my comments on 248/240 s13 cam swap

Information on the naturally-aspirated KA24E and KA24DE engines.
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DjPantsSpecR
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KA24DE cam swaps

Postby DjPantsSpecR » Sun Jan 08, 2006 2:56 pm

I've re-named this thread ot something more searchable, as i feel there is a wealth of info here for cam swaps. all of the impressions here are based on a 92 s13 hatch, automatic, fully rebuilt to stock by me, except apexi panel filter

i've tried 248/248, 240/248, 248/232, 240/240, and now i've tried 248/240

its been a while since i've tried any other cam swap besides 240/240, and i've never had 248/232 on the automatic car, but i did install it on a friends automatic, and it did net similar results to my manuel car so i feel it's semi-fair to compare

248/248 is by far my least favorite cam swap. there is a noticable loss in low end, and the motor never rev's high enough to take too much advantage of the additional top end power. I'm not saying the top end isn't there, it just really only starts pulling until right before 6000 rpm, and pulls to 7000. then you hit the rev limiter and crave for a few more revs. maybe an automatic ecu and 7200 rpm mighyt be beneficial, but i love to rev it out and i shouldnt be allowed to have 200 more rpm. if i had a more top end oriented motor 248/248 would be a great thing to have, but until i can afford it, i wont ever use it again. the sound you get from this beast is nice though

240/248 is obviously stock, its been a while since ive actually had a car with 240/248. but from what i remember the low end is decent but it does fall on its face in the top end. the 248 exhaust cam is trying to make top end power, but the 240 intake cam is trying to provide more all-around power, not just low or top end. i dont like it because of how bad it falls on its face before even 6500

232/232 i never tried, but i got em so i could.... but come on 232/232?

240/240 has a really snappy low end, probably the best low end ive tried, and its the only times ive ever spun the tires into second gear in the automatic, granted its gotta be wet outside... anywho, 240/240 is what i'm directly compareing to 248/240 here. 240/240 has a nice pull even in the top end, and power is quite prominent in the 4000 rpm area. i'm still a big fan of 240/240 and i'd like to try it on my manuel car, but that car already has the hands down best stock cam swap possible....

248/232 this is hand-down where its at. If you have some s13 cams and some s14 cams you should have already done this. the power production is great everywhere. you only lose a little bit of top end over 248/248 and you gain more low end than you get with any other swap besides maybe 232/232. the KA craves this swap, it loves the low end and, chances are you only rev to 6500 anyway, so thats why this is the cam sawp for you. only don't do this if you wanna get beat by me. i'm only kidding, i'm too poor to be fast.

248/240 you read all that crap just to get to here so here it is. coming from 240/240 in a nearly stock automatic car, i'm very disapointed. the only major difference is a slight gain in top end, maybe 2hp, but the loss of low end is noticable. i'd rather have that torque back for this daily driver than the slight bump i got in top end. granted this car is actually proven quicker now than the 240/240 car, but its less satisfying. everyone wants to be put into the back of their seat right away, not eventually.....

sound in 248/248 sounds the best, but 248/232 sounds 100% different, and also quite beautiful. idle with 248/240 sucks, but its nice because its honestl looping so it give the illusion of a fast auto....

EDIT: okay this is the only swap i think i didnt touch yet, and you wont even hear about for many posts down. Some of the posts in this thread are kinda off topic, but MANY MANY are very useful, and there is a large discussion independent of this thread by tloof that you can search for...

240/232 this is what i just put in my automatic car. im a huge fan of the low end here, and its better than 240/240. the overlap is always off by about 2 degrees or so when you use an intake cam used as an exhaust cam or vice-versa. So for that reason, 240/232 works very nice. i can tell it doesnt have quite as much pull in the top end as 248/232 but its part-throttle driveability is great. you really only feel the low end torque when you are at part-throttle anyways, so you need ot make a decision....

240/232 is great for a dailydriver, where low end torque is favored over top end merging power. in the automatic, after shifts the car has noticably more power than it does with 248/232. I would say if you have an automatic get the 240/232 because you spend more time in the midrange becasue of your gearing.

