mirrored the collector position without also mirroring the primaries?

sailaholic · Postby **sailaholic** » Mon Aug 18, 2014 5:52 pm

I had a tuned Apexi 4-1 with a super spiral collector as did Plohl.

We both sold them for 4-2-1 designs as they are better suited to cars that see the street.

Your looking at this from a straight chemical engineering / fluids procession point of view and not considering the effect on the mechanical system of an internal combustion engine.

Not sure where you were going with multinational / vs backyard comment.

tbro · Postby **tbro** » Mon Aug 18, 2014 7:49 pm

Dupain wrote:
ManiacLachy wrote:Yeah, Danny has no experience and doesn't know what he's taking about at all. Certainly isn't an expert. /sarcasm.[/quote

The bullies on this thread, do you actually drive/ mod your cars? Or just park it and talk shiit all day on the forum?

Oh!!! look at that, the way they should be

Masta been there for the BBQ I suppose, My car, I built it

You would want to hope I know something about MX5s

And BTW, the only 1.6 in the field, 3rd in 2f at that meeting, the rest of the field, Prodsport 1 hour 2010

Yes we were lucky, but hey smartarse, at least I do it.

Have a nice day

Jeo · Postby **Jeo** » Mon Aug 18, 2014 8:19 pm

(unrealted, but holy crap I'd almost forgotten about Boxxy)

sailaholic · Postby **sailaholic** » Mon Aug 18, 2014 8:30 pm

Dupain wrote:Looks ordinary.

Lol. I hope for your sake this is all just a big troll.

Otherwise your just rude and pig headed.

Pamex · Postby **Pamex** » Mon Aug 18, 2014 8:36 pm

Dupain wrote:How many here have 4-1 headers on their 5? ZERO.

The bullies on this thread, do you actually drive/ mod your cars? Or just park it and talk shiit all day on the forum?

I'm bored, so why not.

In response to your first line here... so what if any of us have 4-1 extractors on our cars? Does that mean we don't understand the theory behind them? I'm paid to specialise in certain gearboxes. Does it mean I have one on my car? No. Does it mean I know nothing? No.

On the second comment, you're arguing with some very knowledgeable people here, and some are paid to specialise in this area. Park it and talk sh*t? Mine has 450,000km on it, and I'm currently doing a ground up resto. Every. Single. Component and nut and bolt refreshed. I'm not alone, most people in this thread have done a lot of work with MX5s.

That said though, you're adorable. Keep fighting the good fight.