Top end speed run.

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timk225
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Top end speed run.

Post by timk225 » Sun Apr 28, 2013 1:46 pm

I took my 5 SXT ATX out for a top end speed run yesterday. It's all stock except for a 1st gen DOHC style muffler (Walker Quietflow 3), and the airbox resonator is removed, and a K&N filter in the stock airbox.

On a long flat piece of road, I made it up to 109 before having to get on the brakes, as some idiot was in my lane. But going from 100-109 took a good 1/4 mile. This thing has no top end at all! I wanted a 50 hp nitrous shot badly for that speed run.

It was running about 4300 rpm in top gear at 109, so it should have been in the power range, according to what I read on stock motors.

I have a Pacesetter header and new Magnaflow 2-1/2" cat to install next weekend, I hope it does better in a top end run after that.

A friend with a 3 SXT 5 speed said he had no problem hitting the 120 mph cutoff.

occasional demons
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Re: Top end speed run.

Post by occasional demons » Sun Apr 28, 2013 2:44 pm

timk225 wrote:
On a long flat piece of road, I made it up to 109 before having to get on the brakes, as some idiot was in my lane.

Most likely what the other person was thinking too.
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JeffM
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Post by JeffM » Sun Apr 28, 2013 5:10 pm

Just wondering, why are you shooting for the top end? The non-R/T PCM is limited to 118mph, and you'll have trouble hitting that even on a downhill. Improving a 9mph range that high up sounds a little silly and any mods to improve that would only hurt your low end.
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timk225
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Post by timk225 » Sun Apr 28, 2013 11:42 pm

Well I'm not going to build the car for top end only, I was just disappointed that it had so much trouble with top end acceleration. It was good to 80, ok to 90, and then it took a while to get to 100 and even longer to 109.

My 1989 2.5 Turbo 5 speed Spirit ES easily hit its 120 mph speed limiter and would have gone over 130 with no problem when it was intercooled and on 12 psi boost.

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Post by occasional demons » Mon Apr 29, 2013 12:02 am

Not really an apples to apples comparison there.

The 2.5 more than likely had a ton more torque, and no oil pump in the trans consuming power.

An MTX is going to get up to speed faster on that alone. That extra parasitic loss on an engine, that is at the end of it's power band, fighting wind resistance, is going to take a hit with something that even consumes as little as 5 hp.

Now on a vehicle that is an absolute brick, it may not matter, because the drag will kill either, before it gets to that point. Given both engines are equal.
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akirony
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Re: Top end speed run.

Post by akirony » Mon Apr 29, 2013 9:18 pm

occasional demons wrote:
timk225 wrote:
On a long flat piece of road, I made it up to 109 before having to get on the brakes, as some idiot was in my lane.

Most likely what the other person was thinking too.
:laughing3:
But seriously what are you expecting from an ATX economy car? Of course theres no top end :quotes: WHY because gas saving city car. Its only a 4spd too isnt it? 4spd+132hp+sxt pcm=slow car. Not trying to slam you or anything but these are basics you should know if you wanna go fast.
Have car-have car problems. Have srt4-have speed problems
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INVUJerry
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Post by INVUJerry » Wed May 15, 2013 6:03 am

My 5 speed 05 sxt could get to the cutoff reasonably well. That ATX is a parasite to any power. And why are you worried about going 100+?

timk225
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Post by timk225 » Thu May 16, 2013 11:49 pm

I don't plan to go over 100 mph every day, but it is a benchmark to measure modifications and improvements by.

0-75 multiple times a day is common for me.

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