248/232 is for the manuel car. ive gone to and from this cam swap in both cars at least five or six times, and i always come back. its the best there is, and its greater than stock. its ideal for forced induction, and its cheap to do. i can imagine this swap would be even more devestating with a redrilled cam gear.

248/248 is something im going to look at again with my current setup on the manuel car. (redrilled cam gear, intake manifold, SAFC, 3in exhaust, and dc sports header) it doesnt do any good in the auto, the loss in mid and low end isnt worth it. ive seen a dyno of 248/232 vs 248/248 and the difference in top end is something like 2hp, but the difference in midrange is 6 peak hp and all kinds of torque.....

Modified by DjPantsSpecR at 7:27 PM 8/30/2006
Modified by DjPantsSpecR at 7:30 PM 8/30/2006


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Postby sidewards » Sun Jan 08, 2006 4:53 pm

So you like the 248 intake and the 232 exhaust? To get a 248 intake don't you have to move the pin on an exhaust cam?

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Postby DjPantsSpecR » Mon Jan 09, 2006 12:10 pm

248/232 is the most worth doing is what i'm saying

all you have to do to get a 248 to work is rotate it CCW 4 teeth, or two pots on the chain.

its well known that a 248 on the intake side will be off by a certain amount of degrees, the actual amount escapes me, but it is significant, so i wanted to try as many combinations as possible to find the best set up without adjustable cam gears.

i'm actually liking 248/240 a lot better. 248/232 is still my favorite, and the butt dyno is also a huge fan of it too.

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Postby dickie » Mon Jan 09, 2006 1:09 pm

thanks for the info djpants, way to do our homework for us

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Postby InsanityInc » Mon Jan 09, 2006 1:57 pm

Well, my suggestion would be to use 248/248 with the proper stock LCA, or possibly even wider. The main part of bigger cams that hurts your low-end is the overlap. Now, then you'd say: Why bother running 248/248 with a wider LCA when I can just run 248/232 with the same overlap without cam gears?

While at first it may seem the same, it isn't, and 248/248 with a wider LCA is better for your top end. This is because in order to widen the LCA to reduce the overlap and keep the cams installed straight up, you not only have to advance the exhaust cam, but you also retard the intake cam. Now, SOME overlap is important, and with the 248/248 you have the same amount of overlap, AND you have a later intake closing than you do with the stock LCA and a 248/232, even though both have the same overlap, and since your exhaust closing is the same, your exhaust opening will occur slightly earlier, which could be good or bad really, but probably won't affect a whole lot.

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Postby DjPantsSpecR » Mon Jan 09, 2006 2:21 pm

exactly, i'm just glad you wrote it so i didnt. good to get the ugly people back in my threads too

i did say earlier in the thread, and i know you know this, but for the benefit of anyone else, 248/248 is something i would look into if i had other top end power producing goods. if i had a header, an exhaust, maybe high comp and ITBs with some management i would look into cam gears to make 248/248 satisfactory. but if i had that kinda money i would jsut buy some 256s and gears. so i still agree entirely that as a tuning tool 248/248 might be a nice thing to have, just you need cam gears.

248/232 is the poor man's power producer, adn as i under stand its great for our KA-T boys. plus if you're a real 240sx owner chances are you decided you needed a few new motors and at least one of those is probably an S14, so you got potential lieing around somewhere.

Insanity, 240 cam on the exhaust side, how is the LCA affected? thats what i really wanna hear about. i swa how its affects the motor first hand, but i wanna know why. why does 240/240 behave like it does and why does 248/240 behave like it does based on the fact that the LCA and overlap on an intake cam on the exhaust side and the exhaust cam on the intake side shouldn't simply correct or account for each other.

discuss. and please i welcome any questions regarding any above cam swaps....

keepin it poor, real poor

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Postby sidewards » Mon Jan 09, 2006 4:11 pm

i'm still confused, so I a 248 exhaust cam and can keep my 232 intake? Can I run that straight up or do I have to fudge with the cam timing? btw thanks for the nice write up.

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Postby Vkoslak » Mon Jan 09, 2006 4:53 pm

nice!

