Twin Big Blocks Dyno'd Together Part 2

(Frankie)>> You're watching Powernation!

(Frankie)>> Today on Engine Power something we think you've never seen before.

(Pat)>> We run two stroker big blocks on one dyno at the same time. [ Music ]

(Frankie)>> Here in the Engine Power shop we are back on our twin 496 cubic inch big block Chevy build. These engines are being built virtually identical to each other, and so far we've got them to short block status. The plan today is to wrap them up with a bunch of great parts from Summit Racing Equipment, get them in the dyno room, dyno them individually, and see how close they are on power.

(Pat)>> Then comes the hard part. We are going to attempt to couple the engines inline and dyno them on the dyno at the same time, and that creates its own unique set of challenges, but before we get to that here's what has happened on this project so far. We mentioned our double dyno plan to NHRA Funny Car racer Tim Wilkerson. Whether or not he thought our idea was crazy, he was kind enough to spend the day with us setting up bearing clearances. After that we gapped two sets of Total Seal piston rings and installed them on our rod and piston assemblies. Next came a pair of Scat 4.250 stroke crank shafts along with 16 rods and pistons. These are relatively tame engine builds and the specs on the hydraulic roller cam shafts reflect that.

(Frankie)>> Summit Racing Equipment's billet double row timing sets were installed, true t-d-c was set, and the cams were degreed to 103.5, which is 8.5 degrees advanced. We chose a heavy duty cast aluminum timing cover from Summit along with their Pro Pack oil pan kit. It includes a high volume oil pump, pick up, chro-moly driveshaft, and a six-quart oil pan which features a screen, scraper, and one-piece oil pan gasket. Today we'll get started by installing the balancer and timing pointer. Then setting true t-d-c on the balancer. These adjustable timing pointers make it easy to set and lock into place.

(Pat)>> With our head gasket and cylinder head combination we have a calculated compression ratio of 10.27 to one. Thread sealer is required on the ARP fasteners because the bolts go into the water jacket. The bolts are torqued in three steps to 70-pound feet. Next the tie bar style hydraulic roller lifters, which are included in the Howard's cam kit, get lubed and installed.

(Frankie)>> After aligning the supplied guide plates we put thread sealant on the Trick Flow rocker studs. Sealant is required because the studs intrude into the intake port. Our Trick Flow push rods are three-eighths in diameter and have an 80 thousandths wall. They are 8.800 long on the exhaust and 7.900 long on the intake side. High pressure lube goes on both ends. Then they are slid into place. For rockers we're using Trick Flow's full roller aluminum design with a 1.7 ratio. Because we're running a hydraulic roller cam shaft, pre-load is set to one half turn past zero lash.

(Pat)>> With r-t-v laid around the coolant ports and on the China walls, the intake manifold goes into position. The ARP stainless steel intake bolt kit receives thread sealant because some of the bolts intrude into the lifter valley, which could cause oil leaks.

(Frankie)>> With the valvetrain lubricated they are covered with a set of polished cast aluminum valve covers from Summit Racing. [ Music ] Summit Racing's polished aluminum electric water pump will handle the cooling. Our induction is finished off with a Trick Flow one inch tapered four-hole spacer and a QFT 1,050 c-f-m annular discharge carburetor. Up next, in theory two identical engines should make the same numbers on the dyno.

(Pat)>> Well there's theory and then there's practice.

(Pat)>> Before we dyno the two big blocks together we need to dyno each of them separately to see how much power they make. Slick! First up is what we consider Engine "A". It was primarily built by Frankie. So, he gets to run the controls. After our standard timing and fuel adjustments we'll make a final run. [ engine starting ]

(Pat)>> These engines are gonna be all done before 6,000 by design.

(Frankie)>> We didn't want something that's gonna turn 6,500, 7,000 r-p-m because theoretically when we're done we have two of them. So, whatever they make should double. [ engine revving ]

(Pat)>> Wow, wow, wow! That was very torquey!

