There’s nothing we love more for big torque and visual impact that a good ol’ antiquated roots supercharger! On episode 25 of Engine Masters
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00:00 On this episode of Engine Masters, a junk small block Chevy, a YN671 supercharger, and a b-b-boost.
00:08 Hey, it's Fryburger here on Engine Masters, where guys like AMSOIL and Mr. Gasket and
00:36 Earl's pay for me and my buddies to hang around and make horsepower, and I love it.
00:40 Especially this episode, where we're gonna make big power with a boost.
00:45 But first, we have to find out what our victim here is gonna make naturally aspirated.
00:49 So here's our combination.
00:51 This is the exact same engine that you saw in the last episode of Engine Masters, although
00:56 we've changed the whole top end.
00:58 The bottom end is just a basic, rebuilt 350 Chevy, just like you might find in, say, an
01:04 '89 Chevy pickup.
01:05 It's cast pistons, regular old cast crankshaft, nothing special.
01:09 However, we did throw a Comp Cam's Magnum hydraulic flat tabbed camshaft in it.
01:16 It's what they call the 280H grind.
01:18 It's a 230 degrees at 50 basic camshaft.
01:21 Now up top, we have added some of my favorite parts, like this carburetor.
01:25 You know how much I love that 850 CFM Ultra XP double pumper from Holley.
01:31 The intake manifold is what I always call the best choice for any street-driven small
01:37 block Chevy.
01:38 It is the Edelbrock Performer RPM Air Gap Dual Plane Intake Manifold.
01:43 These cylinder heads are a Trick Flow Specialties, or TFS.
01:48 They have 195cc inlet runner.
01:51 Now up top, underneath our Mr. Gasket chrome valve cover, we've also added a Comp Cam's
01:56 roller rocker.
01:58 Just their entry level rocker on there.
02:00 It is a 1.6 ratio.
02:02 So normally a small block Chevy has a 1.5 to 1 ratio on the rocker arm.
02:07 That's what they came with stock.
02:08 What the rocker arm ratio does is multiplies the cam lobe lift to give you more lift at
02:13 the valve.
02:15 For example, in this case, with a 1.5 rocker, this camshaft has 480 thousandths lift.
02:20 With this rocker on it, at zero lash with the hydraulic, it makes 512 thousandths.
02:24 And those rocker arms add just a little speck of duration as well.
02:28 So we're going to throw this on the dyno.
02:30 Last time with Vortec heads, just iron heads on it, it made 365 horsepower.
02:35 We're going to find out if our better heads, intake, and carburetor can bump this thing
02:38 over 400, and then go to the glorious YN671 supercharger.
02:43 Let's go check this thing on the dyno right now.
02:46 I'll remind you again that the short block here is bone stock.
02:50 Nothing special about it.
02:51 And that's why the first time we ran it naturally aspirated, Amsoil had us using their OE grade
02:56 oil, which is just sort of a affordable synthetic.
03:00 But they heard we were putting a blower on it, and they said, "We're going to save you
03:02 from yourselves.
03:03 You need to use the Dominator racing oil."
03:06 It's still a 1030.
03:07 The deal is the Dominator has a tougher film strength, so that when we've got boost on
03:13 the thing that's making a lot of power, it doesn't squish that oil out from the contact
03:17 area between the bearing and the connecting rod.
03:19 And so they said, "Use the Dominator stuff."
03:22 Because you, the audience, demanded an actual funnel.
03:27 So I'm going to go there, against my wishes.
03:30 I bet you I can spill this stuff anyway.
03:32 Here we go.
03:40 So we got our engine on the dyno.
03:42 We know it's going to be a lot better than the last episode when we ran the same engine
03:45 with Vortec heads, low rise intake manifold, and a 600 CFM carburetor, and a 1 5/8 inch
03:51 tube header instead of these 1 3/4.
03:53 So it's going to be significantly better.
03:55 We just don't know how much until Uncle Steve fires it up.
03:58 Let's do it.
04:26 Officially not 400 horsepower.
04:28 Pretty close.
04:29 Let's have a look at our baseline peaks.
04:31 We just made 412.4 pound feet of torque at 4,200 RPM, and our horsepower peak was 395
04:39 horsepower at 5,800 RPM.
04:41 Now that's actually pretty good for just a really low buck, 350, until you overlay the
04:46 test that we did on the last episode with the Vortec heads.
04:50 The red one here, when it had a 600 carburetor, lower rise intake manifold, Vortec heads at
04:56 smaller headers.
04:57 And then the black line is what we just did with the TFS heads, the air gap intake, the
05:02 850 carb, and bigger headers.
05:04 And you can see we gave up quite a bit below about 3,800 RPM.
05:08 I think this is not the choice I'd make, but it made a whole lot more power up at the higher
05:12 RPM.
05:13 Just not what I was hoping for.
05:14 I was looking for 420 horsepower.
05:17 So was I.
05:18 Yeah.
05:19 I think we all were, but you know, when you start to look at the difference in those changes,
05:22 it still picked up 30 horsepower.
05:23 The thing I think that this TFS head is really going to give us is a lot more performance
05:28 when you put the blower on.
