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valves staying open longer would mean more potential for more energy but you are asking about duration as it is not related to lift and valve motion.

So for a given lift and head flow characteristics like an OEM honda head, under the valve motion model to keep jerk as low as possible and everything working great, duration is what it has to be.

We also do not split duration and intake and exhaust together is what makes the whole thing work.

Porsche Gt3, porsche cup engines, M3 racing engines etc etc use close to 290 duration and we only go that high on lifts beyond 600 if the valve motion can handle it.

One of the reasons behind this is harmonics but from a frequency point of view.

The truth is that you can put anything on these lobes and the engine might run and might even make some power but doing it the right way and saving tensioners on the way and not breaking chains or cam cores or engines or heads, or rollers, means that you have to follow all rules and design with honda oem valve motion is mind which is based on the geometry and nothing else.. The cams do not know what head you are using, or fuel or compression, only they tell the valves is how to open and close and the rest is HP somehow.


Let's assume at 6000 RPM, you are using a spring with 27000 cycle per minute natural frequency its around the 9th harmonic.. as RPM goes up, harmonic order goes down. At 9000 RPM, if you do not have control of these things, specs do not matter.

That is why there is a great aftermarket tensioner market because noone in their right mind will take the time to expain why to an audience full of doubters, haters and for the most part not serious about performance.

Email me at svmcams.com if you want to talk about this more, not because I want to sell you a set of cams, but to help you understand when I have time to reply.

As long as RPM is kept under 7000 rpm on normal cars, bad design habits will not show themselves as much... the higher the RPM the greater the need for precise opening and closing of the valve with velocities and accelerations all working the same way on each cylinder and minimum deflection at high rpm, all these things make a difference, a huge difference.
I would like to learn more also, I don't know much about camshafts. I'm finding it difficult to choose cams for my rotrex K24 build.
 

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More difficult for me, looking for cams for my K20A jrsc setup.
 

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Curious on something.

Say I have a stock block TSX with a stock K20 head vs a stock block TSX with a CNC K20 head, can I run a bigger camshaft with the CNC head than I can with the stock head because of the increased flow of the head?

Supporting mods on the engine the same between the two.
 

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"Big cams" is a pretty generic description, but I think the simplest answer to your question is big cams are going to shift your power band rightward (i.e. power will be made higher in the RPM range). On a stock TSX short block this is dangerous given the limitations of the OEM pistons and rods. Yes the CNC ported head will support the increased lift on the bigger cam, but the rest of the motor won't. The reason people run high cr pistons with big cams is because the increased TQ fills out the midrange dip in power with big cams (again, due to a rightward shift in the powerband).

The more complex answer depends on "how big" of cams and where you're going to set your rev limit. Big cam could also mean big lift (again, this would be a no no with TSX pistons) or longer duration (then header, cylinder head, and intake manifold become much more important).
 

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The cams I am referring too are Drag Cartel 3.2 cams. Not huge cams. Rev limit is 8500rpm.
My gut says the motor with the ported head will make more power and the curves will separate around 4000 rpm. I bet the motor with the stock TSX head won't make power past 7800 rpm.

I thought you decided to go with a built short block...?
 

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My gut says the motor with the ported head will make more power and the curves will separate around 4000 rpm. I bet the motor with the stock TSX head won't make power past 7800 rpm.

I thought you decided to go with a built short block...?
I did, just 11.1cr though just in case I wanted to boost it.

I saw a stock TSX block with a 4p 156 head and drag cartel 2.2 cams stop making power before 8k I believe. IIRC it was in the posted in the stock block thread a few months back.

I think too much for my own good sometimes lol
 

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I did, just 11.1cr though just in case I wanted to boost it.

I saw a stock TSX block with a 4p 156 head and drag cartel 2.2 cams stop making power before 8k I believe. IIRC it was in the posted in the stock block thread a few months back.

I think too much for my own good sometimes lol
Yeah I remember that post, but I would blame the cams not the head for that result.

FWIW, I'm thinking of doing the same thing with my 2.4...quality aftermarket rods and ~11.1 cr just so I don't have a broken OEM piston or rod explode on a mis-shift and bend all the expensive valves in my cnc head.
 

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Yeah I remember that post, but I would blame the cams not the head for that result.

