Our theory on stock rod failure...
05-31-2006, 12:04 AM
#21
something else, how many miles were on these engines? How much were they abused before going FI?
oh I definetly think going over 400whp is a risky venture on a stock block. All you can do is try to minimize your risk and hope you got yourself a good engine. Obviously how hard and often you drive will have an effect on things too. Still though, a built block will cost as much as going FI which is expensive enough to swallow in one gulp.
I know if I blow up my engine right now, I'd actually probably wait a while before buying a built engine just cause it seems like there's been a lot of leaps and bounds with the VQ. People are now more aware of head lift issues, it does seem possible to rev to 8000 rpms afterall, there's more people building built VQ35's now, there's more (and cheaper) parts available, people are now boring out to 3.6 or 3.8 liters - so many more things going on now than there was a year ago. Now that people are running some of these new setups, I want to wait and see how they turn out before dumping money into a built engine. I don't want to later go "oh crap, I should have bought this or that instead" when I was building the engine cause that's way more expensive and involved than adding some other accessory thing to your FI kit or even taking your FI kit back off
I think all the things mentioned are all strong possibilities for the engine to fail and that in most cases it probably is a small chain reaction.
Some people have been running FI on their stock block for 30k miles with 10psi and others running 5.6 psi are blowing up after 2000 miles - though rarer these days. IMO the type of FI you run will have an effect on it too. A turbo running 8psi from 3000-redline is overall putting more stress on an engine than a vortech running 3psi at 3000 and 10 psi at redline. Even though it runs higher psi, it's so brief - even with parasitic loss factored in.
I've been getting the impression that breaking rods seems to be how turbos blow up engines, while superchargers have issues with the pistons going out - though rods can break too. I might be wrong, but I think that's interesting at least
Originally Posted by Wired 24/7
Call me an idiot/noob/naive or whatever. But where are all the people claiming that the stock block is good to 400+whp with a good tune? I am waiting for them to come in and raise the BS flag and tell us what they think REALLY happened to the TT motor.
I've heard more stories about bent or broken rods than i'd care to repeat. For my money I'd spend a little extra and do the minor engine buildup, even if you are going for ~400whp.
Subscribed so I can link to this thread next time someone says 400whp on a stock block is safe.
I've heard more stories about bent or broken rods than i'd care to repeat. For my money I'd spend a little extra and do the minor engine buildup, even if you are going for ~400whp.
Subscribed so I can link to this thread next time someone says 400whp on a stock block is safe.
oh I definetly think going over 400whp is a risky venture on a stock block. All you can do is try to minimize your risk and hope you got yourself a good engine. Obviously how hard and often you drive will have an effect on things too. Still though, a built block will cost as much as going FI which is expensive enough to swallow in one gulp.
I know if I blow up my engine right now, I'd actually probably wait a while before buying a built engine just cause it seems like there's been a lot of leaps and bounds with the VQ. People are now more aware of head lift issues, it does seem possible to rev to 8000 rpms afterall, there's more people building built VQ35's now, there's more (and cheaper) parts available, people are now boring out to 3.6 or 3.8 liters - so many more things going on now than there was a year ago. Now that people are running some of these new setups, I want to wait and see how they turn out before dumping money into a built engine. I don't want to later go "oh crap, I should have bought this or that instead" when I was building the engine cause that's way more expensive and involved than adding some other accessory thing to your FI kit or even taking your FI kit back off
I think all the things mentioned are all strong possibilities for the engine to fail and that in most cases it probably is a small chain reaction.
Some people have been running FI on their stock block for 30k miles with 10psi and others running 5.6 psi are blowing up after 2000 miles - though rarer these days. IMO the type of FI you run will have an effect on it too. A turbo running 8psi from 3000-redline is overall putting more stress on an engine than a vortech running 3psi at 3000 and 10 psi at redline. Even though it runs higher psi, it's so brief - even with parasitic loss factored in.
I've been getting the impression that breaking rods seems to be how turbos blow up engines, while superchargers have issues with the pistons going out - though rods can break too. I might be wrong, but I think that's interesting at least
Last edited by sentry65; 05-31-2006 at 12:16 AM.
05-31-2006, 12:30 AM
#22
I get your point(s) but IIRC there are literally people who just say "you'll be fine with a good tune" and leave it at that. A rather irresponsible statement if the fine print is, was, and should always be "but you should be prepared to replace your block if it should blow"
Am I wrong that you get money back for a good block (core exchange) but not for a blown motor? Perhaps it depends on the severity of the damage, I don't know.
I agree that people have different levels of acceptable risk. But come on, in this thread https://my350z.com/forum/forced-induction/193038-recomendations-on-a-dd-twin-turbo.html
Taurran you seem to be advocating people "not worrying" about a blown motor and not having a backup plan. People should mod responsibly, and not have to take out a second damn mortgage to pay for a blown motor. I would think if someone like Zilvia starts asking questions such as "can I run a really conservative tune to keep the motor from going BOOM" then replacing a blown motor might be more than they can handle. I don't know, but I wouldn't be telling them "oh, you'll be fine..." I would say "you'll be fine... as long as replacing the stock motor would not financially burden you" etc.
Plus we are talking about a daily driver in that thread, a car which, should it explode, would cause collateral financial damages of buying a cheap beater or renting, while the Z is in for long and ghastly repairs.
chimmike says 400-450whp is PERFECTLY SAFE with the right maintenance. That kind of statement is simply not true. Hell I bought my EU off of someone who bent a rod on the dyno before they could even tune the car because it blew, and at low RPMs IIRc.
I'm not fighting with you here, I think we're having quite a constructive discussion.
Talk may be cheap but I have set out to do 100% of what I said I will do with my Z. Maybe i have not spent 20k like some people, but I don't bullsh1t around and tell people what I would do just because I think I'm smart or something. When I say "I would do X" that is what I would really do, me, mike, wired 24/7...
I have never said I am going F/I for sure. But I will say this right here, right now... if I go F/I (a definite possibility) it will be a daily driver and I will be getting a built motor.
I appreciate that you and a lot of other people have real life experience with forced induction on the Z. But (please correct me if I'm wrong) aren't not all Z motors built the same? I thought pistons of loose tolerances are matched as best they can at the factory to fit the cylinders into which they will reside, rather than having tight tolerance, uniformly sized pistons as one would use in a built motor. This among other things, like the rods seeming to be a serious weak link in our stock motors... the crank not being balanced to tight enough specs means yet another inconsistency...
Am I wrong that you get money back for a good block (core exchange) but not for a blown motor? Perhaps it depends on the severity of the damage, I don't know.
I agree that people have different levels of acceptable risk. But come on, in this thread https://my350z.com/forum/forced-induction/193038-recomendations-on-a-dd-twin-turbo.html
Taurran you seem to be advocating people "not worrying" about a blown motor and not having a backup plan. People should mod responsibly, and not have to take out a second damn mortgage to pay for a blown motor. I would think if someone like Zilvia starts asking questions such as "can I run a really conservative tune to keep the motor from going BOOM" then replacing a blown motor might be more than they can handle. I don't know, but I wouldn't be telling them "oh, you'll be fine..." I would say "you'll be fine... as long as replacing the stock motor would not financially burden you" etc.
Plus we are talking about a daily driver in that thread, a car which, should it explode, would cause collateral financial damages of buying a cheap beater or renting, while the Z is in for long and ghastly repairs.
chimmike says 400-450whp is PERFECTLY SAFE with the right maintenance. That kind of statement is simply not true. Hell I bought my EU off of someone who bent a rod on the dyno before they could even tune the car because it blew, and at low RPMs IIRc.
I'm not fighting with you here, I think we're having quite a constructive discussion.
Talk may be cheap but I have set out to do 100% of what I said I will do with my Z. Maybe i have not spent 20k like some people, but I don't bullsh1t around and tell people what I would do just because I think I'm smart or something. When I say "I would do X" that is what I would really do, me, mike, wired 24/7...
I have never said I am going F/I for sure. But I will say this right here, right now... if I go F/I (a definite possibility) it will be a daily driver and I will be getting a built motor.
I appreciate that you and a lot of other people have real life experience with forced induction on the Z. But (please correct me if I'm wrong) aren't not all Z motors built the same? I thought pistons of loose tolerances are matched as best they can at the factory to fit the cylinders into which they will reside, rather than having tight tolerance, uniformly sized pistons as one would use in a built motor. This among other things, like the rods seeming to be a serious weak link in our stock motors... the crank not being balanced to tight enough specs means yet another inconsistency...
Last edited by Wired 24/7; 05-31-2006 at 12:45 AM.
05-31-2006, 12:40 AM
#23
[QUOTE=single turbo dynod at 380 whp with a 13.0-13.5 A/F from 6000 to redline, way lean.
..[/QUOTE]
I'm running 14.5 A/F, but it's NA. Would it still be considered dangerous? I'm going with UTEC, but can't fork out the $ for the part and tuning right at this moment.
