Analyzing a critical engine flaw in the 4b11 by TTP
Evolving Member
Joined: Jun 2007
Posts: 109
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From: New Zealand
With inlines, there's definitely the potential for starving the last cylinder of air due to the intake manifold design, namely the air coming in from one end of the manifold and not 'making it' to the far end. Maybe a combination of exhaust manifold design too.
If you look at the V10 and V12 Porsche and Ferrari engines, the air enters the intake manifolds in the middle. Pretty sure Lamborghini too.
If you look at the V10 and V12 Porsche and Ferrari engines, the air enters the intake manifolds in the middle. Pretty sure Lamborghini too.
Wouldn't that make the last cylinders run rich instead of lean? From my understanding rich runs colder than lean. So those cylinders would suffer from too much air instead of not enough
Normally.... rich does cool things. So in speculating that it could possibly be a lean issue at one cylinder. Is there a way for the stock ECU to provide just one injector with a specific pulse width to tailor it's AFR? I know I have seen race setups ( assume using a standalone ) appear to have EGT sensors on every exhaust port for that purpose.
My simplistic reasoning makes me think that if heat is an issue, then meth injection and upgraded intercoolers would be good too?
Normally.... rich does cool things. So in speculating that it could possibly be a lean issue at one cylinder. Is there a way for the stock ECU to provide just one injector with a specific pulse width to tailor it's AFR? I know I have seen race setups ( assume using a standalone ) appear to have EGT sensors on every exhaust port for that purpose.
Registered User
Joined: Aug 2002
Posts: 128
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From: The big wide world
Hi guys
Are your aware what piston type you are running in the failed motors ?
Have a look @ www.ralliart.com , download the evo x grpn papers .You will see there was a number of early changes to piston type . Page number 74 of 87
Hope this helps
David
Are your aware what piston type you are running in the failed motors ?
Have a look @ www.ralliart.com , download the evo x grpn papers .You will see there was a number of early changes to piston type . Page number 74 of 87
Hope this helps
David
Last edited by evo400; Mar 28, 2010 at 05:13 AM.
Evolving Member
Joined: Jun 2007
Posts: 109
Likes: 0
From: New Zealand
Hi guys
Are your aware what piston type you are running in the failed motors ?
Have a look @ www.ralliart.com , download the evo x grpn papers .You will see there was a number of early changes to piston type . Page number 74 of 87
Hope this helps
David
Are your aware what piston type you are running in the failed motors ?
Have a look @ www.ralliart.com , download the evo x grpn papers .You will see there was a number of early changes to piston type . Page number 74 of 87
Hope this helps
David
Evolving Member
Joined: Jan 2009
Posts: 327
Likes: 0
From: Denver, CO
Lol nothing on the people here, but i found it funny that this thread is right on top of this.
https://www.evolutionm.net/forums/ev...ml#post8131489
https://www.evolutionm.net/forums/ev...ml#post8131489
https://www.evolutionm.net/forums/8141002-post34.html
Newbie
Joined: Sep 2007
Posts: 59
Likes: 0
From: california
I think you jinxed it.... way to go! 2 days later and BOOM...
https://www.evolutionm.net/forums/8141002-post34.html
https://www.evolutionm.net/forums/8141002-post34.html
Evolved Member
Joined: Mar 2008
Posts: 972
Likes: 0
From: Mid-West IL
Hi guys
Are your aware what piston type you are running in the failed motors ?
Have a look @ www.ralliart.com , download the evo x grpn papers .You will see there was a number of early changes to piston type . Page number 74 of 87
Hope this helps
David
Are your aware what piston type you are running in the failed motors ?
Have a look @ www.ralliart.com , download the evo x grpn papers .You will see there was a number of early changes to piston type . Page number 74 of 87
Hope this helps
David
These failures look very similar to the B15 Sentra SR20 failures when adding a turbo. The root cause of those failures was the top ring landing was too high and after too many heat cycles would crack looking just like this.
According to what i have read on the SR20 failures the higher ring landings promote better emissions. I haven't compared the 4g63 pistons to the 4b11, and i could be totally off base, just looking at the failures compared to another similar failure on a different motor platform. I would also be hard pressed to think that a company with 20+ years in turbo experience would get something like ring gaps incorrect.
According to what i have read on the SR20 failures the higher ring landings promote better emissions. I haven't compared the 4g63 pistons to the 4b11, and i could be totally off base, just looking at the failures compared to another similar failure on a different motor platform. I would also be hard pressed to think that a company with 20+ years in turbo experience would get something like ring gaps incorrect.
The EvoX top ring is 5.5 mm down and the 4G63 topring is 5mm down . As for the ring end gap on a 4g63 is usually around .010-.012 from the factory for the top ring. The majority of ring end gaps are from aftermarket piston makers who use forged pistons compared to the factory cast/hyper pistons which do no expand as much. I will say though .007 does seem kind of small.
