KA24DE -T rebuild questions

[Xicor01]

Hey guys I am in the process of breaking down my engine for a rebuild. I am in the process of looking at everything that I need in order to meet my goals. Eventually I would like to reach 500 whp but I wouldn't mind stopping at 250 for a while. Basically I want to rebuild my bottom and top ends for 500+ whp and do everything else with tuning. I plan on planing, boring, honing and cleaning my block.

Right now I am rocking back and forth between boring it to 89.5 or 90mm the question there is, how would the dyno charts read, would the torque band level out or would it spike? I am also going to balance all of the rotating assembly and keeping the stock stroke so don't mention the BC stroke kit, I want to make a smooth high revving engine.

I know the Compression ration needs to be low for high boost turbo's or other forced induction applications. CP pistons i can only find for somewhere around 9:1 compression, for some reason I feel like that's high, I would really like to avoid issues because i bought the wrong compression pistons.

In regards to the crank, has anyone knife edged a crank? if so what was the seen difference? would it be better to buy the BC full weighted crank (with stock stroke, yes they make one) than keeping the stock crank? remember I want to lighten the rotating mass and allow for smooth upper limits.

In regards to the rods, i was going to go with eagle rods, but i think.. crower maybe, someone makes an "Ultralight" rod. How would that effect rev limit or torque dyno. Also i know that keeping it light will make it easier to balance the whole system but how much would going to an ultralight rod really change, i looked up the shipping weight and its the same (3lbs).

I am going cosmetec Head gasket, they have different thicknesses, just point of clarification, that is for individuals who have planed too much off the block/head right? or is there an actual benefit for a thicker metal headgasket?

moving on to the top end, I have read mixed reviews about stoptech, has anyone had any problem with their springs or valves?

I have read somewhere that it is actually more beneficial to have the shop doing your work assemble your bottom end as well, such that they can balance it as they assemble. I know that I can assemble it correctly I am just worried about tolerances and if the BC fully countered crank needs more room in the block. has anyone had the shop assemble it for them? If so how much extra did you end up spending and would you recommend it to someone else as well.

sorry for the wall of text, Thank you for any help you may be able to provide.

[AdamR]

Read more. These questions are basic and could be answered by reading/searching.

[Xicor01]

while i agree that some of the questions are basic i was looking for expected change in dyno chart readings in regards to small variable changes. i was not looking for someone opinion on what is best or what would work. i do not what to know what you think is the best option for me. i want to know what the math would say when the displacement is increased one or twice over in the bore, how fast a spool time for the crank when knife-edged, or even a way of calculating optimum compression ratio.

if things are so basic and all i need is to search and read then, please please teach me your ways because i've been searching for 6 months now with no luck. i dont like coming to others for help, i just figured there are such debates going on with such topics that i would put my questions out there. maybe i should turn to nicco where the members care more about data and less about "search more"

[Kingtal0n]

first mistake: KA engine. Do not use this for 500 horsepower unless you are rich.

The reason there is nothing jumping out at you that says "here is what you do with your KA for 500 horsepower" is because thousands of dollars have been spent on learning the weaknesses of the KA engine at that power level and nobody is willing to share that info for free.

If you want 500 horsepower your best bet is to simply buy an OEM 2JZ-GTE engine, slap on a precision turbocharger and a SAFC with some larger injectors. That is a reliable, daily drivable 500RWHP pump gas configuration with zero guesswork.

[Kingtal0n]

Originally Posted by Xicor01

i want to know what the math would say when the displacement is increased one or twice over in the bore, how fast a spool time for the crank when knife-edged, or even a way of calculating optimum compression ratio.

And because you are so specific, I will be also

For math involving rough horsepower estimates, use these rough equations:
CID = Cubic inch displacement;
(CID * RPM / 3456) = CFM
CFM * .069 = lb/min airflow

So, for an SR20DE engine,
(122 * 7000 / 3456) = 247CFM
247 * .069 = 17 lb/min (170 horsepower)

that equation simply says that an OEM sr20de engine with 100% volumetric efficiency should produce 170 horsepower at the flywheel on a BAD DAY. Since .069 takes into account the air temp rise of a turbocharger, this estimate is LOW. But since we are neglecting the fact that an OEM sr20de engine is not at 100% VE around 7,000rpm we are actually HIGH in our estimate. That is why this equation is very ROUGH.

So lets turn up the boost some, SR20DET engine @ 14.5PSI:
(122 * 7000 / 3456) = 247CFM * 2 (double the atmosphere) = 494CFM
494 * .069 = 34lb/min (340 horsepower at the flywheel)
Now subtract drivetrain loss, about 13%, (340 * .87) = 295 RW Horsepower.

Most SR20DET engines with sufficient compressor flow and cams will product approx 300 RWHP at 15psi at 7,000rpm so this is very accurate estimate.

