Weak point of 4.6 3v?
04-27-2010, 04:14 PM
#1
1st Gear Member
Thread Starter
Join Date: Jun 2009
Location: Texas
Posts: 106
Weak point of 4.6 3v?
I know that the rods will be the first part to fail (most likely), but what is the actual limiting factor in a boosted engine? Boost, or HP?
I know that usually they both go hand in hand, but lets look at a hypothetical situation:
You get a Whipple 550 kit, and am running 465 to the wheels at 8 psi. Then you decide to invest in some blower cams and some long tubes. You are then running more horsepower (from the cams) but at a lower psi (from the headers). What is more dangerous for your engine? For that matter, you could put a larger pulley on after the cams to lower the boost. lets now say you are running the same 465rwhp, but are now down to 5.5psi (again hypothetically). Is that safer for your engine?
I figure that the answer is yes, 465rwhp at 5.5psi is safer for the engine than the same power at 8psi, just seems logical to me. But I keep hearing people saying that the stock rotating assembly is iffy at best past 500rwhp.
Could all of you knowledgeable people help explain this to me? Reason for asking is I am trying to figure out my FI plan and want to get good numbers, but do it safely (doesn't everyone?)
Thanks in advance for everyone's help!
I know that usually they both go hand in hand, but lets look at a hypothetical situation:
You get a Whipple 550 kit, and am running 465 to the wheels at 8 psi. Then you decide to invest in some blower cams and some long tubes. You are then running more horsepower (from the cams) but at a lower psi (from the headers). What is more dangerous for your engine? For that matter, you could put a larger pulley on after the cams to lower the boost. lets now say you are running the same 465rwhp, but are now down to 5.5psi (again hypothetically). Is that safer for your engine?
I figure that the answer is yes, 465rwhp at 5.5psi is safer for the engine than the same power at 8psi, just seems logical to me. But I keep hearing people saying that the stock rotating assembly is iffy at best past 500rwhp.
Could all of you knowledgeable people help explain this to me? Reason for asking is I am trying to figure out my FI plan and want to get good numbers, but do it safely (doesn't everyone?)
Thanks in advance for everyone's help!
04-27-2010, 06:47 PM
#3
5th Gear Member
Join Date: Oct 2009
Location: Oregon
Posts: 2,645
RPM and air/fuel plage a huge role in engines longevity as well. People with powerful cars, tend to run them harder (higher revs, more often) and thus engines suffer more.
Unless you are freeing up present power, you cannot get more horsepower without increasing cylinder pressure, which causes that crankshaft to kick over harder and faster, thus giving you more power output. Therefore, anything you do to increase power (different than free'ing power) will put the engine under greater strain.
Making a cylinder head flow better or putting in a cam with bigger lift/duration values still increases cylinder pressure. It has to, or else you're magically gaining more 'output' from the same amount of 'input'.
That is how I understand it anyways
.
Unless you are freeing up present power, you cannot get more horsepower without increasing cylinder pressure, which causes that crankshaft to kick over harder and faster, thus giving you more power output. Therefore, anything you do to increase power (different than free'ing power) will put the engine under greater strain.
Making a cylinder head flow better or putting in a cam with bigger lift/duration values still increases cylinder pressure. It has to, or else you're magically gaining more 'output' from the same amount of 'input'.
That is how I understand it anyways
.
Thread
Thread Starter
Forum
Replies
Last Post
jwog666
Pipes, Boost & Juice
11
12-27-2021 08:09 PM
MustangForums Editor
Mustang News, Concepts, Rumors & Discussion
0
09-25-2015 09:06 AM