..[/QUOTE]
I'm running 14.5 A/F, but it's NA. Would it still be considered dangerous? I'm going with UTEC, but can't fork out the $ for the part and tuning right at this moment.
05-31-2006, 12:46 AM
#24
yeah I agree, FI isn't safe really no matter what. There's so many factors other than just a good safe tune. It's more like it being a good safe tune and the stars are alligned just right that you'll be safe.
I'm probably weird to think so, but I think anyone willing to dish out huge money to make their car possibly blow the engine should have an alternative available transportation other than their Z. Some sort of back up plan.
Yeah you can get some money for your core engine block - like $1500-2000 or whatever it is, but at the end of the day, to buy a medium built block, tearing off all the accessories and hoses, pull the engine out, bolt the heads back up, put the engine back in, put all the hoses and wires back on, shipping the old and new block etc, you're probably looking at $6000 minimum - and that's with the $1500-2000 core charge already getting back to you.
So yeah it's a better deal to do it all at once. But when you're talking about at least $6000, what's another $1500-2000? I guess that was my point in that other thread.
IMO having a FI Z as your only daily driver car that you rely on to get to your job is more of an issue at least to me than the possability of the engine blowing. Meaning I'd rather have a stock engine with FI and a backup car than a built engine with FI and no backup car - IMO. Cause even with a built block, who's to say something still won't go wrong?
I'm probably weird to think so, but I think anyone willing to dish out huge money to make their car possibly blow the engine should have an alternative available transportation other than their Z. Some sort of back up plan.
Yeah you can get some money for your core engine block - like $1500-2000 or whatever it is, but at the end of the day, to buy a medium built block, tearing off all the accessories and hoses, pull the engine out, bolt the heads back up, put the engine back in, put all the hoses and wires back on, shipping the old and new block etc, you're probably looking at $6000 minimum - and that's with the $1500-2000 core charge already getting back to you.
So yeah it's a better deal to do it all at once. But when you're talking about at least $6000, what's another $1500-2000? I guess that was my point in that other thread.
IMO having a FI Z as your only daily driver car that you rely on to get to your job is more of an issue at least to me than the possability of the engine blowing. Meaning I'd rather have a stock engine with FI and a backup car than a built engine with FI and no backup car - IMO. Cause even with a built block, who's to say something still won't go wrong?
05-31-2006, 01:19 AM
#25
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Yes, I think an FI kit is fine on a daily driven vehicle. However, I would never want to have it on my sole means of transportation. Your statement about not buying an FI kit unless you can pay 100% cash on a new motor is an overstatement. I agree that having "a plan" is a must, but advising people not to buy a kit unless they can throw $6000 under a mattress somewhere sounds a bit ridiculous to me.
However, I do notice I made a typo in that thread. I meant to state that I DO have a plan for worst case scenario. I could buy a fully built and sleeved longblock today in cash, but that doesn't mean I want to. Like Sentry, I plan on waiting it out a little until we see some technical advances with lower prices before doing so.
Now, I think this conversation is beginning to wander from the original intent of this thread. It wasn't made to be an economic discussion of blowing a stock motor, but rather a technical one...
However, I do notice I made a typo in that thread. I meant to state that I DO have a plan for worst case scenario. I could buy a fully built and sleeved longblock today in cash, but that doesn't mean I want to. Like Sentry, I plan on waiting it out a little until we see some technical advances with lower prices before doing so.
Now, I think this conversation is beginning to wander from the original intent of this thread. It wasn't made to be an economic discussion of blowing a stock motor, but rather a technical one...
Last edited by taurran; 05-31-2006 at 01:21 AM.
i hope my car comes out happy and safe *crosses fingers*
05-31-2006, 04:41 AM
#27
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Yeah reading this kinda makes me worried as my car will be tuned on Thursday! If there was headlift, wouldnt you be able to tell by looking at the headgasket?
05-31-2006, 04:47 AM
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nice write up...good to see someone concerned 
however...what would be an approperiate precaution to prevent this even of liquid "sneaking" into the combustion chamber? any solution for nonbuilt engines running ~8psi of boost?
however...what would be an approperiate precaution to prevent this even of liquid "sneaking" into the combustion chamber? any solution for nonbuilt engines running ~8psi of boost?
05-31-2006, 04:48 AM
#29
Originally Posted by Wired 24/7
Subscribed so I can link to this thread next time someone says 400whp on a stock block is safe.
05-31-2006, 04:59 AM
#30
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Originally Posted by doug
and the benefit of that would be? i am curious... do you N/A Owners come to the F/I forum to tell F/I owners that their cars are going to blow up?
lol I got a good laugh out of that one because when I went f/i it seems like thats all I heard from N/a owners.. "your engine is going to blow!"
