Top speed
Top speed
I searched and didn't see anything, so i am asking. If i were to go on a really big strait away what is the top speed of a sr20det? And since i know it will depends on mods, just assume its stock. I know greddy has a speed cut eliminator for like 80 bucks. How much faster would the car be able to go?
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themadscientist
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SpeedRacer1
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Well mine cuts out at about 125-130, and you dont need a huge stretch to get it that fast;). The only bad thing is that the governer kicks in at 5000(ish)RPM's in 5th gear for me. This means that if you buy a speed defencer you only have about 2500RPM's left after 130 before the engine is redlining.
2500 rpm left doing 130 would probably get me to like 140-150 ish. Im thinking that will be cool as hell. ThanksSpeedRacer1 wrote:Well mine cuts out at about 125-130, and you dont need a huge stretch to get it that fast;). The only bad thing is that the governer kicks in at 5000(ish)RPM's in 5th gear for me. This means that if you buy a speed defencer you only have about 2500RPM's left after 130 before the engine is redlining.
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themadscientist
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that sounds a little slow, i thought more like 155mph. you can get a 300zx tt diff and go faster. they are 3.8????i can't remember. another thought, my old ka 5 speed was geared taller. i was at like 3000 rpm at 70mph. the sr gears are shorter and i'm at about 3500 rpm at 70mph. do both mods and get about 185? higher?shaun
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Cyberkreig
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Cyberkreig
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TheProfessional
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cyberkreig... agreed. the sr20 has completely different characteristics than the KA, therefore, the trannies could be identical (which they practically are) and can have different top speed as well as different RPMS at MPH. bp2000, do you plan on going over 130 or something? if you get caught, remember the best invention of the 20th century... "soap on a rope."
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Onizuka
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pampadori wrote:no. they aren't. 5th gear is taller on a ka. why does everyone always say that? at 60mph in ka i was just under 3000rpm. in both of my sr's, i'm at 3500rpm. so, NO.shaun
he was refering to the fact that gears can be swaped between the two.
BTW, that is strange because im at 70 at about 3050 on my ka
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SpeedRacer1
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Onizuka
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pampadori wrote:woo! i wish my sr was at 3050 at 70mph. i'm thinking about getting a speed sensor and lsd from a tt 300zx. they have a good rear end ratio for higher speed driving. shaun
This might mess up things for daily driving in low gears.. just get a KA fifth gear and swap it in.
EDIT: i was refering to the fact that a 300zx TT lsd will mess up your final drive.
Power and torque have nothing to do with it. If the gear ratios were exactly the same, the diff ratio was exactly the same, and the wheels/tires were exactly the same, both engines would be running the same speed at the same rpm in the same gear. So if a KA transmission has the same ratios as a SR transmission (which I have no clue about) then they will both be at 'x' speed at 'y' rpm in 'z' gear . They can have different top speeds though, only because they have different power/torque levels.
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Cyberkreig
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SpeedRacer1 wrote:Well according to my Speedo and Tach my SR runs like this:65MPH = 3000RPM70MPH = 3300RPM75MPH = 3500RPM80MPH = 3750RPM85MPH = 4000RPM
that isn't what mine is at. i have a early redtop. i am using a 300zx na diff, and the ka speed sensor. any idea why mine is different? btw, the speedsensor takes its reading from the tail shaft, so tire sizes won't effect what my speed says. only "actual" speed. so why am i off? fwiw, my friends sentra is the same as i am at 60mph.shaun
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Onizuka
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Dori Dori wrote:Power and torque have nothing to do with it. If the gear ratios were exactly the same, the diff ratio was exactly the same, and the wheels/tires were exactly the same, both engines would be running the same speed at the same rpm in the same gear. So if a KA transmission has the same ratios as a SR transmission (which I have no clue about) then they will both be at 'x' speed at 'y' rpm in 'z' gear . They can have different top speeds though, only because they have different power/torque levels.
What you say is all true but top speed is determind by gears and only gears. For example, assume you have a KA and SR (with identicle transmission's) driving on the same surface that is perfectly level and wind is perfectly still. both will reach the same maximum speed (assuming they have the same redline) but the only difforence is that the more powerful car will get there quicker, assuming the two are aerodynamicly identicle.
Anybody actually try and throw the math at this cause I did and it was a pretty high top speed math wise with the gears and 225/50R-16 tires. I was getting to about 170, granted there is alot more then that going on when you actuall get going that high to be able to say that she'll top out at 170-James
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Th*GgEd_OuTtTt
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J-Spec Tuner, Top speed is not, I repeat, IS NOT only determined by gearing. You are wrong, wrong, WRONG; and I hope nobody buys into that load of B S. There are 3 main factors that determine a cars top speed. Gearing, drag, and POWER (hp that is). Why do you think that top speed cars have insane power? To overcome drag. In your scenario of every other factor remaining constant, the more powerful car will have the higher top speed. Period.
Go here to find out why:http://www.perry-lake.k12.oh.u....html
If you read it and understand it, you'll know that you will need roughly 23% more power for a 10mph increase in top speed. Given the power of a stock KA (155hp) and the power of a stock red top SR (205); the SR has a power increase of roughly 32%. That means it could go around 15mph faster...all other variables remaining constant (assuming that gearing and redline allow and that the car's top speeds are drag limited).
Also, unless you are measuring with GPS, your top speed read outs are flawed b/c your speedo becomes very unreliable after 90-100mph. Chances are you are not really going that fast.
Go here to find out why:http://www.perry-lake.k12.oh.u....html
If you read it and understand it, you'll know that you will need roughly 23% more power for a 10mph increase in top speed. Given the power of a stock KA (155hp) and the power of a stock red top SR (205); the SR has a power increase of roughly 32%. That means it could go around 15mph faster...all other variables remaining constant (assuming that gearing and redline allow and that the car's top speeds are drag limited).
Also, unless you are measuring with GPS, your top speed read outs are flawed b/c your speedo becomes very unreliable after 90-100mph. Chances are you are not really going that fast.