Okay, so the only thing I plan to do is replace my head gasket, replace the stock bolts with ARP bolts, and torque them to 75 pounds. How much boost can I run safely with just doing this and without rebuilding my bottom end?
How many pounds of boost can you run on a (mostly) stock 7M-GTE SAFELY?
- Thread starter Sizzlinninja
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arp torque spec is 90 for the head bolts. what type of head gasket are you going to put in? if your on the stock ct then you are limited to about 12-14 psi were it loses it efficiency IIRC. anybody correct me if im wrong
ARP specs for head BOLTS are 75 ft lbs as show below. Note the Aluminum value is used for this application.
I think the question is.. how many PSI can you throw at a stock 7MGTE before your risking the engine integrity. Im curious as well as I have a rebuilt 7MGTE (built stock though with a non-OEM, non-metal headgasket (cant recall, but I think its Cometic). Im running a 57 Trim with 550 injectors (no upgraded intercooler), AEM UEGO Wideband, AFPR, Lexus AFM (LIPP) and a 3" full exhaust (turbo-back). Using a HKS EVC-S boost controller (stock BOV and turbo has internal wastegate).
I am curious as well as to what I should limit myself on PSI (regardless of turbo capability) before I start risking headgasket failure (or other problems). What is safe for a "non-built" 7MGTE?
Also, in regards to head torquing, I was under the impression the 7MGTE Head needed 90 ft/lbs on our aluminum heads as well. I have been told that if your fussy, you should start at 75 ft/lbs, run the engine until it heats, torque to 80, let it sit overnight.. run until hot, torque to 85, let it sit overnight.. and then torque to 90. (The idea was that it would take into account the thermal expansion variance between the aluminum head and the cast block. However.. that may just be silly talk).
I have also heard 95 ft/lbs and 110 ft/lbs for ARP Studs... can get confusing.. lol.
also.. for what its worth.. you might want to consider studs as opposed to bolts. Although, I am not a mechanic and running on community "heresay".
I am curious as well as to what I should limit myself on PSI (regardless of turbo capability) before I start risking headgasket failure (or other problems). What is safe for a "non-built" 7MGTE?
Also, in regards to head torquing, I was under the impression the 7MGTE Head needed 90 ft/lbs on our aluminum heads as well. I have been told that if your fussy, you should start at 75 ft/lbs, run the engine until it heats, torque to 80, let it sit overnight.. run until hot, torque to 85, let it sit overnight.. and then torque to 90. (The idea was that it would take into account the thermal expansion variance between the aluminum head and the cast block. However.. that may just be silly talk).
I have also heard 95 ft/lbs and 110 ft/lbs for ARP Studs... can get confusing.. lol.
also.. for what its worth.. you might want to consider studs as opposed to bolts. Although, I am not a mechanic and running on community "heresay".
The amount of psi you can throw at it will change for every setup....
It's all in the tune on how your car will hold up
There are stock 7m's with mhg's running 30psi and 700+ whp
It's all in the tune on how your car will hold up
There are stock 7m's with mhg's running 30psi and 700+ whp
10 psi (if doable without fuel cut) is okay on a stocker just by shimming the wastegate to achieve it. Depends on your altitude really and overall engine condition.
But is there a number for a healthy 7MGTE that is built for the stock boost only (aka, rebuilt without thought given to 500+ HP) that it can take without much worry? I was thinking of targeting 12 psi for daily and 19 psi for fun. (I dont see any reason to go above 19 psi because I am not going to a track with my car... its all personaly feel).
Was wondering if a stock 7MGTE can handle 19 psi if you can actually feed it. (I dont think I could achieve it without the upgrades I have external to the bottom end.. just wondering if the headgasket will hold and assume that is what the OP is asking)
But is there a number for a healthy 7MGTE that is built for the stock boost only (aka, rebuilt without thought given to 500+ HP) that it can take without much worry? I was thinking of targeting 12 psi for daily and 19 psi for fun. (I dont see any reason to go above 19 psi because I am not going to a track with my car... its all personaly feel).
Was wondering if a stock 7MGTE can handle 19 psi if you can actually feed it. (I dont think I could achieve it without the upgrades I have external to the bottom end.. just wondering if the headgasket will hold and assume that is what the OP is asking)
I ran 22psi on a 60-1 bottom end was fine car made great power
This was a 100% stock 7mgte block
Had a composite head gasket with arp head studs and a fully rebuilt head
This was a 100% stock 7mgte block
Had a composite head gasket with arp head studs and a fully rebuilt head
how about without ARP Head studs (or bolts) and not a fully rebuilt (ported) head?
