318 build

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Hughes claims to up the compression adding there cams the cam came with two pieces of paper giving instructions and cam card but they was howards cams logo on the paper that was with the hughes cam anybody had that happen to them
Howard's Cams grinds the cams for Hughes
 
That’s because the math says that’s the MINIMUM hp gain to be expected.

You certainly gain more than that if the cam, headers and induction is optimized.

The other thing is for all the crying and whining that 10 hp doesn’t matter (sometimes it doesn’t) that guys don’t understand that 99% of the engine dynos in use today can’t measure the engines ability to gain rpm.

That’s a concept many overlook.

You may only gain X percentage the dyno doesn’t tell the whole story.

It can’t tell you how well the engine takes the clutch off the two step (or the converter for those guys that wear dresses…just kidding, I know they don’t wear dresses just because the have an automatic) or how well it does at the bottom of the gear changes or even off the throttle stop.

It doesn’t measure that. But it damn sure makes a difference at the track.

And for all the “it’s not a race car” guys, you still have to get away from stop lights don’t you? You still shift the car (even more critical for us there pedal guys) don’t you?

I won’t even get into expansion ratio and how much harder the higher compression pulls on the boosters.

All this and more is why I advocate for guys to run as much compression as they can tune for. Whatever that is.

And then spend some time learning how to tune for “unorthodox” compression ratios.

Some things you can do with unorthodox compression ratios is running the engine temperature like your Honda. It needs to run colder than that. Over 11.5:1 or so you need to beat 160 and be able to maintain that temperature. If you can’t do that lower the compression ratio.

You absolutely must run a timing curve. That doesn’t mean it’s all in by 2500 or even 3000 rpm. It needs to be a curve.

And some other stuff I don’t feel like typing out right now.

Compression makes things better.
No one is arguing against the effect's of CR, but this argument always comes up especially with mild 318 hop ups, someone has a running 318 and wants to add 4bbl cam exhaust and tune to it then the CR police badger them that it can't be done without addressing the CR. Of course CR gonna make it better but it's not always an option and there no reason you can't make power with less CR.

Sounds like the OP is rebuilding this 318 so yes he should be addressing the CR issue if he already hasn't.
 
Effective compression ratio and dynamic compression ratio are NOT the same.

Treating them the same just muddy’s the water.

It’s EFFECTIVE COMPRESSION RATIO that counts, and it’s easily calculated.

DCR is not and confusing the two is bad news.

"

take the stroke from that position to calculate the “effective” cylinder volume (“VE”), which is amount trapped by the closed intake valve; which is always less than the nominal volume (“VN”). Using this, calculate the effective compression ratio (“CRE” ); also lower - the combustion chamber volume is unchanged, but the cylinder volume is less."

which is part of the calculation for DCR you work out how much could conceivably be compressed after the intake has closed then you take into account LSA inlet closing angle rod length and stroke.

i.e you use the CRE in a basic calculation that avoids having to deal with volumetric efficiency




not exactly the same....
neither is dynamic
neither changes
neither takes VE or RPM into account
neither can be applied to a running engine as they are calculated from bog standard dimension and timings that pay no heed to RPM or flow

both come up with a figure that is better than assuming a full sweep of the cylinder volume is a useful indicator of CR. that doesn't give a true indicator of what is being compressed and what is being chuffed down the exhaust or back up the inlet.
both assume perfect situation which can only exist at 0 rpm

id say there is a fair amount in common

Dynamic compression ratio, its the name that causes problems... the internet is full of rubbish on this... total crossed wires attributing way more to it than is possible.

regardless of what it is called, the mathematical outcome is useful

it will help the OP work out if his cam is useful or a complete liability based on the data he can measure or get from the shop manual for his 318 and his cam card

he has all he needs
if he comes back with 7.4--7.9 he gets a thumbs up from me....all will be well
if he comes back with 9.... id say get a different cam

it is absolutely a measure for this situation, perfect tool to help if you have some idea of what you are trying to achieve. parts in hand , are they right? they seem right? they seem to fit with recommendations. Gimme a number to put my mind at rest that i am not going to build an Intransigent Pinging bastard of a motor. everybody knows someone who did....

in isolation its a useless number....

i.e real low CR and one cam or real high CR and another can give you the same DCR. two motors with very different personalities

its useful if you want to know which way to move when you have a nearly ok combination of parts
slightly longer duration different LSA. would a big fat copper gasket give me a little more margin for sustained high speed street driving, do i want to risk losing any kind of quench or should i change the cam

