Option B. 100k is just right for a turbo on a stock LS. Throw in some good valve springs and a decent cam and have at it.

 

Thanks everyone! I am pretty well convinced of going option B now and leaning heavily toward the Trick performance stage 3 kit and upgrading to the precision 72/75 turbo. I think that will keep my happy long enough to build the 6.0 I want and do other important things like Better trans and all that junk


Anyone have that kit and love it or hate it and want to warn me away?

I would like to stay under 5k perferably closer to 4k

 

Am I too late to also say option B? Oh and film this **** too.

 

Also I am not going to touch the 4.8 as far as cam or anything goes. Because I want to focus the extra money into the 6.0 and when it is finished hopefully pull the 4.8 and jam it into my ranger.

 

You will at least need to upgrade the valve springs on the 4.8 to handle the boost. An upgraded cam in not necessary but will magnify gains from the turbo. Trick has very good turbo kits along with KB Racing. You wont hear much bad from anyone on either. Search the Forced Induction section to get an idea.....

 

I'm not reading any of the posts, including the OP.

The only thing that I have read is the title of the thread. My answer is as follows:


Yes.

 

AFAIK The boost will not put any additional strain on the valve springs. If he is keeping the stock cam and spinning the motor to the stock rev limit, there is no reason to change the springs. Stronger springs are needed with more aggressive cam lobes, or higher revving to avoid valve float and accommodate higher lifts.

 

If you have experience with this then I will believe you as I have none, but from what I have researched and know from a fluid flow perspective is the spring will be pushing against the boost pressure in order to close the valve. Now I have read of guys running 6-8psi with stock springs and not seeing issues but I have also heard of guys in the psi range experiencing valve float as well. If it were mine, I would do it for cheap insurance. If you bend a valve you will have to put the 6.0 money into the 4.8 or get that 6.0 built a lot faster than planed. Just my .02

 

Well here's my thought process. A 2" valve has an area of about 3.14 sq. in. (slightly less due to the stem). If you are running 15 psi of boost then that's about 45lbs of force trying to open the valve. LS1 seat pressure at 1.8" install height is 76lbs (not sure on trucks). So there's 30lbs pulling the valve closed. Plus the valve doesn't see the full 45 lbs of boost opening force unless the valve is fully closed and the pressure in the chamber is atmospheric. But if you take into account the chamber pressure doesn't go below the intake pressure for too long (only if exhaust creates a vacuum) and add the fact that the pressure in the chamber during combustion is extremely high, I am fairly certain that will keep it closed.

Most companies make bolt on supercharger kits that go up to 8.5 or so psi depending on the application and they are made to bolt on and last for a long time. I may be missing something though.

 

This is how I look at it not saying it is right and as I said I have no personal experience, this is just from what I have researched/read/learned over the years..........

First lets take into account that, at WOT, there is already pressure in the intake close to atmospheric of 14.7psi. Boost is measured relative to atmospheric pressure so, in your example above, that is 15psi + the atmospheric pressure in the manifold. This wont be 14.7 exactly due to many factors so lets assume it is 13.5psi. Then we have a total manifold pressure of 15 + 13.5 = 28.5psi multiplied by the 3.14 in^2 of the valve gives about 89.5 pounds. Now lets assume you are only running 8psi of boost. In this case, 8 + 13.5 = 21.5psi multiplied by 3.14 equals about 67.5 pounds which is still, in my opinion, close to the 76 pound seat pressure you mentioned in your post above. And lets not forget that 100k mile springs will not have the same seat pressure as brand new springs.

Also, the chamber pressure will most definitely go below the intake pressure during the intake stroke. When the piston goes down for the intake stroke it increases the cylinder volume while keeping the pressure the same. This means the psi in the chamber goes below the intake manifold pressure even on NA engines. If it didn't then air would not be forced from the intake into the cylinder. And yes, of course, once the valve is closed and combustion happens it will not open due to the combustion force but also due to there being no cam lobe force either.

But I digress, for $200 I am not going to measure my 100k mile springs force and determine if it could overcome the force of the boosted air.......I am just going to buy the springs and have peace of mind.

Someone that knows more than I do please correct me if I am wrong so we can all learn. Thanks!