I am doing the secret cam swap in my '99 Z24, and I want to know what I will have to do to the engine to make it capable of revving up to 7000 since the secret cams make power up to that point. I know I will need stiffer valve springs, a high flow oil pump, and I am getting the balance shafts neutralized from JBP (JBP Link). What else would I need to change? Thanks.



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

I may be wrong but your oil pump and all that I don't think has anything to do with how High your motor revs...

Just off the top of my head, id get stiffer valve springs, ss valves and bronze guides, an angle valve job(3 or 5), p&p head. There may be other things you need done, but thats all I know.











~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ

I'm not sure about the LD9, but I'm working on my 4G63 DSM and to get it to rev higher I'm doing all the valve train, balance shafts are "removed" (they're there, the lobes are just taken off), and I'm balancing the rotating assembly too. I would probably recommend strengthening the rotating assembly just to be on the safe side because if you break a wrist pin or spin a bearing or something like that at 7K RPM, your engine gonna be really unhappy with you.


Opfer benotigt. Keine Erfahrung notwendig.

Victims needed. No experience necessary.

Oil pump is definately needed. The pump on the 2.4L is junk. Once redline hits, it doesn't put out enough oil to lubricate everything efficiently. So anywhere after 6200, there will be an insufficient flow of oil to the parts of the engine that need it.

Any one else have any expertise in this area?



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

definetly change the oil pump...as far as raising the rev limiter..the only way i know of is to use a 95 pcm with chip...anyone else ?

Cool, now I know lol.. Didn't know that.











~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ

Well, if you really had to rev higher, I'd say get a port job as well to have better CFM in those higher RPMs. Doing this on a stock head ported head would probably not gain you anything.

Also, even if you did this, your powerband may shift upwards and you still might not gain any power in the higher RPMs because the secret cams may not support a 6000+ rev. If you WANT to rev that high, I would have suggested having a custom camshaft gring that would support revving that high and actually making power, otherwise, it would be pointless to rev to 7000 when you max in horsepower in the late 5000 range (for example).

How do you plan on bypassing the rev limiter?

Higher revs aren't always what people make them cracked up to be. Our motors have less revs to make more torque than say an Honda motor that can rev 7000+ RPMs. Having a closer powerband is where it's at. What's the point of having an powerband that maxes at 7000 RPMs when it only kicks in at about 4000 or 4500 RPMs (for example)? That means your acceleration is going to be awful because your powerband has shifted so far upwards that it takes even longer to reach it, hence, losing torque and could actually hurt your performance.

That's my take on the subject though...



www.kronosperformance.com / 732-742-8837

My basis for thought was that the secret cams come from a Beretta 2.3L motor, and those cars redlined at 7200 and made power up to that point. That's why I figured that it would do the same with the 2.4L. Is that not true?



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

Luke Heier wrote:My basis for thought was that the secret cams come from a Beretta 2.3L motor, and those cars redlined at 7200 and made power up to that point. That's why I figured that it would do the same with the 2.4L. Is that not true?

You would know more than me. I'm not up to date on the 2.3 or 2.4L motors at all...



www.kronosperformance.com / 732-742-8837

the secret cams come from the 95 2.3 engine and the 90-94 2.3 Lo engine. They don't make power after 5750 rpm. The Gtz cams(witch were the Ho) have peak power at 6200 rpm and have a rev limiter at 6800rpm. The W41 were reving at 7200rpm (7400rpm for the 91) and stop making power at 6800rpm.

So all you want to do is kinda pointless because you won't make more power after 5800rpm.



Gilles
2.3 Ho

So you would recommend to get a port job? Anything else that I should do other than the things I mentioned in the first post? I'm trying a N/A setup. I have pretty much done every external bolt on that there is including the NVG-tranny swap. Now I'm looking at engine internals.



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

Mfk-223 wrote:the secret cams come from the 95 2.3 engine and the 90-94 2.3 Lo engine. They don't make power after 5750 rpm. The Gtz cams(witch were the Ho) have peak power at 6200 rpm and have a rev limiter at 6800rpm. The W41 were reving at 7200rpm (7400rpm for the 91) and stop making power at 6800rpm.

So all you want to do is kinda pointless because you won't make more power after 5800rpm.

Thank you for clarifying it. So my theory stands correct.



www.kronosperformance.com / 732-742-8837

Luke Heier wrote:So you would recommend to get a port job? Anything else that I should do other than the things I mentioned in the first post? I'm trying a N/A setup. I have pretty much done every external bolt on that there is including the NVG-tranny swap. Now I'm looking at engine internals.

Well first, what is your power goal?



www.kronosperformance.com / 732-742-8837

Ahhhhhh, thank you Gilles for the info. I had a buddy here with a Beretta and he redlined at 7200 with his car. I thought he had a regualar 2.3L in it. He must have swapped in a W41 then. I should have asked you first about it. I just assumed that he had the 2.3L HO and that they all redlined at the same point.

So since revving higher won't make a difference with the secret cams, what kind of internals can I start to change that will give me more power?