That kinda thing

Dave
 
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"

take the stroke from that position to calculate the “effective” cylinder volume (“VE”), which is amount trapped by the closed intake valve; which is always less than the nominal volume (“VN”). Using this, calculate the effective compression ratio (“CRE” ); also lower - the combustion chamber volume is unchanged, but the cylinder volume is less."

which is part of the calculation for DCR you work out how much could conceivably be compressed after the intake has closed then you take into account LSA inlet closing angle rod length and stroke.

i.e you use the CRE in a basic calculation that avoids having to deal with volumetric efficiency




not exactly the same....
neither is dynamic
neither changes
neither takes VE or RPM into account
neither can be applied to a running engine as they are calculated from bog standard dimension and timings that pay no heed to RPM or flow

both come up with a figure that is better than assuming a full sweep of the cylinder volume is a useful indicator of CR. that doesn't give a true indicator of what is being compressed and what is being chuffed down the exhaust or back up the inlet.
both assume perfect situation which can only exist at 0 rpm

id say there is a fair amount in common

Dynamic compression ratio, its the name that causes problems... the internet is full of rubbish on this... total crossed wires attributing way more to it than is possible.

regardless of what it is called, the mathematical outcome is useful

it will help the OP work out if his cam is useful or a complete liability based on the data he can measure or get from the shop manual for his 318 and his cam card

he has all he needs
if he comes back with 7.4--7.9 he gets a thumbs up from me....all will be well
if he comes back with 9.... id say get a different cam

it is absolutely a measure for this situation, perfect tool to help if you have some idea of what you are trying to achieve. parts in hand , are they right? they seem right? they seem to fit with recommendations. Gimme a number to put my mind at rest that i am not going to build an intransigent Pinging bastard of a motor.

in isolation its a useless number....

i.e real low CR and one cam or real high CR and another can give you the same DCR. two motors with very different personalities

its useful if you want to know which way to move when you have a nearly ok combination of parts
slightly longer duration different LSA. would a big fat copper gasket give me a little more margin for sustained high speed street driving

That kinda thing

Dave


I’m not typing a bunch of **** out but you can’t calculate “dynamic” anything with a ton of information.

Like rpm, load, EFFECTIVE COMPRESSION RATIO, MAP, fuel and whatever else.

You are using the wrong term.

Let me say it this way.

You can calculate static compression ratio by simple math.

You can calculate effective compression ratio by simple math.

If you know the SCR you can calculate ECR.

Effective compression ratio is what the engine sees and it’s NOT dynamic.

Maybe we need to get a dictionary and look up the definition of dynamic and effective.

There is a reason why there are two different words because they are two entirely different things.
 
I didn't come up with the name, :) don't shoot the messenger, I agree totally with your sentiments on this, dynamic is the wrong term for what it actually is

but thats is what its called, I can't help that...
We can agree ..... stupid name.

dynamic and effective are indeed two different words meaning different things ....yeah i know.....

The effective compression is used in calculating the dynamic CR and V/P index

V/P doesn't have exclusive rights to effective compression ratio...... it can be used elsewhere by other people doing other things at a much simpler level.

Dave
 
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I didn't come up with the name, :) don't shoot the messenger, I agree totally with your sentiments on this, dynamic is the wrong term for what it actually is

but thats is what its called, I can't help that...
We can agree ..... stupid name.

dynamic and effective are indeed two different words meaning different things ....yeah i know.....

The effective compression is used in calculating the dynamic CR and V/P index

V/P doesn't have exclusive rights to effective compression ratio...... it can be used elsewhere by other people doing other things at a much simpler level.

Dave

No, we don’t agree. They are two distinct, different things and you are using the terms like they are interchangeable.

They are not.

But let’s play a game. I’ll use my numbers.

My SCR is 12.2:1.
My ECR is 9.5:1.
My IVC is 71 degrees.

Pump gas.

Calculate my DCR at 1000rpm, 3000 rpm, 5000 rpm and 6500 rpm.

That’s idle, in town cruise rpm, peak torque and shift rpm.

Show me my DCR.

