I am wondering if you use a LD9 bottom end and a 2.3 head do you need valve reliefs?? I remember a couple of people a few years ago that put a 2.3 HO cams and head on a stock LD9 bottom end without valve issues. Has anyone checked this or just going on the assumption that the 2.3 pistons have valve reliefs and that the new ones will as well

It seems the last couple of builds on the JBO people have had valve reliefs on their pistons




Shorthands



Thrice's pistons





Jason
99 Z24 Supercharged
157hp/171tq - NA
190hp/170tq @ 6psi

LG0/LD9 for Life

To my knowledge no one has actually taken real measurements to find out. One person claimed to have done it with stock LD9 pistons but really showed no proof. I eventually plan on doing this but it will be a while. I want to see some real numbers since I plan on running a crane intake cam

i was gonna test it but ive got no time and im down at college away from my motors.

LG0 slugs do have valve pockets and the block has a 0 deck height which the LD9 block and LG0 block have in common.

The 086 head is a much smaller CC compaired to the LD9's head which puts the valves closer to the pistons as it is.

I don't remember exactly but i believe the head dimensions for the 086 combustion chamber is 48CC versus the LD9's 56CC (or something) So there's a lot more room to play with in an LD9 head and big cams.

Don't forget Headgasket thickness plays a large role as well, stock LD2/LG0 engines had a .043" thick headgasket while the LD9 only has a .030" thick headgasket.

So to use H.O. or W41 cams on an LD9 head is fine, but H.O. or W41 cams in a 086 head on a stock LD9 block/internals WITH AN OEM .030" THICK HEADGASKET will 100% make piston-valve contact.

there is a thread that I myself have posted in several times, on Q4F about this same thing. Here's the LINK

I forgot to mention, I myself am running HG2 cams which are 224 .430 and are ass loads bigger then H.O. or W41 's, so i REALLY need the extra valve room.

AND, there are some cases in which some LD2/LG0's valves to piston spacing is so close even on the stock motor, that valves have grazed the pistons on an engine that has never been taken apart. They don't give you alot of room for error so imagine having even LESS room for error on the flat top pistons in the LD9.

Sounds like you will need at least a .74 Cometic headgasket




Jason
99 Z24 Supercharged
157hp/171tq - NA
190hp/170tq @ 6psi

LG0/LD9 for Life

I put a '95 2.3l head on a 2.4 a few years ago and it ran for awhile... no contact pistons to valves..

So it is possible without..yes.. BUT i don't know the technicalities for it, I just did it..
Actually Gmanz bought the engine from me..

RyZ96 wrote:I put a '95 2.3l head on a 2.4 a few years ago and it ran for awhile... no contact pistons to valves..

So it is possible without..yes.. BUT i don't know the technicalities for it, I just did it..
Actually Gmanz bought the engine from me..

I know it can be done with the secret cam swap, but HO and W41 is going to be close.




Jason
99 Z24 Supercharged
157hp/171tq - NA
190hp/170tq @ 6psi

LG0/LD9 for Life

RyZ96 wrote:I put a '95 2.3l head on a 2.4 a few years ago and it ran for awhile... no contact pistons to valves..

So it is possible without..yes.. BUT i don't know the technicalities for it, I just did it..
Actually Gmanz bought the engine from me..

ya you had the secret cams in that motor. im running W41's in my car now and i will not be putting a 2.3 head on untill i find some pistons i want with the valve reliefs

Blwn LD9 wrote:Sounds like you will need at least a .74 Cometic headgasket

I have reliefs AND .075" thick headgasket but i am taking my pistons to have the valve pockets cut much deeper. I want to weed myself away from the .075" since it won't fair well with high boost.....which, this time next year i'm aiming for 20psi through a Bullseye S362 with .7 A/R and 8,100 redline ...but shhhhh lol

RyZ96 wrote:I put a '95 2.3l head on a 2.4 a few years ago and it ran for awhile... no contact pistons to valves..

So it is possible without..yes.. BUT i don't know the technicalities for it, I just did it..
Actually Gmanz bought the engine from me..

That was also a '95 head. The geometry of that head is much different than the 086 (1990-1992 is the head i'm refferring to)

You probably could have gotten away with H.O's in that head...but don't quote me on that.

Thrice . wrote:

RyZ96 wrote:I put a '95 2.3l head on a 2.4 a few years ago and it ran for awhile... no contact pistons to valves..

So it is possible without..yes.. BUT i don't know the technicalities for it, I just did it..
Actually Gmanz bought the engine from me..

That was also a '95 head. The geometry of that head is much different than the 086 (1990-1992 is the head i'm refferring to)

You probably could have gotten away with H.O's in that head...but don't quote me on that.

While that head shares the water outlet of the 2.4 and the conical spring design the combustion chamber is still the smaller 40cc of the earlier quad. Im positive it would have the same piston valve clearance as the 086. The only difference i can think of is it has slightly smaller valves which means it has sligtly more clearance.

I have a "Decked" 086 head with LG0 Cams on my LD9. My wiesco's originally came with a dish and I had some valve reliefs put in. They were not big pockets either. I started and have had the engine running and revving without a tune (under 3k RPM) and the pistons have not meet the valves (Knock on wood).

The Quad 4 water outlet has about 4 openings so you will need to plug up two of them including one on the head. You will use two only on the water outlet. One for the sensor and one for the coolant tank hose line.

GMR has got nothing on this

Sorry, like I said I didn't know the technicalilties of it. OP wanted to know if the 2.3 head on a 2.4 bottom end was okay.. In my case yes it was