What valvesprings do you have and how high do you rev?

[zippitta]

I was just trying to get an idea of how high you are able to rev with different valvesprings. Im looking at Ferrea's valvesprings. Thank You.

[sunnys14]

ferra valve springs should be able to hold up pretty well, but the KA just isnt a rev happy motor...

[C-Kwik]

The bottom end will likely kill itself beyond about 7500 RPM. The long stroke makes the harmonics of the KA quite poor for high revving. Unless you are running some high lift cams, I wouldn't bother with stiffer valve springs. They do add additional drag to the drivetrain. The DOHC KA's valvetrain is quite good.

[zippitta]

Besides JWT, who else makes cams for the KA? I think it was crower that had a set of cams but they ran out of blanks or something like that.

[sunnys14]

s13 cams can do fine if u use 248 248 duration on both intake and exhaust

[driftin2trance]

is 248/248 best for turbo setup?

[95_240sx]

The bottom end will likely kill itself beyond about 7500 RPM. The long stroke makes the harmonics of the KA quite poor for high revving. Unless you are running some high lift cams, I wouldn't bother with stiffer valve springs. They do add additional drag to the drivetrain. The DOHC KA's valvetrain is quite good.

I do not believe that is true. I am as big of a proponent as anyone on here to spin the motor up a bit. The rod ratio is a 1.71, and piston speeds dont get out of hand until around 8500rpmish. I have personally spun my motor to 8-8.5k at 30+psi of boost on probably 100+ occasions and never had a problem. Granted it is a built motor, and by a damn good engine builder, I still do it and can attest that the KA DOES go past 7500rpm.

Rick

[zippitta]

you can put a 248 intake cam on the exhaust side?

[ka24de-t_Dreamkid]

I thought the Duration of the Exhaust cams are 248. and you use both exhaust cams not intake cams. s13 91-93
Modified by ka24de-t_Dreamkid at 9:30 PM 11/29/2005

[nissanfanatic]

You use two S13 Exhaust cams to gain the 248 248 setup.

PDM-racing also makes KA cams.

[zippitta]

I thought the Duration of the Exhaust cams are 248. and you use both exhaust cams not intake cams. s13 91-93

my bad, I got it confused.

[zippitta]

So, does anybody know when Crowers' Cams are going to be available and who I could get them from?

[C-Kwik]

I do not believe that is true. I am as big of a proponent as anyone on here to spin the motor up a bit. The rod ratio is a 1.71, and piston speeds dont get out of hand until around 8500rpmish. I have personally spun my motor to 8-8.5k at 30+psi of boost on probably 100+ occasions and never had a problem. Granted it is a built motor, and by a damn good engine builder, I still do it and can attest that the KA DOES go past 7500rpm.

Rick

It should be clear that a stock KA is what I was referring to. There are NASPORT KA's that rev beyond 8000 RPM. But that's with a lot of work. You can try to eliminate the harmonics problems, but you still have to contend with piston speeds. The KA does have a good rod ratio, but piston acceleration is still very high due to the long stroke. A VTEC Honda motor has short strokes so at 8000 RPM, it's pistons do not have to travel the same distance as the KA's pistons in the same amount of time. Piston speed in that of itself is not the problem here either. Piston acceleration does. Given that a longer stroke requires that a piston travel a longer distance in the same amount of time, it would have to accelerate faster. A good rod ratio may slow down the acceleration slightly in the center of the stroke vs a shorter one, the peak piston acceleration occurs at TDC and BDC. And you would likely need a built bottom end just to handle the tensile loads on the pistons and rods. This is especially a concern as tensile loads can cause fatigue to metals over time, where compressive loads do not.

Given all this, a built motor will be vastly different than one that is not. But JWT does say a stock KA has inherent vibrational issues at above 7500 RPM. I think they have built many more race KA's than any of us.

[grimple1]

So, does anybody know when Crowers' Cams are going to be available and who I could get them from?

Ivan has been fighting this battle for a long time now. turbo240.com

Good luck!

[Chezedik]

I think Zip is running SOHC. The pic in the sig is a pignose. And kind of a rough looking one to begin with.

[nismofly]

however he mentions crower cams, which makes me think he probably swapped in a de

[Chezedik]

Good point, but does Crower not make one for SOHC.

[Structure240sx]

Crower doesnt even make a set for the dohc anymore

[Chezedik]

Not terribly surprising, are they even still using it in Frontier?

[zippitta]

Yes my car is ruff looking...but there is a reason for that. I am not worried about the cosmetics right now. The motor build is of main concern right now. I have the DE. After the motor is completely finished and tuned in, then I am going to sand it down and paint it black. Keep it as simple and as light as possible.

Crower will still hard face stock cams correct?

