Jump to content
TEAM SHELBY FORUM

HP w/o supercharger


Recommended Posts

Anyone know what the HP is w/o the supercharger on our cars.Seems like im driving around mostly in 3rd, and the SC will kick in when i hit the throttle--no complaint,its pelnty resposnive, so i was curious what the naturally aspirated HP is??Im guessing its 400,based on how my wfies vette feels,which is 400hp.

Edited by Torched10
Link to comment
Share on other sites

I've wondered the same thing.

 

And since I spend so much time not under boost, it's nice to have the 4.10 gears to give that extra seat of the pants. Now I love the car with or w/o the boost!

 

im wondering if i could "deduce" it from looking at a dyno chart.To me it seems that the SC kicks in around 3,000 in 1-3 gears.So maybe whatever hp gain there is from there on up thru the gears on a dyno chart would seem to be SC related--but what do i know, im an elec guy

Link to comment
Share on other sites

im wondering if i could "deduce" it from looking at a dyno chart.To me it seems that the SC kicks in around 3,000 in 1-3 gears.So maybe whatever hp gain there is from there on up thru the gears on a dyno chart would seem to be SC related--but what do i know, im an elec guy

 

 

On the flip side I think our sans-SC power numbers would not show an accurate picture of what the motor produces compared to say the new 5.0. Our motor is built knowing there will be a SC in the missionary position and therefore has a low compression ratio. But something like the new 5.0 has a very high compression ratio and that's why it will not see tremendous gains when adding a SC; and if tremendous gains are achieved it will be short-lived.

Link to comment
Share on other sites

typically double atmosphere (14.7psi) doubles the power on an N/A engine. Of course the parasitic drag from the blower will suck some power out of boost, plus compression tends to be a little lower on supercharged cars.

 

So if its rated at 540hp@9psi, I would say 540*.612=330hp, minus a bit for the drag of the blower, probably about 30hp at higher RPM.

 

But if the same engine had more compression, better intake, exhaust, more optimized cam timing etc I'm sure these would be over 400hp.

Link to comment
Share on other sites

typically double atmosphere (14.7psi) doubles the power on an N/A engine. Of course the parasitic drag from the blower will suck some power out of boost, plus compression tends to be a little lower on supercharged cars.

 

So if its rated at 540hp@9psi, I would say 540*.612=330hp, minus a bit for the drag of the blower, probably about 30hp at higher RPM.

 

But if the same engine had more compression, better intake, exhaust, more optimized cam timing etc I'm sure these would be over 400hp.

 

 

That sounds about right as I'm expecting to be around 600-620 rwhp once I get the 67mm TB and 2.6" pulley installed, as that will put me right at 15 psi.

Link to comment
Share on other sites

Anyone know what the HP is w/o the supercharger on our cars.Seems like im driving around mostly in 3rd, and the SC will kick in when i hit the throttle--no complaint,its pelnty resposnive, so i was curious what the naturally aspirated HP is??Im guessing its 400,based on how my wfies vette feels,which is 400hp.

 

 

I was wondering the same thing tonight while I was driving around. Great question.

 

Compared to my former 300HP non-supercharged car..I would definitely say there's more TQ - and a good bit more HP. That's just from seat of the pants feel.

Link to comment
Share on other sites

Interesting question - the new 5.0 might have more HP than the 5.4 w/o the S/C, but not as much torque.

 

Keep in mind the 5.0 runs 11 to 1 compression vs the 5.4's 8.4 to 1. The 5.4 also has a longer stroke and smaller bore (basically a truck motor). The 5.0 is designed to rev higher. I wouldn't be suprized if a 5.4 was making only around 350-370 HP without the supercharger due to the lower compression and would make it's max hp at a much lower rpm than the 5.0.

Edited by Cdvision
Link to comment
Share on other sites

Keep in mind the 5.0 runs 11 to 1 compression vs the 5.4's 8.9 to 1. The 5.4 also has a longer stroke and smaller bore (basically a truck motor). The 5.0 is designed to rev higher. I wouldn't be suprized if a 5.4 was making only around 350-370 HP without the supercharger due to the lower compression and would make it's max hp at a much lower rpm than the 5.0.

 

 

Our 5.4L runs 8.4:1 compression, not 8.9:1. Just letting you know...

Link to comment
Share on other sites

Our 5.4L runs 8.4:1 compression, not 8.9:1. Just letting you know...

OK I had a brain fart, too many numbers rattling around in my brain,post edited. That would mean even less power without boost.

Edited by Cdvision
Link to comment
Share on other sites

Several years ago I did a 67 fastback for a customer who refused any aftermarket hood or to modify the the stock hood in any way, so we removed the supercharger and installed a Sullivan upper intake. It made 345 RWHP stock through the 6060 and 03-04 Cobra IRS. Less than 30% humidity and 100 degree heat. Don't remember the torque. Later we installed a custom turbo set up with intercooler and no other mods and it made 665 RWHP.

 

Alex

Link to comment
Share on other sites

I dont know but I bet a new stock 2011 5.0 GT has enough hp to beat a stock 07-09 GT500

 

412hp for GT

500 for GT500

 

But GT500 weighs at least 300 pounds more

 

Id love to race one with 373s just to see how close or not close it is

 

 

You might as well say 07-11, because they all make roughly the same HP assuming a cold air intake is in place.

Link to comment
Share on other sites

Every 1/2 point of compression is worth roughly 15 horsepower. However, you also must consider the cams used have been profiled to provide as little overlap as possible so as to maximize the use of the boost (at least, I would presume such...)

 

You can take an educated guess, but it will still be a guess.

Link to comment
Share on other sites

I too was wondering about this cars hp under non s/c conditions. When I drive around town, I don't get much boost. However, The n/a power of this car is still very impressive. I have about 3500 miles on my 2010 now and have really developed a great appreciation for the acceleration of this car without boost. Changing lanes, making a yellow light, and hitting turns are such effortless tasks to perform while not under boost. The more I drive this car, the more i grow to love the "complete driving experience"

Link to comment
Share on other sites

I too was wondering about this cars hp under non s/c conditions. When I drive around town, I don't get much boost. However, The n/a power of this car is still very impressive. I have about 3500 miles on my 2010 now and have really developed a great appreciation for the acceleration of this car without boost. Changing lanes, making a yellow light, and hitting turns are such effortless tasks to perform while not under boost. The more I drive this car, the more i grow to love the "complete driving experience"

 

 

In general, a supercharger is always working, forcing some amount of air in. The boost guage measures the manifold pressure. On a non-boosted car, manifold pressure is always negative as the engine is sucking air in. If the stock boost guage could go negative, you would see it move even around town as your throttle/rpm changed. Not quite sure how it is tuned, but even at low RPM, the 5.4L with supercharger probably has much less negative manifold pressure than a non-supercharged engine would.

 

If you take off (or break) a supercharger belt, the manifold vacuum actually spins up the supercharger by sucking air through it. If it isn't being driven by the the engine the supercharger roters restrict airflow to the engine. From experience in a different supercharged toy, I'd guess you lose 1/2 the horse power of the base engine that way. Starting a supercharged car without a belt is extremely difficult, particularly at altitude.

 

I am curious how Ford implements the initial 5 mile/50 start/stop cycle "no supercharger" startup, is there clutch on the drive mechanism or air bypass somewhere in the system? I need to pickup a shop manual.....

(Edit: just remembered the GT500 is a drive by wire sort of toy, so they could just back off the throttle when the boost gets above a certain negative, zero, or positive threshold?)

Edited by rhlgt500
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...
...