More power switching to 4-2-1 headers?

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More power switching to 4-2-1 headers?

Post by andyf » Sun Aug 04, 2013 2:38 pm

I have been flogging this 514 inch Mopar engine for a few years now and we have continued to gain power over time. I've been using the same dyno headers for several years now but I'm starting to wonder if maybe that is the next opportunity. These are 4 into 1 Stahl headers. They fit nice and seem to make really good power but I'm wondering if a set of 4-2-1 headers would wake things up a bit. Engine is making 895hp uncorrected at 7000 rpm, torque is 710 uncorrected at 5500 rpm. When I had these headers built the engine was making about 700 hp so things have changed a bit.
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Re: More power switching to 4-2-1 headers?

Post by Alan Roehrich » Sun Aug 04, 2013 2:51 pm

Possibly. But odds are you'll need to change the camshaft, and probably the firing order. You'll spend a ton of money, most good 4-2-1 headers are 3 times the price of a set of Stahl headers, and you'll probably buy 2 cams to get there.

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Re: More power switching to 4-2-1 headers?

Post by RAS » Sun Aug 04, 2013 3:05 pm

Alan is right. Your deal looks tough to improve on. 895 HP! Back in the 60s Mickey Thompson had a super scavenger header I though in theory anyway, looked really promising and sounded excellent. No one ever copied it so I guess it was just a sensational promotion that had limited sales success. Mickey usually killed it so this may have been one of his few stumbles. I think the NSACAR guys have headers pretty much figured out. After all who has spent more on it than them? Good luck.

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Re: More power switching to 4-2-1 headers?

Post by bigjoe1 » Sun Aug 04, 2013 4:20 pm

DO NOT WASTE your money.. Very little improvement to be had.


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Re: More power switching to 4-2-1 headers?

Post by MadBill » Sun Aug 04, 2013 4:25 pm

Many here (including me) have been pleased with the results of Speedtalker Larry Meau's inexpensive PipeMax program for speccing exhaust systems. If you feel the itch to tweak it, comparing your current specs to PM's recommendations would show you how close to optimum it is.
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Re: More power switching to 4-2-1 headers?

Post by PackardV8 » Sun Aug 04, 2013 4:34 pm

Back in the 60s Mickey Thompson had a super scavenger header I though in theory anyway, looked really promising and sounded excellent. No one ever copied it so I guess it was just a sensational promotion that had limited sales success. Mickey usually killed it so this may have been one of his few stumbles.
IIRC, that M/T header design was the result of trying to replicate dyno header performance with street headers which would actually fit into a Buick chassis. The resulting staggered pipes exhausting into a square collector had a really nasty metallic ping or clang. That may be one reason they're not made today. More than one set of M/T was pulled off after a short period of street/highway use.

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Re: More power switching to 4-2-1 headers?

Post by lorax » Sun Aug 04, 2013 4:41 pm

RAS wrote:Alan is right. Your deal looks tough to improve on. 895 HP! Back in the 60s Mickey Thompson had a super scavenger header I though in theory anyway, looked really promising and sounded excellent. No one ever copied it so I guess it was just a sensational promotion that had limited sales success. Mickey usually killed it so this may have been one of his few stumbles. I think the NSACAR guys have headers pretty much figured out. After all who has spent more on it than them? Good luck.
The M/T header wasn't so much a tri Y as it had a looooong collector and the pipes were staggered inside in a effort to make the pipes the same length without all the twisting normally associated with equal length headers, It didn't work. :D
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Re: More power switching to 4-2-1 headers?

Post by Alan Roehrich » Sun Aug 04, 2013 5:07 pm

No doubt PipeMax will get you close to optimum on the headers. And talking to the right cam guy will get you close on the cam. The question is, will you gain enough to justify the expense and effort? If you spent $3K+ on the headers, and $800 for two cams, , plus $1K for dyno time, to gain maybe 20HP and 20ft/lb, is it worth it? It might be for a class car. You may also make some gains in average torque/HP.

