optimum shift point for stock 4.6 SOHC ?

Just curious, what might be considered the optimum shift point on stock late model 4.6 SOHC GT cars (when trying to accelerate as fast as possible) ? Also, at what rpm does the factory rev limiter start to shut things down? There is no mention in the Mustang owner's manual as to what the rev "limit" is. My tach has a red mark that begins somewhere a little after 5,500 rpm, so I would guess this is an indicator that 5,500 rpm is the "redline". Ford rates this engine at 260 hp at 5250 rpm, so in theory, you'd need to shift at a point past that to take advantage of the peak horsepower. So... in sum, where does everyone like to shift?

Reply to
GT-Vert-03
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To find out where the rev limiter is set just run it out in first until it shuts down. My '94 shuts down at about 5200. IIRC this was set by Ford to deal with the stock torque converter "ballooning" issue and may still apply in the current models.There is a product from Baumann Engineering called the Baumannator TCS Electronic Transmission Control System which can handle the shift point and other enhancements.

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Reply to
Richard

I have a 98 GT (4.6 SOHC) and I shift at around 5800-6000 RPMs. Btw.. you didn't specify a year (original post) so I'm assuming you meant the 2003's were rated 260hp. Mine is only rated 225hp... and that doesn't mean touching the ground.

-Mike

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Reply to
memsetpc

Unless you've done a headswap, you're wasting time reving it that high. Power dies off quickly after about ~5,000 RPMs. Shifting earlier would benefit you.

Reply to
Keith

You're not gaining anything by taking the GT to redline before you shift. The 2V heads, even though "improved" on the 1999+ models, don't flow worth a damn that high into the RPM range.

I'd shift out around 4500 rpm and avoid the performance hit that comes with winding it so far up out of the powerband.

Just my $0.02 worth

Reply to
Tungsten

It really doesn't help much after the headswap either. ;-)

Reply to
Tungsten

Hm... didn't know that. I'll start shifting around 5300rpms & see if I notice anything. Thanks! =).

-Mike

Reply to
memsetpc

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Interesting. I see that Ford rates the late model 4.6 SOHC engine at 260 hp at 5,250 rpm. If this is correct, then you'd think that the optimum shift pint would be at least a few hundred rpm above that, for instance 5,500 rpm. However, I did see a horsepower / torque curve chart on the web somewhere for the 4.6 SOHC, and while it showed peak torque at around 4,000 rpm, (as advertised by Ford), it also showed what appeared to be peak hp occurring somewhere around 4,600 rpm, and then dropping off by 5,000 rpm (earlier than advertised by Ford)... and the pull was ended by 5,200 rpm or so. I wonder what gives? I still haven't brought mine up past 5,000 rpm yet, but I did bring it up to a bit over 4,000 rpm the other day under WOT. I have to admit, I am not overly impressed with the performance of this car. This is why I have been looking more and more into various mods that can be done to increase performance. The car certainly looks faster than it is. I see now why many people get a GT and then not too long after wind up trading it in for a Mach 1 or Cobra. I think my GT is a fine car, it handles amazingly well, is smooth, quiet, etc, but when it comes to having balls-out power, it comes up short. Well, I'm stuck with it now for a while, so I'll need to make the best of it... the vert top is a lot of fun anyway. And this is probably one of the best handling cars I have ever driven. I know a lot of people out there claim that you need to do a bunch of mods to make the GT handle well, and I CAN feel the various "weaknesses" in the handling of my GT that I read about on the web, but having said that, the car STILL handles amazingly well in stock form in my opinion. Certainly the best mating of handling verses a smooth ride anyway. It goes where you point it with zero fuss and perfect accuracy at about as fast as you can make it go. Well, while the car itself is kinda slow, it is faster than many other 4 seater verts out there for the money, so I guess I can't complain. I see cars out there that are faster, but many of them are at least $20k - $40k MORE than a GT (or they are only 2-seaters which is no good in my book). Well, a GT is a good deal no matter how you slice it... a stock GT is probably more than fast enough for just about anyone other than a serious performance enthusiast... I have to admit, I did expect the car to be faster and I wish it was, but it's still fun to drive. Finally, I must remind myself, how fast can you go on the street anyway without getting killed or arrested? There comes a point where too much power is simply not useable, unless you do plan to bring the car to the track (which I unfortunately no longer have the time to do.) I hate to sound like an old man, but too much speed can get you into trouble. At least this type of thinking will help keep me from being unsatisfied with my GT.

Reply to
GT-Vert-03

I have to disagree. Short shifting will definitely hurt you in a '99+. The engine will pull hard to redline, at least after opening up the exhaust side. I'm not sure where the optimal shift point is but I know it's between

5700 and 6000 rpms. I've never been in a '99+ with stock exhaust, so maybe that's what you're comparing it too. I have a friend with a '98 that's headswapped with Steen P&P'd heads and oversize valves, and it pretty much otherwise identical to mine (my 4.10s vs his 3.73s, and he's naturally got higher compression). It pulls *a little harder* up top and similar to mine below 5000 rpms. Here's a good discussion of shift points that may be of interest...
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And Tungsten...if you're looking for a good forum, the ModDepot is it. The Corral's really gone downhill lately (haven't seen you there in quite awhile anyway). It's turning into Stangnet, which is turning into Mustangworld. BTW...I'm PhatDoggy on those boards. ModDepot is really the only place I go anymore, since most of the people I talked with and have good knowledge are there.
Reply to
Keith

It may have been mine before the engine swap. I posted it a month or two back...

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4.10 gears, a timing adjuster (or better yet a dyno-tuned chip - Fordchips or JMS - which will also take care of your trans and speedo issues after the gear swap), and a high flow catted X or H pipe with a good sounding catback will make alot of difference. Of course, most of those will cause warranty headaches, but now you've got something to save the pennies for. :-)
Reply to
Keith

Tungsten, I must disagree. If I shifted like that, I would have only

1000 usable rpms with which to play. I know my engine doesn't wake up until about 3200 rpm, and it pulls quite well to the redline.

The shift points you're describing sound very 5.0-ish.

Reply to
Victor DiMichina

I also disagree. A 99 and up GT, I'm guessing would need at least

5,500 rpms. 4,500 is way too low.

Sorry. The hot shift points for a stock 5.0 with 3.08s is 5,500,

5,500, and then 5,000.

Patrick '93 Cobra Previous '87 LX 5.0 ran 14.2 @ 98 mph

Reply to
Patrick

No problem. It's been a good ten years since I've driven a 5.0. Even then it wasn't mine. All I remember about it was gobs and gobs of bottom end torque. I know I have to treat my engine differently to get the results I want.

Vic

2kGT 5m blk suspension upgrades
Reply to
Victor DiMichina

Thanks for the invite... I'll be sure to register over there.

Reply to
Tungsten

Weird... but then again, there's a boatload wrong with my car right now so my opinions of the flow-rate of the PI heads may be a bit skewed.

Reply to
Tungsten

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