Supercharging the 5.0 and no modifications needed.

[65mph_Roll]

why not? the only thing that's limited is the amount of boost you can run, NOT the amount of power you can make vs the inverse. if low compression/high boost was the "only" way to do it, then we would be running some stupid crap like 50PSI into a 4 to 1 compression engine.

really, high boost/low compression isn't any better or worse than low boost/high compression. they are both just a means to an end. the engine compresses air and the supercharger compresses air. all your doing is switching up which one does the most work.

So you are saying that "conventional wisdom" is wrong? And, why does every purpose-built forced induced factory made car start with about 8:1 to 9:1?? The (the new ZR1 is 9.1:1 and the Bugatti Vetron is 9:1 and the Shelby GT500 Super Snake is 8.4:1).

Sure, you can 'tune around' higher compression, but starting with a clean sheet of paper and conventional wisdom dictates a lower static compression ratio.

I love the new 5.0, I just think Shelby went for the easy bolt on instead of changing the pistions...

 

[ChiSVT]

I don't understand this obsession with positive displacement blowers. If you're going to spend $7,8, $9,000 why go with the least efficient power adder? Get a twin turbo kit! Less heat, more efficient, more power!

 

[65mph_Roll]

why not? the only thing that's limited is the amount of boost you can run, NOT the amount of power you can make vs the inverse. if low compression/high boost was the "only" way to do it, then we would be running some stupid crap like 50PSI into a 4 to 1 compression engine.

really, high boost/low compression isn't any better or worse than low boost/high compression. they are both just a means to an end. the engine compresses air and the supercharger compresses air. all your doing is switching up which one does the most work.

And by your logic of, "stupid crap like 50PSI into a 4 to 1 compression engine", why not 17:1 and no blower at all!!

Forced induction w/11:1 is simply not ideal. It can be made to work, but far more could be had with a more optimumal 8-9:1 base static compression and more boost.

It's just the result of an N/A motor with a bolt-on blower maxed out. Shelby should have changed to lower compression forged pistions for the premium he's going to collect. And, let us run 8lbs low boost / 12lbs mid / 16-18+ crazy!

 

[65mph_Roll]

I don't understand this obsession with positive displacement blowers. If you're going to spend $7,8, $9,000 why go with the least efficient power adder? Get a twin turbo kit! Less heat, more efficient, more power!

In CA anyway, they're legal at smog check time. No hassles. I'd love a turbo too.

 

[Driver72]

In CA anyway, they're legal at smog check time. No hassles. I'd love a turbo too.

They are or they aren't legal at smog check time?
Luckily if illegal you don't have to smog check a new car in CA.
I think the car has to be 5 years old before a smog is required.
But I'm not sure, I haven't owned a 5+ year old car in many years.

Yes, a twin turbo set up on the 5.0 would be badass for sure.
S/C are great for instant boost, but they sap too much power in the process.

 

[Ry_Trapp0]

So you are saying that "conventional wisdom" is wrong? And, why does every purpose-built forced induced factory made car start with about 8:1 to 9:1?? The (the new ZR1 is 9.1:1 and the Bugatti Vetron is 9:1 and the Shelby GT500 Super Snake is 8.4:1).

Sure, you can 'tune around' higher compression, but starting with a clean sheet of paper and conventional wisdom dictates a lower static compression ratio.

I love the new 5.0, I just think Shelby went for the easy bolt on instead of changing the pistions...

And by your logic of, "stupid crap like 50PSI into a 4 to 1 compression engine", why not 17:1 and no blower at all!!

Forced induction w/11:1 is simply not ideal. It can be made to work, but far more could be had with a more optimumal 8-9:1 base static compression and more boost.

It's just the result of an N/A motor with a bolt-on blower maxed out. Shelby should have changed to lower compression forged pistions for the premium he's going to collect. And, let us run 8lbs low boost / 12lbs mid / 16-18+ crazy!

if this was the late 50's, you would be the guy saying "screw OHV engines, flathead is obviously the way to go because we've optimised them over these last few decades". just because we've been doing it for years this way' doesn't mean it's the best way?

my logic is supported by many others that are far smarter than either of us...

"Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular."
MotorSports Digest(great article, read the whole thing)

there is absolutley nothing more optimal about a low compression engine for boost than a high compression engine. like i said, a supercharger is an air compressor, and a piston engine(or any internal compression engine for that matter) is an air compressor, there is no "secret magic" going on here.
besides some of the top modular guys are starting to look at higher compression in boosted applications(dan schoeneck, for example, who is building a high compression 5.4l for his procharged ford GT). even some of the big power GT500 guys are upping their compression when getting their engine built. in fact, john mihovetz is running over 11 to 1 on his 2,300+HP 4.6l.

 

[Sir Nate 3000]

^^ +1

I've been saying this but the reply I get is, "a high compression motor won't handle the boost or won't make as much power or a high compression motor is not made for boost, etc."

I'd rather have a high compression motor that makes good power n/a, then supercharge or turbocharge it. that way I don't have to spin the heck out of a blower or run a big turbo to 30psi :shrug:

 

[csledd]

^^ +1

I've been saying this but the reply I get is, "a high compression motor won't handle the boost or won't make as much power or a high compression motor is not made for boost, etc."

I'd rather have a high compression motor that makes good power n/a, then supercharge or turbocharge it. that way I don't have to spin the heck out of a blower or run a big turbo to 30psi :shrug:

I guess I'm just curious what numbers we'll see with the high compression low boost set up. It would be awesome to see close to 580ish rwhp on a 5.0 with the usual bolt ons and low boost, but I'm not sure if that's too high.

 

[65mph_Roll]

if this was the late 50's, you would be the guy saying "screw OHV engines, flathead is obviously the way to go because we've optimised them over these last few decades". just because we've been doing it for years this way' doesn't mean it's the best way?

my logic is supported by many others that are far smarter than either of us...

"Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular."
MotorSports Digest(great article, read the whole thing)

there is absolutley nothing more optimal about a low compression engine for boost than a high compression engine. like i said, a supercharger is an air compressor, and a piston engine(or any internal compression engine for that matter) is an air compressor, there is no "secret magic" going on here.
besides some of the top modular guys are starting to look at higher compression in boosted applications(dan schoeneck, for example, who is building a high compression 5.4l for his procharged ford GT). even some of the big power GT500 guys are upping their compression when getting their engine built. in fact, john mihovetz is running over 11 to 1 on his 2,300+HP 4.6l.

Ry Trapp0

OK, I’m keeping an open mind here (I have a buddy with a big single Supra making 777RWHP who also says static compression is on the way up a bit for forced induced motors, he’s @ 9.5:1 with a turbo the size of a basketball)

Anyway, it’s a dynamic engineering problem for sure. Interesting point though about having to spin the blower less for less parasitic loss.

But from an economic standpoint I just get the feeling that the tuner cars and aftermarket are just plain stuck with higher compression cars now and need to somehow make it work (in a bolt-on way).

How about this: if you had a new GT500 and wanted to “max it out” with a twin screw generous budget, would you raise the static compression ratio?

 

[Driver72]

"Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular."
MotorSports Digest(great article, read the whole thing)

Good post and good information. I for one did not know that, as I was always trusting of the old school belief of needing to have a lower compression to boost optimally.
But that part of article makes sense.
Thanks for posting it.

 

[HP Solutions]

if this was the late 50's, you would be the guy saying "screw OHV engines, flathead is obviously the way to go because we've optimised them over these last few decades". just because we've been doing it for years this way' doesn't mean it's the best way?

my logic is supported by many others that are far smarter than either of us...

"Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular."
MotorSports Digest(great article, read the whole thing)

there is absolutley nothing more optimal about a low compression engine for boost than a high compression engine. like i said, a supercharger is an air compressor, and a piston engine(or any internal compression engine for that matter) is an air compressor, there is no "secret magic" going on here.
besides some of the top modular guys are starting to look at higher compression in boosted applications(dan schoeneck, for example, who is building a high compression 5.4l for his procharged ford GT). even some of the big power GT500 guys are upping their compression when getting their engine built. in fact, john mihovetz is running over 11 to 1 on his 2,300+HP 4.6l.

Turbos and Superchargers are much more efficient at compressing air than a piston/rod internal combustion motor. This is why engineers lower the compression ratio and rely on turbos and superchargers to add the air more efficiently (i.e. less heat) so pump gas can be ran. High compression ratio with boost is possible, but detention will be much more likely because of the heat. Race cars can get away with high compression and a lot of boost because they use race gas.

Josh

 

[chrisheltra]

Why not do both Im running nearly 10.1:1 and 18# on pump gas in the L and I DD it. lol

 

[OCSnk]

Great info and topic:beer:

What is the compression#’s of the 03-2011 Cobra’s and what for example are Mercedes running on their factory superchargers engines.

