...and I'm the counterpoint that lost my engine after 3 years with them....but lots of track miles at 7-8k rpm.
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Why don't more owners run cams?
- Thread starter L_RAO
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...and I'm the counterpoint that lost my engine after 3 years with them....but lots of track miles at 7-8k rpm.
Ah, but you didn't run the OEM valve springs, did you?
of course not.....comptech told me I needed thier springs:frown:
That is wild...you've got one owner who is reporting a ton of mileage and usage (17 years) without problems, and you've got another with only 3 years.
the springs are the issue, and for what its worth greenberets data point is an interesting one.
Did Comptech have their own springs made, or were they from some other manufacturer like Supertech? I'm looking at Supertech springs now.
Thanks,
Dave
Thanks,
Dave
Mac,
It is very likely that Comptech outsourced valvespring production and simply had it re-badged as their own brand. It happens all the time.
Though I doubt they'll ever tell you who the actual manufacter was, Web, Crower, Supertech and Ferrea would be places to start digging.
It is very likely that Comptech outsourced valvespring production and simply had it re-badged as their own brand. It happens all the time.
Though I doubt they'll ever tell you who the actual manufacter was, Web, Crower, Supertech and Ferrea would be places to start digging.
I'm trying to gather more information, so here is a public request:
If you have run any aftermarket cams, please chime in here.
Thanks.
If you have run any aftermarket cams, please chime in here.
Thanks.
For a little more history that will not be of interest to old timers. When Comptech designed their cams, they said anyway that they were doing the rebuilds on the Spice race cars and that they had learned a lot from the honda folks(spice engine reported 440hp) So when they come out with cams, one "wants" to assume that honda may have had a hand in helping them with the specs on the cams. And the specs are extremely important of course. So Car and Driver does an article on the stock car that i'm sure you have (right?) and they have a sidebar on Comptechs full house NA engine build with the cams. The car turned a meager 13.4 quarter. I was in that car twice and frankly it made a bit more 'waa", but sure didn't feel any faster than my IEH car, although it may well have been. Lots of folks had that test drive. And again, Comptec techs themselves were saying "less than 10 hp". For them to admit this to me likely means Much less. While Comptec said they did lots of dyno work on this, we have all been lied to by them. So there may well a bit more HP to be had, but it would take several sticks of different contours to be run on a dyno each of which would have to be tuned to perfection. So you would be talking tens of thousand of dollars in development for an individual to do. All for an engine that will never produce the torque of a 265 ci chevy smallblock. Witness this months 3.8 liter stroker making less than 300 ft lb. You can buy two Z06 crate motors for the cost of one stroker(with related parts). Sorry for the drift.
Yes, DA has used those in a few of their builds.
I'm waiting on my machinist to measure my old OEM valves to see if I can reuse them. If I can, I will probably buy new OEM valve springs (and keepers/retainers of course) and use those. After 20 years and 130k miles, the old ones must be a little compressed. I'll measure them and report the difference in my engine build thread.
I have the SOS FI cams as well as their Spring/retainer/lma sets
Yeah but 8hp is a 15 percent increase on a samurai :biggrin:
Would be like getting 35hp on an X
So, here is the latest on my quest for camshafts:
New Castings
Called the largest US manufacturers of camshafts - results:
1. Competition Cams - they will do the first run for $1500 per cam, and pricing goes down after that. I may do a group buy in order to subsidize costs.
2. Crane Cams - not interested
3. Crower Cams - not interested
Regrind/Hardweld
1. Web Cams - their cam expert says that the max lift he can achieve on the stock core is 0.420" of lift (hence the SoS profile). That's not nearly enough, based on my research and my builder's recommendations. He can hardweld, but that is $3800 for all 4.
I've also been talking to the owner of SVM, who makes billets for the K-series. He wants to get a hold of some actual NSX cams for R&D first.
New Castings
Called the largest US manufacturers of camshafts - results:
1. Competition Cams - they will do the first run for $1500 per cam, and pricing goes down after that. I may do a group buy in order to subsidize costs.
2. Crane Cams - not interested
3. Crower Cams - not interested
Regrind/Hardweld
1. Web Cams - their cam expert says that the max lift he can achieve on the stock core is 0.420" of lift (hence the SoS profile). That's not nearly enough, based on my research and my builder's recommendations. He can hardweld, but that is $3800 for all 4.
I've also been talking to the owner of SVM, who makes billets for the K-series. He wants to get a hold of some actual NSX cams for R&D first.
I have to confess that subconsciously I was leaving out adjustable cam gears because of their cost, and the cost associated with dialing them in correctly. Since they can't be dialed in with the engine in the car, an actual engine dyno, and removal of the engine becomes necessary.
"There's only one sure way to find out, install the cams and measure the clearances. Its very much the same thing as checking piston to valve clearance, just the methodology is different because you have to stop the cams rotating where they get closest to one another to take the measurement. On piston to valve you really want the valve reliefs to be too shallow to begin with if you're looking for the maximum in compression ratio. You check it at different lobe center settings relative to the valve to valve OK point and then machine the valve reliefs deeper until you're happy with them. The relative position of the cams to one another on that engine*is always fixed by the tooth pitch of the belt, so it can be done with the head on the bench with the valves facing you. The K-series is far more complex because of the VTC mechanism, which shifts the lobe centers of the cams relative to one another. I built a VTC adjustable valve to valve checking setup for the K-series a LONG time ago, and have made them for other engine builders as well. This is just normal shit when you're doing something no one else has ever done. I've been doing it all my life so to me it seems normal, but for most people its really scary.
