(4.6L newb) rev limiter

The rev limiter is at the same rpm everytime. It's just first gear is reving so fast that there is a lag in the needle to when the rev limiter hits. I had the same problem in a 03 viper.

Bmfhp said:

Ok Twisted, your answer seems logical enough. And what it is what I was afraid of because I don't want to get an aftermarket tach to monitor the motor but oh well. This is the 4.6L newb part here-What is the factory rev limiter? should it be in the 5900 range or the 6200 range?

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Unless they changed it in other years, 99 was 6050

Bmfhp said:

I have had a few mustangs in the past but this is my first long term experience with a 4.6L (the '97 last me 6 weeks before I got rid of it) When i am running I notice the rev limit on the 1-2 shift comes on at just after 6K (assumed its the 6250 limit) But on the 2-3 shift it comes on at just shy of 6K (assume 5900). I haven't tried it in 3rd to see what the rev limit is there yet. Is this normal or should it be one rev limit for all gears. (Manual trans) Bought the car used and I cannot see anyplace where it has been modified. This short limits has happened everytime under different weather conditions, regardless if the engine is hot or cold. It happens when I have it floor in a race or if I'm just giving it enough gas to hit the limiter in that gear (2nd). Any thoughts... thanks for the help

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Don't you think bouncing off the rev limiter so much would not be too good? Max horsepower is down around ~5300-5500 (unless you have your chip tuned for some serious goodies)

Just my $.02

it's probably not that good for it to hit the limiter just because the engine is shutting something off like fuel and your probably leaning out or soemthing. Maybe thats only a concern in boosted cars..

Im pretty sure its cutting the ignition rather than your fuel. Cutting the fuel would lead to some problems. Perhaps someone could confirm that it is the ignition?

Yeah I know it was cuting something off, I just wasn't sure what.

rev limiter is fuel cut. some of the power adder guys have switched to a spark cut type limiter because of this. And as stated before, I know for a fact that in 99 it was 6050. I don't know about other years.

My '98GT is 6000

speedfreak98r said:

My '98GT is 6000

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Are you going by what is in the binary file or what you see on your tach? The 6050 I got was out of the EEC.

jstreet0204 said:

rev limiter is fuel cut. some of the power adder guys have switched to a spark cut type limiter because of this. And as stated before, I know for a fact that in 99 it was 6050. I don't know about other years.

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That's a good bit of information that I didn't know. Now that I'm putting on my SC in a couple weeks I need to see about that. Where would you change how your limiter reacts?

Btw, my limiter seems to be at 6100 but that's a visual from the tach.

You shouldn't have to worry about the rev limiter because if you are winding the motor up that high in a race you are just wasting hp and time. When my car was dynoed it peaked out around 5100-5500. After that the hp is falling fast.

loosescrew79 said:

You shouldn't have to worry about the rev limiter because if you are winding the motor up that high in a race you are just wasting hp and time. When my car was dynoed it peaked out around 5100-5500. After that the hp is falling fast.

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You do not shift at peak power to make the best times. You want to maximize power across the shift range. Shifting at peak will drop you lower in the power band at the beginning of the next shift. Here are some shift point calulations using my old dyno numbers before the supercharger. So with peak numbers close to 5000 optimal shift points are close to 6000 and close to the rev limiter.
Optimum Shift Calculator by Bowling and Grippo
Input Parameters Are the Following:
Transmission Ratio One = 3.37 to 1
Transmission Ratio Two = 1.99 to 1
Transmission Ratio Three = 1.33 to 1
Transmission Ratio Four = 1.00 to 1
Horsepower = 100 at 2000 RPM
Horsepower = 130 at 2500 RPM
Horsepower = 150 at 3000 RPM
Horsepower = 200 at 3500 RPM
Horsepower = 240 at 4000 RPM
Horsepower = 260 at 4500 RPM
Horsepower = 270 at 5000 RPM
Horsepower = 265 at 5500 RPM
Horsepower = 220 at 6000 RPM
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Computation Results
Using the Criterion for Maintaining the Same Horsepower Before and After Shift:
Finding Best Shift Placement Points For Ratio 3.37 to 1.99: Error: Search outside range - need more RPM range in HP table! Finding Best Shift Placement Points For Ratio 1.99 to 1.33:
Found optimum shift RPM at 5882, which achieves 236 horsepower and lowers the RPM To 3931 after shift
Finding Best Shift Placement Points For Ratio 1.33 to 1.00:
Found optimum shift RPM at 5702, which achieves 253 horsepower and lowers the RPM To 4288 after shift

--------------------------------------------------------------------------------
Maximizing the Area Under the Horsepower Curve:
Finding Best Shift Placement Points For Ratio 3.37 to 1.99:
Found optimum shift RPM at 5995, which achieves maximum area under horsepower curve, and lowers the RPM to 3540 after shift
Finding Best Shift Placement Points For Ratio 1.99 to 1.33:
Found optimum shift RPM at 6000, which achieves maximum area under horsepower curve, and lowers the RPM to 4010 after shift
Finding Best Shift Placement Points For Ratio 1.33 to 1.00:
Found optimum shift RPM at 5998, which achieves maximum area under horsepower curve, and lowers the RPM to 4510 after shift

GDawg said:

That's a good bit of information that I didn't know. Now that I'm putting on my SC in a couple weeks I need to see about that. Where would you change how your limiter reacts?

Btw, my limiter seems to be at 6100 but that's a visual from the tach.

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If you are seeing it on the tach It is probably 6050. To change to a spark type limiter you have to buy something like an MSD unit. But there is a big debate as to whether the fuel cut limiter will do any harm. Some say since it creates a "No Fuel" condition instead of a lean condition, it doesn't hurt anything. Others just don't trust it. I have hit mine several times with the supercharger and have had no problems.

Just to back up what Jstreet is saying, the rev limiter on my car was 6050 stock.

I wish the limiter pulled spark instead of fuel, but oh well. Hit the rev limiter once on spray and my intake is toast.

jstreet0204 said:

Are you going by what is in the binary file or what you see on your tach? The 6050 I got was out of the EEC.

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I'm goin by the facts biotch.



j/k. I dont remember where that number came from, but it seems to cut out exactly at 6k.