 

[GTSpartan]

With good fuel and internals, high c/r and boost is awesome.

The best of both worlds

 

[HP Solutions]

With good fuel and internals, high c/r and boost is awesome.

The best of both worlds

Most definitely, but street driven factory cars cant run high octane fuel. That is why for 91-93 octane with 8.5:1 and boost, will make good power.

 

[Ry_Trapp0]

Turbos and Superchargers are much more efficient at compressing air than a piston/rod internal combustion motor. This is why engineers lower the compression ratio and rely on turbos and superchargers to add the air more efficiently (i.e. less heat) so pump gas can be ran. High compression ratio with boost is possible, but detention will be much more likely because of the heat. Race cars can get away with high compression and a lot of boost because they use race gas.

Josh

your absolutely right about compressor efficiency, but there is much more useable power with a higher compression ratio. if your building a strip or bonneville only car, then, sure, pour the boost to it, but in most other applications the useable power gained with the higher compression ratio will be more beneficial than the small efficiency gain of a high boost application. in either case, the peak HP should be pretty close, and the peak torque should favor the higher compression engine.

either way, it's undeniable that high compression/lower boost is the current trend, at least in the modular world anyways.

 

[OCSnk]

your absolutely right about compressor efficiency, but there is much more useable power with a higher compression ratio. if your building a strip or bonneville only car, then, sure, pour the boost to it, but in most other applications the useable power gained with the higher compression ratio will be more beneficial than the small efficiency gain of a high boost application. in either case, the peak HP should be pretty close, and the peak torque should favor the higher compression engine.

either way, it's undeniable that high compression/lower boost is the current trend, at least in the modular world anyways.

The problem is; no one keeps them at the lower prescribed levels of boost. People start off at 6 to 8, soon to crank it up at 12 typically :whine:

 

[Driver72]

The problem is; no one keeps them at the lower prescribed levels of boost. People start off at 6 to 8, soon to crank it up at 12 typically :whine:

I think 6-7 psi boost on the 11:1 compression 11 GT is plenty.
That should be worth 525-550 crank hp with no other mods.
Add intake, exhaust, headers and meth (along with supporting tune) and you are well over 600 crank hp.

Anybody need anymore than that for the weekend racer or in a DD just wants d1ck waving bragging rights at that point.
600 hp in a DD car that's 3600 lbs gets to be a handful and actually tough to drive sanely around other cars that have 150-250 hp.

Dedicated drag racers, sure go for more, but other than that, I feel it's just about ego at that point (and even up to that point).

 

[HP Solutions]

I think 6-7 psi boost on the 11:1 compression 11 GT is plenty.
That should be worth 525-550 crank hp with no other mods.
Add intake, exhaust, headers and meth (along with supporting tune) and you are well over 600 crank hp.

Anybody need anymore than that for the weekend racer or in a DD just wants d1ck waving bragging rights at that point.
600 hp in a DD car that's 3600 lbs gets to be a handful and actually tough to drive sanely around other cars that have 150-250 hp.

Dedicated drag racers, sure go for more, but other than that, I feel it's just about ego at that point (and even up to that point).

Having "enough" horsepower is an opinion I guess :banana:

I wouldn't mind having 800hp on a daily driver.

your absolutely right about compressor efficiency, but there is much more useable power with a higher compression ratio. if your building a strip or bonneville only car, then, sure, pour the boost to it, but in most other applications the useable power gained with the higher compression ratio will be more beneficial than the small efficiency gain of a high boost application. in either case, the peak HP should be pretty close, and the peak torque should favor the higher compression engine.

either way, it's undeniable that high compression/lower boost is the current trend, at least in the modular world anyways.

With a positive displacement blower you have plenty of "usable" power.

I will assure you that if you are running pump gas, with high comp/ low boost versus low comp/ higher boost; that you will make much more power on low comp/ high boost.

I will say higher compression ratio will be beneficial with a turbo car for sure, but positive displacement, not so much.

 

[GTSpartan]

I will assure you that if you are running pump gas, with high comp/ low boost versus low comp/ higher boost; that you will make much more power on low comp/ high boost.

As long as the cylinder pressures are the same, you'll make the same power.

I will say higher compression ratio will be beneficial with a turbo car for sure, but positive displacement, not so much.

How so, air pressure is air pressure, no matter how it's pumped in.