I have 2 232 cams I took out of a 98 240sx (i put 240's in) so when I rebuild the de motor I have I can put SOHC pistons in and the 248/232 cams and it should be real sweet

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Postby DjPantsSpecR » Mon Jan 09, 2006 7:00 pm

absolutely it will, but now i'm getting to be a bigger and bigger fan of 248/240, and i'll have to test that on my manual car. but i'm quite sure 248/232 is still what i want. i was also going high-comp but i ran into a lot of money problems, and speeding tickets just happen to cost 142.00, so i couldnt throw down 352.00 for some 1mm over 89 E pistons.... sucks to be me

on my friends car i swapped his 248 for the intake cam, and i used a 232 intake cam on his exhaust side. a 232 intake cam was rotated 4 teeth to work as an exhaust cam. i always wonder how this affected the cam overlap due to what was discussed earler about the cams being off a certain number of degrees by the "rotate four teeth method" in my car i have a 232 exhaust cam on the exhaust side, so there is no modifcation necessary. this also leads us in the direction of two different cam swaps. which is better 248/232(intake) or 248/232(exhaust)... so make those checks payable to Chase Trogen

Sidewards, you're going to want to leave your exhaust cam where it is (i'm assuming you have an s14 motor right?) and you take an s13 exhaust cam and put it on the intake side of your motor. line the dot on the cam gear up to where it used to be then rotate it four full teeth counter clockwise. it will help to make a mental note of where the first lobe on the intake cam is before and after you take it all apart, it will be almost exactly the same. if you get lost, make sure it looks identical to the picture on the sticky at the top of this forum. please ask if you have anymore questions, as when i did this swap it was a few years back and people were still unclear as to how to make an exhaust cam work on the intake side. i ended up with 12 bent valves and zero running 240s.... these days a complete cam swap takes me about 15-20 minutes.

thank you folks for the kind words, i just want to help people who can barely afford to pay for the maintenance on a 240, let alone two 240s, make theirs a little more enjoyable

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Re: (DjPantsSpecR)

Postby s14 2510's » Tue Jan 10, 2006 9:15 am

[QUOTE=DjPantsSpecR] please ask if you have anymore questions, as when i did this swap it was a few years back and people were still unclear as to how to make an exhaust cam work on the intake side. i ended up with 12 bent valves and zero running 240s.... these days a complete cam swap takes me about 15-20 minutes.

I know whos swaping cams in my ka. I still have to give you that drive shaft even though I dont think it will do you any good. U need any other parts for a ka?

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Re: (DjPantsSpecR)

Postby InsanityInc » Tue Jan 10, 2006 11:30 am

Insanity, 240 cam on the exhaust side, how is the LCA affected? thats what i really wanna hear about. i swa how its affects the motor first hand, but i wanna know why. why does 240/240 behave like it does and why does 248/240 behave like it does based on the fact that the LCA and overlap on an intake cam on the exhaust side and the exhaust cam on the intake side shouldn't simply correct or account for each other.
Well, theoretically if you get the cam centerlines installed the same with the 240 or 232, then the LCA will be the same with both cam setups. However, I'm not sure how many degrees one chain link equates to, so it may not be possible to get the stock LCA with both cams. Though, considering the cams seem to travel in intervals of 8 degrees (232, 240, 248), that might mean something with regards to the number of degrees a cam link equates to .

Now, even though your LCA is the same (or roughly so), some factors will change between a 232 exhaust duration and a 240 exhaust duration. Since the increased duration (8 degrees) is split equally to the left and right halves of the lobe, all events are changed by 4 degrees, so here is what happens with a 240 cam as opposed to a 232 (assuming the same LCA):

4 degrees more overlapExhaust Closing occurs 4 degrees later (which results in the greater overlap)Exhaust Opening occurs 4 degrees sooner

So really the only noticable difference will be in the overlap, which can be good or bad. If you have a stock exhaust system, more overlap is almost assured to be bad, because you're probably going to get port reversion.