[95_240sx]

It should be clear that a stock KA is what I was referring to. There are NASPORT KA's that rev beyond 8000 RPM. But that's with a lot of work. You can try to eliminate the harmonics problems, but you still have to contend with piston speeds. The KA does have a good rod ratio, but piston acceleration is still very high due to the long stroke. A VTEC Honda motor has short strokes so at 8000 RPM, it's pistons do not have to travel the same distance as the KA's pistons in the same amount of time. Piston speed in that of itself is not the problem here either. Piston acceleration does. Given that a longer stroke requires that a piston travel a longer distance in the same amount of time, it would have to accelerate faster. A good rod ratio may slow down the acceleration slightly in the center of the stroke vs a shorter one, the peak piston acceleration occurs at TDC and BDC. And you would likely need a built bottom end just to handle the tensile loads on the pistons and rods. This is especially a concern as tensile loads can cause fatigue to metals over time, where compressive loads do not.

Given all this, a built motor will be vastly different than one that is not. But JWT does say a stock KA has inherent vibrational issues at above 7500 RPM. I think they have built many more race KA's than any of us.

I would imagine that the person asking the question is planning on doing a built motor. Also, like I stated before, *I* havent ever had any problems with my car, wether it be the bottom end, or valvetrain/head. Without sounding conceited, I think that I have slightly better resources at my dispsal and more cumulative experience from all of us than many people who are just starting out in the turbo KA world. Yeah, I think that at 8700rpm or something the FPM on the pistons are like 5800ish.

Rick

[Jookmasta]

i wasnt aware that crower didnt make cams anymore for us.........since when? coulda sworn they had that v3 come out a while back............any reason as to y they stopped making em?

[AeonTorpor]

I would imagine that the person asking the question is planning on doing a built motor. Also, like I stated before, *I* havent ever had any problems with my car, wether it be the bottom end, or valvetrain/head. Without sounding conceited, I think that I have slightly better resources at my dispsal and more cumulative experience from all of us than many people who are just starting out in the turbo KA world. Yeah, I think that at 8700rpm or something the FPM on the pistons are like 5800ish.

Rick

The FPM of the pistons you gave "5800ish", is the average piston speed. maximum piston speed occurs at mid stroke w/ the piston rod at 90° from bdc. Which is also bad because of the steep rod angle and the increased cylinder friction. The maximum piston speed would be closer to 12,000 FPM (i'm not going to calculate the real RPM!), which is closer to 140 MPH. So... that's fast, and that says a lot if you don't know what your rods and your pistons are rated for. Or even how to calculate that. And for not calculating that, you have no clue what kind of RELIABILITY you'll have while running your motor up to the 8.5k RPM you say you've ran it too. And even at that point, the piston ring lands, springs that are really meant for nothing more than 7500 reliably, the rods themselves, headgasket (esp. w/ boost) or many things could fail while running that high. But it's good that you haven't had problems thus far, knock on wood.

BUT... my take on the original topic. Stock if you don't have serious balancing done to the bottom end (all of it) and don't have strong *** rods and pistons, then overrevving is not great for the engine, regardless of the valve springs. It's a whole culmination of things that leads to it's lowered redline. So yeah, stock springs til 7500, but new, higher rated would be better. IMHO making a project to "over rev" the ka just isn't a totally fulfilling goal. To do it for long term reliability and overhead, now that's a good goal.

[Mikoriad]

I'm damn afraid of taking a good condition stock DE to only 6k! It just feels so bad compaired to other cars. ..... glad I could input some good info here btw

[klattr1]

do you think Nissan would have set the rev limiter on the S13s/S14s where they did if they were afraid it would mess something up?

[Nismo_Freak]

Spins to 10700 RPM.

Oh and thats on 15 PSI with stock cams.

[klattr1]

and that would be a SR20VET....

[Jeff240sx]

do you think Nissan would have set the rev limiter on the S13s/S14s where they did if they were afraid it would mess something up?

Messing something up is only a very small part of why the rev limit is set at a given point on a KA. Proof? That s13 is 6800rpm, and s14 is 6500rpm. By assuming that the rev limit is set to prevent damage, that implies that the s13 is either more resiliant to rev stress (which it can't be, as it's the same motor dimensionally), or that s13 owners simply get less leeway on overrevs (which isn't the case either).The rev was set, on each chassis, to the point where the engine runs out of breath and usable power. Further revving wouldn't be beneficial from any driving standpoint. Proof? The hotter cams give the s13 more revs. My motor is built.. and I spin it to 7500rpm on every trip down the track, with the help of cams and a turbo to increase VE past 7k.-Jeff

[klattr1]

you can have a motor that breathes good to a certain RPM, but that doesnt mean the valvetrain would support it (valve floating or whatever). so setting a rev-limiter has to be made equally on both parts.

i was just pointing out to Mikoriad that Nissan wouldnt have done it if they didnt feel that the valvetrain would support it.

thats all.
Modified by klattr1 at 11:18 AM 12/17/2005

[Nismo_Freak]

and that would be a SR20VET....

Mmmhmmm...