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Old 09-18-2008, 03:32 PM   #1
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Default Forged piston choices for a daily driven BP (1.8) swapped 90

Sorry guys, I've done research for my 1.6 and pretty much was settled on what I wanted, but then I came across a decent deal on my 94 parts car really just for the motor and brakes...so I want to continue my 'mild build' on this motor and swap it in.

Since I already have the forged rods from the group buy Ben put on a while ago and should have the billet oil pump gears from the group buy sometime before I die...

I'm really just looking to do piston, rods, oil pump gears, full seals etc, and put the motor in the car and swap in a 99 head at a later date.

There are a TON more options in parts for the 1.8 and than the 1.6...I would like to be able to make 300 all said on done safely...but I'd prolly just be tossing the greddy kit I have laying around from my 1.6 motor to the 1.8 when I swapped it so it wont see that much power immediately...but it seems like it will do OK for a while.

9.0:1 seems to be the preferred CR...but what brands are suggested? And where can I get a decent piston/ring set from (vendor wise)?

PISTONS:
FM Wiseco $563 9.0:1 1mm overbore (= "???)
Normal Wiseco: $500-525ish? 8.6:1 .020" .040" .060" over (Not sure on best price vendor...seems high)
JE $550??-ish w/ rings and wrist pins 9.0:1 .020" .040" .060" over (same here...expensive as nuts...)
Supertech from belfab: $450 w/ rings... 8.6:1 not sure of sizing...**** still confuses me.
What else, where can I find them? What do you suggest


Also, on the 1.8 how far of an overbore is considered safe? (haven't searched sorry!) I know the motor has more room, but there are a ton of options. I'm trying to get out cheap as possible but reliability/saftey is KEY. I'll pretty much have to have everything sent out...I've never done any motor work, nor do I know if I would trust myself to do so.



(the good news is I can finally boost my 1.6 up as soon as I can have time to install everything in my buddies garage once his rock crawler is out! Hooray for not being hustler...)

Last edited by miatamania; 09-18-2008 at 03:43 PM.
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Old 09-18-2008, 10:52 PM   #2
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Should I just ask where the cheapest place to get pistons is? The Noobs get more help/****/trash talking than my overly confusing threads.


lol.

Last edited by miatamania; 09-18-2008 at 11:04 PM.
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Old 09-18-2008, 11:01 PM   #3
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Give Top Speed a call. Theyre right here in NC and can get Wisecos and a few others I believe. 252-321-6356.

Theyre having a dyno day/open house Oct 11th, for any of you miata owners close by. Ill be there, but my miata is still in the garage and not currently running.
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Old 09-19-2008, 12:01 AM   #4
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Most important thing is cold start with forged pistons. I'll be using FM Weiscos (so long as I can get them in a 9.5:1 configuration).
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Old 09-19-2008, 12:10 AM   #5
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Outside of miatas, I've heard several things about different forged pistons. In general, people say the Wiseco's take forever to break in, and if you don't break them in you can crack them. But, if you break them in right, then they're indestructable.

On the other hand, JE's break in quick and work great, but they aren't as strong as the Wisecos, though still really strong.

But that's just what I've heard from different racers over the years. If I buy pistons, I'll buy Wiseco.

And sav, why 9.5? Isn't 9:1 plenty? If I buy pistons, they will be 8:1, not 9:1, and damn sure not 9.5:1.
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Old 09-19-2008, 12:46 AM   #6
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And sav, why 9.5? Isn't 9:1 plenty? If I buy pistons, they will be 8:1, not 9:1, and damn sure not 9.5:1.
Response. I'm going to stick with either this turbo, or a 2560 if I get a good deal on one. After driving a 500whp C5Z, I have no aspirations for 300whp anymore. I'm going to build my motor to be a responsive bulletproof 240-250whp machine and pick up a Vette in 2 or 3 years. You can easily do 240-250whp on 9.5:1, and the higher compression will give me more response and more torque off boost.
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Old 09-19-2008, 01:20 AM   #7
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Outside of miatas, I've heard several things about different forged pistons. In general, people say the Wiseco's take forever to break in, and if you don't break them in you can crack them. But, if you break them in right, then they're indestructable.

On the other hand, JE's break in quick and work great, but they aren't as strong as the Wisecos, though still really strong.

But that's just what I've heard from different racers over the years. If I buy pistons, I'll buy Wiseco.

And sav, why 9.5? Isn't 9:1 plenty? If I buy pistons, they will be 8:1, not 9:1, and damn sure not 9.5:1.

why would you ever go lower than the stock CR unless youre running like 35 PSI??

Have you researched static and dynamic CRs?

9:1 is plenty low for any boost youre ever going to realistically run on a miata on the street. 8:1 is going to lower the crank HP of the engine, lower the EGTs and lower the EGVs. Overall is going to be much less efficient. Ideally you would want to RAISE your CR, problem is, not many people know jack #### about tuning and cant tune an 10 or 11:1 turbo car. The key is tuning, tuning, tuning. You dont need to lower your CR, you DO need to run a stand alone ECU and get the car properly tuned.

