Re: Super duper gas miledge 273 experiment !!!
[Re: Clair_Davis]
#47587
11/28/07 09:12 AM
11/28/07 09:12 AM
|
Joined: Jan 2003
Posts: 14,610 Not2farfromNashville, TN
Rug_Trucker
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
|
We'll need to keep this thread rolling as Dave is moving to Montana today. Unless plans have changed.
I think he's going to raise himself up a crop of dental floss..........
Safe trip Dave and family!
"The only thing to do for triumph of evil is for good men to do nothing"
"NUNQUAM NON PARATUS!"
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: Rug_Trucker]
#47588
11/28/07 12:35 PM
11/28/07 12:35 PM
|
Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
another thing to consider, I've read the closer the valve is to the cylinder side, the more swirl is induced from that shrouding. on a 273, anything larger than the stock 1.78/1.5 valves require bore notching to avoid a collision between the valve and cylinder bore, so the shrouding effects will probably be about the same regardless of head/valve size. on a 318's 3.91" bore, the magnum's 1.92/1.625" valves may give them an additional boost in induced swirl over a 273 head or '302 head with the small 1.78/1.5 valves...
I'm still not convinced the 273 will give any significant mileage improvement over a similarly built 318. for cost and ease of parts aquisition, I still think a 318 (roller cam block) is the way to go, especially if trying to optimize power and economy.
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)
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: patrick]
#47589
11/28/07 01:09 PM
11/28/07 01:09 PM
|
Joined: Jan 2003
Posts: 7,131 Amarillo, Texas
BBR
master
|
master
Joined: Jan 2003
Posts: 7,131
Amarillo, Texas
|
What 273 heads does he have? Open chamber 67-69's or the earlier closed chamber models with the funky bolts?
If it's the open chamber, I certainly go with the 302's just for the sake of squeezing a better CR out of the thing with minimal hassle.
I would think as far as rear end ratio goes, you would want to choose it (and your tire size) so that your target cruise rpm equals your peak torque rpm, eh?
Drag Week 2011 - 77th place - DD Drag Week 2012 - 2nd place SRBB N/A Drag Week 2014 - Kapooya RMRW 2018 RMRW 2020
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: dart4forte]
#47590
11/28/07 01:54 PM
11/28/07 01:54 PM
|
Joined: Feb 2003
Posts: 16,161 Mesa, Arizona
dart4forte
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 16,161
Mesa, Arizona
|
Quote:
Quote:
The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...
I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.
Here are the numbers off my head. i tried to scan the test data but it wouldn't show in color and was impossible to read. I'll try and explain what is depicted on the sheet.
Used a 302 Swirl port vs the stock 273. both had the same modifacations except we stayed with the stock intake size on the 302 and only modified with a stainless valve. The 273 used a cut 1.88 stainless valve down to 1.84. We found this size ideal for the 273 to prevent shrouding.
First test
273 with a 1.84 intake, 1.56 exhaust with alittle bowl work Same on the 302 except larger intake and exhaust valve. 113% max velocity on both heads
2nd test
273 head with same mod with the addition of more port work, 70 degree bowl cut and 3 angle valve job. 302 the same, both had Ferra valves
Gained 116% on the 273 and 115% on the 302
1st test
The flow numbers showed a big differance with the 273 showing max flow of 166.9 cfm at .400 of lift with the flow curve remaining steading and not falling off until .475 of lift.
The 302 however showed a max of 161.8 and started to fall off at around .500 lift
2nd test
273 showed 169 cfm at .450 lift where the 302 showed 163 cfm at .450 then dropping off.
273 and 302 had the same modifacations.
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: dart4forte]
#47591
11/28/07 04:51 PM
11/28/07 04:51 PM
|
Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
Quote:
Quote:
Quote:
The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...
I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.
Here are the numbers off my head. i tried to scan the test data but it wouldn't show in color and was impossible to read. I'll try and explain what is depicted on the sheet.
Used a 302 Swirl port vs the stock 273. both had the same modifacations except we stayed with the stock intake size on the 302 and only modified with a stainless valve. The 273 used a cut 1.88 stainless valve down to 1.84. We found this size ideal for the 273 to prevent shrouding.
First test
273 with a 1.84 intake, 1.56 exhaust with alittle bowl work Same on the 302 except larger intake and exhaust valve. 113% max velocity on both heads
2nd test
273 head with same mod with the addition of more port work, 70 degree bowl cut and 3 angle valve job. 302 the same, both had Ferra valves
Gained 116% on the 273 and 115% on the 302
1st test
The flow numbers showed a big differance with the 273 showing max flow of 166.9 cfm at .400 of lift with the flow curve remaining steading and not falling off until .475 of lift.
The 302 however showed a max of 161.8 and started to fall off at around .500 lift
2nd test
273 showed 169 cfm at .450 lift where the 302 showed 163 cfm at .450 then dropping off.
273 and 302 had the same modifacations.
what bore was that tested on, a 273 bore, or a 318 bore, or a 4" (360) bore?
