Notices
Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by: KPower

Why you dont cheap out on rods on a rebuild.

Thread Tools
 
Search this Thread
 
Old Oct 25, 2009 | 01:01 AM
  #21  
RotorNutFD3S's Avatar
Elite Member
iTrader: (33)
 
Joined: Jan 2007
Posts: 2,522
Total Cats: 36
From: Newnan, GA
Default

Threads like this are convincing me that overall stress killed my stock rod as well. No one could figure out a definite cause and just trying to start the car one day caused it to bend enough to contact the cylinder wall. It bent on both planes.

Name:  DSC01787.jpg
Views: 199
Size:  69.9 KB
Name:  DSC01790.jpg
Views: 206
Size:  64.2 KB
Old Oct 25, 2009 | 01:33 AM
  #22  
18psi's Avatar
VladiTuned
iTrader: (76)
 
Joined: Apr 2008
Posts: 35,821
Total Cats: 3,482
Default

What confuses the hell out of me is that there are all these people with bent rods, and yet there are 10 times more people running the same kind of power/boost on stock rods for 10's of thousands of miles with no problems.
Did mazda pick-n-choose which cars got shitty rods and which ones got good ones or what? LOL
Old Oct 25, 2009 | 01:39 AM
  #23  
NA6C-Guy's Avatar
Elite Member
iTrader: (1)
 
Joined: Feb 2008
Posts: 7,930
Total Cats: 44
From: Birmingham Alabama
Default

This reminds me of something I read somewhere about R package and SE vehicles got the engines that Mazda deemed the best. I guess the ones that made the most power or were balanced the closest. Is this true? Forget where I saw this.
Old Oct 25, 2009 | 01:46 AM
  #24  
18psi's Avatar
VladiTuned
iTrader: (76)
 
Joined: Apr 2008
Posts: 35,821
Total Cats: 3,482
Default

I do not believe that. But if someone shows any proof I'll be happy to retract my statement.
Old Oct 25, 2009 | 01:52 AM
  #25  
buffon01's Avatar
Elite Member
iTrader: (9)
 
Joined: Sep 2008
Posts: 5,609
Total Cats: 13
From: Michigan
Default

I thought our motors were pretty bad ***, and that the 4g63 was ****. I guess Im wrong
Old Oct 25, 2009 | 01:58 AM
  #26  
NA6C-Guy's Avatar
Elite Member
iTrader: (1)
 
Joined: Feb 2008
Posts: 7,930
Total Cats: 44
From: Birmingham Alabama
Default

Originally Posted by 18psi
I do not believe that. But if someone shows any proof I'll be happy to retract my statement.
I don't believe it either, but I just recall reading it and this topic made it come to the front of my mind. Thought maybe someone else would have some proof for or against this.
Old Oct 25, 2009 | 02:53 AM
  #27  
Joe Perez's Avatar
Boost Pope
iTrader: (8)
 
Joined: Sep 2005
Posts: 34,402
Total Cats: 7,523
From: Chicago. (The less-murder part.)
Default

Originally Posted by NA6C-Guy
This reminds me of something I read somewhere about R package and SE vehicles got the engines that Mazda deemed the best. I guess the ones that made the most power or were balanced the closest.
In order for that to be the case, Mazda would have to run every single engine on a dyno. Lamborghini can afford this luxury. Pretty sure that the first time a BP / B6 gets fired up is after it's had a car installed on it.

Last edited by Joe Perez; Oct 25, 2009 at 08:15 PM. Reason: B6, not B8... Thinking Honda today...
Old Oct 25, 2009 | 03:00 AM
  #28  
pdexta's Avatar
Elite Member
iTrader: (17)
 
Joined: Aug 2007
Posts: 2,954
Total Cats: 184
From: Knoxville, TN
Default

You guys are going to get everyone all paranoid. After 10 months of my noob *** trying to figure out how to tune my rods looked perfect. Turn up the boost!
Old Oct 25, 2009 | 03:09 AM
  #29  
NA6C-Guy's Avatar
Elite Member
iTrader: (1)
 
Joined: Feb 2008
Posts: 7,930
Total Cats: 44
From: Birmingham Alabama
Default

Originally Posted by Joe Perez
In order for that to be the case, Mazda would have to run every single engine on a dyno. Lamborghini can afford this luxury. Pretty sure that the first time a BP / B8 gets fired up is after it's had a car installed on it.
Thats kind of what I figured. I wish I could remember where it was I read it. Seems like it was someone quite reputable. Guess they shouldn't be so reputable in that case.
Old Oct 25, 2009 | 03:53 AM
  #30  
Fireindc's Avatar
Elite Member
iTrader: (13)
 
Joined: Dec 2006
Posts: 7,704
Total Cats: 904
From: Taos, New mexico
Default

**** it, our motors are cheap. More boost ftw.
Old Oct 25, 2009 | 09:25 AM
  #31  
ZX-Tex's Avatar
Elite Member
iTrader: (15)
 
Joined: Dec 2007
Posts: 4,847
Total Cats: 27
From: San Antonio, Texas
Default



Nice article, very interesting read. Thanks for the link.
Old Oct 25, 2009 | 10:05 AM
  #32  
y8s's Avatar
y8s
Thread Starter
DEI liberal femininity
iTrader: (8)
 
Joined: Jun 2005
Posts: 19,338
Total Cats: 574
From: Fake Virginia
Default

Originally Posted by 18psi
What confuses the hell out of me is that there are all these people with bent rods, and yet there are 10 times more people running the same kind of power/boost on stock rods for 10's of thousands of miles with no problems.
Did mazda pick-n-choose which cars got shitty rods and which ones got good ones or what? LOL
this car had no problems either! as i said above, you dont know until teardown if there's an issue.

and part of the "pick n choose" is the higher compression cars.

