318 build

[junkyard kid]

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

 

[junkyard kid]

I apologize I'm new to trying to text so much information kinda got it All mixed up but the moter info can etc is specified it may not be perfect but pretty sure if your on thus site your start enough to put the pieces together i will do better in the future

 

[junkyard kid]

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

 

[Professor Fate]

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

Run both sets of numbers through a compression calculator- you'll need to know the compression height of whatever brand and model pistons you have, the combustion chamber volume of both sets of heads, and the compressed thickness of your head gasket.
Compression Calculator
If you can juggle the parts around (thinner gaskets, shave the heads, etc.) to get 9.5:1 or better with the J heads, I'd use those.
If the 318 heads give you a better CR, and the ports are matched to the 360 size (which I think is what you are saying), then go with those.
The Whiplash cam will be okay with either set of heads, but a bit better with the Js if the compression works out.

 

[Garrett Ellison]

in my mind the j heads are the choice and if I do use them is there a dome piston

With J heads on a 318, it's best to to have the block decks cut to make the piston crowns go to zero or above deck. Usually 318 pistons are .060 below deck or more. But dome pistons are definitely good for a 9.5:1 or better engine. The 1.81 compression height of the domes will give you a .012 below deck with the block trued to 9.6 inch deck height.
Which Howard's valve springs (P/N) do you have?
PLYMOUTH 5.2L/318 Mopar small block LA Pistons Pistons & Piston Rings Engines & Components - 3.950 in. Bore (in.) - Dome, with two valve reliefs Piston Style - Free Shipping on Orders Over $109 at Summit Racing
Use Felpro 1008 head gaskets
PLYMOUTH Fel-Pro 1008 Fel-Pro Performance Head Gaskets | Summit Racing

 

[273]

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

I'd probably go with 360 heads, you can mill some off to make the chambers smaller.

You say flat top pistons, generally replacement ones or ones for zero deck ?

 

[junkyard kid]

With J heads on a 318, it's best to to have the block decks cut to make the piston crowns go to zero or above deck. Usually 318 pistons are .060 below deck or more. But dome pistons are definitely good for a 9.5:1 or better engine. The 1.81 compression height of the domes will give you a .012 below deck with the block trued to 9.6 inch deck height.
Which Howard's valve springs (P/N) do you have?
PLYMOUTH 5.2L/318 Mopar small block LA Pistons Pistons & Piston Rings Engines & Components - 3.950 in. Bore (in.) - Dome, with two valve reliefs Piston Style - Free Shipping on Orders Over $109 at Summit Racing
Use Felpro 1008 head gaskets
PLYMOUTH Fel-Pro 1008 Fel-Pro Performance Head Gaskets | Summit Racing

 

[junkyard kid]

The ones from summit there 61 bucks without nothing bit the springs 131 complete kit watch David vizard alot he claimed they was as good as a spring twice as high pr8ced springs seat pressures 150 lbs

 

[junkyard kid]

Run both sets of numbers through a compression calculator- you'll need to know the compression height of whatever brand and model pistons you have, the combustion chamber volume of both sets of heads, and the compressed thickness of your head gasket.
Compression Calculator
If you can juggle the parts around (thinner gaskets, shave the heads, etc.) to get 9.5:1 or better with the J heads, I'd use those.
If the 318 heads give you a better CR, and the ports are matched to the 360 size (which I think is what you are saying), then go with those.
The Whiplash cam will be okay with either set of heads, but a bit better with the Js if the compression works out.

 

[junkyard kid]

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

 

[AJ/FormS]

Is that 5-speed the AX-15, or the NV3500 or something else?

