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Av8ferg

Header question

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Hey, I’m on a work trip in Southern California and was searching the classifieds and stumbled on a set of headers for sale.  Guy wants $100.  He’s parting out his L28 for an engine swap.  They look stainless but might be coated, can’t really tell. 
Not sure if it’s a good deal and I really can’t tell what kind they are.  The look like either the Pacesetter or MSA 3-2.  They have two O2 sensor bungs too.  The add says N47/N42 engine setup but the pic  shows round ports to me and exhaust liners but maybe I’m not seeing it right, 
$100 seems like a decent deal since the MSA ones are $369.  BTW, was considering driving to MSA and picking up headers curbside and save on shipping if I didn’t get these used ones.   I called the store and the guy said he recommends the 3-2 headers.  His comment was 6-1 better for highway driving and 3-2 better for stop and go power?  He wasn’t helpful at all.  Also said exhaust portS were different on N47 and P79 heads (said something about diamonds shape).  I thought they were the same and he told me “No”. I think he’s wrong but I’m no expert.
Heres’s a pic of the headers for sale. 
Can anyone identify these headers and will they work on my P79 head? 
Thanks

 

AB811D51-DEAF-4779-80C1-51E7E841CB3F.jpeg

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Can’t answer question but a 100 is so cheap you should bye able to get all or most back if you decide you don’t like them.

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They don't look my msa ceramic headers. They won't turn that blue color like your pic. They look like ss to me and if the flange up top is the same thickness as msa's which matches the intake thickness just right  I think they look good for $100.

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Maybe n42 block and n47 head? They look round compared to my n42 square port header. You can see the squareness on mine. Sorry i don't have my laptop handy. Look at the pics on msa's website maybe???? Good luck with it.

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Posted (edited)

Thanks, I sent the guy a message and he said they’re round port.   Some photo investigation (shape of center flange) they appear to be pacesetter ceramic coated headers.  Pacesetter doesn’t sell SS only black or ceramic coated. 
 

you can see the flange is exactly the same. Different on the MSA, 

It comes with the Y pipe too.  For a $100 I don’t think I can beat it.  New ones are over $400.  If they suck Ill sell them.  
 

 

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Edited by Av8ferg
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Round port should work fine on a P79 head.  The P79 and the N47 both have exhaust liners that are smaller than the hole in the head casting.  It's the liner opening that needs to match and it's round.  The liners are designed to get really hot and burn off carbon and, maybe, excess fuel and oil.  Keeps the exhaust system, and the exhaust cleaner.

The first picture in this link shows the port.  You can see the liner in it.

http://xenonzcar.com/s130/Heads.html

image.png

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Thanks Cliff. I’ll order one.
 I can’t wait to see the looks I get when I drag this header and Y pipe through the company hub.  I’m also picking up some louvers too. 

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Picked up those headers today.  They were never used, so this was a good deal.   Time to finished this engine build next week.  

D58BBE6A-0B65-4E99-A065-954AEB17E7BC.jpeg

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Can't beat that deal!   If they work out, I can loan you a PLX wideband o2 kit with gauge to see what your afr is when you get the motor in.

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3 hours ago, S30Driver said:

Can't beat that deal!   If they work out, I can loan you a PLX wideband o2 kit with gauge to see what your afr is when you get the motor in.

Cool, not sure what that is but happy to learn.   I noticed one of the O2 nuts is missing,  Maybe it comes that way.  Wasn’t sure if I needed to install an O2 sensor, not even sure if my 77 had one.  

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Posted (edited)

Nope, no O2 sensor on the 77, not until the ZX.   You need a second nut if its missing to seal the exhaust or screw in a sensor.   With a wideband O2 sensor installed, you can monitor the air / fuel ratio of the running motor throughout the rpm range.   Nice to know if running too lean,  14.7 is considered ideal.

Here is the gauge without the O2 plugged in.

Plx.jpg

Edited by S30Driver
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I have a very unhealthy AFR fetish! I put this together based on quite a lot of hours of reading / internetting / speaking with engine builders / tuners and trackside mechanics at classic races.

 

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Heads up: 14.7 as correctly stated above is the ideal mix to get a full burn and is good as your idle baseline afr. There are of course many situations that you want to be either side of it.

 

With modern fuels, the consensus in research papers / controlled experiments is that optimum power is produced between 12.5 - 12.8. Aim for this across the range at WOT. On a side note, some modern engines prefer just north of 13 due to head designs etc.

 

If you are planning on hooning it at max revs in 4th on the long straight of a race track, racers typically aim for closer to 11.5 as the richer mix has a cooling effect on the engine (but without going into details, it does put a stress on it too). My L28 AFR sits doggedly between 12.2-12.9 from 3.6K to the 6.5K rpm limit and pulls like a train. I have ran it at 11.5-12 and the engine is marginally but noticeably keener on the transition from part throttle to WOT; however the power difference is difficult to discern without a rolling road.

 

I find anything 11 or below loses power / makes the engine bog down.

 

On the cruise you ideally want to be north of 14.7 if you have a working vacuum advance. Ideally 15.5-16ish. This makes for a slightly hotter cruise but will give you way better fuel economy. Modern cars can tolerate HUGE timing (c. 60 degrees) and with super high pressure common rail injection

/ better atomisation run even leaner.

 

Anything north of 17 on the overrun will give you fun pops and crackles on the tail pipe at around 3k-4K rpm. My L26 running a little lean once shot out a 2 foot flame out the back when coming off the power at 6k rpm. Scared the b’jeesus out of me but my friend following thought it was mighty impressive! ;)

 

The other thing you will be surprised by is just how much a mere 0.5 difference on the AFR can affect your fuel economy and richness of the sweet aroma of your exhaust.

 

Whatever you do, don’t run your engine lean on WOT as it does horrible things to your exhaust valves and piston crowns.

 

Welcome to the rabbit hole of the AFR gauge - you just took the red pill ;)

 

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