1BAD3V

Does anyone know why the 99/01 Cobras redline is 6800, but the 03/04 Cobras is only 6500. You would think that the Terminator would have a higher redline for the S/C, but guess not. Oh and what is the redline on a Mach 1? Thanks

COMPMACH

I would think the redline for the mach would be the same as the 99-01 cobra,because i believe its the same motor.

1BAD3V

The 99/01 Cobra, 03/04 Cobra and 03/04 Mach 1 all have the same motor. Just the 03/04 Cobra is S/C and has forged internals, and the 5spd Machs have forged cranks.

GreyStang

Maybe it's because the blower motor doesn't NEED to rev as high to smoke the competition?

1BAD3V

LOL, that is a good point, just wonder if its true or not, You would think SVT would have made it rev to like 7500 or something just so it could be in the high rpms for longer, but then again it has a S/C, so it loves any rpm range.

PushinTheLimit

One reason as I'm sure why this was done was because of heat issues. The higher the rpms, the faster the blower is gonna spin... which causes more heat. I'm sure that with a tune, you could up the redline a lil, but I really don't think its moved very much. The Eaton almost becomes a heater at a certain point. Thats why if you plan to do alot of WOT blasts or race it, its best to get some cooling mods to compliment the Eaton or go with a Twin Screw to help out the efficiency as well. I'm sure someone with a lil more experience can answer this better, as I'm learning about the 03/04 Cobra's myself.

CobraBob

The '03/'04 cobra wasn't intended to rev to 6800 rpms like the '99 because the Eaton blower builds HP/TQ at lower rpms and the cams aren't set-up for higher revs. Laying aside the blower, the '03/'04 motor is built strong enough to handle, say, 7000 rpms. It is more an issue of efficiency. Why rev higher when the stock heads, combined with the forced induction power adder (blower), can't make much power above this rpm range? Also, while the '03/'04 block has good crank & rods, the pistons are weak. IMO if Ford had decided to go with a NA motor for the '03/'04 Cobra, the redline would have been somewhere in the 6,800 - 7,000 range.

As far as blower rpms, consider that a stock '03 Cobra spins the blower (8-9lbs. of max boost) at 13,534 rpms at redline. The same car making 15 lbs. of boost (considered the limit for the stock blower) spins the blower at 17,643 rpms. Now consider how fast the blower (at 15 lbs. boost) would be spinning if redline were 6,800 rpms. Unless my simple math is off, that would mean the blower would be spinning at just under 18,525 rpms. That is seriously overspinning the stock Eaton. If you port the blower and make it efficient enough to handle a max of 17 lbs. of boost, the blower would then be spinning at 20,024 rpms at the stock redline and 21,025 rpms at the 6,800 rpms. Egads! I realize my math above doesn't take into consideration upper rpms factors related to the valvetrain, but I think the point about the blower being a major fact is quite clear.

PushinTheLimit

Ah yes... CobraBob to the rescue. You have some of the greatest advice and comments for everyone to learn from. I didn't realize how fast the Eaton would be spinning with that amount of boost[&:]. No wonder many guys go twin screwed.

amoosenamedhank

That's not exactly true either. The engines use different heads. One for the 99/01 cobra and different one for the 03/04 cobra and mach 1.

PWORLDSTANG

Well put goldeneagle and Cobra Bob. Another big issue with the Eaton is HEAT. A lot of heat is being soaked up at RPM's that high. Heat is a weakness of the Eaton. That's why a lot of 03-04 Cobra owners port the blower for better efficiency.