cam setup (stock cam selection and boost)

[neverlift]

I recently became owner of an s14 long block, and am curious if doing any of the options I have are worth it.

I have stock 91 cams already in the motor 240/248, I read through djpantspecr's cam reflection thread(a hundred times), and the man said 240/232 is the best overall in his opinion, and is good for people going boost. I am trying to find a snail to slap on(can get someone a smokin deal on a to4 60ar its turbine made me get chub and I had to pass it, wont work with my ebay mani) but would like to do the swap now if the benefits are there...

LMK what you guys have tried and or liked/hated with your turbo setup,and if you ran it without boost all the local guys run aftermarket cam, as you know I dont get down like that

[simmode1]

I have stock 91 cams already in the motor 240/248, I read through djpantspecr's cam reflection thread(a hundred times), and the man said 240/232 is the best overall in his opinion, and is good for people going boost.

Just to clarify, he said that 240/232 was good for automatic 240's. His overall pic was 248/232. Although in a recent thread, he was asked if he still was a fan of the 248/232 swap and he said no. He now prefers the stock 240/248.

I'm not turbo, so I have nothing further to add but I've had the same exact question for quite a while now.

[neverlift]

thanks man I'll have to email him to see what he thinks, from a drivabilty POV I can see where stock is better, especially if the changes go untuned for...

IDK anyone else who has tried some with a boosted motor?Honestly I already have a turbo to go back on, it needs an oil inlet flange cause a z31 snail center housing is not threaded like every other t3 in the world

[WDRacing]

There should be very little actual driveability chang unless you go past 256* duration. I have always said bigger is better...obviously within limits...and I feel the same way with cams. Since you're not adding a ton of duration or lift I'd use the combo that provided the most flow...248/248 or 240/248. But never 232...

WD

[DevilMB3017]

While we're talking tech stuff for a minute, I have a question.

What is the reason for different sized cams? I know my '91 came with similar duration on I/E sides and my Brian Crower cams have the same duration I/E.

Do you get better turbo spool with more of one? What's the reasoning?

[simmode1]

I'd use the combo that provided the most flow...248/248 or 240/248. But never 232...WD

Everyone I've talked to that has experienced stock vs 248/232 vs 248/248 say that the topend 248/248 gives you isn't worth the low end and mid range that you lose going from 248/232. This is what I understand from N/A ka's

But with a boosted application, the turbo can recoupe the low and mid range and the top end from 248/248 will be even more beneficial.

But I guess we'll never really know until some publishes dyno results of each oem cam swap and aftermarket ones both in N/A and boosted versions.

[spank044]

248/232 (int) +2.5 FTW!

I had 248/248 with different degrees on both and then switch back to 248/232 and was immediately impressed allover again. Also I had more noticable power in the bottom end and I didn't stall under decel. I'm running 27 psi on a Hybrid K27 T3/TO4E with 650CC RC, custom 3.2 liter intake manifold, no emissions or IAVC, etc. I should do a build thread, but maybe this winter. Butt dyno and passengers are fully impressed and so are the cars I have dominated so far. On the local drag I run low 11's with the 248/232 and ran 12's with 248/248 just because of the bottom end. No dyno's to show HP differences, but they are there in the bottom end for sure. IMO rock stock S13 cams or the 248/232 (int) +2.5.

[WDRacing]

Everyone I've talked to that has experienced stock vs 248/232 vs 248/248 say that the topend 248/248 gives you isn't worth the low end and mid range that you lose going from 248/232. This is what I understand from N/A ka's

But with a boosted application, the turbo can recoupe the low and mid range and the top end from 248/248 will be even more beneficial.

But I guess we'll never really know until some publishes dyno results of each oem cam swap and aftermarket ones both in N/A and boosted versions.

Tuning for NA and tuning for boost is entirely different. Things like back pressure and boost threshold come into play with the KAT.

248/232 (int) +2.5 FTW!

I had 248/248 with different degrees on both and then switch back to 248/232 and was immediately impressed allover again. Also I had more noticable power in the bottom end and I didn't stall under decel. I'm running 27 psi on a Hybrid K27 T3/TO4E with 650CC RC, custom 3.2 liter intake manifold, no emissions or IAVC, etc. I should do a build thread, but maybe this winter. Butt dyno and passengers are fully impressed and so are the cars I have dominated so far. On the local drag I run low 11's with the 248/232 and ran 12's with 248/248 just because of the bottom end. No dyno's to show HP differences, but they are there in the bottom end for sure. IMO rock stock S13 cams or the 248/232 (int) +2.5.

