I have a 2.4 with wiesco forged 9-1 pisons. a 2.3 head ported and polished. 2.3 oil pump. Secret cam swap. Ho Intake and exhaust manifold. it was tuned by a decent tuner with HP tuners. We have no access to a dyno or any dyno shops near us. Does anyone care to guess the crank HP or furthermore wheel HP? I understand this is not scientific or anything would just like a good guess please.

well... as not many LD9 with 2.3 head setups exist its hard to gauge.

however, im going with somewhere around 185whp if the tune it spot on with a 5spd and 165-170whp with an auto.

those secret cams are going to hurt.



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What cams would you recommend with out changing my pistons

well see its tricky since you have that 2.3 head on there... im just not so sure HO cams would clear but i think they would...

i know dohc tuner has basically the same setup as you but did have custom valve reliefs cut into his wiseco's.

that would be a good question to ask www.quad4forums.com



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Are most people not using the 2.3 head to make horsepower?

really??? 185whp on 9:1 CR? You realize that's approaching 100bhp/liter on 9:1 compression (actuallly ~90hp/liter)

I'm doubtful, but I'd love to learn i'm wrong.

his compression is way higher than 9:1. the 2.3 head combustion chamber is smaller than an LD9.

when will people realize that pistons are barely half of the equation when counting up compression ratio?



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"way" higher? sorry i'm unfamiliar with the quad/TC head swaps, but how much higher is it? 'Cause I'm thinking about 11-12:1 to make those kind of numbers on the secret cams. Like I said, I'd love to be wrong and this is, after all, just shooting the breeze and speculation. 185whp is ~ 210bhp. That's more than the HO made with more aggressive cams and 10:1 CR. Just sayin

It is somewhere about 11.3 to 1 or 11.5 to 1. I have not did the math but others have.

oldskool wrote:"way" higher? sorry i'm unfamiliar with the quad/TC head swaps, but how much higher is it? 'Cause I'm thinking about 11-12:1 to make those kind of numbers on the secret cams. Like I said, I'd love to be wrong and this is, after all, just shooting the breeze and speculation. 185whp is ~ 210bhp. That's more than the HO made with more aggressive cams and 10:1 CR. Just sayin

i take it you've never heard of paul tjepkes? he made 201whp with around 11:1 compression. and thats with a 2.4 head and stock HO cams.

on stock pistons (depends on what year) the 2.3 head on an LD9 is around 11.7:1 iirc.... and thats with a stock bore, stock dished valves, and stock head gasket. if you bore the block, ups the compression. if you install ss valves, ups the compression, if you deck the head or the block, ups the compression. there are lots of things to consider when calculating the final ratio.

*note, i did say 185 with a SPOT ON tune. not many get there car's dyno tuned, especially all motor cars.



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Brian dynoed back in the day at 171whp if i remember correctly with a very similar build and 9.5:1 slugs. In light of this, I dont see 185whp regardless of how it's justified. And what are stock h. o cams?



Blew it up, build numbers coming soon

actually... brian's pistons were the same as this guys. the dished... aka "9:1"

stock ho cams are .410 / .212.



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Actually, it's not even worth arguing about in this dude's thread

BUT for the record

brian and now jmarks (same motor) runs 40over 9.5:1 weiscos.



Blew it up, build numbers coming soon

Wow you gain ~ 2 points CR with this head swap? Pardon my ignorance, but is this strictly due to the smaller bore, or is the 2.3 head really have that much smaller chamber volume - different shape? (or both)?

LD9Stunner wrote:Actually, it's not even worth arguing about in this dude's thread

BUT for the record

brian and now jmarks (same motor) runs 40over 9.5:1 weiscos.

Yep I agree with this guy!! The motor is quite a bit different now

My guess is 180 with the higher compression and a GREAT tune. The tune is everything. Cams are going to hold back the motor now.

color me lost ld9 stunner...

could you please explain to me how stock compression is 9.5:1 with a FLAT TOP piston and brian's/jmarks motor has "9.5:1" (pistons) when they have a huge dish in them...


ps, im not counting in the overboring at .040. its important for you to know that the pistons themselves (at a stock bore with that dish) are not 9.5:1.




Edited 1 time(s). Last edited Thursday, March 18, 2010 5:37 AM


We all need somebody to believe in something...

It depends if he is running the 96-98 head or the 99-02 LD9 head. The 98-96 head combustion chamber is slightly smaller than the 99-02 heads combustion chamber.......correct? Or am I remembering wrong....









PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

oldskool wrote:Wow you gain ~ 2 points CR with this head swap? Pardon my ignorance, but is this strictly due to the smaller bore, or is the 2.3 head really have that much smaller chamber volume - different shape? (or both)?

