How much boost can the new V-8 handle (theoretically)???

torqueIT

New Member
Jan 9, 2004
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Phoenix, Arizona
Can anyone supply a guestimate on just how much boost the GT V-8 might be able to handle? Obviously, we won't know real numbers till fall of this year, but basing in on current 5.0 Mustangs, what do you figure the new Mustang V-8 might be able to handle?

I've seen 4-bangers handle upwards of 20psi, but I have to admit, the V-8s are a mystery to me :shrug:

Usually I figure you can see around 10hp per 1psi for 4 cylinder engines, does this also figure around the same ratio when boosting a V-8, or can I expect a bigger conversion ratio?
 
14 with a good tune reliably i guess. intercooled turbo boost > super boost. i thought it was like 12.5hp/psi but i guess it varies. 300+(14*12.5)= 475hp ???
 
14 to 22 psi eh?

Very interesting. I honestly thought more would be possible with a bigger bored engine, not that I'm complaining!

Still if 14-22psi is a possibility then at the 12.5hp ratio that AXIStang mentioned (575 hp max) not bad, not bad at all!

With a few more mods, theoretically you could mod a GT to push 600hp, with bolt-ons only, potentially on pump-gas!

NICE! :nice:
 
Do the aftermarket systems run that much boost? I always thought with a stock compression ratio, the paxton vortech systems generally ran much less. Keep in mind, cars that come from the factory with a blower generally run between 7:1 to maybe 8.5:1 compression.

I don't really buy the "hp/pounds of boost" thing. Too many outside variables.

Ford GT makes 500hp/500 lbs-ft TQ with a 5.4L engine, 8.4:1 compression running up to 12psi boost.

The mustang has a compression ratio of 9.8:1. If you tried to run 22 lbs of boost, you'd blast you spark plugs into low earth orbit.
 
Since it has 9.8:1 compression. Who's going to have the first thicker head gasket to drop the compression. I'm looking toward running a decent amount of boost.:D
 
MrMorden said:
At 9.8 compression it will be okay at 8psi, 10psi will be pushing it.

I would think so. From pic's Iv'e seen, the new 4.6L block is basically a decked version of the 5.4L block in the Ford GT. In other words, It's probably strong as hell. They also say the new 3V combustion chamber is much more resistant to knock than the 2 valve. Think about it: 9.8:1 compression on 87 octane is very good.

All good news for those adding a blower.
 
There is not a hard and fast # on how much boost you can run with the 9.8:1 compression ratio.

The 2005 engine with it's 9.8:1 CR runs on 87 octane, just like the 2V runs on regular with 9.4:1 CR. The 3V is able to use a higher CR because of it's more central spark plug location and improvements in the engine controls.

The biggest problem you guys who want to add a S/C are going to have is getting new PCM code. The 2005 uses a different engine control system than prior Mustangs. You will not be able to "chip" it. The only way to have the engine respond to a S/C will be to have new PCM sofware that knows about the increased air flow from the S/C.

This is the same PCM system that the Lincoln LS, T-Bird and 2004 F-150 use. So far no aftermarket company has been able to re-program this PCM. You will most likely have to wait for someone like Ford Racing or Roush to come out with a S/C kit that includes revised PCM sofware.
 
351CJ said:
There is not a hard and fast # on how much boost you can run with the 9.8:1 compression ratio.

The 2003 engine with it's 9.8:1 CR runs on 87 octane, just like the 2V runs on regular with 9.4:1 CR. The 3V is able to use a higher CR because of it's more central spark plug location and improvements in the engine controls.

The biggest problem you guys who want to add a S/C are going to have is getting new PCM code. The 2003 uses a different engine control system than prior Mustangs. You will not be able to "chip" it. The only way to have the engine respond to a S/C will be to have new PCM sofware that knows about the increased air flow from the S/C.

This is the same PCM system that the Lincoln LS, T-Bird and 2004 F-150 use. So far no aftermarket company has been able to re-program this PCM. You will most likely have to wait for someone like Ford Racing or Roush to come out with a S/C kit that includes revised PCM sofware.


I guess there are two ways to do it:

1. The aftermarket would have to build a complete ECM to replace the stock one (cha-ching!).

or

2. The aftermarket would do a piggyback ecm that is wired in series with the stock ecm and harness. There are other aftermarket performance companies doing this for various automotive applications. Jackson Racing does one but I won't mention for who (hint: starts with an "H", ends with an "ONDA") or what (start with a "V"...) because some people seem to be alergic to those phrazes.

