Pump gas with 11:1 compression?
07-21-2016, 03:26 PM
#41
Melting Slicks
A magneto looks like a tall distributor. Tall because the lower section is a generator (power source) and the top was a dual points under a rotor cap. They generally had locked timing and no vac advance. I was a pit crew person and at a young age I thought how stupid!!!!!!
Adam
07-21-2016, 03:30 PM
#42
Colder plugs to prevent the plugs from becoming an unintentionally early ignition source. This can be a big deal in forced induction applications but I've benefited from it in NA engines too.
07-21-2016, 03:33 PM
#43
Melting Slicks
Thread Starter
I'll dig into the distributor to see where I ended up. I agree with Kubs about the advantage of having the timing controlled by a programmable computer. I have an MSD Digital distributor in the 11.5 car. IIRC it gives 20 different mechanical timing curves and ten vacuum curve by turning two dials. I knew setting up the ignition curve would be tedious with this car and today's gas. I have an MSD Boost retard box in a 6-71 car with 9.5:1 compression. I like that better because I can create any (even non-linear) curve I want. As I mentioned the curves that worked well in the first four gears were too much for overdrive. I bet if higher octane was available I could speed up the curve and pick up some mileage. I do pay close attention to feedback the car is giving and never overload it at low RPM. I'm pretty sure that somebody could hurt this engine if they did not know how to drive a high compression set up. This would be an appropriate case for drive by wire that would not allow overly aggressive throttle application in high load low RPM conditions.
I built a 10.7:1 377 for a friend with similar set up. It had something like a 3.4 ring an pinion with the same .64 OD (mine's a 4:11). We could get down to 1500 RPM in fifth with his. By 1800 you could ease in the throttle and start pulling quite well. His cam was similar but 112 LSA vs my 110 LSA, installed with four degrees advance vs my two degrees. His also had a Performer RPM Air Gap vs my Victor JR with a 1" spacer.
I think his typically gets 2-3 more MPG than mine. I get about 14 consistently. I'm in the Ozarks and the hills hurt the mileage and are a factor in the ignition curves. I've tuned cars that are pretty happy right up until we try to climb a hill in OD.
I built a 10.7:1 377 for a friend with similar set up. It had something like a 3.4 ring an pinion with the same .64 OD (mine's a 4:11). We could get down to 1500 RPM in fifth with his. By 1800 you could ease in the throttle and start pulling quite well. His cam was similar but 112 LSA vs my 110 LSA, installed with four degrees advance vs my two degrees. His also had a Performer RPM Air Gap vs my Victor JR with a 1" spacer.
I think his typically gets 2-3 more MPG than mine. I get about 14 consistently. I'm in the Ozarks and the hills hurt the mileage and are a factor in the ignition curves. I've tuned cars that are pretty happy right up until we try to climb a hill in OD.
I know what you mean about hurting the car if you don't know how to drive it. I took the power steering and power brakes out, put in a full manual reverse vb trans, and loud mufflers to keep the wife out of it.
Last edited by The Money Pit; 07-21-2016 at 03:33 PM.
07-21-2016, 03:45 PM
#44
Team Owner
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St. Jude Donor '05
do pay close attention to feedback the car is giving and never overload it at low RPM.
some equate lugging the motor with "saving" it drives me nuts riding with someone who does that
eesh, its a performance car what are they thinking
Last edited by cv67; 07-21-2016 at 03:46 PM.
07-21-2016, 04:00 PM
#45
As long as you are only giving light throttle application a lot of performance builds can run well below 2000 RPM in overdrive. BUT if you mash gas down there you're asking for trouble. Since I started adding OD to old school cars I've found that tuning for low RPM in OD takes the majority of my time and effort. I am looking forward to playing with the cammed LS3/T56/Megasquirt that I put in a '69.
07-21-2016, 05:02 PM
#46
Running 10.85 to 1 compression in my Dart 400. No issues if the temperature is under 90 degrees. If it's over 90 degrees and no or very low humidity sometimes get a slight ping on 93 octane pump gas.
07-21-2016, 06:30 PM
#47
Safety Car
Over the past several months I've been wrestling with the idea of upgrading the AFR 195 heads(non Eliminators) on my 406 to the new 210 Eliminators.....and I think I'm about ready to pull that trigger.
The question I have is chamber size options. I now run 75 cc chambers, and with that I calculate a 10.1:1 compression ratio....verified by my machinist years ago. I run a flat tappet solid cam with 254@.050 duration, and 36 degrees locked out timing. Never pings, starts like a new car, and overall performance is great. The 210's are available with either 65, or 75 cc chambers, and I am tempted to try 65 cc to raise the compression to 11:1, and for the mean time....keep the same cam.
I'm thinking it'll work fine because of the cam duration, but want to hear from those that are running similar combinations. Also in the future I do plan on doing a solid roller cam, but with less duration, so that needs to be considered also. And really long term.....a 427 short block,.....but the wife doesn't know that's coming yet.
