Using manual boost controller and re-torquing head bolts.

[Foxtrot]

Hey guys I recently purchased a very clean 1991 Supra turbo. I have owned Supras in the past but never a 7mgte. It was a grandpa driven car with very regular maint performed.

I am aware the headbolts are under torqued from the factory. However I also recall reading some people "re-torque" their stock bolts in sequence to 72ft lbs to provide better durability under boost. My question is, are the factory bolts torque to yield? Will they stretch and lose their strength if tightened?

Also, what is stock boost pressure? What is safest on a bone stock engine? Could I raise the boost to 8 and be safe?

I just recently replaced a lot of maint items such as plugs, CPS, ignitor, Alternator, TPS, knock sensor, transmission service (a340e) and brakes and tires.

Now that I have the car running healthy I would like any suggestions if possible about what I can do and what should be done. I payed a little over 5k for this beautiful Supra and I feel like I'm walking on egg shells everytime it goes into boost (Even in overdrive :cry: )

Thanks guys!

 

[Another MkIII]

the bolts are not TTY. Sometimes you can buy time with re-torquing the headbolts, sometimes you can't. I honestly wouldn't be surprised if retorquing causes some BHG's. I believe 8 PSI is stock for a manual, can't speak for an auto. On a stock (Not rebuilt) engine, I would keep it at 8-10 at most.

My opinion on what I would do, drive the car as is, and budget a rebuild for when the HG goes. Most people will say to re-torque, and that is really up to you.
-AM3

 

[Nick M]

You should make sure the bolts are tight, as 58lb/ft does not put it in the elastic region. And for the record, the bolt is supposed to stretch. That is the clamping force.

 

[jake8790]

My supra was the same as yours and one day I got home and coolant was overflowing and bubbling everywhere. I spent about $400 on an oem headgasket, arp headbolts, full hose set, gasket set, and having the head machined. I spent a few days cleaning everything and slowly put it back together. It's an easy and time consuming job. It's been running for 7 months now at 10 psi with no problems. I wouldn't bother retorquing, you are still using old bolts and an old headgasket. You can go the route I did or you can pull the motor, rebuild, have the block machined and install a metal headgasket. Much more durable, but much more expensive. It depends on how much you are willing to spend and how you plan to mod the car.

 

[Skeezix]

Re-torque it for now, and save up for a rebuild. No point in not doing it not, I did it on my car, gasket never went. Just sayin gives you more time to save for a better build.

 

[tyang82]

just try not to beat it and be prepared for BHG symptoms.

 

[Foxtrot]

Thanks guys! What should I torque them to? 72 lbs?