(Frankie)>> 629 for torque and 596.7. 596.7 is at 5,500, peak torque is at 4,500.

(Pat)>> Now you can see it's trending down, right? People always want to run these things way past where they're making power. There's literally no reason for this. If this thing is trending down because of the size of the intake tract, because of the size of that cam shaft. This thing is designed to be literally done by 6,000.

(Frankie)>> With a cam shaft, 236, 242, that's the same cam shaft we put in a 410-inch Mopar, and now we have it in a 496 big block Chevy. Torque 1.27 per inch, power 1.20. I mean that's good for the size cam, size intake, heads, all that. So now the question is gotta get Engine "B" on and see if it makes the same.

(Pat)>> So we made 596.7. If "B" makes 620 something's going on. Engines are gonna be relatively close because they are the same parts. We guessed that they'll be within 10 or 15, but if it crests that 20 mark anywhere either one engine's bad and one engine's good or whatever. So, let's see what Engine "B" does. [ Music ]

(Frankie)>> The change from Engine "A" to Engine "B" was quick because they are essentially the exact same power plant. We'll put the same tune up from our previous dyno run into Engine "B".

(Pat)>> Because humans worked on this right, there's gonna be subtleties and all kinds of different things. From the carburetor to the oil pan, everything in between. Plus, the goofballs who clicked them together. So same exact pull. It's like we never took the other engine off.

(Frankie)>> You wouldn't be able to tell just by looking at it. [ engine revving ] [ Music ]

(Pat)>> That's close right there my friend. 632.7-pound feet of torque, 607 horsepower. Two completely different engines, almost the same result to a very, very small degree. You know what I call that? Deja-vroom! I can't believe I actually said that, but it's the truth, right?

(Frankie)>> It's worse than the dad jokes.

(Pat)>> That is a horrible joke and I admit that, but it kind fits it because we've done two completely different things. You screwed one together, I screwed one together. "B" team did make a little more power.

(Frankie)>> There's some other stuff going on maybe.

(Pat)>> Maybe, no I didn't.

(Frankie)>> Obviously there's some subtle differences going on inside the engine.

(Pat)>> They weren't exactly identical on compression. There were subtle differences. How the manifold was cast, who put the boosters in the carburetor, at what height. There's a whole bunch of different stuff, but what I can say is we have engines that are very, very close. Happy times!

(Frankie)>> So now we move on to the hard part. Up next, to make two engines run together on the dyno it's gonna take a lot of planning, a bunch of work, and probably a little luck. Maybe this isn't such a good idea?

(Pat)>> Alright I have to admit. I am impressed on how close they made the power.

(Frankie)>> Being that close with the same selection of parts, less than two percent difference. I think that's kinda cool. We could fuzz them and get them closer if we wanted to, but I think for what we're doing that's gonna be just fine, and now we have to move on to hooking them together, which I kinda have an idea on how to hook the cranks together, but there's a bunch of other stuff that goes with that. Water, fuel, power, all that stuff.

(Pat)>> We can pontificate about it all we want out here. Let's just roll it in, get it close.

(Frankie)>> Start mocking it up and see what we need to do. We've already got Engine "B" on the dyno. Engine "A" will be installed in front. [ saw buzzing ]

(Pat)>> We'll begin with the easy task, splitting the water lines on the top and bottom. To do that we'll use some one and a half inch o-d tubing to make a couple of simple T-joints. The joint is welded together, and a hole is opened up for the water to pass through.

(Frankie)>> The next plumbing we'll tackle is the exhaust. In order to effectively evacuate it from the dyno room we'll fab up a system that joins both engines into a five-inch outlet. After the exhaust is test fitted it can be finish welded. While we work on that Jimmy King from the Carcass shop cut out both of our drive plates on his c-n-c plasma table. These will bolt to the balancer and the flywheel and are made from quarter inch mild steel.