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Re: (DjPantsSpecR)

Postby guyaverage » Tue Jan 10, 2006 4:58 pm

Djpants, try 240/232. Its the one I liked best and is what I am currently running. I didnt like 248/232 as much as I like 240/232. 248/232 midrange is good, but to me it felt like 240/232 had an even better low end, without sacrificing any of the midrange the 248/232 gives. This is on my '93 vert automatic.

I havent tried 240/240 because I am short one 240 cam, but you made it sound like fun, and now I'm going to have to try it. Now I have to hunt down a 240 cam and spend money. Thanks a lot...
If you have a stock exhaust system, more overlap is almost assured to be bad, because you're probably going to get port reversion.
Exactly. That sentence should be required reading for anyone messing with cams.

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Re: my comments on 248/240 s13 cam swap (DjPantsSpecR)

Postby redpotatoes » Wed Jan 11, 2006 9:36 am

I own a S14 and I did the S13 exhaust cams swap. I have now 2x248 instead of 2x232 cams. My impressions on this change is a lost at low rpm but a gain starting at around ~5000. If the rpm would be ~500rpm more, this upgrade would make a much more noticable difference. I will try the 248/232 setup next spring. Probably the mid range will be better.

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Postby HKSdrift3r » Thu Jan 12, 2006 1:22 pm

sweet write up.. does any one know where i can the info on what models the cams come off of.

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Re: (HKSdrift3r)

Postby InsanityInc » Thu Jan 12, 2006 2:18 pm

HKSdrift3r wrote:sweet write up.. does any one know where i can the info on what models the cams come off of.
If the car has butterfly valves (91-most of 94), then it has the 240/248 cams. If it doesn't (late94+), then it has the 232/232 cams.

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Re: (guyaverage)

Postby DjPantsSpecR » Thu Jan 12, 2006 3:05 pm

thats what wanna try next, but i wanna try both the 232 intake and the 232 exhaust for the 240/232 swap. i wish i had spent more time with the automatic that i swapped the 248/232(intake) into. but thats not even a fair comparason due to one being a fully stripped manual and the other a full interior automatic. ive been working all week to prepare the slut to work again, so i can mess around

the other reason is because i traded my 232(intake) for a 240, and my other s14 motor (s14 2510s's motor) i dont want to open up just yet. dont worry phil, its still going to see boost, but not for a long while here. i have lots of all-motor to explore, so ive been borrowing the occasional part from it

if i can find time i'll swap to 240/232 from my 248/232 and give impressions, but i also have 500 miles of clutch break-in, so i dont know how hard im gonna go on her

thanks again folks

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Re: (DjPantsSpecR)

Postby Southeast240 » Tue Mar 21, 2006 5:05 pm

Ok, i am an idiot here...I have a 95 KA and a 98 KA. The 95 is blown-up so i am upping to the 98. The cams are both 232s? The 95 has dual timing chains, the 98 has only a single. the heads look slightly different under the valve covers and dont look like either cams will work on either head. Ok, so i am going to the junk yard this week to get some cams from 91-94 KA (240sx,Altima,mini-van,p/up).

Please answer.....

Is there a difference in auto vs. manual in the cams? Do i need to get both cams?Does it matter where i get the cams such as 240, Altima, Mini-van, p/up?The Ka i have now only has a single timing chain, will the older KAs all have dual or single? If its a dual chain gear cam, how do i make it work in my single chain system without chainging everything else over?

Sorry for stupid questions, but i cant afford another motor. Want to do this right. I am not sure what to look for in the junk yard and if other KAs will be sufficient for this as well.

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Postby DjPantsSpecR » Tue Mar 21, 2006 6:10 pm

i entirely forgot in 98 nissan switched to single row chain...

but you can still use an s13 cam. i would recommend if possible to just get the exhaust cam, and use that as intake.

no difference in auto or manuel cams

you have to get the cams from a 240, you can use s14 or s13 cams but the s13 exhaust is highly recommended

all KAs prior to 98 have double row chain, you only need to change how you install the new cam you get. 98 intake cams are pinned differently so when they are in the correct position at tdc the dowel pin is at the 12 o'clock position. You can easily figure out how to put your single row cam gear on the s13 cam, and how to time it properly using the last page of the jim wolf technology cam instalation guide.

however, the cams on all s14s are 232/232 so your 95 cams will be the same except the pin position

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Re: (DjPantsSpecR)

Postby Southeast240 » Wed Mar 22, 2006 3:33 pm

Thanks so much for the info, this is a big help! You are essential to the KA community DJPantsSpecR!!!

