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Old 11-17-2015, 11:20 PM   #1
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Default Which Pistons to use?

The background,
First, I am new and apologize if you all have seen this a thousand times before. I own a 1990 that now has 203,000 miles and consumes a quart of oil about every 800 mi. the plan is a 1.8 swap and then turbo. The goal is roughly 280 wheel hp. I am a college student and have a very tight budget, so I go for the cheaper options when available (megasquirt). I recently got an engine from a '95 with about 60k miles on it and plan on doing some internal upgrades before swapping it in.I would rather have an overbuilt engine than one close to it's limit. I already have a set of aftermarket connecting rods and am looking at other necessary parts. I know the trans is a consumable item at that power level and I will need to upgrade the diff and do a coolant reroute among other things. The 1.8 will go in the car with internal upgrades but not see boost until I can afford a (used) turbo Kit. This car will primarily be a fun weekend/auto-x and a possibility of a track day, and the occasional mountain run.

Onto the questions

1) I have a set of pistons from a '99 and a '95. for a boosted application and my relative lack of knowledge on how to tune a MS2 which compression ratio would be best?

2) Would I be able to get away with the stock oil pump and a better harmonic damper at this power level? It is a lot easier to upgrade the pump now but it is expensive and I would not need it until boosted. the harmonic balancer/damper is much easier to change later.

3) For 280 wheel hp are head studs necessary, valve springs?

I know that I cannot afford a turbo system now and the engine is getting rings/bearings and rods. the crank needs a polish, and the bores honed. I might look into a little careful diy headwork, clean the HLA's and a valve job. I figured this is the best place to ask, and feel free to list any other internal engine pieces that you think might be needed at this power level.
thanks and
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Old 11-18-2015, 12:09 AM   #2
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Those 95 and 99 engine pistons for a 1.8L engine will not fit into the 1.6L engine that you have.
In order to safely make 280 whp without blowing stuff up, you should get Supertech 9:1 compression ratio pistons. Having the piston crowns and the combustion area of the engine thermal coated by a company like Swain Coating will make things safer.
You should also upgrade to a NB engine with the later and more efficient head design which will allow you to achieve your power goals with stress on the engine.
Your plans are NOT going to be cheap or low budget.
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Old 11-18-2015, 12:54 AM   #3
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Quote:
Originally Posted by my97miata View Post
Those 95 and 99 engine pistons for a 1.8L engine will not fit into the 1.6L engine that you have.
The guy just said that he "recently got an engine from a '95". So this is moot.



JustThisGuy, 280 HP is a pretty lofty goal, and if you're committed to using OEM pistons, I'd definately err on the side of caution with the lower compression ratio of that '95.


That said, my97miata does raise one valid point, in that the port of the '99-'05 heads is vastly improved over the '94-'97 heads, and will make achieving large amounts of power easier.


You'll need both valve springs and head studs, however the OEM pieces will be fine. Valve springs are only an issue when you decide to increase the RPMs or run silly camshafts, which is mostly the resort of the naturally-aspirated crowd. (Ok, fine, technically the OEM head fasterers are bolts, not studs. But I'm already being a smartass here, logic isn't necessary.)


That said, speaking from the experience of someone who was a car nut during college, it's not a great time to be spending time and money on cars. They'll still be there after you graduate. I drove a stock '71 VW Beetle and a Honda CB250 in college. Hated both of 'em. But they worked.
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Old 11-18-2015, 01:32 AM   #4
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Quote:
The goal is roughly 280 wheel hp. I am a college student and have a very tight budget,
This will end well.

IMO, even if you were a college graduate with a good job and therefore decent budget, I would tell you to shoot for 220whp with a 6500 redline and call it a day. If you have a tight budget, you need to do things in stages, with affordable safe **** first.

95 engine is fine to start. Replace the clutch with a strong one (ie, ACT HD 6 puck or XTSS). That's 450 of your budget gone. Oh yeah, and you need a 1.8L rear end because the stock 1.6L one is made of glass. There's more money.

The minimum you will need is turbo, manifold, plumbing, intercooler, ecu, injectors, sensors, gauges, etc. There's a few grand more gone.

If you assemble that properly you'll have a stupidly fast car that is a blast to drive and will be nearly oem reliable for years. 12 psi is plenty.

