gman3850
Member
ya each of his racing heads with 1.2 rockers is like $600 or $400 without rockers
also your phones should now work
Advanced Hemi 212cc Predator Build
- Thread starter bob58o
- Start date
- Status
ya each of his racing heads with 1.2 rockers is like $600 or $400 without rockers
also your phones should now work
Jrgunn5150
Rudderless
- Messages
- 1,028
- Reaction score
- 5
I always go with the higher C/R. I would certainly run premium in it.
bob58o
SuckSqueezeBangBlow
I definitely want to use the 0.027" gasket for 10.65 : 1 compression.
I am uncertain of the V2P clearance because my first attempt at measuring with clay on the piston was less than exact.
I've read anywhere from 0.050" clearance to .110" intake 0.130" exhaust P2V clearance as the minimum.
It is exciting! Can't wait to get it back! Hopefully my next clay measurement will be more precise.
Measure poorly once, cut twice, shim it up to make it right.?!
bob58o
SuckSqueezeBangBlow
I want to thank RK970 (IIRC) for originally suggesting increased compression. Research shows it is awesome! Especially for larger cams!
http://www.musclecardiy.com/cylinde...linder-head-compression-ratios-power-part-12/
This is like the same link I posted above but more complete. It was also in with my Porting adventures thread.
These are some excerpts that I think are applicable to small engine compression and camshafts..
THERMAL EFFICIENCY
"You can now see why a high-compression cylinder produces better power and fuel economy. It is not solely because the charge is squeezed harder and the resulting combustion pressure is increased, but also because the higher expansion ratio allows more energy to be extracted from the original high-pressure charge."
DYNAMIC COMPRESSION LOSS DUE TO CAM
"Because of the delayed intake closure, there is considerable piston motion up the bore from BDC before the intake actually closes. This, at low rpm, pushes some of the mixture back into the intake manifold. This means the volumetric efficiency (breathing efficiency), and thus the effective displacement of the cylinder, is well below 100 percent. In other words, a 100-cc cylinder with a static CR of 10:1 may only trap 75 cc of air. This means the dynamic CR, at about 8.5:1, has dropped well below the static CR of 10:1. The bigger the cam, the more this effect comes into play."
"The following example shows just how much influence the delayed intake closure has on the dynamic CR. Let us take three different duration cams, all having a 108 lobe centerline angle (LCA), and all timed-in at 4 degrees advanced. Along with this, let’s say our static CR measures 12:1. With a 250-degree duration cam, the dynamic CR is in the mid to low 11s. For a cam of some 275-degrees duration, the dynamic CR drops to around the mid 10s. Our 300-degree race cam used with a static CR of 12:1 has a dynamic CR of only about 8.3:1."
INCREASED COMPRESSION AND LONG DURATION CAMS
"From these results we see that, with a 9:1 CR, a 265-degree cam produced (the gray curves of Figure 12.6) some decent results from low RPM on up.
As expected, it started to drop torque by the time 5,000 rpm was being approached and power peaked just shy of 140 hp. This cam was then substituted for a 285-degree cam.
On the same 9:1 CR (blue curves of Figure 12.6) this bigger cam dropped 38 ft-lbs of torque at 1,750 rpm. That amounts to a 32-percent reduction. The extra duration did not start to pay off until 3,750 rpm. From there on up the bigger cam paid off by delivering an increase in peak torque of 4 ft-lbs and almost 26 hp.
At this point, the head was milled to bump the CR to almost 12:1. The results of this move are shown by the green curves in Figure 12.6. As you can see, this increase in compression regained almost all the low-speed torque that was lost. On top of this the big-cam/high-compression combo produced an increase of 15 ftlbs and 33 hp."
"When we go back to the basics, the big increases seen with a combo of more compression and cam are easier to understand. If you check the numbers in Figure 12.4, you see that the biggest gains from a compression increase happen when moving from a low compression to a higher one. Going from 8:1 to 10:1 is worth a theoretical 3.7 percent while raising the compression the same two points from 11:1 to 13:1 is only worth 2.5 percent. This means the bigger the cam, the more responsive it is to an increase in CR, especially in the lower-RPM range."
VALVE SIZE/FLOW VS COMPRESSION
"What is usually not appreciated is that the CR is, for the most part, the controlling factor. Because the high-compression cylinder delivers energy to the crank much earlier in the power stroke, there are implications we can take advantage of. The most obvious is the exhaust valve opening can be made earlier, and it can be held open longer. This can be done for an improved high-RPM output without significantly impacting the engine’s low-speed output. The rule here is that the higher the compression ratio goes, the smaller the exhaust valve needed to get the job done. This in turn leaves more room for a larger intake."
QUENCH VS EMISSIONS
"The quench clearance is the distance the deck of the piston is from the cylinder head face at TDC. Loose (wide) quench clearances can actually promote detonation. Reducing this clearance (by block milling or using a taller piston) can actually stave off detonation by a substantial amount.
