I'm in the process of designing my engine build and am considering replacing the intake and perhaps the exhaust valves in the interest of greater flow (undercut for the intake) and valve weight reduction.
How much do the factory NSX intake and exhaust valves weigh?
- Thread starter BATMANs
- Start date
I don't know which company makes their valves. Although I suspect that it's from Supertech.
I've used the Ferrea for the GTO build and the reason why I choose them is that the 1000HP+ MKIV Supra folks seem to prefer them over the other brands for the fact that the Ferrea valves forged alloy will tend to bend instead of the head breaking off and bouncing around in the combustion chamber - creating more damage in the event that you mis-shift/over revving and the valve and pistons were to "kiss" each other.
The other boat/car forums seem to prefer Ferrea valves as well:
http://www.performanceboats.com/dyno/84984-when-go-inconel-valves.html
http://www.audizine.com/forum/showthread.php/374981-Ferrea-or-supertech-valve-spring-set
http://www.importatlanta.com/forums/showthread.php?291678-gsr-valves....-supertech-or-ferrea
http://forums.evolutionm.net/evo-en...rtech-vs-ferrea-either-better-than-other.html
http://forums.vwvortex.com/showthread.php?5302583-Valvetrains-Supertech-vs.-Ferrea-school-me
Also Ferrea is the only undercut valves that I know of that doesn't cut the stem portion which removes stem material that creates a weaker area on the stem. Ferrea squeezes the neck a little further more to create the undercut effect. The benefits is that you don't loose material and preserve the metal grain.
I just got off the phone with Ferrea and here are the weighs for their Superflo (undercut) solid stem forged valves:
Intake: 54 grams
Exhaust: 43 grams
Last edited:
It's a lot of complicated math, science, and experimentation that we'll probably never figure out!
Undercutting may not be the best thing to do. Also, squeezing the neck like Ferrea may not be the best either, as it's a balance of radius, angles, flow areas, etc:
http://www.gofastnews.com/showthread.php/1247-porting-school-8-optimal-port-areas.html
Dave
Undercutting may not be the best thing to do. Also, squeezing the neck like Ferrea may not be the best either, as it's a balance of radius, angles, flow areas, etc:
http://www.gofastnews.com/showthread.php/1247-porting-school-8-optimal-port-areas.html
Dave
Last edited:
Make sure you post the results in the "unofficial weight reduction thread"
:biggrin::biggrin::biggrin::biggrin::biggrin::biggrin:
:biggrin::biggrin::biggrin::biggrin::biggrin::biggrin:
Dave, I totally agree. The LSx engine builders tend to agree too. But most of those were on NA engines. For blown engines. Especially ones that run high boost the undercut seems to make more sense. Besides Ferrea is not as aggressive in their "undercut" diameters.
My engine builder has access to a flow bench shop and what would most likely happen is that he will get a set of valves for one chamber and compare them to the OEM valves in flow tests.
Cool. When do you think you'll be doing this? I'm taking my engine apart this Winter and still don't know what I'm doing for the heads yet. With FI, I'm trying to optimize the bang-for-the-buck and will probably keep my OEM cams. I'm not sure what to do on the valves. I will probably keep the exhaust valves if they're still within specs, but am undecided if I want to do the same with the intake valves too, or upgrade those to the larger '97+ ones. I mean, a 1mm increase in intake diameter only increases flow area less than 6%. But then again, it's only $200 :wink:
Please let us know your results!
Dave
I'm going to start on this in the next week or so. And the goal is that have it finished by the end of January.
I'm keeping my OEM cams.
I'll share my discoveries so stay tuned...
I checked with Shad and Jon Martin about installing larger intake valves in my cylinder heads. Both agreed that if I keep the cylinders’ bore at 90 mm (stock 3.0 NA1), I should stay with 35 mm intake valves. The edges of 36 mm valves (like the ones the 3.2 NA2s use) get so close to the cylinder walls in 3.0 liter engines that they start shrouding the flow.
If it's valvetrain weight reduction you're looking for, then consider the Comptech/CT or Toda cam gears. Both are much lighter than stock, and will reduce rotating mass within the valvetrain.
As an FYI, Ferrea also offers titanium retainers.
As an FYI, Ferrea also offers titanium retainers.
I hear that titanium valves and retainers are not a good idea for long term use since they tend to wear faster than a good steel alloy.
t
t
I hear this stuff too. Then you talk with engine builders and they say they don't have any problems with the particular brands they use. Couple that with the fact most NSX owners don't share a lot of this pertinent failure information publicly, and I'm really confused on what to do
That's why I'm thinking I'll just stick with OEM valves, upgraded '97+ dual valve springs, new OEM retainers, and new '97+ LMAs. I guess for non-racing applications you really can't go wrong with it....
Dave
Another option is to have your cylinder head guy/engine builder basically do what Spoon does on their engines: shave off all casting imperfections off all valvetrain pieces. Spoon calls it "blueprinting" in their catalogs.
I hear this stuff too. Then you talk with engine builders and they say they don't have any problems with the particular brands they use. Couple that with the fact most NSX owners don't share a lot of this pertinent failure information publicly, and I'm really confused on what to do
That's why I'm thinking I'll just stick with OEM valves, upgraded '97+ dual valve springs, new OEM retainers, and new '97+ LMAs. I guess for non-racing applications you really can't go wrong with it....