This could probably be done more economically, but, still more expensive and harder to install than a chip.
 
Wait till the car comes out, then when the aftermarket and the REAL people have experienced these items... you man then do whatever is best.

If ford throws in powdered rods and cast crap pistons... dont even THINK of going past 400rwhp. It is KABOOM and living on a limp leg with anything more.

Theoretically I say nothing more than 8psi without problems. (read: not living minute by minute)
 
351CJ said:
There is not a hard and fast # on how much boost you can run with the 9.8:1 compression ratio.

The 2003 engine with it's 9.8:1 CR runs on 87 octane, just like the 2V runs on regular with 9.4:1 CR. The 3V is able to use a higher CR because of it's more central spark plug location and improvements in the engine controls.

The biggest problem you guys who want to add a S/C are going to have is getting new PCM code. The 2003 uses a different engine control system than prior Mustangs. You will not be able to "chip" it. The only way to have the engine respond to a S/C will be to have new PCM sofware that knows about the increased air flow from the S/C.

This is the same PCM system that the Lincoln LS, T-Bird and 2004 F-150 use. So far no aftermarket company has been able to re-program this PCM. You will most likely have to wait for someone like Ford Racing or Roush to come out with a S/C kit that includes revised PCM sofware.
Just curious, you keep referring to a 2003 engine?

What 2003 engine?
 
yellow5.0cobra said:
Wait till the car comes out, then when the aftermarket and the REAL people have experienced these items... you man then do whatever is best.

If ford throws in powdered rods and cast crap pistons... dont even THINK of going past 400rwhp. It is KABOOM and living on a limp leg with anything more.

Theoretically I say nothing more than 8psi without problems. (read: not living minute by minute)

That's the real point I guess. If you're willing to put in a forged steel crank, forged rods and lower compression forged pistons, upgraded the fuel system and ecm, you could probably get 600 streetable hp out of one of these engines. Will it last 100k miles before a rebuild? The better question is: if you can afford to dump that kind of money into it, would you care?

A friend of mine recently put a dinan blower in his M3. This system runs around 8 psi boost and is generally regarded as being one of the better installations around. Someone suggested he should install a smaller pulley, giving him more boost and maybe another 30-50 hp. He talked this over with his mechanic and was advised against it. The mechanic suggested, and rightly so, that the Dinan people know how to design these systems to provide the best power, streetability and reliability. If adding the smaller pulley was such a good idea, they could have easily done it themselves. When you start second guessing the people that design these systems, especially when you start getting into the 100bhp/litre range, don't be surprised when things start getting a bit random.

An 05 mustang gt running 6-8 psi boost (call it 400hp, give or take), sounds more than reasonable to me.
 
shatner saves said:
I guess there are two ways to do it:

2. The aftermarket would do a piggyback ecm that is wired in series with the stock ecm and harness. There are other aftermarket performance companies doing this for various automotive applications. Jackson Racing does one but I won't mention for who (hint: starts with an "H", ends with an "ONDA") or what (start with a "V"...) because some people seem to be alergic to those phrazes.

This could probably be done more economically, but, still more expensive and harder to install than a chip.

I don't know if this will really work. The new Ford PCM allows for limited adjustment of some parameters A/F etc., throught the ODB-II port, but the available asjustment range will not handle anything of the magnatude of a power adder.

The easiest and lowest cost way to do this would be to modify the PCM engine calibration tables and / or the PCM code itself. So far no one outside of Ford has been able to do this. However since the Mustang is much more of an aftermarket performance add on vehicle than the other FoMoCo products that use the new PCM, I'd day that a lot more people are going to try to break the PCM code.

Somewhere I read a quote from a Team Mustang member who said that the 2005 PCM will respond to limited modification such as exhaust & CAI. He also said that they (Ford engine people) would be working with Ford Racing to provide new calibration tables and / or different PCM code to handle power adders (purchase from Ford Racing).
 
I've heard a few people say, 'just wait till it comes out, and then you can get some real numbers'. Notice the post said (theoretical) :D

Most people here are just shootin the breeze (kinda makes it easier to wait till the Mustang actually does make it to the showroom floor).

Obviously solid numbers are just a shot in the dark, so to speak. I'm just interested in the very rough numbers for now. Takes the edge off! :bang: