paul

iTrader: (21)

what do you think a worked head worth telling your friends about is gonna run?

MikeRiv87

iTrader: (12)

$699.99

TurboTim

iTrader: (9)

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).

Zabac

iTrader: (39)

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.

Ben

iTrader: (33)

No. Don't perpetuate these rumors and lies.

hrk

iTrader: (6)

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

Zabac

iTrader: (39)

No need to get all defensive, didn't mean to get you spammed

AbeFM

iTrader: (3)

No to jump on the bandwaggon, but what's there to do for an NB? Are the MSM cams any better? Is there anything cheap to do in that dept? I already have slightly oversized valves, a bunch of various grinding on things. No adjustable gears or non-stock cams, though.

Zabac

iTrader: (39)

A lot of stuff.

Nothing really.

dvcn

iTrader: (7)

Having run the exhintake cam NA and boosted - I have a lot of doubts about what actually gives the 8-10whp. 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.

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.

MikeRiv87

iTrader: (12)

Exactly Why not?

iWeasel410

1.8L = no flapper

dvcn

iTrader: (7)

The first person to run the exhintake was a Protege guy, 1.8 w/AFM. A couple other followed. IIRC, others were 1.8 into 1.6 chassis swaps.

The MAF on the later cars doesn't make tuning better.

My point is that most of the NA power gain by the cam swap is probably from the afr correction.

paul

iTrader: (21)

Would have been helpful to see dyno curves before and after exintake mod.

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.

elesjuan

iTrader: (11)

Kinda sounds like it might just be a waste of time for a properly tuned car. You'd think with that significant difference in duration it'd actually do more..

elesjuan

iTrader: (11)

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.

dvcn

iTrader: (7)

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!

Ben

iTrader: (33)

There's plenty of posts re: cam timing results on teh dyno. Do a search of m.net in the power mods section.

dvcn

iTrader: (7)

Before doing the exhintake cam and trying to figure out what to degree it to I spent an embarrasing amount of time reading useless threads. Only one guy did a lot of playing with special grind cams and had little gain but he didn't publish good details, making me think that it wasn't tuned properly.

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!

Ben

iTrader: (33)

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.