What's my boost safety/danger zone?

[CajunKenny]

Hey guys. I've done a little reading and found conflicting opinions and information.

Here's my mods:

Bosch BOV
K&N
Flex-A-Lite Electric Fans
3" Exhaust from the turbo back
Shimmed Wastegate hitting around 9psi
Everything Else Stock including the Headgasket. 116k on the car.

Here's my questions:

If I were to purchase a manual boost controller what boost level(s) can I "SAFELY" run with my current HG ~vs~ a MHG?

What's the success rate of installing a MHG without head and block work considering neither are warped. With ARP Head Studs of course.

Thanks for your thoughts. :icon_bigg

 

[eman2289]

to your first question, none. The hg will go, so you are better off just doing the mhg now. People have done a Mhg with no machining, but its risky. You could also do a non metal by and torque it correctly. I always go by the motto "do it right the first time". So if I were you, I would do the machining, mhg, and arps.

 

[MKIIINA]

its not going to be much higher than you are currently really because fuel cut will start becoming an issue between 11-13psi (normally) get the hg done as they are notorious. past that will be fc.

 

[CajunKenny]

I suppose I could have the head done; but, is it possible to adequately prep the block while it's in the car?

 

[GrimJack]

Possible, yes. Likely, no.

Trying to prep the block without the ability to get it cleaned properly afterwards is more than likely going to end up with iron dust from the lapping process in your bearings.

Your bearings will not appreciate this.

So, you need to decide whether you're happy with the level of power you have now (in which case, get a new stock gasket from Toyota, pull the head, get it surfaced, clean the block, bolt it all together and regularly sacrifice virgins to your favorite automotive diety) or you want to be able to increase the power from here, in which case you should likely pull the engine and do all the work to switch to a MHG.

Or just buy another engine and work on it until this one dies.

 

[dugums]

So, you need to decide whether you're happy with the level of power you have now (in which case, get a new stock gasket from Toyota, pull the head, get it surfaced, clean the block, bolt it all together and regularly sacrifice virgins to your favorite automotive diety) or you want to be able to increase the power from here, in which case you should likely pull the engine and do all the work to switch to a MHG.

Or just buy another engine and work on it until this one dies.

I did mine by machining the head and using a stock gasket. I have regretted that decision for many reasons. My engine runs strong, but just as grimjack said, there is a (possibly irrational) lack of faith in the composite headgasket (even when properly torqued). Just for the additional peace of mind in the future, I would strongly suggest considering doing the work to do the MHG.

Now, the most compelling reason I have found to do the MHG is that it might actually save a little time. About two months after I was done with my HG job, I helped a friend do his MHG.

Removing the engine was not even close to as hard or time-consuming as disassembly of engine and components in the car. The time saved by working on the engine on the stand was significant. Everything is nicer - you just send the block to the machine shop - no need to worry about cleaning gasket crap off, worrying about whether you got everything clean, etc...

I think since I never had done it, I was afraid of removing the engine and trans. There is no need, if you can follow directions, it is much easier than the in-car method. The benefits are huge too - namely the ability to run a metal gasket, replace bearings, re-ring, check bottom-end clearances, etc.

Please, Please, PLEASE consider doing it the right way. It has the benefit of being easier and RIGHT.

 

[CajunKenny]

Thanks for your thoughts guys. I do appreciate it. I'll take your advice and keep my current setup as is and concentrate on building up a second one with a MHG.

I was just toying with the idea of getting a little more 'umph' out of my current setup. You know how it is! I want MORE power and I want it NOW!!!!! :evil2:

Thanks again...

 

[a_sesshoumaru]

is not just peace of mind, i blew two oem headgaskets on 12 psi of boost torqued down to 82lb/ft, luckly i do my repairs, you need a MHG to raise your boost past 9psi, you might put the MHG with out getting the block prepared but you have to make sure messuring it, even if it has 1 thousand of warpage would be risky but still ok, beyond that it has to be prepared, make sure the head is completly ok; no warpage at all.

 

[Rennat]

i could defintaley see a good intercooler and piping helping you, i dont know if it'll make more "power" but lets face it... the OEM lines arent exactly pretty... and that OEM bov sucks so much balls its gross...

and if you really want more power, lex afm and a set of 550's, then crank up the boost and watch the HG blow! then you'll have an excuse to rebuild the motor!!!