TIA
 
Well, all I can say is this
With an Ica of 60*, the cylinder pressure in OP's 318, according to the Wallace, could vary from
142 @ 8.6 to
164 @ 9.6
186 @ 10.6
209 @ 11.6

I've been to 195CCP at least, with a Hughes HE2430AL, and I can tell you that it was insanely much fun. But too much for a Manual Trans to drive slow with.
If I was stuck with a 318, I'd go for pressure.
and since I'm not gonna commit to running best gas, read expensive, ALL the time, why would I run iron heads at 9.6/1.
No, I'm gonna target 200psi with alloy and run 87E10, for which I can buy gas anywhere/anytime.
And BTW
Show me a 318 with a 2336Whiplash cam, in at 102, that can make 340 ftlbs at 3500, with 8.6/1 Scr, which is the recommended maximum compression ratio for that cam.
And, Tell me about VE at 3500 @ 8.6Scr... with , .506lift Whiplash-cam, and stock bigport heads no less.
340 ftlbs? Yeah right.
And even if it did, 340 ftlbs sux period, cuz ;
1) that is the same as a stock 1969 318 2bbl was rated at. and
2) And for the amount of money OP is spending.... it really really sux.


But, what do I know;
I'm just a guy that drives 90 minutes to the track, runs a 106 with a 223cam, and drives it back home, at 32mpg, geared for 65=1600; she was my DD. And, with the next bigger cam, she ripped off a 93 in the Eighth.
So you know, Willrun gets the glory, and I get the chitstains. I should be used to it by now.

Op
good luck, I stand by what I said.
 
Dynamic compression ratio, its the name that causes problems... the internet is full of rubbish on this... total crossed wires attributing way more to it than is possible.

regardless of what it is called, the mathematical outcome is useful
Exactly right. It’s the different names and terms that cause the problems for people. DCR, ECR whatever you want to call it, (ECR is more correct) is useful, important info just like SCR is.

They’re both just ‘static’ numbers so it’s not the be all, end all. But that info does allow you to make more informed decisions on camshafts, cyl.heads, fuel, etc. It all plays its part in the bigger picture.

To accurately calculate cyl.pressure dynamically, you would need to know so much info at each step of RPM (VE, air & fuel flow, exhaust flow,specific density, temperature,and on and on!). The regular hot rodder will never have the ability and resources for that!
 
Well, all I can say is this
With an Ica of 60*, the cylinder pressure in OP's 318, according to the Wallace, could vary from
142 @ 8.6 to
164 @ 9.6
186 @ 10.6
209 @ 11.6

I've been to 195CCP at least, with a Hughes HE2430AL, and I can tell you that it was insanely much fun. But too much for a Manual Trans to drive slow with.
If I was stuck with a 318, I'd go for pressure.
and since I'm not gonna commit to running best gas, read expensive, ALL the time, why would I run iron heads at 9.6/1.
No, I'm gonna target 200psi with alloy and run 87E10, for which I can buy gas anywhere/anytime.
And BTW
Show me a 318 with a 2336Whiplash cam, in at 102, that can make 340 ftlbs at 3500, with 8.6/1 Scr, which is the recommended maximum compression ratio for that cam.
And, Tell me about VE at 3500 @ 8.6Scr... with , .506lift Whiplash-cam, and stock bigport heads no less.
340 ftlbs? Yeah right.
I would if I knew of one, how about you show us one scrap of evidence that 3,500 rpm is gonna be decimated other than your assumptions.
And even if it did, 340 ftlbs sux period, cuz ;
1) that is the same as a stock 1969 318 2bbl was rated at. and
2) And for the amount of money OP is spending.... it really really sux.
Yes 340 lbs-ft is low why I picked it, most built 318's seem to dyno 360-380 ish at 3,500 rpm, even if it dyno'd a very low 300 lbs-ft @ 3,500 rpm that's still 200 hp, 200 hp is not enough power to accelerate from ?
But, what do I know;
I'm just a guy that drives 90 minutes to the track, runs a 106 with a 223cam, and drives it back home, at 32mpg, geared for 65=1600; she was my DD. And, with the next bigger cam, she ripped off a 93 in the Eighth.
There's a ton of dyno result's out there show any evidence that validates what you say.

So you know, Willrun gets the glory, and I get the chitstains. I should be used to it by now.
Cause 318willrun has evidence backing up what he say's, you provide zero for your position, not one scrap of it and when people show you evidence against what your saying, do you revaluate, No! you just ignore and say your being picked on.