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)
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: dart4forte]
#47593
11/29/07 09:17 AM
11/29/07 09:17 AM
|
Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
when heads are flowed on a flow bench, they're allways bolted down to a bore plate simulating the cylinder sidewall, and yes, it will make a difference in flow, as the valve gets closer to the cylinder wall, it will be shrouded more, and recorded flow will drop. IIRC Ryan J did a flow test of a set of heads on like a 4.25" bore plate and the same heads on a 4" bore plate, and he saw over a 10% decrease in flow between the tests, IIRC.
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)
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: patrick]
#47595
11/29/07 03:54 PM
11/29/07 03:54 PM
|
Joined: Feb 2003
Posts: 1,665 Milwaukee, WI
Prince_Valiant
top fuel
|
top fuel
Joined: Feb 2003
Posts: 1,665
Milwaukee, WI
|
Quote:
when heads are flowed on a flow bench, they're allways bolted down to a bore plate simulating the cylinder sidewall, and yes, it will make a difference in flow, as the valve gets closer to the cylinder wall, it will be shrouded more, and recorded flow will drop. IIRC Ryan J did a flow test of a set of heads on like a 4.25" bore plate and the same heads on a 4" bore plate, and he saw over a 10% decrease in flow between the tests, IIRC.
I think he was just pointing out that with the same valve size b/w the 273 heads and 318 #302 heads, even if the flow is affected (which it is), it would affect both heads the same, so the comparison is valid.
However, I agree, anytime flow is tested, I like to know the bore size
1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph 1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD) 1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD) 1989 Shelby CSX #500/500
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: Prince_Valiant]
#47596
11/29/07 05:17 PM
11/29/07 05:17 PM
|
Joined: Feb 2003
Posts: 16,161 Mesa, Arizona
dart4forte
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 16,161
Mesa, Arizona
|
I'll have to ask. He stopped by yesterday with the printout. Since I was there when he did the test I do know he used the same bore plate. Just for information the heads I put on the 273 had a bit more work than the heads he used for the comparrison test. My heads had a 70 degree bowl cut with a lot of blending and removing any sharp edges, removed sharp edges on int. and exh ports. Did a short turn radius cut around valve guides and a 30,45,60,70 degree cut on the intake valve (1.84) and a 15,45,60,79 on the exh. Used Ferra valves. Got 116% max velocity and they flowed 169.1 cfm at .500 of lift.
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: dmerc]
#47598
11/29/07 08:22 PM
11/29/07 08:22 PM
|
Joined: Feb 2003
Posts: 16,161 Mesa, Arizona
dart4forte
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 16,161
Mesa, Arizona
|
Quote:
This is an interesting thread. I have 273 heads on a 318 Duster. Has identical mods as yours and I ran a 15.9 (at 5000ft) with it. My next project is a 318 Volare that I'm going to put 273 heads on. I'm going to use the 2 barrel single plane intake that goes with the 273 heads and see what kind of mileage I can sqeeze out of it. I just like those 273 heads! They are lighter too and they don't seem to crack or warp like the 302's
I have a good friend and engine builder that is a class racer. He raced a 273 car years back and now races a 340 Duster. One can actually make the 273 scream. there's a Stock Eliminator racer by the name of Wong that races 273 cars and gets them into low numbers.
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: patrick]
#47599
11/29/07 10:21 PM
11/29/07 10:21 PM
|
Joined: Feb 2003
Posts: 16,161 Mesa, Arizona
dart4forte
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 16,161
Mesa, Arizona
|
Quote:
Quote:
Quote:
Quote:
The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...
I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.
Here are the numbers off my head. i tried to scan the test data but it wouldn't show in color and was impossible to read. I'll try and explain what is depicted on the sheet.
Used a 302 Swirl port vs the stock 273. both had the same modifacations except we stayed with the stock intake size on the 302 and only modified with a stainless valve. The 273 used a cut 1.88 stainless valve down to 1.84. We found this size ideal for the 273 to prevent shrouding.
First test
273 with a 1.84 intake, 1.56 exhaust with alittle bowl work Same on the 302 except larger intake and exhaust valve. 113% max velocity on both heads
2nd test
273 head with same mod with the addition of more port work, 70 degree bowl cut and 3 angle valve job. 302 the same, both had Ferra valves
Gained 116% on the 273 and 115% on the 302
1st test
The flow numbers showed a big differance with the 273 showing max flow of 166.9 cfm at .400 of lift with the flow curve remaining steading and not falling off until .475 of lift.
The 302 however showed a max of 161.8 and started to fall off at around .500 lift
2nd test
273 showed 169 cfm at .450 lift where the 302 showed 163 cfm at .450 then dropping off.
273 and 302 had the same modifacations.
what bore was that tested on, a 273 bore, or a 318 bore, or a 4" (360) bore?
