The 230 Headerfold project

[monkeymissile]

exhaust down under

Cyl #1 or 6 would be the candidates for a thermocouple- you want to get into the gas stream, not surface temp. Here's an Austrailian Jeep site that is going our way http://go.jeep-xj.info/HowtoExhuast.htm .

glad to see that other people are paying attention to the details too. To be honest, I never realized how complex an exhasut system actually is. I have found all of this new knowledge fascinating and it's definitely helped me guide my design. I hope to have some computer images of the latest design by the end of this weekend.

[maineSS]

Cyl #1 or 6 would be the candidates for a thermocouple- you want to get into the gas stream, not surface temp. Here's an Austrailian Jeep site that is going our way http://go.jeep-xj.info/HowtoExhuast.htm .

[monkeymissile]

temps

Any idea how hot those pipes can get under normal to moderate use? Seems like 1200 is a bit on the high end.
It would be cool to develop a water jacket for the header to keep it cooler. I've seen them for antique motorboat headers, very cool (har har).
I assume my leanest cylinder would be the one(s) farthest from the carb? I might have access to a decent thermocouple

[maineSS]

You've accumulated a lot of info, the key is finding which is usable. Looks like one of the more important questions is "How hot will it get?" I originally mentioned coatings as a guard against fire hazards, but the Jet-Hot oxidation tests show why cheap headers never last very long. If temps consistently run over 1200 deg, Stainless isn't really cost-effective either. It looks like header surface temps are within 100 deg of the exhaust gas, so fitting an exhaust manifold thermocouple to your leanest-running cylinder may show whether coated steel or Stainless is the best material. I ran a 70% VE airflow number for the 230 through one of Vizard's header formulas, and came up with a figure very close to your 1.375" primary dia, so it looks like you're pretty close there.

[monkeymissile]

You are quickly becoming the expert on this project, and rightly so as it is your project. I certainly agree that maximizing the 230's performance is a strongly desired goal. However, the words "robust and worry free" describes the basic character of these trucks. They are qualities I would not want to lose in an upgrade.
Press on, Justin, you're doing good.

John,
thank you for the kind words and encouragement. They'll come in handy later when I go through my "do you really need to be doing this?" stage.....

[John Waak]

You are quickly becoming the expert on this project, and rightly so as it is your project. I certainly agree that maximizing the 230's performance is a strongly desired goal. However, the words "robust and worry free" describes the basic character of these trucks. They are qualities I would not want to lose in an upgrade.
Press on, Justin, you're doing good.

[monkeymissile]

good links

http://www.carcraft.com/techarticles...ics/index.html

- has easy to understand equations. According to them I want 1.375" primaries for a peak RPM of 3000. Ha, that's what I initially guessed!

http://www.superchevy.com/technical/...der/index.html

[monkeymissile]

fascinating stuff, that guy really knows what he's talking about. I guess I keep thinking that the 230 is just too small and an M-Series RPM range so low that a lot of this info doesn't necessarily apply in the same way. I think the trick is to extrapolate the most critical principles and make it work for this application.
For instance, does anyone specialize in low RPM headers? Off to Google!

[maineSS]

There's some interesting data on header coatings at this site- http://www.centuryperformance.com/heatwraps.asp . It has some Jet-Hot test results on header oxidation at 1200 deg (dark red in daylight) temps. A set of 1010 steel headers lost 25% of its weight in 10 hrs, 410 Stainless lost 8% in the same time. Coated 1010 lost no weight. Another test involved running a car with identical headers, one coated, the other not, for 10 laps at 6900- 7500 RPM. The uncoated header was 750 deg 1" from the engine port (red visible in dark), the coated header was 300 deg 1" from the port. This site has a comparison between three different coating types using thermocouples and IR photography- http://www.flirthermography.com/medi...onte-FINAL.pdf .The orange-red to orange white colors seen in some header photos would be 2010- 2190 deg, unprotected steel would oxidize even faster at these temps. It would be interesting to see how hot headers get on a flathead under load- if there's a lot of fuel burning on it's way out the exhaust due to an inefficient combustion chamber, header temps could soar. Perhaps SickCall could get some measurements with an IR gun on his header after a long hillclimb? I know the muffler on my truck gets hot enough to warm the floorboard! One other thing about coatings is that they fuse with the metal, making any subsequent welding just about impossible, so it should be the last thing you do before installing them on the vehicle.