What bugs me now is that I'm probably driving my own car around with rods that look like that. eek.
Old Oct 25, 2009 | 10:15 AM
  #33  
18psi's Avatar
VladiTuned
iTrader: (76)
 
Joined: Apr 2008
Posts: 35,821
Total Cats: 3,482
Default

As long as they don't bend too much or break I guess the car would be acting normal though, right?

I've been arguing with my dad about this whole "bent rods" issue. He REFUSES TO BELIEVE that you could bend a rod and the engine would still be driving and not knocking or blowing up. This is really helping my argument.
Old Oct 25, 2009 | 10:23 AM
  #34  
gospeed81's Avatar
Elite Member
iTrader: (51)
 
Joined: Nov 2008
Posts: 7,257
Total Cats: 26
From: Spring, TX
Default

For all four to bend like that and not break you'd have to be right at the threshold of what those rods can take...AND not see any detonation. Since detonation usual finds the weak link (weakest rod of set) and causes catastrophic failure, and det is often more prevalent in one cylinder more than others.

It appears that the motor saw just a little too much power, the rods bent and work hardened...becoming "stronger" (although more brittle) and the motor was happy...if not running as designed for a while. Kind of a steady state failure that allowed the motor to keep running.

If anything this points strongly towards EXCELLENT engine management and det prevention...and suggests a real upper limit on torque capacity for stock rods.

y8s: Did either of previous owners ever dyno it? Any idea on peak torque?
Old Oct 25, 2009 | 10:24 AM
  #35  
hustler's Avatar
Tour de Franzia
iTrader: (6)
 
Joined: Jun 2006
Posts: 29,085
Total Cats: 375
From: Republic of Dallas
Default

Originally Posted by ZX-Tex


Nice article, very interesting read. Thanks for the link.
When I was a teenagers and in the first year of college I worked in a VW shop in a warehouse next to Norwood's place. The **** that rolls out of his shop is on another level. We always saw **** in there like Bugattis, Ferraris, Callaways, you name...wild ****.
Old Oct 25, 2009 | 11:13 AM
  #36  
miataspeed2005's Avatar
Senior Member
iTrader: (3)
 
Joined: Jul 2005
Posts: 1,404
Total Cats: 0
From: Connect-I-Cut
Default

But if you notice all the people with stock motors and lots of boost are the 1.6 evey time you hear of someone bending a rod it's in a 1.8 or at least the majority
Old Oct 25, 2009 | 11:41 AM
  #37  
y8s's Avatar
y8s
Thread Starter
DEI liberal femininity
iTrader: (8)
 
Joined: Jun 2005
Posts: 19,338
Total Cats: 574
From: Fake Virginia
Default

Originally Posted by Robbi Laurenson @ m.net
I must be around 225 rwhp at 9 psi, and probably 240+ at 10 psi. That's on an FMII BBB, turbo midpipe and single exhaust with the MoTeC M4 running full sequential, tuned on a WB02 to 0.85 lambda. Timing is FM map from Ken for an '01.

This is probably a low estimate since others are making better power with the same gear. I am adjusting for no dyno tuning.

So far no knock registered on the J&S with water injection. Still going after 12k boosted.
He mentioned planning to go to the dyno in various threads but never posted up results
Old Oct 25, 2009 | 01:13 PM
  #38  
JasonC SBB's Avatar
Elite Member
 
Joined: Jul 2005
Posts: 6,420
Total Cats: 84
Default

Originally Posted by y8s
What bugs me now is that I'm probably driving my own car around with rods that look like that. eek.
Well then now you have the reduced compression ratio you've always wanted!
Old Oct 25, 2009 | 01:33 PM
  #39  
1slowna's Avatar
Junior Member
iTrader: (1)
 
Joined: Oct 2008
Posts: 328
Total Cats: 4
From: Palm Harbor FL
Default

yea this seems kinda crazy. m-tuned guy road around on 360whp for like 8 months no issues and this one bends up rods at 250? looks like im not putting a stock motor back in my car.
Old Oct 25, 2009 | 01:38 PM
  #40  
hustler's Avatar
Tour de Franzia
iTrader: (6)
 
Joined: Jun 2006
Posts: 29,085
Total Cats: 375
From: Republic of Dallas
Default

Originally Posted by 1slowna
yea this seems kinda crazy. m-tuned guy road around on 360whp for like 8 months no issues and this one bends up rods at 250? looks like im not putting a stock motor back in my car.
if you believe these lies, then sure. lol



All times are GMT -4. The time now is 11:06 PM.