I guarantee half the turbo miatas out there arent making the power they should because their engine management is all out of wack.
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Old 09-19-2008, 01:25 AM   #8
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Most important thing is cold start with forged pistons. I'll be using FM Weiscos (so long as I can get them in a 9.5:1 configuration).
I would also very much like to see some 9.5:1 or 10:1 pistons as well...have been considering getting some made by wiseco, sort of like a group buy. If they can make an 11:1 they damn sure can make a 9.5:1 right?
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Old 09-19-2008, 09:26 AM   #9
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why would you ever go lower than the stock CR unless youre running like 35 PSI??

Have you researched static and dynamic CRs?

9:1 is plenty low for any boost youre ever going to realistically run on a miata on the street. 8:1 is going to lower the crank HP of the engine, lower the EGTs and lower the EGVs. Overall is going to be much less efficient. Ideally you would want to RAISE your CR, problem is, not many people know jack #### about tuning and cant tune an 10 or 11:1 turbo car. The key is tuning, tuning, tuning. You dont need to lower your CR, you DO need to run a stand alone ECU and get the car properly tuned.

I guarantee half the turbo miatas out there arent making the power they should because their engine management is all out of wack.
I took statics last semester and I'm in dynamics right now. Though those are different definitions of static and dynamic than you are refering to.

I said I want lower compression because I will be running a lot of boost. Not 35, but probably 20 with a GT3271, and all that on a stock motor. In part, I would lower compression for the safety threshold, although I would take a hit in efficiency for it. But for what I loose in efficiency that hurts power I'll add back with more boost, which is less likely to cause detonation and break my stock motor.

Anyway, I have 9.5:1 stock compression pistons. Buy me some forged 8:1 and I'll trade ya.
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Old 09-19-2008, 09:54 AM   #10
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lol no thanks, the stock pistons would last about 20 mins in my motor.

Just remember that if your planning on being at such high power numbers, youre going to want to pick up a new harmonic balancer or youre going to shatter your oil pump gear and the whole motor goes kaboom.
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Old 09-19-2008, 02:58 PM   #11
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I took statics last semester and I'm in dynamics right now. Though those are different definitions of static and dynamic than you are refering to.

I said I want lower compression because I will be running a lot of boost. Not 35, but probably 20 with a GT3271, and all that on a stock motor. In part, I would lower compression for the safety threshold, although I would take a hit in efficiency for it. But for what I loose in efficiency that hurts power I'll add back with more boost, which is less likely to cause detonation and break my stock motor.

Anyway, I have 9.5:1 stock compression pistons. Buy me some forged 8:1 and I'll trade ya.
BS pat 12-1 is the way to go overbore bout 100 or so then crank it up.
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Old 09-19-2008, 04:45 PM   #12
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lol no thanks, the stock pistons would last about 20 mins in my motor.

Just remember that if your planning on being at such high power numbers, youre going to want to pick up a new harmonic balancer or youre going to shatter your oil pump gear and the whole motor goes kaboom.
*gasp* I know. Rather, I know what I'm doing. I'll keep the stock oil pump. But I will limit RPMs to reduce crank flex that causes the gears to shatter in the first place. (I believe it's crank flex that causes the sintered steel gears to crack, not harmonics) Something between 6500-7000 will be the rev limiter.

Way I see it is the engine as a system is a two stage compressor. First stage is the turbo. I can utilize a heat exchanger after the turbo to remove heat from the charge. After that it goes into the engine and is further compressed before combustion takes place. I can't cool the charge between when the engine compresses it and combustion starts. (assuming no WI or any other fluid that will change phases to remove heat) I will choose lower static compression and offset it with higher boost. Not the most efficient setup, but it's safer. More air, more fuel, less heat. Less chance for detonation. Lower EGT's. Not ideal for spool, not ideal for making HP/PSI, but it's more reliable.
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Old 09-19-2008, 04:58 PM   #13
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Awesome debate. But the original question was where can I find these bitches at for the cheapest price and what size/compression ratio/rings are best suited from a reliable motor. Argue.
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Old 09-19-2008, 05:04 PM   #14
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Originally Posted by miatamania View Post
Sorry guys, I've done research for my 1.6 and pretty much was settled on what I wanted, but then I came across a decent deal on my 94 parts car really just for the motor and brakes...so I want to continue my 'mild build' on this motor and swap it in.

Since I already have the forged rods from the group buy Ben put on a while ago and should have the billet oil pump gears from the group buy sometime before I die...

I'm really just looking to do piston, rods, oil pump gears, full seals etc, and put the motor in the car and swap in a 99 head at a later date.

There are a TON more options in parts for the 1.8 and than the 1.6...I would like to be able to make 300 all said on done safely...but I'd prolly just be tossing the greddy kit I have laying around from my 1.6 motor to the 1.8 when I swapped it so it wont see that much power immediately...but it seems like it will do OK for a while.

