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gcarter
05-26-2013, 11:40 AM
In the 550 HP Engine thread, I posted a link to a site with an explanation of BMEP.
That discussion was written by a company called EPI Inc.
They build GM engine conversions for use in aircraft. Very interesting stuff.
Brian 41 was kind enough to post some results of engines he builds. They are very impressive, and he admits they are expensive due to the time and materials invested.
Below is an article about EPI's first effort in aircraft engine development. Due to swinging a very large propeller, and a gear reduction set to accommodate the prop, max crankshaft speed is only 4500 RPM!!!!!!!
Yet this SBC based engine develops 500 HP max and 450 HP @ 4000 RPM. What a great boat engine that would make.


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http://www.epi-eng.com/images/GenInfo/RET-049-135.gifRace Engine Technology Magazine
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Sunday, May 26th, 2013
- EPI Gen-1 Aircraft V8 -Performance, Parts, Development
The Gen-1 Aircraft Engine Program began in 1993, and the first version of the engine was completed in 1996. It was a lightweight, normally-aspirated liquid-cooled V8 with specially-developed top-end and bottom-end components, designed for (a) maximum reliability and (b) excellent performance. It had completely-redundant ignition systems with two spark plugs per cylinder and a specially-developed mechanical fuel injection system.The Gen-1 engine engine was a reliable, liquid-cooled, normally-aspirated aircraft powerplant which produced 500 HP for takeoff (4500 RPM) and 455 HP at max cruise (4000 RPM). It weighed 512 pounds, complete with dual ignition, Bendix-style mechanical fuel injection, fuel pump, dual alternators, vacuum pump, PSRU torsional absorber system and the bulletproof Mark-9 PSRU (http://www.epi-eng.com/gearbox_products/mark-9_gearbox.htm), with prop governor.Driven by cost considerations as well as the engineering need for a better cylinder head design, this powerplant was discontinued in early 2001 and replaced by our Gen-2 (http://www.epi-eng.com/aircraft_engine_products/epi_gen-2_aircraft_engine.htm) engine program.Although this page describes the First Generation EPI aircraft V8 in it's finished form, the actual development process was incremental, with each step forward being based on research and testing of various options and configurations.The Gen-1 engine has been successfully tested for many hours at 4500 RPM (500 HP, max takeoff power) and at 4000 RPM (455 HP, max cruise power). The BSFC is 0.465 at takeoff power and 0.435 at max cruise (91% power). The performance curves are shown in the graph below.http://www.epi-eng.com/images/Engine/epi_gen-1_performance.gifThe following pictures show some of the components used in the Gen-1 engine.Here is a nearly-complete Gen-1 engine, shown without the proprietary-technology intake system and exhaust headers, which are key components in the superior performance of this engine.http://www.epi-eng.com/images/Engine/epi_gen-1_aluminum_V8_engine-2.jpgAn excellent engine must begin with an excellent cylinder block. This block is a GM product, made from high-grade A-356 alloy, heat-treated to the T6 condition. All 5 main bearings have 4-bolt bearing caps made from heat-treated 8620 steel. The block is completely CNC-machined, and is exceptionally accurate when we receive it.Even with such an excellent block, it is necessary to compensate for the imperfections of production machining. We remove all burrs and flashing, and chase all tapped threads. Next is an elaborate cylinder-wall finishing process to assure perfectly-round cylinders, exceptional ring-sealing, and low wear. We then add oil jets which cool the underside of the pistons and meticulously clean all oil passages. Finally, the entire block is cleaned by a special process which ensures the removal of all remaining bits of hone abrasive left embedded in the cylinder walls.http://www.epi-eng.com/images/Engine/smalll_block_aluminum_block.jpgThe next major component is the crankshaft. In order to assure we get the material and processing we specify, we purchase raw forgings, inspect them to verify they are non-twist forgings, inspect them for visual flaws, magnaflux them, and test a sample of the material to