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Discussion Starter · #1 ·
I have two questions, especially for G20 owners with roller rocker engines. A service manual is probably handy, though you may be able to get some data from the emissions specifications under the hood.
  1. What is the redline on US-spec G20s? I've heard more than once that y'all have 7200 RPM before spark cut, but the (ahem) drawings in the (ahem) owner's manuals only shows 6700. Which is it?
  2. What is the base idle speed on cars with automatic transmissions? Does it vary from manuals?
I'm wondering aloud if I could use a G20 (A/T) ECU in my lowly Sentra SE (M/T), and what gains it could offer. The redline question is simple; I only go to 6700 and it annoys the crap out of me. Non-US SR20/RR engines have 7200, why can't I? ;)

The automatic idle question is a bit more complicated and harder to justify. I was browsing through the '00 B15 FSM, and found that the QG18DE engine has different idle speeds for M/T and A/T applications; M/T: 650±50, A/T: 800±50. Now this doesn't apply so directly to the SR20DE powered cars (All: 800±50), but there's a glimmer of hope, and you can't take away hope. ;)
 

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Discussion Starter · #2 ·
Oh, c'mon, now, nobody with a Roller engine knows their redline or base idle? Sheesh.
 

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I believe the roller rocker G20's have a 7,000 RPM redline on the manual and a 6,800 RPM redline on the auto.

The '91-'96 G20's Manuals hit it at 7,500 and Autos at 7,250.

Anyone with the roller SR20 P11 care to enlighten our friend here?
 

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What is meant by roller engine???



BTW I have a 2002 G20 and it cuts out at 7200 RPM.
 

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Discussion Starter · #5 ·
Gally14 said:
What is meant by roller engine???
SR20DEs built since '00 use a different type of valve train gear than previous ones do; they have rollerized parts (the tappet, I think, is what's actually rollerized, but I'm not sure).
BTW I have a 2002 G20 and it cuts out at 7200 RPM.
GIVE THE MAN A COOKIE! :D That's half of the answer. Can you look at the stickers under your hood for me and see if the idle speed is listed? Is your car manual or automatic?
 

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CowboyDren said:

SR20DEs built since '00 use a different type of valve train gear than previous ones do; they have rollerized parts (the tappet, I think, is what's actually rollerized, but I'm not sure).
GIVE THE MAN A COOKIE! :D That's half of the answer. Can you look at the stickers under your hood for me and see if the idle speed is listed? Is your car manual or automatic?

wheres the sticker, i might be able to find out. 02' 5-speed
 

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Discussion Starter · #7 · (Edited)
Dammit, I think I'm wrong about the sticker. I just looked under the hood of my own car, and the sticker that should say what the idle speed is says, "No adjustment necessary" instead. Stupid non-owner-servicible cars.:angry: If your sticker does list an actual idle speed, I'd like to know.

How many will confirm a 7200 RPM redline?
 

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About the roller engines. Are there advantages/disadvantages to them?


Getting back to RPM issue, If the older G20 manuals hit 7500, can you put that ECO into a manual 2002 G???
 

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Discussion Starter · #9 ·
  1. Yes, they're smoother, and thus cooler and more economical fuel-wise.
  2. No. The pre-'00, non-RR ECU is totally different from the '00+, RR ECU. They are entirely physically dissimilar. You wouldn't want to, though, because the valvesprings in RR heads are only good enough for 7200 RPM.
 

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I don't have an FSM but do noticed that spark cut off at around 7000-7200 rpm. More so the latter.....but you can't really rely on the guage. The tech data should confirm more.

As for idle, before advance timing, it idles at roughly 820 rpm but now is about 920 with 19 degrees advanced timing.
 

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Discussion Starter · #11 ·
That's wild. Your timing light has a tach? I need to get one of those. :)
 

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what? timing light has a tach? no no no.....after the advance timing, my idle rmp went up for some old reasons. I doubt the probe light Jason used has a tach - that would be cool nonetheless!
 

