meaty mac said:
Your hurting me... inside... Your hurting me...
Besides, what is he going to do... Ebeat me up? :shrug: I mean come on fellas.
Rumor has it GT500 make 638 rwhp with mods
- Thread starter 03Terminator
- Start date
Your hurting me... inside... Your hurting me...
Besides, what is he going to do... Ebeat me up? :shrug: I mean come on fellas.
snatchss454 said:
I think you can, however, how do you account for an increase in boost? Does that effectively make you blower larger? I have thought about this for hours.
what happens if you increase boost to more than 14.7psi? That would theoretically make the amount of air being forced in 2atm, which when you think about it is double the amount a n/a engine of the same size would. Does that make your engine twice as large. So in all actuality a 5.4 s/c motor is effectively larger than the 7.0L form chevy. Would upping the boost make it even larger? :shrug:
It would be nice if a blower expert could chime in on this.
I posted this on another forum, but here is my take on it.
Don't forget whenever you comparing displacement to displacement, i.e. 4.6L vs 5.4L the difference of .8L becomes smaller when you consider that the 4.6L has potential to run at a bit higher rpm(what you lack in displacement you can run at a higher rpm).
On the 4.6L, the pullied eaton could not keep up with the motor as the horsepower would nose over way before the engine hit redline. It was just not moving through enough air. Porting the blower alleviated that a bit but still no match for the flow of the 4.6L heads. Spinning the blower any faster would have produce a lot more heat with no increase in horsepower. So as someone stated before, the max horsepower might be limited to the blower and this new blower is similiar to the old one. Then the situation now becomes 5.4L heads>4.6L heads> both old and new blowers. You simply run out of blower before head restrictions become a problem.
Suppose the new blower is 15%(claimed by eaton) more efficient than the old one and lets say this motor puts out 450rwhp. That's about 59rwhp difference from the new blower if you back calculate 390rwhp x 1.15% to get to 450rwhp . That's enough to cover a little bit more than the 250lb weight spread between the 03/04 cobra and the new shelby. In the end, eaton vs. eaton, we might be looking at a similiar outcome (slight nod to shelby though)with max effort bolt-ons, i.e., low 11s at mid 12xmph with 530rwhp(3664lb) vs 600rwhp(3920lb). Utilizing a larger aftermarket blower would be a whole different story though.
Also something to think about. You can see gains of 50+hp by porting the old eaton. How much more can you gain out of the new eaton by porting it being that they already improved on the old design?
So what do you think? Am I right or wrong?
Don't forget whenever you comparing displacement to displacement, i.e. 4.6L vs 5.4L the difference of .8L becomes smaller when you consider that the 4.6L has potential to run at a bit higher rpm(what you lack in displacement you can run at a higher rpm).
On the 4.6L, the pullied eaton could not keep up with the motor as the horsepower would nose over way before the engine hit redline. It was just not moving through enough air. Porting the blower alleviated that a bit but still no match for the flow of the 4.6L heads. Spinning the blower any faster would have produce a lot more heat with no increase in horsepower. So as someone stated before, the max horsepower might be limited to the blower and this new blower is similiar to the old one. Then the situation now becomes 5.4L heads>4.6L heads> both old and new blowers. You simply run out of blower before head restrictions become a problem.
Suppose the new blower is 15%(claimed by eaton) more efficient than the old one and lets say this motor puts out 450rwhp. That's about 59rwhp difference from the new blower if you back calculate 390rwhp x 1.15% to get to 450rwhp . That's enough to cover a little bit more than the 250lb weight spread between the 03/04 cobra and the new shelby. In the end, eaton vs. eaton, we might be looking at a similiar outcome (slight nod to shelby though)with max effort bolt-ons, i.e., low 11s at mid 12xmph with 530rwhp(3664lb) vs 600rwhp(3920lb). Utilizing a larger aftermarket blower would be a whole different story though.
Also something to think about. You can see gains of 50+hp by porting the old eaton. How much more can you gain out of the new eaton by porting it being that they already improved on the old design?
