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Quench vs. C/R vs. Fuel octaine
#502160
10/20/09 04:23 PM
10/20/09 04:23 PM
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I'm in the porocess of building a 383/438 stroker. On the KB calculator my computations come out as follows Heads = 84cc Piston Head volume = 4(valve reliefs on flat top pistons) Gasket Thickness = .029 Gasket Bore -= 4.350 Cylinder Bore = 4.310 Deck clearance = .010 Stroke = 3.750 Computes to STATIC compression of 10.203 adding rod length = 6.760 Valve timing @ 6* Intake closing point = 38* Dynamic CR = 9.472 I am trying to keep the quench at .040 so if I were to use a head gasket of .039 I would have the block decked for 0 deck clearance. Will this run on the 91 octain I have available to me. If not what do I need to do to keep the quench but lower compression (if I have too)? Thanks  Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: Chi_Town_Runner]
#502161
10/20/09 06:56 PM
10/20/09 06:56 PM
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Lincoln Nebraska
RapidRobert
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Quote:
Will this run on the 91 octain I have available to me. If not what do I need to do to keep the quench but lower compression (if I have too)?
With those numbers I believe so and I'd make sure of all my measurements to get em exactly where I want them. If you go w full floating pins you can mock everything up, measure & easily pull the pistons to machine them for an exact zero deck height to go with your .039" gaskets. If needed you can enlarge/polish the chamber(s) with your porting burrs/tootsie rolls. Doesn't take much material to be removed.
Last edited by RapidRobert; 10/20/09 07:07 PM.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: dynorad]
#502163
10/20/09 07:37 PM
10/20/09 07:37 PM
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Columbia, CT
moper
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as it calculated, no. But I think your number for the intake valve closure is off. What cam is it? You need the spec for .050 lift... not .005 or .006 lift....
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: moper]
#502164
10/20/09 07:54 PM
10/20/09 07:54 PM
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They are full floating pins, The cam (not yet purchased) is Comp Cams XR274HR-10 Hydraulic Roller (let the solid guys begin  ) Duration I/E = 274/282 Duration I/E @ .50 = 224/230 Lift I/E = .538/.534 More thoughts Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: 64Post]
#502170
10/20/09 09:57 PM
10/20/09 09:57 PM
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Thanks, Quote:
At 6000' emphasis should be placed on cylinder pressures, otherwise you'll end up with a dog of a motor.
But now how to alter or adjust cylinder pressure without effecting C/R or can't you?
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: RapidRobert]
#502173
10/20/09 11:13 PM
10/20/09 11:13 PM
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The cam has not yet been purchased. I'm taking the block to the machinist on Thursday so at this point I can make any adjustments with no downside. Thanks Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: Chi_Town_Runner]
#502174
10/21/09 08:15 AM
10/21/09 08:15 AM
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U.S.S.A.
JohnRR
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Frank , what heads , iron or alum ? Closed chamber or open ? As far as machining each piston for perfect quench ... first off that's  , second , it's impossible unless he had A CUSTOM piston made because a quench head piston for a 383 stroker DOES NOT EXIST , so if it's the custom the last thing I would be doing is cobbling up a $1000 set of pistons.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: JohnRR]
#502175
10/21/09 09:04 AM
10/21/09 09:04 AM
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Columbia, CT
moper
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Like John said... easier to get tthe machining right then individually fit each piston..
I agree at 6000' you want more squeeze... I confess I'm a sea level guy so how much is too much I am not sure. I do know Comp doesnt publish the intake closing event but you should be able to get it from them by phone if you ask.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: JohnRR]
#502176
10/21/09 09:49 AM
10/21/09 09:49 AM
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Heads 440source stealth 84 cc Pistons are flat top with 2 valve reliefs Compression height 1.320" Thanks for any additional input. I'll be on the phone today to Comp re specs. As I said, the cam has not been purchase yet so I have flexability with that. Any thought on that? I may post a new thread re: cam selection. Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: moper]
#502178
10/21/09 11:13 AM
10/21/09 11:13 AM
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Grand Haven, MI
patrick
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Quote:
as it calculated, no. But I think your number for the intake valve closure is off. What cam is it? You need the spec for .050 lift... not .005 or .006 lift....
 my cam is a little [Email]259@.006[/Email], [Email]208@.050[/Email] hydraulic roller, 112LSA installed at 108, and my intake close point, going by .006" lift advertised is ~57.5 degrees ABDC.... 0.50 duration is 32 degrees ABDC....mine is a 318, 9:1 measured, no quench (.083" quench distance), and runs on 87 octane.
I'm guessing the number you really need to use to determine DCR is going to be closer to 60 deg. ABDC....
