The Aftermarket Cylinder Head Thread!!

[jon93PGT]

Ok, so I'm currently getting a set of ZE heads built up for my boost project. Well, I have been searching and reading every post I can find that discusses the valvetrain for the KL03 and the KLZE.. As well, I've been researching the aftermarket companies and what they have to offer in terms of parts. Well, I thought it would be good if there was 1 comprehensive thread that sort of listed all pertinent info pertaining to heads and what should be done in terms of building up a good set...

Of course, there are a few questions.. What kind of heads (ZE or 03) do you want to use?? How much do you want to spend?? What do you want to get out of your heads?? I am going to try to answer all of these questions in an easy to read manner, hopefully making this a good thread for many to start with... Preferably this can be made a sticky...

Lets start with the head similarities and differences.

1. 03 Heads have the same size HLAs, valvelocks, retainers, and springs, for both the intake and exhaust side.

2. ZE heads have larger stuff on the intake side. The HLAs are 1mm bigger. The springs and retainers are also bigger on the intake as well. The exhaust valvetrain is the SAME as KL03.

3. The valvelocks are the SAME for all heads, intake and exhaust. This is because all KL valves whether intake or exhaust, ZE or 03, have a standard 6mm stem.

4. Intake valves are larger than the exhaust valves, but, they are the SAME for KLZEs and KL03s.

5. ZE heads obviously have the larger intake ports, making them so popular.

Now, lets discuss the problems or downsides to each head.

1. KL03 heads have smaller intake ports, hence less flow. This is NOT a BAD thing, but its 1 downside compared to the ZE heads

2. KLZE heads have the bigger intake ports, but are harder to find and will cost you some cash... In the $400 range with cams, sometimes more or less

3. KLZE valve retainers have a tendency to crack and break, causing a valve to drop into the combustion chamber, essentially grenading the engine. This is caused by poor valvetrain design. There are two theories on this. The ZE valve spring pressure is 40lbs seat pressure and 140lbs open pressure. This allows for more valve float at high RPMs, where the ZE makes its power. This eventually causes the retainer to crack. Also, the springs were not manufactured well, and many have a burr that wears at the retainer until it finally cracks. This of course can occur at any RPM.

4. As said above, KLZE valve springs are softer. ZE seat pressure is 40lbs, and open pressure is 140lbs. On an 03, the seat pressure is 50lbs, and the open pressure is 150lbs.

[jon93PGT]

Ok, so now lets talk about what to do to fix these problems.

1. So we know that the ZE heads are more desirable due to their larger intake ports (more air allows for use of more fuel = more power).

2. But, we have to fix the retainer issues. There are two ways to do this. Aftermarket or swap over to the KL03 valvesprings and retainers. You must continue to reuse your ZE HLAs as the intake side are larger.

3. Or you can go aftermarket. All aftermarket parts are made on 03 sizes, so if you do this, you'll be using "03 size" springs and retainers anyway.. Again, you must still use the ZE HLAs. And as said before, valves and valvelocks are the same between both ZE and 03 heads.

4. In terms of aftermarket, there are 4 major companies. Ferrea, Interprep, Paeco, and CZT. Each has their benefit, lets investigate....

Ferrea- http://www.ferrea.com- Clearly this company has the most experience with aftermarket valvetrain products. They are the largest company and put out VERY nice stuff. For the KL engine, they offer a stainless steel valve, spring, and retainer, and chromoly valvelocks. The spring they use is a double spring. The downside of Ferrea? $$$ The full valvetrain kit listed above runs close to $1000.

Interprep- http://www.interpreptuning.com/- This company clearly has the MOST experience with the KL drivetrain. They have done extensive KL cylinder head R&D and have good products to boot. Alistair at Interprep is a great guy to talk to and will answer all of your questions. They offer products for the KL engine, but I am not too sure of the metals they use and what the specs are on their products.

Paeco- http://www.paeco.com/- I haven't done much research on this company, although the rumor is that they supply oversize valves. If you want to spend the extra money to machine your valveseats, this company will provide the valves. I do not know of the quality of their parts, customer service, etc...

CZT- http://www.cyborgzero.com/- Many know that CZT had some great ideas and good research, but I do not know how many sets they have or currently produce. They currently list a "Stage 1" valvetrain kit which includes titanium retainers and chromoly valvelocks. This is of course, 03 sized, so if you want to use this on your ZE heads, you'll need some 03 springs as well. They also used to supply a titanium spring package as well, which was part of their "Stage 2" package. I guess they do not produce these anymore as they are not listed on the current CZT site. Also, they are currently listing testing on new aftermarket KL cams. This company is cheap, but with a small background, and shortlived life on Probetalk, the customer service or product backing may not be what it is with the larger companies listed above.

