I know somebody was looking into this, but nothing TMK ever came of it. Two core questions:
Does anyone yet know if the old-style valve springs are compatible with the new-style roller cylinder head? Does anyone know if there is any variation between valvesprings on rollerized, low-port engines?
First, I want to know if JWT or JUN springs will work in my (or a P11, or an S15) cylinder head. Second, I want to know if the S15 and non-US P11s, with their 7200-RPM redlines, are any different from my springs, which Nissan only blessed with a 6700 RPM redline.

Hear, hear. I'd love to hear my engine sing to the tune of 7200 RPM, especially with my S3's.

I was thinking more along the lines of 7800, with JUN or JWT coils. ;) I'd be pretty happy for quite a while with 7200, though... With a Primera ECU image and a G20 final drive, I gauran-frickin'-tee ya' that I could hit 60 in second gear and trip a quarter in third.

Edit: Looks like I'm smokin' crack about the G20 gearset; according to my [limited] sources, it's the same one I have (4.072:1). Would be pretty interesting if the QG18DE's transmission used the same R&P, though, as it's only 3.827:1. Now that could give me some legs...

why would you want a taller final drive?

now im not sure if it was the light weight springs or the light weight valves them selves that make the RR valvetrain weak beyond 7200.. maybe a combo of both.. no clue.. any input? ;)

as far as the final drive.. i would keep the shorter gearing hack on the revs and zip zip zip to 100 everywhere i go ;) ok maybe not ;)

imho our slightly larger cars need the Shorter gearing to keep in on edge with the smaller sr20 vehicles.. turboing is another story. im thinking in a N/A world.

dren.. suggested idea is go buy 8 parts.. 1 e/i valve from each valve train and i/e springs.. i was going to do this but.. im slow.

check out the differences from there.. or do what i did go on b15sentra.net and ask for help from travis about the valvetrain differences (since hes gutted several sr20s) which didnt work :rolleyes:

Originally posted by CowboyDren
Looks like I'm smokin' crack about the G20 gearset; according to my [limited] sources, it's the same one I have (4.072:1).

i thought the SE final was 4.43:1

maybe im smoking crack??

Originally posted by slipper
why would you want a taller final drive?
Because I waste too much time shifting gears. Yes, a shorter final drive does help our heavier cars out of the hole, but I really don't care about that at all. I want to be able to merge with traffic on the freeway without bouncing off the rev limiter. Dig?

The only time that a shorter final makes a measurable difference is at the drag strip anyway, which would be time better spent (again) not shifting, so taller we go.

According to the specs I've found, the SE has 4.43 (or something like that) final, while the SE/PP has the 4.072 gears. Not sure exactly why, but that's what it says.

The lightweight valves have little to do with rev-resistance. Actually, the higher you rev, the lighter they need to be. It's all about the valvesprings in this particular case.

Trav (username "unlucky" on this board) doesn't know if the springs fit or not; I've asked.

Don't make book on this, but I seem to recall from discussions on the SE-R mailling list that the roller-rocker valve springs are too soft to deal with higher rpm. In the never-ending quest for fuel economy, engine drag was reduced by lowering revs, which allowed softer valve springs, which produced less friction on the cam followers.

Right. I give precisely two shits about fuel economy though; I want more RPMs. I've resolved myself to the idea that I may need aftermarket springs (or maybe just old OEM springs) to reach my RPM goal. It has been established that 7200 RPM is the safe limit of my current springs by JWT, which either means that they're being too conservative (typical of JWT), or my springs are actually softer than every other rollerized head in the World. Hence my questions above.

the roller springs are less strength because the are shorter and run closer to binding the coils if they are stronger. normal de springs shouldnt be used. jwt is working on some springs for the rollers i think. just because they are not as springy doesnt mean they cant handle high rpms. valvetrain is a lot more complicated than suspension springs. if you dont need springs dont buy them because you dont need them unless you have cams that require it.

Originally posted by bigtom
if you dont need springs dont buy them because you dont need them unless you have cams that require it.

which you would require them if your running 11:1 compression 7800 rpm redline and possibly s3 Or higher cams.. im pretty sure that no one would really want to ONLY invest in springs for the revs.. i would do it as part of a internals upgrade..

Originally posted by CowboyDren
Because I waste too much time shifting gears. Yes, a shorter final drive does help our heavier cars out of the hole, but I really don't care about that at all. I want to be able to merge with traffic on the freeway without bouncing off the rev limiter. Dig?

The only time that a shorter final makes a measurable difference is at the drag strip anyway, which would be time better spent (again) not shifting, so taller we go.

According to the specs I've found, the SE has 4.43 (or something like that) final, while the SE/PP has the 4.072 gears. Not sure exactly why, but that's what it says.

The lightweight valves have little to do with rev-resistance. Actually, the higher you rev, the lighter they need to be. It's all about the valvesprings in this particular case.

Trav (username "unlucky" on this board) doesn't know if the springs fit or not; I've asked.


sorry to quote the entire post......

ya know.. let me bounce off the rev limiter.. just let me get up to speed quickly. sure its short and you may bounce. but you'll also have another 1000 rpms to work with..

as far as raising the revlimit itself on this car.. I would do it like i said above.. the total package... completely shifting the heft of the powerband to above 5500 rpms.. that way when i shift at those i rpms i have some torque to fall back on...(looking at what i just said.. longer gears would be cool huh)

picks up crack pipe... :rolleyes:

could there be a chance that the valve springs be custom made???

You guys are missing the point. All of this speculation over whether I need stiffer springs or not is moot; I know I need them! I intend to raise the rev limit on my car, if not to 7800 or 7500, at least to 7200. Since 7200 is the limit of the stock valvesprings, I need different ones to be able to safely exceed that limit.

A final drive change may also be in order, but is a seperate issue, and valvesprings with a little ECU tweaking are just as easy and probably cheaper to try first. I can get an OBD-II G20 ECU (7500 RPM rev limiter) with sensors and harness for under $300, and I'm sure I could help somebody get rid of stock valvesprings for less than that. God only knows how much a new R&P set cost, then they have to be installed, so the price points are very close. If I could find the P/N on the South American P11 map BIN image (7200 RPM), and a friendly Nissan tech to flash my ECU, I'd be in for a lot less than either of the other three options (I didn't bother listing a JWT B14 ECU).

bigtom: I recognize and respect your points, but how do you know that the old-style springs (OEM or aftermarket) cannot be used, and to whom have you spoken at JWT that would indicate they are making new springs?

In my opinion it would be easier to swap the head to a older one. Swapping valvetrain with the head in the car is back breaking work. I would much rather pull the head off.

fwiw, I ran my stock valvetrain to 8k a few times prior to installing the JWT valvesprings without any damage being done.

Buying a new head and intake manifold will probably cost nearly as much as a JWT ECU, though. Additionally, I'm not sure if it will even bolt up to the new block casting, which isn't a 53J like every other US SR20DE is.

i personally would think that the RR valve train would be more ideal than the old styled valving.. however.. some nit *** engineer thought they should make the sr20de more economical :rolleyes:


jon im watching you.. if you are able to make this rev limiter thing work..your sharing the image of the ECU ;)