[MoparNorm]

You might consider doing the inside of the header with a thermal insulating coating- that would give most protection for the buck. Exhaust gases can be quite corrosive, and corrosion activity doubles with each 10 deg rise in temperature (your car rusts faster during the summer than winter, and pulling a snow covered vehicle into a heated garage helps the process along nicely). Another thing to keep in mind during the design process is access to other engine components- we've all wondered why the OEM's bury things that require periodic maintenance. The oil pump is probably one of the things you'll want to keep in mind- wouldn't be much fun having to dismantle half the exhaust to get it out. I've also looked for Tri-Y systems designed with wave tuning in mind, but so far no one seems concerned with it- it looks like it's considered to be a step between factory exhaust and regular headers.

As noted in my post, the coating is applied BOTH inside and out.
Tri-Y headers provide about 20% more performance than traditional headers, by dyno testing.

As for making a modified header, you're going to discover that, with a limited production run, your costs are going to be about the same, no matter what you build, so my advice is to make it the best you can make it. I'd pay $600 for an excellent set of headers, I won't pay $550 for a marginal set.

[monkeymissile]

your preferences....

One of the voices in my head is getting louder everytime I sit down to work on this headerfold design....."keep it simple stupid!" it says.
So I have been thinking that I could design something much simpler, along the lines of the stock manifold, and easily use stainless. I'd probably end up with something that performed marginally better than stock, but was robust, worry-free and easy to install.
Or I could try to get more performance by applying more principles of header design, but would likely have to use steel tubing and get it coated for longevity. Also it would be much harder to build, probably trickier to install and likely to make getting at the oil/fuel pumps difficult.
What would you all prefer if you had a choice? I am leaning more towards the first option using stainless.
Appreciate your input, thanks

[monkeymissile]

You might consider doing the inside of the header with a thermal insulating coating- that would give most protection for the buck. Exhaust gases can be quite corrosive, and corrosion activity doubles with each 10 deg rise in temperature (your car rusts faster during the summer than winter, and pulling a snow covered vehicle into a heated garage helps the process along nicely). Another thing to keep in mind during the design process is access to other engine components- we've all wondered why the OEM's bury things that require periodic maintainence. The oil pump is probably one of the things you'll want to keep in mind- wouldn't be much fun having to dismantle half the exhaust to get it out. I've also looked for Tri-Y systems designed with wave tuning in mind, but so far no one seems concerned with it- it looks like it's considered to be a step between factory exhaust and regular headers.

mSS,
I've considered a design that has weld-on retainers in key locations so that sections of pipe could be easily removed to gain access to oil pump/fuel pump without full removal, something like these...
http://www.spdexhaust.com/AccessoriesB.html

[maineSS]

You might consider doing the inside of the header with a thermal insulating coating- that would give most protection for the buck. Exhaust gases can be quite corrosive, and corrosion activity doubles with each 10 deg rise in temperature (your car rusts faster during the summer than winter, and pulling a snow covered vehicle into a heated garage helps the process along nicely). Another thing to keep in mind during the design process is access to other engine components- we've all wondered why the OEM's bury things that require periodic maintainence. The oil pump is probably one of the things you'll want to keep in mind- wouldn't be much fun having to dismantle half the exhaust to get it out. I've also looked for Tri-Y systems designed with wave tuning in mind, but so far no one seems concerned with it- it looks like it's considered to be a step between factory exhaust and regular headers.

[monkeymissile]

convenient

The shop is in Auburn WA. right next door to the header fabricator. It's about $255 and the chrome is $50.
We could get a better coating price if we had more volume.

http://www.performancecoatings.com/

that's about the range I've been seeing too from other vendors, thanks

[MoparNorm]

The shop is in Auburn WA. right next door to the header fabricator. It's about $255 and the chrome is $50.
We could get a better coating price if we had more volume.

http://www.performancecoatings.com/