how much power can a properly repaced oem headgasket handle?

[queenskid926]

If a 7mgte had headgasket replaced the right way; cleaned the block and head, had the head machined flat, new stock headgasket with arp studs tq down to proper arp tq rating, How much power can it handle reliability?

Just looking for 350-400 hp for a few months while i save up for a build or swap.

Will a properly replaced hg and arp studs be enough for that power level?

 

[arizzle]

if its done properly ive seen a few here doing that much HP, but its just dependent on if its done properly, but i think a MHG would be better since everythings all out.

 

[shaeff]

Most of the issue is in the tune. If you have a properly torqued stock headgasket, and a GOOD, solid tune, you can run 400rwhp through it with no issues. Would I? No, but many, many people have done it in the past with zero issues.

 

[Nghty89]

The search button would yield results :sarcasm:

Go MHG for the safety since you are putting arp hardware in anyways and getting it machined. Do it once, Do it right, and you wont need to worry about what upgrades will cause that gasket to fail.

The stock one can hold a bit, depending on your tune. It's not HP that kills the gasket, it's detonation at the wrong point :naughty: aka a bad tune

 

[queenskid926]

i think a MHG would be better since everythings all out.

Not everything is going to be all out. Just the head will b., The block will remain in the car. I've heard and witness some ppl running a mhg with just machining the head but thats to risky for me to attempt.

Most of the issue is in the tune. If you have a properly torqued stock headgasket, and a GOOD, solid tune, you can run 400rwhp through it with no issues. Would I? No, but many, many people have done it in the past with zero issues.

Its just going to be a 57trim ct26. 550's. lexus afm, afc and mkiv fuel pump. Thats it just small little bolt-ons 16-17psi. Conservative.

Again this motor is not getting a full build on it. Just A little bit of fun and reliability. I have a spare 7mgte that I plan on building up, Internals, mhg etc etc but im also still contemplating on a swap so will see.

So I can pretty much say that a stock headgasket with arp hardware tq down correctly can hold 400hp daily driven?

 

[jdub]

If you're not going to machine the block, an OEM HG is a good choice. I'd give it a couple coats of copper spray, let it tack up, and lay it down on the block.

ARP studs are an excellent choice. Torque to ARP spec on the sheet that comes with them...use ARP moly lube and that spec (motor oil for lube is different). To set proper preload, do 5 torque down/loosen cycles per ARP recommendations...I would go to 75 ft/lbs on the 1st 4 cycles, setting 80 ft/lbs on the 5th.

Make sure you use the TSRM torque sequence. If you remove the cams to make getting to the stud nuts easier, they also have a specific torque sequence.

Using an OEM HG, I would definitely do a re-torque after 5 motor heat-up/cool-down cycles.

 

[IJ.]

Back when I had my 3.4L TTV8 Toyota in the 240z with twin hiflo T04's I ran 30 Psi on genuine Toyota Composite HG's, the secret was keeping it out of DETONATION.

I ran very low Compression Pistons Methanol injection and no InterCooler.
(engine was o-ringed as well but would still spit out gaskets if it was rattled at all)

 

[queenskid926]

thank you IJ and Jdub for the info. Its greatly appreciated.

 

[83suprapower]

I dont mean to thread jack ,please forgive me.I have a question. I have a cometic MLS headgasket im going to be put on soon. I had the head decked but the block is just cleaned and NO pitting and i got it smooth just not machined. IS it a good idea to use this gasket. Should i buy a OEM gasket or should i definately machine the block if i go MLS?

 

[jdub]

The Cometic MHG requires a smoothness of RA50 or lower. Installing it on a block that has not been machined is a crap shoot. And, you should never use a spray (copper) sealer on a new MHG...it attacks the factory Viton coating. It's even more important that the block deck checks out flatness wise.

 

[83suprapower]

ok so my question is if the block surface checks out straight, how can i figure out the RA rating i looked for info on that but couldnt find out how to figure it out.Thanks Jdub. im doing my headgasket tuesday so i just need to know what is the best bet. I dont wanna tear this thing apart in a month. But i really dont have the money to get it machined.so would i be better off buying an OEM?

 

[jdub]

You need a tester to determine RA...they are rather expensive

Safe bet is a OEM HG...you will be able to hold boost (properly torqued) to the limit of a CT26 (or fuel cut) without problems. My previous posts apply though

 

[83suprapower]

thanks alot! I appreciate all the info