130mphs

[MikeyP]

How fast did Car and Driver clock their P5 when they tested it? I don't think they got theirs going much over 113. I think the speedo is a wee bit off. (Sorry, but I trust the car mags over my over speedo!)

Anyhoo, while we're on the topic could someone clear something up for me?
Assuming you're running the same gearing, in my mind it doesn't matter if you have 130hp or 1300hp (and the same redline) you will have the same top speed..?

If the redline of a P5 is 6500, 1/2 of that is 3250. When you're revving at 3250 in 5th (~110km/hr), theoretically if it would pull to redline (double the rpm) in 5th gear you would be going double the speed (~220km/hr).

Am I correct in assuming this? I mean gear ratios and such are just math, right?
HELP!

 

[Pro5OnSpeed]

not necessarily. you have to remember HP at specific rpm. and the stock engine's power band starts to drop down just after 5500. thats why when they rate HP they rate it at peak rpm, and at that peak is when you find the highest power band. thats why when you are at almost redline, you lose a slight bit of horsepower.

now when you modify the engine, of course it changes. but the engine is only half of it. you could regear your transmission in order to compensate for the torque curve, that would give you a better gear ratio. have you ever played Gran Tursimo?

but there are also other things that come into play, tire grip, aerodynamics, suspension.

and you could have a 1300HP engine, but only get it to do 130 because of the tranny. another example, lb ft of torque is different from bhp. like a turbo diesel on a semi truck. those things have over 500HP, but with the tranny, have over 600 lb ft of torque in certain gears. lb ft is determined by how much torque is created by lifting 550lbs one foot one second, and bhp is determined by a load on the engine at specific rpms, ie. a dyno.

does that help?

 

[LinuxRacr]

How fast did Car and Driver clock their P5 when they tested it? I don't think they got theirs going much over 113. I think the speedo is a wee bit off. (Sorry, but I trust the car mags over my over speedo!)

The car that Car and Driver probably wasn't broken in yet, so it wouldn't get higher.

 

[MikeyP]

Pro5OnSpeed: Thx for the reply!... but I'm still a wee bit confused. I'm just talking about gearing and such. ie: If we could bolt a Ferrari V8 to our tranny, using all the same ratios, etc, would it not have the same speed at 6,500 rpm as a stock Protege (due to all the gear ratios, etc)..?

LinuxRacr: Thx for your reply too!.. but do you think a broken in Protege5 will gain an extra ~17mph just by being broken in? I mean that's a heckuva lot of horsies missing when we're talking a stock ~130ish.

 

[colin949]

wheres spoolin he should know about this becauce his car is the fastest

 

[Pro5OnSpeed]

not really........

let say for arguemnet that we strap a ferrari v-8 onto the pro5 tranny. the way our tranny's are, they arent geared to handle the massive amounts of torque generated by that engine. the reason for this is size, and ratio.

if you use the same ratio, remember that the v-8 is cranking out way more torque and HP for the tranny to handle. and you will get to the speeds quicker since you have more HP. in essence in first gear you may get to 90mph at a higher rpm then what "normal" rpm is for that tranny. see what i mean? you get through gears quicker at higher speeds then normal. but sometimes the tranny's cant take the torque. remember torque is turning force.

now the v-8 pumping that much torque into our tranny would definately blow it, becuase they could only handle so much torque. materials, ratios and machining have alot to do with that. its kinda hard to explain.

best way to learn it is to get a book, or buy GranTurismo for PS2, its a little on the fantasy side but all the concepts are the same, and regear the cars you tune. HP at RPM, that is what you have to look for, those are the numbers you should be concerned with.

 

[BluMp3Turbo]

no way man the governor kicks in at exactly 137 mph no one... on less u have reprogrammed ur ecu and a different tranny (like maybe a 6th gear) will u hit past 140 mph. 137 mph ur rpms should be at 6700 thats almost on redline (i think). The most i ever went was 137 mph at 6700 rpms (when my rev limiter shut off) racing a brand new altima 3.5 on the highway he was bearly keeping up w/ me, and a v-8 engine on our protege trannies haha after u try it and run it a couple of times all u'll have is metal shaving coming out of the tranny instead of gears.

 

[MikeyP]

*sigh*... Did I say hypothetical? My point was to find out more about ratios.. if all ratios stay the same (no matter what the engine, no matter if the tranny could handle it or not. For fun let's just say it can, ok?), x rpms would = y mph/kms/hr no matter what engine you bolt to the tranny.
Know what I mean?

For arguments sake let's take stock P5, strap a turbo onto it. You're still revving at ~3250rpm at ~65mph right? A turbo doesn't magically drop rpms does it?

