Our theory on stock rod failure...
06-01-2006, 01:47 PM
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Originally Posted by Oleg
Thank you. I will sign up for the supra forums and see what's up...
I should have done this back in '03.
For all that good looks of the Z and the power potential of the VQ35DE (once buckefulls of $$ are applied), it is still an underengineered POS as opposed to the 2JZ.
I should have done this back in '03.
For all that good looks of the Z and the power potential of the VQ35DE (once buckefulls of $$ are applied), it is still an underengineered POS as opposed to the 2JZ.
06-01-2006, 03:01 PM
#124
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Originally Posted by Weqster
Hey guys. I recently purcahses a 350z. I Have been apart of the forced induction Honda community for over 5yrs now. THis means i am quite accustomed to open decks and the associated downfalls.
There ar a few terms being thrown around here which are cuasing confusing.
Headlift: headlift is a common term used to desicribe combustion gases escaping into the water jackets during boost. People think boost pushes its way outside the cylinder. Sure this happens, but is is mearly an after-effect of another problem
90% of all headlift is the cylinders themselves SHIFTING or SINKING. Due to the open nature of the decks having less support around the cylinder walls, R/S ratio and revolutions causeing extreme sidewall loading of pistons - cylinders actually move around. The slightest movement will brech a headgasket.
So what can i do?
Tuning:
Reduce cylinder pressures. You must run optimal timing. This is not best timing for power, but best timing to minimise cylinder pressures during combustion. The key is timing. A motor can have an a-grade tune and still push coolant.
Mechanical:
Unlike popular beleif, ARP headstuds are not the be all and end all of preventitive mechanics. They will help to a certain point. I have personally pushed coolant 'headlifted' with ARP headstuds. Its in the tune.
Run ductile iron sleeves. This is the ONLY reliable way to save urself from cylinder movement. SIMPLE. In the honda community, stock sleeves only go so far. Get a set of aftermarket sleeves installed by a EXPERIENCED install. I must stress this - only use the best. It is very common to have sleeves sink if not done properly.
If u do decide to run stock sleeves on a built motor - look into o-ringing of the head of block. o-rings are compressable peices of metal installed around the top of the sleeve to help give it that extra tight seal. These do put extra stress on headgaskets, but they are work the risk IMO. They helped me solve my problems.
What shouldnt i do:
I havnt seen these used yet on the VQ motors, but a popular band-aid fox for cylinder movement is a 'block guard'. This is a alluminium support which os installed around the cylinders to give them more support. These CAN help, but mor then likely dont do anything at all. They can however cause overheating problems.
Other spin-off's are the block-gaurd is block filling and block posting. Google for more information on these. Some people swear by them, but the consensis is, these are all bandaid fix's to the real problem.
Once again, i must stress. The tune - correct timing maps - are vital to keeping ur cylinders from dancing around.
Re the original poster;
My opinion on these engine failures is fairly simple. I beleive everyone here, using large single turbos and twin turbo setups, are running the motors on the edge. Reliable and best whp are very different. I beleive these rods failed due to being over-stressed. The original poster commented that one motor blew at 4500rpm. This means it will of been developing a chunkload of torque (peak?) and putting alot of stress on the rods. Torque and/or RPMs kill rods.
To all the other posters thinking about pulling out of F/I after hearing these horror stories. I have no doubt the VQ would be a super reliable motor at 300-350whp. Why be greedy and go for 400whp which is on the edge of safety, and is the point were factory variation component reliability is put to the test.
There ar a few terms being thrown around here which are cuasing confusing.
Headlift: headlift is a common term used to desicribe combustion gases escaping into the water jackets during boost. People think boost pushes its way outside the cylinder. Sure this happens, but is is mearly an after-effect of another problem
90% of all headlift is the cylinders themselves SHIFTING or SINKING. Due to the open nature of the decks having less support around the cylinder walls, R/S ratio and revolutions causeing extreme sidewall loading of pistons - cylinders actually move around. The slightest movement will brech a headgasket.
So what can i do?
Tuning:
Reduce cylinder pressures. You must run optimal timing. This is not best timing for power, but best timing to minimise cylinder pressures during combustion. The key is timing. A motor can have an a-grade tune and still push coolant.
Mechanical:
Unlike popular beleif, ARP headstuds are not the be all and end all of preventitive mechanics. They will help to a certain point. I have personally pushed coolant 'headlifted' with ARP headstuds. Its in the tune.
Run ductile iron sleeves. This is the ONLY reliable way to save urself from cylinder movement. SIMPLE. In the honda community, stock sleeves only go so far. Get a set of aftermarket sleeves installed by a EXPERIENCED install. I must stress this - only use the best. It is very common to have sleeves sink if not done properly.
If u do decide to run stock sleeves on a built motor - look into o-ringing of the head of block. o-rings are compressable peices of metal installed around the top of the sleeve to help give it that extra tight seal. These do put extra stress on headgaskets, but they are work the risk IMO. They helped me solve my problems.
What shouldnt i do:
I havnt seen these used yet on the VQ motors, but a popular band-aid fox for cylinder movement is a 'block guard'. This is a alluminium support which os installed around the cylinders to give them more support. These CAN help, but mor then likely dont do anything at all. They can however cause overheating problems.
Other spin-off's are the block-gaurd is block filling and block posting. Google for more information on these. Some people swear by them, but the consensis is, these are all bandaid fix's to the real problem.
Once again, i must stress. The tune - correct timing maps - are vital to keeping ur cylinders from dancing around.
Re the original poster;
My opinion on these engine failures is fairly simple. I beleive everyone here, using large single turbos and twin turbo setups, are running the motors on the edge. Reliable and best whp are very different. I beleive these rods failed due to being over-stressed. The original poster commented that one motor blew at 4500rpm. This means it will of been developing a chunkload of torque (peak?) and putting alot of stress on the rods. Torque and/or RPMs kill rods.
To all the other posters thinking about pulling out of F/I after hearing these horror stories. I have no doubt the VQ would be a super reliable motor at 300-350whp. Why be greedy and go for 400whp which is on the edge of safety, and is the point were factory variation component reliability is put to the test.
Some of what you were saying here was what I was trying to say in this post. Again I'm still learning and processing all this info...
Originally Posted by atlsupdawg#2
I honestly believe that because the block is not solid it is the culprit here. Under a heavy (FI) load that thing probably "torques" all over the place and what you all are seeing is the end of a "domino effect". Sort like looking at a glacier, in that 90% percent of it's mass is hidden yet all you see is that little 10% bit that's visible. Are the guys with sleeved blocks having the same issues?? Would it be feasible to concentrate on strengthening the block more ie. with a heavier girdle??
I'm still learning so don't blast me too hard..
I'm still learning so don't blast me too hard..
06-01-2006, 03:13 PM
#125
yes guys with sleeves are having problems too. this is why i have been saying it is the head mostly creating the problem. this is also why i had such good luck with my head mod kit when i installed it. now the depth of the sleeves can help if they are sticking up higher than the rest of the block deck and act like an o-ring. this would put more pressure on the head to keep from flexing.
if you think about the direction of the combustion forces in the cylinder, the cylinder sees horizontal expansion, and the head and piston see vertical expansion. if the combustion chamber and piston head shape is correct, (and flat tops or dish styles are best with a center spark plug, all of which the VQ35 has) the horizontal forces should be equal on the cylinder walls.hence the areas that do not have a head stud holding the heads tight are the areas leaking. it is a process of elimination and taking a look at where the forces are applied to create this condition.
if you think about the direction of the combustion forces in the cylinder, the cylinder sees horizontal expansion, and the head and piston see vertical expansion. if the combustion chamber and piston head shape is correct, (and flat tops or dish styles are best with a center spark plug, all of which the VQ35 has) the horizontal forces should be equal on the cylinder walls.hence the areas that do not have a head stud holding the heads tight are the areas leaking. it is a process of elimination and taking a look at where the forces are applied to create this condition.