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Postby DjPantsSpecR » Wed Mar 22, 2006 7:57 pm

from the looks of it, it meaning the jim wolf technology cam install page, it looks like to install the s13 exhaust cam as an intake cam in your 98 motor, you have to rotate the single row cam gear counterclockwise EIGHT total teeth.

now, this is going off the fact that the 98 intake cam has the dowel pin at 12 oclock when the first lobe is pointed away from the exhaust cam's lobe. Double row chains have the dowel pin rotated CCW 4 teeth when the 1st lobe is in the same position. So to get it to this "stock double row" position, you need to rotate the cam gear CCW four teeth first

the JWT guide will show you have to install a double row chain cam in your single row motor, but only the intake cam. to install a double row exhaust cam on the intake side of your motor you have to rotate the timing gear an ADDITIONAL 4 teeth CCW

so from your stock position, put the cam in the correct position, you will then need to rotate the cam gear counterclockwise 8 total teeth for the dowel pin to line up in the slot of the gear. Then torque it down.

be very careful, dont get in over your head, and dont blame me if you bend valves. Take a picture of your motor at TDC, and when you put everything back together, make sure the cam lobe positions look identical, then crank it over by hand, and you should be straight.

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Re: (DjPantsSpecR)

Postby struckinc » Mon Apr 10, 2006 2:51 pm

what would be the best combo for a s13 with intake, header, and 2.5 in exhaust? still 248/232? so i would my exhaust cam on my intake side and use an s14 exhaust on my exhaust side? i have 2 sets of s13 cams and 1 set of s14 cams....i am trying to figure out the best setup for my s13 and s14 with intake and catback exhaust..i am pretty sure from reading yall that i am going with the 248/232 on his s14 but would that combo work to my benefit for the s13?

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Postby DjPantsSpecR » Mon Apr 10, 2006 4:35 pm

yep, the best for what you want is probably 248/232 with both being exhaust cams

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Postby Guardians91240SX » Mon Apr 10, 2006 6:11 pm

But why only Exhaust cams, what is the down side to using an intake cam for both intake and exhaust, anyone ?

-Mike

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Re: (DjPantsSpecR)

Postby struckinc » Tue Apr 11, 2006 12:21 pm

i cant jsut use his intake cam for my exhaust? just align the cams and then rotate the gear to match the notch? what is the difference between the intake and exhaust cams on the s14?


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Postby DjPantsSpecR » Tue Apr 11, 2006 3:43 pm

using the 232 intake cam as your exhaust cam is doable, and ive done it. The 248 intake is already something like 2.5 degrees advanced farther than stock (from the centerline), and if you use a 232 intake as an exhaust cam it will be off by 2.5 degrees as well.

this causes an undesired amount of overlap. i obviously havent done any of the math, im just sayin from personal experience i dont like it. It might even offset the cam centerlines back to stock, id have to think about it, but i like the 232 exhaust cam for the exhaust side.

when ever you use your rotate method, make sure to rotate four teeth, because you could make a mistake if you simply just put the gear where the notch was.

I like 248/232, but i want to go back to some 248/248 action, but with re-drilled cam gears drill ala JWT. I dont think i can come up with any time this week, but ill also have to try 240/232 t add to my section

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Re: (DjPantsSpecR)

Postby tloof » Thu Apr 13, 2006 3:22 pm

If you take note of the cam specs in my post "KA24DE Cam Specifications" you will notice that EVERY cam combination that Nissan has ever used always opens the intake valve at 1 deg after TDC, and closes the exhaust valve anywhere from 4 deg to 8 deg after TDC depending on the duration of the exhaust cam. This means that Nissan never uses anything more than 7 deg or less than 3 deg of total valve overlap.

