Superrev kit for DE

[Kouks]

Will it make power on stock cams, and will it(the bottom end) hold up to spinning those rpms? What kind of Duration would you want to make power with this kit?

[PandaS14]

you've gotta give us more info man. Maybe a link to said parts etc...

[thekage]

umm yeah. More info.

From my research.. higher reving on the ka.. Forged internals.. bc the bottome end wont hold up much past 7k. Larger cams would def help.. springs and retainers from a CA will fit. That will help it rev higher... If you have a KIT in mind.. please share this info.

[Kouks]

http://www.boostdesigns.com sells a kit called the Super rev kit, it retails for 350.00 and comes with valvesprings and titanium retainers. Just wanted to get some feedback on what everyone else thinks. Im not a noob, just looking for an opinion.

The stock duration wouldnt make any real power past 5800, and even with a high duration cam like 280 I, 270 E, would the stock intake manifold make power with that set up on a N/A with bolt ons? Seems like with the long runners, it couldnt make any real power with that kit? Opinions, more questions?

[:: orion ::]

I'll bet the stock KA valvetrain can do 8000rpm easily...untouched. Cam-on-bucket is great for high RPM - No rockers to throw, less mass, more direct, etc...

So you don't need better valve springs unless you get a really high lift cam...which has been proven to give minimal gain anyway...KA cams have plenty of lift, they need more duration.

AND...the problem with revving high IS NOT THE HEAD/VALVETRAIN...it's the bottom end.

FYI...

- Brian

[Kouks]

So would you spin the stock bottom end to 8 thousand is question #1, and number 2, what would be required to spin....forged pistons, balanced shot-peened rods......Crank wouldnt need to be touched would it?

[:: orion ::]

You'd need less stroke IMO...so you would need a custom crank.

96mm of stroke and +7500rpm = pistons speeds over 4700ft/min...that's considered excessive, even with forged rods.

For a race motor...do it. But if you want more than a couple thousand miles out of it, then you need less piston speed...which means less stroke. No way around it.

Do a little Google'ing and research acceptable piston speeds and such, you'll see.

But here's a quick cut-and-paste for you:

Quote »"PISTON SPEED in FEET PER MINUTE

What is a safe engine speed ? How much rpm is too much? When does it become damaging to the engine? Generally speaking anything under 3000 feet per minute piston speed (or more correctly piston travel) will not harm an engine. In a high performance application 3500 FPM can be used since the burst at that speed will be short in duration. For racing most engines are outside of this envelope and are hurting themselves from the minute the RPM climbs above safe piston speed. Good parts changed regularily is the only solution to that problem. This piece is about how to plan to keep the engine below where it is hurting itself. IE If a 440 with a 3.75" stroke is turning 4000RPM the piston speed is-- Stroke X 2 X 4000 divided by 12 = FPM or 3.75" X 2 X 4000/12 = 2500 feet per minute which is very safe however if it turned 8000 RPM that would be--- 3.75 X 2 X 8000/12 = 5000 feet per minute which would require "the broom" if anything but mega buck parts were used. This can give you a pretty good idea of what a reasonably safe engine speed is and what it is not...[/quote] - Brian

[USsil80]

very nice write up how ever did it... where did you find that... nissan did the same thing with the sentra ser motor.. that thing has a huge stroke.... which i think hurts it powerpotetal

[PandaS14]

Another thing to note that keeps ka's from being able to withstand high rpm beatings is the unbalanced crank. It's not a fully counterweighted crank, which means the higher the rpms, the worse the vibrations (harmonics) get. So even with a destroked ka, with the stock crank, you are still gonna shake your engine to death at sustained high rmps.

Here's a pic of a fully counterweighed crank versus a half counterweighted crank (like ours) from Devious' site.



So the bottom line is, unless you have a ton of cash or a full machine shop, you aren't gonna get the ka to sustain 7500+ rpms. Why must everyone be obsessed with making ka's rev to infiniti, instead of concentrating on a more attainable goal such as making power within the ka's rpm range? Do that first, then if you still aren't satisfied, try upping the redline.

[Kouks]

So if I understand correctly 96mm is 3.80"? I looked at a ruler....

3.80x2x7000rpm/12=4433ft./min.

With a 102mm stroke(that of the stroker kit) 2.6L

4.07x2x7000/12=4748ft./min

[:: orion ::]

Making the KA have MORE stroke is NOT the way to make it more "sporty"...

That stroker kit would be nice for a 4X4 application, but not a 240SX.

Stroking it to gain ~400cc would yield less power then destroking to 2.2L it to gain ~1000rpm.

...

And your math looks correct...

FYI, 1" = 25.4mm

So 96/25.4 = 3.78 (3.8 is close enough!)

- Brian

[Kouks]

Okay, I gotcha. However, it sounds like it would gain alot more torque, but youre right on the sportiness....reluctance to rev is a beotch!