Kinda bummed out... No Exintake Mod?
#23
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20hp...isn't that about 2psi extra boost? Not worth $700 IMHO.
I have always wanted to do the exhintake mod (have an extra cam from paul) but I think it gives you more overlap not less (assuming you just redrill the OEM gear where "they" tell you to), and I think that's not good for a turbo car.
If I were real cool I'd put both intake and exhaust cams on our camdoctor and get real numbers. If I were even more cool I'd get Tom's (brgracer) FM head and flow test it along with a 99 head (already flowed) and a stock 94 head (at the head shop still to be flowed).
I have always wanted to do the exhintake mod (have an extra cam from paul) but I think it gives you more overlap not less (assuming you just redrill the OEM gear where "they" tell you to), and I think that's not good for a turbo car.
If I were real cool I'd put both intake and exhaust cams on our camdoctor and get real numbers. If I were even more cool I'd get Tom's (brgracer) FM head and flow test it along with a 99 head (already flowed) and a stock 94 head (at the head shop still to be flowed).
#24
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You can buy a 99/00 head for sub $500 and port polish it yourself with $40 worth of bits.
Now quit bitching and do something productive, ask Ben if he has 99 head still for sale..
on subject, seems the exintake will give gains, how much? Dyno and find out.
Stock intake cam: 233° .318"/8.08mm
Stock exhaust cam: 254° .339"/8.61mm
233° is not enough duration regardless if you are NA or FI, you will benefit from more duration (254°) either way.
Same goes for the lift, even though I don't see .53mm more lift doing much without FI though.
Now quit bitching and do something productive, ask Ben if he has 99 head still for sale..
on subject, seems the exintake will give gains, how much? Dyno and find out.
Stock intake cam: 233° .318"/8.08mm
Stock exhaust cam: 254° .339"/8.61mm
233° is not enough duration regardless if you are NA or FI, you will benefit from more duration (254°) either way.
Same goes for the lift, even though I don't see .53mm more lift doing much without FI though.
Last edited by Zabac; 07-02-2008 at 12:55 PM.
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Word
https://www.miataturbo.net/forum/showthread.php?t=18325
Completely stock motor with 90,000 miles
Add turbo and exhintake cam with adjustable gears.
Cam change can be done easily in one evening and costs less than $100, why not do it?
hrk
https://www.miataturbo.net/forum/showthread.php?t=18325
Completely stock motor with 90,000 miles
Add turbo and exhintake cam with adjustable gears.
Cam change can be done easily in one evening and costs less than $100, why not do it?
hrk
#28
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Word
https://www.miataturbo.net/forum/showthread.php?t=18325
Completely stock motor with 90,000 miles
Add turbo and exhintake cam with adjustable gears.
Cam change can be done easily in one evening and costs less than $100, why not do it?
hrk
https://www.miataturbo.net/forum/showthread.php?t=18325
Completely stock motor with 90,000 miles
Add turbo and exhintake cam with adjustable gears.
Cam change can be done easily in one evening and costs less than $100, why not do it?
hrk
#30
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The AFM is way lean down low and too rich up top. My feeling is that the exhintake cam helps to bring the high rpm afr's into only a slighly rich range instead of the stock ridiculously rich setting.
On my 96 1.8, with wideband, with standalone ecu, it was tuned pretty well on WOT. After exhintake installation it required retuning. Every small cam timing change required pretty significant retuning.
My butt dyno can definitely detect 8-10whp and the exhintake did not give that much when comparing apples to apples (tuned before and after vs never tuned).
If you are doing it on the cheap, then drill the hole in the stock gear. If you want to do it right, get adjustable cam gears. I'm pretty sure that drilling per the instructions on m.net adds more than stock overlap. This may or may not be bad for turbo depending on what you setup is.
Adjusting the cam timing did shift the powerband a bit. When tuning for top end it just lost way too much on the low/mid that I set it for low/mid power. Figured that would work better for the turbo install.
It's because of hrk's results that I did the exhintake. It seemed that he got more power out of less boost than most.
I still need to play with cam timing someday. The little bit that I did before was marred by tuning/laptop issues (when adjusting the exhaust cam I was putting in a global ignition offset, so I thought, then the serial port died on the laptop). I need to install the EGT to adjust overlap, I think.