Low end torque with a 4 banger is easy to lose. It's also the most note-able when lost or gained, since just a little seems like a metric ton. But I'll bet dollars to donuts that you'll make a ton more power running 27psi if you remove that tiny exhaust cam.

Butt dyno's are THE MOST uncalibrated sensors man...lol. I don't doubt you're making power, 27psi, that's roughly 270-whp in boost alone. Imagine how much more power you'd have if you actually let the motor breath.

Choking a motor is bad for power...are you making a bit more low end torque...maybe. But I bet if you compared a side by side dyno you'd be pissed at the power you're losing. If you're worried about torque loss, get a set of adjustable cam sprockets. Believe me, it helps

I don't know what intake you're using either, but that makes a HUGE difference on low end torque as well.

WD

[simmode1]

Thanks, spank044. I think thats what the op and I were wanting to hear. The impressions of a KA-T driver that has had both oem setups on their motor. Since we don't have any dyno sheets to look at, butt dynos are all we have to go on...

Plz do a build thread with dynos!

[WDRacing]

Thanks, spank044. I think thats what the op and I were wanting to hear.

If you just want someone to tell you what you want to hear then I can tell you anything you like bro...doesn't make it a reality.

Spanky is running 27 psi...so yeah, he makes power...has NOTHING to do with his cam selection. Running that much boost and using a 232 cam and claiming it's the best option is like winning the special Olympics...yeah, you won...but you're still retarded.

[480sx]

What is the Ka-T community going to do without you Brian?

[GTR PrYdE]

No comments on the BC 264 setup?

I've seen a few reviews, some good some eh...

[WDRacing]

I haven't used BC cams in a 240...I have used 256 and 264 cams in my Skyline. The turbo I used was far to big for the RB20, so I ended up going with 264 only because the car was basically drag only. No boost before 5k sucks.

256* is an awsome daily driver cam imo. Great for medium to high boost.

Unless you're running more then 14 psi, stock cams are the way to go.

WD

[DevilMB3017]

I have Stage II cams from Crower. (264/264)

I like them. I first had my engine rebuilt with lower compression forged internals and the cams. Without any tunes or anything, the new motor was stronger then the old, no question.

With the turbo and ECU tune and everything I think my engine flows better. I have no way of proving it besides the fact that it FLOWS more air in and out of the motor.

Why you wouldn't want that is beyond me.

What is the advantage of running different cam spces on each side? Can anyone answer that?

[simmode1]

If you just want someone to tell you what you want to hear then I can tell you anything you like bro...doesn't make it a reality.

Spanky is running 27 psi...so yeah, he makes power...has NOTHING to do with his cam selection. Running that much boost and using a 232 cam and claiming it's the best option is like winning the special Olympics...yeah, you won...but you're still retarded.

You're always so touchy! I don't think anyone suggested that running oem cam was the best option for anyone. The op just asked for a comparison between the two oem setups.

Of course larger aftermarket cams would make more power, but thats not the question asked. I'm not trying to get into a pissing contest with anyone here, least of all you, WD. Just like the op, I'm seeking info.

I don't really have personal experience on the topic yet and value the input of the forum. From all that I'd read about cam selection, biggest isn't always best. It depends on where you would your powerband. Pulling info from a recent Cam shaft article in Modified, I understood that the different grinds of camshafts directly relate to different areas of your powerband.

For example 232 relates to your low end, 240 relates to the midrange, and 248 relates to your upper range. Combining 2 shafts of similar grinds (232/232, 240/240 & 248/248) will focus your torque curve in that region of your powerband. Similarly for 256, 264 & 272.

As I understand further, the use of using cams with different specs (lift/duration) will further alter your powerband. Like 232/240 would focus your power in the low to midrange, or 248/232 will focus on the top to low, overlapping in the middle. I have often wondered what running 272/256 would be like. Is that how some the the most famous KA-T's make their redonkulous torque numbers?