My worry is that the stock headbolts will stretch if overboosted over time.
My worry is that the stock headbolts will stretch if overboosted over time.
I've heard that the stock bolts are as strong as arp head bolts as long as they are torqued correctly you should be fine.
The head doesn't matter as long as the head was decked.
The head doesn't matter as long as the head was decked.
A good reason not to go too crazy on head bolt torque is that the head isn't that strong....
http://www.supraforums.com/forum/showthread.php?683040-finally-an-answer-to-the-7m-head-gasket-issue
http://www.supraforums.com/forum/showthread.php?683040-finally-an-answer-to-the-7m-head-gasket-issue
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what if that's why Toyota torqued the head bolts so low is cuz they knew the head was mushy Sent From My HTC One S using Tapatalk 2
Yeah, I've often thought that.
By the way stock head bolts tensile strength=160,550 PSI (measured by Reg Reimer years ago) and ARPs are 190,000 PSI, so as JJ says, very little difference to the point where it doesn't matter.
By the way stock head bolts tensile strength=160,550 PSI (measured by Reg Reimer years ago) and ARPs are 190,000 PSI, so as JJ says, very little difference to the point where it doesn't matter.
"How long is a piece of string"....
Toyota specced an asbestos based HG way back, it required 58ft/lbs, they changed to a non asbetos gasket but didn't address the fact it needed more clamp to achieve the same seal.
As for the Rod Bolts, if you change them the rods need resizing, if you're that deep into an engine you're NOT going to chance unknown 20 year old bolts when the ARP's are so cheap.
Toyota specced an asbestos based HG way back, it required 58ft/lbs, they changed to a non asbetos gasket but didn't address the fact it needed more clamp to achieve the same seal.
As for the Rod Bolts, if you change them the rods need resizing, if you're that deep into an engine you're NOT going to chance unknown 20 year old bolts when the ARP's are so cheap.
23 psi here on stock turbo (yes i know its past effiency range)
maft pro, walbro 255, spearco fmic, 2.5in IC pipes, 3in ex, speed density, afpr, wideband...etc
stock headgasket held up great(unknown if it was retorqued)...in process of replacing headgasket as we speak due to overheating(failed fan clutch)
So what JJ and TurboHabanero are saying is people are spending $100+ on aftermarket headstuds that are just a little more stronger but also give the headache if the allen head is stripped
Does anybody have Ron's write up on this?
maft pro, walbro 255, spearco fmic, 2.5in IC pipes, 3in ex, speed density, afpr, wideband...etc
stock headgasket held up great(unknown if it was retorqued)...in process of replacing headgasket as we speak due to overheating(failed fan clutch)
So what JJ and TurboHabanero are saying is people are spending $100+ on aftermarket headstuds that are just a little more stronger but also give the headache if the allen head is stripped
Does anybody have Ron's write up on this?
This is all very good info. Reading the difficulty (which makes a lot of sense) on the exhaust side was a good brain starter as well. I knew there was issues when your engine overheated but never thought about how touchy it was going to be.
A strong 7M is basically dependant on 2 things, the builder and the maintainer... more so than what I am used to from my teen years. (that was a long time ago btw)
We push our engines hard with our "cool" upgrades, so the failures are always going to be more plentiful. Prevention can be as simple as being informed and not sitting on your thumbs.
I always wondered how an aluminum head was supposed to hold up to 100+ ft/lbs of torque when I have seen so many pictures of stress fractures around the holes.
A strong 7M is basically dependant on 2 things, the builder and the maintainer... more so than what I am used to from my teen years. (that was a long time ago btw)
We push our engines hard with our "cool" upgrades, so the failures are always going to be more plentiful. Prevention can be as simple as being informed and not sitting on your thumbs.
I always wondered how an aluminum head was supposed to hold up to 100+ ft/lbs of torque when I have seen so many pictures of stress fractures around the holes.
Head studs give better tension uniformity than bolts, that is a fact. Whenever you dig into an engineering problem, there will be questions that cannot be fully answered and decisions that will be compromises. Just a fact of life.