verify it is the E-4340 vacuum-arc-remelt we ordered.http://www.epi-eng.com/images/Engine/engine_technology_crankshaft_forging.jpgAfter the forgings pass the incoming inspections, they are sent to one of the country's premier crankshaft manufacturers to be machined to our specifications, providing our engines with the best quality crankshaft available.http://www.epi-eng.com/images/Engine/epi_gen-1_crankshaft.jpgLikewise, our connecting rods are optimized for the load conditions they will bear. They begin as high-quality forgings of E-4340-AQ steel. The profile is machined to provide block and camshaft clearance with the stroke we use, the external surfaces are treated for high fatigue resistance, and the rods are fitted with the strongest stud-fasteners available.http://www.epi-eng.com/images/Engine/epi_gen-1_connecting_rod.jpgThe pistons are very-high-quality parts, optimized for heat tolerance, strength and wear characteristics. They are forged from slices of 2618 extrusions. The tops are finished to assure an optimal combustion chamber configuration, identical on all cylinders. H-11 tool-steel wrist pins are fitted to precise alignment and clearances, and retained with dual spirolox retaining rings.http://www.epi-eng.com/images/Engine/epi_gen-1_piston_pin.jpgAfter many preparatory operations, measurements, trial assemblies and more measurements to verify and assure correct dimensions and clearances, the bottom end is meticulously assembled. Because of the necessity to get precise preload values in the conrod fasteners, we do not rely on torque. Instead, a dial-indicator tool is set up to measure the stretch in the rod bolts and the main bearing cap studs. The nuts are tightened to achieve a specific stretch value, thereby assuring correct and consistent clamping load.http://www.epi-eng.com/images/Engine/small_block_bottom_end.jpgBecause of the original target application for the Phase-1 engine (unlimited aerobatic competition), it used a dry-sump lubrication system, based on a Barnes pump, an EPI pan, and an EPI oil tank which assured uninterrupted oil supply in any orientation. The Barnes pump has an iron pressure-section housing to keep clearances small at operating temperature, with ball bearings on the driving shaft at critical locations. The driven gears in all five sections are aluminum-bronse. The pump was fitted with an EPI redundant HTD toothbelt drive, where each belt has sufficient capacity to drive the pump alone in case one fails.http://www.epi-eng.com/images/Engine/accessories_oil_pump_drive.jpgThe dry sump pan was developed for optimal separation and channeling.(Our later engines use a very sophisticated wet sump system which reduces the windage loss to the same level as the dry-sump, but cuts about 30 pounds off the installed weight and reduces the cost.)http://www.epi-eng.com/images/Engine/epi_gen-1_dry_sump_pan.jpgWell-developed cylinder heads are an essential part of any high-performance engine. Due to the limited availability of custom castings at the time, our Phase 1 cylinder heads were based on an existing casting.That casting used the sub-optimal standard SBC layout, in which each combustion chamber is a mirror-image of its neighbor. That puts the two center-cylinder exhaust ports adjacent to each other, which can cause excessive temperatures and premature material softening in the bridge between those center cylinders. The side-by-side intake ports make the implementation of optimal intake manifolding a challenge. Each combustion chamber has two spark plugs, although neither plug is located in an optimal position.We installed valve seats with optimized configurations and, for that ancient timeframe, optimized materials. We conducted an extensive development program on our computer-data-acquisition flowbench, during which port, valve, seat, and chamber configurations were refined.http://www.epi-eng.com/images/Engine/epi_flowbench_1.jpgWhen the configuration was optimized, we developed a CNC program for the combustion chambers and all the ports. CNC machining assures that all cylinders are identical in flow and burn characteristics.http://www.epi-eng.com/images/Engine/epi_gen-1_dual_plug_head_2.jpgExtensive modifications are necessary to provide adequate head cooling, including the drilling of coolant holes to remove heat from around the spark