Engine/Transmission (1994 - 1998) Is high boost necessary for HP?

[Tom C]

Can you get say 400 to 500 HP without having your boost over say 30 Lbs?



Pro's - Con's ?



I'm trying to figure out how to get the power without having to replace my head gasket. Besides whats shown in my sig I'm looking at adding DDP3's , Snow #2 water/meth injection and Turbo (not sure which one though).



Tom

 

[WDimig]

your headgasket wont live long if you up the timing over 16. 5 deg. also the water meth isnt going to help, it will spike the combustion pressures too much, especially with added timing.



wes

 

[Missouri Mule]

You would need to increase airflow to the turbo (by uprading your stock air intake system).

 

[zstroken]

Ideally if you could get the motor breathing you could get some numbers with lower boost, but HP is pretty much directly related to cyclinder pressure. I ran 18 degrees for 6 months with zero head gasket issues. I have since advanced it more, but the head is oringed and studded. I woudl be cheaper to oring and stud than it would be to get the engine breathing free enough to make 450HP on 30 psi.

 

[Jim Fulmer]

Mine makes 600@40 psi on #2 only.



Jim

 

[PRattenbury]

But what is not said is what it took modification-wise to get that to happen. Would it have been cheaper to just o-ring and stud??? I would assume your head has been ported, you have an aftermarket camshaft, maybe intercooler... . Sure, it can be done, but at what cost?

 

[CSchafer]

I have to believe that with a good turbo and proper fueling that you can get 400 hp with out ever taking of the head. Both of my trucks get run to 38-40 psi and havent had any problems. Now 400hp at 30psi, your gonna get some serious headwork done in the flow department so it might as well be o-ringed then,or while your putting in a cam

 

[RustyJC]

It's not really boost that you need, it's mass airflow or supplemental oxygen. Ya gotta have enough oxygen to burn the fuel if ya wanna make the power - otherwise, additional fuel will just create smoke and heat. Boost is just one means to build mass airflow. Cams, head porting, NOx, more efficient turbos, larger intercoolers, etc. can provide more oxygen with lower boost pressures.



Rusty

 

[Tom C]

I guess it might be easier to replace the head studs then up the boost to 40-45 PSI ? Then deal with the gasket when and if it blows.



more pros - cons ?

 

[WadePatton]

I've been told by a reputable source that a stock head gasket and bolts will hold close to 70psi IF RETORQUED properly and frequently.



FWIW-- I don't run over 16 degrees.



There has to be a certain amount of boost in order to load the cylinders. With enough head, intake, and manifold work as well as a proper camshaft and charger--400-450 @ 30psi should be attainable, look at Jim. or maybe don't. :-laf



Or just retorque and throw a big charger on and dump the fuel to it... quick and dirty method.



edit: And I've run a little over 45psi for a LONG time in two trucks without popping a head gasket. POPPED the head gasket in the third truck because the timing was at 21-degrees. Assumed (and was told) it was 16: never assume.

 

[Timebomb]

I made 396hp/903ftlbs with 14cm stock 35, 3in straight pipe, on a 205k mile first gen. and that head dosnt flow what a 2nd gen head dose, all that stock crap and only 36psi and 1150deg. on the rollers @ 16deg of timing.

 

[Tom C]

Wade,



Its funny you mention re-torquing the head bolts. Last month I had the misfortune of the KDP falling out and breaking my gear case. As most know the cam has to be removed to replace the case. Which entails removing the rocker arm pedestal, etc. . While I had to torque the rocker arm pedestal while reinstalling them I did what the book said which was torque 89 lbs then turn an additional 90*. I found that the total torque after the 90* turn was 130 ft. lbs. . So I proceeded to re-torque all the head bolts to 130 lbs. . I found that all the bolts under the valve covers that I did not touch before checking (re-torquing) them turned about 1/2 to one full turn before getting them to the 130 lbs. The only bolts that did not budge were the ones not under the valve covers along the exhaust manifold side. My truck only has 73,000 miles so maybe the more miles you have the looser they will be until ---boom-- blown head gasket.



My last truck was a '95 model that when I sold it had about 180K miles. about two months after I sold it I learned the head gasket blew. I had never checked the head bolt torque. I wonder if I had re-torqued them if it would still have blown.



I wonder if there is any common mileage when these gaskets let go?



I had a BMW motorcycle that needed yearly valve adjustments. BMW required you re-torque the head prior to adjusting the valves. I wonder if this may be a thing to do with the cummins?