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SuperG
04-20-2006, 03:35 PM
Is it a bad thing to run the engine past 6800 rpm? Once the fuel issue was solved and the car ran like it was supposed to, my 1-2 and 2-3 shifts were at roughly 7200 rpm (I inadvertantly did that once more since but now avoided it) and felt like it could have gone higher. Perhaps the Superchip overrides the fuel cut-off?

My SHO's redline form the factory is 7500, but many people run the Yamaha engine to 8300 without issues, so I was wondering if the 4.6l Modular was simliar...

Thanks!

Firme
04-20-2006, 04:33 PM
The factory limiter is Fuel Shuttoff at 7k (which can be removed or raised with a chip or flash tuner if desired). The engine can take more, said to be run to 10k rpm on race specd motors, BUT the limiting factor on your stock engine would be your accessories (alternator especially) and your valve springs, which should hold fine to 7500 without floating the valve.

smashedheadcat
04-21-2006, 05:59 AM
I've taken my engine (forged, new stock valvetrain) up to 7800rpms under full boost a few times. I don't do it anymore, but I've done it with no ill effects. I feel that 6800rpms is a good place to start a powershift at. :thumbsup:

Blown96Snake
04-21-2006, 06:56 AM
What about powerband? I think my motor makes its peak rwhp at 6800-6900 rpms. Wouldn't you want to shift where the maximum horsepower is made? I'm now unsure and would like to know for myself...

Sweet looking white vert 97!

Dave

SuperG
04-21-2006, 08:17 AM
Thanks guys for the help and the props! Regarding when to shift, and I'm taking a WAG at this, is probably a function of when power begins to fall off vs. where in the power band the next shift is. With the blower, I was still feeling the pull at 7200 rpm's.

Pro-Dyno
04-25-2006, 10:23 PM
Have you put it on a dyno to see where the power band dropes 7200 sounds realy high to me we usualy see power drop at around 6200:)

SuperG
04-26-2006, 08:48 AM
Have you put it on a dyno to see where the power band dropes 7200 sounds realy high to me we usualy see power drop at around 6200:)
No, I have not yet, but it's on the list. I am still working out some other issues before I really push the car's get-up-and-go side. I will certainly get that done before I track it...

jackers
04-30-2006, 11:29 PM
I've taken my engine (forged, new stock valvetrain) up to 7800rpms under full boost a few times. I don't do it anymore, but I've done it with no ill effects. I feel that 6800rpms is a good place to start a powershift at. :thumbsup:

What would ever make you take your car that high Josh.....hehe

tcrews
05-01-2006, 06:09 PM
What about powerband? I think my motor makes its peak rwhp at 6800-6900 rpms. Wouldn't you want to shift where the maximum horsepower is made? I'm now unsure and would like to know for myself...

Sweet looking white vert 97!

DaveNever want to shift at or after peak power, you want to shift so that you remain "in" the powerband between the two gears (what you are in and what you are going to). With the gearing of the stock T-45 transmission that typically (on a stock or stockish engine) will be around 7200rpm 1st-2nd, 7000rpm 2nd-3rd and around 6800rpm 3rd-4th. This keeps you in your powerband through all the gears. Remember....if you hit peak and then shift....what are you making then? You want to pass peak so that your rpms drop into the powerband when you go to the next gear.
(edit) Since fuel shutoff is at 7,000rpm....just shift at 7,000rpm and you'll be fine.