Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
-
Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.
Highest compression ratio?
- Thread starter 1985xjlaredo
- Start date
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
Whats your combustion chamber cc?
First off, a more reasonable compression with an iron headed small cammed engine is 9.7:1 at the most.
Second, quench really starts to deminish after .045 so I recommend .040 as a target.
I'm building my Father-in-laws stroker with mild porting to help port velocity, diamond pistons for 9.7:1 compression, and a custom 212-216@ .050 cam on 110lca.
We will be dyno'ing the engine on our DTS dyno in Feb. so I will post results. It will have the better intake, TB spacer, and header.
With inline 6's, I treat them like imports...a little here, and a little there makes decent gains in the end.
Brian
Second, quench really starts to deminish after .045 so I recommend .040 as a target.
I'm building my Father-in-laws stroker with mild porting to help port velocity, diamond pistons for 9.7:1 compression, and a custom 212-216@ .050 cam on 110lca.
We will be dyno'ing the engine on our DTS dyno in Feb. so I will post results. It will have the better intake, TB spacer, and header.
With inline 6's, I treat them like imports...a little here, and a little there makes decent gains in the end.
Brian
Gradon,
I used Ford injectors. As I recall they were about 19lb/hr and work well with my MAP electronic gadget to increase injector dwell. The spark plugs were standard Champions, Copper Plus?. Without digging out my detailed notes, I don't recall moving the height location of the pin on the Venolias. The forged flat-top Venolias (no dished top to reduce CR) were spec'ed as follows:
1. Pins offset, like the standard 4.0L piston.
2. Top compression ring groove moved higher up and closer to the top, i.e. a Smokey Yunick recommendation.
3. More holes drilled in oil control ring grooves to allow sufficient oil drain back to crankcase.
4. Ductile iron top compression ring used with standard width. Stainless steel compression rings are now more readily available in 1/16" widths and that would now be a better choice.
Best regards,
CJR
I used Ford injectors. As I recall they were about 19lb/hr and work well with my MAP electronic gadget to increase injector dwell. The spark plugs were standard Champions, Copper Plus?. Without digging out my detailed notes, I don't recall moving the height location of the pin on the Venolias. The forged flat-top Venolias (no dished top to reduce CR) were spec'ed as follows:
1. Pins offset, like the standard 4.0L piston.
2. Top compression ring groove moved higher up and closer to the top, i.e. a Smokey Yunick recommendation.
3. More holes drilled in oil control ring grooves to allow sufficient oil drain back to crankcase.
4. Ductile iron top compression ring used with standard width. Stainless steel compression rings are now more readily available in 1/16" widths and that would now be a better choice.
Best regards,
CJR
Gradon,
I decided to pull my forged flat-top piston card received from Venolia. I did not use standard ring widths. The ring widths were; 1/16", 1/16", 3/16" and the top ring located closer to top (couldn't find the actual dimension but used Smoky's recommendation). I insisted on more holes in the oil ring grooves for better oil drain-back to crankcase and the prevention of low mileage carbon sticking of oil rings. My bore was 3.915", stroke 3.441", pin diameter 0.931"(used lightweight Sealed Power pins). Piston part number was; 6610, Job No. 128691. Rings were Total Seal. Pin holes in piston were offset the standard amount to reduce piston slap noise. I had my local machine shop reduce the pin lengths and install TruArc locking rings, hone the pin holes for free-floating pins, and drill oiling holes for the pins. I used standard rods, polished and shot peened. Engine was balanced.
Best regards,
CJR
I decided to pull my forged flat-top piston card received from Venolia. I did not use standard ring widths. The ring widths were; 1/16", 1/16", 3/16" and the top ring located closer to top (couldn't find the actual dimension but used Smoky's recommendation). I insisted on more holes in the oil ring grooves for better oil drain-back to crankcase and the prevention of low mileage carbon sticking of oil rings. My bore was 3.915", stroke 3.441", pin diameter 0.931"(used lightweight Sealed Power pins). Piston part number was; 6610, Job No. 128691. Rings were Total Seal. Pin holes in piston were offset the standard amount to reduce piston slap noise. I had my local machine shop reduce the pin lengths and install TruArc locking rings, hone the pin holes for free-floating pins, and drill oiling holes for the pins. I used standard rods, polished and shot peened. Engine was balanced.
Best regards,
CJR
- Location
- Desert Beach So Cal
Ed,
Before I started the 4.0L head work, I talked to a AMC racer about how much material was available in the head for milling. In the past, on other engines, I've actually bought cracked heads, band-sawed them lengthwise and sidewise and measured available material for milling.
Using a tracing of the ported combustion chamber and a planimeter to measure area, calculations were then made to estimate how much material had to be milled off my 4.0L head to get 56.5cc. The head was then milled to get 56.5cc. Then initially, the volume of each combustion chamber is measured & marked. Those chambers slightly under 56.5 cc are lightly reground/polished to get closer to 56.5cc. These "massaged" chambers are measured again and the process repeated as many times as necessary until all chambers measure close to 56.5cc. There are many volume measurements made to verify volume measurements or pick up errors in volume measurement.
