I have always understood a 4# lower on a stock bottom end with all the bolt ons was "safe" with the right tune. But i have noticed more "stock blocks" with 6# lowers running around. So has been running a 6# and what #s are you putting down, what boost levels are you seeing, details etc......

And who has blown a motor running a 6# and the details there!

The reason i'm asking is because i'm running:
stock 04 block
4lb lower
ported eaton
CAI
sbtb
C&L plenum
dynatech LTs/cats/mids to true duels out
and all the normal bolt-ons
I'm seeing 13psi of boost WOT and i understand more power with less boost is great but i'm wondering if a 6# would be a "safe" upgrade for me? She is a DD and no back-ups!

Correct me if i'm wrong but i think what kills these motors are detonation, to much boost, and just to much HP.
So if i get a great tune and rule out detonation and my boost level is "safe" (whatever that is, trying to find out), then my limiting factor would be hp and it seems that 450 rwhp is again a "safe" limit. I have done a search but it's hard to put in 6# when the d@mn thing requires 3 letters so i'd appreciate your inputs!!

 

Having said that, I would stay with the 4 lb lower.

 

exactly, until you have a reserve fund for a new motor, or get a beater car for a backup. my truck was my DD and it went, and I was stuck without the truck and had to bum rides for a while.

 

So overall a 6# no matter how well tuned is still questionable? Thanks guys

 

Since you have a ported blower a 6# er and a "safe" tune is doable. but instead of taking it to the edge why not run a 4#er and a hotter tune?

I've got a 4# lower and pass 6# guys on the top end of the 1/4.
(Because of the awsome REM dyno tune)

Rich

 

It's my daily driver, no backup. Power and mods in sig. She has 85k miles on her now, 50k on current setup. I run the chit out it. No trouble motor or tranny wise. It's all in the tune (I'm on the same plugs for those 50k miles) (or maybe luck of the draw with a solid motor from the plant)

The only thing I can't attest to is the hp limit. I'm sure some people out there have run over 450 hp on a stock block fine with a good tune.

BD

 

the 6er is safe with headers, I even got one on my 82K mile truck with stock exhaust. however I have the weakest tune a lightning has ever seen. Full exhaust and more boost comming soon.

JimIII@JDM

 

I also have just bought a used JLP 6#er and I plan on putting it on as soon as James with RWTD get me my new tunes. The guy I bought it from ran it for over 30,000 miles with stock plugs and had no problems at all.
jeff

 

I have a 6# with Apten ported Eaton.

I'm adding Bassani headers and Hi-Flow's in a few weeks... Right now they are sitting on the shelf.

 

Yep.........but remember you have a ported blower, which is extra boost... DON'T DO IT. Danger Danger . I am running a #6 with with the stock blower...

 

Isn't boost a measure of backpressure?

With headers and hi-flow there is less backpressure, that is why I'm adding it, to free up the exhaust and reduce backpressure.

I think your safer running a 6# with hiflow and headers than a regular 4# with stock exhaust.

 

Thats what i keep saying and that is why i posted this confused? I know i am!! hell i figured a ported blower was safer than a nonported blower!

So if boost is the vilian what is a "safe" boost level on a stock block from an autometer gauge?? 15psi 13psi? Maybe the correct question is whats a deadly psi rating 15-16-17psi??

 

I am going to a 2# upper with my 4# lower. I have a ported eaton, full exhaust, and a great safe tune from psp. Am I in danger of venting the block?

 

Yes but remember he has a ported blower which is roughly 2 lbs of extra boost... With long tubes and exhaust I lost approx. 1 lbs of boost, so he could be running if he adds a #6 at least 7 lbs of boost over stock or a total of 15 lbs of boost........High Cylinder pressuse causes problems... I could be wrong, but that my feelings...

PEacE.........................
Jim

 

A good friend of mine has been running a 6 lb. lower, with a CAI and a Magnaflow muffler (no cat-back) for months now. Truck made 405 and 517 on a Mustang dyno with a "safe" tune from Sam @ Coastal.

Sam has tuned many of these trucks and he stands by this:

Prevent detonation and keep the RWHP at or below 450 and a stock block is safe.

From what I have read here, the Apten port is so effective in part because more of the intercooler surface is used, so the air charge is cooler. The 6 lb. spins the blower faster, which in turn generates more heat, but the Apten port should help offset that additional heat.

I say port the blower, run the 6 lb., get a "good" tune, and have fun...