Got an answer for you. They were tested on a 4" bore plate
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: Rug_Trucker]
#47600
11/30/07 12:04 AM
11/30/07 12:04 AM
|
Joined: Feb 2003
Posts: 4,204 Fort Worth, TX
Clair_Davis
master
|
master
Joined: Feb 2003
Posts: 4,204
Fort Worth, TX
|
Quote:
I think he's going to raise himself up a crop of dental floss..........
I hope he saves the wax...
BTW, I hate to ask a pretty basic question this late in the thread, but what exactly is this "115% max velocity" stuff referring to? I guess I haven't seen this terminology before...
Clair
|
|
|
Re: Super duper gas miledge 273 experiment !!!
[Re: Clair_Davis]
#47601
12/05/07 08:47 AM
12/05/07 08:47 AM
|
Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
|
Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
|
for a "SuperDuper MPG experiment" wouldn't the octane tolerance of a cylinder head and piston crown combination be more important than any swirl numbers? I know swirl can improve fast burn, and fast burn can improve octane tolerance, but the stuff I have seen says that 'old fashioned' quench area works better but that modern cylinder heads have had to cut back on quench area due to pollution concerns related to NOx Porsche engineer May's HE "Fireball" high quench area head for Jaguar's V12: http://www.jagweb.com/jagworld/v12-engine/page3.htmlLarry Widmer's 'Soft Head' article (aka TOO or "The Old One") http://www.theoldone.com/articles/The_Soft_Head_1999/the Aussie view of pinging & detonation: http://autospeed.com/cms/A_0601/article.html
|
|
|
Re: Super duper gas miledge 273 experiment !!! UPDATE
[Re: HotRodDave]
#47602
01/01/08 11:10 PM
01/01/08 11:10 PM
|
Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
OP
I Live Here
|
OP
I Live Here
Joined: Jan 2005
Posts: 12,423
Kalispell Mt.
|
Well I picked up a 318 block today and was going to have it zero decked and use some 68 style stock pistons and 340 rods. I carried it all to the machine shop to mill a bunch off the deck and the guy gave me a really good super dooper screaming deal on a set of KB 167 pistons .030 over so I will be useing this short block with the SCAT I beams from my busted stroker. The pistons are 100g lighter a piece and the rods were 115g lighter each, also I should lose even more weight from balancing it and make a very light rotateing assy. It should be easy enough for every one to copy also. For the top end I am going to put on some 302 heads, I have not decided if I am going to put in some 1.88 valves I have around here but there won't be much porting going on. Mabey put on a groove in the chambers for good measure For a cam I have a 273 2bbl solid cam lifters and rockers I will use. I have an LD4B or Holley street dominator to pick from. I am still hopeing to find a offy dual port I will run a small Thermo-quad and my car already has TTI headers so soon I should have this thing goin. I will probably drive it like this for a little bit before I put in an OD trans. It has 2.76 gears right now. Any one want to venture what improvement just the motor will give me from my stock 68 318 2bbl?
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
Re: Super duper gas miledge 273 experiment !!! UPDATE
[Re: HotRodDave]
#47603
01/01/08 11:25 PM
01/01/08 11:25 PM
|
Joined: Jan 2003
Posts: 4,820 near Alexandria, VA
Gas_Bandit
master
|
master
Joined: Jan 2003
Posts: 4,820
near Alexandria, VA
|
I don't think a lighter rotating assembly is going to save you any noticeable mpg. Acceleration will be better, but cruising, you are already spinning the rotating assembly. It sounds like you are building more or less how the 318s came from the factory in the 80s, w/ a tiny solid cam.
2003 Mercury Marauder, 34k miles, 3.73s and custom flash tuned 1981 Camaro, 350 w/ Holley Stealth Ram MPEFI, Sportsman heads, roller cam, self-burned chips, wideband O2 1983 Firebird TA 1993 Saturn SL2 83k
|
|
|
Re: Super duper gas miledge 273/318 experiment !!! UPDATE
[Re: HotRodDave]
#47606
01/25/08 01:36 AM
01/25/08 01:36 AM
|
Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
OP
I Live Here
|
OP
I Live Here
Joined: Jan 2005
Posts: 12,423
Kalispell Mt.
|
Fired it up today!!!
Here is what I have
68 318 block .030 over KB 167 pistons .005 down .039 felpros Scat I beam rods Balanced rotateing assy (very light) 273 2bbl solid cam, lifters and rockers full grooved mains 302 casting heads with all sharp spots smoothed down LD4b intake 850 thermo-quad 904 LU with low 1st and 2nd 2.76 gears No PS No AC Electric fan TTI step headers 10 degrees at idle and 30 total and no vacume advance yet, I don't want it detonateing when I can't here it because of the exhaust.
and that is where it ends, no exhaust after the hearers. It revs real quick but it is sounding lean over 3500 rpm with a bunch of bucking and coughing. It hesitates if you hit it too hard also. I will try doing some carb tuneing tommorow. I may try to get an exhaust on it first though.
What size pipes should I run on this thing, any thoughts???
Any other sugestions???
I am not causing global warming, I am just trying to hold off a impending Ice Age!
|
|
|
|
|