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

Luke Heier wrote:Ahhhhhh, thank you Gilles for the info. I had a buddy here with a Beretta and he redlined at 7200 with his car. I thought he had a regualar 2.3L in it. He must have swapped in a W41 then. I should have asked you first about it. I just assumed that he had the 2.3L HO and that they all redlined at the same point.

So since revving higher won't make a difference with the secret cams, what kind of internals can I start to change that will give me more power?

Are you purposely trying to stay n/a?



www.kronosperformance.com / 732-742-8837

n/a higher compression , stiffer valve springs , lighter spring retainers , lighter crank , rods , pistons , balancing , mild porting

Yeah, I'd like to stay N/A. I can't afford a turbo setup, but I can progressively buy engine parts.



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

Luke Heier wrote:Yeah, I'd like to stay N/A. I can't afford a turbo setup, but I can progressively buy engine parts.

You'd be suprised how affordable a turbo setup is.



www.kronosperformance.com / 732-742-8837

For a good reliable setup, I'm looking at around $2000, right??



2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R

Luke Heier wrote:For a good reliable setup, I'm looking at around $2000, right??

I'd say about $2500-3000 for everything you want depending on how you buy the parts (new or used), what brand you get and where you get it from.



www.kronosperformance.com / 732-742-8837

check me if im wrong, but i don't believe ANY of our cars' computers have fuel and spark maps for engine speeds above the rev limiter. i also dont know of anyone with a J-body who has actually bypassed their rev limiter. Because of these difficulties, I'd say your best bet would be to go with a standalone Engine Management System... you could get much more power over stock, and accordingly tune fuel and spark for your new cams, and for power ranges above your old rev limiter.

Quote:

i also dont know of anyone with a J-body who has actually bypassed their rev limiter.

well now you know one.....i bypassed My rev limiter on my stock pcm.....

Quote:

I'm trying a N/A setup. I have pretty much done every external bolt on that there is

have you thought about a HO head swap??..if your gonna stay NA

Luke, the 91-94 cluster show 7200rpm but it's 6800rpm in reality. When I swap the dash, the 90 cluster showed 6800rpm and the 91-94 cluster showed 7200rpm with the same ecm.

My 92 Scx ecm is suppose to cut at 7200rpm but at 7800rpm(on the cluster) it keep going.



Gilles
2.3 Ho

first of all... i dont know why anyone is mentioning the oil pump...

The oil pump on the LD9 is chain drivin, right off the crank... its like a supercharger, the faster it spins, the more it pumps. The whole point of the pump is to lube the head... the entire bottom end is lubricated by WINDAGE. Ever noticed that there isnt a windage tray??? Thats why.

Now the only time the pump doenst work is when you dont have enough oil in the system, or really hard left hand turns... this is only because the pick-up is on the driver side of the pan.

Now, revving higher is not really all that good of an idea. There are many things you need to do in order to utilize those extra rpm's.

BOTTOM END

The stroke on these engines are huge... 94mm/ 3.700in. This is the biggest limiter on rpm's. All these litte Honda engines rev way the hell up there because the piston travels around a half inch less on each stroke.

To put things in prospective.... @ 6000rpms, your piston moves from 0, to 141mph, and back to 0 again, all in 3.700 inches. How fast is that??? The world record for the 0-100-0 for a car is held by the Ultima GTR, which did this in 971 FEET.

Now, each piston weigh about 1.25 lbs.... so you have 5lbs of pistons, 4lbs of rods, and a 46lb crank, doing this 0-141-0 in 3.7in... 100 times PER SECOND! Are we starting to get an idea of the forces and pressures that are going on here??? If not, imagin this...

Take 30 Corvettes, stack them all up on top of eachother... and then balance them on a roll of quarters... now put that on top of your connecting rod and you have just successfully simulated what its like to push a 1.25lb piston from 0-141mph in only 1.85in.
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TOP END

Your head is designed in both porting, and in valvetrain to run up to 6500rpm... after that, things start getting ugly.

The headcasting itself actully flexes as you rev. So the higer you rev, the more it flexes. Your head bolts arent designed to handle that... so those need some upgrading. The valve train itself is not strong enough to handel those rpms. The valves can float, the springs can break, the lifters can exploded. All of these things need to be replaced.

Now the fun part... airfow. The ports on the head arent designed to be efficient at those very high rpms. @ 6000 rpms, your look ing somewhere in the neighborhood of 75-80% VE. Doing a proper port job and polishing the correct areas of the head, can increase this efficiency range, allowing good airflow at higer revs. This could extend the VE of the head another 1500-2000rpms if done PERFECTLY.

The cams are the last part. Th duration of the cam is a direct relation to how high the motor can make power in the rpm band. Stock cams run 210/212 degrees of duration... pretty mild. Cams that will make make power higher will be in the 230-250 degrees of duartion. The only set back here is that youll lose your low end snap. People will claim you wont, but you will... the engine has no choice.

So you want to rev higher... build a new engine, then buy a computer to manage it, and try to drive it on the street... if you can manage that, you will be dissapointed. You wil have gained all of 20bhp and spent thousands of dollars and at least a hundred man hours doing it.

Unless your ready to make a race gas only engine, i would suggest working within the 6500rpm range.