[mustang_mike]

Hi Guys and Gals,

I have a 1998 Cobra Convertible with a Vortech supercharger blowing about max 8 psi. The engine is otherwise stock (with full exhaust mods and lots of suspention & chassis mods). The transmission is stock, with an aluminum driveshaft to 4.10 gears.

Here's where you all will think I am CRAZY! The 4.10 gears went in before the supercharger. With the stock 5-speed gear ratios (not quite ready to do a TKO 6 change just yet) she spins them in THIRD. Sweet as that is, I am set on a steet/highway cruiser and not a weekend strip monster. That's not to say I don't want a fast car!

So, here goes: I have decided on two mods. 3:55 rear gear, and a few more ponies to offset the gear change. I've read dyno results on a naturally aspirated Cobra motor that state "upgrading" the throttle body will actually hurt low to mid-range power. In other words Ford did not leave much if anything on the table when picking the correct throttle body. Where you will see the difference is on the blown motors.

I am not going the Accufab single blade route as I do not want to modify the intake, but I am trying to pick between the BBK 62mm or 65mm throttle body. I have a 1995 GT with a 70MM, and I've lost on the low end- and that brings me to the question, as my supercharger being a blow-through, it develops horsepower & torque higher in the revs...

Will I lose some power via lower air velocity on the low end with the 65MM throtte body vs. the 62? I have plenty of power up top, it is down low where I will need it with the gear swap.

THANKS!!! (Sorry so long).

Mike

[rich96cobra]

considering no one has responded, I will attempt. Considering a throttle body can be a bottle neck for your car, it should make a little difference on stock, 6-7 hp. Should make a big difference on a modified car. I am guessing 10-12 hp with a tune. This worrying about torque on top end, low end, the most your are going to gain with a bigger throttle body is 10-12

Here is what I have learned. Every time you make a significant change on your car, a tune is going to have to be done. I have put headers, and high flow cats, and I am going to put a high flow throttle body. Then I am going to dyno and use my sct programmer and tune.

Make sure you dyno (to see the actual difference) and tune whatever you decide. Because if you don't the 62 or 65 throttle body may not make a difference. matter fact, I say without the dyno or tune, you are not going make a difference.

here is an example. I thought by the seat of my pants I gain 12 hp with a sct program. I loaded the sct program and dynoed 255 wrhp with it. I then took the sct program off, dynoed 260 wrhp. I did not have it tuned properly. so, the seat of your pants is not going to tell you crap! Throwing crap on there and running around braggin is crap to. DYNO! Then you can talk smack!

Good luck,

Rich


Rich

[rich96cobra]

double posting, need to delete

[mustang_mike]

Thanks Rich! I would guess you are probably right, the dyno tune would make all the difference. Thanks for the help. Much appreciated. Mike