Boost on replacement OEM headgasket and OEM headbolts?

[hock2k5]

Yo,

Im finally getting my supra back after my toyota mech. checked it out (a family friend)

Its a JDM 7MGTE, 45k miles, 3" Blitz turboback exhaust, ACT lightwight flywheel, centerforce stage3 clutch, kyb gr2 struts, eibach springs....i purchased the car this way.

my question...after searching for days is....is it just the original headgasket that sucks, or can the replacement OEM headgasket with OEM headbolts handle much boost.

Any reply would be great,

Thanks,

Adam

 

[supra90turbo]

yo,

search.

thanks,
Kurt.






































try that. it should point you in the right direction as to the information you're looking for.

 

[abustiffy]

tuning tuning tuning. If you detonate, just about any amount of boost can kill it. I think as long as things are happy in the chamber, a stock headgasket and bolts, torqued to the right torque(over stock) It will withstand anything the stock turbo can dish out. That doesnt mean crank that shit up on a stock fuel system and bitch when things go wrong and call the car a cheap pos.

 

[hock2k5]

tuning tuning tuning. If you detonate, just about any amount of boost can kill it. I think as long as things are happy in the chamber, a stock headgasket and bolts, torqued to the right torque(over stock) It will withstand anything the stock turbo can dish out. That doesnt mean crank that shit up on a stock fuel system and bitch when things go wrong and call the car a cheap pos.

is an OEM replacement headgasket stronger then the original? or no?

I realize i need tuning, fuel, etc etc.....but that really wasn't my question.

thanks for the serious replys though.

 

[abustiffy]

low torque spec is a main downfall of a 100% factory vehicle.

 

[jdub]

Toyota = OEM
Toyota did revise the stock HG, but it's still made of a composite graphite material. I would use ARP bolts torqued to 75 ft/lbs on a stock HG. It can actually handle quite a bit of boost...you can take it up to fuel cut without a problem if you use the ARP bolts. If you stick with the OEM head bolts, still torque to 75 ft/lbs.

 

[abustiffy]

Toyota = OEM
Toyota did revise the stock HG, but it's still made of a composite graphite material. I would use ARP bolts torqued to 75 ft/lbs on a stock HG. It can actually handle quite a bit of boost...you can take it up to fuel cut without a problem if you use the ARP bolts.

DURR. I was going to mention ARPs but that slipped my mind. It is a worthwhile upgrade imo.

 

[hock2k5]

Toyota = OEM
Toyota did revise the stock HG, but it's still made of a composite graphite material. I would use ARP bolts torqued to 75 ft/lbs on a stock HG. It can actually handle quite a bit of boost...you can take it up to fuel cut without a problem if you use the ARP bolts. If you stick with the OEM head bolts, still torque to 75 ft/lbs.

Perfect....answers that i was looking for.

I'm obviously not looking to do anything crazy ATM, just wanted some info. I purchased my car, and they replaced the the JDM headgasket with an OEM headgasket which isn't what it seems like most people do here. Instead of tearing the engine apart to change the headgasket again, I would rather just run conservative on what pressure an OEM replacement can do.

I'll have to check the tq, and possible replace the OEM bolts with ARP's.

Thanks for the serious replies..... :icon_bigg

 

[johnathan1]

Replace EVERY part of the cooling system when you replace the headgasket, and it should last a long time. I am running ~11.5psi on stock headgasket, my only mods are intake, exhaust, and a MBC.

 

[hock2k5]

Replace EVERY part of the cooling system when you replace the headgasket, and it should last a long time. I am running ~11.5psi on stock headgasket, my only mods are intake, exhaust, and a MBC.

The radiator is replaced already...i will have to check out everything else.

 

[Adjuster]

Just my .02, but if your going to the trouble of buying bolts, ditch that and get studs. (The cost difference is not that much, and the studs you can re-use many times, and are better in our application.)

ON the gasket issue, it's really dependant on how much boost you run, how correct your state of tune is, and the quality of your gas.

I ran fine on stock bolts re-tourqed to 72lbs for years on a 140,000+ mile stock gasket, but ONE detonation event at about 20psi was it for the stock gasket. (Sure, I did not mean to boost that high, and it was on the 550/lexus combo with a bolt on T-4 based turbo, but at less than 20 psi it ran great, made 420hp at the wheels at 18psi and was a trouble free engine for the most part.)

The reality is your going to have an overboost from time to time, and it only takes a moment to exceed what the stock gasket can handle. (Same goes for stock pistons, but that's another story, they tend to melt/crack at the ring lands when you run them hard but that's another subject.)

If you can control your boost pressure, keep it from detonating and a host of other things, your stock gasket will most likely be fine.

