How high of a lift cam can fit in a stock 2.4? I need to know for math purposes to figure out max lift on my 086/stock bottom end motor. Thanks.
Not sure about with stock pistons but im running 9.5:1 with valve reliefs, 97 head, and .430/222.
Yeah,
You can basically run any cam that will fit on that 086.
I think mantapart (ut oh) had up to a .430 lift or higher cam available at one point.
Just get the HO cam towers.
Not of course, you'll want to reinfource that bottom end.
And 100% get some kind of tune on your ride.
-M
Remember....syringes go in the RED waste basket.
Thanks that will help a lot. Word has it HO cams wont work with the 086 swap and stock pistons. I do want to build a better bottom end eventually but stock will have to work for now. I have definitely monitored the motor with hp tuners for spark knock, surprisingly theres not too much. I have a wideband but I havn't hooked it up yet. I dont want to do a dyno tune until I upgrade the cams.
I'll shoot you a PM for the specifics on your install.
But you are correct.
Higher lift, the valves are pushing down into the block further, so you goota watch those ratios.
-M
Remember....syringes go in the RED waste basket.
Mastin wrote:Yeah,
You can basically run any cam that will fit on that 086.
I think mantapart (ut oh) had up to a .430 lift or higher cam available at one point.
Just get the HO cam towers.
Not of course, you'll want to reinfource that bottom end.
And 100% get some kind of tune on your ride.
-M
Not likely.
I checked a 2.4 w/.410" lift and 218° duration and had about .25" minimum valve to piston clearance with a flat top piston.
That was with a 2.4 head, not 2.3.
2.3 heads put the valves much closer to the pistons to begin with. Not sure how much, but very likely to be real close to .25" (if not more) closer than the 2.4 head.
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thats a HO cam you checked, right??
paul tjepkes had HO cams on wiseco 10.5:1 pistons (FAR from flat tops) and it worked beautifully. unsure on how much clearance but obviously it was enough because it ran just fine. IIRC he did check to see just how much clearance using some clay on the top of the piston.
Quote:
Not likely.
I checked a 2.4 w/.410" lift and 218° duration and had about .25" minimum valve to piston clearance with a flat top piston.
That was with a 2.4 head, not 2.3.
2.3 heads put the valves much closer to the pistons to begin with. Not sure how much, but very likely to be real close to .25" (if not more) closer than the 2.4 head.
I know its an issue, that's why I said:
Quote:
you'll want to reinfource that bottom end.
-M
Remember....syringes go in the RED waste basket.
what would reinforcing the bottom end have to do with the valves hitting the pistons?????
All 2.4s had pistons without valve reliefs cut into them from the factory.
All 2.4s had large combustion chamber heads with the valve seats set pretty far from the piston.
All 2.3s, no matter which head or camshaft they were equioped with, had valve reliefs cut into the pistons from the factory.
All 2.3 heads, including the 086, had much smaller chambers than the 2.4 and the valve seats are much closer to the piston because of it.
How much lift can a 2.3 head on a 2.4 do without damage?
There isn't enough info in your question to ever answer it. Lift is not the only issue. Valve timing is also an issue and possibly the more important one.
As a rule of thumb, the valves are never open very much, if at all, when the piston is at the top of the bore.
The amount they are open is purely a function of the cams duration and they would never be fully open with the piston at TDC unless the cam is extremely agressive (timing) with a ton of duration. therefore, max lift isn;t the # you need to figure it out.
The only person who can answer this question for you is yourself if you measure it on your setup. Of the probably 3-4 people who have actually checked the clearance themselves that are on this forum, none would likely have your setup or cams, so their tests would not apply to you.
But based on how GM built them (info listed back at the beginning of this) I would be concerned with your hybrid setup because GM seemed to be.
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This was my Idea: if I knew the max lift for a 2.4 (really to know the clearance for the HO, LO, or stock intake cam would work) it will in theory let me figure out my max lift. I have a 2.3 and with a cam I will clearance (with clay) the 2.3 with 2.3 head and also clearance it with my spare 2.4 head. Now in theory if i take the the amount of clearance difference the 2.4 head adds to the 2.3 It should mean the same amount of clearance can be subtracted from my motor. Therefore if I knew how much clearance HO, LO, or stock 2.4 cams have with a stock setup, I should be able to calculate my max lift.
^^^ lol or you could have valve reliefs custom cut into a set of forged pistons. done.
ive personally had an engine that the exhaust valves kissed the stock pistons (stock ld9), so... its close even on a stock ld9.
who gets pistons with Valve reliefs in them!....
*looks at build sheet for my own pistons...*
1.55 pocket Dia, 20* angle .2200 depth Intake, 1.34 Dia, 22* angle, .115 depth from TE.
and thats just for Flat top pistons for a LG0 (HO) Quad-4.......
Pistons and valves, when they meat, valves loose.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
do you mean when they meet the valves LOSE? of course! lol
I know I should get valve reliefs in my pistons when it comes time to get pistons. All I want to know is what the max lift is on a stock LD9 so I can work with what I have right now. Pistons are in the future but not the immediate future. Or how much clearance stock cams have in a LD9. Something I can work with to better what I already have.
