NA Motor Discussions regarding N/A KA24E, KA24DE, and SR20DE

KA24DE design Q's

Old 10-28-2008, 09:19 AM
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KA24DE design Q's

I am currently working on saving up for my SR20DET swap for my project car, however my father and I had an idea for a motor to be built after the SR20 is in. This would give me a good motor to use in the car and get the vehicle running while the big motor build is in the works (Current KA24DE in the project car was FUBAR'd by the previous owner).

My questions are about the KA24DE. I wanted to know if the KA24DE is a sleeved block, and what the maximum bore and displacement that was achieveable through over-boring. I was planning on building my own big bore setup ie. selecting everything myself instead of paying extra for someone to track down a combination. I am currently a machinist in training and have access to a fair number of machine tools, so if the block is sleeved I could create my own sleeves for the motor in what ever size I needed and could fit. I was planning on a big bore and turbo setup if the motor is sleeved. Othrewise its not really worth my time becuase I dont have access to engine specific machine tools.

I did come across this line during my search but cant find a maximum displacement through over boring.

"If you are allowed to bore you can look into the maximum bore of the KA block which is 91.5mm and go with a set of VG33E pistons which are 91.5mm."

This is currently just a project idea but it gets me major points in machining class and would be nice to do. Any info would be appreciated.
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Old 10-28-2008, 09:37 AM
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if i had the money id buy a Brian Crower 2.6liter stroker kit

dude **** is insane do that build the head and you got yourself an insane motor **** puney sr20 lol
http://www.briancrower.com/makes/nissan/ka24de.shtml

also im not sure if its sleeved or not but i dont think it is
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Old 10-28-2008, 02:10 PM
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No KA's are not Sleeved

Max Bore would be 91mm For N/A and 90.5mm for turbo due to Thin walls and high pressure...
Atleast those are my precaustions for Max Bore, Very few 91mm Bore Pistons, mostly 90.5mm
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Old 10-28-2008, 05:24 PM
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would be awesome to see a custom built big bore KA though, i say do the KA!
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Old 10-28-2008, 05:32 PM
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^91mm are already THIN walls, any bigger and you'll have piston -> piston contact...
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Old 10-28-2008, 07:02 PM
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i have a buddy here in japan rocking a 2.7liter KA
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Old 10-28-2008, 07:04 PM
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Whats his dimensions? (Bore/Stroke)
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Old 10-28-2008, 08:09 PM
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Thats what I feared. Oh well...Ill just stick with the SR for the time being and look at the big bore for it later on. Still trying to talk my father into the RB but it may be just a tad too much work compared to the SR.
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Old 11-29-2008, 01:23 AM
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Originally Posted by Lord Umoja View Post
Thats what I feared. Oh well...Ill just stick with the SR for the time being and look at the big bore for it later on. Still trying to talk my father into the RB but it may be just a tad too much work compared to the SR.
Dude why would you want an sr the valve train sucks.
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Old 11-29-2008, 10:44 AM
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Originally Posted by BigVinnie View Post
Dude why would you want an sr the valve train sucks.
I'm going with the SR becuase for me its a fairly cheap replacement that nets me a factory turbo motor that should stand up to my requirements. I am building my car as a daily driver first, show car second, and possible drifter third IF I can find a set of local drift events. Call me a ricer if you wish, I have my race car already. Later on after I have the car running, and the exterior/interior finished, I will probably pull the SR, beef up the internals, rebuild the head, and add a larger turbo and related gear.

As for why I dont mess around with boring or turbo'ing a KA? I have had experience messing around with a stock NA 4cyl before and learned that its better to fix flaws in a motor than try to deal with new ones you introduce. My first car was a 2002 Focus. Factory the motor was rated at a rather optimistic (IMHO) 130hp with 9.6:1 compression ratio. I ended up looking for more power naturally aspirated and ended up with a 200hp camed up focus with 10.8:1 compression after shaving a Ford Racing head .040". The higher compression introduced a problem with the spark system, becuase as you compress a fuel/air mix more it becomes easier to self-ignite, but has higher electrical resistance and makes your spark weaker in relation. I ended up having the compression so high that the stock coils began to have issue pushing a spark through the mix to ingite it, so in went high power coils and better wires. The increased compression also lead to cold start issues and a world of problems I didn't really expect. I think for this project I'd rather try to improve a motor as I need it than to deal with new issues created by a bore/stroke change.

