running 10psi...? 
running 10psi...?
12 Second Truck Club
Joined: Feb 2002
Posts: 5,574
Likes: 0
From: Sacramento, CA
Originally Posted by seabirdak
Why do you need to build up the motor?
That being said it's all gona depend on your combo because 10psi isn't always 10psi.
If you are making 650 at the crank, which you should at 10psi, then I would expect issues with the stock bottom end. F8LZ71 is right. If you want it to live, then build your motor to hold 10 or run less psi if you dont want to build it. You can run meth injection instead of FMIC, but IMO, I like the intercooler. You can always run the meth and intercooler.
I ran 10# on my stock bottom with money set aside for the new shortblock. It lasted a few months and that was with "mostly" conservative driving. Finaly blew it up racing a S/C Saleen. Your stock block will not last at 10#, the pistons are just too weak. When your dipstick pops out or you start blowing smoke thats when its time to bust out the wallet.
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Verdad Gallardo 12 Second Truck Club
Joined: Feb 2002
Posts: 5,574
Likes: 0
From: Sacramento, CA
Originally Posted by parish8
my experience sugests 10psi would be fine for a very long time on a stock botom end. the right tune and fuel(or meth injection) is the key.
Truck or car? There is a difference there
You can run 10 psi on the stock bottom end, but you need to setup the upperhalf and tune of the motor properly.
What wipes out these hyper-weak pistons is detonation. They don't take well to it. Many folks will run 10 psi on a detonation prone engine (ie at stock static compression ratio), and blame the bottom end for falling apart. Run a conservative compression, a safe tune (timing very low), fueling rich, intercooling, proper squish, etc... and you should be fine.
Its all in the setup. The stock bottem-ends on these cars will put up with a lot of punishment, just not any detonation.
What wipes out these hyper-weak pistons is detonation. They don't take well to it. Many folks will run 10 psi on a detonation prone engine (ie at stock static compression ratio), and blame the bottom end for falling apart. Run a conservative compression, a safe tune (timing very low), fueling rich, intercooling, proper squish, etc... and you should be fine.
Its all in the setup. The stock bottem-ends on these cars will put up with a lot of punishment, just not any detonation.
12 Second Truck Club
Joined: Feb 2002
Posts: 5,574
Likes: 0
From: Sacramento, CA
I still disagree in general terms. The average person is not going to monitor their vehicle like you do so they won't be as apt to make changes on the fly to keep the tune perfect. The usual case is they have someone do a tune for them and it's either going to be hot and blow up fast or it's going to be really safe and not put out the power to it's fullest potential in which case see my 2nd reply.
I never said it can't be done. Far from it. I think I could have ran 10psi on my truck for a VERY long time. It's just the average Joe probably won't go through all the precautions needed to keep it together for a long life.
I'd rather tell someone they need to beef things up and let them down now rather than have them spend all they extra cash they have to get big HP only to break in a couple months (if things don't go right) and not be able to afford to get things fixed.
I never said it can't be done. Far from it. I think I could have ran 10psi on my truck for a VERY long time. It's just the average Joe probably won't go through all the precautions needed to keep it together for a long life.
I'd rather tell someone they need to beef things up and let them down now rather than have them spend all they extra cash they have to get big HP only to break in a couple months (if things don't go right) and not be able to afford to get things fixed.
well, i can't argue with that. to answer his question.
you can go with all that stuff listed above to handle 10psi
or, you can do nothing other than the right fuel or meth and keep a VERY close eye on your tune.
to be honest i didn't really watch my tune that close. any time i bumped it up i hooked up the lap top and if it looked ok then i didn't watch anything till i turned it up again(usualy just a few days later
)
even with the good parts you are going to spit out a head gasket or something if your tune is off so keeping a close eye on your tune is something your going to have to do no matter what.
you can go with all that stuff listed above to handle 10psi
or, you can do nothing other than the right fuel or meth and keep a VERY close eye on your tune.
to be honest i didn't really watch my tune that close. any time i bumped it up i hooked up the lap top and if it looked ok then i didn't watch anything till i turned it up again(usualy just a few days later
)even with the good parts you are going to spit out a head gasket or something if your tune is off so keeping a close eye on your tune is something your going to have to do no matter what.
12 Second Truck Club
Joined: Feb 2002
Posts: 5,574
Likes: 0
From: Sacramento, CA
Originally Posted by seabirdak
what's the max psi you can run with a stock block?
You're asking the wrong question.
You should be asking what's the max HP you can run on the stock short block.
PSI is not a constant measure. change a cam slightly or exhaust configuation and you change PSI.
TECH Resident
Joined: Sep 2004
Posts: 756
Likes: 20
From: Cali
I'd have to agree alot with what was said previously.. I am planning on running roughly 9psi on my completely stock 5.3(which in fact has a decent amount of miles).. It run very stong and flawless, so I'm not worried going into it....
It's all in the Tune, like what was said before. I did the intercooler to keep temps down and such, and the fuel will be more than suffiecient, so a GOOD tune is inevitable.
It's not like my 10psi setup is going to push the same numbers as a cammed 5.3, with heads and worked over motor, but it's all in the actual HP that the overall engine is pushing... not just the resistence the turbo/blower has(as in the psi)
It's all in the Tune, like what was said before. I did the intercooler to keep temps down and such, and the fuel will be more than suffiecient, so a GOOD tune is inevitable.
It's not like my 10psi setup is going to push the same numbers as a cammed 5.3, with heads and worked over motor, but it's all in the actual HP that the overall engine is pushing... not just the resistence the turbo/blower has(as in the psi)