plug bosses (shown above) and drilling coolant passages to force coolant through the bridge between the center cylinders (shown below), lowering the bridge temperature by a measured 150°F.http://www.epi-eng.com/images/Engine/epi_gen-1_dual_plug_head_1.jpgOur cylinder head castings are machined to nearly-finished form on the 5-axis CNC machining center at the shop of a highly successful NASCAR engine builder for whom we do R&D work.http://www.epi-eng.com/images/Engine/epi_gen-1_5_axis_head_machine.jpgIn addition to excellent cylinder heads, a well-optimized valvetrain is essential to both high output and long life. Using our computerized cam lobe measuring system, we were able to develop cam lobe profiles to work with the cylinder head flow characteristics and provide the tailored torque curve needed to achieve the desired performance.http://www.epi-eng.com/images/Engine/epi_cam_measurement.jpgThe valves, lifters, pushrods, spring retainers and rocker arms were optimized for stiffness, strength and reliability. The dual valve springs were specially developed for optimal reliability. We determined the resonant frequency for both springs needed to avoid the higher amplitude harmonics contained in the cam lobes and to provide a suitable separation from each other. The result was an exceptionally stable and reliable valvetrain.Valve-spring cooling is a significant issue in a long-life engine. If you put a valve spring on a table in a 70°F room and operated it in the same way it is operated in an engine at 4000 RPM, the temperature of that spring will rise dramatically, due to internal friction (hysteresis). In the hot environment of an engine, the problem gets worse. We use specially-developed rocker covers which incorporate an oil-spray nozzle for each valve spring, to assure proper spring cooling.This picture shows the steel shaft-rocker configuration. A common mistake some builders make is to use aluminum rocker arms, probably OK for race cars, but not good for 2000 hours of life.http://www.epi-eng.com/images/Engine/epi_gen-1_rocker_arms.jpgIn order to optimize cooling, we use a coolant pump which can move 100 gallons-per-minute through the engine while consuming only 5 HP. This pump has a redundant drive (visible in the top picture of the assembled engine), so the loss of one of the belts will not cause circulation failure.The coolant flow has been optimized to provide even temperature distributions across the engine. Part of that optimization includes the use of what is known as "4-corner-flow", in which coolant is removed from the front and back of both heads and flows to our bypass thermostat adapter.In order to provide fast warmup without hotspots or local boiling, our thermostat system circulates coolant back to the pump until operating temperature is achieved. At that point, coolant is routed to the heat exchanger and the system maintains coolant temperature throughout the operating range.http://www.epi-eng.com/images/Engine/accessories_thermostat_housing.jpgIn order to eliminate the need for separate external air passages for an oil cooler, we use an oil-to-water heat exchanger to cool the oil. This aids in a fast warmup and the maintenance of optimal oil temperatures under all flight conditions.Although our Gen-1, Phase-2 engines have a purpose-designed, fully integrated accessory drive, our earlier versions used a toothbelt-driven vacuum pump, mounted to our ball-bearing drive unit and driven off the coolant pump pulley.http://www.epi-eng.com/images/Engine/accessories_vacuum_pump_drive.jpgOur redundant ignition system was based on two modified HEI-type distributors, driven by a geared adapter which EPI designed and manufactures. That adapter moves the two distributors out of the way of the special long-runner, X-ram intake system. We chose the HEI style because of its proven insensitivity to static discharge, its very low current draw (in case of electrical problems requiring battery operation in flight) and its very high output in the speed range of this engine. This system is shown below, with one of the distributors removed.http://www.epi-eng.com/images/Engine/epi_gen-1_dual_distributor.jpg
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MOP
05-26-2013, 03:16 PM
Wonder what the cost is? Probably fair considering its reliability and 2000 hour life span.