 

[Pro5OnSpeed]

a turbo increases your torque. and it will give you more horsepower. you will have an increase of speed much quicker because of the horsepower gain.

for example....

ken and i went down the highway one time. his car is a turboed P5, and he has much more HP then i do. it took him less time to get to 130 then it did i. i topped out at 130 but since he has more HP he can increase his speed. in a matter of speaking we may be at the same rpm, but he is going faster because of the increase in torque compared to mine. HP at RPM..... i need a dyno chart. now you could gear a better transmission to give you more of a top speed so that you dont top out at 6500 in 5th gear. it all depends on how long you stay in a specific gear, and that mainly depends on your engine.

the ratios of gears determines how many teeth there are and to what size the ratio is from small gear to larger gear. a small diameter gear to a larger diameter gear will increase the torque, because it takes less effort for the smaller gear to turn the big one because of the circumfrence, there is more distance for the smaller gear to go. which can give you mad accelleration but bad top end.

adversly, if you took a larger gear to a smaller gear, the torque would be lower, because it takes more force to rotate it around the smaller circumfrence, and you get more revolutions this way. this is for top end, and this is why you cant start your car in 5th gear. the load is to much. this is why you need a set of gears to properly gradually increase your speed and use torque efficiently, throughout your power band.

think of it also like a bicycle changing gears. if you keep it in first gear all the time you arent using your full potential, and you will tire yourself out.

key things.... BHP determines your stock engine HP at the crank. lb ft determines torque at rpm range.

 

[TheHonzaP5]

Guys, a couple of points:

"no way man the governor kicks in at exactly 137 mph no one... "
- WE DO NOT HAVE GOVERNORS for the reason that our cars cannot go fast enough. Governors are there for the reason of tires, which cannot handle the high mph speed (but since our cars CANNOT go over 125, there's no threat - do not go off of your speedometer, it's off).

Next, what kind of bulls*** is that more torque or horsepower will make you go faster? Hey, we have the same redline, trannies etc. With more HP you can only ACHIEVE the top speed FASTER....more horsepower will not lower your rpms dughhhhhhhh. Sorry for my attitude, but this link is nuts, I mean, think about it!!!

 

[frady2001]

i agree with the honza on this one, as long as you have the same engine internals and ratios(ie: changing the engine crank speed) and the same tranny and gears, your speed to rpm ratio will stay the same. also i saw a little earlier people talking about going 130 and looking out for the hp. please educate me on how you look out for a hiding police car and react to it before the 1/4 of a second it takes a laser to get your speed. not trying to be a smartass, just wondering.

 

[BluMp3Turbo]

i agree w/ honza w/ a turbo u reach u maximum speed faster not add more speed... and ur right its not a governor chip its the actual computer that send a signal to ur rev limiter to cut off fuel
bara bing!

 

[BluMp3Turbo]

actually governor chips r used mostly on german cars (benz, bmw, audi, and porsches) its becuz in germany they have the ******* autobahn highway (sorry sp)
they pick up speeds of like 160 - 180 mph
i think! nastiness!!!!!!

 

[smp3000]

Finally got my Digicam today!! (2thumbs) So I decided to take a little drive and test the governer theories and transmission comments. Remembe rI am boosted and now running at about 8.3 psi.

Did I go any faster than this????? No... I got scared and slowed down to 65 (I was onthe freeway) before I even saw another pair of headlights behind or in front of me.

I do not suggest nor condone going this fast or even over the enforced MPH.

 

[Pro5OnSpeed]

i've been thinking to hard again. i just confuzzled myself. you are right, if we have same redline we will only be able to sustain longer i agree. but if you have more HP then stock you'll be able to accelerate to the top end more quickly.

 

[Pro5OnSpeed]

rememeber, you increase your HP you increase the redline, saying that we had no "governer"

 

[mp5]

To answer MikeyP's question, ratios do not change just because you make more hp. At any given rpm in any given gear your speed will always be the same regardless of the amount of hp you are generating at that time. For example going up hill at 70mph or going downhill at 70 mph. In both instances the rpms are the same, but you need more hp to go up then down.

However, in our cars more hp would equal a higher top speed. The reason is the fact that our cars do not have enough hp to actually reach redline in 5th gear due to the aerodynamic drag acting on our cars at those speeds.

Also, redline is not effected by hp. redline is determined mostly by what rpm the valvetrain can withstand before destroying itself (ie valve material, valve spring strength, retaing clips etc)and to a slightly less degree the strength of all the remaning rotating parts (cams, crank, connecting rods etc.)

 

[70]

There is some misinformation in this thread. The Protege does not have a speed govenor. The stock gearing will top out at about 142 mph given the 6500 rpm redline. The fuel cut off is some 7200 rpm I think.

The top speed of the car, subsequently barring any horsepower v drag related issues would then be ~142.

Adding horsepower in theory would give you more speed on the top end, if gearing was not the limiting factor. In the Protege, the drag is what limits the speed in stock trim. So, adding more horsepower would then allow you to reach the actual top speed that the gearing allows. Which, no matter what is going to be about 142 mph.

The only gear changes I've seen are those used in the Protege's in the World Challenge, and those only shorten the ratios making for a really tight box. Which, at the stock 6500 rpm redline would limit you to about 90 mph. Since the SWC cars spin up to 8000 rpm, they can get up to about 120.

 

[PA_MP3_Man]

But from the look of smp's picture he seems to be doing slightly over 140 mph at 6000 rpm's. So 150 doesn't really seem too impossible. 140 man that's crazy, the fastest I've ever went was 125 in my friends rsx type s. And I was shittin bricks doin that. How'd you manage to take a hand of the steering wheel and snap a picture. That definately takes some balls. And is that only 12,000 miles I see. Man, i got you doubled. Damn long ass commute to work any how.

 

[PA_MP3_Man]

I also heard that if your on the autobahn and you cause a wreck at high speeds, if you aren't dead, you go to jail. Just what I heard though, I could be wrong.