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Old 08-16-2006, 12:34 PM   #1
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Question Question about engine internals

Now that I've pretty much reached the "safe" limits of my stock engine internals (I know that a few people have run a lot more boost on stock internals, but I am not in the mood to buy a new engine anytime soon ), I was wondering how "hard" it is to put in stronger pistons/rods yourself?

I've done all the work on my miata to date including suspension/clutch/turbo (and all assorted parts)/TB/water pump/brakes/diff swap, but I'm a bit wary about cracking the engine open. I'm sure you need some extra tools, but that's always a good excuse to go buy more tools so not a huge issue. Just thinking about a good winter project in advance and I would like to know if it's a reasonable job or something only for the professionals. Thanks.
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Old 08-16-2006, 12:51 PM   #2
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I know I'm not answering your question, but I really would not build an engine without first getting a proper ECU, like a Link, MS, or EMU. You might be able to squeeze a little more power out as well. 15psi on 230cc injectors already sounds crazy enough to me.
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Old 08-16-2006, 12:53 PM   #3
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you need:
engine stand
good torque wrench
expandable pliars / tweezers for rings and clips
assymbly lube


you should also get rings, wrist pins, main bearings, and new ARP connecting hardware for everything. Also, get the cylinder walls hones out since its cheap. This stuff is very easy to assemble. I also recommend freshening up the head. Its pretty easy to do a home-grown port and polish job, and it opens up alot more power accross the full rpm range.
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Old 08-16-2006, 12:57 PM   #4
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Quote:
Originally Posted by Al Hounos
I know I'm not answering your question, but I really would not build an engine without first getting a proper ECU, like a Link, MS, or EMU. You might be able to squeeze a little more power out as well. 15psi on 230cc injectors already sounds crazy enough to me.


Contact kingofl337

He can build you a ms system to plug and play with fuel and spark. Thats really all you need if you get the car professionally tuned, and run enough retard under load. I've seen people add stand alone engine management on vr6 vw engines and pick up 40whp, and make more power all over the rev band.
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Old 08-16-2006, 01:18 PM   #5
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Tom,

I have to agree with the ECU route. For the price of the ECU and tuning, you're going to have a far more reliable and safe configuration. In this regard, I recommend something with knock sensing capabilites that can pull timing instantaneously per incident.
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Old 08-16-2006, 01:43 PM   #6
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No Al, Tom is crazy He does have one fast greddy miata though. He's running an EMU and I was surprised how well it was tuned. I did not hear a audible knock. Then again I only drove it a few miles and at 12psi. I hope I get a ride in his car before he blows his engine. :gay:




Quote:
Originally Posted by Al Hounos
15psi on 230cc injectors already sounds crazy enough to me.
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Old 08-16-2006, 02:15 PM   #7
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back to engines, if you do plan to enforce the engine, i think it's easier to work on another while you continue to drive the car. miata blocks are easy and cheap to get.

i have thought about doing this to a 1.6 block and build up a longblock with 323gtx internals, pull the old engine, swap the head, install new motor. this way, i would know i have a working block (the old one) and it would minimize downtime.

installing pistons rods and such does take the aforementioned tools. a crush gauge, a caliper, and a VERY good engine manual would make it fool-proof.
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Old 08-16-2006, 02:25 PM   #8
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15 psi on 230's even with auto tune i dont see how it makes power hell you would need to run 130+ fp. Oops just saw pieburg on the mods list my bad. i didnt think our injectors liked that much pressure. interesting.
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Old 08-16-2006, 02:50 PM   #9
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Okay I'm a bit crazy, but not totally crazy.

I am running an emanage blue with olderguy's autotune so it is not complete chaos. Originally, I had a set of 310cc injectors that I was going to throw in, but olderguy said he was running his 1.8cc injectors without any problems around 12psi-ish so I figured that I'd give it a try. So some data just to assure you that I am not completely crazy:

Last year on the dyno I was running an AFR of below (yes, that says below) 10 b/c my o2 sensor was shot and the car was running super rich. Since then, I've put in a WB o2 sensor (Innovate LC-1) which has been calibrated. I recently replaced the WB with a new one after a DAC failed in the first controller, but both WBs showed an AFR of around 12 at full boost (from both logged runs and an LED gauge). Both were well grounded and calibrated according to the manual (I even let the car sit for a few days before the free air calibration) so I doubt that both WB readings are incorrect. Also, I'd imagine that the car would run like crap if the WB was totally off as I have the NB simulator feed the ECU off boost.

The emanage is also pulling a relatively safe 1 degree of timing per psi of boost even on cool days with a big IC. I have a step colder plugs and run 93 octane as well. I did try to advance the timing a bit, but started to audibly ping as well as saw the real oil pressure gauge ticking to the right so I backed off to the original setting until I get a chance to hit the dyno and do it right.

I did back off the mbc to about 12-13psi, but the WB is still reporting AFRs of around 12-12.5 when in boost and there is no audible, nor oil pressure gauge ping so I feel that the setup is running with a pretty decent street tune. Assuming that the WB reading is correct, my AFRs seem reasonable in boost and I retarded timing to ~2-4 degrees more than when I heard audible knock or saw the opg ticking to the right. Again, I hope to get the the dyno soon to both verify my data as well as fine tune the fuel curve/timing as needed.

I can see how a complete aftermarket ecu would add the benefits of a knock sensor/retard, temp based adjustments, and a few other safety benefits, it's just not worth the cost right now (as not too many used links are up for sale lately) since it seems to me that the car is reasonably tuned. I am thinking about one of those knock sensor devices that pull timing though.

Only the dyno will tell, but the car feels much, much faster now than it did before when it was making 190rwhp do I figure that I am getting closer to the limits of stock internals and the car will be off the road for almost 3 months in the winter. Would be nice to have the extra safety factor of stronger internals and tempting to put in larger injector and up the boost a bit.
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Old 08-16-2006, 03:17 PM   #10
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Quote:
Originally Posted by magnamx-5
15 psi on 230's even with auto tune i dont see how it makes power hell you would need to run 130+ fp. Oops just saw pieburg on the mods list my bad. i didnt think our injectors liked that much pressure. interesting.
I don't know if this make a difference of not, but my 1.8 injectors are off a 99 miata. They look completely different from the 1.8 injectors off a 94-97.

Supposedly they have a lot more headroom that the older 1.8 injectors according to the gurus at m.net. I posed the question of why they were different on m.net a long time ago and either RodH or markp said that they have more headroom, but no numbers proof. Also, IIRC the 99 miata has a returnless fuel rail that runs at a higher base pressure than our cars so maybe the injectors can also handle higher pressures. I'm not sure, but it's working as far as I can tell and I have close to 2k miles now with this setup.
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Old 08-16-2006, 10:23 PM   #11
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tom you might want to just put in larger injectors and limit your fuel pressure a bit. The worst time to lock an injector would be in heavy boost, like 15psi at 7000rpm in a higher gear. I think that might just do your motor in. Plus i agree with kung fu to build another motor taking your time and accumulating tools, parts, and knowledge.
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