BUIZILLA
05-26-2013, 04:00 PM
one of my brothers designs and builds all aluminum SB Ford's for aircraft, including his own aircraft he built himself >

www.haaspowerair.com (http://www.haaspowerair.com)

gcarter
05-26-2013, 04:46 PM
That's impressive Jim.
It's one thing to call Sea Tow, but an altogether different thing to fall out of the sky.
Now if only some of these builders would de-content some of their offerings for marine use. Boats don't need dual ignition, dual alternators, or bullet proof gear reduction sets. But it'd be great to have a 450-500 HP small block that could cruise @ 4000 RPM for hours and not worry about it. Then do it again for many seasons.

BUIZILLA
05-26-2013, 07:02 PM
my youngest brother runs 565 engines in both of his dragster's... they took home $5,000 last night for the effort...


https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-frc3/q71/s480x480/292917_10201357840374652_577657165_n.jpg

justleft
05-26-2013, 07:19 PM
Back when I was thinking about building a plane there was a 4 seat version of Burt Rutan's Long EZ
that had a SBC in the rear. Amazing performance ! I don't remember who made the kit.

With the EPI motor it would be insane.

Just Say N20
05-26-2013, 07:53 PM
450 hp is great, but over 550 ft lbs. of torque from 3500 to 4700 rpms, touching 600 ft lbs. at peak! Very impressive.

joseph m. hahnl
05-26-2013, 10:13 PM
I suspect it runs on Meth:doh: .I wonder what the compression ratio is :propeller:

gcarter
05-26-2013, 10:41 PM
It runs on 100LL Av Gas.
No idea on the CR or displacement, but probably about 400 CI.
If you read some of there other articles, they''re pretty talented guys.

duckhunter
05-26-2013, 11:15 PM
That is a sick small block. A lot of engineering in that thing - the redundant systems for aircraft use are really cool. Along with the cylinder heads.

The highest performance engines in my stable are the chainsaws. Jonsered 2152, custom muffler and carb mods, 52cc, 3.6hp, 14,000 rpm. And a Stihl 044 Mag, 70cc, 5.0hp, 12,500 rpm.

woobs
05-27-2013, 07:38 AM
back when I was racing (and the rules were much different) we looked at putting together an effort to do the Daytona 24. The SBC we needed to be even at the fat end of the grid was $35,000! I can't imagine what this aero SBC would cost.

joseph m. hahnl
05-27-2013, 09:11 AM
It runs on 100LL Av Gas.
No idea on the CR or displacement, but probably about 400 CI.
If you read some of there other articles, they''re pretty talented guys.100 Octane ?"LOW LEAD" Gas! ,not going to find that at the marina.:doh: I guess if you think about it. The aviation motor has been at the start of power boat racing. The Liberty V-12 was used extensively in the Gentleman's Racers. Although the EPI motor IS calibrated with a flow bench to peak volumetric efficiency .I think that Air planes being lighter, their wing design,and Variable props , use a much different torque curve to stay aloft then a boat on plane. Don't forget an airplanes fly in the thin air " remember what Ghosts posted". The compression ratio would be through the roof as it is normally aspirated. And you can see in the torque and HP curve on the graph creates almost 600Hp and 550 lbs of torque well before 5250 rpm where torque and horse power meet. Not sure how all that would add up in a boat:confused:

gcarter
05-27-2013, 09:39 AM
Joe, you'd pretend it's a diesel and re-prop for 4500 RPM peak.
As far as fuel is concerned, ask what some of the guys w/blown engines are running.
I would guess w/full aircraft accessories and gear reduction, it''d be $80K, but I'm just guessing.
If someone offered something like this for boats, it might be $45-$50K.

joseph m. hahnl
05-27-2013, 11:50 AM
Joe, you'd pretend it's a diesel and re-prop for 4500 RPM peak.
As far as fuel is concerned, ask what some of the guys w/blown engines are running.
I would guess w/full aircraft accessories and gear reduction, it''d be $80K, but I'm just guessing.
If someone offered something like this for boats, it might be $45-$50K.A blown engine run's +100 High Octane :confused: ? What's up with that :lookaroun::propeller::wink: ? I think that $price$ is a fair assumption

gcarter
05-27-2013, 12:04 PM
Another article that may be of interest follows. We all love the LS7, but the analysis here is whether it would make an aircraft engine.

