Jump to content

Top End Header or stock manifold?


jbcottrell

Recommended Posts

I have a Z22 bottom end/ W53 head motor in my 510.   It had a stock cast iron manifold. 

 

I bought a Top End header and installed it today.  What I noticed is the stock manifold has larger openings than the header! 

 

Was this done for a reason or is the stocker actually better??

Link to comment
  • Replies 39
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

A lot or R&D went into the L16 'cast iron header' by Nissan. Most any exhaust manifold will flow more than well enough for stock use but the L16 manifold has 4 into 2 design with the down pipe providing an extra 6" or more of length and separation before becoming a single pipe. Long individual tubes are recognized as giving the best mid and high RPM power. This cast header was well designed and intended for factory road racing and allows you to upgrade your engine without the exhaust becoming the restrictive  weak link.

 

If you bought a header you will likely not notice anything much different unless your engine is seriously modified. You will notice that the under hood temperatures will soar, it's noisy, usually they leak but not for months and usually don't fit that great. They rust and eventually rust through.

 

Hainz is correct. Protect your investment by having it ceramic coated. This will lower the under hod temps too!

 

I had a header on my L16 back in the 70s. You know the biggest problem was choking back the disappointment with it. By then I had thrown the stock manifold away and my perfect exhaust pipe was cut up.

Link to comment

One of the reasons for the header was the fact that the stock manifold doesn't fit due to the taller z-series block. Would a stock manifold and a custom downpipe be best? Although that sounds like it might get very expensive.

 

Rubbish! the manifold fits perfectly. What doesn't fit is the down pipe that is now 3/4" higher against the floor.

Link to comment

gasket matched L16 cast header...

 

L16%20exhaust%20manifold.jpg

 

 

I have the '75-'77 L20B with the co-joined intake and exhaust. Not a fan of these as the intake does not have the coolant flow from the head through the runners to warm when it's cold and to cool when it's hot. The later '78-'80 did have this and the engines just run better with a more consistent intake runner air temperature. The co-joined manifolds use exhaust heat to warm the intake but in the summer they get baked by radiant heat. On top of this the L20B exhausts are a simple 4 into 1 pipe jamming the exhaust into a single 2"? down pipe. I like the L16/18 cast iron header which is 4 into 2, keeping adjacent cylinders separated and for almost two feet. In fact the two pipes only join on the down pipe into one and back under the vehicle to the resonator.

 

So I found a two into one down pipe at the scrap yard, no idea what it's off but the flange does not mate to the L16 manifold. It's close but larger. It isn't off a Z24 or a D21? But I held it under the car and it's sort of close.

 

So I cut the flange off and I have one of Mike Klotz's flanges from 5-6 years ago that he gave me. The new down pipe has slightly larger twin down pipes but I wrestled it on into place.

 

Need to get the head on and the L16 exhaust temp. bolted on and test fit. If all goes well I can tack the flange to the two pipes then weld permanently. This will give me the two into one down pipe and bend under the car.

 

 

 

Took my L16 exhaust out and heated and removed the very rusty eroded studs out and replaced them. Cleaned the threads with a tap.

 

L16%20exhaust%20001.jpg

 

 

Dremeled the flange to fit the larger twin pipes. Used gear clamp to pull them together for the fit. The protruding ends fit nicely up into the manifold to help the gasket seal.

 

L16%20exhaust%20002.jpg

 

 

Roughly how it will fit together. Studs are slightly long but...

 

L16%20exhaust%20003.jpg

 

 

The stock L16 twin into one down pipe joins just below the flange. This one stays separate right down to just after the bend under the car. Cylinder 1 & 4 and 2 & 3 travel 18" through the manifold and another 14" through the down pipe before joining. Sort of a long tube header. The head is another 3.5 to 4" so a total of 35.5".

 

Anyone recognize this exhaust down pipe? It visually looks like one from an S13 with KA24E even down to the flange at the back for the cat and those twin tabs in the picture below... ahhh just found out the tabs are for bolting a heat shield to them. The floor may get hot???

 

L16%20exhaust%20004.jpg

 

 

 

L16%20exhaust%20005.jpg

 

Really needs...the modified 240sx exhaust down pipe test fitted and tack welded, then final weld on the flange.

connect down pipe to the rest of the exhaust system.

 

 

Bottom row of intake/exhaust bolts were a dream to install and tighten with the L16 manifold.

 

BTW... that's a '79 L20B intake without the EGR manifold on or a block off plate. Looks almost like an L16 intake but has larger runner diameter and was port matched to the head.

 

 The head was off to repair broken studs. The exhaust welded less than a week before the Canby trip. In 3,100 miles not one problem... well the oil pressure dropped to 20 but when I got home it turned out to be the gauge.

