Cost comparision

[kysard]

I've been looking at the SR20DET vs KA24DET comparision, I think the answer depends on what you ultimately want to do. I put down some notes this is for building a 250rwhp car with the potential to upgrade without taking the head off again. Have I missed anything?

http://userweb.suscom.net/~kysard55/kavskedt.doc

[Syntax360]

hey, u forget to tell me where i can get one of these SA24DET engines that u speak of....? :-P aren't typos a *****?

[WDRacing]

At 400hp you should start thinking about resleaving your SR.

What exact fuel management are you going to use?

[kysard]

yea resleeve thats why I put iron block on the KA , adding resleeve on the SR.

For engine manageent I had a megaquirt but I sold it because it doesnt control ignition, they claim a future version would have it.I am very interested in going JY for all components and putting those savinga toward a stand alone. I like the fact that the MAF can be removed and when I grow tired of the ride the stand alone can go to my next ride. Not sure about the tuning with a stand alone turbo,, I dont want to spend a bunch of money on a dyno. I havent studied the ignition on the 240sx, but I imagine it is like the SR where you have to the ignition from an ECU?

[95_240sx]

What are you wanting to do with the car?

Rick

[kysard]

I'm looking for 230 to 250 hp with excellent driveabity and good milage, no plug fouling, no pinging, no detonation, no stumbling no hesitation, no bogging down

I dont have experience with FMU's or piggy backs but I imagine that I will need a standalone to get a well tuned 250hp car?

I've looked at the turbo kits available for the KA24DE and I cant help but think that if you could find a manifold and a downpipe you could go turbo real cheap on JY parts and spend what you save on good a good speed density engine management.

[syka24et]

I havent studied the ignition on the 240sx, but I imagine it is like the SR where you have to the ignition from an ECU?

The ignition on the sr is a lot stronger. Individual caps for each plug. I am almost certain an ignition upgrade will be necessary for the ka motor even at low boost.

[TrunkMonkey]

I am almost certain an ignition upgrade will be necessary for the ka motor even at low boost.

nope. most of the turbo KAs i've seen run the stock ignition system.

-demetrius

[hannibal]

You wont NEED a standalone to hit 250whp. Its definitely better than a ECU/piggyback setup, but much more expensive. If you got the money, go for it. But you can probably save a bit by going with a JWT ECU or just adding a piggyback.

[cnichols]

nope. most of the turbo KAs i've seen run the stock ignition system.

-demetrius

I feel that the stock system is fairly powerful...when I ran a 75 shot of nitrous, it never missed a beat...ever.

I've since upgraded to the HKS Twin Power for when I start turning up the boost on my KA-T.

[kysard]

I'm finding that lower compression pistons for the KA are expensive forged units which makes things more expensive: bottom end looks like over $1000 to rebuild. This puts thing about equal in cost. Too bad there arent good cast pistons for these KA's, I dont like fooling with forged pistons I have found a thick top high silicon cast piston much better for street use. Nothing like the stock ST20DET pistons available?

[erich]

nope. most of the turbo KAs i've seen run the stock ignition system.

-demetrius

The stock ignition on my KA-T had problems above 5psi with the stock gap. I put a Mallory Hyfire 6A (MSD 6A clone) and a MSD Blaster SS coil in and haven't had a problem since.

[WDRacing]

I'm finding that lower compression pistons for the KA are expensive forged units which makes things more expensive: bottom end looks like over $1000 to rebuild. This puts thing about equal in cost. Too bad there arent good cast pistons for these KA's, I dont like fooling with forged pistons I have found a thick top high silicon cast piston much better for street use. Nothing like the stock ST20DET pistons available?

I wouldn't worry about pistons until your going past the 350RWHP mark.

[Ian]

I wouldn't worry about pistons until your going past the 350RWHP mark.

lower than 350whp do i need to change the rods or any head units on the KAE?

[kysard]

I found that the 95 and up KA240DET has HT pistons which are good, however the ring lands can still be a problem.

Has anyone lowered compression by opening the combustion chamber or dremeling the piston ?

[TrunkMonkey]

I found that the 95 and up KA240DET has HT pistons which are good, however the ring lands can still be a problem.

all dohc's have the same pistons.

Has anyone lowered compression by opening the combustion chamber or dremeling the piston ?

you really need to know what you're doing when you start taking material away from the combustion chamber and/or the piston.

leave these methods to the experts.

-demetrius

[kysard]

No the S14 pistons are HyperTeutonic which is a better alloy, dimensionally they are the same but the metallergy is better on the S14 KA24DE.

[TrunkMonkey]

No the S14 pistons are HyperTeutonic which is a better alloy, dimensionally they are the same but the metallergy is better on the S14 KA24DE.

:rolleyes there is no such thing as a hyperteutonic piston.

ALL dohc pistons are the same. S13 AND S14.

please show us some proof that the pistons are different.

-demetrius

[lessthanjakejohn]

Hypereutectic is the word you are searching for.

Cast aluminum hypereutectic alloy has a high silicon content (sand) its benefits are low thermal expansion and low heat flow.

I searched all over and found nothing to bck your claim.

[C-Kwik]

No the S14 pistons are HyperTeutonic which is a better alloy, dimensionally they are the same but the metallergy is better on the S14 KA24DE.

This was actually a rumor that went around in the 240 community for a while. Someone determined that the part numbers for thepistons for the S14 and S13 were the same therefore the S14 received the same pistons. So, until someone proves differently, it stands that the S14 pistons and S13 pistons use regular cast aluminum pistons.

[kysard]

part #'s are the same because the new pistons are a direct replacement for the old ones. Nissan's casting process was upgraded, making the S13 DE pistons obsolete Nissan wouldnt keep two casting processes if the new one works in the old block. All tolerances etc were the same

[TrunkMonkey]

part #'s are the same because the new pistons are a direct replacement for the old ones. Nissan's casting process was upgraded, making the S13 DE pistons obsolete Nissan wouldnt keep two casting processes if the new one works in the old block. All tolerances etc were the same

even if this was true (which i seriously doubt) then that would still mean that all the dohc pistons are the same. there's no need to say that the S14s are better if they both use the same piston.

-demetrius

[WDRacing]

I sincerely hope Nissan didn't switch. I've never heard anything good about HyperCraptic pistons. Especially in a forced induction/high CR setup. Could one of you stateside guys give Nissan a call.

Someone asked earlier if you need to replace the rods for a hp goal of under 350. IMHO as long as you don't have any detonation you won't need to upgrade the block at all.

WD

[kysard]

even if this was true (which i seriously doubt) then that would still mean that all the dohc pistons are the same. there's no need to say that the S14s are better if they both use the same piston.

dimensionally the same but metallurgically different. I am surprised that you would call it Hypercraptonic,Corky Bell touts hypereutectic as the best metal for a street car. It is strong, not as strong as the forged pistons but more streetable (no slap, and no special tolerances) My experience with forged pistons on a daily driver have been poor, they just dont hold up for 100K miles.

Buick used the hypereutectic pistons on their stock 3.8L trubo and they perform well up to 500hp, they do have much better ring lands and a heavy top than the nissans. I think the stock SR20DET pistons are HT as well