(Pat)>> Next, the hub for the flywheel side of the drive system is mad from half of a mini spool for a Ford 8.8-inch axle. We machined a register in it so it would fit precisely into the center of our flywheel drive plate. This ensures that the plate is completely flush when the two pieces are tacked together. Since the drive assembly will endure extreme abuse, it is welded on both sides. [ drill humming ]

(Pat)>> Now we need to determine the right length for the axle shaft that will connect the two engines together. Drive plate to drive plate. So, if the end of it's there and that is flush, that is right on nine and a half. We'll cut 10.5 inches from the Summit Racing 31 spline axle shaft. Then back to the lathe to put a register on the axle so it fits into the drive plate. [ Music ]

(Frankie)>> Before we can tack the axle to the balancer drive plate, we're going to make sure that both engines are at t-d-c compression stroke on the number one cylinder. [ Music ] With the bolt holes aligned and the bolts snugged down, we'll mark and scribe both pieces to ensure correct alignment. Then the piece can be tacked and fully welded on both sides in the lathe. To mount the two carts together we're going to keep things simple. Half inch holes are drilled in the rear cart, and the splines are splathered with extreme pressure lube. We fabbed up two spacers out of 60-61 aluminum. They slide onto a set of half inch grade eight threaded rod, and the two engines are carefully mated together. [ Music ]

(Pat)>> Okay! [ metal clanging ] [ Music ]

(Pat)>> Next the coupling system is indicated across three planes to make sure that everything is in precise alignment. Both fuel logs are connected with a number eight Earl's line. A rod with heims connects both carburetors. Using our hand made T-joints the front engine is tied into the water system and everything is sealed up. This is the custom of the custom right here.

(Frankie)>> It's funny cause it looks like a diesel exhaust but it's really for two big block Chevys. [ drill humming ]

(Pat)>> Up next, it's death or glory as we fire up the twin big blocks.

(Frankie)>> Okay, so this is about the point where you start to think maybe this isn't such a good idea, maybe we're insane.

(Pat)>> I still think it's a good idea because we haven't done anything yet. The one thing that this is probably gonna protest is the start.

(Frankie)>> Yes because you have twice the cubic inches, and these are pretty stack on dynamic compression, and it's still one standard big block Ford starter.

(Pat)>> Well no time like the present. [ engines cranking ]

(Pat)>> Get some fuel through her. I was kinda hunching there for a second.

(Frankie)>> But they're both running!

(Pat)>> That's two engines running.

(Frankie)>> That's smooth too. Not shaking, not moving, anything like that. We've got a nice, rigid mount.

(Pat)>> We'll see what a partial throttle pull does. Then maybe we'll go to half throttle. Just make sure nothing's on fire. [ engines revving ] [ Music ]

(Frankie)>> It did it. I didn't see anything.

(Pat)>> That's fine. That was probably quarter throttle right.

(Frankie)>> 628-pound feet.

(Pat)>> 311 horsepower! Obviously, we know what the engines make.

(Frankie)>> Nothing looked crazy, the engines didn't move around a ton. They're nice and solid. No parts came out, nothing's leaking.

(Pat)>> It's a rarity that a dyno run gets my heart racing, but this one actually is.

(Frankie)>> You're just waiting. Waiting for something bad to happen and hoping it doesn't.

(Pat)>> I'm gonna go half throttle.

(Frankie)>> Go half and we'll see what it does there.

(Pat)>> Hold on to something! [ engines revving ]

(Frankie)>> It still looked good.

(Pat)>> It broke 1,000-pound feet. [ Music ] That's half throttle. 1,017 for pound feet at 3,600. Again, that's half throttle.

(Frankie)>> Yeah manifold vacuum, and we're only monitoring on the second engine, but manifold vacuum is going up to like four inches.

(Pat)>> They're gonna be the same.

