665 Cubic Inch (10.9 Liters!) Monster Big Block Engine Build w/ Prestige MotorsportsFeb 27, 2020
When you want big horsepower and torque at the touch of the throttle, it's hard to beat
inches and this
enginehas it in abundance. Today we're
building a 665
blockbeast with our friends at Prestige Motorsports in Concord, North Carolina. We missed the short
blockassembly video for this
engine, so I hope you'll excuse me for a few photos while we get started. We don't normally do this, but this engine is so unique that we thought it would still be worth it. The goal of this engine is to create an astonishing amount of power from a naturally aspirated pump gas engine, and Prestige decided to do it with tons of cubic inches.
This specific bill will go toward a high-performance airboat, but the same recipe can produce an incredible tire. toaster in a car or truck, it all starts with a Braddock aluminum block. The Britax Chevy style big blocks have a lot of great features, i.e. they will need the 4 inch 600 mil bore that we will be using, it also has the cam tunnel. a raised deck of four hundred thousand seven inches and a very high deck height of eleven point one inch to allow for a massive five inch stroke to handle all the power we will produce. There are billet steel extended bolt main caps and some very beefy straps on the riser.
More Interesting Facts About,
665 cubic inch 10 9 liters monster big block engine build w prestige motorsports...
Valley plus is all aluminum, so although the tall deck block means this engine will be taller and wider than a standard big block, it will still be lighter than a smaller iron block after the block is machined and engineered. cast aluminum in one of the first modifications. The
prestigeachieved was installing quarter piston gates that pump pressurized oil to the bottom of each piston, helping to keep them cool even during prolonged bursts of full throttle - of course, you can't take full advantage of the nearly 700 cubic inches if it cannot be moved. enough air and fuel in the combustion chambers to keep all those cubic inches fueled properly, which requires a pretty impressive set of cylinder heads and for that task, Prestige chose air and fuel researchers for new 18-degree Magnum cylinder heads because they are Almost the only option that can keep up with the demands of this engine.
AFR's Magnum straightens the valves up to an 18-degree angle compared to a conventional 24 and they combine it with intake ports that have been raised one inch, combine it with two-inch 400 mil diameter intake valves and you get ports which can flow almost 500 CFM making it a higher flow big block cylinder FRS in the chambers and both the intake and exhaust ports are CNC cut and the combustion chambers are sized at 90 CCS. You will notice a spacer bolted to the intake. side of the cylinder head in these photos and we will delve into that later
prestige. The intake and exhaust flanges were CNC cut to accept O-rings and eliminate the need for gaskets.
This is not currently a standard option for AFR cylinder heads, but it is something Prestige did themselves, now let's start with the
build: the crankshaft will have to withstand torque loads applied by combustion of a large amount of air and fuel, for So a Kali's Magnum series crankshaft was chosen and held in place with the bolt shown. main caps, the rest of the rotating assembly is made up of a set of Oliver billet I beam connecting rods and custom je pistons, the rods are 7 inches center to center and that's 865,000 longer than stock, the je pistons are Custom slugs with a significant plate to help keep the compression ratio low, but after running the numbers and realizing how much air the FR heads can float, Prestige decided to go with an even more aggressive Comp Cams cam design. what they originally expected to make everything work.
They needed to hand cut the valve pockets a little deeper here, if you look closely you can see the larger valve pocket cut into the piston on the left side and now that brings us to the point where I really got into the bill. here, lead engine assembler Larry Broker installs ARP head bolts into the block. Head bolts are not as popular on street machines where it can make the heads difficult to remove with the engine still in the car, but that's not a problem on a wide open air boat and bolts are better to maintain a good cylinder seal without distorting the cylinder bores and here is a better view of the pistons and bores.
The dish you see is 233 mils deep with a volume of 44 CCS along with the combustion of 90 CC. cams that maintain low compression at a friendly pump gas ten point four to one the larger valve reliefs that were cut into the top of the pistons are due to the very aggressive solid roller cam from Comp Cams on 50,000 Slithe this cam is ground with 274 degrees of duration for the intakes and 282 for the exhausts with one hundred and ten degrees of separation. Grouse valve lift with 1.7 ratio rockers is 717 thousand for the intakes and 715 for the exhausts at the front, There is no conventional timing chain, instead the Prestige uses a belt.
The Jessel belt drive configuration does a better job of providing consistent valve timing and is more resistant to stretching. In this shot you can see the crank trigger installed and one of the magnets aligned with the trigger. See these custom made spacers at the bottom. The front and rear of the block, these must be bolted into place before the heads and spacers can be fitted. Hang them there. You'll see exactly why in a minute, with the AARP head bolts on the runner, you're ready to lower the F heads into place. The intake spacers, which are about an inch thick, are already bolted securely to the intake side of the heads.