You'll definitely need to use adjustable cam sprockets, and during the engine build the advance/retard on both cams relative to piston to valve and valve to valve will get recorded, and then not exceeded when the cam adjustments for getting the best HP are being made on the dyno.
This is pretty involved shit, but its nothing new or unusual.
Typical engine assembly on a K-series is about 50 hours. The C-series will for certain be more than that.
F1 engines are more like 220 hours. Having an old Cosworth DFV F1 engine rebuilt for vintage racing*routinely costs $50,000"
"There's only one sure way to find out, install the cams and measure the clearances. Its very much the same thing as checking piston to valve clearance, just the methodology is different because you have to stop the cams rotating where they get closest to one another to take the measurement. On piston to valve you really want the valve reliefs to be too shallow to begin with if you're looking for the maximum in compression ratio. You check it at different lobe center settings relative to the valve to valve OK point and then machine the valve reliefs deeper until you're happy with them. The relative position of the cams to one another on that engine*is always fixed by the tooth pitch of the belt, so it can be done with the head on the bench with the valves facing you. The K-series is far more complex because of the VTC mechanism, which shifts the lobe centers of the cams relative to one another. I built a VTC adjustable valve to valve checking setup for the K-series a LONG time ago, and have made them for other engine builders as well. This is just normal shit when you're doing something no one else has ever done. I've been doing it all my life so to me it seems normal, but for most people its really scary.
You'll definitely need to use adjustable cam sprockets, and during the engine build the advance/retard on both cams relative to piston to valve and valve to valve will get recorded, and then not exceeded when the cam adjustments for getting the best HP are being made on the dyno.
This is pretty involved shit, but its nothing new or unusual.
Typical engine assembly on a K-series is about 50 hours. The C-series will for certain be more than that.
F1 engines are more like 220 hours. Having an old Cosworth DFV F1 engine rebuilt for vintage racing*routinely costs $50,000"
Ponyboy, how many miles do you have on your setup? And when does peak HP occur?
Oh man, talk about clueless.
I get a call from someone at Crower. This is our actual conversation:
Crower: Yes, you interested in having some custom cams made?
Me: Yes.
Crower: What year, make and model is the car?
Me: It's a 1991 Acura NSX.
Crower: Does the motor have a code?
Me: Yes, it's a C30A.
Crower: Uh, is that the 1.8 or 2.2 liter?
Me: It's a 3.0 liter.
Crower: Oh, is that the B18 or H22?
Me: Neither, it's the C30A.
Crower: Does it have VTEC?
Me: Thanks, but I don't want you making my cams. Good bye.
Looks like custom-ground cams are going to be harder to make than I thought.
I get a call from someone at Crower. This is our actual conversation:
Crower: Yes, you interested in having some custom cams made?
Me: Yes.
Crower: What year, make and model is the car?
Me: It's a 1991 Acura NSX.
Crower: Does the motor have a code?
Me: Yes, it's a C30A.
Crower: Uh, is that the 1.8 or 2.2 liter?
Me: It's a 3.0 liter.
Crower: Oh, is that the B18 or H22?
Me: Neither, it's the C30A.
Crower: Does it have VTEC?
Me: Thanks, but I don't want you making my cams. Good bye.
Looks like custom-ground cams are going to be harder to make than I thought.
FWIW, Web Cams offers 3 different stages of cams. Sorry, don't know the specs, but I do own the Stage 3 cams. Sitting in a box.
Well, I spoke with Web and they told me on all their (regrinds) the most lift they can get out of the NSX cores is 0.420", which is WAY TOO LOW for what I'm trying to accomplish. I'm trying to get 0.472" (12.0 mm) lift, MINIMUM.
Your cams are just sitting in a box? How come you haven't installed them? They should come with a spec sheet...
Your cams are just sitting in a box? How come you haven't installed them? They should come with a spec sheet...
- Joined
- 29 May 2007
- Messages
- 438
Have you checked with Revolution in Japan. A friend worked there for Alkesan (sp) and drove their NSX. The have a big horsepower NA car. Here is a link to their website. The show cams under the NSX catalog / engine parts
http://translate.google.ca/translat...a=X&ei=BeZTUIXmJeOxyQG68YHYCA&ved=0CDEQ7gEwAA
http://translate.google.ca/translat...a=X&ei=BeZTUIXmJeOxyQG68YHYCA&ved=0CDEQ7gEwAA
Last edited:
- Joined
- 29 May 2007
- Messages
- 438
Here are the cam specs from their website:
【IN】60°-6.3mm、78°-7.3mm、65°-6.5mm
【EX】66°-6.0mm、78°-6.8mm、64°-5.8mm
【IN】60°-6.3mm、78°-7.3mm、65°-6.5mm
【EX】66°-6.0mm、78°-6.8mm、64°-5.8mm
Those specs don't tell us a whole lot.
Plus, for whatever reason, Google translate always kicks me back to the front / home page when I ask it to translate - I can't get any info on the engine parts page.
Finally, it is my understanding that those cams are regrinds as well.
Plus, for whatever reason, Google translate always kicks me back to the front / home page when I ask it to translate - I can't get any info on the engine parts page.
Finally, it is my understanding that those cams are regrinds as well.
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