I believe that it would be a .5 degree advancement. IMO still not good enough for high rev and HP. The majority of guys that are making power with even stock s13 KA's retard between 3~5degress from stock duration on INT to increase power in the higher RPM (using the stock 240/248). It follows alot of the same principles like honda Vtech to bring overlap closer and lower within the first stroke to promote healthier power at higher RPM. A .5 degree advancement is still not as good as stock and I have yet to see a dyno that promotes a larger amount of HP at that degree.Granted the engine will provide a healthy torque range, but HP will still be something that needs to be seen.struckinc wrote:yes. using the 4 tooth method on the intake...or making your own gear...or you can use the 92-95 altima exhaust cam and after the adjustment you timing will only be off about .5 deg...that is the setup i am running
I'm positive. I saw a dyno a few months back with an s13KA24de 92 stock 240/248 cam setup using a jim wolf technology cam gear on INT. I am not quite sure how far the cam was retarded but it was retarded (assuming if JWT it was 7 degrees retarded maybe?). Fuel mixture at low throttle was also leaned out at partuicular parts of the rpm range and a wide band O2 was used. Pretty much stock internals with intake, advanced timing, and header was pushing roughly 180HP at the wheels and KNOCK settings didn't raise more than a point from what the SAFC was regestering on the monitor.If you look at the 248/248 nismo cams the reason why infact it doesn't make power is because INT is advanced further than what stock is. But if you look at 232/232 they make good power, so now the realative answer to that is because of the actual cam placement of 248 onto INT.I also do realize the larger the duration the cam onto INT the more retarded the cam will need to be in order for the engine to run or IDLE properlly. Retarding the cam will only allow the valve to open later into stroke one creating a stronger vacuum. There is no direct equation or calculation for cam placement other than what I do know nissan engines with a simalar rod/stroke ratio tuners have normally chosen to back off cams.As far as best mean torque the engine will do fine achieving a high torque band with a cam slightly advanced, but it shows small returns for HP output.Years ago I use to own a z24I, it came with an adjustable timing gear that would advance or retard +/- 3degrees. I did notice that low end torque drops a tad retarding the cam, but high end acceleration was much better for the most part. It felt more like an Honda engine accelerating as if it wanted to keep reving faster.If I also remember correctly there was this 19 year old named Tre that was at Zilvia, and in the Nissan Pacific forums. I found his method of tuning to be somewhat awkward and I dogged the kid pretty bad in the forums. He happen to retard the exhaust and his intake using the stock cams and JWT cam gears. I was knocking on him for advancing the distributor fully. I was ragging on him for raising the EGT and splitting the timing gap too far also disturbing his idle, and since the engines are also prone to knock he was running piss loads of fuel. He claimed that knock wasn't so bad either. In the end of the arguement he showed me his time slip for his stock block, damn youngster ran a 14.9sec 1/4mile or what is the equivlant to 205 hp at the crank. I still don't recomend his cam placement or timing confuiguration though.DjPantsSpecR wrote:wait, vinnie, really?
I think what you wrote is confusing me, you put that guys are retarding their intake cams to make top end by retarding them. this is kinda counter-intuitive to everything ive learned.
are you sure you meant 3-5 degrees of retard?
BINGO!The inertia that is created increases atomization! The only reason why the KA cams are set to there position is just for smog and fuel economy, but nobody to date has ever cared to clarify the missing 15+ HP you can get from stock cams properlly setting them within the safety margin of 3~5%degrees retarded from stock. In other words when I try to express advanced cam placement as best mean torque you can see it on any KA dyno graph where as the KA usually produces more torque than HP (well atleast bone stock), I would say that Nissan has already determined that cam placement is already to far advanced, but was set for proper fuel economy.Advancing the cam past the recomended stock spec will also decrease fuel economy since in the long run actual engine VE's and AE's drop from stock spec and too much overlap occurs when the engine is producing power for load.In many cases Nissan now uses CVT to position cams, just as Honda uses I-vtec. Vtec when it was first developed only allowed for a cam to be retarded in order to increase power at higher RPM. Now I-vtec or Nissan's CVT can now adjust cams either to advance or retard depending on driver habits to conserve fuel.So when people ask me if the HOT CAM setups are great I always say no. Just because they don't make the kind of power that they could be making if set to the right degree that the engine likes. Again people also need to remember that there is no formula or calculation for setting a cam to make the most power withing the first stroke, so it sucks when you have to hit the dynop numerous times to reset a cam position. One of the reasons why like my stockers (240/248).InsanityInc wrote:Retarding the intake cam makes more high end power because it extends the closing of the intake valve further past BDC, which allows for air with more inertia (at higher RPM, your intake air has more inertia) to create a supercharging effect in the cylinder. It's the same reason why more duration on the intake is desirable. But, don't retard it too far or you'll screw your intake opening up.
