http://www.superchargerperformance....head-porting-for-lower-boost-and-higher-power
Interesting article.
Interesting article.
Anyone have cylinder head work done?
- Thread starter L_RAO
- Start date
For what it’s worth: I had Comptech modify my cylinder heads back in the spring of 1995. They ported and polished the heads and milled out the valve spring seats so that the stock valve springs would work with their higher lift camshafts without binding. My engine has been running in that configuration up to 8000 rpm on the Autobahn since then without any problems whatsoever. I never measured how much the heads flowed before or after Comptech’s work but the car is fast and I’m happy with their work.
From what I’ve gathered, at some point Comptech stopped milling the valve spring seats deeper so that the stock valve springs would work with high-lift camshafts and instead they started leaving the valve spring seats as they were and sold different valve springs instead. Maybe that wasn’t such a good combination.
FYI on RLZ:
I emailed them (there's two guys that work out of the shop - one on cylinder heads and the other on total engine builds) on engine work for my NSX. Neither contacted me back.
They're only 1.5 hours drive (one-way) from me. Still contemplating on whether or not to take them personally up there and see what they could do. Their reputation is awesome, but the internet is full of stories on how long it took them to do their work (if they'd even accept your work).
That's too bad.
Dave
I emailed them (there's two guys that work out of the shop - one on cylinder heads and the other on total engine builds) on engine work for my NSX. Neither contacted me back.
They're only 1.5 hours drive (one-way) from me. Still contemplating on whether or not to take them personally up there and see what they could do. Their reputation is awesome, but the internet is full of stories on how long it took them to do their work (if they'd even accept your work).
That's too bad.
Dave
Dave,
Did you ever get a hold of anyone from RLZ?
Did you ever get a hold of anyone from RLZ?
Nope. I gave up since I will be FI and porting isn't a necessity. But if you want to stay N/A, I think they have the best reputation for Honda heads - If you can get a hold of them.
Maybe start a thread in the SouthEast forums for a local Charlotte person to swing by and talk with them. I don't think they answer the phone or emails.
Dave
Maybe start a thread in the SouthEast forums for a local Charlotte person to swing by and talk with them. I don't think they answer the phone or emails.
Dave
What do you know? I got a response from them:
264 seems little high
what kind of dyno was that ?
To hit 300 whp porting and ITBS or some kind of new manifold would be required
Porting NSX heads starts @ $2000
264 seems little high
what kind of dyno was that ?
To hit 300 whp porting and ITBS or some kind of new manifold would be required
Porting NSX heads starts @ $2000
Agreed.
In my engine build (which I'll create a separate thread with pics and details once it's completed) my engine builder (who's been in business for 43 years and have seen just about every engine out there) did remark how my NSX port design is one of the best that he's seen.
He mentioned that from his years of experience in porting that there isn't much to be gained in porting, but did recommend that I clean up some areas where the cast the the valve seats were not a smooth transition and to sharpen the area where the air the manifold "Y" to the individual combustion chamber.
Once he does that I'll send the head and manifold off for ceramic coating.
Weren't you the one that posted the supercharged article on the top of the page?
http://horsepowercalculators.net/af...head-porting-for-lower-boost-and-higher-power
Larry (Endyn) quoted me that their "small" port configuration, they are making +25 cfm (intake) and +35 cfm (exhaust) over stock. Those gains are "in regions or real valve life, not 0.500" or higher lift."
Based on the article above, and this one:
http://www.pumaracing.co.uk/Exvalve.htm
+25 cfm and a +1 mm intake valve should potentially be worth up to 18 wHP, more with bigger cams and/or more compression.
At $3500 (estimate) for head work, R&R labor, etc. this would be closer to $200/HP. I'll have to kick this to the back burner for now.
I've always wanted to know if we could adapt the later Honda variable cam timing to our cars.
It's a Honda product on almost all of their vehicles now. The gains could be huge on both N/A and F/I.
Here's a thread I started on it awhile ago. I think this sounds like a good next project for L_RAO and ProSpeed :wink:
Dave
http://www.nsxprime.com/forum/showthread.php?t=152764
It's a Honda product on almost all of their vehicles now. The gains could be huge on both N/A and F/I.
Here's a thread I started on it awhile ago. I think this sounds like a good next project for L_RAO and ProSpeed :wink:
Dave
http://www.nsxprime.com/forum/showthread.php?t=152764
Nice idea, though I think we'll see the following:
Before we see a VTC conversion kit!
- Laser ignition conversion kits
- Direct injection conversion kits
- Toda cam dyno results (my current unicorn)
- The new NSX powerplant swapped into an NA1/NA2
Before we see a VTC conversion kit!
From my research in the LSx folks is that NA cams increase overlap of the intake and exhaust ports to take advantage of increasing the scavenging effects. It's less efficient in MPGs and more polluting, hence usually a problem with CA emission laws.
Blower cams are suppose to reduce, if not eliminate overlap, which should increase MPG efficiencies and reduce emissions. Also, by reducing/eliminating overlap u can have more of the charge fill the combustion chamber, which in term would also bump up the effective displacement or compression ratios.
Which is the beauty of VTEC. A bigger VTEC lobe wouldn't really affect emissions, since smog testing is done on the small lobe, nor gas mileage. Of course if you spend a lot of time north of 5000 RPM, one's gas mileage wouldn't be great no matter what.
