Hey all Maita GURU's, I was doing a bit of research for my upcoming ITB swap, and came across a link on DIYMIATA.com about using an factory exhaust cam as an intake cam. From what I gather it has about the same overall lift, just a bit more duration. The only reason I am asking at all is, I have a spare cam laying around. If this might be a cheap way to pick up a couple extra ponies and/or a few torques, i'd give it a try. Has anyone else tried it and dyno'd it for a real valuation. I don't expect much, but hey you never know. Also I do have adjustable cam gears, and figure if you fined tuned on a dyno playing with overlap you may be able to find a sweet spot.
Thanks
profeser
It's one of the big enthusiasms in the DIY crowd. Never tried it myself.
That seems odd, usually the intake has a longer duration and same or more lift.
In most cases I've seen like this its the Intake cam that replaces the exhaust cam, then a hotter intake cam goes in.
z31maniac wrote:
That seems odd, usually the intake has a longer duration and same or more lift.
In most cases I've seen like this its the Intake cam that replaces the exhaust cam, then a hotter intake cam goes in.
I think the ex. cam on the Miata has about the same duration but more lift than the intake cam.
Miata cam specs: http://www.solomiata.com/cams.html
It's the 1.8 BP8 that people are doing this two. I've got two or three extra cams in the garage, someday I'll give it a shot but I have a bunch others to test first.
I have done this! Hahaha first time i can say i did something new. Sa-weet.
Anyway. First off its a piece of cake to to. sorta. I had trouble at first re marking the cam sprocket but after a ton of re-measuring i got it. Swapping the cam and all that takes no time.
I did the cam swap before i drove a stock 1.8L Miata but i thought that it was really perky everywhere in the RPM range. Great pickup up top too. It idles like a cammed V8 and it had a shake to it. and the sound of the exhaust is a bit raspy and different. I loved it though.
I now am going back to a stock cam this season so ill see the difference. The idle is smoother i noticed.
If you want a cut exhaust cam and all that ill sell you my old setup. PM me
Keith & CarKid1989 thanks for the info. Glad to hear its at least noticable. I think I'll give it a try.
Keith when degreeing in the cams do I need to have the engine warm and the HLA's pumped up to be as accurate as possible? Or would just running the enigine just long enough to get oil pressure then shutting it down before the oil warms help to keep them pumped up longer with the cold thicker oil.
Thanks for the help all
the exhintake cam mod is confirmed to gain about 8whp after a protege (the originator of the mod) tuned it on a dyno using adjustable cam sprockets, the graphs are documented on a miata.net thread; if you google it you can see for your self. just thought i'd let you know if you havent already found the thread. i just grabbed the cam today from the junkyard and will soon have it in.