Notice if we bump displacement slightly (due to overbore) there barely any increase to the overall flow capacity of the engine. If you want a larger displacement then you need a bigger engine, dont expect an overbore to give you back any spectacular results. Knife edge crankshaft will reduce drivetrain losses, and reduce rotating mass, which is a good thing for fuel economy and 4-cylinder engines in general but again nothing spectacular will happen to your power output. and OPTIMAL COMPRESSION RATIO is a misnomer since atmospheric conditions change from second to second, so there is no such thing for these engines. You need to modify the ignition timing and air/fuel ratio, for instance, as the temperature drops outside, or going uphill, or in a very high water vapor situation, to compensate. Therefore, you best case scenario tune is "worst case scenario", that is, very conservative. If you tune to the bleeding edge, and then go uphill on a hot day, you are past the bleeding edge and engine damage may result.

[Xicor01]

yeah i know, I had considered the 2jz engine and probably in a few years thats where i will end up going. yet right now i am in college and this is the first engine rebuild i have done where i have changed the internals significantly, and where i have been in charge of what parts to use. so ideally i would rebuild the ka to gain experience on something not so expensive.

And like i said in my original text, i'm completely fine with stopping at 250 for a while and maybe Permanently if i have a fun and responsive turbo w/ torque band. but i have no way to trust in the guy who sold me this motor so i want to rebuild the inside to make sure it isn't going to screw me in the long run. if i'm going to be in there, i might as well do it right the first time.

[Xicor01]

Originally Posted by Kingtal0n

And because you are so specific, I will be also

For math involving rough horsepower estimates, use these rough equations:
(CID * RPM / 3456) = CFM
CFM * .069 = lb/min airflow

So, for an SR20DE engine,
(122 * 7000 / 3456) = 247CFM
247 * .069 = 17 lb/min (170 horsepower)

that equation simply says that an OEM sr20de engine with 100% volumetric efficiency should produce 170 horsepower at the flywheel on a BAD DAY. Since .069 takes into account the air temp rise of a turbocharger, this estimate is LOW. But since we are neglecting the fact that an OEM sr20de engine is not at 100% VE around 7,000rpm we are actually HIGH in our estimate. That is why this equation is very ROUGH.

So lets turn up the boost some, SR20DET engine @ 14.5PSI:
(122 * 7000 / 3456) = 247CFM * 2 (double the atmosphere) = 494CFM
494 * .069 = 34lb/min (340 horsepower at the flywheel)
Now subtract drivetrain loss, about 13%, (340 * .87) = 295 RW Horsepower.

Most SR20DET engines with sufficient compressor flow will product approx 300 RWHP at 15psi so this is very accurate estimate.

Notice if we bump displacement slightly (due to overbore) there barely any increase to the overall flow capacity of the engine. If you want a larger displacement then you need a bigger engine, dont expect an overbore to give you back any spectacular results.

why are you talking about the SR20det? and thank you for being specific, these equations were exactly what i was looking for.

[Xicor01]

Also thank you Kingtal0n for the last paragraph, it was what i was thinking, most of these questions i have answers two that i have come to on my own but i was looking for more confirmation.

[Kingtal0n]

This is your ticket right here. A JDM 2JZ engine is about $2000 or less. Do the fuel system right, add a journal bearing precision turbocharger and a SAFC and you have this: 500RWHP daily driver. You can use the OEM automatic transmission or the 5-speed 1JZ trans or even the 6-speed Getrag, although those are quite pricey.

My favorite idea is the automatic trans with an upgraded converter and a mild shift kit. Dont over turbo it. This car is overturbo'd; The previous owner, Larry (teamorange inc), is all about numbers, not actual performance, so you will see 800rwhp 1000rwhp etc... all day in his cars but none of them will perform well without a 300 shot of nitrous and slicks. Dont over turbo it.

[Xicor01]

yeah i cant stress how much i would love to do a JDM 2jz turbo but i just dont think that i can put down that much money in one payment. so if anyone wants to let one go for a considerably lower price i guess if i sold the used KA i have in the garage, the KA out of my car, and all the extra parts like the z32 conversion, z32 tranny, mishimoto radiator/ fans i might be able to muscle up 2500+, but that would only buy me an engine and not a drive-shaft, mounting, or any of the other things that i cant think of like compatibility of diffs, fuel pumps, stock subframs, steering Columns. :/ i think it could be possible... what would you guys do in my situation?

[Kingtal0n]

oem redtop sr20det. 200 horsepower 7psi of boost pump gas daily driver. Get a random Limited slip differential and have some fun on the OEM wheels.

[jacobs13]

[QUOTE=Xicor01;4975535]yeah i cant stress how much i would love to do a JDM 2jz turbo but i just dont think that i can put down that much money in one payment.

You dont think building your ka is going to cost more than that?

[Xicor01]

yeah but it will be 300 here and there, not 2000+ upfront.

[R33E8]

ka-t.org.. A 500hp ka-t isn't that hard, plenty of people are pushing that and more especially on E85 if it's available to you.. All you need is a big turbo, headstuds, ecu, fuel, pistons, rods, and kelford 272 cams.. You can leave the springs stock unless you really want to rev high.. High as in up to 7300, because above that you'll need a new crank.. 9.0 is fine.. If you run E85, go with higher compression pistons like 10:1.. You'll make more power with less boost..

If you have a choice, E85 is definitely the route to use.. You could probably make 500 on a completely stock cylinder head..