LS-7 Crate EngineDuring late 2006, we had a new LS-7 engine in our shop for evaluation as a potential aircraft powerplant. This engine represents a new era in factory-crate engines. It is based on the GM Gen-4 LS series, with 427 cubic inches of displacement (4.125 x 4.000) and its own special block, crankshaft, rods, cylinder heads and valves.The block and heads are all-aluminum. The ports and combustion chambers are CNC-machined and provide very high flow numbers. The crankshaft is forged-steel instead of the currently-popular castings. The conrods are titanium.;The 1.8 ratio rocker arms have roller trunnions. The engine has 2.20 inch titanium intake valves, 1.61-inch sodium-filled exhaust valves, a dry-sump oil system, and much more. Techniques which were previously limited to custom engine shops are used in the production of this engine. For example, the final honing on the (special) block is done with deck plates torqued in place and with the main caps installed and torqued. Each engine is assembled by one technician, who signs the worksheets. Each engine is test-run at the GM engine factory before shipping.This engine produces 505 HP at 6300 RPM and 470 lb-ft of torque at 4800 RPM. As pictured (complete) below, it weighs less than 380 pounds! It is probably as close to a race-engine as one will ever see in production. (NOTE the standard, hydroformed, double-wall stainless steel headers).http://www.epi-eng.com/images/Engine/ls7_engine_2.jpghttp://www.epi-eng.com/images/Engine/ls7_engine_3.jpgThe blue lines in the graph below shows the stock LS-7 torque and power curves. Included in this graph are the torque and power curves provided by the 427-CI EPI Gen-1 aircraft engine (red), and initial projections of the EPI-modified aircraft LS-7 (black).These EPI engines are tailored to aircraft operation (sustained high output at max mean piston speed of 3000 fpm (15.2 m/s). As shown in the graph, the stock LS-7 torque curve peak is 475 lb-ft. at 4800 RPM and the power curve peak is 505 HP at 6,300 RPM, at a mean piston speed of 4200 fpm (21.3 m/s). That, like most high-performance automotive engines, is too high for sustained aircraft operation.http://www.epi-eng.com/images/Engine/epi_gen-2_power_torque.gifThe pictures below show some of the high-tech (for production engines) componentry used in the LS-7 engine.This picture shows the roller rockers and the special intake ports used in the LS-7 head. The new LS-7 head design has been rolled over to 12 degrees (LS-2 and 6 are 15°), the intake ports have been raised and reshaped from the familiar "cathedral" shape of the other LS family engines. The LS-7 uses special, 1.8 ratio roller-trunnion rocker arms. The exhaust rocker is in-line, but the center of the pushrod socket in the intake rockers is offset about 0.300" to the right, which tilts the intake pushrod enough to clear the wider intake port. The new intake ports flow in excess of 340 CFM. (For reference, the best of the Gen-1 smallblock heads we developed for our 500 HP engine flowed about 320 CFM while maintaining an excellent velocity profile).http://www.epi-eng.com/images/Engine/ls7_intake_port.jpgThe heads have 2.20-inch titanium intake valves and 1.61-inch, hollow-stem, sodium-filled exhaust valves (for substantially-reduced valvetrain effective mass), beehive valve springs which avoid the problems associated with focused spring resonant frequencies.http://www.epi-eng.com/images/Engine/ls7_valve_springs.jpgThe LS-7 has a forged steel crankshaft (opinion from GM seems to vary as to the material: we have been told both 4140 and 4340 by different sources.)http://www.epi-eng.com/images/Engine/ls7_crankshaft.jpgThis picture shows the forged titanium connecting rods (again, of unspecified material and properties). The pistons are high-grade castings (by Mahle) in an allegedly hypereutectic alloy, and provide the engine with a static compression ratio of 11:1.http://www.epi-eng.com/images/Engine/ls7_rod_piston_2.jpghttp://www.epi-eng.com/images/Engine/ls7_rod_piston_1.jpgThe LS-7 has a dry-sump oiling system with an internal two-stage oil pump (pressure and scavenge) driven off the nose of the crankshaft (same location as the single-stage LS-1&2 pump). The scavenge pump has approximately 1.5 times the capacity