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-   Engine Performance (https://www.miataturbo.net/engine-performance-56/)
-   -   Exintake swap? (https://www.miataturbo.net/engine-performance-56/exintake-swap-26031/)

thesnowboarder 09-15-2008 02:08 AM

Exintake swap?
 
I read about an exintake swap in airbrush1's thread but didn't want to jack his, the mod consists of putting an exhaust cam in place of the intake cam. I did a search both here and on m.net and couldn't find much info.

Anyone wanna chime in? What would be a benefit of doing this? What would be a downfall if any?

KPLAFIN 09-15-2008 02:10 AM

Apparently it gives you a few horses for NA power, not so much for boosted cars. try searching for exhintake (with the "h") and you'll probably get a few more search hits.

MattEGTR 09-15-2008 10:37 AM

"Apparently" being the operative word. Half of the people that try it claim it works, the other half see no benefit, with the only difference being that the powerband has been moved up in the RPM range.

That's the impression that I get from the Protege forums, anyway.

patsmx5 09-15-2008 10:41 AM

The information is out there, but it's scattered and not well organized. In short you have to drill a locating hole in the cam gear so that the new exhaust cam is indexed correctly. 197.5* clockwise of the old hole is the right spot I think (from memory, go look it up).

This mod will increase lift and duration.

Ben 09-15-2008 10:54 AM

If done on turbo car, it probably should be done with adjustable wheels to allow for the increased duration with less overlap. Should be a marked improvement in power if tuned.

airbrush1 09-15-2008 12:29 PM

we need a definitive thread.

patsmx5 09-15-2008 12:45 PM


Originally Posted by airbrush1 (Post 308342)
we need a definitive thread.

Indeed, and it needs to pay strict attention to the separation of solid lifter and hydraulic lifter motors. I'll contribute what I know later from my research. I have an extra 99' exhaust cam I'm gonna put in some time. When I do it I will definitely take lots of pics and do a writeup, as the info on this swap for a 99 is terrible.

KPLAFIN 09-15-2008 12:49 PM


Originally Posted by patsmx5 (Post 308347)
Indeed, and it needs to pay strict attention to the separation of solid lifter and hydraulic lifter motors. I'll contribute what I know later from my research. I have an extra 99' exhaust cam I'm gonna put in some time. When I do it I will definitely take lots of pics and do a writeup, as the info on this swap for a 99 is terrible.

Try to do some before and after dyno pulls too if you haave time/access to a cheap dyno.

patsmx5 09-15-2008 12:53 PM


Originally Posted by KPLAFIN (Post 308350)
Try to do some before and after dyno pulls too if you haave time/access to a cheap dyno.

That would be nice. But it probably won't happen. I'm waiting to put the cam in till I get rid of this miss I have. I need two more Millenia COPs and I will switch to COP in hopes of remedying my ignition miss. Car runs strong right now, but I know having a random miss is holding it back some. Besides I'll probably see higher than typical gains from a cam swap as I have a lot of head work done.

fahrvergnugen 09-15-2008 09:22 PM


Originally Posted by patsmx5 (Post 308347)
Indeed, and it needs to pay strict attention to the separation of solid lifter and hydraulic lifter motors.

Are all NAs mechanical? Also, what is the interval of adjustment on them?


Also, who did your head work? Cost?

MattEGTR 09-15-2008 09:26 PM

NAs have hydraulic lifters.

fahrvergnugen 09-15-2008 09:29 PM

They went mechanical on later cars? Really?

MattEGTR 09-15-2008 09:34 PM


Originally Posted by fahrvergnugen (Post 308535)
They went mechanical on later cars? Really?

Yarly.

patsmx5 09-15-2008 10:00 PM


Originally Posted by fahrvergnugen (Post 308529)
Are all NAs mechanical? Also, what is the interval of adjustment on them?


Also, who did your head work? Cost?

89-93's have 1.6L and hydraulic lifters. Can't do the exintake swap on these though as the CAS sensor is driven off the intake cam. Bolt an exhaust cam in its place and there will be no provision to drive said sensor.

94-97's have the CAS driven off the exhaust side. Just cut the drive off an exhaust cam and install it in place of the old intake cams. Hydraulic lifters on this motor too.

99+ has solid lifters, and more aggressive cams.

I did my own head work.

EDIT: headwork cost me probably 200 tops. Would cost anybody I did it for 1K+

fahrvergnugen 09-15-2008 11:20 PM


Originally Posted by patsmx5 (Post 308547)
99+ has solid lifters, and more aggressive cams.


I guess they went 'backwards' to wring every little bit of power they could out of that motor... I've been around VWs too long...



Originally Posted by patsmx5 (Post 308547)
EDIT: headwork cost me probably 200 tops. Would cost anybody I did it for 1K+


Not to come off as critical, but did you have access to a flow bench? Or have you had prior experience with P&Ps?

patsmx5 09-15-2008 11:27 PM


Originally Posted by fahrvergnugen (Post 308584)
I guess they went 'backwards' to wring every little bit of power they could out of that motor... I've been around VWs too long...





Not to come off as critical, but did you have access to a flow bench? Or have you had prior experience with P&Ps?

I don't understand what you mean by the first part.

No I didn't flow bench the head, nor did I "port and polish it". If you're curious as to what I did PM me.

iWeasel410 09-15-2008 11:51 PM

http://members.aol.com/solomiata/cams.html

Scroll down, looks like same lift longer duration.

patsmx5 09-16-2008 12:00 AM


Originally Posted by iWeasel410 (Post 308594)
http://members.aol.com/solomiata/cams.html

Scroll down, looks like same lift longer duration.

94-97 that is true. 99-00 the exhaust cam has more lift and duration.

iWeasel410 09-20-2008 06:11 PM

http://www.diymiata.com/exhintake.html

Shainz 09-29-2008 08:18 AM

We need more definite answers! I'm looking forward to doing this mod.


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