Now, the cam drive & driven sprockets each have 19 teeth on them, and the crankshaft drive sprocket has 18 teeth with 36 teeth on the driven sprocket up on the head. This means every tooth rotation of the cam sprocket = 18.95 deg, and every tooth rotation of the driven 36 tooth sprocket = 10 deg. The drive dowel pin is located in line with the 1st cam lobe on all of the '91-'97 intake cams and when installed in the head this pin is supposed to be positioned in the 10 o'clock position. The later '98 up intake cams had the drive dowel pin relocated 75.8 deg clockwise from the 1st cam lobe so that when they are installed in the head the pin is positioned in the 12 o'clock position which is the same location as the exhaust cam pin is positioned in when installed in the head. Now the actual pin location in relation to the 1st cam lobe on all exhaust cams is not the same as it is on any of the intake cams (whether early or late versions), but rather it is 75.8 deg counterclockwise from the 1st lobe (this is true for all years of the exhaust cams be it '91-'04 models). Thus when using an exhaust cam in place of an intake cam you have to rotate it 151.6 deg (which is 8 teeth on the drive sprocket) in relation to where it sits when mounted on the exhaust side. Of course you all keep hearing on this site that it must be rotated 4 teeth when using the exhaust cam as an intake cam, but that is actually refering to where the pin is to be located in relation to the normal 10 o'clock position that the '91-'97 intake cam pin is positioned when installed in the head. The smarter & safer way to install it is to mark the 8th tooth clockwise from the pin location on the drive sprocket, and then line that mark up with the colored link on the intake side of the drive chain which will then cause the exhaust cam to have to be rotated counterclockwise 151.6 deg in order to position the actual drive pin on this cam in the 7 o'clock position when installed in the intake side of the head. If a '91-'97 intake cam were to be used as an exhaust cam, then just the opposite is required...that means that the drive sprocket (& intake cam) should be rotated clockwise 151.6 deg (or 8 teeth) so that the actual drive pin on the intake cam will be located in the 2 o'clock position when installed in the exhaust side of the head (this by the way will line the drive pin itself up with the colored link on the exhaust side of the drive chain). Note: that if a '98 up intake cam is used as an exhaust cam, then the intake cam drive pin will end up having to be located in the 5 o'clock position when installed in the exhaust side of the head since they have the pin relocated 75.8 degree clockwise on the cam itself.

I'll have to go into this a little bit farther another day, but it should be kept in mind that the teeth on the drive sprockets don't actually line up exactly with the pin on the cam itself as I recall, thus there is a slight difference in cam timing when an exhaust cam is used as an intake cam (or vice versa...an intake cam used as an exhaust cam). The 2.5 degree difference mentioned earlier sounds about right. The thing is, when a 248 deg exhaust cam is used (in the exhaust position) it gives a 7 deg overlap regardless of which intake cam is used, and a 232 deg exhaust cam (when used in the exhaust position) will give a 4 deg overlap regardless of which intake cam is used. But if a 248 deg exhaust cam is used as an intake cam, then it will reduce the overlap by the 2.5 deg (the amount mentioned when using the 4 tooth rotation method) which when used with a 232 deg exhaust cam would then give only a 0.5 deg overlap and the intake would open 3.5 deg after TDC instead of the 1 deg after TDC that Nissan uses on EVERY KA24DE combination...not a very good setup to say the least. I personally feel that it is better to use a 240 deg intake cam in the intake position with a 232 deg exhaust cam in the exhaust position. This combo will open the intake valve at the proper 1 deg after TDC point, as well as close the exhaust valve at 4 deg after TDC thereby maintaining the proper 3 deg overlap (which is best for low to midrange power). By getting the intake valve open 2.5 deg sooner than the 248 deg cam, it will actually still help out the top end range even though it has 8 deg less total duration (after all the intake valve is being closed at 61 deg after BDC with the 240 deg cam vs 71.5 deg after BDC with the 248 deg cam, which is a bit extreem for closing the intake in my opinion).