Keep in mind that since you have a legitimately old car, lots of ordinary **** will be naturally falling apart on it and failing. You will need enough budget to stay on top of these things, because cooling problems or a failing fuel pump, etc that aren't a big deal with 90whp are a huge deal when you have 300.

If you go for > 250 whp, your budget is going to get a lot higher because almost everything starts becoming unreliable at that point.
You will basically need to do a complete engine rebuild with new rods, pistons, oil pump, harmonic balancer, etc.

Realistically, your 280whp budget should look like:
labor: you're going to need help prepping the block
rods: 400
pistons: 500
oil pump: 400
harmonic damper: 400
clutch: 450
injectors, ecu, sensors, gauges, lots of small stuff: 2000+
intercooler: $ebay
turbo + mani: at least a grand?
piping: $few hundred?

This is not a cheap hobby and I'm not overly confident you can pull this off with no money.
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Old 11-18-2015, 01:36 AM   #5
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Honestly, if I was in college and had just gotten a miata, I'd put small amounts of money into stuff like clutch, rear end, suspension, brakes, etc while I saved money to do the real mods.

Also, it helps enormously if you have a second car to drive while your miata is being worked on. This will save you tons of money in the long term, since you can do the work yourself without rushing or panicking because you need to drive to work in 8 hours.
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Old 11-18-2015, 01:47 AM   #6
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What he said ! Plus $$ for machining , it's going to cost at least 50% more than you anticipate. My budget for any project is to take what I think it'll cost and double it. I don't start until that money is in the bank. Unless you have access to a shop and tools don't even think about going there.

Quote:
Originally Posted by AlwaysBroken View Post
This will end well.

IMO, even if you were a college graduate with a good job and therefore decent budget, I would tell you to shoot for 220whp with a 6500 redline and call it a day. If you have a tight budget, you need to do things in stages, with affordable safe **** first.

95 engine is fine to start. Replace the clutch with a strong one (ie, ACT HD 6 puck or XTSS). That's 450 of your budget gone. Oh yeah, and you need a 1.8L rear end because the stock 1.6L one is made of glass. There's more money.

The minimum you will need is turbo, manifold, plumbing, intercooler, ecu, injectors, sensors, gauges, etc. There's a few grand more gone.

If you assemble that properly you'll have a stupidly fast car that is a blast to drive and will be nearly oem reliable for years. 12 psi is plenty.

Keep in mind that since you have a legitimately old car, lots of ordinary **** will be naturally falling apart on it and failing. You will need enough budget to stay on top of these things, because cooling problems or a failing fuel pump, etc that aren't a big deal with 90whp are a huge deal when you have 300.

If you go for > 250 whp, your budget is going to get a lot higher because almost everything starts becoming unreliable at that point.
You will basically need to do a complete engine rebuild with new rods, pistons, oil pump, harmonic balancer, etc.

Realistically, your 280whp budget should look like:
labor: you're going to need help prepping the block
rods: 400
pistons: 500
oil pump: 400
harmonic damper: 400
clutch: 450
injectors, ecu, sensors, gauges, lots of small stuff: 2000+
intercooler: $ebay
turbo + mani: at least a grand?
piping: $few hundred?

This is not a cheap hobby and I'm not overly confident you can pull this off with no money.
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Old 11-18-2015, 02:23 AM   #7
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Quote:
Originally Posted by JustThisGuy View Post
The background,
First, I am new and apologize if you all have seen this a thousand times before. I own a 1990 that now has 203,000 miles and consumes a quart of oil about every 800 mi. the plan is a 1.8 swap and then turbo. The goal is roughly 280 wheel hp. I am a college student and have a very tight budget, so I go for the cheaper options when available (megasquirt). I recently got an engine from a '95 with about 60k miles on it and plan on doing some internal upgrades before swapping it in.I would rather have an overbuilt engine than one close to it's limit. I already have a set of aftermarket connecting rods and am looking at other necessary parts. I know the trans is a consumable item at that power level and I will need to upgrade the diff and do a coolant reroute among other things. The 1.8 will go in the car with internal upgrades but not see boost until I can afford a (used) turbo Kit. This car will primarily be a fun weekend/auto-x and a possibility of a track day, and the occasional mountain run.

