what would be better?

[Atomos]

The engine in my '90 240sx coupe is about to die. So I am going to have to swap in another engine. I am looking at ether a ka24de (turbo) or an rb20det stroked to be a 2.4ltr. I am looking for 350-400 HP. which engine would be the cheapest and most reliable to get that much power out of?Thanks -Atomos

[SingleCamSam]

Get another KA. In the end, making that much power will cost you just about the same with any engine. The KA will be easier to put in and get parts for though. If you're gonna stroke the RB20 to 2.4, why not just get an RB25?

[Atomos]

Get another KA. In the end, making that much power will cost you just about the same with any engine. The KA will be easier to put in and get parts for though. If you're gonna stroke the RB20 to 2.4, why not just get an RB25?

i can't afford to do an rb25.. i can get a KA or an rb20 for way cheaper than an rb25. once i get the engine i can then save up money and build it up as time allows.

What is it going to take to get a ka24det to 350-400 rwhp?thanks -Atomos

[SingleCamSam]

I'd say the most important part is your fuel and spark systems. Some good solid internals couldn't hurt either.

First, are you sure you want 400hp? If it's street driven that's an awful lot. But if you must have it i'd go with:

Forged 8.0:1 PistonsBeefy connecting rodsARP StudsDefinitely have the crank micropolished and knife-edgedPossibly O-ring the block

For the fuel system

300zx TT Pump300zx Filter72lb injectorsPressure Regulator

For spark

MSD 6aGood wiresColder plugsBlaster Coil or something similar

I'd tie all that together with a stand-alone from SDS or Haltech.

You might also have to get some better cams to make 400 but i'm not sure. What's up there is just for making sure your engine doesn't puke on itself.:pface

[Atomos]

Thanks. That seems a whole lot easier than I expected..Also what turbo would you reccomend for that setup? Yes it will be street driven so I need fast spool. Thanks again -Atomos

[SingleCamSam]

Quote »Thanks. That seems a whole lot easier than I expected..[/quote]

Wait till you get started. It's never as easy as it looks.

That's just a start anyway. Like i said it's just to keep your engine from blowing. It'll take sweat, blood, tears, and some moola to get 400 horses.

As for turbo you've got a few choices. You could pay out the arse for some fancy ball bearing HKS etc. Or you could just get a T3/T4 hybrid. For 400hp i think that a T3/TO4E 57 trim should get you there. Try to find some compressor maps for the turbo you want and do some research. I can't stress that enough. Research,Research,Research!:)

Actually there was a pretty good article in the last SCC (yeah i know, it's a mag) about how to read compressor maps, it's a little dificult to explain without visual aids.

Good Luck!

Sam

[Atomos]

Yeah i know it will be a pain.. but I was expecting a lot more work than that.. yeah i have that SCC I will research that.Thanks once again -Atomos

[SingleCamSam]

It might help to lower your expectations a little bit as well. Maybe drop your goal to 300hp if the car is street driven. It'll cut down on cost, make tuning less of a pain, and you can run the donkey piss they call pump gas here in the US. Believe it or not you may even be faster on the street with 300 rather than 400 because you will more than likely have a more streetable power-band. And a 2700lb car with 300hp will at no time feel slow to you. It's up to you. 400hp would be absolutely sick, but you'll still be able to smoke just about anything you see on the street even with 300. Just some food for thought.

[MojoMan]

Hey Atomos, where do you live? If you are lookin to build a kat Iv'e got a 96 ka. The valves one of the cyl is bad. The compression is 175-175-65-175. It happened while driving it to cali. Thats when I swapped to the sr. The Tech at mossy nissan in socal said the motors fine its mostly in the head. It would be great for a rebuild. Just an Idea.

[gyfer]

I am looking at ether a ka24de (turbo) or an rb20det stroked to be a 2.4ltr. -Atomos

I doubt you can do that. That's 20% displacement increase.