EDIT, seeing the cam you choice, 274 .006 intake duration (what comp uses for "advertised duration"), if installed at 106 ICL, would net you an intake close point 63 degrees ABDC, not 38. the KB calculator says to use .050 ICP+15 degrees, which nets 53 deg. ABDC. using .006 numbers you get
8.2 DCR, using the KB method nets 8.8....it should run fine on 92 or 93, you may have to be a little conservative with your distributor's timing curve.
Last edited by patrick; 10/21/09 11:21 AM.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: patrick]
#502180
10/21/09 11:38 AM
10/21/09 11:38 AM
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Patyrick, Very interesting. Here is a link to the cam I was LOOKING at, not yet purchased any. Cam Spec Link I will keep looking at cam profiles to see where I need to go. Keep the info commin.  I only want to do this once. Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: Chi_Town_Runner]
#502181
10/21/09 12:21 PM
10/21/09 12:21 PM
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Joined: Jan 2003
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Grand Haven, MI
patrick
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those numbers given for cam timing are .050 numbers. intake opens 6 degrees BTDC, closes 38 after. 6+180+38=224. intake installed centerline is 106 ATDC, or 74 BBDC. 1/2 of 224 is 112. 112-74= 38. to figure out advertised ICP, just take 1/2 of 274, (137) and subtract 74 137-74=63. can't really build compression until the valve is closed, so IMHO the .006 ICP is a better indicator than the .050 ICP + 15 degrees.... for instance, just in hydraulic roller lobe profiles, look here: http://bulletcams.com/Masters/HRlobes.htmfor 226@.050 lobes, bullet has 10 different profiles with .006 duration ranging from 276 to 293, which assuming the lobes are symmetrical, would mean a .006" intake close point 8.5 degrees later for the 293 over the 276....these lobes also have an 18 degree range (133 to 151) of .2" lift duration.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Quench vs. C/R vs. Fuel octaine
[Re: 64Post]
#502183
10/21/09 01:46 PM
10/21/09 01:46 PM
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Patrick & 64 Post and anyone else who is not as mathematically challenged as I, What are your suggestions? Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: 64Post]
#502184
10/21/09 02:08 PM
10/21/09 02:08 PM
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Grand Haven, MI
patrick
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Quote:
Quote:
you get
8.2 DCR, using the KB method nets 8.8....it should run fine on 92 or 93, you may have to be a little conservative with your distributor's timing curve.
Does this number take into account his altitude? If not, he's going to end up with a DCR of about 6.5 and a SCR in the high 7s.
And, I don't like the cam... the ramps are too slow for a roller. Get something in the 35º range using the .050" numbers.
ETA: I did some rough calcs using 60º as the ICA, a 10.5 SCR and 6000' of altitude. Your cranking pressure is only 140 psi. That's not going to get it done, Frank.
no, I just plugged the IVC point in the calculator. the calculator doesn't account for altitude/air pressure...either way, the compression RATIO is the same, it's just the CYLINDER PRESSURE that's lower at altitude.
also, you can't judge a cam's aggressiveness just by the advertised and .050 numbers. Hydraulic rollers a lot of time "look" less aggressive becasue they usually have slowish opening ramps.
for comparison, let's compare this cam to some hydraulic flat tappets, looking in the comp cams master lobe guide
the comp XE274's intake:
274@.006" dur, 230@.050 dur, 143@.2" dur, .325" lobe lift.
the XE275HL's intake lobe has these specs:
275@.006" dur, 231@.050 dur, 149@.2" dur, .35" lobe lift.
it looks like the cam he's looking at is using comp's XFI lobes, which are amongst the most aggressive hydraulic roller lobes I've seen, and which according to the catalog spec like this for the intake:
274@.006" dur, 224@.050 dur, 149@.2" dur, .358" lobe lift
so for a given .006 duration, the roller has 6 & 7 degrees less than the .842/.904 dia flat tappet lobe, but 6 degrees more, and the same .2" duration, and more lift than both....I'd say that's an aggressive lobe.
lets compare to some solids. can't directly compare advertised numbers, since comp uses .015" lift duration as advertised duration for solids. let's compare to a .842" dia XE solid lobe, which looks like this:
rated dur (.015" lift), .050 dur, .2 dur, lobe lift
262/224/135/.319"
274/236/147/.335"
so it looks like the juice roller's lobe is more aggressive than an aggressive .842" solid flat tappet lobes in terms of .2" dur and lift compared to .050 duration......
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Quench vs. C/R vs. Fuel octaine
[Re: Chi_Town_Runner]
#502185
10/21/09 02:23 PM
10/21/09 02:23 PM
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Grand Haven, MI
patrick
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Quote:
Patrick & 64 Post and anyone else who is not as mathematically challenged as I,
What are your suggestions?