06-01-2006, 03:15 PM
#126
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Originally Posted by taurran
Bye and good luck with that (signing up on the forums). Enjoy your $30k used car with 125k miles. Oh, and you think modding a supra is cheap? Think again, buddy.
Actually, I got the sticker shock from the price of the used Supras about an hour ago. Way too much, that I'll give you. But here is what my research has revealed:
Used FD RX7 with high mileage and/or blown motor: 4000-5000$
LS1 engine/tranny combo: 6000-7000$
http://www.hinsonsupercars.com/FDTurnkey.htm :8700$
Having an awesome handling car that can run low 12's easy N/A (no chance of blowing the motor)-priceless.
Maybe a 350z with a TN ST is not a pinnocle of more then a century of automotive engineneering after all.
BTW, before you start flaming me for this, make sure that you read up on this conversion further.
P.S. I am still glad that I learned all the stuff about modifying cars on these forums. But as soon as the lease on my daily driver is over, I am trading my Z in for an FJ Cruiser (new DD) and next spring I am starting the FD LS1 project.
06-01-2006, 03:18 PM
#127
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Originally Posted by Oleg
Actually, I got the sticker shock from the price of the used Supras about an hour ago. Way too much, that I'll give you. But here is what my research has revealed:
Used FD RX7 with high mileage and/or blown motor: 4000-5000$
LS1 engine/tranny combo: 6000-7000$
http://www.hinsonsupercars.com/FDTurnkey.htm :8700$
Having an awesome handling car that can run low 12's easy N/A (no chance of blowing the motor)-priceless.
Maybe a 350z with a TN ST is not a pinnocle of more then a century of automotive engineneering after all.
BTW, before you start flaming me for this, make sure that you read up on this conversion further.
P.S. I am still glad that I learned all the stuff about modifying cars on these forums. But as soon as the lease on my daily driver is over, I am trading my Z in for an FJ Cruiser (new DD) and next spring I am starting the FD LS1 project.
Used FD RX7 with high mileage and/or blown motor: 4000-5000$
LS1 engine/tranny combo: 6000-7000$
http://www.hinsonsupercars.com/FDTurnkey.htm :8700$
Having an awesome handling car that can run low 12's easy N/A (no chance of blowing the motor)-priceless.
Maybe a 350z with a TN ST is not a pinnocle of more then a century of automotive engineneering after all.
BTW, before you start flaming me for this, make sure that you read up on this conversion further.
P.S. I am still glad that I learned all the stuff about modifying cars on these forums. But as soon as the lease on my daily driver is over, I am trading my Z in for an FJ Cruiser (new DD) and next spring I am starting the FD LS1 project.
Why aren't you gone yet?FYI - I'm well aware of this swap. If I wanted an LSx I would have bought a z06.
Anyway, bye.
Last edited by taurran; 06-01-2006 at 03:21 PM.
06-01-2006, 03:20 PM
#128
Originally Posted by Oleg
Actually, I got the sticker shock from the price of the used Supras about an hour ago. Way too much, that I'll give you. But here is what my research has revealed:
Used FD RX7 with high mileage and/or blown motor: 4000-5000$
LS1 engine/tranny combo: 6000-7000$
http://www.hinsonsupercars.com/FDTurnkey.htm :8700$
Having an awesome handling car that can run low 12's easy N/A (no chance of blowing the motor)-priceless.
Maybe a 350z with a TN ST is not a pinnocle of more then a century of automotive engineneering after all.
BTW, before you start flaming me for this, make sure that you read up on this conversion further.
P.S. I am still glad that I learned all the stuff about modifying cars on these forums. But as soon as the lease on my daily driver is over, I am trading my Z in for an FJ Cruiser (new DD) and next spring I am starting the FD LS1 project.