The normal approach is to go to either a "B" firing order, or if possible, a "C" firing order, take 4-6 degrees off of the previously optimum exhaust duration @ 0.050", and add some to the intake 2-4 degrees @ 0.050" usually, it usually takes some fooling with both the LSA and the ICL as well. What you're trying to do is take advantage of the improved scavenging by "shortening" the exhaust lobe and using the "room" you gain to give it a little more intake lobe. It fills the cylinder a little better, and allows you to blow the cylinder down better with less duration, so that you don't lose cylinder pressure that might be used to make torque, and you don't lose some intake charge out the exhaust trying to make sure you blow the cylinder down completely.

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Re: More power switching to 4-2-1 headers?

Post by andyf » Sun Aug 04, 2013 5:40 pm

I used PipeMax to design the existing headers. I sent the specs to Stahl and he built the headers from the PipeMax numbers. PipeMax tends to want a ton of valve lift which is actually hard to come by with these cylinder heads. I ended up with a 1.85 rocker arm ratio and was able to get a little over 0.800 lift but it still isn't what PipeMax recommends.

Changing the firing order is an option of course, but I'm not sure there is a lot to gain by doing down that road. Maybe the firing order needs to be changed to work with a specific header design? As far as I can tell, the firing order doesn't matter much when using a 4 into 1 type of header but maybe someone has found something that I don't know about.
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Re: More power switching to 4-2-1 headers?

Post by wyrmrider » Sun Aug 04, 2013 6:01 pm

What heads?
whose rockers
compression bore and stroke and rod?
BTW MT headers worked just fine in a cramped chassis
We need more like MT thinking outside the box.

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Re: More power switching to 4-2-1 headers?

Post by andyf » Sun Aug 04, 2013 9:12 pm

I re-ran PipeMax with my current engine config and it recommends a slightly larger primary diameter and a slightly shorter length over what my current headers are. Evidently the changes I've made over the last several years have moved the power peak up enough that PM is now recommending a little bigger header. Looks like a fairly easy header to build although it isn't going to be an off the shelf deal.

I also did the calculations for the 4-2-1 header in PM and it looks like a weird header. 15 inch primary tubes then the 2-1 Y and then another 15 inches to the second 2-1. So the primary pipes would basically just come out of the head and curve down then go into the first pair of Y's. I suppose they could be built that way for the dyno but it would look odd. I suppose if I had the skills I'd fab up a set myself just to see if it worked. Not so sure I want to pay a pro to build them since they would probably cost more than my budget can handle.
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Re: More power switching to 4-2-1 headers?

Post by Walter R. Malik » Sun Aug 04, 2013 11:21 pm

Are you talking about a 4-2-1 "collector" or a true tri-y 4-2-1 ...?
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Re: More power switching to 4-2-1 headers?

Post by andyf » Mon Aug 05, 2013 6:33 pm

Walter R. Malik wrote:Are you talking about a 4-2-1 "collector" or a true tri-y 4-2-1 ...?
I don't care, I'll try most anything that seems like it might work. I have a fairly impressive pile of stuff that didn't work so it certainly isn't a perfect process.

At the moment I'm leaning towards just having a new set of 4 into 1 headers built using the updated information from PipeMax. If someone has some data that says a different approach would be better then I'm all ears. I have the input form filled out to send into Burns. Maybe they'll give me something new to chew on.
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Re: More power switching to 4-2-1 headers?

Post by Barry Burch » Mon Aug 05, 2013 6:43 pm

Changing firing order has more to do with engine cooling
than any thing else. When the ajacint cylinders fire next to each
other it best to have them firing close to the front of the engine.
Because the water pump pumps from front to rear.

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Re: More power switching to 4-2-1 headers?

Post by Walter R. Malik » Mon Aug 05, 2013 11:03 pm

Barry Burch wrote:Changing firing order has more to do with engine cooling
than any thing else. When the ajacint cylinders fire next to each
other it best to have them firing close to the front of the engine.
Because the water pump pumps from front to rear.
With a true Tri-Y ... different firing orders WILL change the location of the cylinders which fire next to one another side for side so, with a Tri-Y it changes a lot more than simply cooling.
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