9.0:1 seems to be the preferred CR...but what brands are suggested? And where can I get a decent piston/ring set from (vendor wise)?

PISTONS:
FM Wiseco $563 9.0:1 1mm overbore (= "???)
Normal Wiseco: $500-525ish? 8.6:1 .020" .040" .060" over (Not sure on best price vendor...seems high)
JE $550??-ish w/ rings and wrist pins 9.0:1 .020" .040" .060" over (same here...expensive as nuts...)
Supertech from belfab: $450 w/ rings... 8.6:1 not sure of sizing...**** still confuses me.
What else, where can I find them? What do you suggest


Also, on the 1.8 how far of an overbore is considered safe? (haven't searched sorry!) I know the motor has more room, but there are a ton of options. I'm trying to get out cheap as possible but reliability/saftey is KEY. I'll pretty much have to have everything sent out...I've never done any motor work, nor do I know if I would trust myself to do so.



(the good news is I can finally boost my 1.6 up as soon as I can have time to install everything in my buddies garage once his rock crawler is out! Hooray for not being hustler...)
Well to answer the OP, it depends which brand you want. I have no idea who's the cheapest though. Have to do your own research their. But I say buy Wisecos. Not from FM, as they are the most expensive, but rather from whoeverthehellelse has them. I also say, rather than trying to save $15.46 on a set by buying them through ChinaDircteTacoTacoTurboNotHitBLockJDM.com, buy them from someone who has a good reputation. That would mean searching threads most likely for people's build threads to see what they bought, where they got it, and how much they paid.

Now if you will excuse us, back to the thread drift...
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Old 09-19-2008, 05:17 PM   #15
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Or you can look into keeping the OEM pistons and having them tri-coated for heat and oil shedding. Most agree that's good enough to protect against anything your engine will ever see unless you're trying to build a monster.
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Old 09-19-2008, 05:24 PM   #16
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Or you can look into keeping the OEM pistons and having them tri-coated for heat and oil shedding. Most agree that's good enough to protect against anything your engine will ever see unless you're trying to build a monster.
What would coating them do? Will that make the ring landings stronger or less likely to fail? I guess I'm not most as I don't agree that's good enough.
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Old 09-19-2008, 06:31 PM   #17
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Well to answer the OP, it depends which brand you want. I have no idea who's the cheapest though. Have to do your own research their. But I say buy Wisecos. Not from FM, as they are the most expensive
OP, pats and I argued about this like a month ago. Quick search should turn it up. I say get the FM Weiscos because they are different enough to make them better (unless Weisco made the FM design changes in their standard Miata piston). Lots of folks with FM Weiscos in built motors, nobody complains about cold knock or oil consumption.
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Old 09-19-2008, 06:38 PM   #18
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OP, pats and I argued about this like a month ago. Quick search should turn it up. I say get the FM Weiscos because they are different enough to make them better (unless Weisco made the FM design changes in their standard Miata piston). Lots of folks with FM Weiscos in built motors, nobody complains about cold knock or oil consumption.
True. Someone who is considering Wiseco's should call them and find out if they are all the same, or if in fact FM's are still "better". If I were buying pistons I'd call JE and Wiseco and see what both have to say about their products and their competitors products.
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Old 09-19-2008, 07:00 PM   #19
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What would coating them do? Will that make the ring landings stronger or less likely to fail? I guess I'm not most as I don't agree that's good enough.
Actually, the ceramic coating does make the ringlands less likely to fail as it directs heat back up where it belongs and away from the sides of the pistons.
BUT WAIT, there's more!!! If you actually tune or have your car tuned right, you won't be detonating to cause ringland failure. Guess you forgot about that, and the fact that Miata piston failure is extremely rare.
Or like you said, you're not in the most group.
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Old 09-19-2008, 07:17 PM   #20
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Actually, the ceramic coating does make the ringlands less likely to fail as it directs heat back up where it belongs and away from the sides of the pistons.
So where exactly do they ceramic coat the piston such that this will cause heat to be transfered from the ring landing area elsewhere? Keep in mind heat is transfered from high to low.

Quote:
BUT WAIT, there's more!!! If you actually tune or have your car tuned right, you won't be detonating to cause ringland failure. Guess you forgot about that, and the fact that Miata piston failure is extremely rare.
Or like you said, you're not in the most group.
This I agree with, and no I didn't "forget" about it. Read my above post. Pistons, head gaskets, rods, etc etc break from detonation, not power. And most will tell you they had a poor tune which lead to detonation which caused XXX to break. Therefore power didn't break the part. Put stronger parts under detonation and they too will fail. Stronger parts doesn't fix everything. You gotta have the tune and setup to keep detonation from happening. Stronger parts just gives you a bit more wiggle room sorta, but it's not a bullet proof vest against detonation.
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