How much boost is too much?

[Heatmiser]

I have rebuilt my 7mgte with stock internals about 1k on rebuild...and i should have but did not "coat" internals...

added:
550cc inj
60-1 trim ct-26
HKS VPC
SAFC
spearco intercooler w/larger I.C.piping - not sure what size -
3inch d.p. and exhaust - currently running test pipe.

my question, how much H.P. / boost can the 7mgte stand with stock internals and last more than just say 10k - essentially, i don't want to kill it ANYTIME soon, but want to run as much boost as it will safely take...

thanks

 

[Fletch124]

15psi is about the end of the Ct's efficiency range.

 

[Facime]

Turn it up until it explodes then back it down a smidge

seriously though it just depends on a lot of things. Fuel system/octane, timing/tuning, heat reduction/scavaging. As already shown in another thread, properly built the stock bottom end can take alot more than most people give it credit for. My guess is that you could reach the end of the CT26's useability range before you exceed the internals...again it depends on how well built it is. Since you are running piggyback with reasonable mods, I would say 12-15lbs of boost would be a good estimate.

 

[Quin]

15psi is about the end of the Ct's efficiency range.

Reading comprehension just pwned you. A 60-1 is good for a good bit more than that. What's your compression ratio, what HG are you using, how good is your tune, what fuel are you using?

There are really too many variables to say this, but we need to know more to even give a good estimate.

 

[Davismj711]

Heat I am sure many will ask if during your rebuild you did appropriate head, and block work, and installed a metal head gasket with correct torque specs.

As for max boost I am not certain as I prefer to stay on the lame end, I would prefer my rebuild lasts a bit more than 10K ^^

 

[MOTOWNMKIII]

umm. 60-1 CT.....

 

[MOTOWNMKIII]

damn, beat me to it. you guys are fast

 

[Heatmiser]

yes, arp studs and a metal hg. (trq to 80 ft lbs), compression ratio ? run 93 pump gas...

i did have to sleeve the two rear cylinders though... all else in spec.

 

[suprahero]

If you really want it to last more than ten thousand miles, then I"d say you should be safe with six pounds of boost on a daily basis............:icon_roll

 

[tlo86]

i did have to sleeve the two rear cylinders though... all else in spec.

will be good for 10psi. maybe 8... ever consider a new engine?

 

[quake]

where do you guys get these #'s from? Just tune it properly and live with what you got. Don't do much part throttle boosting with the stock ecu. I would keep it under 15psi with that set up. I run 18psi every day on a larger turbo running a standalone but that is what i tuned it for. I just hit 6000 miles, 6000 hard miles...

 

[Heatmiser]

Thanks for the resp. - i will probably run around 12-14lbs. that seems pretty safe based on what most responded - plus, i won't be pushing it really hard alot anyways...

thanks guys

 

[MKIIINA]

where do you guys get these #'s from? Just tune it properly and live with what you got. Don't do much part throttle boosting with the stock ecu. I would keep it under 15psi with that set up. I run 18psi every day on a larger turbo running a standalone but that is what i tuned it for. I just hit 6000 miles, 6000 hard miles...

The numbers they are pulling work like this. The harder you push something the shorter the time it will go between breaks. I ran my car at 18+ psi on a stock CT26, SP61GT, and now a JT61GT. Will my car show more wear than a stock boost stock car with a similiar amount of miles? More than likely. The 60-1 has a better efficiency at slightly elevated boost levels (14-18+ psi) where the stocker tends to run out of breath at 15+ psi.

to the OP 12-16 psi should last you for a good long while. things start to come apart more quickly at about 400rwhp. but remember that if you run shitty gas and detonate all bets are off, same with running lean. Heck you could kill a stock NA by just dumping the oil out of it and revving until it explodes.

Turn it up until it explodes then back it down a smidge ...

my thoughts exactly! :biglaugh:

 

[suprahabsfan]

If you rebuilt your engine with pistons and all then for the first couple thousand miles any boost is too much! You need to be more worried about the rings seating.

That being said, my buddy has a 60-1, same setup as you, and he ran 21psi for four years until he bought a truck and made it his daily driver. That was on a 120,000 mile engine. Didn't drive hard all the time but a lot of the time! ::naughty:

 

[Heatmiser]

If you rebuilt your engine with pistons and all then for the first couple thousand miles any boost is too much! You need to be more worried about the rings seating.

That being said, my buddy has a 60-1, same setup as you, and he ran 21psi for four years until he bought a truck and made it his daily driver. That was on a 120,000 mile engine. Didn't drive hard all the time but a lot of the time! ::naughty:

sounds like i'll be good then... thanks

 

[selfinfliction]

If you rebuilt your engine with pistons and all then for the first couple thousand miles any boost is too much! You need to be more worried about the rings seating.

:biglaugh:

finish build
leave under small load at varying speeds for 20 minutes, then hammer down

engine broke in

 

[MKIIINA]

/\ lets not get into that arguement in this thread....

 

[suprahabsfan]

No, no argument. You should drive under varying rpm's, but not at full throttle.