Op
good luck, I stand by what I said.
I'm not trying to pick on you but some people are making decisions based off what you say.
You can have your opinion, but it's how you try to wrap it up like it's scientific fact, when it's just based on your opinion with faulty assumptions and scenarios and unwilling to back it up with proof or even debate it's merits.

We get you don't like 318's especially low cr ones, doesn't mean you got to make it your life's mission to discourage others.
 
Exactly right. It’s the different names and terms that cause the problems for people. DCR, ECR whatever you want to call it, (ECR is more correct) is useful, important info just like SCR is.

They’re both just ‘static’ numbers so it’s not the be all, end all. But that info does allow you to make more informed decisions on camshafts, cyl.heads, fuel, etc. It all plays its part in the bigger picture.

To accurately calculate cyl.pressure dynamically, you would need to know so much info at each step of RPM (VE, air & fuel flow, exhaust flow,specific density, temperature,and on and on!). The regular hot rodder will never have the ability and resources for that!


See post 32.

Calculate that for me please.

TIA
 
But, what do I know;
I'm just a guy that drives 90 minutes to the track, runs a 106 with a 223cam, and drives it back home, at 32mpg, geared for 65=1600; she was my DD. And, with the next bigger cam, she ripped off a 93 in the Eighth.
So you know, Willrun gets the glory, and I get the chitstains. I should be used to it by now.

AH-HAHAHAHHA HAHAHHAH HAHAHHA HAHAHHAHAH AHHAHAHHAH

*deep breath*

HAHAHHAHAHAHAHHAHAH AHAHAHHAH AHHHHAHAHAHHAHAHA

*passes out from lack of oxygen*

*wakes up some time later*

*reads post again*

AHAHAHAH HAHA AHAHAHAHHAHAHHAHAAH

*wipes tears from eyes*

you must work for burger king serving up whoppers like that.
 
Cause 318willrun has evidence backing up what he say's, you provide zero for your position, not one scrap of it and when people show you evidence against what your saying, do you revaluate, No! you just ignore and say your being picked on.


I'm not trying to pick on you but some people are making decisions based off what you say.
You can have your opinion, but it's how you try to wrap it up like it's scientific fact, when it's just based on your opinion with faulty assumptions and scenarios and unwilling to back it up with proof or even debate it's merits.

We get you don't like 318's especially low cr ones, doesn't mean you got to make it your life's mission to discourage others.
careful, he's gonna say you're unchristian for calling him to the floor for what he's said.

but you called it. haters gonna hate. zero proof. everything viewed thru a "performance first" or "acceleration in the 1/8th or whatever" lens.

the inability to understand that sometimes "decent" is good enough, not everything has to be perfect.
 

Well, all I can say is this
With an Ica of 60*, the cylinder pressure in OP's 318, according to the Wallace, could vary from
142 @ 8.6 to
164 @ 9.6
186 @ 10.6
209 @ 11.6

I've been to 195CCP at least, with a Hughes HE2430AL, and I can tell you that it was insanely much fun. But too much for a Manual Trans to drive slow with.
If I was stuck with a 318, I'd go for pressure.
and since I'm not gonna commit to running best gas, read expensive, ALL the time, why would I run iron heads at 9.6/1.
No, I'm gonna target 200psi with alloy and run 87E10, for which I can buy gas anywhere/anytime.
And BTW
Show me a 318 with a 2336Whiplash cam, in at 102, that can make 340 ftlbs at 3500, with 8.6/1 Scr, which is the recommended maximum compression ratio for that cam.
And, Tell me about VE at 3500 @ 8.6Scr... with , .506lift Whiplash-cam, and stock bigport heads no less.
340 ftlbs? Yeah right.
And even if it did, 340 ftlbs sux period, cuz ;
1) that is the same as a stock 1969 318 2bbl was rated at. and
2) And for the amount of money OP is spending.... it really really sux.


But, what do I know;
I'm just a guy that drives 90 minutes to the track, runs a 106 with a 223cam, and drives it back home, at 32mpg, geared for 65=1600; she was my DD. And, with the next bigger cam, she ripped off a 93 in the Eighth.
So you know, Willrun gets the glory, and I get the chitstains. I should be used to it by now.