So what do you think? Am I right or wrong?
immortalstang said:
A built 4.6 with 500rw at peak would be eaten alive by a similarly built 500rw 5.4 because of the difference in avg. HP/TQ. 250 extra rpm up top will in no way compensate for the difference.
why dont you just admit that you were wrong about the engine. i notice that you didn't address that issue. as far as Ebeating you up, does that mean that you can be ignorant, just because you are safely behind your computer? i don't get it. this forum has got too much class in it to turn into another LS1 forum. aren't we all on the same team here? come on bud, lets play fair. remember, it's the wise man who listens more than he speaks...but when he does speak, it's golden! :read:03CobraBro said:
Fourcam330 said:
Agreed, I was thinking removing the rev limiter to gain a little more, but both would have pretty flat torque curves don't you think? 500rwtq on 4.6L would be similiar to 500rwtq by the 5.4L because both have relatively flat area under the curve. Offset this by the couple of hundred pounds between the new and old cobras and you have similiar running cars, although I still think the shelby will edge out the terminator.
immortalstang said:
Even if both motors had 500rwtq @ peak, the 5.4 would still make more avg. hp/tq than the 4.6.
All things equal, both motors would have flat torque curves, but the 5.4 would be substantially fatter through the entire range. Remember that at any equivalent rpm, the 5.4 is moving roughly 15% more air than a 4.6 could; which may not sound like a lot, but is in fact a huge difference.
I've never seen a stock blower (even ported) equipped 03/04 with the power to run 130mph traps at stock weight which is obviously substantially less than the GT500.
Not dogging the terminators, but as always happens with newer models, time marches on. Come this summer the bar will officially be raised.
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No, you can't just add the displacements. It depends on how fast the blower is spinning. An effective displacement can be defined by:snatchss454 said:
CIDe,eff = CIDe*(1 + Pboost/Patm).
So for the '03's which typically run ~9 psi stock, (mine was ~9.5), you'll get:
CIDe,eff = 281*(1 + 9/14.7) = 453 cid
For the Shelby with 8.5 psi (which will probably be more), you'll get:
CIDe,eff = 329*(1 + 8.5/14.7) = 519 cid
BTW, boost pressure for a Roots-type blower is given by:
Pboost = Patm*[2*PR*(CIDsc*VEsc)/(CIDe*VEe) - 1]
Does that help?
Black2003Cobra said:
So in my thinking I was right. assuming sea level. if you were to up the boost on the GT500 to 14.7 psig you would be effectvely making the motor 2x (658") larger? YOu would be forcing twice as much air in the motor compared to N/A.
A kb (2.4) 4.6 cobra putting out 20psig would be 663" if N/A. Right?
damn, so by that thinking my engine is really 980"
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GTSpartan said:So in my thinking I was right. assuming sea level. if you were to up the boost on the GT500 to 14.7 psig you would be effectvely making the motor 2x (658") larger? YOu would be forcing twice as much air in the motor compared to N/A.
A kb (2.4) 4.6 cobra putting out 20psig would be 663" if N/A. Right?
damn, so by that thinking my engine is really 980"
Right-O.
To be fair though, one needs to keep in mind that although you're shoving in, say, twice the air, that doesn't mean twice the brake power. (Indicated power would double for twice the air (and fuel), but the pumping loss from the blower goes up, which means a drop in overall mechanical efficiency, and hence, less brake power.)
Black2003Cobra said:
Dam dude...Way to make me feel stupid(J/K). I mean I couldnt even understand what you wrote until you broke it down. I need to go back to school. :read: ....oh who am I fooling itd just be more of the same :beer: and :banana:
MPG...
This is what I am thinking about. Ford can get by with the GT making 21 MPG, but the GT500 will need to be close to that or better on the Highway for the class of car that it is. I can't see it passing emissions with less than 21 mpg highway. So I look at it like this. The engine has a similar potential as the Ford GT, but something will have to give either in the tune or something that will get it in compliance. The GT500 weighs more, and is less aerodynamic than the Ford GT, so that will hurt it's MPG as well. I don't know if this will indeed have any bearing. Maybe they will put it on the street making sub 20 MPG highway, which would be close to 11-12 or so in the city. This is just a thought I had, and I really don't know what the facts are, but some of you with more knowledge might be able to give this some light.
-Jeff
This is what I am thinking about. Ford can get by with the GT making 21 MPG, but the GT500 will need to be close to that or better on the Highway for the class of car that it is. I can't see it passing emissions with less than 21 mpg highway. So I look at it like this. The engine has a similar potential as the Ford GT, but something will have to give either in the tune or something that will get it in compliance. The GT500 weighs more, and is less aerodynamic than the Ford GT, so that will hurt it's MPG as well. I don't know if this will indeed have any bearing. Maybe they will put it on the street making sub 20 MPG highway, which would be close to 11-12 or so in the city. This is just a thought I had, and I really don't know what the facts are, but some of you with more knowledge might be able to give this some light.
-Jeff
HISSMAN said:
Chrysler does that and seems to still sell its stuff. I.E. EPA estimates can be tweaked... :-D
Just a few brief comments on fuel efficiency.
