I was wondering what the max amount you could CC out combustion chambers on a 4.0, i kno the stock is 58CC's and ive seem people go out to 60CC's without any issues but i was wondering if 64CC's would be attainable without worrying about water jackets, ect.

Hellooo hellooo hellooo... Is there anybody out there there there

well your question is a bit confusing. ive never heard the term "CC out and engine".

last i checked the 4.0 was a 3960 cc motor meaning what 660 cc per cylinder?

anyway the 4.6 strokers are overbored 0.030-inch the rest being done by increasing the stroke. i dont know about going any further then that.

Step away from the motor dude. Whoever told you that you would be seeing any noticable gains by boring out your cylinders like that lied to you.

Why you would waste money on a 4.0 on anything other then a stroker kit is beyond me anyways. They all peak in the same horsepower range whether you spend 1500 or 10,000 dollars on them.

I could be wrong, but I think the OP is talking about machining out just the combustion chamber(just the head, and NOT the bore of the cylinder)?
if that is the case, all you're really going to do is lower the compression ratio, so unless you're planning other mods(like a turbo/super charger), you're not going to see any gains, would probably actually see a loss of power.

well if your just planning on building the head take it to a shop with a flow bench. they will keep going til they show no more improvement. though i doubt you will get much more then the stock h.o heads and youd be spending much more money. unless your a pro engine builder its just not worth doing. judging by your question your not so go buy a stroker or a 5.3

I could be wrong, but I think the OP is talking about machining out just the combustion chamber(just the head, and NOT the bore of the cylinder)?
if that is the case, all you're really going to do is lower the compression ratio, so unless you're planning other mods(like a turbo/super charger), you're not going to see any gains, would probably actually see a loss of power.

you had it about right... was looking into supercharging. i just figured i could just get a straight answer if i asked a simple question and not deal with people trying to change my mind (which is a waste of their time to be honest). i thought the question was worded well enough for everyone to understand... but hey 1 out of 3 aint to bad...

well your question is a bit confusing. ive never heard the term "CC out and engine".

last i checked the 4.0 was a 3960 cc motor meaning what 660 cc per cylinder?

anyway the 4.6 strokers are overbored 0.030-inch the rest being done by increasing the stroke. i dont know about going any further then that.

its prob best not to quote something if it wasnt said i wrote "CC out combustion chambers"...

well i thought it was worded well enough for everyone to understand... where did i hear that before?

either way it doesnt make sense to say cubic centimeter out a combustion chamber. im just sayin.

but it still brings me back to what i said. go do it! start at 60 and test.

(1) well i thought it was worded well enough for everyone to understand... where did i hear that before?

(2)either way it doesnt make sense to say cubic centimeter out a combustion chamber. im just sayin.

(3) but it still brings me back to what i said. go do it! start at 60 and test.

(1) i dont know where you hear that before.... i really dont.
(2) the concept is cc out, to take out cc's from the combustion chamber... sry
(3) after looking back on it i know ive seen 2 diff guy go up to 62cc's on a head before.. but point noted. that was the plan unless someone knew otherwise.

I understand the question. I'd say you may also look into machining a dish in your pistons if there's enough meat there.:D

ya that was a thought but was going to run forged pistons and didnt want to dish them if i didnt have to, they cost a lot and take a good bit of time to get if whoever machines them screws up. i could just get another head in a few hours....

i thought the question was worded well enough for everyone to understand... but hey 1 out of 3 aint to bad...
lol you said it. i was messin with ya. oh and i should have known better that the combustion chamber is the area inside the head not the full cylinder. havent built a motor in awhile...lol

Have you run the numbers? Is 6cc going to get you where you want to be as far as compression ratio? Usually when someone CCs the heads, they only finish them out to the largest one so they are all equal. You don't really hear about people hogging out the combustion chamber to alter compression ratio. If you are spending so much on pistons, why can't you get them in a configuration that will yield the correct ratio? Also, make certain you run the numbers of YOUR parts to determine actual ratio, advertised ratio is never real for pistons.
Travis..

Put down your die grinders now. You do not want to increase the combustion chamber on the 4.0. You will lower the compression ratio and effectively decrease your torque. You will increase flow on the top end and maybe add some power, not what you want to do.