If quench is so good at suppressing detonation and allowing the use of higher CRs for more power and better mileage, why doesn’t the factory make it tight to start with? In a nutshell, the answer is EDIT: CALIFORNIA!!! lol Tight quench areas cause unburned hydrocarbon emissions to increase. High-compression ratios bring about a dramatic increase in oxides of nitrogen, which are the primary cause of smog. "
http://www.musclecardiy.com/cylinde...linder-head-compression-ratios-power-part-12/
This is like the same link I posted above but more complete. It was also in with my Porting adventures thread.
These are some excerpts that I think are applicable to small engine compression and camshafts..
THERMAL EFFICIENCY
"You can now see why a high-compression cylinder produces better power and fuel economy. It is not solely because the charge is squeezed harder and the resulting combustion pressure is increased, but also because the higher expansion ratio allows more energy to be extracted from the original high-pressure charge."
DYNAMIC COMPRESSION LOSS DUE TO CAM
"Because of the delayed intake closure, there is considerable piston motion up the bore from BDC before the intake actually closes. This, at low rpm, pushes some of the mixture back into the intake manifold. This means the volumetric efficiency (breathing efficiency), and thus the effective displacement of the cylinder, is well below 100 percent. In other words, a 100-cc cylinder with a static CR of 10:1 may only trap 75 cc of air. This means the dynamic CR, at about 8.5:1, has dropped well below the static CR of 10:1. The bigger the cam, the more this effect comes into play."
"The following example shows just how much influence the delayed intake closure has on the dynamic CR. Let us take three different duration cams, all having a 108 lobe centerline angle (LCA), and all timed-in at 4 degrees advanced. Along with this, let’s say our static CR measures 12:1. With a 250-degree duration cam, the dynamic CR is in the mid to low 11s. For a cam of some 275-degrees duration, the dynamic CR drops to around the mid 10s. Our 300-degree race cam used with a static CR of 12:1 has a dynamic CR of only about 8.3:1."
INCREASED COMPRESSION AND LONG DURATION CAMS
"From these results we see that, with a 9:1 CR, a 265-degree cam produced (the gray curves of Figure 12.6) some decent results from low RPM on up.
As expected, it started to drop torque by the time 5,000 rpm was being approached and power peaked just shy of 140 hp. This cam was then substituted for a 285-degree cam.
On the same 9:1 CR (blue curves of Figure 12.6) this bigger cam dropped 38 ft-lbs of torque at 1,750 rpm. That amounts to a 32-percent reduction. The extra duration did not start to pay off until 3,750 rpm. From there on up the bigger cam paid off by delivering an increase in peak torque of 4 ft-lbs and almost 26 hp.
At this point, the head was milled to bump the CR to almost 12:1. The results of this move are shown by the green curves in Figure 12.6. As you can see, this increase in compression regained almost all the low-speed torque that was lost. On top of this the big-cam/high-compression combo produced an increase of 15 ftlbs and 33 hp."
"When we go back to the basics, the big increases seen with a combo of more compression and cam are easier to understand. If you check the numbers in Figure 12.4, you see that the biggest gains from a compression increase happen when moving from a low compression to a higher one. Going from 8:1 to 10:1 is worth a theoretical 3.7 percent while raising the compression the same two points from 11:1 to 13:1 is only worth 2.5 percent. This means the bigger the cam, the more responsive it is to an increase in CR, especially in the lower-RPM range."
VALVE SIZE/FLOW VS COMPRESSION
"What is usually not appreciated is that the CR is, for the most part, the controlling factor. Because the high-compression cylinder delivers energy to the crank much earlier in the power stroke, there are implications we can take advantage of. The most obvious is the exhaust valve opening can be made earlier, and it can be held open longer. This can be done for an improved high-RPM output without significantly impacting the engine’s low-speed output. The rule here is that the higher the compression ratio goes, the smaller the exhaust valve needed to get the job done. This in turn leaves more room for a larger intake."
QUENCH VS EMISSIONS
"The quench clearance is the distance the deck of the piston is from the cylinder head face at TDC. Loose (wide) quench clearances can actually promote detonation. Reducing this clearance (by block milling or using a taller piston) can actually stave off detonation by a substantial amount.
If quench is so good at suppressing detonation and allowing the use of higher CRs for more power and better mileage, why doesn’t the factory make it tight to start with? In a nutshell, the answer is EDIT: CALIFORNIA!!! lol Tight quench areas cause unburned hydrocarbon emissions to increase. High-compression ratios bring about a dramatic increase in oxides of nitrogen, which are the primary cause of smog. "
ezcome-ezgo
G'me sumthin to write on
Cr ocd
bob58o
SuckSqueezeBangBlow
OCD, aspergers,....
This is all very important stuff! lol
How else am I going propel my Submarine to the center of the black hole?
Jrgunn5150
Rudderless
- Messages
- 1,028
- Reaction score
- 5
Quench is the reason true Hemi head's fell out of style lol.
I can't speak to PTV clearance on these engine's, I'm just not familiar enough.