I understand you are trying to offer advice but at this point it seems that the SR is the better alternative for me.
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Old 11-29-2008, 06:36 PM
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Well heres my personal opinion dealing with Nissan/datsun 4 bangers for years, you can call me out on B.S since this is just opinion based.

Cast iron datsun/nissan blocks are heavy. They are also hard when it comes to reducing and disapating heat, unlike the aluminum block. So yes the SR wins this category.

KA wins in displacement and torque, so for having a heavier cast iron block there isn't much of a difference in "head to head" acceleration between the 2 if against each other in the same s-chassis, with almost the same rated HP.

Honing is most effective on cast iron. People feel that just because a rebuild is taking place, that .010 or .020 boring will need to take place. This is false. Cast iron is pretty strong, and only becomes more tempered as engine tempratures rise. Steel rings will go before the cast iron cylinder walls will.
Personally I hate sleeving, it takes more hours than honing a cast iron block, and ultimately sleeve steel isn't as strong as a cast iron wall.

As far as rebuilding the KA it is cheaper, and parts are cheaper for turbo charging (I'm picking up a spare block for rebuild and internals for under $500). Most people that go turbo KA make there builds cheaper than the sr and use cheaper more reliable turbos than the garret T25 and T28 series.
Most use the Holset HX35 turbos which have lots of room for boost and I have found them used in wrecking yards for under $250. JGS has do it yourself manifolds for ka's which is better for placement of manifold to where placement of the brake booster is used.

KA bucket hydraulic valve train design is awesome. As you can use higher lift and duration cams than the sr without modifying the valve train.

The myth of rev and redline.
People claim the KA to be less rev happy than the sr which is a completly false statement as my stock NA block makes more rev, redline, and peak power than most stock NA SR blocks to date. It's all a matter of the oil used, ignition timing and fuel (K, and cas value) that are set that will ultimately make power as long as the harmonics of the crank shaft will handle that power to rev.

I do like the fact that the sr uses a fullycounterweighted bullnose crank over the KA halfweighted non bullnose crank. Truth is though there is no replacement for displacement.

The KA loves fuel. I've already blown injector 2 and 4 on my engine (using 270cc injectors), so now it is ultimately time to upgrade to (370 cc sr injectors and adjustable FPR). I maxed out my injectors at 98% duty cycle, and the KA was still craving for more fuel. Leaving base timing stock at 20btdc (distributor) and changing K value with the N60 MAF I maxed out power at 162 WHP. If I adjusted and advanced base timing a few degrees there would of been room to make maybe 5~6 more wheel HP.

Ultimately I plan to buy the PDM cams, install the 370cc injectors and FPR and estimate relatively close to 190+ wheel HP on a stock 9.5:1 CR. I will be more than pleased with those results just because of the compression ratio and the testing being done on my blended 95 Octane.

In relation to your discussion on ignition timing why not just upgrade to iridium plugs, as iridium plugs make 5 times the spark compared to platinum, and 7 times the spark of copper under extreme engine operating conditions. Iridiums also use the shortest electrode tips available as well to reduce fouling of of ignition spark (detonation-early ignition).

Personally I'm not into super high compression engines. Fuel becomes less stable and then alternative fuels like ethanol (which has lower BTU's) would need to be used. To cool intake charge and reduce cylinder chamber temprature ( to prevent knock and ping).

Anyway enough of my blah, blah, blah, good luck to you and your project.




Originally Posted by Lord Umoja View Post
I'm going with the SR becuase for me its a fairly cheap replacement that nets me a factory turbo motor that should stand up to my requirements. I am building my car as a daily driver first, show car second, and possible drifter third IF I can find a set of local drift events. Call me a ricer if you wish, I have my race car already. Later on after I have the car running, and the exterior/interior finished, I will probably pull the SR, beef up the internals, rebuild the head, and add a larger turbo and related gear.