Used FD RX7 with high mileage and/or blown motor: 4000-5000$
LS1 engine/tranny combo: 6000-7000$
http://www.hinsonsupercars.com/FDTurnkey.htm :8700$
Having an awesome handling car that can run low 12's easy N/A (no chance of blowing the motor)-priceless.
Maybe a 350z with a TN ST is not a pinnocle of more then a century of automotive engineneering after all.
BTW, before you start flaming me for this, make sure that you read up on this conversion further.
P.S. I am still glad that I learned all the stuff about modifying cars on these forums. But as soon as the lease on my daily driver is over, I am trading my Z in for an FJ Cruiser (new DD) and next spring I am starting the FD LS1 project.
06-01-2006, 03:23 PM
#129
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Originally Posted by overZealous1
oh ya, i do love a good hybrid, lol. another one to look at is the porschev. small block in a 911 or 914. the 911 with a small block has the same weight bias as a stock 911 turbo. think of the 0-60 times having the motor over the rear wheels and the torque of the V-8. been wanting to do it for years. also a slantnose widebody kit would be in order.
It would be fun, but I thing that the FD would be cheaper then the Porsche. Plus, the Posche body would have to be older and likely more expensive to restore...
But these guys can even stuff it into a 240SX...
06-01-2006, 03:28 PM
#130
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Originally Posted by taurran
Why aren't you gone yet?FYI - I'm well aware of this swap. If I wanted an LSx I would have bought a z06.
Anyway, bye.
I will leave it at this:
I want a fast car.
You want a fast 350Z.
Different goals.
Otherwise I don't understand why would anyone bypass the new Z06 in favor of the Z...
06-01-2006, 03:39 PM
#131
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Originally Posted by Oleg
Whatever...
I will leave it at this:
I want a fast car.
You want a fast 350Z.
Different goals.
Otherwise I don't understand why would anyone bypass the new Z06 in favor of the Z...
I will leave it at this:
I want a fast car.
You want a fast 350Z.
Different goals.
Otherwise I don't understand why would anyone bypass the new Z06 in favor of the Z...
And please leave it at that, you've taken enough from this thread.
06-01-2006, 03:52 PM
#132
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Originally Posted by taurran
True. I didn't say new c6 z06. A c5 is in the same price range as a new Z. I like the Z better overall.
I agree. I never cared for any pre-C6 vettes either (unless we are talking the classic ones from the 60's.
And please leave it at that, you've taken enough from this thread
Oh, god, what have I done?! Never in the annals of my350z.com has there ever been a thread hijack... Lets face it, given the history around here, it is a miracle that it stayed on topic for over 6 pages
I agree. I never cared for any pre-C6 vettes either (unless we are talking the classic ones from the 60's.
And please leave it at that, you've taken enough from this thread
Oh, god, what have I done?! Never in the annals of my350z.com has there ever been a thread hijack... Lets face it, given the history around here, it is a miracle that it stayed on topic for over 6 pages
...what was it again?
06-01-2006, 04:37 PM
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Originally Posted by overZealous1
yes guys with sleeves are having problems too. this is why i have been saying it is the head mostly creating the problem. this is also why i had such good luck with my head mod kit when i installed it. now the depth of the sleeves can help if they are sticking up higher than the rest of the block deck and act like an o-ring. this would put more pressure on the head to keep from flexing.
if you think about the direction of the combustion forces in the cylinder, the cylinder sees horizontal expansion, and the head and piston see vertical expansion. if the combustion chamber and piston head shape is correct, (and flat tops or dish styles are best with a center spark plug, all of which the VQ35 has) the horizontal forces should be equal on the cylinder walls.hence the areas that do not have a head stud holding the heads tight are the areas leaking. it is a process of elimination and taking a look at where the forces are applied to create this condition.
if you think about the direction of the combustion forces in the cylinder, the cylinder sees horizontal expansion, and the head and piston see vertical expansion. if the combustion chamber and piston head shape is correct, (and flat tops or dish styles are best with a center spark plug, all of which the VQ35 has) the horizontal forces should be equal on the cylinder walls.hence the areas that do not have a head stud holding the heads tight are the areas leaking. it is a process of elimination and taking a look at where the forces are applied to create this condition.
