Want a "Baller" valvetrain assembly?

I watched the teardown of a Porsche 911RSR engine a few years ago (sorry no pictures), the cam and lifters looked similar to this...



Inverted radius cam profile

[IMG]https://www.miataturbo.net/attachmen...ine=1368049417[/IMG]

Keyed lifters with ramps on the crown.

[IMG]https://www.miataturbo.net/attachmen...ine=1368049417[/IMG]

I swear they must engineer some valve bounce in that thing. How the heck does the valve not launch off that nose?

Bounce would lead to component failure.

They actually lift the valve almost to the point of complete valve spring compression (about .050 clearance). So at max lift the spring physically cannot compress any farther.

Ahh that makes sense. Very cool!

I've got some CatCams here in the UK after contacting them for some clients cars.

I used some of their profiles on a Peugeot 106 I had way back when, it had a decent compression ratio for NA so responded great to a cam upgrade. I'm putting a set of their camshafts in a B6 head for my daily atm along with their own SUBS and spring upgrade. The car currently runs ITB's, long branch primary's and an unrestricted exhaust so hopefully will show a gain!

The specs of the cams are:
- intake: 277°@0.1mm/243°@1.0mm/12.01mm/3.19mm@106°/vc 0.250mm
- exhaust: 269°@0.1mm/235°@1.0mm/11.51mm/2.67mm@-106°/vc 0.250mm

which will hopefully give a bit of a gain on my standard bottom end, I'm planning on running a turbo at a later date so will play with cam timing when the time comes.

I'm lucky enough to have a dyno here on site so will update with some RR graphs on the same setup stock cams vs the above.

Dan

Not true.
Its not unusual for engineers to design a profile coupled with the right valve spring to utilize "valve lofting", in which at a tuned rpm range the valves will "loft" off the profile. Its a way to get variable lift and duration.

It has proven to lead to accelerated wear on the cam and lifters, too much so for OEMs to utilize in street cars, but its plenty reliable for race engines that get torn down frequently.

The lift on those cat cams is really up there, what's the upper limits of a 9:1 block with a 99 head?

Limit for what?
Non-interference
Valve-piston contact at zeroed cam timing
Flow available in a stock head
Reasonable setup with available spring kits
...

11mm starts to be a lot on the BP IMHO (for a number of reasons).
Unsure what clearance there is on a zeroed cam with 9:1 Cast Mazda Pistons on an undecked block.

Exactly. Way too many variables to work with. Some examples that need to be considered:

Lifter bore to camshaft interference.
Reduced based camshafts
Decked heads
Decked blocks
Non OEM pistons
OEM piston design changes. (94 vs 96 vs 99 vs 05)
oversized valves
Cut valve seats

I guess I would say when does the engine become interference? Assuming all else is unchanged from a blueprinted standpoint.

Much more than 9mm lift and you will need to cut the lifter bosses and get springs.

Digging up an old thread I know but those cams I quoted above turned a car with ITB's on a stock head from 100wbhp to 118wbhp with a lovely torque curve. I'm rebuilding the car atm with a VVT engine that will have some custom cams.

Daniel

My intake cam has .495 gross lift. On BP4W head. Im running off the shelf weisco pistons. I had to cut clearance for them to spin. Im running super tech springs with no inner springs.

Stock VVT cams are 9.4mm ;) VVT head castings will take 10mm cams on the intake side, but not on the exhaust side. I seem to remember the 6D castings having more clearance than the 4W castings did on the intake (the exhaust cams are all the same, but 4W lift is only .326 to the 6D's .370), but that might just be in my daydreams.

You don't have to keep the 36mm base circle.
More space for the spring/lash setup is another advantage.

does any one have experience with re-grinds? Before i put my engine into my new chassis I'm going to be replacing the Integrals with something more tame, Im either going to contact Web or Kelford. Im a little skeptical about having web regrind my stock cams vs a new cam from Kelford. But i like the idea of using someone in the US to do my cams so i can stay in contact with them easier.

I will be doing something in the 220 duration @ .050" range and as much lift as i can run with out getting really extreme with the ramps.

Regrinds are much better than they used to be but for me I always order a fresh cam - there's only one argument then if something fails.

where can you find cam blanks for bp4w heads?

I went with cat cams for my custom cams. I can't say enough good things about them. They kept in constant contact with me throughout the whole process and will make you a custom billet cam with whatever possible specs you ask for. Matthew is the guy you want to talk to over there. Great customer service.

You live in the USA? How long did it take to get the cams?