high compression ka24DE

[blackS13]

I want to run high compression on my KA24de. I dont want to have to run a fuel system of any kind...injectors at most. I want to run 10:1 compression and not detonate. has anyone run 10:1 compression on KA24de's and not detonated? I am just curious about what to do and expect from a 10:1 compression KA, also i am still looking for pistons for that KA that are 10:1, thanks all, please please aim IM me : sn: Turbotractionemail: [email protected]

[AmoebAssassin]

If you put KA24E pistons into a KA24DE block, you get a 11.something:1 CR. I'm not too sure of the specifics, but do a search, the info is on here.

[blackS13]

yea i dont want to use stock pistons, also I want no high than 10:1 compression. I cant find any pistons that are like that yet...just wana know if anyone knows of them

[Veriest1]

You'll probably just have to call Wiesco or another reuptable piston manufacturer and custom order them.

[cdlong]

yea i dont want to use stock pistons, also I want no high than 10:1 compression. I cant find any pistons that are like that yet...just wana know if anyone knows of them

why not, you will get more power with 11.1:1 and you can still run pump gas (premium, but still from the pump). and stock pistons are perfectly good for the ammount of power you will get from that setup. i wouldn't use used pistons, but you can get stock replacement KA24e pistons pretty easily.

there are plenty of people that have done it without issue. research it some more before you go blowing money on custom stuff that isn't any better.

[blackS13]

Yes but stock pistons wont be forged and hold nitrouse....also....at 11:1 it will detonate with the 91 octane gas we have here for premium

[Bigvinnie]

at 11:1 it will detonate with the 91 octane gas we have here for premium

The car won't utilize any type of performance, but can infact use really high compression pistons on that fuel. KA24de's use a knock sensor, and with an ecu tune you could use the 10.5:1 pistons and higher 11.1:1 and probably utilize it alright on 91 octane. The only reason why this would be possible is that timing becomes retarded to impending knock. The higher the knock rating the more retarded timing becomes.It is used alot in todays engines (like BMW) which runs between 11~12.1 CR on most of there performance engines and can run on 91 octane. Same goes for the 350z which runs a compression 11.1, and utilizes 91 octane.The greatest importance of using a 10.1:1 CR is to pass the standard NOX emission testing, which will almost become impossible, if the CR is increased any higher. Unlike BMW or the new VQ35 platform, the KA uses extremely large piston surface area, and consumes alot of air in it's bore and stroke. This means that there will need to be much more fuel dumped to compensate for more air, inorder to lower the NOX (or cylinder tempratures).For a Californian 10.1:1 is the safest bet to take to pass the smog test, but if you aren't to concerned with your smog laws then screw it, 10.5:1 would work just fine on a NOS setup, with 91 octane.
Modified by Bigvinnie at 4:17 PM 1/25/2006

[blackS13]

Yes but stock pistons wont be forged and hold nitrouse....also....at 11:1 it will detonate with the 91 octane gas we have here for premium

[SimpleEnigma]

Did you read any of the above posts about why the KA24E pistons will be just fine?

You will not detonate with the 11.1:1 CR produced by the E pistons because of the knock sensor built into the DE motor, as long as your timing is set to factory spec. There are a whole slew of guys on here running the DE head with E pistons on 91 octane with no problem.

Secondly, Those pistons can handle a great deal more power than you will be producing in N/A spec, even with nitrous. Somewhere in the range of 350whp is where the pistons being cast instead of forged becomes an issue.

Thirdly, I do agree with you in part with the nitrous. I would not use the E pistons if you plan on using nitrous, the CR produced by those pistons is a little too high for a nitrous application using only 91 octane fuel.

The stock compression ratio of the DE motor is already 9.5:1, and I believe that if you only want to bump your compression up a 1/2 point you will have to custom order a set of pistons.

Lastly, the stock fuel system will be able to handle the 10:1 CR just fine.

[InsanityInc]

People who think that nitrous and high compression work well together are retards. High compression and lots of nitrous is a surefire way to make your engine live a VERY short life.

Nitrous MAY cool your intake charge. However, the temperature of your intake charge is actually INVERSELY related to your cylinder temperature during ignition.

The colder the air coming in, the denser it is. The denser the charge, the more fuel that gets injected. The more fuel you burn, the more heat you get. Therefore, the colder your intake charge, the HOTTER your cylinder temperatures.

Higher compression ALSO raises your cylinder temperatures.

Any large amount of Nitrous with that high of compression will either cause knocking or just incinerate your rings/exhaust valves.

[cdlong]

The stock compression ratio of the DE motor is already 9.5:1, and I believe that if you only want to bump your compression up a 1/2 point you will have to custom order a set of pistons.

S13s are 8.6:1

[InsanityInc]

S13s are 8.6:1

No... KA24DEs are all 9.5:1. Early KA24Es were 9.0:1 and later KA24Es were 8.6:1.