Op
good luck, I stand by what I said.
"What I do know" Now there's a statement. You know why you get "chitstains"? I'll tell you.
Because people like @318willrun, @junkyardhero me and MANY others post actual PROOF of what they have, what they're working on and the things they have experience with. You post nothing. No pictures, no time slips, nothing. AND on top of THAT, you spew blatant LIES that anyone with half a brain can see right through. All you do is spout information from books, calculators, slide rules and just slap made up outta your mind. You believe the Earth is flat, so there's your sign right there. We watched the space rescue splashdown today and in MANY of the shots, you can CLEARLY see the Earth's curvature at the horizon. You're a blowhard LAIR who literally preys on those who don't know any better and they swallow your BULLCRAP hook, line and sinker. Then when people call you out, you call their faith and Christianity into question. Clearly, you're mentally ill and your position is so weak that you cannot even defend yourself with CURRENT PROOF of ANY Mopar that you own. You fulla CRAP!
 
The DCR calculation makes the assumption from the IVC number that a certain weight [ not volume ] of air has entered the cyl. It does not take into account how well the int port flows & therefore what weight of air actually entered the cyl. It is reasonably useless.
 
careful, he's gonna say you're unchristian for calling him to the floor for what he's said.

but you called it. haters gonna hate. zero proof. everything viewed thru a "performance first" or "acceleration in the 1/8th or whatever" lens.
I think his thing is max acceleration from light to speed limit, he don't let her wind out, why he cares so much about below 3,000 rpms.
the inability to understand that sometimes "decent" is good enough, not everything has to be perfect.
100% a lot people have no choice but to make some vary compromised decision that's good enough or at least good enough for now or just good enough for them.
 
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No, we don’t agree. They are two distinct, different things and you are using the terms like they are interchangeable.

They are not.

But let’s play a game. I’ll use my numbers.

My SCR is 12.2:1.
My ECR is 9.5:1.
My IVC is 71 degrees.

Pump gas.

Calculate my DCR at 1000rpm, 3000 rpm, 5000 rpm and 6500 rpm.

That’s idle, in town cruise rpm, peak torque and shift rpm.

Show me my DCR.

TIA
you are being deliberately obtuse, you spoil, ruin, the validity of the good things and decent advice you give by being awkward and deliberately taking things the wrong way, which is a shame. I'm not trying to compete, i'm just offering up a simple alternative

how may times do i have to say Its a static value based on simple measurement and detail from the cam card, that can help you make a decision regarding your cam choice.
the DCR at 1000 3000 5000 and 6500 is the same. you calculate it once , it provides a basic indication of success or failure. In the same way you just check that your inlet valve doesn't hit your piston and you CC you head or you might CC your ports, its another little tool in the box that lets you know you are on the right track... its a rule of thumb its the plastigage, its helpful when you need it


bewy bit harsh :) but yes in isolation. pretty useless, and you wouldn't use it in a well equipped engine design shop...formula one guys are not talking DCR over lunch... but for simplicity's sake and with other info in hand can be of value.

very much a step up from saying Oh that engines got a CR of 13:1 can't drive that on the street, gonna need race gas . it'll ping like hell on pump gas. Without knowing anything about the cam, but plenty do.
On the other hand i do not have a flow bench do not have a dyno do not have the kit to work out the depression seen in the bowl area of the port when the piston is 3/4 of the way down and i don't have thermocouples embedded in the head. Willing to bet the OP doesn't have a dyno doesn't have a flow bench blaa blaa blaa..


offer up the idea of a simple tool that can help and everyone gets hung up on its slightly misleading name.
When some of you get so spun outta shape on something so basic it really does damage the validity of anything else you say

Dave
 
Static Vs Dynamic Compression Ratio | Piston Ratio

on a site called "engine basics" the clue is in the name....

10 min read
make your own mind up rather than following the rant, if i didn't think there was some merit in it for the OP i wouldn't have bothered, caveats and limitations discussed in last few paragraphs.

stick the maths in excel or google sheets or use someone else's online tool

Dave

here is a guess at the OPs config no idea if the advanced by 5* is ground in or you need to apply it via the keyways on install, yes i took some liberties with the data, not my motor so if i didn't know it i guessed, this tool give me no clue as to what they are doing in the background id probably do it again in another to compare
somewhere in the 8.4 to 8.8 range..