FWIW, I'm thinking of doing the same thing with my 2.4...quality aftermarket rods and ~11.1 cr just so I don't have a broken OEM piston or rod explode on a mis-shift and bend all the expensive valves in my cnc head.
I'm using Manley H-beam rods in my motor, picking a rod was the biggest headache of the entire build for me. From everything I've researched, these rods are pretty good. When I checked 4piston's website, they seem to use these for their builds on their short blocks so that helped a lot in choosing them.

Another thing, I have quite a bit of P2V clearance in my motor, around .074" at max 30VTC.

What cams will you be using in this 2.4 build?

I was worried about the DC 3.2 cams having too much overlap for the 11.1cr, meaning shitty idle quality and bad drivability down low. :scared:
 

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I'm still planning to use the IPS KME-11 cams. With stock compression, I think 270-280 hp with a ported head is realistic based on the data Greg (aka 6spd_EK) has posted. The lower compression will decrease torque a bit and *hopefully* result in better drivability in 1st and 2nd gear. Otherwise I don't see the point in a six speed transmission if you're only able to use six gears...lol
 

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hey guys ive got Drag Cartel DICs and rbc in the mail...next im gonna order hks hi power exhaust and rdx injectors,,,,already have kpro, intake, headers, motor mounts, flywheel....want to know if there is anything else I should consider....possibly valve train upgrade as well just to be safe?
 

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May I ask a quick question about using high lift cams on a K20 i-VTEC race engine.....I'm pretty unfamiliar with building these i-VTEC engines although
I've built many N/A and turbo engines using fixed cam timing/solid lifters. With the fixed cam timing engines I'd always check valve to piston pocket clearance at a specific timing point of that cam using clay and usually have to machine the pocket of the piston to gain enough clearance. But of course that clearance is only valid at that specific cam/valve lift timing position, which is not a problem with those engines as you time in the cams once and that's it - fixed.
But...How does one check that figure on the K20 when the VVT cam timing can vary so much ?

I want to get more power out of a 2 litre K20, hence I'll be buying new pistons and cams, but can I be sure the cam/piston combination I choose will allow sufficient clearance?

Is there any way of "pegging" back the VVT pulleys to limit that timing range? I'll be running a Pectel SQ6 ECU to control VVT and from what I can see on the current map, the timing figures vary massively. If I change the cams, then I assume I'll need to re-map and risk valve piston contact.

If anyone has any experience of addressing these issues any help or guidance would be greatly appreciated.
 

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What I have :

K24A2 block
K20Z1 head STOCK port with supertech nitrated valves, springs H1021D (92) + retainers

I need cams for N/A street application , looking to hit 280-300 WHP with supporting mods.

What cams would you recommend.
 

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What I have :

K24A2 block
K20Z1 head STOCK port with supertech nitrated valves, springs H1021D (92) + retainers

I need cams for N/A street application , looking to hit 280-300 WHP with supporting mods.

What cams would you recommend.
With a stock block, you will need a professionally ported head, upgraded fuel system with proper fuel, and stage 3 cams to reach ~280 hp NA. You will also need a ported RRC or a carefully chosen aftermarket intake manifold. Even then, your goal HP is unlikely on a stock short block.

There is a reason you don't see any dyno graphs floating around with stock blocks making 280-300 hp NA.

Without a ported head, I think you will max out around 270 HP. Even then, that will be a fairly steep rise of the HP curve without much area under it.
 

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Were stock heads even up to 270? Man that seems high, but I haven't followed NA builds that much, let alone within the past 2 years.
 

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Were stock heads even up to 270? Man that seems high, but I haven't followed NA builds that much, let alone within the past 2 years.
I know of one person with a freshly built K24a2 with 2011 TSX pistons, upgraded fuel system, k20a2 head, and prayoonto stage 3 cams who made 268-272.
 

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damn, not bad at all, almost makes me wonder what a crv head would do with some vtec killer cams up top.
 

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Trying to ascertain if there is an point getting cams, and what options exist.

K24A3 with stock parts, except for NR RL5 pistons (projected bump to 11.13:1 comp) K-Tuned ECU / mapping

I see Skunk stage2 and Drag Cartel - which seems to be the price range - 650ish - to 950ish.

Someone said '06 TSX intake cam in one thread.

Motor will stay stock otherwise, and it's going in a 2000lb mid engine setup. More interested in mid range torque than upper limit HP push.

Any input from experience on here?
 
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