The reason the VQ35 breaks with FI
12-07-2006, 10:34 AM
#23
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Thx for the responses guys....
I guess it really is hit or miss with a stock block and FI even with a good tune,
It seems to me that the guys running pistons and rods in built blocks arent having blwon motors like the stock block guys, which suggests that the rods and pistons are the weak point, that said, people have beat on their stock block for years and had no problems.
I wonder if some motors are just stronger than others from the factory?
I guess it really is hit or miss with a stock block and FI even with a good tune,
It seems to me that the guys running pistons and rods in built blocks arent having blwon motors like the stock block guys, which suggests that the rods and pistons are the weak point, that said, people have beat on their stock block for years and had no problems.
I wonder if some motors are just stronger than others from the factory?
12-07-2006, 07:08 PM
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IMO sleeving this block is just a waste of money for most of the people here (excluding the handful of guys). All that needs to be upgraded for big numbers is Rods Pistons and address the headlift issues and your set. Hell before i got my Z i had a non intercooled SC'd 3.0L maxima making near 320whp on stock timming. This was with running 12psi of boost. Now i no these are not big numbers, but the conditions which that motor was subjected to was pretty sad (ie. high heat, poor tune of A/F and timming). The motor ran great until it ran into oil starvation issues. This just goes to show that the VQ motor can take abuse.
The VQ in stock form is a very strong motor if tuned correctly. You have to remember that when you slap FI on a NA designed motor with aggressive timming you are asking for trouble.
The VQ in stock form is a very strong motor if tuned correctly. You have to remember that when you slap FI on a NA designed motor with aggressive timming you are asking for trouble.
12-07-2006, 08:39 PM
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Originally Posted by chris'smax
IMO sleeving this block is just a waste of money for most of the people here (excluding the handful of guys). All that needs to be upgraded for big numbers is Rods Pistons and address the headlift issues and your set. Hell before i got my Z i had a non intercooled SC'd 3.0L maxima making near 320whp on stock timming. This was with running 12psi of boost. Now i no these are not big numbers, but the conditions which that motor was subjected to was pretty sad (ie. high heat, poor tune of A/F and timming). The motor ran great until it ran into oil starvation issues. This just goes to show that the VQ motor can take abuse.
The VQ in stock form is a very strong motor if tuned correctly. You have to remember that when you slap FI on a NA designed motor with aggressive timming you are asking for trouble.
The VQ in stock form is a very strong motor if tuned correctly. You have to remember that when you slap FI on a NA designed motor with aggressive timming you are asking for trouble.
I remember the PFI dyno was 420whp....HAL? 500whp....compare that to 140whp or whatevr stock... VQ30 > VQ35
12-07-2006, 09:30 PM
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Originally Posted by 300zxSteve
If im not mistaken the vq30 and vq35 are completly different, imo the vq30 handled boost WAY better for being a smaller less powerful motor to begin with. Ive seen hundred of retarded maxima owners that know nothing about boost, showing off their vortech dynos with 13:1 AFR's, helll even 14:1 at redline. I actually posted this a long time ago here, and I asked how the hell the vq30 could stand such abuse,,(no intercooler, bad tuning, 11+psi, extremly lean fuel, etc..)
I remember the PFI dyno was 420whp....HAL? 500whp....compare that to 140whp or whatevr stock... VQ30 > VQ35
I remember the PFI dyno was 420whp....HAL? 500whp....compare that to 140whp or whatevr stock... VQ30 > VQ35
True the Vq35 has a longer stroke, higher compression, and a few other differences, but the basic design to my knowledge is still the same. I truly believe the reason you see so many max's survive this stuff is because the stock ecu has a conservative timming curve. The 350z ecu is to my knowledge substantialy more aggressive than the max, which leads to alot of peoples problems.
I am pretty sure that the rods diameters are still the same between the two and are constructed of the same materials. I'll check to make sure though.
12-08-2006, 02:36 AM
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Where i am now we have 7 FI including my self and 1 mechanic shope and 1 Guy that we can Trust, the 1st 4 blew engines and the same reason was on all connecting rods bent. I think the z pistons r fine on 6 or 7 psi but the rods r very week and now these 4 r rebuilt and another three joind them same shop same guy for tuning and all of us r boosting happily with no problems.
12-08-2006, 03:02 AM
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Originally Posted by silver nismo
Where i am now we have 7 FI including my self and 1 mechanic shope and 1 Guy that we can Trust, the 1st 4 blew engines and the same reason was on all connecting rods bent. I think the z pistons r fine on 6 or 7 psi but the rods r very week and now these 4 r rebuilt and another three joind them same shop same guy for tuning and all of us r boosting happily with no problems.
12-08-2006, 03:13 AM
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Originally Posted by taurran
Saying those blown motors were simply due to weak connecting rods is an oversimplification of the issue. They bent/broke most likely due to abuse, detonation, and/or improper tuning.
