well my car tops out at about 120 and i know that i can go alot faster than that because im only at 5500RPMS at 120MPH. and i have a p28 ECU in the car now if i get a P72 or something similar how much faster can i go?

 

what do you need to go over 120mph for? any tuning program installed on the ECU will remove the top end limiter, maybe you should go that route...

 

yea u need sumthin...120 is grandma speed

 

You can't go any faster because your car doesn't have enough power to overcome its own drag. Switching ECUs won't make you go faster, and if the ECU isn't the correct one for the engine you have, you will lose power because the tuning will be incorrect. Even getting tuned isn't going to make you go faster, as you probably won't notice small difference that a few HP will make when you reach the power to drag threshold.

Your car, which I'm going to assume is a SOHC VTEC (D16Z6 likely) is well known for a 120 speed limit based on drag and its low power to weight ratio. Don't feel bad, 120 MPH with only 128HP and the aerodynamics of an economy car isn't that bad.

If you want to go faster than that, you better start planning on making a lot more power, because the drag force goes up with the square of your velocity. To get the full picture, drag force = (coefficient of drag)*(frontal area)*(velocity^2)*(1/2)*(density of air), so then you can see what the drag does with speed.

JDM ECUs have a 112 MPH speed limiter. USDM ECUs have a 158MPH speed limiter. I would assume you have a USDM P28, because the JDM SOHC imports are rare and any Honda engine imports from Europe and Australia really uncommon. So you have the 158MPH speed limiter.

So now I'm going to be the asshole. You shouldn't be going 120 on public roads, and you sure as fuck shouldn't be stupid enough to post about it on a public forum. You're an idiot.

 

Ok, so now the rest of the story that you haven't actually said anything about:

I see on your profile that you have a GSR engine. Sort of an important detail to omit when looking for help, don't you think? So, you're running that engine with a stock P28? Awesome.

You'll pick up some HP with the correct ECU, because you're using a completely incorrect tune for that engine. So you haven't been very kind to that engine. You should really get a P72 just so it runs safely and nothing else, because the extra power isn't going to be enough to add more than a few more MPH max if you're topping out at 120 now.

And you're still a complete idiot for going that fast on public roads.

 

I have to disagree about usdm ecu's having a 158mph speed limiter. More like 115 to 120 that i have seen.

 

well thanks for the advice. the name calling was a little childish but i guess some people just cant help themselves.

 

Like I said, if you don't have enough power to overcome drag, you aren't going faster than that. I've known plenty of people that have gone well over 120 MPH with USDM ECUs.
USDM ECUs with JDM programs in them will speed limit at 180 kPH (111 MPH).

I'm not changing my position about going that fast on public roads. Seriously, either don't do it, or don't talk about it on a public forum. Just have some common sense.

 

YOU SAID IT WAS A PUBLIC RODE DUDE NOT ME..LOL

 

Well, you didn't correct me... If it wasn't on public roads, I withdraw my previous statements. And what's a 'rode'?