SR pros? cons?

[burnin240sx]

i'm planing on doing a SR with a smal goal of 300hp. with the other goals being 50/50 balance. What are the good and bad things about the SR that i should look out for well i'm trying to plan out my project?

[S13240]

It's not a special engine. It's just like any other engine out there, as long as you take care of it...it will take care of you.

Just mainly look out for modifications on the driverside due to steering stuff.

[burnin240sx]

i think i've choosen to go with a ka due to the iron block and the more displacement. unless i'm missing something here?

[extheflow]

i think i've choosen to go with a ka due to the iron block and the more displacement. unless i'm missing something here?

not really missing anything, at the 300hp level there's not really much of a monetary difference between the two.you'll need a turbokit for the KA wich costs as much as an SR ,and an upgraded turbo.so look for a little more wrench time on the KA at the benefit of a little more torque.unless you're paying for labor at wich point i would guess you'll pay more for a 300HP KA.

[VitaminT]

You will save a little front end weight with the SR...I think is about 40lbs.

Why go with an IRON block? It is heavy and the SR block (and internals) will very much hold the power level you are talking about.

[Dori Dori]

KA should be safe at those levels and you'll get faster spool...it's kinda pushing the internals though.

SR can do it with more ease for sure. You'll also have a higher redline and more peice of mind.

CA is another option. Lighter than an SR, iron block, and can make 300hp easily as well. It's also really cheap!

[burnin240sx]

the ka has more torque range and i'm planing on upgrading the pistons and possibly the rods too. maybe ross rods....i'm sure I will.

[Hijacker]

The main reason that the SR is a better choice as a turbo engine than the KA is in the bore/stroke ratio. The KA doesn't have a square ratio like the SR, so it's more likely to spin a rod bearing due to the unbalanced nature of the ratio. The torque curve of a KA-T is very nice, though. It's a trade off of smoothness for the small gain in torque when you go with a KA-T

[burnin240sx]

i'm sory i don't understand what u mean by square ratio? i do plan on changing the compression to 8.5 when i do the internals. cause it has hi compression and that's good for na but not turbo. is this what u mean? or are you taking about storke length?

[Hijacker]

the bore/stroke ratio. The SR has an 86/86mm bore/stroke ratio. The KA has a longer stroke, and a smaller bore, so the ratio isn't square. This is why the SR feels very smooth through its power band.

[Onizuka]

i'm sory i don't understand what u mean by square ratio? i do plan on changing the compression to 8.5 when i do the internals. cause it has hi compression and that's good for na but not turbo. is this what u mean? or are you taking about storke length?

High compression is GOOD for turbo, you'll get more horsepower and faster spool. Unfortunatly, high compression is more prone to detonation, but as long as you take the proper precautions it will still work (better).

NeedCAforS13 has a CA18DET that is using the CA18DE block and pistons for higher compression.

[IvoryJ30t]

a motor being undersquare has nothing to do with tendency to spin rod bearings.

[IvoryJ30t]

maybe you meant rod length/stroke ratio, and the lateral forces applied to the piston/cylinder walls.

a long stroke and a short rod has a tendency to oval cylinder bores and spin bearings at high loads/rpm.

[Dori Dori]

Do the math and you'll find that a KA has a better rod ratio than the SR. It's 1.72 while the SR's is 1.58. Consider that an ideal (from a performance standpoint) rod ratio is 1.75. Just adding some fuel to the fire...:icon18

[VitaminT]

Yeah I was about to say something about the rod:stroke ratio. When lowering the compression in the KA dosen't that mess with the quench area? Is it a major issue?

[Phax]

i think i've choosen to go with a ka due to the iron block...

If you build and tune your motor properly, an aluminum block is fan-freakin-tastic.

For street driving, if I were to do it all over again, I would have turboed my KA. Not because it has an iron block, but because it has more displacement. And for what I spent on purchasing the SR and getting it ready to handle big boost (~$3500), I could have had a turbo kit and fuel system, plus a turbo friendly KA bottom end.

I went with the SR, because I truly believe that when it comes to flowing a lot of air, and high boost levels, the SR is a better, more turbo friendly engine. If you're content to stop at ~300hp, you can do that all day with a KA.