Obviously weight is bad:
Higher weight means more energy to accelerate to a given speed, KE = 0.5*m*v², which requires more fuel. (This KE is then lost in the form of heat energy when you hit the brakes.)
Rolling resistance loss is also directly proportional to weight, so higher mass = lower mpg here, too.
Aerodynamic drag is directly proportional to Cd and frontal cross section area, so both of these can ping mpg.
Higher mass also means a greater road inclination loss, (going up hills). So again…lower mpg.
Then there’s perhaps the not so obvious.
Moving a given mass at a given speed requires a given amount of power to overcome the “road load”, (i.e., rolling resistance, aero loss, road inclination loss, etc.). And to make a given amount of indicated power takes a given mass fuel (and air) flow rate. But because a larger engine is going to have a lower mechanical efficiency, (due primarily to higher pumping* and frictional losses), this means a lower brake power for a given mass fuel rate. Therefore, to generate the required brake power with a lower mechanical efficiency means a higher amount of indicated power, which means a higher mass fuel flow rate. Ergo, lousy mpg again.
The lower static CR of a blower engine reduces the thermal-conversion efficiency of the motor. This means a lower fuel-conversion efficiency (compared to a higher compression NA engine), which once again means a higher fuel consumption.
*Pumping loss is the energy required to pump air in to, and exhaust out of the engine. Since a larger engine will be throttled back more to make a given amount of power, this means a higher pumping loss. Larger frictional losses with a bigger engine should be obvious.
Obviously weight is bad:
Higher weight means more energy to accelerate to a given speed, KE = 0.5*m*v², which requires more fuel. (This KE is then lost in the form of heat energy when you hit the brakes.)
Rolling resistance loss is also directly proportional to weight, so higher mass = lower mpg here, too.
Aerodynamic drag is directly proportional to Cd and frontal cross section area, so both of these can ping mpg.
Higher mass also means a greater road inclination loss, (going up hills). So again…lower mpg.
Then there’s perhaps the not so obvious.
Moving a given mass at a given speed requires a given amount of power to overcome the “road load”, (i.e., rolling resistance, aero loss, road inclination loss, etc.). And to make a given amount of indicated power takes a given mass fuel (and air) flow rate. But because a larger engine is going to have a lower mechanical efficiency, (due primarily to higher pumping* and frictional losses), this means a lower brake power for a given mass fuel rate. Therefore, to generate the required brake power with a lower mechanical efficiency means a higher amount of indicated power, which means a higher mass fuel flow rate. Ergo, lousy mpg again.
The lower static CR of a blower engine reduces the thermal-conversion efficiency of the motor. This means a lower fuel-conversion efficiency (compared to a higher compression NA engine), which once again means a higher fuel consumption.
*Pumping loss is the energy required to pump air in to, and exhaust out of the engine. Since a larger engine will be throttled back more to make a given amount of power, this means a higher pumping loss. Larger frictional losses with a bigger engine should be obvious.
I wonder if the gas guzzler tax will apply. The 03 Terminator EPA was 23 mph highway and was subject to the tax. The 04 was 24 mpg and wasn't. The 3.31:1 gears was probably Ford's method to push the highway mileage up. Did they lower the ratios in the first few gears to make up for the loss in torque multiplication?
Yeah, the lower first gear on the Shelby actually more than makes up for the reduced diff gearing. On the '03 and '04 the overall ratio in first is 3.55x2.66 = 9.44. On the Shelby it's 3.31x2.97=9.83, so more tq multiplication, (but only in first. The rest of the xmission gearing is the same.) I had to pay the guzzler tax on my '03. Sucks! I guess we'll soon see on the Shelby, but it wouldn't surprise me.
Black2003Cobra
You are a technical manual with leggs. Being and engineer I know you're void of any emotion. If you’re married I bet it drives your wife nuts. She gets hysterical while you calmly asses the situation and apply logic.
They hate that :beer:
You are a technical manual with leggs. Being and engineer I know you're void of any emotion. If you’re married I bet it drives your wife nuts. She gets hysterical while you calmly asses the situation and apply logic.
They hate that :beer:
Black2003Cobra said:
I was wondering if the 6 speed might benefit the GT500 for the gas guzzler tax. The tax is figured based on the average of the city mpg and the highway mpg correct? If that is true then could it be possible the 6 speed will help with the city mpg more? Of course this would depend on the gearing of each one as well.
I am not as knowledgeable on car stuff like this....although I understood most of what Black2003Cobra said. :read:
....at least I think I did...
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