That Whiplash cam is gonna have advertised specs of around 270/284/107. which means, in at 105, the Ica is gonna be 60* and the overlap comes to 63*, which is between two and 3 times as much as a regular 223/236 cam would have. This is what gives it that lumpy idle.
The thing is, if you are willing to put up with that idle, then why not run a "real cam" of about the same advertised intake, say a 268/276/108; which could be 226/232, @050, and pick up a lil extra absolute power, and extra power stroke, while sacrificing one cam-size worth of overlap, which, on the street in two gears, doesn't count for much anyway.
That lil 223 whiplash is gonna power-peak around 5000, maybe up to 5200. So with the Ax15, you'll probably pull the 1-2 shift around 5700, to get into Second at 3500, and, with 3.73s and say 29" tires, this is gonna be 34mph. The 2-3 split in that trans is also a wide ratio, so Second will also need to go to about 5700, now at 57mph. Stuffing it into Third, yur back to 3500, and your street-race is over, unless you are willing to risk getting a speeding ticket. Third will get you 83mph@5200, but pulling from 3500, that's a really long leg, especially for a 318........ so it better have compression.
To get it, I recommend alloy heads, and run the pressure up to more than 185 psi; perhaps as high as 200. I suppose that now you could run that Whiplash to bleed the pressure down at low rpm.
Your starter gear of 3.83 x 3.73=14.30, with 29s (which would act like 12.62 with 26s), is gonna be right on. But
I still wouldn't run that Whiplash.
-----------------------
BTW-1
Just so you know, a long time ago, in my 367LA, I ran a Hughes fast-rate 223/230/110 cam, which was 270/276@050, with alloy heads at up to 195psi. I initially ran it with a Mopar od box and a GVod behind it, for gear-splitting. In double overdrive the cruize rpm was; 65=1600/ 85=2100 rpm, I coaxed 32 mpg out of that combo.
The point is; pressure makes heat, and heat makes torque, and torque times rpm makes power. I ran that pressure on cheap 87E10 gas.
With your iron head combo, 9.8 Scr will be pushing it with 91 gas, and the bottom-end will still feel like a 318, because of the late-closing intake event, coupled with the long-period overlap.
IMO, if you're gonna sacrifice the bottom end like that, then you might as well run a "real cam" in the first place. or Pump up the pressure to use Alloy heads.
Just so you know;
That 223/230/110 cam was my favorite of the three cams that my 367 has entertained. IMO, Hughes knocked it out of the park with that one; and at 11.3 Scr, I just made it that much better.
BTW-2
IMO, 3.73s are the wrong rear gear for your combo for your stated usage with tall tires. IMO, for low-ET, you really want to hit 65mph on the power peak, in either Second or Third gear.
Also, in that AX-15, the first two splits are VERY wide, 61% and 62%. They do not play well with a high-rpm engine. For a shift rpm of 5700, the rpm drop is to 3500, which means your engine needs a powerband of 2200. You'll never get that out of your iron-headed 318 at 160/165 psi. It will be ok on the 1-2, cuz she's blasting to 34 mph with tires on fire. But when she shifts to Second, or especially Third, that's when you're gonna feel it. The 3>4 split is 69%, so when you get there, you'll be back in action, but with 3.73s your speed is gonna be, out of sight.
That trans is a dream for a hi-torque 3.9/5.2, with the long-ram intake, like the factory "keg".
BTW-3
The NV 3500 has better splits, but still no hell, and from what I remember, it's quite heavy, being for a truck.
Since you don't care about hi-way economy, I recommend the Commando 4-speed. It still has a wide 1-2 split, but the 2>3 is better, and the 2>3 is really good ....... with the right rear gear. I've been running it since about 2004 and am real happy.
BTW-4
Here is a gear-ratio breakdown;
AX-15; 3.83-2.33-1.44-1.00-.79od; splits of .61/.62/.69/.79
A833; 3.09-1.92-1.40-1.00; splits of .62/.73/.715
This only tells part of the story; to see the rest, you need to include the rear gear, in your case 3.73s. You can see this by converting each gear to an On-Road gear by multiplying the two. Thus the Roadgears with 3.73s, become;
AX15; 14.29-8.68-5.37-3.73-2.95 and
Mopar; 11.53-7.16-5.22-3.73 and to hit 5700 @65mph with 29"tires, you need a gear of 7.56.
To keep the AX, you need;
7.56/2.33=3.24s for Second or 7.56/1.44=5.25s for Third.
To use the Commando, you need
7.56/1.92= 3.94s for Second or 7.56/1.40= 5.40 for Third.
It is highly unlikely that you would run 5.xxs on the street. Therefore, your choices are; 3.24s for the AX, or 3.94s for the Commando. Your starter gears then, would be;
12.41 for the AX, and 12.08 for the Commando
The payoff is in the 2>3 split, where the AX drops to 3500 from 5700, whereas the Mopar only falls to 4160, putting you 660 rpm further up the Powerband, and now pulling harder, especially with a "real cam", lol.
I say "real cam", in jest.
The Whiplash has it's place in the HotRod world. I mean, it sounds pretty nasty at idle.
But
nobody races at idle.
And once you wind it up, it's "just" a 223 cam.
If yur ok with that, who cares what my opinion is.
BTW-5
I eventually swapped that Hughes 223/230/110 out, for a 230/237/110, also from Hughes..
That gave me about the same overlap as your whiplash has, but changed the Ica to 66 from 60, dropping my cylinder pressure. To get it back, I just decked the block again. So,
my "real cam" now idles like your Whiplash.
But whereas the car went 106mph in the qtr with the 223 cam, it now goes 93 in the Eighth with the 230 cam.
That's a hell uvathing. Everything else is the same. Well not quite, the small cam was at 3650 pounds, while, the larger cam was at 3457, a difference of 193 pounds, which itself was worth 19hp. The rest was in the cam, and it's combo.
The Wallace calculator says it takes 335hp to go 106(Qtr), and 433 to go 93(1/8th). So, to say I was ecstatic, would not be overstating it. But
I wouldn't want any more cam than this, in my manual-trans combo. BTW, my alloy heads are OOTB Eddies.
BTW-6
going back to topping out at 34mph =5700 in First/3500 in Second, I can tell you that this really sux.
Say you are cruizing along at 34mph in third gear, just minding you own business. For whatever reason, you get the urge to have at it. You can't go to first, cuz it's all used up. Your only choice is Second. But when you downshift, the lil 318 is stuck at 3500 rpm with maybe 160psi pressure. Fogedabowd it. Yet this is just about exactly what is gonna happen to you over and over and over, with that AX15 and 3.73s.