The question I have is chamber size options. I now run 75 cc chambers, and with that I calculate a 10.1:1 compression ratio....verified by my machinist years ago. I run a flat tappet solid cam with 254@.050 duration, and 36 degrees locked out timing. Never pings, starts like a new car, and overall performance is great. The 210's are available with either 65, or 75 cc chambers, and I am tempted to try 65 cc to raise the compression to 11:1, and for the mean time....keep the same cam.
I'm thinking it'll work fine because of the cam duration, but want to hear from those that are running similar combinations. Also in the future I do plan on doing a solid roller cam, but with less duration, so that needs to be considered also. And really long term.....a 427 short block,.....but the wife doesn't know that's coming yet.
07-21-2016, 09:25 PM
#48
Safety Car
Many options can hold off pinging. Keeping the engine at 160-170 degrees, aluminum heads, new cam with more duration and if the motor is apart. Knock down any peaks or edges.
Most new performance oriented cars are running 11:1 without any problems. 93 octane is your best bet but I know some areas don't offer it.
Most new performance oriented cars are running 11:1 without any problems. 93 octane is your best bet but I know some areas don't offer it.
07-21-2016, 09:30 PM
#49
Melting Slicks
Thread Starter
You need to figure the dynamic compression ratio, 8 to 8.1 is the highest you'll want to go with out running into detonanation issues and if you stay between the 7.9 to 8.0 you should be fine. With that being said, why the bump in compression if your not planning on more camshaft, the bump in compression by its self is worth 3% in horse power gains so if your making 600 it's 18 horse on just the compression. Now then if your going up in compression to go up in camshaft the just keep your dynamic in check and you'll be fine and the gains of all three would net a large gain.
07-21-2016, 09:35 PM
#50
Melting Slicks
Thread Starter
When I originally started trying to recurve the timing I had similar results when it was super hot out.
Now I have a 1 1/4" tube dual core aluminum radiator and run a single 16 inch Spal fan, and a 160 T-stat. Pretty much stays at 160 unless it's over 90 degrees out, and I get stuck in traffic.
07-21-2016, 09:45 PM
#51
Safety Car
The thing is that new performance cars have a computer and a knock sensor and have the ability to retard the timing, so if the computer detects detonation it retards the timing back enough so that it don't ping. Plus the computer takes 5 to 7 readings per second from the o2 sensor and keeps the fuel in the zone that the engine runs the best and avoids detonation, going lean will cause detonation in short order. My 6.2L in my sierra is 10.5 to one and I've only heard it ping once and that was with crappy fuel and pulling a trailer out on the Denali highway with lots of tall hills. Technology is amazing these days. Guys like Pauldana and Diehard(Tony) have the fast fuel injection systems on their hot rod and all though I don't think that they have knock sensors, their fuel system keeps the fuel ratio optimized and if it werent for the price that would be the way to go. I can put a blower on my truck with the 10.5 to 1 and between the knock sensor and the fuel system run 6 to 8 lbs of boost, it would be so tough to do that on a antique fuel and timing system even with a meth water injection and boost/timing retard box.
Last edited by bluedawg; 07-21-2016 at 09:47 PM. Reason: Third grade pucktuation and shittty spelling...Awe crap forgot my add meds again.
07-22-2016, 02:11 PM
#52
Melting Slicks
My 406 in my signature runs 11.8 to 1 compression ratio. I haven't got the 75 Vert running with this engine in it yet, but I put a few thousand miles on it when it and the 700R4 were in my 80 Vette. I ran it on 93 octane and had no problems.
The squish is set tight, .034". A tight squish (quench) helps, as does a very good cooling system and very careful tuning. Cold air intake helps a lot too, although I did not have one on the 80. The 75 I have an L88 hood with functional air chamber.
The engine likes a somewhat rich idle, 13 to 1, at part throttle cruise I ran 14.2 to 1, and wide open 12.8.
Timing was 16 initial with 6 degrees of ported vacuum and 34 degrees total all in at 3000.
The only time it ever pinged was once when I got stuck in a traffic jam with the temps in the high 90's. When I first got moving from the traffic, it pinged, but after moving down the road a ways and cooled down, it quit pinging.
These are the specs my engine liked, they may not work as well for another combination. I got great gas mileage, tremendous throttle response and it ran like a scalded dog!
The squish is set tight, .034". A tight squish (quench) helps, as does a very good cooling system and very careful tuning. Cold air intake helps a lot too, although I did not have one on the 80. The 75 I have an L88 hood with functional air chamber.
The engine likes a somewhat rich idle, 13 to 1, at part throttle cruise I ran 14.2 to 1, and wide open 12.8.
Timing was 16 initial with 6 degrees of ported vacuum and 34 degrees total all in at 3000.
The only time it ever pinged was once when I got stuck in a traffic jam with the temps in the high 90's. When I first got moving from the traffic, it pinged, but after moving down the road a ways and cooled down, it quit pinging.
These are the specs my engine liked, they may not work as well for another combination. I got great gas mileage, tremendous throttle response and it ran like a scalded dog!
