Comp cams xe268h for 318
I have a question for the ones of you who say the summit (crane) or whatever it is grind is trash. And let me start by saying that I have great respect for you and acknowledge your experience and knowledge. But have you ever actually ran or drove a engine with the cam or you just saying its trash based on the numbers? Because I have read at least 10 or more reviews with ppl completely happy with it summits website has 3. One of them is a 4x4 360 he even commented on how great the low end torque was. So I'm curious have you had a bad experience with it or you just saying its trash based on the numbers on the paper? I get it the ramp like 74 is not ideal for cylinder pressure the 112 lobe separation doesn't help bottom end either but surely it cant be that bad cause summit still makes and sells these things after all these years. There is one video of a guy running it sounds pretty stout to me you can see the car squat at about 30mph and sounds like he is spinning. So like aj said less than 30mph its probably not gonna be set no 60ft records but I'm not racing this car it's a driver. So please let me know if you have any hands on experience with this(these) cam and again this is completely a respectful post.
I have never run it. It would never be on my radar.
Here is one more deathknell; The total time, in degrees, for all cam-timing events is 720*, plus the overlap. This cam has overlap of (278 +288)/2 less double the 114Lsa =55*.. So that totals 775 degrees. Now you subtract the intake plus exhaust from that and 209* is left over for compression plus power. If you install that cam at 108* to recover some cylinder pressure, this will subtract 113* of compression time, leaving just 96* for to extract power. 96 measely degrees and then the exhaust pops open and pow it all dumps into the headers, still burning, and with plenty of energy in it. And you paid for that energy, when you filled the tank. And now it's contributing to global warming.
With 2.76s, as a streeter,your engine might spend 99% of it's life below 65Mph, which in high gear is a tic over 2200rpm, and in second is a tic over 3200, and in first gear is 5400Rpm.
Now of that 99%, the bulk of it will be spent below 40Mph, which will be a tic under 1400 in Drive, a tic under 2000 in second, and about 3360 in low.
So riddle me this:
1)why would you put a 5500rpm cam into this combo. when the only time it will ever see that is for 1 or 2 seconds at the top of first gear, and for just 1% of it's life. And
2) in the mean time it is using gas like a junky on crack. And
3) the guy in the next lane with an identical car but with a stock cam, a 2800TC, and 3.55s is getting ready to show you his tailights, every single time he takes off, with a 2bbl yet; cuz his combo gets up on the pipe as soon as the tires break loose, and keeps it there to 40/45 mph, and then BAM! he shifts and clobbers you even worse, just when your car with the 6900cam, was getting to the power at 3700rpm.
The numbers rarely lie; they are usually best case
I can tell you exactly how too big that cam is for your combo; remember I said the compression plus power of the 6900 came out to 208*? Well
Wyrmrider says that cam is measured at .004, so if you actually measure it and find the durations for .006, so you can compare apples to apples, I'm guessing it would be around 275/282/114. and the math for that says comp+power~214*.. But even if I'm wrong and it's closer to 268/276/114, that still only maths out to 220* comp +power
Your combo wants about 240*, which I would split close to 124/116. Wait where have I seen those numbers before? Hyup the stock 360 2bbl cam. That will get you 17* more on the extraction or plus 17.2%, and plus 11* more compression or plus 9.7%, and 25less degrees of overlap which your combo cannnot possibly make use of anyway,and you can install that 360 cam closer to straight up.
This is a triple win for performance in your combo.
The only downside to the 360 2bbl cam is a total loss of the lumpy idle lope, which really is a just a byproduct of the overlap, which any SBM car that cannot spin the tires and with hiway gears will NEVER make use of more than once if at all, on the way to 65mph. That lumpy idle will cost your combo nothing but tuning troubles and dollars at the pump. And honestly, to hear that 55* you are gonna need to idle it right down, so you better have oil-pressure,and you better be able to tune it, cuz when you put it into gear, your lo-stall is gonna want to drag the engine down, maybe enough to stall it. And if not, then the hesitation that can come when you step on it might. It's just a poor situation. That cam will want to idle, in your combo, at maybe 700 plus rpm, and 55* don't lope much at that rpm. So forget about the lope.
And as someone else already said;
since you are sure to need both gears and a TC with just about any cam, you might as well start with gears and TC, and of those;the TC is the best bang for your bucks. It only takes a couple of hours to install it, and if you don't have the equipment and tools, just save up a lil more and hire somebody who does; it ain't rocket science. On a hoist it's bam-bam and done.
And finally , that cam is not trash.
It's only a bad choice for 2.76s, and a stock 1800ishTC; which the 6900 in an 8/1 teener,will only conspire to bring even lower.
I'm not trashing the cam, I'm only telling you that it will trash your current combo. A 6.1Dcr is pretty flipping low