# cant go past 158 mph



## 740tank (Mar 23, 2009)

before all the mods it wont go faster than 158 mph then after some mods cam, exhuast manfolds 85 mm throttle body intake manifold and had it tuned after all that it still wont let me accelerate past 158 mph i get there in 5th when I hit 6th it just stays there any suggestions


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## jpalamar (Jul 22, 2008)

It take alot to go much faster. Once you hit high speeds, your talking exponential amounts of power and proper gearing. Oh, and my car feels very squiggly at that speed, I won't do it again without some suspension mods.


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## CChase (Dec 11, 2007)

Isn't the limiter somewhere around there? Or am I silly to not assume you had it raised. I feel like I have read people with stock cars with the limiter upped going past that speed.


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## jpalamar (Jul 22, 2008)

CChase said:


> Isn't the limiter somewhere around there? Or am I silly to not assume you had it raised. I feel like I have read people with stock cars with the limiter upped going past that speed.


He has a cam, so he is tuned. I would assume that the top speed limiter was disabled.


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## Rukee (Feb 8, 2007)

I bet it gets to 158 faster then it did before.


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## 740tank (Mar 23, 2009)

oh yeah it gets there alot faster but at 158 the rev limiter kicks in in 5th gear forcing me to shift but have no acceleration in 6th gear it just stays at 157 lost 1 mph when I shift


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## Rukee (Feb 8, 2007)

Maybe the tuner just forgot to dissable the speed limiter? Give them a call.


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## 6QTS11OZ (Mar 27, 2005)

Rukee said:


> Maybe the tuner just forgot to dissable the speed limiter? Give them a call.


The tuners won't raise the top speed limiter unless you ask them too. Their job is solely to optimize your engine's performance. I asked to have mine raise and the tuner set it at 205 mph.


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## Mark1si (Sep 8, 2009)

I found this.... More interesting to the racer is the fact that it takes 145 hp to overcome drag at 150 mph. We know that our Corvette example car has about 240 hp, so about 95 hp must be going into overcoming rolling resistance and the slight braking forces arising from internal friction in the drive train and wheel bearings. Race cars capable of going 200 mph usually have at least 650 hp, about 350 of which goes into overcoming air resistance. It is probably possible to go 200 mph with a car in the 450-500 hp range, but such a car would have very good aerodynamics; expensive, low-friction internal parts; and low rolling resistance tires, which are designed to have the smallest possible contact patch like high performance bicycle tires, and are therefore not good for handling.


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## Poncho Dan (Jun 30, 2009)

My Grand Am only has 140hp, and I topped that out at about 112 (pure LULZ to the GTO owner). And honestly, I haven't had the room to do better than 135 in the GTO... either that or the roads are just too damn lumpy.


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## 740tank (Mar 23, 2009)

I pretty much have about 10 miles of straight new paved road with very little intersections must be lucky lol


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## AlaGreyGoat (Jul 6, 2006)

What gear do you have?
On stock diameter tires you should be doing 176 MPH
at 6700 RPM limit in 5th gear.
I've only been to 155 MPH when I had to let off, but was still pulling strong.
It has been tuned with the speed limiter set to 210 MPH and the RPM limit at stock 6700 RPM.

Larry


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## GM4life (Mar 18, 2007)

740tank said:


> oh yeah it gets there alot faster but at 158 the rev limiter kicks in in 5th gear forcing me to shift but have no acceleration in 6th gear it just stays at 157 lost 1 mph when I shift


Just like 6QTS said, your tuner didn't raise the top speed limiter. You will not reach top speed in 6th because it is not accel gear too steep of a gear. Top speed is only reached in 5th.


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