cam questions
 

I am currently re-freshing an nb motor that I use on as my track-only car. I now have a couple of corners that I have to rev it to 7400 before getting onto the brakes (to avoid a quick up-shift into 6th), but of course the power drops off after 7000... so I'm just coasting and making noise. Ultimately, I'd like the power to continue till the 74-7600 range, with then some overspeed insurance, should I miss a shift.
The current set up is: 12-14# boost using MSM cams.

Q1: My camshaft experience has only been with v-8's and I'm having trouble transfering measurements into metric. I can do the math, I just am unfamiliar with the reference points. If my car were a small-block chev, then I know that I need about 10 more degrees of duration and that I need to keep the lobe centerline wide; like 115 degrees or so since it's turbo'd.

Things like advertised duration/ duration at .050 for a SBC cam I can grasp. However, I don't really have experience in the metric designations. Also, I've never before dealt with dual cams. I'm unsure if lobe separation is something that you adjust with adjustable gears, or if it can be easily gleaned from a cam card.

Q2: Worse yet, I don't really even know my starting point. While I can find raw numbers for the MSM cams on "search", I don't know how to make this info meaningful to me. I'm estimating 240 degrees or so duration @ 0.1? Unknown lobe separation.

Q3: At what rpm and at what lift are SUB lifter necessary. (as opposed to helpful)

Thx. I'm looking at a Kelford cam in the 264 duration @ 0.1 mm/ 9mm lift range vs a Kelford 272 @ 0.1/ 10mm lift range.

Subbed for info. I am also considering cams.

Also keep in mind that your turbo might be running out of air up there too.

I had a similar experience as you when I moved from the American muscle car to the Miata. My advice is to stick with the same language, and do business with an American company. I have done business with Web Cam, but there are other American cam companies that will build you a set. It will also be much cheaper than doing business with the Japanese offerings, and they work just fine. I can't argue with the results with my car.

How much cam you need depends on many different factors. Cylinder head modifications, whether you use a power adder, what type of power adder, and how robust the bottom end all play a factor. I have found the camshaft manufacturer to be the best source of information. I try to stick with a company that has done cams for leading racers. They will pass on the experience to you.

My personal opinion is the sooner you do SUBs the better. Even with stock cams, they will give you a tad more power and raise your valve float rpm. The are also less likely to spit out shims under high rpm. I have a tendency to make upgrades to the cylinder head before making other serious mods, and installed SUBs early in the game.

2Fast: thx. I have minimal cyld head mods so far. I plan to go with +1 intakes... still unckear about exhausts. Pocket port and "D" shape the entry to the intake with attention to the short radius. That's all SBC... I think/ hope it transfers to nb's. Forged rotating assy. 9:1 cr. Ms3 ecu and young smart motorheads that can tune like there's no tomorro.

aiden: gotta wonder if a case of pinot is worth a cat... I've got lots of great questions... Zero cats so far. So, hows the wine? Does the Mrs. like it? ,Cats, please....�� Garrett 2860

Hailey's in Nebraska for the year. So its going to have to age until the summer.

Cams:

Off the shelf options are Tomei, Maruha, CAT Cams. Somewhere in Canada. Webb cams.

I think you should call one of the above and state your goals, and let us know what they say :D

defiantly do shim under bucket conversion at the same time as the cams, you can take advantage of higher lift cams when you do that. Something in the 260 advertised range should get you a decent bit of power up top without making your car gutless in the mid range.

I have made the mistake of over caming a boosted car and the results are not great, you get a drag motor that makes wicked power in a 2000 rpm window.

Get adjustable gears and degree in the cams, this will allow you to adjust your cam centerline like a V8 but also adjust your lobe separation angle.

Web made the billet cams for my K24 motor and they are very high quality, I would see what they can do for you. When I had a BP I used Integral cams, but they have since gone out of business.

It *may* benefit you to switch to the Euro/Japanese square top manifold as it is known to help high rpm flow significantly.

Kelford told me they don't have blanks. You might wanna check with them.

As for shim under bucket, I run stock shims to 9K RPM on stock cams, with heavy double valve springs without issue. Nothing wrong with taking weight out of the valvetrain though, but since you asked necessary vs helpful, it's not necessary IMO. If you go with wild cams you may very well need them though. If I went with wild cams I'd do shim under bucket.