07-22-2016, 03:35 PM
#53
Melting Slicks
Sig didn't show up last post. I post this then it shows up??????
406", Ported Brodix -10 Heads, 225cc, 2.100"/1.600" valves, 11.8 to 1, Ross Ultralight Pistons, Custom Solid Roller, 650/609 lift 248/252 dur 110 LSA, Comp 1.6 in./1.5 ex. Extreme Gold Rockers, 7/16 Studs, Stud Girdle, Heavily Modified and Ported Victor Jr., Modded 750 Holley, Jet Hot Coated Hooker Super Comp Headers, 3" Mandrel Bent X Pipe Exhaust with 2 Chamber Mufflers, Art Carr 700R4, 3500 stall lock-up, Super Ten 4.11 posi,
406", Ported Brodix -10 Heads, 225cc, 2.100"/1.600" valves, 11.8 to 1, Ross Ultralight Pistons, Custom Solid Roller, 650/609 lift 248/252 dur 110 LSA, Comp 1.6 in./1.5 ex. Extreme Gold Rockers, 7/16 Studs, Stud Girdle, Heavily Modified and Ported Victor Jr., Modded 750 Holley, Jet Hot Coated Hooker Super Comp Headers, 3" Mandrel Bent X Pipe Exhaust with 2 Chamber Mufflers, Art Carr 700R4, 3500 stall lock-up, Super Ten 4.11 posi,
Last edited by v2racing; 07-22-2016 at 03:36 PM.
07-22-2016, 05:16 PM
#54
Melting Slicks
I thought that there was an "ideal" range for squish/quench and being in that range helps with pinging, and that being either OVER (as the L48 and L82s were from the factory) or under increases pinging / premature detonation risk.
I've heard that the "ideal" was a .040" quench, but I realize it's probably not that simple and is probably a range with .040" in the center of the range.
Adam
07-22-2016, 05:22 PM
#55
Melting Slicks
Sig didn't show up last post. I post this then it shows up??????
406", Ported Brodix -10 Heads, 225cc, 2.100"/1.600" valves, 11.8 to 1, Ross Ultralight Pistons, Custom Solid Roller, 650/609 lift 248/252 dur 110 LSA, Comp 1.6 in./1.5 ex. Extreme Gold Rockers, 7/16 Studs, Stud Girdle, Heavily Modified and Ported Victor Jr., Modded 750 Holley, Jet Hot Coated Hooker Super Comp Headers, 3" Mandrel Bent X Pipe Exhaust with 2 Chamber Mufflers, Art Carr 700R4, 3500 stall lock-up, Super Ten 4.11 posi,
406", Ported Brodix -10 Heads, 225cc, 2.100"/1.600" valves, 11.8 to 1, Ross Ultralight Pistons, Custom Solid Roller, 650/609 lift 248/252 dur 110 LSA, Comp 1.6 in./1.5 ex. Extreme Gold Rockers, 7/16 Studs, Stud Girdle, Heavily Modified and Ported Victor Jr., Modded 750 Holley, Jet Hot Coated Hooker Super Comp Headers, 3" Mandrel Bent X Pipe Exhaust with 2 Chamber Mufflers, Art Carr 700R4, 3500 stall lock-up, Super Ten 4.11 posi,
You have a dyno chart posted anywhere? I bet it looks FAN-TAST-IC.
650 intake lift?!?!
Adam
07-22-2016, 05:33 PM
#56
Melting Slicks
I don't have a dyno on the motor in this iteration. It made 560 HP and 530 torque before I hopped it up.
Last edited by v2racing; 07-22-2016 at 05:34 PM.
07-22-2016, 07:04 PM
#57
Le Mans Master
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St. Jude Donor '09-'10-'11
Newbie, mine also has a small quench of 0.036.
V2 that is quite a nice build!
V2 that is quite a nice build!
07-22-2016, 07:38 PM
#58
Melting Slicks
Adam
07-22-2016, 07:48 PM
#59
Le Mans Master
I had no idea. The smallest squish I can get is 0.040" with the FelPro 0.015" gasket. I'd have to have the block decked to go any lower, but with a static CR of 10.2:1 and aluminum heads and my dual snorkel CAI, I think I'd have to do something seriously wrong when selecting a CAM to have this end up being a problem, even with Washington State 91 Octane.
Adam
Adam
07-22-2016, 11:50 PM
#60
Melting Slicks
My L-82 355 with AFR 180 64CC heads, howards roller cam (.525/.525, duration 219/225, LSA 110) JE Forged Racing pistons 9:1 with a total compression of 10.2:1 (Felpro .015) has zero detonation with 89 octane fuel....I also run the dual snorkel L-82 cold air intake with no pinging in any gear, any RPM, any temperature outside.....
-I've been so impressed with the power you managed to get and even the power you got out of your stock, one bad cylinder L82 before you rebuilt the bottom-end and replaced the top-end.
Out of curiosity, what intake are you using?
Adam