All boils down to how much time and money do you want to spend on this car? LOL

I reccomend studs always as they are not much more money, and you can use them either way, no matter what mods you end up with in the future.

Same goes for gaskets. IF you replace a gasket and don't put in a metal one, I consider that throwing good money after bad. Your going to replace that gasket again, it's just a matter of time/boost/gas. Simple as that.

 

[hock2k5]

I'd rather not replace the headgasket again already...it was done just 3,000 miles ago, along with the bolts. Think it would be good to just swap out the oem bolts for the arps, just doing a direct swap of the bolts only?

I dont mind doing a headgasket, i've done them on hondas, but i didnt have to take the car to get the head or block machined either.

 

[abustiffy]

I'd rather not replace the headgasket again already...it was done just 3,000 miles ago, along with the bolts. Think it would be good to just swap out the oem bolts for the arps, just doing a direct swap of the bolts only?

I dont mind doing a headgasket, i've done them on hondas, but i didnt have to take the car to get the head or block machined either.

Ive done the bolts without gasket in the past. Do them 1 by 1 in factory sequence.

 

[Adjuster]

In your case, I'd just use what you have, tourqe the stock/existing bolts to 72lbs and call it good for now.

Or just leave it alone, and deal with it when your head gasket blows, if it ever does. (It might not go you know.)

If your running stock levels of boost, stock CT and some other normal mods like a DP and catback etc, I don't see any reason why a stock gasket would not be fine with 72lbs of tourqe on the stock bolts. (Heck, up to 15psi, it would most likely be fine, but every car is different, and there are no absolutes.)

When I re-tourqed my stock gasket, I did it this way.

One bolt at a time, following the TSRM pattern, from the middle to the outside, in X's I gently backed off each bolt about a 1/4 turn if it was tight, and then tourqed it. (I don't remember the tourqe figures now, but I do remember I ended up at 72lbs, and it took 3 passes.) I think it was about 55lbs, but it has been 11 years now.

So, you do the first pass, get them all to 55lbs, then raise tourqe to 65 and go again, and then 75 and be done with it.

The key is you want the tourqe wrench/nut/bolt to be moving when you take the tourqe reading/click. Otherwise your just reading the friction on the fastener.

Ok, so you only back off the bolts if they are tighter than your first tourqe goal too. On your next passes, you know your going tighter, so there is no reason to back them off anymore.

I found on my engine that a few of the exhaust side stock bolts were quite loose. I did not have a blown head gasket, and only decided to re-tourqe after reading about it on a fourm..

Reg Reimer had some stock bolts tested, and that's where the 75lb max tourqe reccomendation came from years ago. I figured 72 was totally safe, even on my used bolts. (At some point the metal goes plastic, and your just stretching the bolt, not adding any more clamping force to the head/gasket.)

Good luck.

 

[hock2k5]

Yeah, I may just double check the tourqe.

I would eventually like to up the boost down the road, after i do injecters and sometype of fuel management and a few other things.

the jdm engine came with the cylinder pressure test and everything looks good and even.

 

[americanjebus]

I have been running oem hg on oem head bolts just under fuel cut for over a year, and i rip on it. Main thing is make sure you car is TIP TOP, Im going into this next year with the oem hg but arp's and am going to go well past the fc mark, the main thing that keeps me from worrying to much about my hg is that i check my compression and use a block tester often and am getting ALL of the necessary mods such as fuel supply and tuning to make sure i dont detonate the crap out of the HG.

If you do the instal right, get it smooth and clean, torqued down past 75, and make sure you run enough fuel for the amount of boost you run, your set, just dont go hitting 22psi on a bigger turbo. (heh i wrote this before seeing adjusters post)

 

[staticpat]

18psi on retorqued headbolts on stock HG has worked for me so far. As mentioned anything is possible with a good tune. Detonate and it won't last.

 

[gtsfirefighter]

I've been seeing these rebuilt CT 26 turbos on ebay with 57 and 60 trim. They say just bolt on and go. Can stock applications handle these? Just how much more boost are they kicking out than a stock CT 26?

 

[staticpat]

I don't know specifically but my upgraded ct-26 is in its efficiency between 16-18psi. They will push more air at lower boost levels, but you really want to have them above 12psi to feel their power.

Of course you will need to get around fuel cut, so it probably wouldn't be worth it in a stock application. Bolting on and go will work, but there are probably better things to spend your money on.

 

[starscream5000]

I've been seeing these rebuilt CT 26 turbos on ebay with 57 and 60 trim. They say just bolt on and go. Can stock applications handle these? Just how much more boost are they kicking out than a stock CT 26?

First of all do your basic maintenance and upkeep before worrying about that. After you have that done, then you try it out .