Where are you at on valvespring pressure vs what is recommended by the cam manufacturer? What usually causes interference is when the valve bounces back up off the seat after closing.
I can't speak to PTV clearance on these engine's, I'm just not familiar enough.
Where are you at on valvespring pressure vs what is recommended by the cam manufacturer? What usually causes interference is when the valve bounces back up off the seat after closing.
bob58o
SuckSqueezeBangBlow
How do you combat that? Stiffer springs? Lighter Springs? Dual Spring Things I saw?
Is This same as valve float and can it be controlled by keeping RPMs lowish (6000)
Cam card says 26lb springs. I have 26 lb springs.
Is this what you are asking, or are you asking about a more specific measured number?
Pressure can be adjusted using shims, reliefs, different length valves/pushrods?..... right?
Poboy kartman
Senior Moments Member
ARRGH!!! STILL GAB!
bob58o
SuckSqueezeBangBlow
ARRGH!!! STILL GAB!
As soon as I get my head back...
Dyno wouldn't take AmEx yesterday and when I called today with a Visa, they were closed. 3pm ET on Fridays. It's like Europe in NC. lol
SO ON Monday, I will pay the ransom to get my head back!
I am off next Saturday and plan on posting some videos!
Hopefully I'll have it sealed and jetted by then and will be pumping out as much "Fury" as 15 Californian Horses.
Let's guess how long a brand new BLAST belt will last on the engine with 30 series.
It is almost complete. For now.
Poboy kartman
Senior Moments Member
How mush you want for the Veesa, Hombre?
bob58o
SuckSqueezeBangBlow
Probably in poor taste...
Chicago classic
"How much for the women?"
https://www.youtube.com/watch?v=JzzE6XLbC8M
---------- Post added at 07:14 PM ---------- Previous post was at 07:11 PM ----------
Every bar / pool hall in TX???
This is what i assume.
https://www.youtube.com/watch?v=ew1sSznDcWA
Poboy kartman
Senior Moments Member
Replace the beer bottles with bullets...and you got it!
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
Holy crap! I just noticed the first waiter is PEE WEE HERMAN!!!!!
AKA Derrrick Fureal!
AKA Derrrick Fureal!
bob58o
SuckSqueezeBangBlow
So I noticed some scratches on top of the piston to go along with the light scoring on the cylinder and the scratch around the intake valve seat I noticed before.
Not sure if the scratches happened while running or while apart, but I'm sure the scoring on the cylinder happened while running. I know some scratches are Ok, but would like to find out what happened.
It seems like I should take the piston out again and look for damage. If I do that, Before I do that... I would like to check compression, but cam has compression release mechanism.
Any ideas on how to spin the crank backwards fast enough for a compression test? The mechanism shouldn't work in reverse.
Or spin the engine at 1500 RPM without a spark plug?
I'm sure I could figure out how to take the compression release apart, but that would obviously a last resort.
Maybe a leak down tester would be better?
---------- Post added at 05:02 PM ---------- Previous post was at 04:47 PM ----------
Or can I just pull the camshaft, lifters, pushrods???
Then pull the rope? hhhmmm???
Not sure if the scratches happened while running or while apart, but I'm sure the scoring on the cylinder happened while running. I know some scratches are Ok, but would like to find out what happened.
It seems like I should take the piston out again and look for damage. If I do that, Before I do that... I would like to check compression, but cam has compression release mechanism.
Any ideas on how to spin the crank backwards fast enough for a compression test? The mechanism shouldn't work in reverse.
Or spin the engine at 1500 RPM without a spark plug?
I'm sure I could figure out how to take the compression release apart, but that would obviously a last resort.
Maybe a leak down tester would be better?
---------- Post added at 05:02 PM ---------- Previous post was at 04:47 PM ----------
Or can I just pull the camshaft, lifters, pushrods???
Then pull the rope? hhhmmm???
Poboy kartman
Senior Moments Member
Nope...(the itake valve has to open to let air in)...but I'm thinking just the exhaust side rocker would do it!
bob58o
SuckSqueezeBangBlow
Good Idea! Once again.
The compression release works by cracking open the exhaust.
The compression release works by cracking open the exhaust.
Now hold just a minute here boys............
Didn't I refer you to them for the head work. He told me it will be 3 weeks before I get mine back. And it looks like your getting yours before me and you sent yours after me. Something ain't right.
bob58o
SuckSqueezeBangBlow
Now hold just a minute here boys............
Didn't I refer you to them for the head work. He told me it will be 3 weeks before I get mine back. And it looks like your getting yours before me and you sent yours after me. Something ain't right.
How much did you ask him to take off?
0.030"?
He said one was sitting on the shelf waiting to go back?
Did you call?
Yeah like a few days ago he told me he's 3 weeks behind. i got a whole Briggs block there for machine work. Boring, valve seats and guides. And whatever it takes to almost break the stock block. It's not exactly in the single digit power range anymore after he's done.
- Status