In any case
Happy HotRodding

 

[Newbomb Turk]

Is that 5-speed the AX-15, or the NV3500 or something else?

That Whiplash cam is gonna have advertised specs of around 270/284/107. which means, in at 105, the Ica is gonna be 60* and the overlap comes to 63*, which is between two and 3 times as much as a regular 223/236 cam would have. This is what gives it that lumpy idle.
The thing is, if you are willing to put up with that idle, then why not run a real cam of about the same advertised intake, say a 268/276/108; which could be 226/232, @050, and pick up a lil extra absolute power, and extra power stroke, while sacrificing one cam-size worth of overlap, which, on the street in two gears, doesn't count for much anyway.
That lil 223 whiplash is gonna power-peak around 5000, maybe up to 5200. So with the Ax15, you'll probably pull the 1-2 shift around 5700, to get into Second at 3500, but with 3.73s and say 29" tires, this is gonna be 34mph. The 2-3 split in that trans is also a wide ratio, so Second will also need to go to about 5700, now at 57mph. Stuffing it into Third, yur back to 3500, and your streetrace is over, unless you are willing to risk getting a speeding ticket. Third will get you 83mph@5200, but pulling from 3500, that's a really long leg, especially for a 318........ so it better have compression.

To get it, I recommend alloy heads, and run the CCP pressure up to more than 185 psi; perhaps as high as 200. Now you can run that Whiplash to bleed the pressure down at low rpm. And your starter gear of 3.83 x 3.73=14.30, with 29s (which would act like 12.62 with 26s), is gonna be right on.
I still wouldn't run that Whiplash.
Just so you know, a long time ago, ij my 367LA, I ran a Hughes fast-rate 223/230/110 cam, which was 270/276@050 with alloy heads at up to 195psi. I ran it with a Mopar od box and a GVod behind it. In double overdrive the cruize rpm was; 65=1600/ 85=2100 rpm, I coaxed 32 mpg out of that combo.
The point is; pressure makes heat, and heat makes torque, and torque times rpm makes power. I ran the pressure on cheap 87E10 gas.
With your iron head combo, 9.8 Scr will be pushing it with 91 gas, and the bottom-end will still feel like a 318, because of the late-closing intake event, coupled with the long-period overlap.
IMO, if you're gonna sacrifice the bottom end like that, then you might as well run a bigger cam in the first place. or Pump up the pressure to use Alloy heads.
-------------------------------------------------
BTW
That 223/230/110 cam was my favorite of the three cams that my 367 has entertained. IMO Hughes knocked it out of the park with that one; and at 11.3 Scr, I just made it that much better.