318 with hughes cam.JPG
 
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you are being deliberately obtuse, you spoil, ruin, the validity of the good things and decent advice you give by being awkward and deliberately taking things the wrong way, which is a shame. I'm not trying to compete, i'm just offering up a simple alternative

how may times do i have to say Its a static value based on simple measurement and detail from the cam card, that can help you make a decision regarding your cam choice.
the DCR at 1000 3000 5000 and 6500 is the same. you calculate it once , it provides a basic indication of success or failure. In the same way you just check that your inlet valve doesn't hit your piston and you CC you head or you might CC your ports, its another little tool in the box that lets you know you are on the right track... its a rule of thumb its the plastigage, its helpful when you need it


bewy bit harsh :) but yes in isolation. pretty useless, and you wouldn't use it in a well equipped engine design shop...formula one guys are not talking DCR over lunch... but for simplicity's sake and with other info in hand can be of value.

very much a step up from saying Oh that engines got a CR of 13:1 can't drive that on the street, gonna need race gas . it'll ping like hell on pump gas. Without knowing anything about the cam, but plenty do.
On the other hand i do not have a flow bench do not have a dyno do not have the kit to work out the depression seen in the bowl area of the port when the piston is 3/4 of the way down and i don't have thermocouples embedded in the head. Willing to bet the OP doesn't have a dyno doesn't have a flow bench blaa blaa blaa..


offer up the idea of a simple tool that can help and everyone gets hung up on its slightly misleading name.
When some of you get so spun outta shape on something so basic it really does damage the validity of anything else you say

Dave
you are being deliberately obtuse, you spoil, ruin, the validity of the good things and decent advice you give by being awkward and deliberately taking things the wrong way, which is a shame. I'm not trying to compete, i'm just offering up a simple alternative

how may times do i have to say Its a static value based on simple measurement and detail from the cam card, that can help you make a decision regarding your cam choice.
the DCR at 1000 3000 5000 and 6500 is the same. you calculate it once , it provides a basic indication of success or failure. In the same way you just check that your inlet valve doesn't hit your piston and you CC you head or you might CC your ports, its another little tool in the box that lets you know you are on the right track... its a rule of thumb its the plastigage, its helpful when you need it


bewy bit harsh :) but yes in isolation. pretty useless, and you wouldn't use it in a well equipped engine design shop...formula one guys are not talking DCR over lunch... but for simplicity's sake and with other info in hand can be of value.

very much a step up from saying Oh that engines got a CR of 13:1 can't drive that on the street, gonna need race gas . it'll ping like hell on pump gas. Without knowing anything about the cam, but plenty do.
On the other hand i do not have a flow bench do not have a dyno do not have the kit to work out the depression seen in the bowl area of the port when the piston is 3/4 of the way down and i don't have thermocouples embedded in the head. Willing to bet the OP doesn't have a dyno doesn't have a flow bench blaa blaa blaa..


offer up the idea of a simple tool that can help and everyone gets hung up on its slightly misleading name.
When some of you get so spun outta shape on something so basic it really does damage the validity of anything else you say

Dave
IMG_0993.jpeg
 
you are being deliberately obtuse, you spoil, ruin, the validity of the good things and decent advice you give by being awkward and deliberately taking things the wrong way, which is a shame. I'm not trying to compete, i'm just offering up a simple alternative

how may times do i have to say Its a static value based on simple measurement and detail from the cam card, that can help you make a decision regarding your cam choice.
the DCR at 1000 3000 5000 and 6500 is the same. you calculate it once , it provides a basic indication of success or failure. In the same way you just check that your inlet valve doesn't hit your piston and you CC you head or you might CC your ports, its another little tool in the box that lets you know you are on the right track... its a rule of thumb its the plastigage, its helpful when you need it


bewy bit harsh :) but yes in isolation. pretty useless, and you wouldn't use it in a well equipped engine design shop...formula one guys are not talking DCR over lunch... but for simplicity's sake and with other info in hand can be of value.

very much a step up from saying Oh that engines got a CR of 13:1 can't drive that on the street, gonna need race gas . it'll ping like hell on pump gas. Without knowing anything about the cam, but plenty do.
On the other hand i do not have a flow bench do not have a dyno do not have the kit to work out the depression seen in the bowl area of the port when the piston is 3/4 of the way down and i don't have thermocouples embedded in the head. Willing to bet the OP doesn't have a dyno doesn't have a flow bench blaa blaa blaa..


offer up the idea of a simple tool that can help and everyone gets hung up on its slightly misleading name.
When some of you get so spun outta shape on something so basic it really does damage the validity of anything else you say

Dave
dy·nam·ic
/dīˈnamik/

adjective

  1. 1.
    (of a process or system) characterized by constant change, activity, or progress.
    "a dynamic economy"










