Strokered engine block cracked
#1
New Member
Thread Starter
Strokered engine block cracked
The car is equipped with a 4.1L BC stroker, Darton sleeves, 100mm bore pistons, twin turbo kit (GTX28 x2), & a Hollinger sequential gearbox. While the car was being tuned on the dyno, motor oil started leaking from the block, it was obvious that the block had cracked. The tune was almost done, reaching around 750 whp. The block had multiple cracks in the crank case , (check the attached images). During the tune the car was subject to hard/harsh gear shifting as we were setting the ignition cut needed for the flat shifting feature. I wonder if that had caused such block damage or whether the VQ35DE is generally weak for such power level. I also wonder if installing further mods such as aftermarket main caps & girdle could've prevented such issue.
I'm currently searching for a another block, I'd appreciate your feedback how to prevent such issue from happening again.
I'm currently searching for a another block, I'd appreciate your feedback how to prevent such issue from happening again.
#2
General & DIY Moderator
MY350Z.COM
MY350Z.COM
iTrader: (64)
Sorry to hear about this failure, but at least it didn't happen during a race weekend. While I'm no expert, you are obviously exceeding the design specs of the VQ block with this project. Sequential gearboxes only add to this stress.
#4
New Member
iTrader: (23)
Sorry.......
Having an Billet Girdle is a MUST in a build like this.
How was the motor broken-in? Miles before Dyno?
Where did you get the Block?
Did you have it Magnifluxed?
Who installed the sleeves?
Who built the motor?
What were the Clearances?
Having an Billet Girdle is a MUST in a build like this.
How was the motor broken-in? Miles before Dyno?
Where did you get the Block?
Did you have it Magnifluxed?
Who installed the sleeves?
Who built the motor?
What were the Clearances?
Last edited by OldManZ350; 05-27-2017 at 09:55 PM.
#5
New Member
Thread Starter
Thank you for the feedback guys, torque was around 678ft lb
The block was purchased used, it was not magnufluxed, break in period was very short I'm afraid. If you check the photos, the cracks are at the crank compartment, so sleeves & clearances has nothing to do with the issue. I spoke with a VQ35 specialist shop & they told me that such cracking is common at such power level & they offered me a billet block, I'm seriously considering it, it might be a once & for all solution.
The block was purchased used, it was not magnufluxed, break in period was very short I'm afraid. If you check the photos, the cracks are at the crank compartment, so sleeves & clearances has nothing to do with the issue. I spoke with a VQ35 specialist shop & they told me that such cracking is common at such power level & they offered me a billet block, I'm seriously considering it, it might be a once & for all solution.
#6
New Member
iTrader: (18)
I'm not an engine builder expert but most shops are biased to provide an answer that gets you to buy something for them.
I can tell you that most anecdotal reports of block failures are due to no billet girdle and sleeve installation issues.
I have never heard of a block cracking without (improperly installed) sleeves and with billet girdle. 700 ft lbs is no issue for an unsleeved block. If you want to go beyond that then sleeves might be worthwhile but very few have a proven track record (e.g. Dynosty). Even one of the Darton facilities have several failures under their belt.
Good luck
PS. A used, heat cycled block is preferred over a new block btw
I can tell you that most anecdotal reports of block failures are due to no billet girdle and sleeve installation issues.
I have never heard of a block cracking without (improperly installed) sleeves and with billet girdle. 700 ft lbs is no issue for an unsleeved block. If you want to go beyond that then sleeves might be worthwhile but very few have a proven track record (e.g. Dynosty). Even one of the Darton facilities have several failures under their belt.
Good luck
PS. A used, heat cycled block is preferred over a new block btw
Last edited by rcdash; 05-31-2017 at 10:43 PM.
#7
New Member
iTrader: (1)
Was Mazworx the shop that you spoke with? I have been following their new billet block production for the past couple months and have been considering it as well. You can answer me in a pm if you'd rather not say here.
It's always sad to see stories like this though, and I truly wish you all the best moving foward.
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#9
New Member
iTrader: (23)
Absolutly......
I'm not an engine builder expert but most shops are biased to provide an answer that gets you to buy something for them.
I can tell you that most anecdotal reports of block failures are due to no billet girdle and sleeve installation issues.
I have never heard of a block cracking without (improperly installed) sleeves and with billet girdle. 700 ft lbs is no issue for an unsleeved block. If you want to go beyond that then sleeves might be worthwhile but very few have a proven track record (e.g. Dynosty). Even one of the Darton facilities have several failures under their belt.
Good luck
PS. A used, heat cycled block is preferred over a new block btw
I can tell you that most anecdotal reports of block failures are due to no billet girdle and sleeve installation issues.
I have never heard of a block cracking without (improperly installed) sleeves and with billet girdle. 700 ft lbs is no issue for an unsleeved block. If you want to go beyond that then sleeves might be worthwhile but very few have a proven track record (e.g. Dynosty). Even one of the Darton facilities have several failures under their belt.
Good luck
PS. A used, heat cycled block is preferred over a new block btw
#10
New Member
iTrader: (6)
Darton sleeves are probably the culprit here, as mentioned. Improper install is a major issue, as the shop has to remove a lot of structural material from the block to make room for the new sleeves, and if there is any excessive clearance that could allow flex or insufficient clearance that could allow the sleeve to cause pressure points in the surrounding casting when temperatures change, you can end up with a cracked block.
#13
New Member
iTrader: (9)
We did a couple drag cars awhile ago that would crack in almost the same place and it ended up coming from the fact we were still using factory motor mount plates with solid bushings, went to a front and mid plate and removed the factory mounts and never had the same problem again.
You can see the front plate in this picture on my car.
You can see the front plate in this picture on my car.
Last edited by meatbag; 06-08-2017 at 06:05 AM.
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dkmura (06-09-2017)
#17
New Member
Thread Starter
We did a couple drag cars awhile ago that would crack in almost the same place and it ended up coming from the fact we were still using factory motor mount plates with solid bushings, went to a front and mid plate and removed the factory mounts and never had the same problem again.
You can see the front plate in this picture on my car.
You can see the front plate in this picture on my car.
#18
New Member
...
We did a couple drag cars awhile ago that would crack in almost the same place and it ended up coming from the fact we were still using factory motor mount plates with solid bushings, went to a front and mid plate and removed the factory mounts and never had the same problem again.
You can see the front plate in this picture on my car.
You can see the front plate in this picture on my car.
Might not be a bad idea as a preventative measure.
Last edited by rearranged; 06-09-2017 at 01:13 PM.
The following 2 users liked this post by meatbag:
Leforce (06-11-2017),
OldManZ350 (06-11-2017)
#20
New Member
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What he said.......
This Guy has a lot of knowledge and experience with the VQ. Don't be to quick to dismiss he's help as you did mine.
If you know what did not cause the block to crack, then you should be able to figure this out on your own and not need our help.
This Guy has a lot of knowledge and experience with the VQ. Don't be to quick to dismiss he's help as you did mine.
If you know what did not cause the block to crack, then you should be able to figure this out on your own and not need our help.
Last edited by OldManZ350; 06-11-2017 at 03:27 PM.
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Leforce (06-11-2017)