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Re: (tloof)

Postby crzycav86 » Fri Apr 14, 2006 6:34 am

Excellent post tloof.


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Postby DjPantsSpecR » Fri Apr 14, 2006 11:14 am

i agree, very good information all available in one place. I can honestly say it has had me doing a little researching today.

earlier i was ambitious, and i was going to swap my 248/232 automatic for 240/232. And then in turn i would redrill a cam gear so i could use that 248 on my other car and try a 248/248 swap, but with closer to stock overlap. Unfortunately i ran into some things that made me much less ambitions

our value of 2.5 is from somewhere, but everyone else generally agrees that a 248 cam on the intake side is retarded 1.7 degrees. this is half of what we were thinking, which probably has something to do with the centerline relationship.

a dyno i spent an hour searching for earlier compares 248/232, 248/248, 248/248 with 5 degrees separation, and 232/232. it is on fresh alloy and is posted by a member with a blank space for a name. either way the summary of his results were 248/232 nets 4 additional whp from 2k-6k, where 248/248 with five degrees fo separation gained 2 whp over this from 6k-6.5k. its really too bad there was no mention of 240/232.... but this analysis and dyno chart is from two years ago.

the moral of the story is: 248 on the intake side is retarded 1.7 degrees. with a homebrew-redrill cam gear, or i guess a real live JWT gear, you can advance this by 2.5 degrees for a total of .8 degrees advance.

this looks to be much more acceptable, and would put a factory cam .8 degrees away from the nismo 248 intake cam, for much cheaper.

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Re: 240/232 Cam Combo

Postby tloof » Fri Apr 14, 2006 1:20 pm

I installed a 240 deg intake cam from a '97 Altima this past weekend in the KA24DE that I'm building up for my 720 pickup (I'm using a Frontier bottom end with a '95 240SX head & intake) along with the S14 232 deg exhaust cam, so my valve overlap will be 3 deg with the intake opening 1 deg after TDC and the exhaust closing 4 deg after TDC. This should maximize my low to mid range power for use in a truck while still providing a fairly decent upper end power range as well (I don't think using the 248 deg exhaust cam for use as an intake cam will be as good in a truck installation!).

I do need to go back and measure my cam to bucket shim clearances this weekend, so i will look closer at all of my cams & try to determine if the 248 deg exhaust cam is retarded by 1.7 deg when used as an intake cam via the 4 tooth rotation method with the stock drive sprocket. If indeed that this is the case, then the 248 deg cam would open 0.7 deg before TDC and close 67.3 deg after BDC giving a 4.7 degree valve overlap when used with a 232 deg exhaust cam. Typically the stock 240 deg intake cam closes at 61 deg after BDC, so using the 248 deg cam increases that by another 6.3 deg. Perhaps that's not so bad and might be a good combination afterall, but I suspect that using a 240 deg intake cam will still be better for the low to midrange power while still providing good upper end power as well, but who knows for sure??

The 4 whp that the 248/232 combo makes over the 232/232 combo is probably only better by about 1 hp over the 240/232 combo, but the 240/232 will have slightly more mid range torque so will probably be just barely faster in acceleration and feel better around town overall. The 248/248 combo is totally useless, and will fall flat on its face down low and will be trying to play catch up in a drag race against any vehicle with the 240/232 or 248/232 combo. In the end it is really a choice between the 240/232 or 248/232 that will be the best setup, with trucks & Altimas probably favoring the 240/232 combo, and the 240SX's using the 248/232 combo since they are slightly lighter in overall vehicle weight!!

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Postby DjPantsSpecR » Fri Apr 14, 2006 1:44 pm

sorry i must not have been clear, this 4whp loss from 2-6k is when comparing the 248/248 (but with the poster says is 5 degrees of seperation, the highest top end power producer) to 248/232. where the only benefit of 248/248 +5 is a gain of two wheel horse at 6-6.5k.

everyone who has ever written anything about 240/232 is very satisfied with it, however, you rarely read anything written about it, so the amount of people doing this is very low, but like i said i would have really liked to switch my heavy automatic hatch to 240/232 from 248/232 and i will be able to post yet another comparo.


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