Main Bearing Durability Under Boost

[rhyrlik]

Has anyone here torn down a supercharged GT motor? How do the main bearings hold-up under boost?

I'm debating the purchase of a Cobra crank because I plan on spinning it to 6500 RPM and am concerned about crankshaft flex and bearing failure.

Thanks,

Ralph

 

[jstreet0204]

Just curious, but what is your reasoning for spinning the motor so high?

 

[rhyrlik]

The my new cams will shift the powerband past 6000 RPM.

 

[crew_dawg16]

you should probably get a forged crank if you are going to exceed the stock redline on a regular basis. I know the GT crank is good for 700 hp or so, but rpms are what's hard on cranks/bearings.

 

[rhyrlik]

I'm just wondering if there is any evidence of flexing or warpage with the GT crank while under boost.

I trust the crank won't snap in two, but I also want my engine to last more than a year.

 

[GinoGT]

If the crank is properly prepped, it should hold up. KenB is showing the world what's up with GT cranks in his car: 7000+RPMs and going strong.

The cast GT crank is lighter than the forged Cobra one. Now if you're going to make stupid amounts of power, than the forged would be worth it.

 

[03trubluGT]

I'm just wondering if there is any evidence of flexing or warpage with the GT crank while under boost.

I trust the crank won't snap in two, but I also want my engine to last more than a year.

A friend of mine is putting out about 380 HP in his Vortech-ed Bullitt. He's had it over a year and 20k miles.

I have about 5500 miles on my GT. See sig for power levels. What kind of KB kit do you have? Did you get those numbers from a Mustang Dyno?

Matt

 

[rhyrlik]

I have the 6LB NIC kit.

I want to shift at 6100 RPM, but want that 6500 RPM cushion. I don't want a forged crank because that will require clearancing of the block. I basically want to spend $1000 and drop forged rods and pistons in it, and not have to worry about anything. I don't want mega power, just extra RPM to avoid shifting near the end of the 1/4 mile mark.

 

[03trubluGT]

I have the 6LB NIC kit.

I want to shift at 6100 RPM, but want that 6500 RPM cushion. I don't want a forged crank because that will require clearancing of the block. I basically want to spend $1000 and drop forged rods and pistons in it, and not have to worry about anything. I don't want mega power, just extra RPM to avoid shifting near the end of the 1/4 mile mark.

I'd call Ken B at Modular Depot www.modulardepot.com get the shop's number off the the home page and give him a call or PM.

Matt