SR20DET Top end with a KA24E bottom end

[mranlet]

WIth turbo technology the way it is at the present, there's little reason to stay NA unless you're a purist.

If I'm understanding all this talk about the Y-shaped follower, is the SR head really a "Overhead" cam head or is it rather a side-mounted setup? Does anyoine have any diagrams to illustrate this?

KA's larger diaplacement will warrant a stronger dig-out ability for when the revs drop in mid-slide and you don't have time to shift. At least as far as I'm concerned, a versatile broad and torquey powerband is infinately better than one that delivers twice the power at a bazillion rpm...

-MR

[AtroXR7]

I dont know why people are talking about the KA having a long stroke. the KA is a perfectly square engine, meaning the bore and stroke are the same. This is a great recipe for making a lot of power in an engine. If you want high revs, you want a bigger bore than stroke, and for great low end torque, a longer stroke. Look at a ford 5.4 truck engine, its similar to a 4.6 which is nearly squared, but has the same bore and a much longer stroke. Thre result, well, ask any with a race trailer. Its cheaper to put a chevy engine in a car to go fast, but you want a ford to pull the trailer no question. Now look at the new ford GT. it uses a 5.4 long stroke block, but increases the bore size a little to make the engine more square, some special heads and a supercharger. The result was a car the kicks the crap out of the high rev lamborginis and ferrarris. Square is a good thing, its balance, racing is all about balance.

Now back to nissan, I used to not like the KA as much as the SR because one... 2.0 has long been a magic number for powerful cars. And the work involved to make an NA car take the same amount of power as a boosted car is substaintial since you have to replace pretty much everything in the bottom end, short of the crankshaft. But with time Ive become more and more fond of the KA due to its square build and the good flowing heads. Plus half a liter can go a long way. Bore out the cylinders a bit and some better cams can really make the engine a competitor. Drop some big money on forged internals and you could swing a hybrid t03/t04 turbocharger and theres no longer a point in swapping an SR. Find some good parts sources and dont get raped buying internals *did you know most places are charging the same price for your 4 rods/pistons as I can get for my 8, and there isnt nearly as many companies competing for the business.* and you could be pulling a lot of power and holding it for the same price you would pay for a red top SR with tranny and harnesses.

['97 S14 SE Turb]

KA is not square. SR is.

KA's bore is 89mm. Stroke is 96mm.

SR's bore is 86mm. Stroke is 86mm.

[mranlet]

A well done swap can cost you $5-7k. A good turbo kit will cost you $4k. You do the math.

-MR

[hachiroku-fc3s]

Originally posted by '97 S14 SE Turb
Actually, the bore center is the same... There have been talks of using the KA crank in the SR...

Hmmm...I haven't heard these talks but I can say i've pulled both heads. Didn't measure the SR, but the bore spacing on the KA is unequal and the SR looked equal. I looked up the numbers. Bore spacing on the KA is supposed to be 96,98,96 and SR is 107,107,107.

['97 S14 SE Turb]

The talk comes from the SE-R mailing list. IIRC, Mike Kojima.

Those guys have been going at SRs since '91... They would know what they are talking about.

[nissanguy_24]

What are they going to wind up with a Sr23 or something? be a very torquy sr... and if you think the KA is unsquare.. this engine deffenately will be. Are they just looking for a cheap stroker kit? or something along those lines?

[hachiroku-fc3s]

Not saying it couldnt be done, but the machining skills required would make it simpler just to machine another crank anyway. And you are increasing the sideload on an aluminum block. Im sure it could be pulled off successfully and reliably but would need to be for promo purposes as it really isn't all that great an idea (little-to-no market, dangerous, too labor-intensive), especially with 2.2L stroker kits already available

[nissanguy_24]

Originally posted by hachiroku-fc3s
Not saying it couldnt be done, but the machining skills required would make it simpler just to machine another crank anyway. And you are increasing the sideload on an aluminum block. Im sure it could be pulled off successfully and reliably but would need to be for promo purposes as it really isn't all that great an idea (little-to-no market, dangerous, too labor-intensive), especially with 2.2L stroker kits already available

Yes but they are expensive, and deisgned primarly for FWD applicatons. These are FWD srs and probably FWD Kas they are talking about. They may be different.. i honestly dont know, but i guess thats why there sentra guys.. because they do know.

['97 S14 SE Turb]

JWT now has a 2.4L SR stroker kit.

[AtroXR7]

i was wrong... i had read somewhere that the KA was a completely square engine. But still it has a very high bore to rod length ratio which is almost as important. An overbore and new pistons isnt gonna cost that much to help things out, plus you can creep into the neighborhood of a 2.6 displacement. *JE custom pistons arent that much more expensive than predesigned*

Ill have too look at some dyno comparisons before i give any credit to either side tho. all these numbers are always talking about peak power... ask any one that actually races cars, its not about peak, its about how wide and how flat your power curve is in the powerband. Thats where everything is going on. I'd rather mod a car to give me 5hp through the entired band than mod it to give me 15hp near the peak but lil to negative gain on the lower rpm.

Im interested in this QR25DE engine tho. simplicity in design, more displacement, and its lighter than even the SR. Not to mention a LOT of talk about the 4wd transmissions that will bolt to it. Its gonna be interesting to see what happens with that engine.

[Ghost of Duluth]

SMC get on aim.

[BENJO]

im too lazy to read this whole thread (usualy im not) but yeah ive seen a sr bottom with a ka head in person. so its possible and takes the best from both worlds.