(Frankie)>> Yeah but four inches.

(Pat)>> When I saw that thing crest 1,000-pound feet I about jumped out of my seat.

(Frankie)>> I was looking in there, but nothing looked crazy. Again smooth, the engine stayed.

(Pat)>> It's time for the big megambo! What do you think?

(Frankie)>> You think we should check anything first or just go for it?

(Pat)>> Go look at that shaft, make sure everything's okay.

(Frankie)>> Just double check everything.

(Pat)>> Woo doggy!

(Frankie)>> If anything is likely to fail it's our drive system. So, we'll give it a quick visual inspection and check all of the fasteners. So far looks good.

(Tommy)>> How far you gonna wring this thing out?

(Pat)>> We are gonna now do a pull like there was only one engine. So just like we did before, 3,000 to 5,800.

(Jeremy)>> But they're hooked together.

(Pat)>> This is literally the first time we're doing a wide-open throttle pull. This could go super bad or super good. We have zero idea.

(Joel)>> You guys got a helmet?

(Frankie)>> This is full on, I'm nervous. I'm sketched out and nervous at the same time because...

(Tommy)>> What about you two, y'all nervous?

(Jeremy)>> I'm not.

(Pat)>> 3,000 to 5,800, you alright? You're actually freaking out right now.

(Frankie)>> I'm ready to dive in there, I guess. I'll watch for parts and flames. You watch that I guess.

(Jeremy)>> No time like the present. [ engine revving ]

(Carcass)>> It did it! I was watching the r-p-m too.

(Pat)>> That is not bad, 1,212-pound feet, 1,162. Mathematically it should double the engine but again, we have two different things going on here.

(Tommy)>> So you're gonna find where you lost that horsepower right?

(Jeremy)>> Somewhere, two options.

(Pat)>> I am rarely nervous during a dyno pull. I'm like oh my god, what's gonna happen right here.

(Tommy)>> I think it's worth another pull. Y'all don't build things to break'em. It's not gonna break!

(Pat)>> The engines are fine. The drive system is what we're worried about.

(Tommy)>> To actually set a record you have to do one pass and then you've got to follow it up.

(Jeremy)>> One can be a fluke and two is proof?

(Pat)>> I can't believe that worked.

(Tommy)>> Hold on, both of y'all stick your fingers out right now. You're kinda shaky.

(Frankie)>> Anybody who's been watching the show knows that I'm shaky anyways. You should see me weld. It's like this. [ engine revving ]

(Jeremy)>> It doesn't even care.

(Pat)>> 1,204, 1,167.

(Joel)>> Not practical by any stretch but that's cool!

(Pat)>> Alright guys, you saw it live!

(Jeremy)>> It's like a first! There you go!

(Pat)>> Looking at peak values Engine "A" made 596.7 horsepower and 629-pound feet of torque. Engine "B" made 607.5 horsepower and 632.7-pound feet of torque. Adding those numbers together we get 1,204.2 horsepower and 1,261.7-pound feet of torque.

(Frankie)>> Taking our highest peak numbers from our double dyno runs we made 1,167.1 horsepower and 1,212.2-pound feet of torque. When we subtract our combined single dyno results that puts us down 37.1 horsepower and 49.5-pound feet of torque from our ideal expected result. Still, it's almost a pure doubling of power and torque compared to the single engine runs. We're only down 3 percent on horsepower and 4 percent on torque. We're not certain why yet, but we expect that the combined exhaust and perhaps engine phasing could be big factors. That just goes to show it's not about what engine you have. It's about how many you have.

(Pat)>> Some people like power adders. I'm an n/a guy right. So, some people like turbo, some people like nitrous, some people like blowers. I just like adding another engine.

(Frankie)>> It's just more cubic inches.

(Pat)>> That's the ultimate power adder, another engine.

(Frankie)>> That is great success.

(Pat)>> To learn more about this build go check out Powernation TV dot com.