I assume you want to off-road which I don't know much about, but I've been a few times and I've never seen anyone get above 3k crawling over rocks... This would be bottom end. So you want bottom end power and torque, correct? All you must do is blend the ports and work the valves to allow more air to flow at all levels of lift, this will give you bottom end. Keep the compression the same, maybe even up it with oversized non-recessed pistons.

If you do this you'll gain a bit of torque and probably not much power, but your torque will come instantly off idle where you need it, not at 3 or 4k where you won't spend much time.

If you're climbing hills or something and want more power overall then I apologize for wasting your time, but you should stop wasting your time on the 4.0 and get something setup for that.

Have you run the numbers? Is 6cc going to get you where you want to be as far as compression ratio? Usually when someone CCs the heads, they only finish them out to the largest one so they are all equal. You don't really hear about people hogging out the combustion chamber to alter compression ratio. If you are spending so much on pistons, why can't you get them in a configuration that will yield the correct ratio? Also, make certain you run the numbers of YOUR parts to determine actual ratio, advertised ratio is never real for pistons.
Travis..

i hear ya on that one i know this isnt really the norm but its certainly not unheard of.. and ya 6CC's will put me right in the higher end of where i want to be which is just under 9.0:1., also the pistons are over the counter type and i couldnt even increase the dish on these pistons if i wanted to because the pistons are already maxed out which i just found out so i would need to go custom which are much more expensive...

Put down your die grinders now. You do not want to increase the combustion chamber on the 4.0. You will lower the compression ratio and effectively decrease your torque. You will increase flow on the top end and maybe add some power, not what you want to do.

I assume you want to off-road which I don't know much about, but I've been a few times and I've never seen anyone get above 3k crawling over rocks... This would be bottom end. So you want bottom end power and torque, correct? All you must do is blend the ports and work the valves to allow more air to flow at all levels of lift, this will give you bottom end. Keep the compression the same, maybe even up it with oversized non-recessed pistons.

If you do this you'll gain a bit of torque and probably not much power, but your torque will come instantly off idle where you need it, not at 3 or 4k where you won't spend much time.

If you're climbing hills or something and want more power overall then I apologize for wasting your time, but you should stop wasting your time on the 4.0 and get something setup for that.

please read the whole thead before posting... i have plans of supercharging which requires lower compression.

The OP is right on track. I fully understand where he is going with this.

To the OP,

There is another option with going with custom pistons just for forced induction applications. I forget the company but I will find it and get back. I am looking at these pistons along with forged rods to build a bored out 2.5 running a turbo at 15 pounds. This is my next build. There is this thread you should read. It covers a build up for a 4.7 liter turbo motor:
http://www.pirate4x4.com/forum/showthread.php?t=614289

I know your doing an SC, but forced induction is forced induction.
The build covers an engine build of a 4.7 liter stroker specifically to run a turbo capable of 15 pounds of boost.

And don't listen to the naysayers. thier just envious that they don't know how to figure it out on thier own. So they go the easy route and drop in a crate motor which I myself think is boring.

. . . . .

If you're climbing hills or something and want more power overall then I apologize for wasting your time, but you should stop wasting your time on the 4.0 and get something setup for that.


Thats wierd:confused: My T.C.'d 4.0 will plant my in seat when I get it. I find I rarely go past 1/2 throttle on acceleration and it still will scoot like nothing before. You know whats better then having 190HP at 5200 rpm? Its having 190 HP at 2000 rpm at 6 pounds of boost:smokin:

Oh yeah, these motors are capable of 450 hp and 600+ ft/lb torque when built right. Im sitten around 350 now. But I have seen the truth, its possible. Besides, we want torque.

Maybe I missed it and someone suggested it already, but how about some shorter connecting rods?

jpfrk2001 yes ive seen that thread and yours, i got most of my respectable info from the two of your threads. as to the pistons are you thinking of the hescos with the 8.0:1 compression? ive thought a lot about those but still wanted more compression seenings how i dont think i want to go crazy with boost (im sure that will change tho). i look forward to seeing that 4banger build thanks

82FB i have a set quench i want and that being said the only other way to lower compression is to take CC's out of either the combustion chamber or the dish of the piston...

I just got a PM back:

The pistons are available through Hesco. Got to talk to Bennie. The actual manufacture of the pistons is made by Diamond.
http://www.diamondracing.net/products.asp

Here is the Hesco link:
http://www.hescosc.com/shop.asp?action=details&inventoryID=44910&catId=7569

Bad thing for me, I only need 4 of em.