Regarding sleeved engines. I have seen deck's sink within the first 1k (anywhere from 0.005" to 0.012") miles, allowing coolant to be pushed. Its not that i dont think the 'head lifts' from the block, i just see it as a remote possibility when using a large 1/2" headstud! We find that once our Hp levels start to get beyond a joke - ie 750whp+ that even the best tuners cannot stop headgasket breach without a set of o-rings.
Other factors to consider, torque strength of studs. Some people swear by using ARP/OEM specification - 65ft/lbs on both our motors, other increase torque by ~10ft/lbs over stock. Some of the more successful tuners in our industry swear by oil lubed tourqe to 85ft/lbs!
Im not hear to provide all the answers, but share experience's
Like i said us Honda owners have been dealing with these issues for the last 10-15yrs. Open deck, its a love/hate relationship!ps.
Always re-check tourqe on headstuds after the first 5-10 heatcycles.
pss.
For the guys looking at swapping cars. Its not all about power, its also about weight
If u want something fast, look at a turbo k20 type-r. 400whp on a stock block. Only 4 pistons/rods/injectors to worry about and much lighter then any 350/supra will ever be. Sure its traction is hard in a FWD, but thats just part of the game :P
06-01-2006, 04:47 PM
#134
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Originally Posted by Weqster
Other factors to consider, torque strength of studs. Some people swear by using ARP/OEM specification - 65ft/lbs on both our motors, other increase torque by ~10ft/lbs over stock. Some of the more successful tuners in our industry swear by oil lubed tourqe to 85ft/lbs!
06-01-2006, 05:10 PM
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Originally Posted by overZealous1
think it's gunna be tough pushing a fwd in this forum, lol.
i love sliding the tail out in my Z. Not as exciting as a turbo honda, but hopefully an APS kit will fix that!
06-01-2006, 05:21 PM
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Originally Posted by Weqster
ps.
Always re-check tourqe on headstuds after the first 5-10 heatcycles.
Always re-check tourqe on headstuds after the first 5-10 heatcycles.
06-01-2006, 07:21 PM
#139
Originally Posted by taurran
And please leave it at that, you've taken enough from this thread.
he is a little pissed off right now.. let him blow off his steam..
when i tottaled my bike in 03.. i swore i would never ride another motorcycle... and then boom.. i end up spending $8k work on the motor.. so let him blow off his steam
06-01-2006, 07:48 PM
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Originally Posted by doug
being that the thread was about his motor blowing.. cut the guy a little slack
he is a little pissed off right now.. let him blow off his steam..
when i tottaled my bike in 03.. i swore i would never ride another motorcycle... and then boom.. i end up spending $8k work on the motor.. so let him blow off his steam
he is a little pissed off right now.. let him blow off his steam..
when i tottaled my bike in 03.. i swore i would never ride another motorcycle... and then boom.. i end up spending $8k work on the motor.. so let him blow off his steam
Thank you for intervention, but it was not me blowing my motor up (thank god). I would be really pissed if that happened.
I just made a comment that having this much $$ reserved for a FI Z project is ridiculous considering other options available on the market with other cars (unless you truly are a die-hard 350Z fanatic)... I have also expressed my gladness that this information became available BEFORE I made the mistake of sinking over 9 grand into the Z, while still being another 10 grand away from finishing the project (not counting a built motor) and possibly end up with a blown engine.
This did not offend anyone, except for mr. Taurran, who apparently believes that a Z with a TN ST is the mankind's crowning achievement.