  • 2.
    (of a person) positive in attitude and full of energy and new ideas.
    "she's dynamic and determined"

    effective​

    1 of 2

    adjective

    ef·fec·tive i-ˈfek-tiv
    e-,

    ē-,

    ə-

    Synonyms of effective
    1
    a
    : producing a decided, decisive, or desired effect
    an effective policy

    b
    : impressive, striking
    a gold lamé fabric studded with effective … precious stones—Stanley Marcus


    I know that "dynamic" sounds cool and smart and educated but it's wrong.
    Just like Static Compression Ratio, Effective Compression ratio is STATIC. But you can calculate it and you can quantify it.
    Let's do my junk because I have the exact numbers. BTW, this isn't for you. You're over the hill and far away on this and I doubt anyone can bring you back. This is for the guys who want to continue to learn and then apply what they learn to make their junk better.


    Obtuse?? Hardly. I'm trying to explain to you that by DEFINITION you are wrong. And you quadruple down on the wrong

    You are refusing to see how you are steering people in the wrong direction. Shame on John Wallace for even using the term for his calculators.

    That's why you didn't calculate my "dynamic" compression ratio because you can't. Yet you continue to claim its real and valuable. It's not.

    The effective compression ratio is what the engine sees while running. While the static CR is defined simply by the geometry of the engine, the effective CR is influenced by multiple factors such as the engine geometry, cam timing, intake pressure, connecting rod length, and volumetric efficiency.

    It is the effective CR that determines how much the fluid is actually compressed during engine operating and therefore the minimum octane rating necessary to avoid pre-detonation. This is why some engines require 100+ octane with an 11:1 compression ratio while others are perfectly fine on 91 octane with a 13:1 compression ratio. E-85 has an equivalent octane rating of 105, and with an expected operating temperature of around 180°F, the maximum dynamic CR is slightly above 10.5

    To get higher VE% from high performance engines, the camshaft intake valve is usually closed significantly after BDC compared to a 'street' type of engine. This later closing intake point helps contribute to additional cylinder filling using 'ramming' properties of the intake flow.

    This later closing point reduces the engine's 'effective compression ratio' to below the static compression ratio.

    Basically the piston is traveling up from BDC on the compression stroke when the intake valve is still open. This is effectively bleeding off the compression pressure, while still filling the chamber with fresher air/fuel mixture. (better VE%)

    It is basically using a percentage of the compression stroke before it starts compressing the fuel/air mixture!

    This 'effective compression ratio' can be lower than the popular 'Dynamic Compression Ratio' however. (or even higher depending on cam data)

    It calculates all the effects of the cylinder intake pumping and ramming processes with the trapped air/fuel at the intake closing point.

    Effective Compression Ratio is 9.48

    Dynamic Compression Ratio is 9.56

    Boost Compression Ratio is 9.36

    Piston travel percent is 23.58 %
    (of the stroke)

    Piston Travel is 0.78 inches up from BDC
    At Intake Closing - 65.5 Degrees

    Per Wallace, my numbers are: 6.123 rod length, 65.5 IVC, 3.313 stroke, 12.2 SCR, 0 boost, 1k feet elevation and 108% VE.

    Notice how close ECR and DCR are. Look at it. Wallace uses elevation and VE as part of the equation.

    Let's use Wallace for DCR just for the maths.​

    Use this calculator to see what the effect of bore, stroke, rod length, cam timing, compression ratio, boost pressure and altitude is on your dynamic compression ratio. Of the variables, the most important is cam timing which has a dramatic effect on your "dynamic" as opposed to your static compression ratio. The more "overlap" your cam has, the lower your "actual" as opposed to your static compression ratio will be. This is one area you can easily change.​
    Another consideration is rod length and it's effect on the engine's output. Changing the rod length will affect the piston location in the bore relative to cam timing everywhere except at TDC and BDC thus changing the dynamics of the engine. Ooooooopsie, they are the F'ing SAME.
    Dynamic Compression Ratio Calculator
    Number of Cylinders :
    8
    Bore in Inches :
    4.04
    Stroke in Inches :
    3.313
    Rod Length in Inches :
    6.123
    Static Compression Ratio :
    (:1) 12.2
    Inlet Valve Closes ABDC :
    ° 65.5
    Boost Pressure in PSI :
    0
    Target Altitude :
    (Feet) 1000

