Ive searched alof of places on the net and got bits of info here and there but nothin that is complete. I opened this thread hoping people would talk about the general technical concepts of N/A(Naturally Aspirated) KAs. I'd like to kick start this with a few general questions.
People say that Stock KA cannot handle too much power. Why is this? What is the weak part that can't hold the power?
What is the idea behind swaping SOHC pistons into te DOCH engine to raise the compression? What kind of Ratio would we expect if this was done? What other than pistons needs to be dont to do this?
N/A KA- Q&A, FAQs, General Info.
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crash n burn
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Re: N/A KA- Q&A, f***, General Info. (killa_snake)
sohc pistons have a higher compression than dohc. 89' sohc made before feb.i believe had a 9.1:1 cr, and the dohc had an 9.0:1cr? i may be wrong, but i think the sohc had a longer stroke..so in essence..in a dohc, it'll be a high cr?
and the bottom end is weak on ka's..i, as a personal preference, wouldn't step foot over 300hp (some have gone 100+ over that with a completely stock motor, so who knows) without touching the bottom end, it requires forged internals to handle it
and the bottom end is weak on ka's..i, as a personal preference, wouldn't step foot over 300hp (some have gone 100+ over that with a completely stock motor, so who knows) without touching the bottom end, it requires forged internals to handle it
Other more knowledgeable people should chime in soon, but here's some info I've picked up. Please correct me if anything is wrong, I haven't studied lately...yes SOHC pistons will increase compression ratio in DOHC engines, but the earlier pistons need to be flycut so as to not damage the valves. (I don't know all the details on this so don't ask me)Personally, I think 300hp (turbo/NO2/whatever) is quite a bit out of a 4banger with stock internals. The KA already has forged rods and crank. If you're shooting for over 300hp, you probably should be looking at internals for most 4cyl engines anyway IMO.The main weak point of the KA series (besides not enough power) is that it generally doesn't like to rev too high. One of the major culprits seems to be the long runners on the intake manifold. The Rod/Stroke ratio also doesn't help in the rev department (can't remember if its undersquare or oversquare). There are probably other things too, but these designs also give the KA more torque than most 4cyl engines of its time, so obviously there are advantages and disadvantages.
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BOOMSHAKALAKA
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Re: (Ajax)
Someone spelled FAQs wrong...
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killa_snake
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Re: (topless94)
AHAHAHAHAH Faqs can an admin change that? :P
Re: (killa_snake)
You could get over 300 with a modest turbo setup. As far as the engine being weak, that isn't nec. true. It really is a pretty hardy engine. If your going to go to the extreme of all motor just swap you engine for a n/a sr, you can get them dirt cheap all day long, and no one wants them b/c of no turbo. Just about every Japanese tuner makes parts for the n/a sr.
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killa_snake
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Re: (halnfl)
Totally
of topic man, I dont wanan be a d!ck but Im tryin to not make this thread have anything to do with other engines... stricly KA.halnfl wrote:You could get over 300 with a modest turbo setup. As far as the engine being weak, that isn't nec. true. It really is a pretty hardy engine. If your going to go to the extreme of all motor just swap you engine for a n/a sr, you can get them dirt cheap all day long, and no one wants them b/c of no turbo. Just about every Japanese tuner makes parts for the n/a sr.
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Bigvinnie
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Re: N/A KA- Q&A, f***, General Info. (killa_snake)
Abel racing has built a KA24det with over 400 at the crank with stock internals using a DSM ECU from a mitsubishi eclipse turbo.The power is achievable, but the boost needs to be controlled. DSM does a good job of controlling power using KARMAN frequency along with a wide band 02.
The KA24de uses a pentroof design unlike the KA24E which uses a hemispherical head design. Hemispherical head design is normally hgiher fromTDC of the piston which means that the piston dish is raised in order to provide a much better compression. Too much open volume causes the cylinder volume to raise dropping CR. Pentroof design is normally made smaller and is much more compact in design raising the CR of the engine thats why piston dish is normally lowered when compared to the E pistons. So when you use E pistons on DE it will significantly raise compression ratio
The KA24de uses a pentroof design unlike the KA24E which uses a hemispherical head design. Hemispherical head design is normally hgiher fromTDC of the piston which means that the piston dish is raised in order to provide a much better compression. Too much open volume causes the cylinder volume to raise dropping CR. Pentroof design is normally made smaller and is much more compact in design raising the CR of the engine thats why piston dish is normally lowered when compared to the E pistons. So when you use E pistons on DE it will significantly raise compression ratio