Please don't accept any of this as me stating facts. This is simply what I understand about cams. If it's wrong, I welcome correction and input.
Modified by simmode1 at 12:36 PM 9/30/2008

[DevilMB3017]

I gave up and started researching.

http://www.compcams.com/Information/Tutorials/

Read that.

Specifically the paragraph about overlapping the intake and exhaust phases, the fourth paragraph from the bottom...

Quote »"The next point on the graph is the intake opening. This begins the overlap phase, which is very critical to vacuum, throttle response, emissions and especially, gas mileage. The amount of overlap, or the area between the intake opening and the exhaust closing, and where it occurs, is one of the most critical points in the engine cycle. If the intake valve opens too early, it will push the new charge into the intake manifold. If it occurs too late, it will lean out the cylinder and greatly hinder the performance of the engine. If the exhaust valve closes too early it will trap some of the spent gases in the combustion chamber, and if it closes too late it will over-scavenge the chamber; taking out too much of the charge, again creating an artificially lean condition. If the overlap phase occurs too early, it will create an overly rich condition in the exhaust port, severely hurting the gas mileage. So, as you can see, everything about overlap is critical to the performance of the engine." [/quote]There are so many variables with different turbos, different valves, different head gaskets, etc. that could affect what exactly happens at overlap...and of course if you ROM tune yourself or use MegaSquirt or anything really, you could affect this by tuning for different ignition timing, fuel delivery, etc.

With a bigger turbo charger, it seems that you'd want a slightly longer exhaust valve duration, and a slightly earlier opening on the intake valve, just to pull more exhaust through you motor to help spool time. This could cause you to run a little leaner, however - which would have to be corrected by a tune I guess.

[simmode1]

Nice link! Thanks!

[NateDogg]

The best OEM option is stock, in my opinion. 240/248. You don't have to worry about mashing pistons with the '4 teeth rule'. If you want to 'tune' your powerband, get some adjustable gears.

Hopefully nissanfanatic will post his stock vs 264 dyno chart in here for proof.

[spank044]

I'm not retarded, I'm SPECIAL!!!!. I know I am losing power in the top end, but that consistent second I lose in the 1/4 mile is good enough compensation for me. I am not going for all out power, just a good e/t. I have consistent reaction time and 60.

With the 248/248 I cannot for the life of me break loose going into third, but with the 248/232 then I can break loose if I try and chirp into 4th.

WD I do have the DIY adjustable cams on both int and exh and have tried many degree combos. I even got so far out I needed all new exhaust valves. I can't afford to rent a dyno for the day and publish 18 different graphs just to show my numbers.

From all that I'd read about cam selection, biggest isn't always best. It depends on where you would your powerband. Modified by simmode1 at 12:36 PM 9/30/2008

Word to that. It is all about where you want your power. Next year when I am launching on the hose I will probably put 248 +2.5/ 248 -2.5 back in or buy 264's to utilize the top end crazy power, but right now I need my power onset to be in the low end.

[neverlift]

damn I can stir a pot, with so little efforts

honestly I have no clue in this area, other than the info posted on nico by djpants and others, I like my low end power(I dirft goddamnit and thats my thing) , but at the same time dont care for the whole loss of power after 5.5k... I would love a little more up top.

spank your info is spot on what I wanted to know(timeslips), cept you dont run a stop manifold, so I think that has some role in the faster et and 240/232 .

wd I understand what you mean more cam lift/duration is a part of making more power, but so many have stated they loved the pull of the 248/232. SO I asked for the kat crew to chime in

at this point I am leaving it, until I get boosted back up, got shafted on a turbo, then replaced and I ****ed the gd ceramic wheel on a rb turbo today 100 bux in the trash

[spank044]

That's my intake .

[480sx]

I'm not retarded!!!!........

I do have the DIY adjustable cams on both int and exh and have tried many degree combos. I even got so far out I needed all new exhaust valves.

Quote of the month right there.

Neverlift just run the damned turbo with low boost dude. Under 10 and your fine. For 10 psi of boost, 100 bucks isnt a bad price heh.

[neverlift]

oh no I refuse to run it like that, It looks like its ready to fall apart.

