[Jim Swantko]

I've been considering going with a 272 exhaust cam and was just curious who out there is using them - and what their impressions are.

BTW - the car currently has a 74 turbo - but may go a bit larger.

Thanks
Jim

 

[Mark Conte]

Sorry I dont have any info to add, but I would like to add a question. I've heard the stock cams flow about 74lb/min which i think is approx 675ish rwhp. Does anyone know how much the HKS 264, 272s, JUN, or Crowers flow? (number wise) I was also considering the 264/272 combo. No one seems to know how much clearance we have, lift wise, before the 2JZ becomes an interference engine....Jim, you have any imput on that?

thanks,
Mark

 

[rocked]

272s HKS make the motor interference...264s are fine..I'm going with 264s to make 800rwhp..I don't want to brake out a timing belt and slam a valve....not fun...

 

[Mark Conte]

Oh really, what about JUN? the HKS 264s have a 9.25mm lift, and the 272s have a 9.35mm lift, AFAIK the JUN 264s and 272s both have a 9.3mm lift.

 

[Ryan23]

272s HKS make the motor interference...264s are fine..I'm going with 264s to make 800rwhp..I don't want to brake out a timing belt and slam a valve....not fun...

Incorrect. 272's do not make a 2JZ interference. Anything over 10mm will though. The 272 have only .1 mm more lift than the 264's, 9.25 vs 9.35.

http://www.moreboost.org/cams.htm

Ryan

 

[Mark Conte]

Thanks for clearing that up Ryan. I've looked on moreboost.org but I never saw a specific number that said anything past this will cause interference.

 

[Ryan23]

Thanks for clearing that up Ryan. I've looked on moreboost.org but I never saw a specific number that said anything past this will cause interference.

Bottom of the page linked above, talks about the Crower cams and the lift at which it becomes an inteference..

Ryan

 

[Mark Conte]

Yeah, I saw that it made them interference, I just didn't know if 10mm was the minimum or that the Crowers happened to be over the minimum...to rephrase: would 9.9mm lift cause interference?

 

[Ryan23]

Yeah, I saw that it made them interference, I just didn't know if 10mm was the minimum or that the Crowers happened to be over the minimum...to rephrase: would 9.9mm lift cause interference?

I don't know if 9.9mm would or not, I would probably clay the head at that point rather than rely on what someone else thought. What I do know, is that the 264/272's (cams in this post) will not cause it to be interference. Considering that they have pushed many a MKIV up over 900 RWHP, that's good enough for me

Ryan

 

[rocked]

technically if you had oversized valves you would have an interference with those cams...that's why I was under the impression it did.

 

[Ryan23]

technically if you had oversized valves you would have an interference with those cams...that's why I was under the impression it did.

As I said, I would have to clay the head to be sure, but with a lift difference of just .10mm or .003 of an inch, I find it very hard to believe that 264 would not be intereference and 272's would.

Ryan

 

[v8huntr]

i had bigger valves in my motor, which was about 2mm over stock. i also had 272 cams with bigger valves and didn't have any problem using them.

 

[Mark Conte]

Well the problem wont occur until the timing belt breaks anyways.

I just want to be safe, and in case that happens, dont want to lose my engine.

 

[rocked]

From what I've been told by PHR etc. however not all people held this as true...1mm oversized valves will cause the motor to be interference on stock pistons...aftermarket pistons are cleared for it. Trying to confirm on my own...

 

[Mark Conte]

weird. How would aftermarket pistons with potentially higher compression have more clearance than stock? Very interesting.

 

[suprattnsa]

Back to the original topic please

I too am interested in the staggered cam set up. However, due to my curiousity, I went ahead and ordered the 264i./272e. combo anyway and will be installing these cams by the beginning of Feb. I also have a 74mm turbo so this should be interesting!

 

[Krister]

What's the advantage in using different duration cams in exhaust vs intake side?

 

[Ryan23]

From what I've been told by PHR etc. however not all people held this as true...1mm oversized valves will cause the motor to be interference on stock pistons...aftermarket pistons are cleared for it. Trying to confirm on my own...

weird. How would aftermarket pistons with potentially higher compression have more clearance than stock? Very interesting.

That sounds right, at least in theory. Aftermarket pistons could *potentially* have larger valve reliefs for the valves. Lift remaining the same, if the valve diameter exceeded the relief diameter (on a stock piston), I could see interference. However, not all aftermarket pistons are going to have larger reliefs. Also, on the second question, aftermarket pistons won't necessarily have *more* compression. They could be stock or lower than stock compression. The reason some people choose to upgrade the pistons for strength. For a street/strip car, I'm don't recommend swapping pistons...but on a full out race car, you betcha . Thermal cycling, on the drag car, is going to be a lot more abusive than what your daily driver sees. Hence, forged pistons for the race car....

Ryan

 

[BLACKMKIV]

Anyone use 264s or the 264/272 combo on stock turbos? What kinda increase would I see?

 

[Mark Conte]

Ryan, makes sense, yeah I know a lot of people swap pistons for strength, its just that time and time again, the pistons have proven their weight in gold. They are incredibly strong, as I'm sure you know, but yeah I agree, better to go aftermarket when a racing application, if for nothing else the weight savings. If I go to aftermarket pistons, then I'll probably bump the compression for a power and spool gain.

Blackmkiv, there are a few threads that talk about using cams on bpu setups, I think the general consensus is that they help, but there will be more lag (especially if you use 272s)