As for why I dont mess around with boring or turbo'ing a KA? I have had experience messing around with a stock NA 4cyl before and learned that its better to fix flaws in a motor than try to deal with new ones you introduce. My first car was a 2002 Focus. Factory the motor was rated at a rather optimistic (IMHO) 130hp with 9.6:1 compression ratio. I ended up looking for more power naturally aspirated and ended up with a 200hp camed up focus with 10.8:1 compression after shaving a Ford Racing head .040". The higher compression introduced a problem with the spark system, becuase as you compress a fuel/air mix more it becomes easier to self-ignite, but has higher electrical resistance and makes your spark weaker in relation. I ended up having the compression so high that the stock coils began to have issue pushing a spark through the mix to ingite it, so in went high power coils and better wires. The increased compression also lead to cold start issues and a world of problems I didn't really expect. I think for this project I'd rather try to improve a motor as I need it than to deal with new issues created by a bore/stroke change.

I understand you are trying to offer advice but at this point it seems that the SR is the better alternative for me.
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Old 12-02-2008, 08:45 AM
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Well thanks to too much free time and WAY too much time driving the stang to and from school, a KA-T seems to be pulling me in as a project. It seems that the cost of the SR vs. KA-T leans towards the KA even for my power goals of 250whp. I have a while to decide as I'm praying for enough Xmas cash (told everyone all I wanted was cash and clothes) to get this motor done. I am going to have a racing shop tear down the motor and figure out whats wrong with it, maybe a re-hone. After I know the damage I will be able to decide what path to take SR or KAT. The torque is what is pulling me to do the KA, I love not having to shift from 5th in the Mustang to pass people.

If I go the KA-T route I will interintercool it and am currently trying to find the right turbo. I may just custom fab about all of it to save cash and geek out the engine bay.
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Old 12-02-2008, 12:54 PM
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HX35 Holset turbo KA24det

It's called the budget boost project.
http://www.sportcompactcarweb.com/fe...d_do_nots.html

Don't believe everything you read in that sport compact magazine article.

It claims that using the stock injectors are good for 225 wheel HP, I've maxed my injectors out for naturally aspirated at 162 WHP.

Also the stock MAF is not effecient enough for a longer rev range and power band. You will want to get your basic N60 MAF to extend the rev range a bit more to get peeak power into the 6500RPM range.

Last edited by BigVinnie; 12-02-2008 at 01:04 PM.
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Old 12-02-2008, 01:24 PM
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Originally Posted by BigVinnie View Post
HX35 Holset turbo KA24det

It's called the budget boost project.
http://www.sportcompactcarweb.com/fe...d_do_nots.html

Don't believe everything you read in that sport compact magazine article.

It claims that using the stock injectors are good for 225 wheel HP, I've maxed my injectors out for naturally aspirated at 162 WHP.

Also the stock MAF is not effecient enough for a longer rev range and power band. You will want to get your basic N60 MAF to extend the rev range a bit more to get peeak power into the 6500RPM range.

Very interesting....I have a copy of SCC's S13 Silvia conversion article I was planing on using for the SR stuff. This is looking easier and easier as time goes on. One of the Proffesors here at school offered to teach me in my spare time how to rebuild the dead KA even though I'm not in an auto-related
major. I may take him up on it next semester and spend the afternoons on my free days rebuilding the KA instead of paying a shop. Sure it will take longer but its free save for parts cost.
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Old 12-19-2008, 10:56 AM
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Figured I'd just add to this thread instead of making a new one. If you havent been following my other thread I am going to go KA-T with a goal of 250wtq. I am getting ready to do the rebuild of my KA block after Xmas and wanted to know a few things about the motor.

1: Are the bearings "Select fit" ie no standard bearing set, but a series based on the size of the rod journal? Biggamehit sent me this link: http://www.amsperformance.com/store/...roducts_id=303
It seems to come with new bearings for the rods, but if it's a select fit bearing motor, how do they know what ones I need. The prof helping me with my motor said he had a student blow a honda using "standard" bearings in a select fit motor. I know its over kill for the power I want to make but, I know myself well enough to know that I will turn up the boost later on.

2. I've asked around and got no answer but can someone please identify what the hell goes on this D-shaped port on the intake manifold? The previous owner removed so much from this car that I have no clue what all is missing or what goes where......

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