    Camshaft, Rod Length, Boost and Altitude Correction to Compression​

    Static compression ratio of 12.2:1.
    Effective stroke is 2.53 inches.
    Your dynamic compression ratio is 9.55:1 .
    Your dynamic cranking pressure is 200.23
    PSI.
    Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0
    PSI is 9.35 :1.
    V/P (Volume to Pressure Index) is 156



    Use this calculator to see what the effect of bore, stroke, rod length, cam timing, compression ratio, boost pressure and altitude is on your dynamic compression ratio. Of the variables, the most important is cam timing which has a dramatic effect on your "dynamic" as opposed to your static compression ratio. The more "overlap" your cam has, the lower your "actual" as opposed to your static compression ratio will be. This is one area you can easily change.​
    Another consideration is rod length and it's effect on the engine's output. Changing the rod length will affect the piston location in the bore relative to cam timing everywhere except at TDC and BDC thus changing the dynamics of the engine.

    Look Dave, It's the same exact numbers in the formula, with the exception that ECR accounts for VE and DCR does not. That's a HUGE issue Dave. MASSIVE issue. I posted the definition of dynamic and effective and they are not the same. Dynamic means (and you KNOW this Dave because you are NOT a stupid man) changing with environmental or external forces, while effective means the end result. One can and must change and the other does not. We can't have it both ways Dave. Why Wallace has the dynamic calculator is beyond me because all it does is screw guys up.​

    I apologize for the bold text. Once I did copy and paste from Wallace it changed to bold and I'm not messing with it.


  • I don't know what else to say. Even Wallace can't get it straight. But what BOTH of those calculators calculate is EFFECTIVE COMPRESSION RATIO. It's just that the only correct answer is both are calculating ECR and the ECR calculator is correct while the DCR is not because it ignores VE. And let's be clear, what he calls DCR is actually the correct math for ECR!!! Why? Because it uses VE in the equation. For the calculation to be "dynamic" you MUST include RPM, load, IAT, fuel and some other **** I don't remember.​

  • So how about we stop the madness today Dave? Why keep using incorrect terminology and continue to jack up the true definitions we use?​

    The upshot is ECR is useful because we are EFFECTIVELY shortening the stroke length by using IVC to calculate the "running" compression ratio. Because the actual stroke length never changes and the IVC never changes (assuming a rigid valve train without camshaft torsional loses, pushrod and rocker flex and the like. That's why its NOT dynamic. Neither is the Wallace or ANY OTHER CALCULATOR giving you DYNAMIC compression ratio because that alone assumes a changing environment and there's nothing in the math that even supposes dynamic anything.
    I suggest you stop being obtuse and crapping in the kitchen Dave.



  •  
    Got a 318 40 over flattop pistons bought a set of howards valve set from summit I ordered a hughes hugsmc2336Al 340 360 107 lsa +5 cam just want to add my hughes cam came with howards cam papers telling how ti break in two in total howards cams wondered if anybody has had the same experience but back to it the moter cane with 714 heads on it nice quench pad but but valve restricts the flow I've seen several video of handporting and seen gains my question is which heads should I use on the 49 over 318 gonna put it in a 91 dalota 5 speed 373 gear going to be a toy not at all concerned about economy I watch charles sevidio on the 714 heads and watched David vizard and Charles sevidio port the 360 j heads I have a air gap intake with 360 ports I know with the 360 heads u lose compression but think the intake and head port matched would add power and the atomizariob of the gas instead of it puddling on a ledge I need some pointers as to if I use the head of yalls choice which gasket should I use what would he a good part tgat would kero my distributor from advancing to much etc just need a Game plan from someone who is familiar with the moter parts etc in my mind the j heads are the choice and if I do use them is there a dome piston that would help me achieve power specifics with j style head hughes seems particular on the valve springs would the howards springs be a good enough set I just need a run down on what would be the best advice for a combo with what I got
    By the time you deshroud the 714/302 heads they are no longer 64 cc's, more like 68 or 69cc
    There's no magic in any those people doing what they do, and flow benches very. Many of them are only doing it for expanding their audience....hence they never fkd with mopar **** before that, and there's so many vids that they could use all of that free info to chart a course and exploit it for all its worth.
     
    Guess I could giveit another shot got a 40 over 318 and I got the 340 / 360 whiplash cam got 714 heads and 360 j heads trying to get advice on which heads to run on the moter my intake ports are matched fir a 360 hope this is better


    Mill .040 from the j heads and use those with a good valve job.
     
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