BTW-2
IMO, 3.73s are the wrong rear gear for your combo for your stated usage with tall tires. IMO, for low-ET, you really want to hit 65mph on the power peak, in either Second or Third gear.
Also, in that AX-15, the first two splits are VERY wide, 61% and 62%. They do not play well with a high-rpm engine. For a shift rpm of 5700, the rpm drop is to 3500, which means your engine needs a powerband of 2200. You'll never get that out of your iron-headed 318 at 160/165 psi. It will be ok on the 1-2, cuz she's blasting to 34 mph with tires on fire. But when she shifts to Second, or especially Third, that's when you're gonna feel it. The 3>4 split is 69%, so now yur back in action, but with 3.73s your speed is out of sight.
That trans is a dream for a hi-torque 5.2, with the long-ram intake, sorta like the factory "keg".

BTW-3
The NV 3500 has better splits, but still no hell.
Since you don't care about hi-way economy, I recommend the Commando 4-speed. It still has a wide 1-2 split, but the 2>3 is better, and the 2>3 is really good ....... with the right rear gear. I've been running it since about 2004 and am real happy.
BTW-4
Here is a gear-ratio breakdown;
AX-15; 3.83-2.33-1.44-1.00-.79od; splits of .61/.62/.69/.79
A833; 3.09-1.92-1.40-1.00; splits of .62/.73/.715

This only tells part of the story; to see the rest, you need to include the rear gear, in your case 3.73s. Yo can see this by converting each gear to an On-Road gear by multiplying the two. Thus the Roadgears become
AX15; 14.29-8.68-5.37-3.73-2.95 and
Mopar; 11.53-7.16-5.22-3.73 and to hit 5700 @65mph with 29"tires, you need a gear of 7.56.
To keep the AX, you need;
7.56/233=3.24s for Second or 7.56/1.44=5.25s for Third.
To use the Commando, you need
7.56/1.92= 3.94s for Second or 7.56/1.40= 5.40 for Third

It is highly unlikely that you would run 5.40s on the street. Therefore, your choices are; 3.24s for the AX, or 3.94s for the Commando. Your starter gears then, would be
12.41 for the AX, and 12.08 for the Commando
The payoff is in the 2>3 split, where the AX drops to 3500 from 5700, whereas the Mopar only falls to 4160, putting you 660 rpm further up the Powerband, and now pulling harder, especially with a real cam, lol.
I say "real cam", in jest. The Whiplash has it's place in the HotRod world. I mean, it sounds pretty good at idle.
But
nobody races at idle.
And once you wind it up, it's "just" a 223 cam.
If yur ok with that, who cares what my opinion is.
BTW-5
I eventually swapped that 223/230/110 out, for a 230/237/110..
That gave me about the same overlap as your whiplash, but changed the Ica to 66 from 60, dropping my cylinder pressure. To get it back, I just decked the block again. So,
my "real cam" now idles like your Whiplash.
But whereas the car went 106mph in the qtr with the 223 Hughes cam, it now goes 93 in the Eighth with the 230 cam.
That's a hell uvathing. Everything else is the same. Well not quite, the small cam was at 3650 pounds, while, the larger cam was at 3457, a difference of 193 pounds, which itself was worth 19hp. The rest was in the cam, and it's combo.
The Wallace calculator says it takes 335hp to go 106(Qtr), and 433 to go 93(1/8th). So, to say I was ecstatic, would not be overstating it. But
I wouldn't want any more cam than this in my manual-trans combo. BTW, my alloy heads are OOTB Eddies.
In any case
Happy HotRodding

Because the OP doesn’t have the compression to run those cams.

Next thing you, he’ll be on here trying to figure out why he can’t get it to idle and he will need to run manifold vaccum advance with 45-50 degrees of timing at idle.

