403rwhp on just 9psi?

buddyf87 · Dec 16, 2007

I have a friend with an '03 GT that just put down 403rwhp with just a 9lb vortech sq trim, and the dyno guy said he would be looking at about 425 if he got his fuel pump to stop leaking pressure. His only other mods are longtubes, gears, CAI, suspension, and fuel pump for the blower. How is it that the 4.6's can make this kind of power with just 9psi and we would be looking at like ~325rwhp or so? When he got it he was talking about how he was looking for between 400 and 450hp cause the guy he bought it from on ebay had a dyno sheet boasting these #s, and all my friends were telling him he was gonna be really disappointed cause the guy obviously had other mods to put down that much on just 9psi. I'm just really confused how he gained that much power on low boost and no other mods to speak of.

parchisi · Dec 17, 2007

A friend of mine had an '04, same blower, same boost, and was putting down 365 to the wheels. Interesting that there was such a difference. Anyways, those modular engines respond very well to forced induction. The downside is that its hard to get big numbers naturally aspirated. Remember, these engines are a lot newer with a lot of development put into them. If Ford had had stuck with the SBF, as Chevy did with the SBC, then we'd probably be seeing big numbers like that too from stock 5.0's.

urban96 · Dec 17, 2007

the 4.6's LOVE boost

BlownFiveLiter · Dec 17, 2007

urban96 said:
the 4.6's LOVE boost

Says the man with the KB 02 GT...

urban96 · Dec 17, 2007

StangGT1995 said:
Says the man with the KB 02 GT...

millhouse · Dec 17, 2007

urban96 said:
the 4.6's LOVE boost

And properly setup 5.0's love boost just the same.

final5-0 · Dec 17, 2007

Using a value of PSI is a poor way to judge possibilities of performance IMHO

Allow me to give two extreme applications for examples

1) OEM Stang with no mods and a basic blower kit

2) Same basic blower kit on a h/c/i/ Stang with all supporting mods

See how the psi is gonna be ........

greater on #1
but
less on #2

Boost values are nothing but a measurement of restriction to the flow

Just something to think about ... you might say

Grady

ProKiller · Dec 17, 2007

i'm not too suprised. little bit higher than i would have expected, but even so, the 4.6s, like said before, love boost in the high rpms. and again like grady said, you can run 12# on a stock 5.0, then add a good H/C/I and with same pulley only see 9#.

final5-0 · Dec 17, 2007

ProKiller said:
i'm not too suprised. little bit higher than i would have expected, but even so, the 4.6s, like said before, love boost in the high rpms. and again like grady said, you can run 12# on a stock 5.0, then add a good H/C/I and with same pulley only see 9#.

So then ... Just to be certain everybody is on the same page

Using Ryan's above example

Did the ole boy that lost psi gain hp

This is a test ... and ... Only a test

Grady

buddyf87 · Dec 17, 2007

makes sense, thanks guys. i didnt realize those engines had such potential with boost. i now have a new found respect for boosted mods.

and thanks for that explanation grady, i had never thought of boost that way before. good stuff, good stuff.

final5-0 · Dec 17, 2007

buddyf87 said:
and thanks for that explanation grady, i had never thought of boost that way before. good stuff, good stuff.

O Gosh ... O Gee Wiz

I just love it

When I caused someone to think outside of their box :Word:

Grady

cbarr300 · Dec 18, 2007

It's just like blowing through a straw. If you blow through a small straw and have a boost gauge in you mouth...you'll have higher boost than if you blew through a huge straw....but you know that more air flowed through the bigger straw than the smaller straw.

I'd like to see his torque curve

final5-0 · Dec 18, 2007

final5-0 said:
So then ... Just to be certain everybody is on the same page

Using Ryan's above example

Did the ole boy that lost psi gain hp

This is a test ... and ... Only a test

Grady

Well

I've seen no answer

It would seem to me

Nobody knows the answer

Everybody thinks the answer is obvious

Some of the bodys are afraid to answer for fear of being wrong
which
On this site ... that kind of thinking is ... for the most part ... unfounded

Hello ... I'm tapping on the screen here ...

Did that guy loose power when he lost 25% of his boost ???

Come On ... All you wanna be grasshoppers

Here is the perfect opportunity to ... Show Your Wisdom

Grady

FlyBy763 · Dec 18, 2007

no he did not lose power

sn-95matt5-0 · Dec 18, 2007

no he didn't loose any power. his is making more power

he is making more of a gain because of his more efficient setup is putting the boost to better use than the lower flowing setup.

cbarr300 · Dec 18, 2007

he's obviously making more power. I sorta kinda tried to answer that with my straw scenario. He puts better flowing (than stock) parts on and that's like moving to a bigger straw. More air flows through it without as much backpressure. Even though it registers as less backpressure.... "less boost" .... it flows more air. Blow through a big one and a small one and see which one makes you run out of breath first

An engine is basically an airpump...flow more air and it will make more power.

say you have an inefficient combo....and you spin a supercharger 50000 rpm on it and it's making 11psi. Get an engine that is efficient and flows well....and put that same 50000 rpm blower on there.....and it'll make say 8-9 psi. This is because the engine can pass that air through rather than just let it build up in the intake. That blower is still flowing the SAME AMOUNT OF AIR regardless of "boost" readings. A blower turning 50,000 rpm (given the same internals are used)...is gonna flow the same amount regardless of what's behind it.

It's all about the cfm, folks

cbarr300 · Dec 18, 2007

no dirty jokes fellas (Jt, Wes) haha

final5-0 · Dec 18, 2007

Ha Ha

I knew if I pressed you enough

You guys would start to think out loud a bit

Grady

cbarr300 · Dec 18, 2007

I just think that everyone should know that boost numbers don't always tell the tale...as with dyno numbers. You have no idea how many times I've had to use the straw scenario to explain stuff to people haha.

Stanger007 · Dec 18, 2007

Boost junkie

cbarr300 said:
no dirty jokes fellas (Jt, Wes) haha

I don't know what I could possibly take a jab at?

The supercharger stuff is amazing. You see guys with stock 5.0 engines and S-trims putting down 350hp at the wheels and running 12s easy. Who cares that you have to spin the engine a little with a centri blower... who races at 2500rpm? If anything, you don't want a big hit of power down low unless you are seeing who can make the most noise and go nowhere!

Here's a secret, on your higher output setups there is a little thing called a bypass valve. It doesn't let you build boost until the manifold vacuum drops (pedal goes down). This gives you power when you want it and great gas mileage/drivability when you don't want to haul butt.

My stock longblock was already in boost before I even started moving at the track.

Now go find the guys that have h/c/i AND blowers on their 5.0s, they are putting down 400-550rwhp depending on the tune and cam choice and other boltons.

This stuff is nuts... boost is easy to put on and addictive, you just can't get greedy with the tune or you will lose a headgasket or lift the heads... ask me how I know.

Wes

P.S. If it isn't fast enough buy another pulley...

403rwhp on just 9psi?

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