12-08-2006, 11:44 AM
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I really believe a lot of the motors are built unequally. Some blow due to rods failing and some because rods bolts let go. The newer 05-06 Rev-up motors seem to hold higher boost much better then the 03-05.
They're have been a handful that run 400whp on the stock block without blowing and some have when they were tuned by the same tuner. I really believe the motors that stay together are made on Mondays
The rest were made Tues-Friday.
They're have been a handful that run 400whp on the stock block without blowing and some have when they were tuned by the same tuner. I really believe the motors that stay together are made on Mondays
The rest were made Tues-Friday.
12-08-2006, 12:25 PM
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Originally Posted by Q45tech
Why would any engineer chance the accountants wrath by over designing any NA engine to tolerate over pressure from boost for long - a pure waste of money proving the engineer is unfit to keep his job.
The cheapest parts that will do the job [make it thru warranty and 100k which ever is sooner] is what mass production is all about.
Computers have enabled maunfacturers to wring out all the waste of yore, where you overbuilt, as the easiest method of creating longevity.......this wasteful concept was dropped im the mid 90's designs which went into production in 2002.
Look back at the J30/300zx engine [castiron block] even in it's mild boosted form almost every internal component was different and strengthened.
Hopefully the engineers use every stock internal failure on the web as proof they did their job well and frugally! See boss another one bit the dust see how good I am...........not a gram of extra weight in any of MY DESIGNS.
The cheapest parts that will do the job [make it thru warranty and 100k which ever is sooner] is what mass production is all about.
Computers have enabled maunfacturers to wring out all the waste of yore, where you overbuilt, as the easiest method of creating longevity.......this wasteful concept was dropped im the mid 90's designs which went into production in 2002.
Look back at the J30/300zx engine [castiron block] even in it's mild boosted form almost every internal component was different and strengthened.
Hopefully the engineers use every stock internal failure on the web as proof they did their job well and frugally! See boss another one bit the dust see how good I am...........not a gram of extra weight in any of MY DESIGNS.
Damn, you're good!
12-08-2006, 12:41 PM
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Originally Posted by EM-EFER
I really believe a lot of the motors are built unequally. Some blow due to rods failing and some because rods bolts let go. The newer 05-06 Rev-up motors seem to hold higher boost much better then the 03-05.
They're have been a handful that run 400whp on the stock block without blowing and some have when they were tuned by the same tuner. I really believe the motors that stay together are made on Mondays The rest were made Tues-Friday.
They're have been a handful that run 400whp on the stock block without blowing and some have when they were tuned by the same tuner. I really believe the motors that stay together are made on Mondays
The rest were made Tues-Friday.Sharif tuned my car at 11.5 psi stock block last weekend. I had nothing better else to do today, so I went to the local Dyno Jet. This it wat it put down today. I hope I can tap into the 11's this weekend on street tires.
12-08-2006, 12:59 PM
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Originally Posted by eagletanggreen
This is true my rev-up was built on Monday
Sharif tuned my car at 11.5 psi stock block last weekend. I had nothing better else to do today, so I went to the local Dyno Jet. This it wat it put down today. I hope I can tap into the 11's this weekend on street tires.
Sharif tuned my car at 11.5 psi stock block last weekend. I had nothing better else to do today, so I went to the local Dyno Jet. This it wat it put down today. I hope I can tap into the 11's this weekend on street tires.
12-08-2006, 01:03 PM
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Originally Posted by chris'smax
True the Vq35 has a longer stroke, higher compression, and a few other differences, but the basic design to my knowledge is still the same. I truly believe the reason you see so many max's survive this stuff is because the stock ecu has a conservative timming curve. The 350z ecu is to my knowledge substantialy more aggressive than the max, which leads to alot of peoples problems.
I am pretty sure that the rods diameters are still the same between the two and are constructed of the same materials. I'll check to make sure though.
I am pretty sure that the rods diameters are still the same between the two and are constructed of the same materials. I'll check to make sure though.
The guys at Arias and Probe said my oem rods should be able to handle 500hp max
All I know is, im going to put arp rod bolts on my 287 when I go FI
12-08-2006, 02:19 PM
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Originally Posted by 300zxSteve
Let me know if they are the same/similar rods...
The guys at Arias and Probe said my oem rods should be able to handle 500hp max
All I know is, im going to put arp rod bolts on my 287 when I go FI
The guys at Arias and Probe said my oem rods should be able to handle 500hp max
All I know is, im going to put arp rod bolts on my 287 when I go FI
The VQ35 rods are different, and ever so slightly lighter than the VQ30 rods. The also have a larger diameter big end. Both the VQ30 and VQ35 rods are forged pieces.
The guys at Arias and Probe just pulled that 500hp number out of their butts. They really have no information to base that claim on and they just threw a conservative number out there for you.
Why would you pull your motor apart to put ARP rod bolts in and not just replace the rods/pistons???? If I'm going that far I'm going to make sure I don't have to do it again.