 

Link to comment

Are those flanges still available?

I'm about to get my truck back together after looking at it dead in my driveway for two years. 

Nice little rebuild, and I'll be damned if that pencil sized rusty exhaust is going back.

Proud owner of 2 L16 ex. mani.'s...one from my beloved/lost 510, and the original from the 620.

Link to comment

Thanks Mike! So basically I need an L20 manifold with a modified (240SX?) downpipe. My manifold says A26 if that means anything.

 

Some background on the motor. The head has been ported, a .500 cam and dual sidedraft Mikunis.

 

Anyone have a suitable downpipe for sale?!

Link to comment

Are those flanges still available?

I'm about to get my truck back together after looking at it dead in my driveway for two years. 

Nice little rebuild, and I'll be damned if that pencil sized rusty exhaust is going back.

Proud owner of 2 L16 ex. mani.'s...one from my beloved/lost 510, and the original from the 620.

 

Flanges can be had from MKlotz70 at www.bluehandsinc.com

Link to comment

Negative on the L20B exhaust. Those were 4 into 1. You need any L16 even if it had the air injection tubes, which can be removed and the holes welded up. Some L18 exhausts will work but beware. The true cast header has 1 and 4 and 2 and 3 paired together. Some of the later were not so well designed and made.

 

 

Top one has the pipes just joining with no regard for separation. Bottom has 1&4 and 2&3 paired together and very separate. This is the one you want.

standardand4intotwoexhaust001.jpg

 

L20B exhausts look like this and may have round ('78 and up) or square ports ('74-'77)

s-l225.jpg

  • Like 1
Link to comment

On an unmodified engine hardly any. As I said the stock exhaust is good enough. If the engine is larger or modified the exhaust might start to become restrictive so a header may get you some gains, but it's still a small amount at an RPM you hardly ever drive at. A header is far down the list of modifications 'to do' list.

Link to comment

Well there is the cost of pipe, smaller might be cheaper, then there's what's available. Smaller, well slightly smaller, force the gasses to travel faster. Faster gas speed builds up inertia and this will drag more gasses out of the cylinder.

Link to comment

The only header to run on an L series is a long tube, Nissan Motorsports or similar header. Those short tube headers are crap. Crap hp and crap steel and crap build quality.

 

One distinction people need to make between the stock L16 manifold and a good header - 4 into 1 vs 4-2-1.

 

Nismo used to make a 4-2-1 header that was really good.

  • Like 1
Link to comment

^ this! I had shitty shorty header, loud, hot, no power. Then I worked off an exhaust manifold from the keeper, noticeably more powerful...I just went and checked, it's the 4-2-1 design mike was talking aboot.

  • Like 1
Link to comment

I know y-pipes are getting hard to find for the stock manifolds.  Mike Klotz makes a stainless 3 bolt flange. With that and a cheap collector from Columbia River http://www.mandrelbends.com/merge-collectors/parallel-2-1-merge-collectors.html, add some tubing, anyone could make their own.

Link to comment

I believe the w53 is US market smog head with smaller 35mm exhaust ports, but it's a close chamber (less apt to detonation). This head is designed for lower revving and greater torque. With your current engine configuration with a w53 on that Z22 the head is the real restriction point? As for the long header vs stock, I seriously doubt a header would give you any advantage. That being said, port that w53 and open up the valve size, and you'd see a real advantage. No instigating anything though.  :rolleyes:

 

Again, with th current configuration on your motor, I would imagine you are making in the neighborhood of 130-160hp. for that rating you want to calculate the correct diameter for proper scavenging. I use this, http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/?doing_wp_cron=1471208667.4242360591888427734375

 

I think the stock 510 exhaust was i.75", 2" is probably a bigger exhaust than you need, and I think it's the biggest ID pipe you'll get through the rear cross member without modifying it. don't quote me on that though.

Link to comment

I have a spare merge down pipe, don't know what it's off but you should see it. Looking down the main tube you can see a small hole where the second pipe bends over to and joins. The opening's nowhere near the size of the pipe welded over it. Perfect crap. It's sure to be an after market pipe. I could easily make something better but it's easy to make and cheap and why it's done this way.   

Link to comment

"I believe the w53 is US market smog head with smaller 35mm exhaust ports, but it's a close chamber (less apt to detonation). This head is designed for lower revving and greater torque. With your current engine configuration with a w53 on that Z22 the head is the real restriction point? As for the long header vs stock, I seriously doubt a header would give you any advantage. That being said, port that w53 and open up the valve size, and you'd see a real advantage. No instigating anything though. :rolleyes:"

 

The head has been ported. I can see that when I pulled the carbs and exhaust. I don't know valve sizes though.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.