Frank
you are fine. should make a great street motor, should be strong from 1500-5500 RPM. I'd expect the power to peak below 6K RPM. it probably will run on 89, will definitely run on premium.
there's guys with KB107 equipped 360 shortblocks and magnum heads with tight quench (~10.6:1 comp, with iron heads) running comp XE268's and running on premium, can get by with 89 without an overly aggressive dizzy timing curve.
granted, the smaller bore helps slightly with detonation resistance, too...
anecdotally, a friend has a stroker LT1 in his impala SS, 396", with a 230@.050 duration comp hydraulic roller (probably in the 280 adv range), and 11.7:1 measured static compression, and he runs ok on pump premium. it's a little finicky, as the computer sometimes pulls a little timing out on warm days if he fills up anywhere but the shell station that sells 93 octane....
plugging the numbers in on his combo to the K-B DCR calculator, I get a DCR of 9.4-10 depending on using .006 vs. .050+ 15 ICP....granted he has better fuel/spark control running a EFI....
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Quench vs. C/R vs. Fuel octaine
[Re: patrick]
#502186
10/21/09 06:22 PM
10/21/09 06:22 PM
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Aurora Colorado
BELVEDERE67
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I've been watching this post with interest. You all are correct in the choice of cam. Hyd. Roller profiles are more aggresive than a solid ft. However, I think the post while valid, isn't going after the most important item :: cyl pressure. It is very difficult to develop needed cyl. press. The planned motor, w/o the cam is suspect to me. Static compression ratio needs to go up. With alu. heads to 12 to 1. I had an iron headed 383 at 11.7 static cr and moderately aggressive cam with quench @ .040 that ran w/o any detonation. But it was still underpowered up here. Consider that we lose an average of .9 sec on a good day of quarter mile times because of air density/cylinder pressure when compared to sea level. Many times our DA is 8000-9000 ft. Generic power loss is on avarage 20%. No cam profile is going to make that much up. So to plan this out correctly IMHO, Up the static compression ration to 12/1 and .040 quench and use that roller you have posted. My experience says you will still be fine on detonation AND you will have a build that will scream. I will also add that that cam seams a little small. I've now got a Solid ft that is much more agressive than whats posted in a 470.  
Last edited by BELVEDERE67; 10/21/09 06:35 PM.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: patrick]
#502187
10/21/09 06:50 PM
10/21/09 06:50 PM
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Baltimore/Denver
64Post
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Quote:
Quote:
Quote:
you get
8.2 DCR, using the KB method nets 8.8....it should run fine on 92 or 93, you may have to be a little conservative with your distributor's timing curve.
Does this number take into account his altitude? If not, he's going to end up with a DCR of about 6.5 and a SCR in the high 7s.
And, I don't like the cam... the ramps are too slow for a roller. Get something in the 35º range using the .050" numbers.
ETA: I did some rough calcs using 60º as the ICA, a 10.5 SCR and 6000' of altitude. Your cranking pressure is only 140 psi. That's not going to get it done, Frank.
either way, the compression RATIO is the same, it's just the CYLINDER PRESSURE that's lower at altitude.
Exactly! What I'm trying to emphasize here is cylinder pressure is critical at higher altitude. For example, if 165 psi is the limit for 91 pump gas at sea level, then that is the target that should be hit @ 6000'.
Quote:
also, you can't judge a cam's aggressiveness just by the advertised and .050 numbers. Hydraulic rollers a lot of time "look" less aggressive becasue they usually have slowish opening ramps.
I acknowledge rollers are more efficient and do promote higher VE. But, you can't build a 10:1 SCR sea level engine and expect a roller cam alone to make up the 25% loss @ 6000', and we haven't even brought up DA which on some days will be 8,000'-10,000'. Personally I haven't seen any empirical data that quantifies a given percentage increase in VE over a similar solid cam. But let's say there is a 5% increase in cylinder filling using the roller. It still leaves the OP way short on cylinder pressure if he is starting out @ 140psi.
Also DCR is not a panacea. Sure at lower rpm it's a factor, but once the revs go up SCR becomes the dominating factor.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: BELVEDERE67]
#502188
10/21/09 10:24 PM
10/21/09 10:24 PM
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I really do appreciate all the information I'm getting on this. The 12:1 compression ratio scares me a little. I live at the 6000 ft level but I want to be able to take this car on the road. Any which way I go, N-S-E-W, I decrease my altitude. This car is not going to the track on any regular basis but I will do some traveling with it, so I am willing to sacrafice some HP for drivability at lower altitudes. I guess I'm looking for a compromise that I think has eluded all of us and don't know if it's attainable. Belvedere67, I listen to your comments with great interest, and respect your input since your in Colorado and have altitude expierence. The only way I can see uping the static C/R at this point is to mill the heads. Tomorrow, I'm going to the machinist and since the heads aren't in yet we'll just concentrate on the bottom end. I'll go for zero deck and hope to get more input here. Thanks to all, I'll be standing by. Frank
Remember - 2 wrongs don't make a right - but 3 rights make a left!