Never once have I said 400whp is safe on the stock block, I only shared my experience and my experience was that on the stock engine my car was fine at 417whp even with 60k miles on it up until the time I sold it. Now, I always kept another car and funds for a built engine just in CASE, but it amazes me how hearsay triumphs real experience in the mind of some people.
MRC, thank you for the post.. my engine blew in the same manner but that is when the car was completely stock..
05-31-2006, 06:43 AM
#34
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I think MRC did a stand up thing for sharing with the community here.
I don't think this should steer people totally away from going f/i on the stock block, nor should it turn people away from building the block.
However, it does seem like doing a set of HGs and ARP studs would be the best idea for insurance (as well as -obviously- having the cash for as built motor in reserve or a spare car).
I'd personally like to know what, if anything was done to the heads previously? Were studs done? were the heads ever off the car? I know MRC stated that one car they did the tt kit install and the other they never touched previously... anyway of finding out who DID touch the motor on the single turbo car beforehand? This would give us all some more insight.
I don't think this should steer people totally away from going f/i on the stock block, nor should it turn people away from building the block.
However, it does seem like doing a set of HGs and ARP studs would be the best idea for insurance (as well as -obviously- having the cash for as built motor in reserve or a spare car).
I'd personally like to know what, if anything was done to the heads previously? Were studs done? were the heads ever off the car? I know MRC stated that one car they did the tt kit install and the other they never touched previously... anyway of finding out who DID touch the motor on the single turbo car beforehand? This would give us all some more insight.
05-31-2006, 06:44 AM
#35
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Originally Posted by paranormal
sorry im a newb to this headlift thing.. how do you detect it? like what are signs?
read up here. headlift has been the topic of many discussion the last few weeks.
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
05-31-2006, 06:51 AM
#36
how do those pistons look compared to the rest? they appear to be pretty clean, but if they match the other pistons, then i highly doubt there was water making it back into the cylinders.
on my first motor, when i pulled it apart, i had 5 bent rods and 4 pistons with broken ring lands. there was no indication of water making it back into the cylinder, especially enough to hydrolock like that. you would also hear a cylinder missing right before it happened, as the water would come in slow at first, then more and more.
the only possible way i could see this happening is if when the cylinder next to the problem cylinder lifted the head so far it pushed coolant into the cylinder next to it. if that was the case, the problem cylinder would then push water back into the other cylinder, and ultimately it should happen to the entire motor, not just end cylinders.
again, this is just my opinion, and i have seen some really weird stuff happen before. but i feel there may have been a split second timing glitch as the cylinders were right next to eachother in firing order.
on my first motor, when i pulled it apart, i had 5 bent rods and 4 pistons with broken ring lands. there was no indication of water making it back into the cylinder, especially enough to hydrolock like that. you would also hear a cylinder missing right before it happened, as the water would come in slow at first, then more and more.
the only possible way i could see this happening is if when the cylinder next to the problem cylinder lifted the head so far it pushed coolant into the cylinder next to it. if that was the case, the problem cylinder would then push water back into the other cylinder, and ultimately it should happen to the entire motor, not just end cylinders.
again, this is just my opinion, and i have seen some really weird stuff happen before. but i feel there may have been a split second timing glitch as the cylinders were right next to eachother in firing order.
05-31-2006, 06:56 AM
#37
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Originally Posted by sq40
I think I have been completly talked out of ever going FI for my car. I was considering just a basic Vortech kit.. But now...
05-31-2006, 07:00 AM
#38
also, in almost every case, the bent rod issue is happening in stock block motors. in alot higher boost conditions and only the addition of stock sized arp bolts (to this point atleast) the hydrolock would be happening alot more on the built blocks. it wouldn't matter if you had a stock rod or a pauter, the water would not compress and you would get devastation.
again, just my opinion, lol.
again, just my opinion, lol.
05-31-2006, 07:28 AM
#39
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Originally Posted by Gman2004
paranormal,
read up here. headlift has been the topic of many discussion the last few weeks.
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
read up here. headlift has been the topic of many discussion the last few weeks.
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
https://my350z.com/forum/showthread....light=headlift
thanks man. im going with the l19 head studs this time around
05-31-2006, 07:30 AM
#40
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Please explain the head lift cycle. When is water pressure so high as to enter cylinder. How much head lift per cycle is required to pass ounces of water? Can a stuck injecter pass ounces of fuel in this time?