Tst=blown Head Gasket

[Fred Swanson]

Hook a pressure gauge to your pyro port on the manifold, and see where it goes in relation to your boost.

I use my e-brake gauge with copper line so I can leave my 2 boost gauges in tact.

 

[hammersley]

Also I've been told ---

that you want to watch your boost very carefully (keep under 20 lbs) till you get the engine warm! Otherwise you're headed for trouble.....

 

[PGoble]

I've been running twins, DD3's, and TST for about three months now, blow-off valves are set at 60psi and I haven't had any problems with the head gasket. I'm still running the stock head gasket and studs. I think Piers is up to 65 or 70 psi with his stock head gasket.



Peter

 

[Yo Hoot]

If there is a weak point in the sealing of the headgasket... be it a less than perfect gasket, head/block machine surface or an assy anomaly, you can be sure a power enhancer will bring it out.



My Dmax blew a headgasket on a 90hp Juiec box on top of lp. I know a ton of guys running way more than I did with no head gasket issues.



I think it's an isolated case.

 

[Vaughn MacKenzie]

Fred, Evan Beck was telling me he did some exhaust manifold pressure readings and said the stock turbo tracks pretty close to 1:1, that is, drive pressure and boost pressure are close to the same, as long as the wastegate is operating normally or boost isn't forced beyond stock levels.



Clamp the wastegate shut and force the turbo to higher boost levels, the restrictiveness of the ehxaust housing comes into play (remember it's a wimpy 9-10cm affair) and drive pressures go up exponentially. I think Evan said at about 35-40 lbs boost the drive pressure is about double. . . 75-80psi. You can only imagine what the drive pressure is at 48lbs boost



Then you think about the compressor side, which certainly is losing efficiency by 40psi, the air being pumped out is getting mighty hot. There has to be a point of diminishing returns, and even if you have enough fuel to run it to 48psi, you're probably well past that point, and would be better off wastegating it to 38psi.



There's a lot I don't know about twins, I don't know how drive pressures compare there, but on the intake side that 60psi of air being fed to the intake is certainly whole bunches cooler than the air from that stocker spinning its guts out making 48psi



Vaughn

 

[Tomeygun]

I've been running twins, DD3's, and TST for about three months now, blow-off valves are set at 60psi and I haven't had any problems with the head gasket. I'm still running the stock head gasket and studs. I think Piers is up to 65 or 70 psi with his stock head gasket.



Peter

sorry to hijack the thread,

But, Peter, thats some serious Hp mods... What are putting to the rear wheels with all that fuel and air??

 

[robertyoke]

also, there is a big difference in 45 psi and egt's at 1800 deg and 45psi and egt's at 1200 deg. way more stress on a over heated head gasket.

 

[BCarmicle]

Clamp the wastegate shut and force the turbo to higher boost levels, the restrictiveness of the ehxaust housing comes into play (remember it's a wimpy 9-10cm affair) and drive pressures go up exponentially. I think Evan said at about 35-40 lbs boost the drive pressure is about double. . . 75-80psi. You can only imagine what the drive pressure is at 48lbs boost





Is the 1:2 turbo to drive pressure ratio the same at the higher boost? If so, hitting 80lbs. of boost means that drive pressure would 160psi. What is the limit of drive pressure for these engines?



Brandon

 

[PGoble]

sorry to hijack the thread,

But, Peter, thats some serious Hp mods... What are putting to the rear wheels with all that fuel and air??

Tomeygun,



Last Dyno was 556 hp/1125 tq at around 55psi.



Peter

 

[WPeschel]

48 lbs of boost definitely pushing it just fire ring it this time probably hold. Best is o ring of course that involves downtime and $$$ If your gonna be pushing your luck running those kind of boost levels you should be retorqing cylinder head occassionly that will help gasket last longer

Kyle what is fire ring?? How much does it cost??

 

[Tomeygun]

Kyle what is fire ring?? How much does it cost??

Thats exactly what I was going to ask... so???

 

[Vaughn MacKenzie]

Is the 1:2 turbo to drive pressure ratio the same at the higher boost? If so, hitting 80lbs. of boost means that drive pressure would 160psi. What is the limit of drive pressure for these engines?



Brandon

No, it goes up exponentially, so chances are at 80lbs boost you're drive pressure is maybe 300 psi or more



Please don't tell me you run your stock turbo that high

 

[BCarmicle]

No, it goes up exponentially, so chances are at 80lbs boost you're drive pressure is maybe 300 psi or more



Please don't tell me you run your stock turbo that high

Nope, doubt the little stocker could take that. The only time I ran the stock turbo was for about the first 3K when the truck was totally stock.



I'm running twins that make the 80lbs. Well they did a few times at least. Now I'm not going to let them get over 65lbs.



So does anybody know at what psi is too high for drive pressures?



Brandon