4.6: ok to rev?
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From: Rocklin, CA
4.6: ok to rev?
i have heard that the 4.6 is one of the most reliable motors out there. i have about 80,000 miles on mine(2002), i just recieved my tunes from troyer. so far i have only used the 87 Tow, definetly a big difference, but anyway it definetly likes to rev. my question is it ok to rev the 4.6 really high? i trust TP, but my dad and i are just wondering if the 4.6 is built for it? thanks, brian
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mxr181,
It is common for Mustang guys to rev their 4.6 motors over 6000 RPM without problem. The real limiting factor for our engines is the torque converter. If you have an automatic then the torque converter is really not made to rev much above 5400 rpm without an anti-ballooning plate and special construction (brazing). Our cams are just about out of juice at that rpm anyway so no problem.
I think if you check your tach you will find you safe as Mike is quite aware of this limit.
It is common for Mustang guys to rev their 4.6 motors over 6000 RPM without problem. The real limiting factor for our engines is the torque converter. If you have an automatic then the torque converter is really not made to rev much above 5400 rpm without an anti-ballooning plate and special construction (brazing). Our cams are just about out of juice at that rpm anyway so no problem.
I think if you check your tach you will find you safe as Mike is quite aware of this limit.
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From: The LBC (Long Beach, CA)
Originally Posted by Zaairman
My 4.6 has 115K on it and sees 5000RPM just about every time I've driven it. Even a few times towing my boat. These motors love to rev.
So long as you don't OVER rev it.
My shift points are at around 5200rpm, I see this rpm almost every time I drive my Expy...and I've got 133K miles and a supercharger.
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From: Virginia
Hi Brian,
Your tunes are safe for that 4.6 engine.
What has to be remembered is that on the stock factory program, a lot of those trucks shift way too low for good performance, while others are fairly close to where they need to be - they vary quite a bit in this regard based on not only on which engine and what model year, but also on which PCM code each vehicle has - so some of them get increased (over stock) more or less than others, as we want to end up roughly about the same for the non-PI motors, and then at about the same for the PI motors, etc., for a given configuration.
The key is to stay within the limits of what the powertrain can take.
Now in terms of the truck 4.6 motor itself, it can be spun to 6500 rpm and live - though I wouldn't recommend it, and, it's not going to make good power up there *that* high. With the truck cams, it will peak it's power at about 5000-5200 rpm or so with a good intake & exhaust on there (and the WOT upshift points should be a few hundred rpm higher in most cases). The automatic transmission is the first limiting point, and as we have posted here many times over the years, we don't like to see the stock factory torque converter twisted much beyond about 5400-5500 rpm on a routine basis - now it can take the occasional dyno pull to 5800 rpm or so, but you don't want it to twist much over about 5400-5500 rpm on a frequent basis.
BTW, our towing tunes use a slightly lower WOT upshift point due to the heavier load being put on the motor, as is appropriate, compared to our "performance" tunes. Another point is, you can't always depend on the factory tach being particularly accurate - they range anywhere from fairly close to being hundreds of rpm off one way or the other, particularly when accelerating, that's just the nature of factory electronic tachs.
And don't forget, you still *always* have the protection of the rev limiter, we do not remove that - so the engine is not going to be able to turn more rpms than it can tolerate, there is always that "safety valve," so to speak. Additionally, YOU control the shift points by how much throttle you give it - if you do not want to turn as many rpms, then pull your foot out of the throttle - see, the shift points get higher with increased throttle, just like they do from the factory. Again, some get raised more or less than others, it all depends on what we are starting with and how the vehicle is configured.
The bottom line is, we're not spinning that powertrain to levels that it cannot take - as long as your truck is in good mechanical condition and has been properly maintained, our tunes are not going to hurt it.
Your tunes are safe for that 4.6 engine.
What has to be remembered is that on the stock factory program, a lot of those trucks shift way too low for good performance, while others are fairly close to where they need to be - they vary quite a bit in this regard based on not only on which engine and what model year, but also on which PCM code each vehicle has - so some of them get increased (over stock) more or less than others, as we want to end up roughly about the same for the non-PI motors, and then at about the same for the PI motors, etc., for a given configuration.
The key is to stay within the limits of what the powertrain can take.
Now in terms of the truck 4.6 motor itself, it can be spun to 6500 rpm and live - though I wouldn't recommend it, and, it's not going to make good power up there *that* high. With the truck cams, it will peak it's power at about 5000-5200 rpm or so with a good intake & exhaust on there (and the WOT upshift points should be a few hundred rpm higher in most cases). The automatic transmission is the first limiting point, and as we have posted here many times over the years, we don't like to see the stock factory torque converter twisted much beyond about 5400-5500 rpm on a routine basis - now it can take the occasional dyno pull to 5800 rpm or so, but you don't want it to twist much over about 5400-5500 rpm on a frequent basis.
BTW, our towing tunes use a slightly lower WOT upshift point due to the heavier load being put on the motor, as is appropriate, compared to our "performance" tunes. Another point is, you can't always depend on the factory tach being particularly accurate - they range anywhere from fairly close to being hundreds of rpm off one way or the other, particularly when accelerating, that's just the nature of factory electronic tachs.
And don't forget, you still *always* have the protection of the rev limiter, we do not remove that - so the engine is not going to be able to turn more rpms than it can tolerate, there is always that "safety valve," so to speak. Additionally, YOU control the shift points by how much throttle you give it - if you do not want to turn as many rpms, then pull your foot out of the throttle - see, the shift points get higher with increased throttle, just like they do from the factory. Again, some get raised more or less than others, it all depends on what we are starting with and how the vehicle is configured.
The bottom line is, we're not spinning that powertrain to levels that it cannot take - as long as your truck is in good mechanical condition and has been properly maintained, our tunes are not going to hurt it.