So, I just picked up my block from Loynings... bored, honed and mainlines cheched (@ temperature). Arnie shows me the process for setting up the cams on a 4 cam indy lights motor... he lost me on cam 2 ... so after that i just nodded and smiled. He told me that Web cams did a lot of his import work... so I called them and spoke to Faith. She thought that tbe oem was approx 255 degrees intake and 272 exhaust. She's quite astute in her knowledge base and asks me to send in my current cams, where they can assess the present lift/duaration/etc and then give me recommendations based upon my goals. They preferred to weld up and then heat treat rather than use mazdamotorsports billets as they felt that they would have better control of the heat treated/hardened layer. I wish that I would have asked if she was single... anyone with reservation here? I may ve in love.

Solomiata : Engine : Camshaft specs

https://cimg6.ibsrv.net/gimg/www.mia...d408e3296f.png

MSM has a BP5A intake cam.

So .349" Lift and 251 duration.

BP5A Mazdaspeed intake cam

251 advertised, or 251 @fifty? I'm gonna send it in to be measured, then welded/ground ... unless you've got a replacement cam to swap for an msm.... no sense on wasting it if it has usefulness.

I do have a spare MSM cam. It has a bit of surface rust but if you are welding and grinding it it should be fine.

Shoot me a text.

Mazdaspeed blanks are long gone, unless you bought early. I'm rather surprised they would rather weld over than grind fresh and heattreat. https://cimg5.ibsrv.net/gimg/www.mia...0eb520df92.jpg

file:///C:/Users/craig/AppData/Local/Temp/datasheet3701406.pdf

Cat cams recommended this. It doesn't look very big at all. I'm unclear if it's even much bigger than the msm cams I am currently using. Comments?

Woops, that link didn't work. Basically, the cam is: 258 I/ 240 E @ 0.1mm; 230 I/ 214 E @ 1.0mm; 9.95/9.25 lift; 110 I/ -120 E centerlines.

By the solomiata link that Adain posted, it looks like the 99-00 bp (non-msm) cams were: 209 I/ 215 E @ 1.0mm; 8.58 mm lift. I'm still having trouble finding the measurement reference for the msm cam... is it advertised? @ 0.1mm? @1.0mm? or, @ .050"?

Your attachment didn't upload correctly. Forward it onto me in an email?

That's a fairly large cam.

Is it? I still haven't figured out what the oem msm cam profile is. One reference is 251 duration (MSM Intake); but where on the ramp is it measured? So, I hope to find a local shop that has a way to measure these (maybe a program like a Cam Doctor set-up).

I am sincere about wanting to know the rpm limits of the turbo-NB motor, as I have ruined many engines over the years, mainly due to exceeding rpm limits. At one point I had the opportunity to get good advise and analysis from a GM engineering group. They had a program to estimate bearing loads. This took into account stroke, rod ratio and then used compression/ cam profiles/ timing to calculate cyld pressures. They showed me that I could run my 333ci motor well up to near 9k, while the 410ci motor would only survive under 7600.

It's my feeling that most don't cam the turbo-miata because it's expensive and not a lot of "off the shelf" availability. If the advise that I'm getting is "keep the oem cam because the motor won't last above 7k", then I'll do that. But, if I'm keeping the oem cams merely because it's convenient, then it seems that I might be leaving some torque/power on the table. But, I do need to know my rpm ranges before I can ask a cam grinder to make me a profile. I'm hoping that 4500-7600 is a reasonable range.?. Or, as previously suggested, I can change my gearing to work with a lower rpm range.

I run maruha 264/264. Unless you're OK with some lag, running above 4k RPM or going to remedy with wet-nitrous, I suggest shorter duration like the 252/256 tomei or maruha cams. I'll be making the switch when I have cash and time to pull my head and gap things again.

I still don't have a local dyno chart - Wish my local guys weren't toolboxes.

I did just finish reading up on your "engine build" thread. You have made some serious power with that motor. ...more than I will likely need. Your 4K T/HP numbers are where my current motor peaks. I will take your suggestion and try to keep the cam on the smaller side. Nice build!