NA ka24de guru's.. need help . WARNING: looooong read !!!

[HughJazz]

Running a NA ka24de in my SCCA road race 91 coupe and have some questions. Just did some pretty serious damage to my brand new engine and need to figure out why it happened and how to prevent it from happening again. Anyways, started running like crap and was obviously missing on a cylinder so I did a compression check. Here's what I got: #1 = 205 psi#2 = 18 psi#3 = 205 psi#4 = 205 psiPlease keep in mind that the engine is in a track only car and it's turned from 4000 rpm to rev-limiter 90% of the time it's running and it had prolly less the 3000 miles on it when this happened. This is a purpose built race engine so every machining and engine building trick you can think of....it got !!

Here are the engine specs:93 kade enginebored .020 and installed flat tops to bump compressionhead was milled and have a mild P&P job. 5 angle valve job, etc..BC stage 2 camseverything else is bone stock 91 NissanBasicly it's a professionally rebuilt kade ( balanced, blue printed, etc ) with flat tops, mild P&P'd head and BC stage 2 camsAll EGR has been removed and the only thing with vaccume run to it is the brake booster and FPR ( everything else is plugged up )I also run strait 112 octane Cam 2 race gas

Anyways I tore it apart and there were signs of serious detonation and the #2 piston was trash.

I'm guessing that with the extra compression, cams and turning the crap out of it the stock fuel system simply couldn't supply enough fuel.So far I've replaced the pistons / rings & bearings, added a new fuel filter and changed the stock fuel pump to a Walbro 255lph. I don't think that'll be enough to solve the problem though. Please keep in mind that this is the first import I've ever owned and my only other experience with fuel injection was with a 5.0 Mustang I drag raced back in the day

My questions are: 1: Should I replace the injectors ? What are the stock injectors rated at ? what " cc " injectors would you suggest I run if needed ?(please note : must be able to use in factory stock fuel rail )

2: If I change injectors will the stock MAS work properly ? On my Mustang when I changed injectors to larger ones I had to get the MAS recalibrated to work with the bigger injectors or it would flood like crap.

3:If I change injectors and need to recalibrate the MAS .... who or where can I send it to get it done ?

4: Should I install an adjustable FPR ? If so, what should I run the fuel pressure at ?

5: What about the ECU ? I was told that the ECU needs to be "reprogrammed ?? " to compensate for the extra compression, cams, etc . Who or where does that ?

6: What plugs should I run ? It had Autlolite 3924's in it when I got it so I've been using those

Anything else I need to look into ? I would love to put it on a dyno and dial in the timing/fuel but any of the shops remotely close by won't talk to you unless you have a Camaro or MustangPlease no comments about it needs a flux capacitor, fart pipe, NOS stickers, etc.... I need only replies from knowledgable people that know what the he77 they are talking about

[Razi]

If you put in bigger injectors, you need to get your ECU retuned to compensate for them.
Modified by Razi at 11:24 PM 5/2/2009

[chr1su12]

Hang on,

You have cams, high compression, assuming different intake manifold but what ECU tune are you running?

Piston #2 sounds like it borked the ringland, these arn't standard KA-E pistons are they?

MAS has nothing to do with your injectors, MAS sensors air flow/mass. It tells the ecu how much air you have and works out how much fuel you need, if you have bigger injextors, of course it will pump too much fuel and run like s***/rich. You need to get your ECU retuned with new injectors.

ECU tuning shops, there should be plenty in america!

Fuel pressure regulator, speak with your tuner as he will be adjusting that.

Use NGK Iridiums or something, get a heat range colder due to the higher compression.

By the way, what do you rev this to? Any info on power?

[liquid_cool]

If your running lean @ higher RPM's thats due to your fuel regulator and pressure not being tuned corectly under load..this would couse detonation...at idle you can easy be 40psi on your fuel pressure gauge, but under a load the pressure would drop drasticly..specially with larger injectors...there are regulators that have a vacume line type nipple so that under load..it adds more fuel pressure...malory makes one...as far as running rich with bigger injectors..i myself would rather run rich than lean...rich=safe...lean=problem...thats my 2 cents..hope this helps.

[rioredstang]

I am building a ka24de and was wondering how you have came out? I am using the 275/275 stage 3 cams. I have already had some tuning on my ecu. I still have stock injectors. send me a phone # in a pm so we can talk. I have a 1993 ITS car.

[liquid_cool]

my project went south due to unexpected rod stretch and a few smacks of the pistons on the head..lol..if ya wana talk shop..im cool with that here on the forums bro..its free here and money is tight..allso i will respond to ANY question asked of me on my myspace....

as for this problem here..there is a few solutions..better regulator for fuel/air..a good fuel/air gauge with warning light...better pump..and a piggyback might help tune it better.