Quick question that I've asked many a time on B15sentra that never seems to get answered. I've noticed on the '99 and earlier G20's and SE's the redline is 7100rpm, on our new ones it's 6750. Why is this? is this how Nissan tuned the engine to get more power, or is my engine still capable of doing 7100 like the previous models, just with dangerous side-effects/consequences? okay so maybe it wasn't so quick

your b15 head is a roller rocker which doesn't allow you to rev as high

O

ps with a 94 g20 ecu my '99 will go to 7500rpm

'91-'96 Manual G20's have 7500 redline
:D

'99> went to the 7100 redline until the roller rocker was released.

Originally posted by OnyxEros
your b15 head is a roller rocker which doesn't allow you to rev as high


not necassarily.. the roller head will allow revs.. the valve srprings will not..

there are two cars that have roller head sr20s.. the 00-02 g20 and primera and they rev to 7000 rpms.. however.. the SE model sentras also have extremely shorter gears than the G20. which i feel may be the reason they shortened our rev limiter (basicly to make it so any bone head could drive it stock , and also making it extremely annoying to mod..)


i did a shift point calculation and estimate that with our short final drive and short gears. with at least 7000 rpms we would be a force to recon with. (which also makes us less ecomical but in many ways" faster " or "on par" with the older SR cars..)(no im not trying to start a big thing.. id love to see 90 in third.. but i like short gears better for acceleration purposes.)

hope this clears up any misconceptions..

edit corrected stock g20 redline for RR SR20..

Thank You guys! I think I'll stick to this site a lot more than b15. SR20DEe you say it would make our car faster, but then you say our gears provide better acceleration. could you please differentaite if you mean faster in terms of top speed or acceleration. I would assume you mean top speed, but then again i try not to make assumptions.
Follow up question: would it be safe, and/or would it increase performance to get an older ecu? how much would it cost, and what are the possible consequences?
Lesser importance question: I assume the roller rocker/valve springs are what gives the b15 SR20's the extra horse and torque then? could any one explain how?

Originally posted by jeff5speed
[B]Thank You guys! I think I'll stick to this site a lot more than b15.
both have good info of you can get past the flaming in b15..

SR20DEe you say it would make our car faster, but then you say our gears provide better acceleration. could you please differentaite if you mean faster in terms of top speed or acceleration.
if im not mistaken the shorter the gearing the faster the car gets through the rpm range.. adding rpms would extend the cars power by simply allowing it to have a FASTER engine speed thus granting MORE mph with our current gearing.. more than likely per gear at 7000 rpms it would be only a slight difference(like around 4mph i would think. that would put us at or around 60 mph shifting to third (like the classics of old but with a tad more umph..)

Follow up question: would it be safe, and/or would it increase performance to get an older ecu? how much would it cost, and what are the possible consequences?
do a search on b15 sentra.. theyve been talking about this before i even had my sentra..

Lesser importance question: I assume the roller rocker/valve springs are what gives the b15 SR20's the extra horse and torque then? could any one explain how?

extra horse may be from a bigger intake plenum which is actually longer than the LOW port SRs of old. i think the idea behind the rr system is valve train effeciancy.. i dont know.. but i dynoed 128 stock on saturday... whats that tell ya???

edit:::valve, drive whatever ;)

edit::: note to self on high port engines the tb is low.. the low the tb is high..