Which is counteracted by the right foot magically getting heavier...:biggrin:
Remember, a bad (shaped) valve job can screw up an otherwise decent port. 5, 6, 7 or even more angle valve jobs are not that uncommon anymore. Complimentary accents on the backside of the valves are also required to make an efficient window from low to high lifts. It takes special tooling and an experienced individual, but that's where I'd look for more power with the NSX heads. Anyone using basic stones to cut the seat angles will no doubt result in LESS flow than stock (both int and exh), even with a so called "Port job". A good seat/valve design will improve flow and reduce reversion at the same time.
I would contact Tony @ Comptech or Shad @ Driving Ambition. Shad was going to do a cool NA 3.5-3.8 engine job which included CNC porting on the heads and billet "1 off" cams. If you want any noticeable difference you have to change the cams, pistons etc and spend a LOT of MONEY.
Here is a link to something that Comptech built. 500 HP 3.8 NSX type engine.
http://www.comptechusa.com/Grand-Am - Beyer Racing Honda DP Set for Laguna Seca.pdf
Here is a link to something that Comptech built. 500 HP 3.8 NSX type engine.
http://www.comptechusa.com/Grand-Am - Beyer Racing Honda DP Set for Laguna Seca.pdf
I have been going back and forth with another reputable Honda head porter...they are interested in doing the work simply for marketing purposes.
After R&D they will CNC digitize the port job, so that anyone who wants the porting done after the fact can ship their heads to them.
Based on their experience with the B- and K-series heads (they do about 150 K-heads per year, and 100 B-series heads per year), they don't see why their port job couldn't make 18-25 wHP on an NA motor, and 40+ on a FI motor.
They were shocked at the (poor/non-existant) camshaft selection for our cars.
After R&D they will CNC digitize the port job, so that anyone who wants the porting done after the fact can ship their heads to them.
Based on their experience with the B- and K-series heads (they do about 150 K-heads per year, and 100 B-series heads per year), they don't see why their port job couldn't make 18-25 wHP on an NA motor, and 40+ on a FI motor.
They were shocked at the (poor/non-existant) camshaft selection for our cars.
I tend to agree here.
For my engine build I felt that a 3-angle valve job and a port clean-up where the casting surface is deburred and smoothed out and the vanes that seperate the intake gases to their respective valves sharpened up where I cut my finger on one of them as I was digging around in my heads admiring the port walls is suffice.
My engine builder said that unless I'm willing to go past 1 bar of boost it didn't make much sense to enlarge or change the port shapes.
Less than a 1 bar of boost + enlarging the ports can slow down the port velocities.
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I've recently started looking into this myself and am hoping to find some info.
I've recently started looking into this myself and am hoping to find some info.
Here is an "update" on what I've found, so far, information-wise:
1. Honda heads flow great, but if the C is related to the B (which it is), then intake ports should flow somewhere in the high-290 cfm range, and the exhaust ports stand to gain more from porting than the intake ports, though both will gain from porting. The intake side really likes a good valve job, and that alone can be worth 30 cfm. (On the K-series, most porters simply leave the exhaust ports along because they have found that most port jobs decrease flow volume/velocity).
2. C30 heads have 35 mm intake valves, and 30 mm exhaust valves. The intake valves can be increased to 35.5 mm without too much work.
3. C32 heads have 36 mm intake valves, and 30 mm exhaust valves. The intake valves can be increased to 37 mm without problems. One vendor has 37 mm intake valves on the shelf, ready to go.
4. Both C30 and C32 intake port flow would benefit from "unshrouding". However, without new pistons, you would actually lose compression because you have to remove combustion chamber material in order to unshroud the valves, which would negate any power you made from increased airflow. Bottom Line: Unshrouding is beneficial, but only as part of a full build (i.e., higher compression pistons).
5. Both C30 and C32 heads have dual valvespring setups.
1. Honda heads flow great, but if the C is related to the B (which it is), then intake ports should flow somewhere in the high-290 cfm range, and the exhaust ports stand to gain more from porting than the intake ports, though both will gain from porting. The intake side really likes a good valve job, and that alone can be worth 30 cfm. (On the K-series, most porters simply leave the exhaust ports along because they have found that most port jobs decrease flow volume/velocity).
2. C30 heads have 35 mm intake valves, and 30 mm exhaust valves. The intake valves can be increased to 35.5 mm without too much work.
3. C32 heads have 36 mm intake valves, and 30 mm exhaust valves. The intake valves can be increased to 37 mm without problems. One vendor has 37 mm intake valves on the shelf, ready to go.
4. Both C30 and C32 intake port flow would benefit from "unshrouding". However, without new pistons, you would actually lose compression because you have to remove combustion chamber material in order to unshroud the valves, which would negate any power you made from increased airflow. Bottom Line: Unshrouding is beneficial, but only as part of a full build (i.e., higher compression pistons).
5. Both C30 and C32 heads have dual valvespring setups.
I'm not sure if I mentioned in this thread or that DIY engine build thread, but when I upgraded my valves to the lighter and stronger Ferrea valves my engine builder told me to get the Tulip shaped exhaust valves since they scavage the exhaust better than the nail head shaped valves (which are cheaper to make).
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Not to say that your builder is wrong, but the guy I will use will NOT touch Ferrea. He pointed me out to a superior valve company. But yes, your builder's suggestion on valve stem shape is a good one.
He also showed me, first hand, the difference between ARP and a "real" fastener company.
He also showed me, first hand, the difference between ARP and a "real" fastener company.
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