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im sorry to butt in wierdly..

at one point their was a dyno on this page.. but since this page went forum their is no longer that dyno.. is that still archived somewhere on this page... i beleive that it was a manual transmission 01 p11. i could be wrong.. but in either case it would help out a little. :monkey: :monkey: :monkey:
 

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also according to the infinity car website the redline is 7000 rpms.. thats a little better but not much.. the gearing ratios in the Sentra SE and the Manual G20 are an exact match edit::::(minus final drive.. ).. i guess its safe to assume that the G20 deffinately needs the revs more than we do ;) in either case thats a good 300 rpms difference.. thats our second gear 60 mph dren ;)

:bandit: :bandit: :bandit: :bandit: :bandit: :bandit:



now for that darn encoder key crap :mad: :depressed
 

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Discussion Starter · #15 ·
G-loads said:
no no no.....after the advance timing, my idle rmp went up for some old reasons.
Then something is wrong. You need to get that checked out, perhaps with a timing light that does have a tach.
SR20DEe said:
the gearing ratios in the Sentra SE and the Manual G20 are an exact match edit::::(minus final drive.. )..
Is that to say that the final ratio is higher or lower than an SE? Can you link me (us) to your sources? Perhaps somewhere there's a G owner looking for better economy. ;)
thats our second gear 60 mph dren ;)
You're a mind reader.
now for that darn encoder key crap
Nah; all you have to do is match the key to the ECU. No biggie.
 

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Discussion Starter · #17 · (Edited)
Excellent points, dude. I'm comparing three cars, here;Between these vehicles, there appear to be a lot of variance between what the Bureau reports and what's actually on the road, such as the advertised 6600 RPM redline on Sentras. That information seems to indicate that the transmission in a G20 is more similar to the transmission in a Sentra XE/GXE, which can't possibly be right. The ratio information would be interesting if it were correct, though; a Sentra SE and G20 automatics' final drive set would be the longest-legged of them all (wonder if it'd fit in a manual box). Conversely, the Sentra SE 5-speed has the shortest (highest numerically).

Back to the ECU issue, I think the easiest thing to do would be to find somebody with access to the G20 maps and a Nissan ECU "burner" to do the work. This way, you would keep your key even with the new ECU. It should be pretty straight stuff if you have the equipment. If you had access to that, you could probably have access to a CONSULT-II, too, and switch to the high-altitude fuel and spark maps. :evil:

I'm going to disqualify that source as being authoritative and accurate. Let's find another. ;)
 

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CowboyDren said:

Back to the ECU issue, I think the easiest thing to do would be to find somebody with access to the G20 maps and a Nissan ECU "burner" to do the work. This way, you would keep your key even with the new ECU. It should be pretty straight stuff if you have the equipment. If you had access to that, you could probably have access to a CONSULT-II, too, and switch to the high-altitude fuel and spark maps. :evil:


hmm.. now im not too sure of consult and the actually fuel mapping procedure. but.. coudl it be said if i could find someone with the consult II system could they not just configure it to the specs of the G-DUb?

and actually wouldnt they be able to just mapp the fuel and spark of a g-dub then go and set it on the SE??


:monkey: :monkey: :monkey: :monkey: :monkey: :monkey: :monkey:
 

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Discussion Starter · #20 ·
As I understand it, the CONSULT-II doesn't change maps, but it can switch them. I was told (!) that there are three maps in the ECU, the standard map (which all are set to), an aggressive map (for high-altitude), and a conservative map (for people needing a quick fix). I can only assume (!) that this is for not only spark but fuel curve.

The reason for having them is plain enough, it's just a matter of confirming that they exist or that they are a figment of my imagination. You'd want the Conservative fuel and spark map for a car that's having trouble, and you need to let it limp around for a while until you can get it fixed properly. This would fatten up the fuel trim and dial timing advance out, so as not to overheat the cylinders. The Aggressive map would come in handy at high altitudes where you 1) need every ounce of power you can safely get and 2) can get away with running lower-octane fuel.

The CONSULT-II (referred to by me as "C2" from here out ;)) is just a tool to help you get what you need out of what's already in the ECU, not make the ECU capable of things it wasn't set up for. If you want the G20 program, you'll need a bigger device. Know what'd be really phat? The S15 N/A program. ;)
 
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