Then he won’t be able to get the curve correct and it will drone like ****.

This whiplash and thumper cams work very well with low compression.

That’s what he should use and it should be the SMALLEST in that line. If he bought one that isn’t the smallest he needs to send it back and get the small one.

 

[Newbomb Turk]

Is that 5-speed the AX-15, or the NV3500 or something else?

That Whiplash cam is gonna have advertised specs of around 270/284/107. which means, in at 105, the Ica is gonna be 60* and the overlap comes to 63*, which is between two and 3 times as much as a regular 223/236 cam would have. This is what gives it that lumpy idle.
The thing is, if you are willing to put up with that idle, then why not run a "real cam" of about the same advertised intake, say a 268/276/108; which could be 226/232, @050, and pick up a lil extra absolute power, and extra power stroke, while sacrificing one cam-size worth of overlap, which, on the street in two gears, doesn't count for much anyway.
That lil 223 whiplash is gonna power-peak around 5000, maybe up to 5200. So with the Ax15, you'll probably pull the 1-2 shift around 5700, to get into Second at 3500, but with 3.73s and say 29" tires, this is gonna be 34mph. The 2-3 split in that trans is also a wide ratio, so Second will also need to go to about 5700, now at 57mph. Stuffing it into Third, yur back to 3500, and your street-race is over, unless you are willing to risk getting a speeding ticket. Third will get you 83mph@5200, but pulling from 3500, that's a really long leg, especially for a 318........ so it better have compression.

To get it, I recommend alloy heads, and run the pressure up to more than 185 psi; perhaps as high as 200. Now you can run that Whiplash to bleed the pressure down at low rpm. And your starter gear of 3.83 x 3.73=14.30, with 29s (which would act like 12.62 with 26s), is gonna be right on.
I still wouldn't run that Whiplash.

BTW-1
Just so you know, a long time ago, in my 367LA, I ran a Hughes fast-rate 223/230/110 cam, which was 270/276@050, with alloy heads at up to 195psi. I ran it with a Mopar od box and a GVod behind it. In double overdrive the cruize rpm was; 65=1600/ 85=2100 rpm, I coaxed 32 mpg out of that combo.
The point is; pressure makes heat, and heat makes torque, and torque times rpm makes power. I ran the pressure on cheap 87E10 gas.
With your iron head combo, 9.8 Scr will be pushing it with 91 gas, and the bottom-end will still feel like a 318, because of the late-closing intake event, coupled with the long-period overlap.
IMO, if you're gonna sacrifice the bottom end like that, then you might as well run a "real cam" in the first place. or Pump up the pressure to use Alloy heads.
Just so you know;
That 223/230/110 cam was my favorite of the three cams that my 367 has entertained. IMO Hughes knocked it out of the park with that one; and at 11.3 Scr, I just made it that much better.

BTW-2
IMO, 3.73s are the wrong rear gear for your combo for your stated usage with tall tires. IMO, for low-ET, you really want to hit 65mph on the power peak, in either Second or Third gear.
Also, in that AX-15, the first two splits are VERY wide, 61% and 62%. They do not play well with a high-rpm engine. For a shift rpm of 5700, the rpm drop is to 3500, which means your engine needs a powerband of 2200. You'll never get that out of your iron-headed 318 at 160/165 psi. It will be ok on the 1-2, cuz she's blasting to 34 mph with tires on fire. But when she shifts to Second, or especially Third, that's when you're gonna feel it. The 3>4 split is 69%, so now yur back in action, but with 3.73s your speed is out of sight.
That trans is a dream for a hi-torque 5.2, with the long-ram intake, sorta like the factory "keg".