Combustion shape has no bearing on static compression raio. But yes, the 2.3L combustion chambers are significantly smaller than the 2.4L. The 2.3L head has a 48cc combustion chamber, while the 2.4L has about a 62cc combustion chamber. The bore by itself is not the issue, it's the displacement. The quad4 displaces 2.26L of air, while the LD9 displaces 2.39L. And you probably already know this, but in case you didn't...

SCR = (Total Volume in cylinder @ BDC) / (Total volume in cylinder @ TDC)

-MD- Enforcer wrote:It depends if he is running the 96-98 head or the 99-02 LD9 head. The 98-96 head combustion chamber is slightly smaller than the 99-02 heads combustion chamber.......correct? Or am I remembering wrong....

I think you are getting senile Mike. A smaller combustion chamber yields a higher compression ratio, because you are lowering the volume that the air is being compressed to. Anyways, the 96-98 had slightly lower compression because it had slightly dished pistons. 99-02 had flat top pistons. As far as I know, all LD9 heads have a ~60-62cc combustion chamber. If there is a difference, it's negligible.

Brad is correct, but I think maybe some are misunderstanding each other. I think some are saying 9.5:1 pistons referenced to the LD9 head (Real SCR ~11.5:1) and some are saying 9.5:1 pistons referenced to the Quad4 head (Real SCR = 9.5:1). In a thread like this, it would be helpful to clearify what you mean.




I have no signiture

well ill try and simplfy it...

the stock pistons either come in flat top or dished. the dished version came with the head that has the protrusion making a factory claimed 9.5:1 ratio. the flat top pistons (99-02) came with the head that lacks this protrusion. so in the end i believe the ratios are pretty much the same do the differences.

now...

picture a flat top piston sitting next to a dished piston. the dished piston is going to provide less compression than that of the flat top.

the 99-02 piston is a flat top. the wiseco "9.1" piston is dished.

see what im getting at? there is no way that wiseco DISHED piston (unless it is oversized) is going to equal that of a stock piston's ratio. unless they came up OUT of the block, which they do not. i have two sets of wiseco's like this and know exactly how they go into the block. ive also got a set of diamond pistons that are nearly identical to those two wiseco sets, only they have valve reliefs.

these '9:1" or mythed "9.5:1" wiseco DISHED pistons everybody buys are actually lowering the compression ratio. if you want to be at stock for stock you need to buy FLAT TOPS. (these are completely flat). if you want higher, you need DOMED (they have massive valve reliefs and have a flat "plateau" of sorts that protrudes UP AND OUT of the block.

three piston styles exist for us:

dished
flat topped
domed

done, end of story. ive personally held all three styles in my hands and have helped install and or owned all of them as well. ive also held in my hands both styles of stock pistons as well as both styles of stock heads. the differences are there, its up to the open minded soul to look at the facts and realize the truth.



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Well Brian calculated what the CR was and came up with 9.3:1 with a .074 cometic head gasket....

yea but wasnt the head decked some? and it had to have had stainless valves....

i could certainly believe that number.



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I have a similiar setup except with the LG0 cams. When my machinist did the measurements he said I did not need valve reliefs. But to be on the safe side I still modified my pistons.

Install some bigger cams than secret cams....these cams will hold you back.

And last do some crank work to squezze out some more power on the power band. Talk to Brad for more info. This is on my list for motor along with other updates.


GMR has got nothing on this

Whalesac wrote:

-MD- Enforcer wrote:It depends if he is running the 96-98 head or the 99-02 LD9 head. The 98-96 head combustion chamber is slightly smaller than the 99-02 heads combustion chamber.......correct? Or am I remembering wrong....

I think you are getting senile Mike. A smaller combustion chamber yields a higher compression ratio, because you are lowering the volume that the air is being compressed to. Anyways, the 96-98 had slightly lower compression because it had slightly dished pistons. 99-02 had flat top pistons. As far as I know, all LD9 heads have a ~60-62cc combustion chamber. If there is a difference, it's negligible.

Brad is correct, but I think maybe some are misunderstanding each other. I think some are saying 9.5:1 pistons referenced to the LD9 head (Real SCR ~11.5:1) and some are saying 9.5:1 pistons referenced to the Quad4 head (Real SCR = 9.5:1). In a thread like this, it would be helpful to clearify what you mean.

I agree on the higher compression....

Brad wrote:the stock pistons either come in flat top or dished. the dished version came with the head that has the protrusion making a factory claimed 9.5:1 ratio. the flat top pistons (99-02) came with the head that lacks this protrusion. so in the end i believe the ratios are pretty much the same do the differences.

What I was trying to say is lets say you have flat top pistion.....no dish no dome, and use the 96-98 head. Wouldn't that yeild higher compression......than the 9.5:1......






PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

^^^ yes, absolutely. shave the head and add in SS valves to the mix... your probably looking at 10.5:1.



We all need somebody to believe in something...

z yaaaa wrote:^^^ yes, absolutely. shave the head and add in SS valves to the mix... your probably looking at 10.5:1.

I'm glad we agree. lol





PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO