alright here is my questions:

i have a 97 LD9 with a few bolt ons. my engine is getting up there for mileage and i have considered ripping it apart to do a little refreshing and such.

i was toying with the idea of doing some cams and some pistons, all very mild though.

Quote:

a minor update halfway through the 1999 model year that eliminated the EGR, increased the compression ratio from 9.5:1 to 9.7:1, and switched from low impedance fuel injectors to high impedance.

from the

can i use the pistons from the 99+ to get a slightly higher compression? as far as i know, the bore and stroke are the same, its just the 99+ are not dished pistons.

i figure the injectors from the 99+ wont be able to be used because of wiring, but whats the benefit with a higher impedance injectors?

also, ive been doing some reading on the secret cams and am still confused about them because there are so many different ones (W41, 086, etc). are there any that can be used on the LD9 without too much modification? i know the exhaust cam is not a problem, but the intake side is a bitch because of the cam position sensor on some. should i just get after market stage 1 cams instead?

any answers would be great. thanks!



1997 RedR - ZedR

99+ pistons will work on a 96-98 ld9 just fine (and vice versa). Upping the compression by less than a full point really isn't going to do much for performance.

Lastly, I believe the only benefit to high impedence injectors is that they require less circuitry to run, which in itself is a benefit only to the automaker...not you. In turn, there are a variaty of sizes for high impedence injectors. It is difficult, however, to find a wide range of low impedence injectors, even though they are desired in high performance applications.


The secret cams refer to the 95' LO intake cam (because of the cam sensor lobe and the power steering) and the 90-94 LO exhaust cam, because they almost match the Mantapart stage 1 cams exactly. Anything larger than the 90-94 LO (.375") cams only require wider lifters, but stiffer springs are highly encouraged as well. If you are running a quad 4 head too, then you will need reliefs on the intake side of the piston as well if you chose to go with as high of lift as HO or W41 cams (.410").


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"Youth in Asia"...I don't see anything wrong with that.

whitegoose( RedR-ZedR),,
If your going to change the pistons I believe you will need to have your cylinders checked for straightness and hone them. I do not know if the 99+ pistons will work or not? I dont see why they wouldnt though if you plan on doing that just make sure that the rods are the same lengtht and the pistons wrist pins are in the same place as your old ones. However if your going to do this you might as well dish out for some good forged pistons, and raise the compression as much as you want. But if you dont want to do that then you can always have your head and your block decked to help increase your compresion more. There is a limit to how much height you can have taken off before it affects your tensioner. Since you will have your head off you might want to polish the ports it will help especially if you wan to add the secret cam's. Its not hard to do just4 time consuming. There are only two cams that are for the secret cam swap... The intake cam is from a 1995 (only) 2.3L Quad 4 engine.. the eighth digit in the VIN is a letter D. Can be found in 1995 Cavalier Z24's, Sunfire GT's, and Olds Achievas. Brand new, it's
--->GM part #24574239($197.64). If you're looking under hoods, the casting number on the cam is 245/742 (which IS the same number as the 2.4L LD9, but has 0.360" of lift), and the casting number on the cam housing/carrier is 24574057.

The exhaust cam is from a 1990-94 (only) 2.3L Quad 4 engine.. VIN D as well. Can be found in 90-94 Grand Am's, Olds Cutlass, Calais, Acheiva, and Buick Skylark. Brand new, it's
Melling MC832 from Autozone

--->GM part #24570698 or #22545390 (a little confusion there)($197.64). The cam casting numbers are 255/455 (which IS the same number as the HO cams, but only has 0.3750" of lift, not 0.410"). <------This is copied from the secret cam sticky....
24574239 Intake camshaft for LG0(95 2.3DOHC)
22545390 Exhaust cam for LD2(Pre-95 2.3DOHC) Are the two I believe you need.

AS far as impedence goes for your injectors I wouldnt mess with it unless you plan on changing the ecu to a 99+ ecu. I dont think them having higher impednce will have a benefit over lower impedence.

Brian Whalen wrote:If you are running a quad 4 head too, then you will need reliefs on the intake side of the piston as well if you chose to go with as high of lift as HO or W41 cams (.410").

Since when do you need reliefs for HO cams?



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

the 95 2.3 is neither LO or HO. its just a 2.3, the only year of this exact particular engine which makes finding the intake a bit difficult, although they are readily available on car-part, but just make sure that you check the lobes of the one you get, i had to go through 3 different ones off that website before i finally got one that was worth a damn and wasnt ruined.

the last time i checked about trying to purchase a set of replacement 99.5-02 pistons they were unavailable through parts houses, other than GM itself and for the money they want for a set you might as well get a set of forged. you can however find a set of brand new 96-99.5's at basically any place for around $150.00 a set IIRC.

the ONLY difference in the pistons are the 96-99.5 have a TINY dish right in the center, very hard to see unless you've got it in your hand. the 99.5-02's are completly flat. there were no other differences other than that dish, the newer pistons upped the compression only slightly.



Edited 1 time(s). Last edited Monday, November 26, 2007 11:57 AM

Luke Heier wrote:

Brian Whalen wrote:If you are running a quad 4 head too, then you will need reliefs on the intake side of the piston as well if you chose to go with as high of lift as HO or W41 cams (.410").

Since when do you need reliefs for HO cams?

Since OLDS put them there stock in the HO motors. If you run the HO intake cam on the LD9 head you will be fine as far as valve clearance. Otherwise, with a 955, 456 or 086 head, you will need reliefs on the intake side or perhaps a dish.

brodycog wrote:whitegoose( RedR-ZedR),,
If your going to change the pistons I believe you will need to have your cylinders checked for straightness and hone them. I do not know if the 99+ pistons will work or not? I dont see why they wouldnt though if you plan on doing that just make sure that the rods are the same lengtht and the pistons wrist pins are in the same place as your old ones. However if your going to do this you might as well dish out for some good forged pistons, and raise the compression as much as you want. But if you dont want to do that then you can always have your head and your block decked to help increase your compresion more. There is a limit to how much height you can have taken off before it affects your tensioner. Since you will have your head off you might want to polish the ports it will help especially if you wan to add the secret cam's. Its not hard to do just4 time consuming. There are only two cams that are for the secret cam swap... The intake cam is from a 1995 (only) 2.3L Quad 4 engine.. the eighth digit in the VIN is a letter D. Can be found in 1995 Cavalier Z24's, Sunfire GT's, and Olds Achievas. Brand new, it's
--->GM part #24574239($197.64). If you're looking under hoods, the casting number on the cam is 245/742 (which IS the same number as the 2.4L LD9, but has 0.360" of lift), and the casting number on the cam housing/carrier is 24574057.

The exhaust cam is from a 1990-94 (only) 2.3L Quad 4 engine.. VIN D as well. Can be found in 90-94 Grand Am's, Olds Cutlass, Calais, Acheiva, and Buick Skylark. Brand new, it's
Melling MC832 from Autozone

--->GM part #24570698 or #22545390 (a little confusion there)($197.64). The cam casting numbers are 255/455 (which IS the same number as the HO cams, but only has 0.3750" of lift, not 0.410").

Decking the block or head on an OHC motor for the sole purpose of raising compression is a terrible idea. Do it right the first time by changing the shape of the piston.


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"Youth in Asia"...I don't see anything wrong with that.