Pushing DE to 350-400rwhp would need 11-14psi. Depend on your configuration & application. You are pushing the limit running 9psi on stock DE.

Single Cam: There is never too much HP. Too much g straight & long road out there :p

[SingleCamSam]

Quote »Single Cam: There is never too much HP. Too much g straight & long road out there :p[/quote]

Damn straight!:ylsuper

I just wish horsepower was cheaper. :pface

[C-Kwik]

Forged 8.0:1 PistonsBeefy connecting rodsARP StudsDefinitely have the crank micropolished and knife-edgedPossibly O-ring the block

I'd tie all that together with a stand-alone from SDS or Haltech.

Upgraded internals is not a bad idea, but stock internals have seen 350 at the wheels with decent tuning at 15 psi. That being said, 8:1 CR is lower than you'll actually need. I'd go with 9:1 or 8.5:1 depending on how safe you want it and/or how much off-boost response you want to give up. Knife-edging is a bit extreme for a street car. It can throw off the balance of the crank and have more issues. If your worried about windage, bullnosing is a more reliable solution for the street.

For engine management, a JWT re-tune will work well if you don't want the hassle of tuning a stand-alone or even a piggy back.

[Exar-Kun]

DON't band-aide it...please.

build it right, its complicated, proper FMIC, fuel management, internals, etc are not cheap.....for either engine.-chet

[SingleCamSam]

Quote »Upgraded internals is not a bad idea, but stock internals have seen 350 at the wheels with decent tuning at 15 psi. That being said, 8:1 CR is lower than you'll actually need. I'd go with 9:1 or 8.5:1 depending on how safe you want it and/or how much off-boost response you want to give up.[/quote]

Point well taken. I was operating under the assumption that he wanted 400hp on pump gas from this thing, so i thought 8:1 might be advisable. Just to give the engine some room for mistakes. It would suck off-boost though.

Quote »Knife-edging is a bit extreme for a street car. It can throw off the balance of the crank and have more issues. If your worried about windage, bullnosing is a more reliable solution for the street. [/quote]

Yup, got me there too.:pface

[C-Kwik]

Even for 400 HP, I'm not convinced that 15 psi or 350 is the most we can reliably see on a stock bottom end. Not saying it isn't either. But,I would say 8:1 is unnecessary. Modern engines with modern technology has allowed engines to see much higher boost with relatively high compression ratios. Most factory turbo cars nowadays use 8.5:1 CRs. Even when they build the bottom end, they tend to keep the same CR, and in some cases go higher. I tend to believe that factories build somewhat conservatively. Which is why fuel injectors are slightly larger than needed, and CRs are lower than necessary. The lowest I'd probably go with CR is 8.5:1. For 350-400 HP, I'd probably use a 9:1 CR if I was building on the safe side.

[sil80drifter]

i want 10000000 hp on stock gas with 12:1 compression... how many lifetimes will i have to save up for?

sil80

[C-Kwik]

i want 10000000 hp on stock gas with 12:1 compression... how many lifetimes will i have to save up for?

sil80

Well, if you can get a similar power to displacement ratio as a Honda, you would need a 83,333 L motor. If each cylinder had a bore and stroke that was abouot 3.5x3, then you would only need about 176 cylinders. Imagine having to upgrade injectors or replace spark plugs on that...

[SingleCamSam]

Damn he's good.

[sil80drifter]

I bow before the attempts to answer my absurd questions...

sil80

[Exar-Kun]

someone read the "auto math handbook" like me....

hahahahaha. Im still debating the CA V. KA thing...-chet

[hannibal]

Im convinced the KAT is the way to go. First, it's already in the car. Second, It was sold here for over 10 years (E and DE), meaning there are plenty of good used parts to be found. Last, parts are cheap compared to SR, CA, or RB parts.For a beginner, there's no better way to go.

[sil80drifter]

I'm proud to be a beginner.

sil80