Advancing the intake cam is usually doubly bad because you increase overlap and move intake closing closer to BDC, which will make the car usually run like crap overall.
Just to let you know the set up that is being used.240/248 cams onto s13 ka24de. INT is retarded 7degrees timing is advanced at the distributor 3 degrees.That was the set up that was used on the KA24de that was dynoed.That also happen to be TRE's set up with out the exception of fully advancing the distributor, which is what I highly disagree with (raised EGT higher exhaust levels it would need iridium plugs).Fuel curve also needs to be changed with an SAFC or ECU tune, fuel ratio between 12.7:1~13.4:1.DjPantsSpecR wrote:im eager to try 240/248 set to stock with -5 adn -2.5 degrees of retard, however. you should try 248(+5)/248(-2.5) as a compareson as well, before you can say the "hot cam setups" are bogus.
7 degrees is pretty excessive, especially considering you're already running a 248 intake cam. On a stock manifold, you're just going to put your powerband beyond what the rest of the engine could ever hope to do. I'd recommend a total retard of 4-5 degrees at the most. You likely would have noticed that the car started performing a lot better had you taken it above 3k. That much retard will make it run similarly to putting a huge cam in the car.DjPantsSpecR wrote:okay, well youg ot me all excited, so as soon as i read this i ran home and redrilled a gear for 5 degrees of retard. this is on a 248 intake cam, so its already 1.8 degrees before tdc, so it should sit around 6.7 retarded. this is paired with an exhaust (248) that i left 2.5 degrees retarded.
the car idled fine, and it sounded entirely different. however when i went to drive it, there was clearly something wrong. there was no response anywhere and power was clearly very very weak. i didnt take it past 3k, because obviously there was a porblem.
so i set it back to stock. i guess if i were going to get this to work i would want 2.5 degrees of retard on the intake cam and probably 2.5 degrees of advance on the exhaust cam.
so clearly, this 7 degrees retarded idea doesnt work on a 248 intake. at least with minimal exhaust retard. i'll have to wait until another time to do all the cam math to see what exactly is happening, but clearly this isnt for 248/248 users.
im eager to try 240/248 set to stock with -5 adn -2.5 degrees of retard, however. you should try 248(+5)/248(-2.5) as a compareson as well, before you can say the "hot cam setups" are bogus.
No you are not understanding. The degree from one tooth to the other is about 18.9Degrees. No matter what cam adjustments you make you can't go passed 12 degrees (retarded) from stock. It also isn't advised to retard more than 5 degrees for streetable engine setup's.struckinc wrote: each tooth on the cam gears are equivalent to 4.75 deg right? so to do this people using the 4 tooth method should actually be going back 5 teeth. am i understanding this correctly or no..just trying to be sure
I'm assuming the graph showing more HP is the 232/232 (nothing is properlly labelled).It seems to be a trade off in the overlap of the 248's. Torque is still represented as making more power on a set of 248's. Just looks like there needs to be a little seperation in the overlap to make more power.I wouldn't be surprised if a 1 or 2 degree retard on intake would extend HP...DjPantsSpecR wrote:just so happens someone posted this today. entirely stock KA. 232/232 vs 248/248.
Why is it that 2 torque curves almost ride side by side each other, while one drops off significantly????That shows a bit of some confuson for myself since when you look at the NISMO chart torque is significantly less using the 248???Where was the cam placement on that specific dyno????DjPantsSpecR wrote:no, the one that made the most horsepower is the 248 obviously. its nearly identical to the dyno you posted, it loses low end before 4k and then its greater for the rest of the rev range.
and after you shift youre never below 4k for a redline shift.