So now its time to get the heads machined

1. What do you want to do and what is best for you?

2. The general process. One thing you will need to do first is obviously disassemble your heads. This will include removing the camshafts, and valvetrain. Many say that you MUST use a valvespring compressor to remove the springs. There is a much easier way to do so, requiring only a hammer, 17mm 1/2" drive socket and a 6" (or larger) 1/2" drive extension. Use the socket and extension and place the socket face on the retainer. Then smack the extension with the hammer. This will compress the spring long enough to let the valvelocks fall out. From here you can remove the valvelocks, retainers, and springs, as well as pull the valve out from the underside. Many say this is too dangerous, but I did it yesterday and it works just fine. You may or may not want to do this if you are reusing your stock valvetrain. I was doing it on junkyard heads, so screw it!

3. Now that you have the heads disassembled, replace the cam caps in THE ORIGINAL order they came off. The cam caps are labeled (numbers on one head, letters on the other) so its pretty hard to mess them up, but double check to make sure.

4. Now you're ready to bring them to the machine shop. What to have done. First things first, you'll want to get them acid dipped/steam cleaned/hot tanked. Many shops have a different term, but its all a cleaning of some sort. As well, you can get the heads bead blasted. This helps in the cleaning of the extra stubborn stuff, and gives them a "new" look when finished.

[jon93PGT]

5. From here, you'll need the basic machine work done. You'll of course want to get a valvejob and get the heads "decked". Decking is when they machine the head surface perfectly flat so that you get a better seal on the block. The valvejob is where they recut the seats so the valves seal better. You can get a 3 or 5 angle valve job, but for most applications, this is not necessary. The angled valve jobs are great for very high combustion chamber pressures (excessive boost or nitrous use) but for the moderate turbos and nitrous kits we normally run, its not needed. As well, angled valve jobs do not have the life span of a standard valve seat.

6. As well, you should probably get a pressure test done. This will check for any possible hairline cracks in the valves. This is very important especially if you do not know the condition of the heads. My heads came off a VERY strong running ZE, so I opted not to have the pressure test done.

7. As well, if you have more money than is good for you, you can have the combustion chamber volumes checked and matched... What is this? They seal the combustion chambers against a flat plexiglass surface and then fill the chamber with water using a pipet, measuring very precisely the volume of water that fills the chamber. This tells them if any chambers are slightly larger than another.... Is this necessary for most of us street drivers?? Absolutely not....

8. So, to recap, get em disassembled (or do it yourself), cleaned, bead blasted, decked, and a valve job.





Soo, that is the basics. Basically its what I've learned over about 3 weeks of reading, talking to people, SEARCHING on Probetalk.

If anyone cares to add to this, feel free. I also have the sizes of most of the valvetrain components, but I'm not going to post. You can search for "valve spring diameter" in the 2.5 Tech and Performance forum... You'll find the sizes posted by both myself and skelly.


Good luck and feel free to ask questions. My heads are just about done at the machine shop and Ferrea components will be in there very soon. Then Ludespeed turbo kit.....

[jon93PGT]

Holy crap that was a long post... I just started typing... It was so long I had to make 3 posts.. Dayum!!!

[El Nacho]

*sticky*

[jon93PGT]

heh, yeah, a mod has to see this first...

[pgtfreak]

I didn't even read it, but sticky for the long ass post!

[skelly]

I made my own valve spring compressor using a short section of pvc pipe with a section cut out of it and a 6" benchtop C-Clamp. The retainer clips come out easily with a magnet on a stick and there is no risk from bashing away on your head with a hammer. The going is a little slower, but as my father always told me, *shaking finger* "anything worth doing is worth doing right!" Of course the "right" way would be to use the right tool and purchase a spring compressor, but a suitable compressor can be improvised easily enough and still maintain a "right" disassembly procedure. Furthermore, this same procedure could be used to reassemble the valve train, something that no amount of hammer-bashing will do for you.

- SK

PS: props to Bobsprobe96 for pointing out this simplistically effective C-clamp compressor methodology.

[jon93PGT]

yes, that is another easy way to do the job...... But, like I said, I was doing this on a junkyard head just to get the spring and retainer... *shrug* I wasn't concerned with the head... Of course, I wouldn't be doing this on my own head..

[jon93PGT]

Ok, lets add some more info on whats available for aftermarket goodies..