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Re: Quench vs. C/R vs. Fuel octaine
[Re: BELVEDERE67]
#502190
10/22/09 02:12 AM
10/22/09 02:12 AM
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Joined: Jan 2003
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Balt. Md
383man
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Quote:
I've been watching this post with interest. You all are correct in the choice of cam. Hyd. Roller profiles are more aggresive than a solid ft. However, I think the post while valid, isn't going after the most important item :: cyl pressure. It is very difficult to develop needed cyl. press. The planned motor, w/o the cam is suspect to me. Static compression ratio needs to go up. With alu. heads to 12 to 1.
I had an iron headed 383 at 11.7 static cr and moderately aggressive cam with quench @ .040 that ran w/o any detonation. But it was still underpowered up here.
Consider that we lose an average of .9 sec on a good day of quarter mile times because of air density/cylinder pressure when compared to sea level. Many times our DA is 8000-9000 ft. Generic power loss is on avarage 20%. No cam profile is going to make that much up.
So to plan this out correctly IMHO, Up the static compression ration to 12/1 and .040 quench and use that roller you have posted. My experience says you will still be fine on detonation AND you will have a build that will scream.
I will also add that that cam seams a little small. I've now got a Solid ft that is much more agressive than whats posted in a 470.
That is right as the cyl pressure is the bottom line that all of this effects and at sea level I would not push it mover 200 if you want to run on pump. In fact I like to keep it around 180 for pump at sea level. I am not sure at you elevation. But I can say at sea level I would not hesitate to run 11.5 comp with aluminum heads and quench as with the right cam you can run on 92 or 93 pump. My sons 400 has Eddy RPM heads and I cut them to get his 400 at almost 10.8 and it does not have good quench as his pistons are down about .023 and it has the .039 head gaskets. But we run 38 total timing with no ping at all. Aluminum heads can usually run about 1 point higher in comp. But you need to watch where the cyl pressure comes out. A good cam company can help with that. Good luck , Ron
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Re: Quench vs. C/R vs. Fuel octaine
[Re: RapidRobert]
#502192
10/22/09 02:47 AM
10/22/09 02:47 AM
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Baltimore/Denver
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Quote:
Quote:
For example, if 165 psi is the limit for 91 pump gas at sea level, then that is the target that should be hit @ 6000'.
yes if 165 is the limit for 91 inside the cyl(s) it doesn't make any difference if the cyl(s) are located in New Mexico or death valley but since the air outside the cyls is "thinner" at NM you need more CR to squeeze this thin air inside the cyl(s) to get that 165
Correct, and that's why we generally add 2 points (maybe more depending on the other usual factors) of static CR to a "sea level" type build and then fine tune the cylinder pressures with the cam shaft. All of the various on line calculators make this a pretty simple task nowadays.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: 64Post]
#502193
10/22/09 03:08 AM
10/22/09 03:08 AM
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Lincoln Nebraska
RapidRobert
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64Post do you have a ballpark psi recommendation for me for 87 octane. My daily driver mileage build is coming together & I have not finalized the scr or the cam. Lincoln Nebraska is ~1200 ft & I will be taking no trips
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Re: Quench vs. C/R vs. Fuel octaine
[Re: RapidRobert]
#502194
10/22/09 10:57 AM
10/22/09 10:57 AM
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Aurora Colorado
BELVEDERE67
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Your additional info on how you plan to use that good looking RR does change how aggressive the cam should be. To answer your question on milling the heads : yes. I used the calculator in this post with your bore and stroke and added a 77 cc combustion chamber with the other provided numbers and came up with 11.3 SCR. I have a set of Eddy's that were milled to 77cc's. Considering that the intake face needs to be milled as well, that may be as much as you can go with a street application. The valve cover rail get a little small for sealing. So, even with the zero deck and the head milling, you still are well below that 12 to 1 number your concerned about. Just to let you know you may not be able the get the compression high enough and be safe in a street app. You may be spot on with your cam choice even tho it does seem to be a little small. Bear in mind that a stroker motor (this may not be one) does like or eat up cam duration. So this is a consideration for you.......like you need another question..............right? 
Last edited by BELVEDERE67; 10/22/09 10:59 AM.
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Re: Quench vs. C/R vs. Fuel octaine
[Re: RapidRobert]
#502195
10/22/09 03:24 PM
10/22/09 03:24 PM
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Baltimore/Denver
64Post
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Quote:
64Post do you have a ballpark psi recommendation for me for 87 octane. My daily driver mileage build is coming together & I have not finalized the scr or the cam. Lincoln Nebraska is ~1200 ft & I will be taking no trips
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