Onto the questions

1) I have a set of pistons from a '99 and a '95. for a boosted application and my relative lack of knowledge on how to tune a MS2 which compression ratio would be best?

2) Would I be able to get away with the stock oil pump and a better harmonic damper at this power level? It is a lot easier to upgrade the pump now but it is expensive and I would not need it until boosted. the harmonic balancer/damper is much easier to change later.

3) For 280 wheel hp are head studs necessary, valve springs?

I know that I cannot afford a turbo system now and the engine is getting rings/bearings and rods. the crank needs a polish, and the bores honed. I might look into a little careful diy headwork, clean the HLA's and a valve job. I figured this is the best place to ask, and feel free to list any other internal engine pieces that you think might be needed at this power level.
thanks and
Cheapest would be a 1.8 motor, with a set of forged ebay rods, hone and new rings, get head rebuilt (use all stock parts, this will cost about 250-300 dollars). That will get you a fresh motor that will make 280whp, but you'll break a piston if you detonate it much, or try to push over 300+whp (I've broken stock pistons on two motors in a row at 20+ psi). If you learn to tune on it before going turbo, 280whp is very doable with rods-only bottom end. For reference, FM sells turbo kits that will make 250whp (maybe more) with a stock motor.

As mentioned, do a 99 head swap. That will make your goal of 280whp a lot easier.
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Old 11-18-2015, 03:45 AM   #8
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Damn, you guys are a bunch of party poopers.

Guy has a shot 1.6. Has a good NA8 motor. He is going to put stronger rods in it and reassemble.

OP, if you're going to track the car it'd be a good idea to upgrade the pump, but it's not totally necessary. For a happy middle ground you might consider an OEM VVT pump--higher capacity than what you have, but cheaper than a BE pump.

Either set of pistons will work fine, and with a built bottom end will stand up to your goal with careful tuning. I'd go with whichever are in better condition. All things being equal, I'd suggest the lower comp '95 pistons.

You're building one step at a time. I'm guessing by your post that you have a pretty good idea of what you're doing, and the work involved in rebuilding an engine. If you don't, then please read the posts from the party poopers very carefully.

Nothing wrong with doing it on a tight budget. Nothing wrong with using stock pistons for a street car if you've got a good tuner. No need at all to spend the money to do an NB head in order to meet your goals. Would it be better? Sure. But not necessary.
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Old 11-18-2015, 09:00 AM   #9
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Thanks for all the quick replies. just to clear up a few things, this is a long term project and it probably will not see boost for a few years, but I after riding in a miata with a full FM II kit and one with an LS2 I got a pretty good idea of the power I would want.
280 is more of a max power figure, and if it ends up only making 265 that is fine with me. It seems that lower compression is better and the '95 pistons seem to be in better shape anyway. The turbo parts will be collected over the next few years, and I do have access to the school's machine shop. I will consider a '99 head in the future but I can swap it with the engine in the car.
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Old 11-18-2015, 09:18 AM   #10
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$300 rods
$100 rings
$125 bearings
$25 HG
$75 various other bottom end gaskets (only use OEM)
$xxx machine shop costs to re-hone the block.

Those are the minimum costs of doing a rods only bottom end. My real advice is buy a daily driver.
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Old 11-18-2015, 10:25 AM   #11
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Didn't really make it clear, the Miata is a weekend car, I have a Subaru Outback as a Daily, plus I live on campus and only drive on weekends. I also have a set of C.A.T H-beam rods already, so my costs for the engine alone are roughly
rings $100
bearings $125
gaskets $100
machine shop (depends on tools I can use at school) $500 worst case
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Old 11-18-2015, 10:44 AM   #12
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Are we really talking about a bare bones budget build, on a car that will be getting built over several years?

It's gonna take you 3 years to come up with $825?

if you're that poor, don't modify cars. you should be doing better things with your money
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Old 11-18-2015, 12:12 PM   #13
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Shake the sand out of your vaginas and read what the OP is saying.