BTW-3
The NV 3500 has better splits, but still no hell.
Since you don't care about hi-way economy, I recommend the Commando 4-speed. It still has a wide 1-2 split, but the 2>3 is better, and the 2>3 is really good ....... with the right rear gear. I've been running it since about 2004 and am real happy.
BTW-4
Here is a gear-ratio breakdown;
AX-15; 3.83-2.33-1.44-1.00-.79od; splits of .61/.62/.69/.79
A833; 3.09-1.92-1.40-1.00; splits of .62/.73/.715

This only tells part of the story; to see the rest, you need to include the rear gear, in your case 3.73s. Yo can see this by converting each gear to an On-Road gear by multiplying the two. Thus the Roadgears become
AX15; 14.29-8.68-5.37-3.73-2.95 and
Mopar; 11.53-7.16-5.22-3.73 and to hit 5700 @65mph with 29"tires, you need a gear of 7.56.
To keep the AX, you need;
7.56/233=3.24s for Second or 7.56/1.44=5.25s for Third.
To use the Commando, you need
7.56/1.92= 3.94s for Second or 7.56/1.40= 5.40 for Third

It is highly unlikely that you would run 5.40s on the street. Therefore, your choices are; 3.24s for the AX, or 3.94s for the Commando. Your starter gears then, would be
12.41 for the AX, and 12.08 for the Commando
The payoff is in the 2>3 split, where the AX drops to 3500 from 5700, whereas the Mopar only falls to 4160, putting you 660 rpm further up the Powerband, and now pulling harder, especially with a real cam, lol.
I say "real cam", in jest. The Whiplash has it's place in the HotRod world. I mean, it sounds pretty good at idle.
But
nobody races at idle.
And once you wind it up, it's "just" a 223 cam.
If yur ok with that, who cares what my opinion is.
BTW-5
I eventually swapped that 223/230/110 out, for a 230/237/110..
That gave me about the same overlap as your whiplash, but changed the Ica to 66 from 60, dropping my cylinder pressure. To get it back, I just decked the block again. So,
my "real cam" now idles like your Whiplash.
But whereas the car went 106mph in the qtr with the 223 Hughes cam, it now goes 93 in the Eighth with the 230 cam.
That's a hell uvathing. Everything else is the same. Well not quite, the small cam was at 3650 pounds, while, the larger cam was at 3457, a difference of 193 pounds, which itself was worth 19hp. The rest was in the cam, and it's combo.
The Wallace calculator says it takes 335hp to go 106(Qtr), and 433 to go 93(1/8th). So, to say I was ecstatic, would not be overstating it. But
I wouldn't want any more cam than this in my manual-trans combo. BTW, my alloy heads are OOTB Eddies.
In any case
Happy HotRodding

View attachment 1716380033

 

[Danny Bellmore]

[ATT

View attachment 1716380033View attachment 1716380034View attachment 1716380036
View attachment 1716380035

Love this set up. It would look great on my dart.

 

[273]

The point is; pressure makes heat, and heat makes torque, and torque times rpm makes power.

CR is important but not as important as Volumetric Efficiency, a point of cr is only worth like 3% power, on a 300 hp engine is 9 hp.

I ran that pressure on cheap 87E10 gas.
With your iron head combo, 9.8 Scr will be pushing it with 91 gas, and the bottom-end will still feel like a 318, because of the late-closing intake event, coupled with the long-period overlap.

What evidence?

They do not play well with a high-rpm engine. For a shift rpm of 5700, the rpm drop is to 3500, which means your engine needs a powerband of 2200. You'll never get that out of your iron-headed 318 at 160/165 psi.

Again what evidence?

going back to topping out at 34mph =5700 in First/3500 in Second, I can tell you that this really sux.
Say you are cruizing along at 34mph in third gear, just minding you own business. For whatever reason, you get the urge to have at it. You can't go to first, cuz it's all used up. Your only choice is Second. But when you downshift, the lil 318 is stuck at 3500 rpm with maybe 160psi pressure. Fogedabowd it.

So power 3500 ish is gonna be no good, based on what ?

Hp is 66.5% of torque at 3,500 rpms, say it's making around 340 lbs-ft @ 3,500 rpm that's 226 hp, that's not enough power to pull from ?

Peak torque around 4,000 rpm (give or take) is gonna give you the most useful range of power under 5,000 rpms plus let's you pull up to 5,500-6,000 rpms when needed.

 

[Professor Fate]

a point of cr is only worth like 3% power, on a 300 hp engine is 9 hp.

