[Caldera]

So yeah. It took a day, but I got the Exhintake completed.

Whoa. It's a definately noticeable, nice change. There's a linear pull to the top of the powerband now that didn't seem to be there before. It feels less... peaky. Idles a shitton better too. Sounds slightly different.

There were a few things I somehow missed out on before I started, and things I'd do differently next time.

The cam lobes keep the cam from sitting level when you cut it. I'd make sure to brace the cam differently next time, as mine has a slight angle to the cut I made to the cam. Make sure that you have access to an abrasive saw and a grinder to clean up the back edge of the cam.

Don't use anything less than a bandsaw or abrasive saw. They act like a hot knife through butter.... but I imagine that this'd be a stone cold pain in the ass with a sawzall or a hacksaw.

Since you're going to be completely pulling the front of the motor off, it's a good time for a fresh timing belt/waterpump if you need 'em. My belt has under 10k on it, so I didn't need to bother.

When you drill a hole in the gear, make sure you drill it slightly towards center compared to the outer edges of the slots, the pin is about 1mm inwards from the outer edge of the slots. Whoops. Diegrinder is my friend.

Assembly lube, assembly lube, ASSEMBLY LUBE! I had a ton of oil on the cam, but still wish I'd used some.

Make sure when you say you have an exhaust cam and gear and are going to do this project... that you actually HAVE a gear, and your cam isn't wiped like mine was. Whoops. 2 for 2, had to scrounge/buy parts.

The car feels like it'd run high 15s in a straight line now, but I do have some supporting modifications.

Engine "mods": Fidanza flywheel, Unorthodox UDP, Racing Beat intake, Racing Beat header, Racing Beat exhaust, redrilled stock gear and no cat. Now featuring Exhintake cam. Basically a junkyard longblock, with boltons.

Costs:
Gear: 15.00 (thanks Bill!)
Cam: Free (and I guess whatever it costs to replace it since i had to bum one)
Machine work to gear: 60.00.

...so for 75.00, i got a noticeable change to the car for the better. I just wish I'd had a chance to dyno it before I did the install.

 

[freedomgli]

Awesome! I know you were trying to get this installed last night. I'm happy to hear everything went okay and made positive results for you.

 

[Caldera]

Yeah, i got to it around 3-4am, and found the bum cam, i restarted around 1130 this AM, helped Ben reseat the Enthusa for a bit, went to an S2kI meeting, and then finished retiming it. Had I not had to time it twice, it was only about 4 or so man hours of work, slacking at it.

 

[slydin miata 619]

hmm i've been wanting to do this for a while now...how much WHP do you think you got from it? and is it worth the trouble?

 

[Agent935]

Awesome! glad to hear it was worthwhile!

 

[Bryan]

Good stuff. The mod, if dyno'ed is probably worth about 5-10rwhp, I'd bet. The benefit is that it's over the entire powerband, which is probably what makes it so "noticeable."

Good job

 

[slydin miata 619]

hmm i think it's time for me to go to the junk yard and get an exhaust cam...umm oh yeah heres a good question...should i get a new valvetrain with this

 

[Guest]

I always thought that the cam profiles were the same for in and ex, the only difference between the two was the spline for the CAS. Was I wrong?

:-k

Please explain how this mod is any different than using an adjustable gear.

~Bill

 

[Caldera]

Nope, they're different profiles.

http://members.aol.com/solomiata/cams.html (see 94-97 for my case)

Normally the Exhintake uses an adjustable gear, but I was cheap and bought that gear from you, had it drilled at the required point of adjustment, and just installed it there.

 

[Agent935]

here's a cheap place to get adjustable cam gears if you want to go that way. http://www.horsepowerfreaks.com/price/Mazda/Miata/Fidanza/Engine/Cam_Gears

 

[StepInTheMirror]

Is there a good thread on one of the many miata forums that explains the proccess of this exhintake mod?

I did some miata.net searching and found a bunch of nothing.

Sounds like a nice cost effective mod though, especially since I think I've got an exhaust cam laying around somewhere!

Im glad that you're enjoying your mod.

 

[Caldera]

I'll post a how-to tomorrow. Quick and easy. I found the process through a bunch of different threads, none of which mentioned the ever-critical "cut-your-cam" step.

 

[renesisdrms]

nice mod caldera. one question. is the exhaust cam considerably bigger than the intake cam? would you happen to know or measured the lift profiles?

and here is just a thought...don't cars typically have the bigger intake cam (lift and duration) than its exhaust lil brother due to the nature that exhaust valves only pushes the lower volume inert gases out...sorry, i feel like i'm missing something here.