Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Engine Performance (https://www.miataturbo.net/engine-performance-56/)
-   -   Why you dont cheap out on rods on a rebuild. (https://www.miataturbo.net/engine-performance-56/why-you-dont-cheap-out-rods-rebuild-40500/)

y8s 10-24-2009 01:59 PM

Why you dont cheap out on rods on a rebuild.
 
So I was tearing down the spare 2001 motor I have in my shed today... (got it from fmowry who purchased the car from Robbi Laurenson who ran a haltech and water injection and maybe around 250 rwhp if I recall all that correctly) and pulling out the pistons to send across the pond and found this:

http://gallery.y8s.com/d/21910-1/DSC_0704.JPG

http://gallery.y8s.com/d/21914-1/DSC_0705.JPG

http://gallery.y8s.com/d/21917-1/DSC_0706.JPG


Yes that's right folks! FOUR BENT RODS. Not sure if this matters, but 1 and 4 were bent in the plane of the rod and 2 and 3 were bent out of plane.

I think the motor had less than 650,000 miles on it at this point. frank can pipe up on that though. Everything else looks great. No serious wear on any parts or surfaces.

go figure.

go get rods for your build for $300.

hustler 10-24-2009 02:04 PM

bmw:
http://amsteam.net/files/2/ams_20_rods_03.jpg

hustler 10-24-2009 02:04 PM

yeap...aside from the block, our little motors are shit in comparison to just about any other 4-cylinder.

Full_Tilt_Boogie 10-24-2009 04:11 PM


Originally Posted by hustler (Post 472845)
yeap...aside from the block, our little motors are shit in comparison to just about any other 4-cylinder.

I wouldnt say any other 4-cylinder, but most any modern 4-cylinder, yes...

B18C5 FTMFW!

tyson87 10-24-2009 04:17 PM


Originally Posted by Full_Tilt_Boogie (Post 472900)
I wouldnt say any other 4-cylinder, but most any modern 4-cylinder, yes...

B18C5 FTMFW!

my buddy is parting his out right now. u need rods or pistons?

JasonC SBB 10-24-2009 04:24 PM

Would a motor run seemingly normally with rods like that ???

y8s 10-24-2009 05:28 PM

I bet neither owner of the car had any clue that there was something wrong. There's really no way to know that the rods look like that until you tear it down.

a bent rod that's only marginally shorter will hardly show up on a compression test...

kotomile 10-24-2009 05:40 PM

Daaaamn, they did that with 250 hp?

Gulp.

tyson87 10-24-2009 05:43 PM

i dont think its a matter of whp, isn't det. what kills rods?

Toddcod 10-24-2009 05:44 PM


Originally Posted by hustler (Post 472845)
yeap...aside from the block, our little motors are shit in comparison to just about any other 4-cylinder.

I can't agree with that. I think the 1.6L is one of the best motors ever made. And so did few magazines for a while.

I buy nothing but 90-93 to turbo. Bone stock motors, as old as they are. I never work on them. They Run great and hold up well to boost. psi for psi, I would tear up the honda's.

Yea the new motors are startig to carry more power. But will they have the legacy that these have had. I doubt it.

For the dated technology on these motors, they still hold their own. And if clean, N/A and under 190,000 miles are usually still very dependable.

Braineack 10-24-2009 05:44 PM


Originally Posted by tyson87 (Post 472922)
i dont think its a matter of whp, isn't det. what kills rods?

torque pushes down on the pistons, too much and they squish the rods.

y8s 10-24-2009 06:07 PM


Originally Posted by tyson87 (Post 472922)
i dont think its a matter of whp, isn't det. what kills rods?

that's just it, the pistons look pristine

http://gallery.y8s.com/d/21929-1/DSC_0713.JPG

There's no broken lands or pitting or any obvious signs of repeat offending detonation. plus as I mentioned, there was a water injection system hooked up.

I think the rods were just designed for no boost.

tyson87 10-24-2009 06:15 PM

with the rods bent did it F up the cyl walls?

ZX-Tex 10-24-2009 06:16 PM

Bent two (killed one) of the four stock rods in my stock engine last year (as some of you may remember). Everyone was quick to blame detonation, but I do not think that is what did it. I think it was 16 psi with a GT2560 on a cold morning :giggle:

Too much power = too much cylinder pressure = too much compression load on the stock rods = Euler column bucking (a.k.a. bent rods).

225 < Too much power < 300 WHP (based on anecdotal evidence, assuming stock redline).

kotomile 10-24-2009 06:17 PM

Look at the positive side, it was a DIY variable-compression engine!

rrjwilson 10-24-2009 07:45 PM


Originally Posted by kotomile (Post 472942)
Look at the positive side, it was a DIY variable-compression engine!

Differential compression surely :D

NoMiEzMX-5 10-25-2009 12:11 AM

The award for the best 4 banger has to go to the mighty 4G63..hands down..

kotomile 10-25-2009 12:18 AM

Best 4-banger?

http://image.turbomagazine.com/f/854...bochargers.jpg

Billet block, 55 psi, 4,000hp. I win.

Norwood Racing's 4,000 hp Max-4 Integra - Tech Review - Turbo Magazine

magnamx-5 10-25-2009 12:32 AM

yeah this is all the more reason for me to put in my mtuned rods that ive had for th epast 2 yrs almost and nvr installed.

NA6C-Guy 10-25-2009 12:58 AM

More the reason I have completely decided against any boost on my stock rods. My $1000 and 3 month long rebuild was completely useless because I cheaped on the rods. Go me!


All times are GMT -4. The time now is 10:25 PM.


© 2024 MH Sub I, LLC dba Internet Brands