The TURBO build is going to take time. He is not in a rush to build and wants to take his time. He has a daily. **** guys aside from the fact that he isn't rolling in money this guy is on the right track, and there's nothing wrong with doing a budget build.
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Old 11-18-2015, 12:15 PM   #14
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Plan on a bit more $100 for gaskets. I think all OEM will run you about $75 from Rosenthal for the bottom end and most of the ones for the head.
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Old 11-18-2015, 12:17 PM   #15
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Originally Posted by turbofan View Post
Shake the sand out of your vaginas and read what the OP is saying.

The TURBO build is going to take time. He is not in a rush to build and wants to take his time. He has a daily. **** guys aside from the fact that he isn't rolling in money this guy is on the right track, and there's nothing wrong with doing a budget build.
No time to read, too busy hating. Cry moar
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Old 11-18-2015, 12:52 PM   #16
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Most of us have been as poor as OP at one time or another and lack of funds is just not conducive to serious car modding. Even a bare bones turbo setup on a miata is outside the bounds of ramen noodle budget people- you need a job that covers you financially plus a bunch left over every month to make this work.

I figure he'll be fine if he takes it slow, but he pretty much won't have a 280whp miata until his financial situation significantly improves.
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Old 11-18-2015, 01:13 PM   #17
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For the same money you are about to spend rebuilding your engine, you can put together a barebones turbocharger setup on the stock '95 block that will make ~200whp without much trouble. 280whp is in the no-man's land of Miata powere, where you are only 30-40whp past what the stock internals can handle, but the cost of making 280whp is about 2x the cost of making 200-220whp.

If I were in your shoes, I would re-evaluate your goals.
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Old 11-18-2015, 01:16 PM   #18
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OP will be fine with this attitude. I went through about the same situation while in school, aspiring for turboners. As long as you do it in stages to spread out costs whole following the MT.net formula you will be successful.

1- Diff install and learn MS in current state while toying with your 1.8.
2- Finish 1.8 and install, break in + retune.
3- Buy quality used turbo bits when possible and new where necessary.
3.5 - Omit crucial step of investing in wheels, suspension, and driving skill because broke power hungry college student.
4- Boost parts on car at low psi, retune. (Maybe stop here a la Savington's post until graduation and $$$ are real)
5- Eventually increase boost for 280000whp, retune and win.

Having a second car will make it much more realistic. I did not, but I QC'ed often to make sure that wouldn't be a problem. If you research and plan it is possible assuming your car is not a POS in general. Unexpected costs of such a car would have wrecked me. It will cost you either way, but you can always put it on pause since you have a daily.
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Old 11-18-2015, 04:34 PM   #19
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OP will be fine with this attitude. I went through about the same situation while in school, aspiring for turboners. As long as you do it in stages to spread out costs whole following the MT.net formula you will be successful.

1- Diff install and learn MS in current state while toying with your 1.8.
2- Finish 1.8 and install, break in + retune.
3- Buy quality used turbo bits when possible and new where necessary.
3.5 - Omit crucial step of investing in wheels, suspension, and driving skill because broke power hungry college student.
4- Boost parts on car at low psi, retune. (Maybe stop here a la Savington's post until graduation and $$$ are real)
5- Eventually increase boost for 280000whp, retune and win.

Having a second car will make it much more realistic. I did not, but I QC'ed often to make sure that wouldn't be a problem. If you research and plan it is possible assuming your car is not a POS in general. Unexpected costs of such a car would have wrecked me. It will cost you either way, but you can always put it on pause since you have a daily.
These are the steps I am following with the exception of 3.5 as I have 205/50's on avanti storm 15x8s and enjoy the auto-x. My plans may shift to suspension after the 1.8 is in and running, but the current next step for me is a diff. I don't expect to get to step 4 until after school unless someone gives me free parts (it's happened before). Before I did anything to improve performance I baselined the car and it has a new clutch, brakes, front wheel bearings, convertible top, fluids, clutch master and slave cyl, and has been about 70k mi since the last timing belt. Now I know the direction I am going with the engine better, Ill work on it over winter break, and keep an eye out for a '94-'05 diff
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Old 11-18-2015, 05:52 PM   #20
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Drop the '95 1.8 in and build a car to "handle" your proposed HP.
There is much more than dropping a boosted lump in, like bigger brakes, Torsen, i'd put a newer/better trans, cat back etc…..then a Squirt.
Collect your engine/turbo parts while enjoying your dialed in Miata.
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