 

[Rennat]

is not just peace of mind, i blew two oem headgaskets on 12 psi of boost torqued down to 82lb/ft, luckly i do my repairs, you need a MHG to raise your boost past 9psi, you might put the MHG with out getting the block prepared but you have to make sure messuring it, even if it has 1 thousand of warpage would be risky but still ok, beyond that it has to be prepared, make sure the head is completly ok; no warpage at all.

please let me know when you can find an aluminum head with less than .001 of warpage after blowing the gasket...

did you use arp head studs or just oem bolts??

 

[CajunKenny]

that OEM bov sucks so much balls its gross...

Tell me how you really feel about the OEM BOV! :biglaugh:

I forgot to menion that I upgraded to the Bosch BOV. I edited my original post. :icon_bigg

 

[GrimJack]

is not just peace of mind, i blew two oem headgaskets on 12 psi of boost torqued down to 82lb/ft, luckly i do my repairs, you need a MHG to raise your boost past 9psi, you might put the MHG with out getting the block prepared but you have to make sure messuring it, even if it has 1 thousand of warpage would be risky but still ok, beyond that it has to be prepared, make sure the head is completly ok; no warpage at all.

I suspect there was something else happening here.

I've run a lot more boost than that on a stock HG without any problems. Now if you start to run into detonation, that gasket won't last long - but then again, neither will your stock pistons. Last engine I ran with a stock HG, by the time I'd managed to blow the HG, I'd also shattered 3 pistons.

 

[IwantMKIII]

What's the success rate of installing a MHG without head and block work considering neither are warped.

This comment just can't lead to good things for you or your car.....

you know its not warped how?? And please, don't say something along the lines of "it looks fine"

 

[CajunKenny]

you know its not warped how?? And please, don't say something along the lines of "it looks fine"

I know that there are some...less than informed folks around. (was I politically correct enough there? :sarcasm No, I would take the head to a machine shop and have a friend of mine who is a machinist and an MKIII owner help me inspect the block.

The last thing I want is trouble with my 7MGTE. I get enough of that just from the nature of that beast!! :biglaugh:

 

[HommerSimpson]

strait edge is about 80 bucks.. You can put a light coat of paint on block and take strait edge at a slight angle and scrape back and forth.. were ever paint stays.. its low.. were ever it comes off the quickest is high...

 

[IJ.]

Keep it out of detonation and there's NO REASON for a composite HG to "blow" as long as everything is done right.

I used to run my Twin T04 Toyota V8 at 30 Psi with no IC back in the day with Composite HG's and no failures........

 

[CajunKenny]

So let me ask this: What's the feeling about running ARP Head Studs on a new OEM Head Gasket? Am I still asking for trouble above 9 psi?

 

[IJ.]

Kenny: If you keep it out of detonation it shouldn't be an issue assuming everything is flat/true and the HG is tourqed correctly. (including a retorque)

 

[Dan_Gyoba]

I'm running ARP studs on an OEM gasket. Re-torqued studs to 85 lbs, as per ARP spec.

I don't expect to have problems with this, and I am planning on going over 9 lbs.

One thing that I am NOT planning on doing is playing with lean conditions. The factory mixture is pig rich, and there's some power to be had by leaning it out a little, however, I'd rather leave a little power on the table, so to speak, in exchange for a little more safety margin. So if I'm burning a bit more fuel and making a bit less power, so be it.

 

[GrimJack]

I'm running ARP studs on an OEM gasket. Re-torqued studs to 85 lbs, as per ARP spec.

I don't expect to have problems with this, and I am planning on going over 9 lbs.

One thing that I am NOT planning on doing is playing with lean conditions. The factory mixture is pig rich, and there's some power to be had by leaning it out a little, however, I'd rather leave a little power on the table, so to speak, in exchange for a little more safety margin. So if I'm burning a bit more fuel and making a bit less power, so be it.

That's what I did with my last motor that had a stock HG.

I was slowly building another 7M with forged internals at the same time, so when I got that done and was ready to swap it in, I cranked up the boost a couple PSI every week until I blew up the stock HG.

It was actually pretty tough to blow - I was past 20psi on a 60-1 upgraded CT. Of course, it blew a bit more than just the gasket, too. I gave away the remains of that motor just last summer!