of the pressure pump.http://www.epi-eng.com/images/Engine/ls7_oil_pump_1.jpghttp://www.epi-eng.com/images/Engine/ls7_oil_pump_2.jpgFor all the exotic equipment and specifications this engine has, we are somewhat disappointed by the relatively low 11.6 bar BMEP (168 psi) which the stock engine produces. That BMEP is undoubtedly the by-product of the optimizations required for modern automotive applications, including (a) emissions requirements, (b) fuel economy standards, and (c) the astounding wide-range operating response and flexibility which modern engines provide.It is our current opinion that a stock LS-7, in normally-aspirated form, limited to 4500 RPM for takeoff (400 HP at sea level) and 3900 RPM for cruise (330 HP at sea-level), and operated exclusively on a diet of 100-LL avgas, might be used as a reliable aircraft powerplant. That is only an opinion, and there are no test data to back it up.We have been unable to determine the alloy of steel used in the crankshaft. Of greater concern, we have been unable to determine the titanium alloy used in the conrods. BUT, since a set of high-grade, performance titanium rods cost about half as much as the whole LS-7 engine, we cannot help but doubt that this engine contains that quality of conrod, and therefore, we seriously question the use of these rods in an aircraft application, just as we question the use of cast pistons and other production automotive pieces. Note that we could easily carve a sample piece of metal off an LS-7 crank and rod and have the material analyzed in a mass-spectrograph. However, we aren't several-thousand dollars curious, and neither are any of our clients.The reason we think the stock engine should be limited to avgas is that the high 11:1 static compression ratio and sustained full-throttle operation near peak torque will produce very high cylinder pressures which will invite detonation on mogas. The ECU strategy for dealing with detonation is based on the occurrence of transient events, and is handled by removing spark advance until the incipient detonation subsides. That is fine for an automotive transient, but causes EGT to rise dramatically, which is not terribly good for exhaust valve life.In order to provide both normally-aspirated and supercharged versions of an LS-based (see EPI Gen-2 engines (http://www.epi-eng.com/aircraft_engine_products/epi_gen-2_aircraft_engine.htm)) aircraft engine producing in the 500-hp range at a mean piston speed less than 3000 fpm, we determined that several of the internal parts of the LS-7 engine would need to be replaced in order to achieve both the required performance and adequate reliability.Although the LS-7 is a remarkable product, the crate engine is quite expensive (GM factory list price in 2006 was $17,495) and the availability has been somewhat limited. The base cost of the engine, coupled with the limited availability and the extensive modifications needed to transform it into an aircraft powerplant with the performance and reliability we require, make it less interesting as the basis for a 427 CI engine. The same effect can be achieved at a lower cost by purchasing the required components at the beginning, rather than spending a huge sum for a crate engine and then subsequently replacing many of the expensive parts.The Bigger IssueA major issue with these engines is the fact that all the LS engines are electronically controlled by a dedicated computer system (aka Engine Control Unit, or ECU). That system (computer, sensors, injector solenoids, spark coils, and wiring) completely controls the engine's fuel delivery and the spark timing, and a host of other variables as well. Many of the newer engines have "fly-by-wire" throttles (no direct connection between the gas pedal and the butterfly). Although the level of control provided by these systems is remarkable, there remains the problem of reliability, fail-safe operation, and the question of "What do I do when the engine fails (or even hiccups) at when I am 300 feet off the ground on takeoff at Vx ?" CLICK HERE (http://www.epi-eng.com/piston_engine_technology/electronic_engine_controls.htm) for an expanded discussion of electronic engine controls in an aircraft application.
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