Bottom line: It doesn't do miracles on a tuned NA motor, it might help on an untuned NA and it might do some good on a boosted motor but no one knows just how much.
#32
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I don't think any of the exhintake pioneers had a standalone ecu. Heck, they didn't even have a wideband. They were all running flapper AFM's. Turning the clockspring on an AFM and adjusting the bypass screw does NOT constitute tuning an AFM. You can shift the fuel curve up and down but you can't change the span or the shape of the curve. (seriously, don't get me started on AFM's)
The AFM is way lean down low and too rich up top. My feeling is that the exhintake cam helps to bring the high rpm afr's into only a slighly rich range instead of the stock ridiculously rich setting.
The AFM is way lean down low and too rich up top. My feeling is that the exhintake cam helps to bring the high rpm afr's into only a slighly rich range instead of the stock ridiculously rich setting.
#34
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Word
https://www.miataturbo.net/forum/showthread.php?t=18325
Completely stock motor with 90,000 miles
Add turbo and exhintake cam with adjustable gears.
Cam change can be done easily in one evening and costs less than $100, why not do it?
hrk
https://www.miataturbo.net/forum/showthread.php?t=18325
Completely stock motor with 90,000 miles
Add turbo and exhintake cam with adjustable gears.
Cam change can be done easily in one evening and costs less than $100, why not do it?
hrk
Has anyone EVER done that on a Miata motor with a turbo? That's what we want to see.
those are nice numbers though for that turbo on that motor.
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Edit:
Been doing some looking around and I'm curious..
What about swapping in two exhaust cams from a 99-00 BP? From what I can find they're a little more aggressive than the BP HLA camshafts are. Far as I can tell the Miata and Protege HLAs are identical on exhaust, but intake the miata cams are slightly more duration..
Corksport sells some 205 duration .352 lift cams IIRC are turbo friendly grinds... Stock is 190 intake and 202 exhaust with .338 lift. Theres not much improvement there for $600... dammit.
Been doing some looking around and I'm curious..
What about swapping in two exhaust cams from a 99-00 BP? From what I can find they're a little more aggressive than the BP HLA camshafts are. Far as I can tell the Miata and Protege HLAs are identical on exhaust, but intake the miata cams are slightly more duration..
Corksport sells some 205 duration .352 lift cams IIRC are turbo friendly grinds... Stock is 190 intake and 202 exhaust with .338 lift. Theres not much improvement there for $600... dammit.
#37
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I'm not trying to discourage anyone from doing the install. My experience is just one poorly executed datapoint.
I'm suggesting that if you are turbo, install the cam and adjustable gears. Take the time to properly retune every time a change is made.
I will make a sizable donation to anyone who will provide printouts with dyno, afr's, boost, IAT's, cam timing, ignition timing, fuel, EGT's..... and I'll stop there. This must be done in 2° increments to determine best split and advance/retard at various boost levels(10, 15, 20psi) on a 240whp-350whp otherwise stock 1.8.
I'm serious!
I'm suggesting that if you are turbo, install the cam and adjustable gears. Take the time to properly retune every time a change is made.
I will make a sizable donation to anyone who will provide printouts with dyno, afr's, boost, IAT's, cam timing, ignition timing, fuel, EGT's..... and I'll stop there. This must be done in 2° increments to determine best split and advance/retard at various boost levels(10, 15, 20psi) on a 240whp-350whp otherwise stock 1.8.
I'm serious!
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I will make a sizable donation to anyone who will provide printouts with dyno, afr's, boost, IAT's, cam timing, ignition timing, fuel, EGT's..... and I'll stop there. This must be done in 2° increments to determine best split and advance/retard at various boost levels(10, 15, 20psi) on a 240whp-350whp otherwise stock 1.8.
I'm serious!
I'm serious!
#39
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There are a million threads on how to cut the cam and how and where to drill the indexing hole on a stock gear.
The info on m.net doesn't apply to turbo applications. Well, I haven't done a search on cams there for almost two years so maybe there is new info there. I come here for info now!
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sorry, you're right, I don't recall any exhaust swap & turbo specific threads. most of those cheap bastards are n/a and just drilled and set the exh cam in. but there are plenty of threads regarding adj cam gears and turbo regarding improvements seen on the dyno.