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How to get 350 hp or more on a 2007 mustang gt v8 automatic

Old 03-13-2019, 03:52 PM
  #21  
Dino Dino Bambino
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Originally Posted by 08'MustangDude View Post
Running without the belt you will get the most RWHP you can, because there is no belt installed to drive any
of the pulleys. If I build a 1/4 mile drag car, it will have an electric water pump, and manual
steering. The only belt you're going to see is the one driving the blower.
Well that's one point we CAN agree upon.

Originally Posted by 08'MustangDude View Post
For a daily driver, you settle with a UDP, that does not ADD BHP, it will simply add to your RWHP
with the reduced drag at the accessory pulleys.
OK. So if an engine was run on a stand in an engine dyno cell measuring HP at the crankshaft WITH a belt driving all the standard accessories that are fitted to a car, are you saying that the engine would produce the same HP with underdrive pulleys as it would with stock pulleys?

Would the engine produce the same amount of crank HP if you replaced the belt-driven mechanical water pump with an electric water pump?

​​​​​​​Would the engine produce the same amount of crank HP if you ran it with no drive belt compared to running it with a belt driving all the standard accessories?

Last edited by Dino Dino Bambino; 03-13-2019 at 05:25 PM.
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Old 03-13-2019, 08:16 PM
  #22  
pascal
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Damn, you Two remind me of the daily head strong debates we used to have in this section.
It was busy indeed, lots of moderating needed. lol
And the fan boys be like "The S197...OMG, OMG! This is the best car Evaaaaar!!"
Fun times...
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Old 03-13-2019, 11:23 PM
  #23  
outceltj
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I posted I believe yesterday and was surprised to see so many other responses. Who says forums are dead. I miss the old days of good debate and conversation on here
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Old 03-14-2019, 01:31 AM
  #24  
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Originally Posted by pascal View Post
Damn, you Two remind me of the daily head strong debates we used to have in this section.
Just when you thought that this forum was becoming rather boring ha ha.
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Old 03-14-2019, 06:23 AM
  #25  
08'MustangDude
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The engine BHP is 320, period. RWHP is maybe 280 with all the parasitic loss. Remove some of that,
with the UDP, you NET more to the wheels, but the engines HP does not go up, it's still 320 HP, but now
RWHP is 295 with the UDP pulley. Engine BHP only increases with a tune, and CAI, turbo or supercharger,
or what makes the engine breathe better, and so on. SO, removing the serpentine belt, you now have no
parasitic loss on accessory pulleys, so now more power will make it to the rear wheels. Going with an electric
water pump, takes no engine HP to drive it, so that's all free for RWHP.

The Dodge HELLCAT Challenger is 707 HP, rated at the crank (BHP). However, it takes 90HP to run the
supercharger alone, so RWHP is already down 90HP. So, even though the engine is putting out 707 HP,
made possible by that supercharger, that supercharger is taking 90HP max to run it. They do not rate the
motor at 617 HP, it's rated at 707 HP. A UDP on this engine would reduce BHP, because the supercharger
pulley RPMs would be reduced.

I am simply saying, a UDP does not add to the engines horsepower rating, it simply frees horsepower,
so more of it gets to the wheels. Dyno the HP at the crank with or without it, it won't change. RWHP
increases, not engine HP. They use fool you words, like performance increase, engine output increase, is not
saying BHP increase, or they would say +15 BHP... They don't, no one who sells UDPs claim it
will increase BHP. They use those "fool you" words to imply it...

If there was a better way to explain it, I would, but I have been working in a performance shop for over
10 years now... Because we know they do not add HP, the guy I work for won't even suggest them, he
goes right for tuning, or forced induction, if you want TRUE horsepower. It's not worth the time and money,
when you can dump that into true horsepower gaining parts. The guy I work for takes out paper and does
the math...

UDP cost -vs- gains, they are not worth the time and money for the gains. A tuner will ADD the 15 HP
you are looking to free up, and be cheaper, with NO labor. If someone gave me a UDP kit, I'd use it, but
I won't spend $480.00 for one. GTs are cheaper, I see them go for well under $200, used. New? Forget
it... You can get tuners for $100, I did... So, I got the +13 HP with the tune, and it only cost me $100
for the InTune1000. You have to take into consideration, do you want the time and effort required to
install a UDP kit for those gains to the rear wheels... So, with that in mind, the guy I work for refuses to sell,
or even mention them...
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Old 03-14-2019, 10:24 AM
  #26  
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Steeda underdrive pulleys retail at $250 and you gain ~9rwhp so at $28 per rwhp, that's pretty good bang for the buck. A DIY mechanic with the correct tools can install them in a couple of hours. Obviously they're useless if you're planning to install a supercharger later on.
Of course the manufacturers claim gains in rwhp because for practical reasons, the pulleys are tested on an engine as installed in a vehicle on a chassis dyno, and any performance gains are documented in drag tests down the 1/4 mile. I can't see underdrive pulley manufacturers paying for dyno tests on an engine mounted on a stand in a dyno cell to find out if they add crank HP, and would the results even matter?
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Old 03-14-2019, 08:04 PM
  #27  
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Originally Posted by Dino Dino Bambino View Post
Just when you thought that this forum was becoming rather boring ha ha.
Well you guys keep the spirit. lol

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Old 03-15-2019, 01:22 AM
  #28  
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DDB: yeah, $250 for a GT, I said they were cheaper, the kit has a smaller crank pulley and
a larger water pump pulley... The one for the 4.0 is $400.00 NEW, without the belt. Buying
the UDP for the 4,0 engine isn't worth it. So, I found a tuner for $100, and was fine. I just
replaced the battery, so I did the idle trim relearn, and it's even better now.
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Old 03-15-2019, 04:34 AM
  #29  
Dino Dino Bambino
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RWHP and performance gains from underdrive pulleys will vary from one vehicle to another. In some cases the return for the buck spent may be too little, and there may be unwelcome side effects like poor charging, poor engine cooling, and poor AC function when idling or crawling in slow traffic.
Fortunately none of these effects have been reported on an 05-10 GT, and I can attest to that from my own experience. As you correctly mentioned, the most popular underdrive pulley kits (Steeda and BBK) consist of a ~25% smaller crank pulley and a larger water pump pulley, thus allowing the stock drive belt to be reused. The alternator, AC, and PS pump are underdriven by 25%, while the water pump is underdriven by a greater degree. The largest portion of the RWHP gain from underdrive pulleys is from the slower spinning water pump.
Here's a YouTube video showing dyno and track results from Steeda underdrive pulleys on a 10 GT. Other tests have shown similar results so this isn't just a flash in the pan video to please the manufacturers.

https://youtu.be/VFbNDRoPkuY

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Old 03-19-2019, 12:24 PM
  #30  
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While I'm sure you guys aren't having the time of your life debating this, I truly am enjoying it because I now understand it more than I ever have. I've done some searching around, this is a VERY interesting thread gentlemen! Personally, i just want to know how much HP hits the road from my rear tires. However, the defined HP at different points on the car is interesting to me.
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