B15 Sentra Forum banner

1 - 20 of 51 Posts

·
Registered
Joined
·
101 Posts
IB4TL... No, No one has cracked the ECU code. Let some one else go into detail on this
 

·
Registered
Joined
·
5,244 Posts
funktype21 said:
Has anyone been able to reprogram their ecu and up the rev limiter and speed govenor??
The status of the JWT ECU is unknown at this time. Technosquare I believe cracked the ECU, but their frist tester car blew it's motor.

You can't up the revlimiter to much on the QR25 because the vavletrain is weak and your motor won't make much power (if any at all) past the stock revlimiter.

There is no electronic speed limiter on any B15. The top speed is goverened by drag, and once you are producing enough HP to overcome that drag you will just run out of gears.

I hope that helps. Many of these topics have been covered in detail in the past, so fee free to use the search function to bring up further information.
 

·
Registered
Joined
·
59 Posts
You can't up the revlimiter to much on the QR25 because the vavletrain is weak and your motor won't make much power (if any at all) past the stock revlimiter.
QUOTE]


I am guessing that would mean on a completely stock motor? Dumb question, but I felt the need to ask.
 

·
coming soon
Joined
·
14,392 Posts
lakers said:
You can't up the revlimiter to much on the QR25 because the vavletrain is weak and your motor won't make much power (if any at all) past the stock revlimiter.
QUOTE]


I am guessing that would mean on a completely stock motor? Dumb question, but I felt the need to ask.
stock cams won't make any more power with a higher rev limiter.

as it is...the stock crank can't take much more than 7100-7200rpm without eating itself alive.
 

·
Fast **** box
Joined
·
2,005 Posts
chimmike said:
stock cams won't make any more power with a higher rev limiter.

as it is...the stock crank can't take much more than 7100-7200rpm without eating itself alive.
What he said. Seriously on the stock valvetrain and crank you won't see any gains. Hey Chimmike, how many times have you see nthis asked?
 

·
NG Autoworks
Joined
·
7,504 Posts
cburwell said:
You can't up the revlimiter to much on the QR25 because the vavletrain is weak and your motor won't make much power (if any at all) past the stock revlimiter.
The valvetrain is actually fine. It's a lot better than the SR valvetrain. The QR25 valvetrain is good to around 6500 or more rpm. Beyond that you would need stiffer valvesprings to prevent float. Otherwise I see no reason you couldn't go that high with the stock valvetrain.

The limiting factor with the QR25 revving so high is the rod to stroke ratio. A destroked QR, or a QR with a better rod to stroke ratio could rev further than an SR could ever dream of. A good combination would be a sleeved block, bore to around 90-91 mm, and destroke the engine. This would provide your high displacement, with ability to make power (with the right cams) way up in the rpm range, paired with viable low end torque.
 

·
NG Autoworks
Joined
·
7,504 Posts
chimmike said:
stock cams won't make any more power with a higher rev limiter.

as it is...the stock crank can't take much more than 7100-7200rpm without eating itself alive.
The stock crank is also fine. You should be able to easily take it to 7500 rpm, I have heard some people say the QR crank should not be revved above 7200 rpm b/c of harmonics, but I do not believe this to be true. The older KA24 has problems with harmonics, and I've read that even a bone stock KA24 damn near vibrates itself to death at high rpm. The QR motor, however, is a different beast, and is nothing like the KA24.

Like I said before, the rod to stroke ratio is why the QR cannot rev that high. Also, there is no point to rev that high without a new cam.

Furthermore, a stock cammed QR25 could benefit from a few hundred more rpm (200 or so) and still make power.

To remedy the rod to stroke ratio, you could either use a different crank, or a longer rod....but there is only so long you can go with the rod. Even then, you'd be limited to around 7300-7400 rpm since the piston travels so fast.
 

·
Southern Shift Racing
Joined
·
2,511 Posts
Ahhh, Stephen, don't you just love the amount of misinformation that gets thrown around? lol... :rolleyes:
 
1 - 20 of 51 Posts
Top