[cdlong]

where did you get your info? this is where i got mine.

http://www.socal240sx.com/faq/1989.html ... /1993.html

and just for referencehttp://www.socal240sx.com/faq/1995.html

[Ajax]

where did you get your info? this is where i got mine.

http://www.socal240sx.com/faq/1989.html ... /1993.html

and just for referencehttp://www.socal240sx.com/faq/1995.html

Weird.MSN Autos lists it as 9.2:1:

Engine Specifications 2.4L 155 hp I4 Horsepower 155 @ 5600 RPM Torque (lb-ft) 156 @ 4400 RPM Valves/Valve Configuration 16/DOHC Displacement (cc) 2393 Bore X Stroke (in.) 3.50 X 3.78 Compression Ratio 9.2:1 Fuel Type/System Gas/SEFI Turbocharger No Supercharger No

[Bigvinnie]

People who think that nitrous and high compression work well together are retards. High compression and lots of nitrous is a surefire way to make your engine live a VERY short life.

Nitrous MAY cool your intake charge. However, the temperature of your intake charge is actually INVERSELY related to your cylinder temperature during ignition.

The colder the air coming in, the denser it is. The denser the charge, the more fuel that gets injected. The more fuel you burn, the more heat you get. Therefore, the colder your intake charge, the HOTTER your cylinder temperatures.

Higher compression ALSO raises your cylinder temperatures.

Any large amount of Nitrous with that high of compression will either cause knocking or just incinerate your rings/exhaust valves.

Not to disagree. But rather add to your statement. Yes running rediculous amounts of NOS is retarded, but it doesn't mean that you can't run NOS on high compression, or turbo charge for that matter.Honda tuners have been doing it for years on high compressions between 10~11.1CR, at 5~7PSI on turbo set up's with no problems, and made more power than an engine would at the same PSI with a lower compression (power output added to forced induction is greater on higher compression than lower compression).Granted 8.1~9.8CR engines usually are high boosters and work well to keep cylinder tempratures down, when boosting anything phenomenal above 12PSI. But when it comes to power output it isn't as phenomenal as a high compression engine that makes those numbers on a fraction of the injection given.I mean if you look at the numbers to power output given a 9.1CR engine would need double the NOS fed injection, than what it would need for a high compression to make (at lets say 10.5:1CR.Steve Novaks car is a perfect example of a high compression KA that utilizes NOS fed injection and his car runs 11's in the quarter mile.There are methods used in cooling cylinder tempratures on high compression such as methyl/water induced injection, or anything as simple as backing off the timing to prevent detonation.Progressive NOS systems today are nothing to what they were 10 years ago either. Now there are systems that are so intuned and developed to work with the knock sensor that the system can shut down or lower injection if the knock responce is to high. Of course we are talking about $10,000 NOS fed injection systems, but they do exist.As far as rings becoming fried on NOS, that all depends on how stupid the driver of the vehicle is. Super tech pistons in the 10.5:1CR were developed with the thickest ring lands on the market to take the abuse of turbo and NOS fed injection... If it wasn't possible they simply wouldn't make it....Just my silly opinion, not here to argue.....
Modified by Bigvinnie at 10:22 PM 1/27/2006

[cdlong]

MSN is a horrible source. for example, it says an E30 M3 was supercharged, which it's not. it's a simple mistake, but i would take the word of a nissan specific site with scans of brochures over theirs anyday.

[pregmantis]

how much nos are you thinkin of using? People have been running over 100hp shot with stock pistons for a loong time.

[InsanityInc]

Independent calculations (cylinder head volume+piston dish compared to BDC volume) place the CR on a KA24DE to about 9.5:1. Those brochures are riddled with mistakes anyway, I've seen them before. Kind of sad when you think about it, considering they are genuine nissan.

Also, yeah you can run high CR and a little boost or nitrous, but definitely not much. Also, obviously the availability of race fuel changes things quite a lot.

EDIT:CR:

http://www.google.com/search?h...earch

[InsanityInc]

Also, page EM-43 in the FSM has the compression ratio listed as 9.5:1.

[cdlong]

i stand corrected

[Chezedik]

A guy here in town was using the E pistons with a 50 shot, never had ping issues, was pulling low 14 sec times.

[Ajax]

MSN is a horrible source. for example, it says an E30 M3 was supercharged, which it's not. it's a simple mistake, but i would take the word of a nissan specific site with scans of brochures over theirs anyday.

I didn't intend it as a source. I just thought it was weird that there are multiple sources with different numbers. I didn't express it very well, though, I admit.

[mr2lickit]

Yeah my friend did high compression on a KA, but it was machined and bored first. It was 10 or 11-1 compression. He ran nitrous too, but didnt get the chance to use it b.c he didnt maintain the engine (low oil). Pretty stupid way for an engine to go. Oh well..... The engine was also on pump gas 93 octane.

[Chezedik]

91 here.