Dave
If u think about it, Titanium isn't always stronger or harder than steel. You use hardened tool steel to cut titanium. Not the other way around.
I would probably go with beehive over dual or triple coil springs.
That's what I did with the GTO build and have been very happy with it.
Because the top diameter of the beehive spring is so much smaller than a conventional spring, and no secondary step for an inner second spring is needed, the retainer weight drops by a little over half. This brings the retainer weight from about 34 grams to 16-17 grams, making a cheap steel retainer for a beehive spring a gram or two lighter than a titanium retainer for a conventional spring.
This brings the over-the-nose weight savings for the beehive springs up to over 50 grams, which is greater than the typical difference between a steel and TI valve. If the budget allows and you want to go with TI retainers then.
Spring surge is a conventional spring’s #1 problem. Spring surge is the major driving force behind the adoption of air springs on those 19,000 rpm F1 engines. If a super spring is possible then the primary goal is to find a way of eliminating surge without the need to introduce the ultimately destructive element of friction damping into the equation. The beehive spring does just that.
anyone know what the factory valve angles are? The OEM exhaust valves look to be nail head and I was told that a tulip exhaust valve may be better suited in exhaust scavenging effects.
Any thoughts?
Any thoughts?
I'm going to see my shop today around lunch to discuss the valves.
I did some research and it appears that in most other engine applications 30º angle plus the undercutting and swirl-polishing will add approximately 15% more airflow at higher rpms, which equals to about 2-3 more horsepower to a garden equipment engine that originally had a 45º angle on the intake valve and seat for example. And for the exhaust gases to exit the combustion chamber quickly, grind a 45º/46º angles respectively, and undercut the exhaust valve head.
Honda uses the 30-45-60 degrees discreet angles configuration for their valve seats in their performance-oriented cylinder heads, as seen in the GSR, ITR, and CTR. They are called "discreet" because they stand out on their own with distinct sharp edges or borders and are not blended smooth into each other like radiused seat angles seen in domestic heads. It's important to cut the 45 degree angle valve seat surface location precisely (using dye to mark if the seat sits properly).
On the cylinder head, the 30 degree is closest to the piston or combustion chamber side and is called the "top cut". Next is the "seat angle" proper which matches up to the valve face’s 45 degree seat angle. The 60 degree angle below the seat angle is closer to the intake port/IM and is called the "throat cut".
I'll see if that is what he's seen with other builds.
I did some research and it appears that in most other engine applications 30º angle plus the undercutting and swirl-polishing will add approximately 15% more airflow at higher rpms, which equals to about 2-3 more horsepower to a garden equipment engine that originally had a 45º angle on the intake valve and seat for example. And for the exhaust gases to exit the combustion chamber quickly, grind a 45º/46º angles respectively, and undercut the exhaust valve head.
Honda uses the 30-45-60 degrees discreet angles configuration for their valve seats in their performance-oriented cylinder heads, as seen in the GSR, ITR, and CTR. They are called "discreet" because they stand out on their own with distinct sharp edges or borders and are not blended smooth into each other like radiused seat angles seen in domestic heads. It's important to cut the 45 degree angle valve seat surface location precisely (using dye to mark if the seat sits properly).
On the cylinder head, the 30 degree is closest to the piston or combustion chamber side and is called the "top cut". Next is the "seat angle" proper which matches up to the valve face’s 45 degree seat angle. The 60 degree angle below the seat angle is closer to the intake port/IM and is called the "throat cut".
I'll see if that is what he's seen with other builds.
Last edited:
Anyone know if the NSX heads are more like a D or B series head in terms of port design?
B-series.
This is part of my build.
Another FYI: the record setting FXMD NSX had its cylinder heads done by Portflow...
Apparently SOS has/does use them too:
http://www.portflow.com/clients.htm
I've tried contacting RLZ Engineering numerous times, but they don't return calls or emails. Oh well. They're close enough drive to me that I could just run up there, but internet searches show this is common for them. Even if they're the best, it seems like a problem waiting to happen.
Dave
http://www.portflow.com/clients.htm
I've tried contacting RLZ Engineering numerous times, but they don't return calls or emails. Oh well. They're close enough drive to me that I could just run up there, but internet searches show this is common for them. Even if they're the best, it seems like a problem waiting to happen.
Dave
Batmans - What did you end up doing for your valves?
Are the Supertech valves the only aftermarket ones available for us?
Thanks,
Dave
Are the Supertech valves the only aftermarket ones available for us?
Thanks,
Dave
Funny you should ask since I should be expecting them today or tomorrow.
I went with the Ferrea Valves from the cheapest vendor.
$535 for the full set of 24 valves with shipping included.
They are the best in the world from my research.
The key difference with them is that should u make the mistake of mis-shifting and the valve and piston were to make contact, they would bend instead of breaking off, which would do more damage.
Both intake and exhaust are undercut and should be a few grams lighter.
I went with the Ferrea Valves from the cheapest vendor.
$535 for the full set of 24 valves with shipping included.
They are the best in the world from my research.
The key difference with them is that should u make the mistake of mis-shifting and the valve and piston were to make contact, they would bend instead of breaking off, which would do more damage.
Both intake and exhaust are undercut and should be a few grams lighter.
Pretty.:biggrin:
