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-   -   So how long will my stock NC motor last (https://www.miataturbo.net/general-miata-chat-9/so-how-long-will-my-stock-nc-motor-last-42053/)

mann 12-14-2009 09:02 AM

So how long will my stock NC motor last
 
Maybe we should do an official pool to see :2cents:

as some of you saw in the dyno day thread it put out 283 whp on my "conservative" tune with peak timing of like 13 degrees at 7k.

Since then I dropped it down two more degrees and added a bit more fuel without any noticeable loss in power (11-11.5 AFR), and put in two baffles in the muffler to slow down the boost creep (jumped to 14 psi at 20 degrees last week!).

Currently running 8psi to 4k, 10 psi 4-7k rpm. Peak torque is ~230 or so vs 140 stock.

For those who don't know the 06-08 NC motor has 10.8:1 compression, all cast internals. Motor was overrevved at least twice at the track with a 4 to 2 money shift last year prior to boost. (hit the same damn bump at the etown straight right at the 3-4 shift point!) Compression numbers were 210 dead even on all 4 just prior to turbo.

It's my second car so I only drive it to beat the crap out of it...in other words, if it was human it would be tiger woods. It has a few auto-x events on it, some 'local' drifting, and will see a track day or two again next year, some official drift events, and maybe hill climbs. About 41k on the car, 4k with boost.

At this point I'm torn--do I build the motor before it blows or let it die a natural death? I know honda guys run their hi comp cast motors to 10+ psi with few issues when actually tuned, with the duratec focus/mz3 crowd usually blowing trannys first, but they supposedly only go to 260 hp or so.
I'm thinking to just ride it till it blows since they are so damn common and cheap. Then I can just pick up a low mileage block and get forged internals and not have to worry about boring and honing. Poll only goes to 20k because that would take two years for me to do if not more and by then I'll definitely be building it.

This is the car...

Braineack 12-14-2009 09:10 AM

Brian's has seen lots of track duty and it running over 300rwhp right?

Doppelgänger 12-14-2009 09:11 AM

2.3 block swap?

Saml01 12-14-2009 09:15 AM

Great editing. Awesome numbers.

mann 12-14-2009 09:25 AM

Brian's has seen track duty from what he says but I'm not sure how much total driving he's done with it since its trailered and certainly not cali-legal. His dyno showed 260 or so IRC...

2.3 swap--it would be easy as they bolt right up. It's a more common block too as ford used it in every 4 cylinder from 2005 up. 2.5 from the current gen of duratecs might work also but I'm not sure.

saml01--thanks still learning premiere its a bear I need a 1080p cam instead of my canon point and shoot :loser:

Doppelgänger 12-14-2009 09:27 AM

Is the constructions of the 2.3 internals any different than the 2.0L ?

mann 12-14-2009 09:36 AM

the turbo disi 2.3 has forged rods and pistons but those mazdaspeed motors are not holding up too great far above 300whp from what I hear.

the na 2.3 has cast junk. If I had to do it now I'd get a forged crank from mazda motorsports, and run wisecos with eagle rods.

airbrush1 12-14-2009 09:41 AM

I say pick up a spare motor and start your build now... that way if and when your stock motor dies a horrible death, you have less downtime.

Doppelgänger 12-14-2009 09:42 AM

I suspect the MS cars aren't running good tunes because the ECUs are teh suckage.

Is the 2.3disi short block the same as the normal 2.3?

mann 12-14-2009 09:49 AM


Originally Posted by airbrush1 (Post 495230)
I say pick up a spare motor and start your build now... that way if and when your stock motor dies a horrible death, you have less downtime.

I know, I should...just being lazy

Originally Posted by Doppelgänger
I suspect the MS cars aren't running good tunes because the ECUs are teh suckage.

Is the 2.3disi short block the same as the normal 2.3?

short blocks are the same...just balance shafts crank rods pistons and heads that are different.

I don't know what goes on with their tunes but on the NC I can dial in whatever timing I need and fuel so I'm not too concerned there. I suppose with bigger than 550's and more than 15 psi there might be issues since the resolution is only like 13 rows and load based vs. map but so far its fine no knock.

m2cupcar 12-14-2009 12:17 PM


Originally Posted by mann (Post 495212)
I'm thinking to just ride it till it blows...

second car = just do it
Just keep an eye out for a stellar deal on a build engine while driving on this one. IMO less boost is less fun.

p51hellfire 12-14-2009 12:28 PM

look at the IM mani at 2:23 I think I saw a jump of electricity lol or something ....

gospeed81 12-14-2009 12:51 PM

That is one NICE torque curve....flat as a table.

mann 12-14-2009 07:59 PM


Originally Posted by p51hellfire (Post 495306)
look at the IM mani at 2:23 I think I saw a jump of electricity lol or something ....

that's the exhaust manifold (opposite on NC)

No idea how or why but that's a fireball from between the turbo and manifold. Really odd as I was taping that I thought "shit was that a flash in the corner of my eye" and then I saw it on the video.

It's weird because the turbo is on there tight, I used an SS gasket and if you put your hand there you don't feel any exhaust leak. There was also no knock or anything weird on the logs for that run either. No soot on the block or that general area. Maybe just from running rich while spooling up until all the air gets flowing at full boost?

mann 12-14-2009 08:00 PM


Originally Posted by gospeed81 (Post 495312)
That is one NICE torque curve....flat as a table.

yeah I keep thinking of that picture in someone's signature about cake and eating it too :fawk:

miataspeed2005 12-14-2009 08:05 PM

IMO it will throw a rod tomorrow.







JP

neogenesis2004 12-14-2009 08:06 PM


yeah I keep thinking of that picture in someone's signature about cake and eating it too
That would be y8s, mayor of noobville.

Savington 12-14-2009 08:19 PM


Originally Posted by mann (Post 495212)
Then I can just pick up a low mileage block and get forged internals and not have to worry about boring and honing.

This is terrible, terrible, awful logic. Built motors are bored to match the set of pistons you supply the machinist, and then they are honed to match the rings. (something about the material or design, not exactly sure what, but my machine shop wanted a set of rings both times.) Do not think for a single second that you can buy forged internals and shove them in a low-mileage block without machine work.

Build your motor now, because when it throws a rod through the side of the case and bends a few valves, you'll have to shell out for a new shortblock.

MartinezA92 12-14-2009 08:27 PM


Originally Posted by Savington (Post 495495)
then they are honed to match the rings. (something about the material or design, not exactly sure what, but my machine shop wanted a set of rings both times.)

This.
The walls have to be honed with a certain grit stone according to what type of rings you have. IMO, if whoever is honing your block doesn't ask for your rings or at least what material they're made out of, you need a new machinist.

harleybutter 12-14-2009 08:57 PM

While it still runs, and I hope it does for some time, take your time to find a high mileage 2.0L or 2.3L and rebuild. It is cheaper when you are not in a rush to build it.


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