Best regards,
CJR
Before I started the 4.0L head work, I talked to a AMC racer about how much material was available in the head for milling. In the past, on other engines, I've actually bought cracked heads, band-sawed them lengthwise and sidewise and measured available material for milling.
Using a tracing of the ported combustion chamber and a planimeter to measure area, calculations were then made to estimate how much material had to be milled off my 4.0L head to get 56.5cc. The head was then milled to get 56.5cc. Then initially, the volume of each combustion chamber is measured & marked. Those chambers slightly under 56.5 cc are lightly reground/polished to get closer to 56.5cc. These "massaged" chambers are measured again and the process repeated as many times as necessary until all chambers measure close to 56.5cc. There are many volume measurements made to verify volume measurements or pick up errors in volume measurement.
Best regards,
CJR
5-90
NAXJA Forum User
- Location
- Hammerspace
I wouldn't say the results from reading Taylor are "less favourable" than playing with EA (I've had EA, I have both volumes of Taylor, as well as many other "definitive" works on the four-stroke IC engine,) it really depends on how you learn.
If you have an academic tilt, the books will be just fine - easier to refer to, and you don't have to worry about transferring them to a new computer.
And, having both isn't bad - because you can learn it from the reading and see it in the sim, or see it in the sim and have it explained to you in the books.
I haven't compared the results with EA to the "real world," but engine sim programmes are useful. However, it should be borne in mind that there's really no way to model for all parasitic drag in the real world - when using a more low-buck engine sim (like, say, Desktop Dyno,) figure that real world results are going to be about 5% lower than sim results - the computer simulations can usually be taken to be "optimistic." Just how optimistic depends on what model was used and how many variables were coded into the programme.
That being said, engine simulators are still useful for providing an "apples-to-apples" comparison of various parts swaps - key in all of the baseline data, and play around with cam profiles, for instance. You can still figure out a lot without turning a wrench! Just remember that the results are, indeed, going to be a bit better on the comp than in real life.
I've worked with EAPro - and I'd buy it, if I had enough spare nickels floating around (I need to buy something - upgrading to Win7 64 killed a number of my legacy apps.)
Taylor, Blair, Richardo, et al all do make for some heavy reading - if you're not ready to try to figure out what they're talking about, you may find it too much. Problem is going to be trying to find these books at a library - I bought them because I couldn't find them anywhere around here (and even that took some doing to get them for a more reasonable price on eBay - considering the sort of pricing you'll see from MIT Press or SAE Press...) Bentley Publishing, as I recall, has some good books on IC engine theory - that are a bit closer to layman's terms and cost a good deal less. You may want to peruse their site as well.
@CJR - do you have any pix of your sectioned heads? I want to do something similar with 6-242 heads (I've got a 2685, 2686, and 0630 head so far - need at least one 7120 and 0331. I also want to be able to save a cylinder section for porting experiments...) and I'd like to accumulate as much data as possible.
5-90,
I do not have photos of a sectioned 4.0L head. In the past, I have sectioned Chevy small block heads before extensive porting and polishing. Likewise, I've sectioned a Ford Cortina 4-banger head that, with a Crane specially ground cam and a CR of 12.5:1, Venolia forged pistons, ram-tuned intakes and exhaust (@max. torque) that reved to 8500 rpm (red-lined at 10,000 rpm). Block was the same as used in Lotus Ford Cortinas. Spark was supplied by a custom built Mallory dual-point distributor, a home-built Capacitance Discharge module, and solid conductor Packhard 440 wires. To say that Holley-fed Cortina was a blast to drive, as a daily driver, would be an understatement. With my designed ram-tuned intake/exhaust, the engine was screaming at 6000 rpm, so you could imagine what it sounded like when it reached 8500 rpm. Crane Cams (Steve Edens) was very helpful in suggesting what cam grind to use as well as some lightweight parts for the valve train.
Best regards,
CJR
I do not have photos of a sectioned 4.0L head. In the past, I have sectioned Chevy small block heads before extensive porting and polishing. Likewise, I've sectioned a Ford Cortina 4-banger head that, with a Crane specially ground cam and a CR of 12.5:1, Venolia forged pistons, ram-tuned intakes and exhaust (@max. torque) that reved to 8500 rpm (red-lined at 10,000 rpm). Block was the same as used in Lotus Ford Cortinas. Spark was supplied by a custom built Mallory dual-point distributor, a home-built Capacitance Discharge module, and solid conductor Packhard 440 wires. To say that Holley-fed Cortina was a blast to drive, as a daily driver, would be an understatement. With my designed ram-tuned intake/exhaust, the engine was screaming at 6000 rpm, so you could imagine what it sounded like when it reached 8500 rpm. Crane Cams (Steve Edens) was very helpful in suggesting what cam grind to use as well as some lightweight parts for the valve train.
Best regards,
CJR