Interprep- The offer a spring kit only. The springs are a chromoly steel spring, single spring style. The cost is $174 plus $15 or so for shipping... He said they frequently rev engines with these springs to 7800 all the time, without problems.. As well, he has two different cams, suited for NA engine setup. I am not sure what the lifts are as I am using ZE cams and doing a boost project anyway. But, they are available...

Ferrea- They offer a full setup, as stated above. I spoke with the engineer today and he told me the valve is a stainless steel one, and the springs and retainers are titanium. Again, the spring is a dual-spring style. He also said that the retainers and locks they make are designed for their spring only, although I'm going to call back tomorrow for exact dimensions and also get some pricing. He said they CAN sell stuff separate, but I'd have to call back tomorrow and talk to sales... I will do that...

I am also going to check into Manley valves... I forgot about them...

Stay tuned as I plan to make this thread grow.

[jon93PGT]

on another note... I stopped by the shop today.. My heads look brand friggin new!!

And they haven't even machined em yet. Oooh, I'm so excited..

[Bobsprobe96]

On Ferrea valves, the big deal with them is that they offer 1mm oversize valves for intake and exhaust. Both stock size and oversize are shaped to optimize flow, the intake valve is necked down in the port area. What I don't know is if the stock seats will allow the machining necessary for oversized valves, I will find that out with our local race shop. Does Ferrea make seats as well?

KL's have stainless (non-magnetic anyway) stock valves for the exhaust and our heads come stock with seats ground to 3 angles which is probably one reason they flow so well. The area right around the valve seat is the most critical for flow, so I have read.

I wonder why ZE retainers break when they seem to have less spring stress on them?

$7.25 a spring from Interprep...man you can't beat it!

Great thread Jon, good to get talking about this stuff.

[jon93PGT]

Hey Bob....

I stopped at my machine shop yesterday, and after spending some time looking at the valve seats, the machinist told me that there is NOT a whole lot of room for machine work, and we aren't even doing aftermarket valve sizes... Soo, I'd assume you'll be pretty pressed to get oversize valves in there... Let me know how it works out.

I do not think Ferrea makes seats for our application. I will be on the phone with them again today, so I will ask.

Yes, the stock valves are stainless.. Pretty nice too. The ones that came out of my ZE head looked great, so I was pretty happy. As for ZE retainers breaking, it is 1 of 2 reasons (or a combo of both I guess)...

1. The springs being softer allows for more valve float which apparently allows more slapping of the camshaft against the lifter. This smacking from the top as well as the smacking from the spring on the underside during valve float periods is very stressful on the retainers. Why did Mazda put a softer spring in? To keep the HLAs quieter. But, the downside is a retainer that is more prone to abuse, because lets face it. We all love to wind up those KLZEs clear to redline. They pull all the way..

2. The other reason they break is due to a manufacturing problem that left burrs on the ends of some of the valveprings. Why this only happens on ZE intake valves, nobody is really sure.. But, it could be due to the valve shape. The cross section of the 03 or ZE exhaust valves is a circle. If you cut the spring and look at the face of the cut, its circular. Well, on a ZE intake valve, it is square (or diamond shape due to the way its oriented)... This could be the reason that the ZE intake valves have burrs on them, or perhaps when machining this shape of a spring, the burring is more prevalent... I'm just speculating, but those are the only differences between the ZE intake springs and the other KL springs..

To recap, the spring is softer, and it has a different cross sectional shape.

Good luck Bob. When I get my heads assembled and back from the shop, I'll have to drive down and meet you and show you what I've got. From there you can see just what you want to do.. Or we can just compare whats done and oogle over fancy aftermarket goodies..

[skelly]

With only 1mm oversize, I suspect that there is enough meat in the stock seats to just machine them out without having to replace them. Another consideration that should be investigated is the geometry changes that may change the stock non-interference design into an interference design. If this changes it just helps to be aware of it before you beak something expensive quite by accident. I don't know what sort of clearances are between the piston at TDC and the fully open valve (think snapped timing belt, or belt replacement where the crank is turning independently from the cams - this is when you have an opportunity to smack a valve with a piston; worst case is a snapped belt when at speed).

[jon93PGT]

Skelly, another good point. Especially if you decide to run a high lift cam, this could definitely become a problem....

I will be running stock size valves with ZE cams, so I'm going to say I'm safe... My goals with my build were to fix the problems with the stock ZE heads (bad retainers) and do just a few choice mods to make the heads perform a little better. I'll be doing the Interprep springs, and hopefully the Ferrea retainers/locks. We shall see.