[Nathan]

I went with the SR, because I truly believe that when it comes to flowing a lot of air, and high boost levels, the SR is a better, more turbo friendly engine. If you're content to stop at ~300hp, you can do that all day with a KA.

I dont know about this, I haven't seen an SR head, but the KA one is relatively free flowing, more so than a CA imo. With some headwork and cams I think a KA can easily keep up in that department. My big problem is the SR's aluminum block, seems like it'd be way to easy to strip the threads in various mounting holes and things. I cant stand aluminum because I have a tendency to bang it up

[Phax]

...My big problem is the SR's aluminum block, seems like it'd be way to easy to strip the threads in various mounting holes and things. I cant stand aluminum because I have a tendency to bang it up

Aluminum is a bit of a ***** like that. I stripped the threads on the drain plug to my Greddy oilpan. That thing is made out of aluminum.

[SRdave240]

If you are only looking to making 300whp, who cares if it is an aluminum block. Come'on That is one of my last worries as far as making good numbers. As far as stripping threads, just take your time and don't force a crossthreaded bolt. And if you do, there is always helicoil.

[burnin240sx]

this is my first project and i'm trying for realistic goals in my mind at first. then i'll work from there.so 300hp will be my first goal then at that time i should know more about what i want and if i want/need more hp or torque

[Phax]

If you are only looking to making 300whp, who cares if it is an aluminum block.

Aluminum doesn't matter. I've seen 1100+ hp turboed aluminum motors. Bashing on aluminum motors just seems to be a popular past time.

[Onizuka]

The fact that the block is aluminum really has nothing to do with how much HP the block can take. I have NEVER seen a SR needing a block guard, ive seen stock blocks take 750-800 horsepower easy. That is the worst argument on the planet.

Weight:-SR20DET is ~490 with all the turbo stuff on it-SOHC KA is ~490 with no turbo stuff on it, a KA24DE-T probably weighs 550-600lbs

Stock Internals:-SR guts have been brought to 550hp-KA guts have been brought to 300-310hp (could be higher, but is yet to be explored)-neither power figures apply to a regular person with a regular budget (tuning to reach those power levels is really expensive), but the SR stock internals are stronger. Most regular people only get 240-260 hp out of the stock internals on the KA, and 300-350hp on the stock internals in the SR.

Torque:KA has the advantage, but that doesnt mean the SR has a shortage of it

Price:If you argue which is cheaper you are a fool.

Aftermarket:SR has the advantage

HP per PSI:It really depends. A T88 at 7psi on the SR will make a **** load more horsepower than a 7 psi on base turbo kit for the KA. Even with the same turbos, it depends on other performance upgrades and the extent of tuning.

[Nathan]

The fact that the block is aluminum really has nothing to do with how much HP the block can take. I have NEVER seen a SR needing a block guard, ive seen stock blocks take 750-800 horsepower easy. That is the worst argument on the planet.

Weight:-SR20DET is ~490 with all the turbo stuff on it-SOHC KA is ~490 with no turbo stuff on it, a KA24DE-T probably weighs 550-600lbs

Stock Internals:-SR guts have been brought to 550hp-KA guts have been brought to 300-310hp (could be higher, but is yet to be explored)-neither power figures apply to a regular person with a regular budget (tuning to reach those power levels is really expensive), but the SR stock internals are stronger. Most regular people only get 240-260 hp out of the stock internals on the KA, and 300-350hp on the stock internals in the SR.

Torque:KA has the advantage, but that doesnt mean the SR has a shortage of it

Price:If you argue which is cheaper you are a fool.

Aftermarket:SR has the advantage

HP per PSI:It really depends. A T88 at 7psi on the SR will make a **** load more horsepower than a 7 psi on base turbo kit for the KA. Even with the same turbos, it depends on other performance upgrades and the extent of tuning.

I agree with you on all of this, but so far 350whp HAS been proven on a stock block KA...just only by like one person I know of The bottom line is they are both good motors, you cant really go wrong with either one imo, just for some one is better than the other, such as cross threaders like myself!