Not to be nitpicky, but that is too broad of a brush to paint with.
A point of CR is going to affect power differently depending on where your starting point is- ie going from 10:1 to 11:1 is going to change power output significantly more than a change from say, 8:1 to 9:1.
It should be treated as a variable, not an absolute.

 

[273]

Not to be nitpicky, but that is too broad of a brush to paint with.
A point of CR is going to affect power differently depending on where your starting point is- ie going from 10:1 to 11:1 is going to change power output significantly more than a change from say, 8:1 to 9:1.
It should be treated as a variable, not an absolute.

You are correct, but I'm not gonna write a book about every possible variable. Point is it's important but not the end of the world, especially compared to VE% which AJ never seems to factor in among other things.

 

[Bewy]

Nope, going from 8 to 9 to 1 CR will have a bigger percentage change than going from 10 to 11 to1....


And, using man vac adv does NOT cause exh drone.....

 

[273]

Nope, going from 8 to 9 to 1 CR will have a bigger percentage change than going from 10 to 11 to1....


And, using man vac adv does NOT cause exh drone.....

View attachment 1716380502

Going from 8:1 to 12:1 is 11.5 % divide by 4 = 2.875 % average, 3% close enough for most.

Point was on a relatively low power engine 250-350 hp a percentage of a point to a point or two ain't gonna make a huge difference in power especially compared to increased VE%.

AJ always going on about CR V/P Cranking pressure as the reason to not do a cam but always leaves out VE% obviously you want both if you can but if you only can increase one is still an increase in power.

 

[volaredon]

I've recently read in several posts how an increase in CR by itself doesn't mean much, both here and other sites I go to. I'm surprised by that. I would have thought it would have had a bigger difference.
And I don't get that V/P thing that AJ is always talking about. Just like I don't get "cam talk" very well either. Just know that I'm gun shy on cams since I bought and installed one many years ago that made alot of noise but really didn't run very well, definitely nowhere near how I was expecting.

 

[Dave999]

exactly the reason why using a DCR calculator to choose a cam to make your motor work as best it can pays dividends
someone else has done the hard work coming up with a formula that seems to be relatively reliable and we can take advantage

Static CR means nothing without relating the piston speed and direction of the piston to the cam timing and LSA.
and they really need to match your bore stroke and rod length in relation to stroke.
Put motor dimensions and cam detail into DCR calculator
look for a DCR of 7.5 -7.9 for a real good performer on premium gas
if it comes out at 8.5 or 9 or 5.5 sell that cam and get the right one for the critical dimensions of you motor.

better ways as always, to do things, but this works for mugs like me....

and you can of course do this the other way around and choose to increase static CR and leave cam alone and see what impact that has on DCR.. couple of thou off head and block to clean it up..... work out the impact....etc

Dave

 

[273]

I've recently read in several posts how an increase in CR by itself doesn't mean much, both here and other sites I go to. I'm surprised by that. I would have thought it would have had a bigger difference.
And I don't get that V/P thing that AJ is always talking about. Just like I don't get "cam talk" very well either. Just know that I'm gun shy on cams since I bought and installed one many years ago that made alot of noise but really didn't run very well, definitely nowhere near how I was expecting.

Here's the site for V/P, problem is you can have a high HP engine with low V/P and vice versa, AJ say's it really effects under 3,000 rpms but yet to show any proof other than his made up scenarios.​

​

​

"V/P Index

A reasonable estimate of the relative effects of compression ratio, rod ratio, and intake valve closing point at cranking speed can be made by use of a simple formula. "​

Cam Timing vs. Compression Analysis

 

[Dave999]

and "compression ratio effective" on that page is DCR, it would appear that i was harping on about much the same thing without realizing it

 

[Newbomb Turk]

I've recently read in several posts how an increase in CR by itself doesn't mean much, both here and other sites I go to. I'm surprised by that. I would have thought it would have had a bigger difference.
And I don't get that V/P thing that AJ is always talking about. Just like I don't get "cam talk" very well either. Just know that I'm gun shy on cams since I bought and installed one many years ago that made alot of noise but really didn't run very well, definitely nowhere near how I was expecting.

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.

 

[Newbomb Turk]

and "compression ratio effective" on that page is DCR, it would appear that i was harping on about much the same thing without realizing it

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.