I am trying to get a rebuild kit for the seals on a z31 t3 , had I known as much about them when I got it as I do today(research was late lol) I would have passed. I can accept it and move on. Plus the turbine wheel is TINY and I cannot in any way see it flowing as much as my old volvo snail or the z31 snail with a volvo .48 turbine housing. btw are z31 turbo's super 60? if so is that trim

spank see that is nothing short from sechs however I really see it playing a role...

[DevilMB3017]

wd I understand what you mean more cam lift/duration is a part of making more power, but so many have stated they loved the pull of the 248/232.

Read that article I posted a link to.

With the overlap of the intake, they're sucking in more air earlier and not forcing enough air out. Depending on the degree they use it can actually have some of the spent charge stay inside the combustion chamber.

It IS possible they make more power this way because they aren't burning all the charge on spark I think. This would make the motor run a little bit leaner and possibly produce more power. I'm not 100% of that statement though. If that is true, it means that their ignition system isn't up to par, which is probably true when you think about the stock ignition setup and what abuse a KA-T gives it.

I'm not trying to argue or anything, I just want 100% solid proof that flowing less air into a motor can be a good thing. It just doesn't make sense to me.

[WDRacing]

Read that article I posted a link to.

With the overlap of the intake, they're sucking in more air earlier and not forcing enough air out. Depending on the degree they use it can actually have some of the spent charge stay inside the combustion chamber.

It IS possible they make more power this way because they aren't burning all the charge on spark I think. This would make the motor run a little bit leaner and possibly produce more power. I'm not 100% of that statement though. If that is true, it means that their ignition system isn't up to par, which is probably true when you think about the stock ignition setup and what abuse a KA-T gives it.

I'm not trying to argue or anything, I just want 100% solid proof that flowing less air into a motor can be a good thing. It just doesn't make sense to me.

Pretty much exactly what I'm saying.

I'm not trying to start a pissing contest either guys, I'm just stating opinions like the rest of you. I just happen to think running a big intake cam and tiny exhaust cam is a bad option.

All of this depends on tune and turbo though...so Spanky's combo isn't going to work the same on anyone elses KA. Because he has a custom 1 off intake, adjustable gears and a not so common turbo.

WD's CAM selection is 248/248 FTMFW

EDIT

I'm never going to stifle creative thinking or personal idea's. I may call you a retard or give you a title like brain fart, but that's just me screwing with you guys.

WD

[DevilMB3017]

The more I've been reading and thinking about this, the more I don't understand.

If the stock cams have the same lift, but vary in duration, the only thing you are doing is changing the time period of the valve staying open or closed.

Couldn't this lead to things like pre-dentanation considering the timing of the whole combustion cycle will be off? If you have more charge going into the combustion chamber, and less coming out, aren't you going to keep the pressure in the combustion chamber higher? Also the EGTs will be higher because of this - I think EGT tuning is something that is being overlooked in our KA-T community. Having a good AFR can still lead to horrible performance...

On the flip side of that, the EGT being higher could lead to BETTER performance if your running too cold. There are so many variables in choosing cams that I think you really need to talk to a dyno-tuner about what your specific setup and goals are. I can't wait until my car is running good long enough to switch to a standalone and get that sucker tuned right...

[480sx]

EGT is overlooked by most people and is extremely helpful when tuning.

Idk i need to learn more about duration/lift, and mostly overlap before i can really add much if anything to this thread.

[DevilMB3017]

Idk i need to learn more about duration/lift, and mostly overlap before i can really add much if anything to this thread.

Same here. I actually first started looking into it because of this thread. It looks like something very interesting. I'm looking at some 'Stage 2' cams from different companies and it looks like they use the same or very similar cams on I/E on DOHC motors. I wonder if this is for performance or to save money/make the parts cheaper. The higher 'stages' tend to be a little different I/E...

Lots of unanswered questions, lol.

[simmode1]

Lots of unanswered questions, lol.

Yeah. We need something like that camshaft mega thread they got over in the SR forum. Or somebody write to Modified Magazine and ask them to do our homework for us...

[neverlift]

well I could in theory test this, using my w/b and gtech, get the weight checked at the wrecker....even get into the cam gears(ANY SUGGESTIONS for this would be good!)...

however its not going to be as usefull cause of the whole I need to get a rebuild kit for this stupid turbo, so I will be n/a for the testing... waste nevermind, it can wait till I get the snail back in action

in the time being you guys feel free to test and get back to this thread