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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 11-13-2012, 09:14 PM   #1
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Lightbulb Pistons

I want to start a thread so in the future ppl like me can elect what kind of piston set up is best for there application and budget. I myself am new to the world of miata's (one year deep), and I know somewhere down the road this will help those who don't know how to use the search button.

I've been reading about FM's forged piston setup for the 1.6L and 1.8L engines (I believe they are 9.0:1 CR wiseco w/ Carrillo rods)... but traditionally this may prove expensive to some people. I have also looked into the ebay route... they, on the other hand, promise forged pistons and rods for a much more affordable price; however they only carry 8.5:1 compression ratio wiseco slugs with Manley rods for the 1.6L B6. The folks at FM insist that the 9.0:1 CR is the best midpoint when it comes to compromising low-end with high-end boost for all miata's 89-05.

*Now is the time you guys should jump in with your knowledgeable opinions/ facts, and enlighten me and the public about Compression Rations (and types of pistons/rods) in relation with boost as well as for the normally aspirated if you want.

As for my miata, I am currently negotiating is a small ihi turbo setup controlled by a megasquirt unit that will supply a modest 14 psi to my 91 (short nose) 1.6. Obviously, being that I like my hard earned money, I'm trying to keep the costs as low as possible without compromising quality/ durability. This winter I plan on pulling out the one-six and getting it back on its feet (its full of noises and it leaks like hell).

I have heard about how the stock CR is actually not bad and boost friendly (9.4:1 I think)... so I came up with the idea to use stock pistons and simply reinforce with forged rods. Is this idea poop or might it actually be good? Are there other factors I may be over looking? I don't know, but that is why I need your input/ feed back.

Last edited by Joe Perez; 11-15-2012 at 12:00 AM. Reason: Added line breaks.
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Old 11-13-2012, 09:18 PM   #2
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OH boy, here we go for the 1000000th time

Is it national n00b thread day?

Yes, for the millionth time your stock pistons will be fine. Re-ring them and add forged rods.

And learn to use the paragraphs. That **** is painful to read.
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Old 11-13-2012, 09:45 PM   #3
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lol okay
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Old 11-13-2012, 10:00 PM   #4
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That's very nice of you. But you assume that in the future people will USE the search button. We have no reason to believe this, since nobody ever does.

https://www.miataturbo.net/engine-pe...ns+forged+rods

Though I do admit that the default sorting is terrible, always do 'advanced search' then 'sort by relevancy'. This was #10 on that list.
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Old 11-13-2012, 10:09 PM   #5
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okay bud thanks. that was helpful.
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Old 11-14-2012, 04:33 PM   #6
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9:1 is the wrong choice. You want 8.6:1.
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Old 11-14-2012, 10:57 PM   #7
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Quote:
Originally Posted by Savington View Post
9:1 is the wrong choice. You want 8.6:1.
Thanks Andrew. I'm also trying to make a piston choice. Can you elaborate on the differences further?
The 8.6:1 offers detonation advantages, but the 9:1 is touted for its off boost response.
If the car only sees 3-4 track events a year and the rest of the time its street driven, which way would you lean and why.
Also, another factor that would affect piston choice would be the turbo. Lets say you wanted to just break into the 300 whp zone.
Thanks for your help
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Old 11-15-2012, 02:19 AM   #8
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turbo, exhaust manifold, exhaust, boost control and ignition map all have WAY more effect on "driveability" and "off boost response" than 0.4 compression ratio difference.

it simply doesn't matter as much as all the other parts in a turbo setup.
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Old 11-15-2012, 02:26 AM   #9
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Quote:
Originally Posted by 2manyhobyz View Post
Thanks Andrew. I'm also trying to make a piston choice. Can you elaborate on the differences further?
The 8.6:1 offers detonation advantages, but the 9:1 is touted for its off boost response.
If the car only sees 3-4 track events a year and the rest of the time its street driven, which way would you lean and why.
Also, another factor that would affect piston choice would be the turbo. Lets say you wanted to just break into the 300 whp zone.
Thanks for your help
Simple - BPs make power on timing, not boost. Lower compression allows for more timing at the same boost level, and thus more power throughout the powerband. If you intend on making enough power to require a built motor with a turbo, and you're going to run it on pump gas, you want 8.6:1 pistons.
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Old 11-15-2012, 09:17 AM   #10
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What it comes down to, IMO, is what fuel you intend to use.
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Old 11-15-2012, 10:12 AM   #11
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Would there be an advantage to using something like 10:1 if you were planning to run 110?
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Old 11-15-2012, 10:25 AM   #12
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Roller wave soft head.

lol @ anyone arguing about compression ratio.
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Old 11-15-2012, 10:39 AM   #13
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Quote:
Originally Posted by TheDriver View Post
Would there be an advantage to using something like 10:1 if you were planning to run 110?
Maybe..."yes" if you run corn.
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Old 11-15-2012, 12:08 PM   #14
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Baller turbo pistons:

Roller-Wave forced induction pistons incorporate full stepped-quench pads to maximize (mechanical octane), a volume-biasing reflector trench on the exhaust-side, turbulators at the intersect of the valve relief's to increase mixture homogeneity, and piston skirt designs for minimal cylinder wall loading.

All 280hp ITR pistons:

Road racers around the world run these Roller-Waves with ultra-high 19mm pin placement for use with the longest-possible connecting rods. Combined with 87.2mm stroke (ITR) cranks, these 85.0mm pistons net just below 2.0 liters. We stock both the pistons and the corresponding lightweight Crower rods.
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Old 11-15-2012, 12:19 PM   #15
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I ran 8.5:1 je FSR pistons in my eclipse... very very nice.
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Old 11-15-2012, 12:22 PM   #16
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Quote:
Originally Posted by Jdilla View Post
I ran 8.5:1 je FSR pistons in my eclipse... very very nice.
Did they still have good quench? I know JE and most like to raise the wrist pin to drop compression and that sucks.
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Old 11-15-2012, 12:31 PM   #17
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Quote:
Originally Posted by hustler View Post
Maybe..."yes" if you run corn.
Considering "corn" is typically 100-105 I would think 110 would be fine
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Old 11-15-2012, 12:38 PM   #18
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Quote:
Originally Posted by TheDriver View Post
Considering "corn" is typically 100-105 I would think 110 would be fine
lol wut...

Where did you convert that? I think it can get as high as 115. But there is no true way to rate e85 on octane.
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Old 11-15-2012, 01:00 PM   #19
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Quote:
Originally Posted by Erat View Post
lol wut...

Where did you convert that? I think it can get as high as 115. But there is no true way to rate e85 on octane.
85 octane, bro.
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Old 11-15-2012, 01:36 PM   #20
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Ethanol has a different molecular compund than octane.

So i don't get it.
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