Bah, stop rationalizing. You know you want one. Bet Bennie wants to give you a smolin deal on one right now. 11:1 and a 35lb shave might be nice on that motor. :smokin::smokin:
Quench height means very little in 4.0L engines - another myth. I will effectively only have the thickness of the head gasket as my quench height (gaskets vary) as my pistons should be at, or very slightly below zero deck.
In my turbo-charged Jeep - I run pistons with zero quench surface, true inverted domes. Proof that quench in 4.0L engines doesn't mean jack.
Teflon skirts and a ceramic coated top are nice touches (and my turbo motor has both of these), but generally are reserved for forced aspiration applications. The short answer for this engine - no.
Another awesome stroker build Corey! I'm following this one. I like your info on the KB pistons and 4.0 rods. I'm going to have to replace my pistons soon (i reused the stock 4.0 pistons and get piston slap pretty badly on cold start)
Question on that part. When I built my 4.5 stroker, I didn't mill the block or head, and I'm using a stock head gasket. Using the 4.0 rods will lengthen my stroke by how much? I'm just asking so I can figur eout what dish I would need on the Keith Black pistons.
Thanks
Another awesome stroker build Corey! I'm following this one. I like your info on the KB pistons and 4.0 rods. I'm going to have to replace my pistons soon (i reused the stock 4.0 pistons and get piston slap pretty badly on cold start)
Question on that part. When I built my 4.5 stroker, I didn't mill the block or head, and I'm using a stock head gasket. Using the 4.0 rods will lengthen my stroke by how much? I'm just asking so I can figur eout what dish I would need on the Keith Black pistons.
Thanks
We did all the math two weeks ago, and the short answer is that the KB pistons, when used with 4.0L rods and an un-decked head+block offer approximately this compression ratio:
As far as increasing the actual stroke by using 4.0L rods, it is on the order of a few percent. The real increases come from the reduced wall/piston friction and the increased dwell time.
So your saying 4.0 rods with a keith black piston will give a 9.4:1 ratio? HMM that sounds about right for 87 octane which I'm going for. The 4.0 rods I thought were longer, what about TDC won't they be longer? Or is that what the custom pistons are for? Would a decked head and everything also decrease compression?
if you remove any material from the block or head it increases compression unless you open the chambers to offset it. but that's a whole knother ball of wax.
We did all the math two weeks ago, and the short answer is that the KB pistons, when used with 4.0L rods and an un-decked head+block offer approximately this compression ratio:
As far as increasing the actual stroke by using 4.0L rods, it is on the order of a few percent. The real increases come from the reduced wall/piston friction and the increased dwell time.
if you remove any material from the block or head it increases compression unless you open the chambers to offset it. but that's a whole knother ball of wax.
Oh I know that ball of wax. So any material removed it should be minimal just to make sure its even. I need to keep compression as low as I can to keep 87
Forget about quench height, see previous post. But for fun - running the KB's gets you close to a zero deck height. Your head gasket thickness is all you need.
So your saying 4.0 rods with a keith black piston will give a 9.4:1 ratio? HMM that sounds about right for 87 octane which I'm going for. The 4.0 rods I thought were longer, what about TDC won't they be longer? Or is that what the custom pistons are for? Would a decked head and everything also decrease compression?
Yes - the custom pistons (not custom anymore as KB has a part number) enable you to run 4.0L rods with a 258 crank in a 4.0L block. They are longer, hence the need for a shorter pin-height piston.
A decked head raises compression. Generally only recommended if the head is warped unless you like fooling around with pipets, putty and/or graduated cylinders to figure out your compression ratio.
We did all the math two weeks ago, and the short answer is that the KB pistons, when used with 4.0L rods and an un-decked head+block offer approximately this compression ratio:
As far as increasing the actual stroke by using 4.0L rods, it is on the order of a few percent. The real increases come from the reduced wall/piston friction and the increased dwell time.
Wrong: rod length could be 10 foot and the stroke dont know it. You been building long?
In addition, your remarks regarding rod length and dwell time are mechanically impossible. True that a long rod motor will slow the piton at TDC but it speeds it up at BDC instead of what you claim as slowing it up at both ends of the throw.
In closing, I'd direct your attention to the spring pressures you quoted. Admittedly, I dont mess with hyd or flat tappet cams but those spring pressures seem awful low to me. I'd rethink that one and call for a recommendation from Comp. Extra seat pressure makes more power then not enough.
No, I just started building engines this Saturday. :flipoff2: Maybe if you help me with all the details it might actually run? :shaking::shaking:
----punk
I should have defined what I was saying a bit better, I am sort of used to discussing rod angularity, piston speed and "effective" stroke with other 4.0L nerds.
Longer rods increase effective stroke by a few percent, but the power gains come from the piston speeds coming into and leaving TDC and BDC, the increase in dwell time, and the reduced angularity with the cylinder wall (decrease in friction).
:flipoff2:
Wrong: rod length could be 10 foot and the stroke dont know it. You been building long?
In addition, your remarks regarding rod length and dwell time are mechanically impossible. True that a long rod motor will slow the piton at TDC but it speeds it up at BDC instead of what you claim as slowing it up at both ends of the throw.
In closing, I'd direct your attention to the spring pressures you quoted. Admittedly, I dont mess with hyd or flat tappet cams but those spring pressures seem awful low to me. I'd rethink that one and call for a recommendation from Comp.
You got me there. I saw a post claiming rates and pressures that seemed awful low to me at least. I thought it was you stating your spring specs.
For a guy that came on here to dispel myths, you sure are creating some. If I take a 3.5" crank a bolt a 10 ft long rod to it the rod will only rise and fall 3.5". If I take a 3.5 " crank and bolt 1 ft long rod to it it will still only rise and fall 3.5 inches. If I take a 1" rod and bolt it to a 3.5" crank the god damned rod still only moves up and down 3.5 inches. Now show me where you come up with a percentage.
No matter how long you yell or talk about effective rod length or ineffective or, 4.0 or V-8 Its all the same thing, you really don't have a clear understanding of the fundamentals of the rotating assembly.
And I aint going no where until you explain to me how you figured this bullshit out! PUNK
For all you guys asking about quench, keep asking because that is a critical measurement. .040 is the correct quench for the piston he is holding in post 16.
He don't know his quench because he don't know his deck hight "at zero deck or below" so he don't know his comp ratio and never will if he assumes all head gaskets are the same. I suspect he don't no how to measure C/R.
If you kids don't behave, I'll turn this station wagon around and you'll each spend a week in your rooms.
Thought I was done raising kids.
Mind if I ask what the planed RPM range this engine is designed for? And what induction system? Carb, TBI, MPI ?
How come they put the piston pin in the center of the piston? I thought the off set pin helped like the long rod for high RPM stuff?
I could be wrong, haven't built engine in 10 years and the stuff changes, so don't holler at ME, I'm old !
You got me there. I saw a post claiming rates and pressures that seemed awful low to me at least. I thought it was you stating your spring specs.
For a guy that came on here to dispel myths, you sure are creating some. If I take a 3.5" crank a bolt a 10 ft long rod to it the rod will only rise and fall 3.5". If I take a 3.5 " crank and bolt 1 ft long rod to it it will still only rise and fall 3.5 inches. If I take a 1" rod and bolt it to a 3.5" crank the god damned rod still only moves up and down 3.5 inches. Now show me where you come up with a percentage.
No matter how long you yell or talk about effective rod length or ineffective or, 4.0 or V-8 Its all the same thing, you really don't have a clear understanding of the fundamentals of the rotating assembly.
And I aint going no where until you explain to me how you figured this bullshit out! PUNK
Why have you decided to fuck with my build thread? I meant effective length of the stroke - the portion of the stroke where the most power is being made. A longer rod increases that number, by a few percent.
No, it doesn't increase the actual measured stroke. :shaking
For all you guys asking about quench, keep asking because that is a critical measurement. .040 is the correct quench for the piston he is holding in post 16.
He don't know his quench because he don't know his deck hight "at zero deck or below" so he don't know his comp ratio and never will if he assumes all head gaskets are the same. I suspect he don't no how to measure C/R.
I already stated what my compression ratio will be. People who build 4.0L engines generally agree that zero deck is where you want to be, which gives about a 0.040 quench height depending on which head gasket you choose.
I think all you fawk tards who keep regurgitating Dino's info need to actually build an engine and learn something OTHER than his stuff. If any of you have read Corey's turbo thread it should be READILY apparent that he has a clue and then some about how to put together a 4.0L.:shaking: Also, quench isn't that important to a 4.0L engine. If you don't believe that, call the guys at Keith Black or Hescos and they will verify that for you. Lastly, to the guy that doesn't understand rod ratios, go buy an engine building book and have a read! No wonder I hardly post on here anymore because of all the blind leading the blind bullshit that goes on. If you know what you are talking about feel free to chime in. If you don't, STFU and go back to playing with your Hot Wheels cars!!!:mad3:
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