The spacers are necessary because there is currently no cast intake manifold available for an eleven point one inch deck block. A fabricated intake would be an easier option, but it turns out that in an airboat application, vibrations over an extended period of time can cause a sheet of metal to crack, so Prestige had to find a way to make a foundry for a two-story ten-point block work making the elevated entry port. Very practically straight shot to the top of the valve even with the spacer in place. Broker blew the heads 270 foot-pounds in three passes with arp ultra-torque lube on the threads and here's a better shot of the China wall spacers with the heads on.
You can see how they are needed to seal the gap because the spacers create extra length on the intake side of the heads. The valve springs are a double-nested configuration from AFR held in place by titanium retainers. The springs are rated at 240 inch pounds and with maximum lift generating 650 pounds of pressure, now we are ready to move on to the valve train, the Dix bro block is designed to work with tie rod lifters and that is exactly what we are doing here with a set of These solid rollers from BAM tnd were sourced to provide the rocker arms.
This is a shaft mounted rocker system and the racer installs the rocker brackets in the cylinder head. Each bracket is secured to the cylinder head with 12 fasteners that help create a very stable valvetrain. The /16 inch bolts are torqued to sixty pounds each. Pushrods are heavy duty units that flex even at high spring pressures and additional length is required from high deck height. These 7/16 inch diameter push rods are made by 120,000s men. Wall thickness, the intakes are 10 inches long, while the exhausts are longer, 10 inches 700,000 and with the pushrods in place, the rockers can finally be placed on each rocker pivot on its own shaft with two fasteners that fix it to the rocker arm support.
These are aluminum. The t and d rockers and the stock ratio of one, seven to a runner give each a cold whiplash of four thousand with the aluminum block and the heads that should open to a hot whiplash of 20 2004 for the intakes and 24 for the escape. It helps release a little more horsepower. The racer installs a Moroso belt driven vacuum pump which is the vomit tank and breather on the right and here's a look at the FRS valve covers and single plane intake both designed for these 18 heads degrees, the Magnum. The intake fits perfectly into the heads of a standard neck block, but it needed to be modified to work with this specific package and you can see the changes we made at the bottom in this shot, the box in the front is a bifel that It was going to be used for the vacuum pump, but it turned out that the pump was drawing too much oil from this position, so the vacuum ports were moved to the valve covers.
The big change is on the back end, the customer wanted to run a distributor and not individual core packs. So Prestige had to modify the distributor mounting boss because the intake is now too high with the spacers. They did this by cutting the distributor mounting boss off the intake deck, lowering it down, and then welding it back into position. Remember this is a lot. more difficult than it seems because the location of the distributor mounting boss must not only be correct vertically but also laterally as well as fore and aft to ensure proper gear alignment between the distributor gear and the camshaft, If it's not right, it will break.
Here is the final result and although the process took quite a while, everything turned out great and with that we can finally get this ten point nine liter behemoth on the test bench. The carburetor is a Holley Gen3 Ultra Dominator. This is a race. specific card with three circuits and is rated at 1475 CFM, it takes a big carburetor to feed big cubic inches and that's exactly what we have here, plus the Holley sitting on top of a one inch four hole spacer which we started with. Using a set of prestigious Dino headers to lay the foundation of the engine, these heads have a single two and a quarter inch tube feeding a four into one fusion manifold to get in and a bit of tuning, our biggest bully did incredibly well, especially when it comes to producing impressive torque because this motor has an extremely long stroke of 5 inches.
The prestige didn't want to increase the RPM too much like an airboat engine. Peak rpm will be somewhere in the mid-5,000 rpm range, but it will need power. to run there for hours we started pulling at 3500 rpm and it was already making 730 lb-ft of torque at that point and it just went up from its max torque was 910 point 7 at 5,000 rpm and when we cranked the handle again at 6200 rpm it still It made 834 peak horsepower, it was 984 point 5 at 6200 rpm and still going up after that, we made a change to a set of prestige custom heads built especially for this engine, as well as being shaped more suitable for airboats, these Headers are a little larger with two and one-quarter inch primaries and two, two and three-eighths inch steps on the secondary tubes, like the Dino headers, the tubes merge into four collectors into one.
Turns out our 665 was able to make use of the larger headers, the custom headers made significantly more power through the curve up to 5700rpm, peak torque jumped almost sixteen and a half to nine hundred and twenty-seven point one and at 3500rpm it was an incredible power of 50 foot-pounds better. It improved a lot across the range until the dyno heads finally hit 5700rpm. The maximum power of the new heads was reduced by just over 22, the 960 1.6 to 6200 after that we did a final test. Prestige wanted to see if there were more heads. The length would help power production, so 12-inch lengths of pipe were added just above the meltdown.
This time they were not so specific throughout the curve. The torque and horsepower lines of the heads with the extensions almost overlapped the curve of the original heads. max torque was even better with the stock 927 point one two nine twenty one point six heads so we stuck with the heads without the extensions overall this inch big block is an absolute beast no matter if it's on a boat or on a shovel 960 horsepower on pump gas is pretty impressive, but when you can go from 3,500 rpm all the way to 6,200 and never drop below 780 pound-feet of torque, you're talking about an absolute
monsterthat can turn therubber from a tire in fun gray smoke.
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