05:29 Yeah, obviously.
05:30 Now we can use the cylinder head.
05:31 And also you can grow more with that if you wanted to do more mods down the road, like
05:35 higher compression systems, roller cam, and all that stuff.
05:37 A 383 instead of a 350.
05:39 It's still the head that I would buy.
05:41 I would buy that too.
05:42 So here's the real question though.
05:43 We made 395 horsepower.
05:46 Can the 671 make 600 horsepower?
05:49 With enough boost.
05:50 I don't know if we can get there with the pulleys we've got.
05:52 I say yes.
05:54 Cast piston, cast crankshaft, all the wrong things.
05:57 The cast portion of it's not costing any power.
06:00 No it's not.
06:01 It just makes it a time bomb.
06:02 Right?
06:03 Okay, well let's go pull the pin on it.
06:05 All right.
06:06 I like that idea.
06:07 Remember how I said that Edelbrock air gap is my favorite street intake manifold?
06:12 That was wrong.
06:14 The belt driven intake manifold is my favorite.
06:17 That's right.
06:18 The Roots supercharger.
06:20 This thing is awesome.
06:21 Okay, let's go back to the beginning of time.
06:24 These are called Roots superchargers because they were invented by the Roots brothers in
06:28 the 1800s.
06:31 Basically it's a design that uses two rotors that spin together as a positive air displacement
06:37 method.
06:38 They use these things to stoke furnaces, to evacuate fumes out of mines, all sorts of
06:42 stuff like that.
06:43 But since the very early 1900s, they've been used on cars.
06:47 Therefore, this is the oldest supercharging method used on automobiles.
06:52 What it's really famous for though is 70s street machines, but that heritage goes all
06:57 the way back to the early 50s and a guy named Barney Navarro, a legendary hot rodder who's
07:03 recognized as being the first guy to put a Roots supercharger onto a hot rod.
07:09 He used one that came off of a GMC diesel.
07:13 So this is called a 671 blower.
07:16 There are also 371s, 471s, 871s.
07:19 What that refers to is the designation of GMC two-stroke diesel engine that these were
07:24 used on this particular case design and footprint.
07:28 And the 671 like this means this came off a six cylinder with 71 cubic inches per cylinder
07:34 GMC diesel.
07:36 That's kind of the background of where these came from.
07:39 But what they're really known for is 70s street machine goodness.
07:44 These things just look so retro and so cool and they make power.
07:47 Let's just get out of the way all of the things that are terrible about a Roots blower setup.
07:51 They're heavy.
07:52 They have a lot of power loss.
07:54 They make a lot of heat.
07:55 The adiabatic efficiency on them is terrible.
07:58 You got to spend twice as much on carburetors.
08:00 The linkage is a nightmare to set up.
08:02 You got to cut a hole in your hood.
08:03 You can't see around them.
08:04 And the best thing of all is that none of that matters because they look killer and
08:08 they make great power.
08:10 This particular model is a Wyand 671.
08:13 Phil Wyand is another one of the legendary hot rodders and his company has been making
08:17 these things forever.
08:19 It's now a division of Holley.
08:20 They just came out with this case design.
08:23 They used to have the Wyand logo right on the side and they looked a little bit newer
08:26 than this new retro case that they've got.
08:29 They also have a nostalgia drive that you can get.
08:31 Unfortunately they were out of those when we ordered this deal up.
08:35 You can get them as a complete kit for small block Chevys, big block Chevys, and Hemis.
08:39 The Wyand sells 671 and 871 versions.
08:42 This is a six.
08:43 Up top we have two Holley 750 CFM supercharger HP carburetors.
08:50 These things are calibrated specifically for root supercharger applications.
08:56 These things are just awesome on the street.
08:57 The throttle response, the way they fire up, the way they sound, the way they make just
09:02 fat low end torque.
09:04 But my real hope is that this pile of a cast piston small block is going to make 600 horsepower
09:10 and live to tell about it.
09:12 We'll find that out right now as we hook this thing up on that little 350 Chevy.
09:28 You'll see us use this gray RTV in order to seal off the end rails on the intake manifold.
09:34 I wanted to talk a little bit about why because you ever go to the parts store and there's
09:38 all these different colors of RTV and you have no idea what to do?
09:42 Well basically you just need to read the package.
09:43 But here's what Permatex told me about the new Optimum Gray and Optimum Black.
09:48 Basically we're using the gray on all of our old engines except for oil pans where the
09:52 black is better.
09:54 The black is designed kind of for newer engines that have thinner materials and that have
09:59 fewer bolts like on an oil pan.
10:02 It can be used in a thinner application and it's got more flexibility, which you can tell
10:06 because it says high flex.
10:07 So that's kind of for newer engines or for oil pans on older engines.
10:12 Whereas when we're trying to fill a big gap, we're going with the gray stuff.
10:15 Boom!
10:16 See?
10:17 I told you!
10:18 A transformation!
10:19 Right?
10:20 How could I have forgotten that?
10:21 I'm going to have to do it again.
10:22 I'm going to have to do it again.
10:23 I'm going to have to do it again.
10:24 I'm going to have to do it again.
10:25 I'm going to have to do it again.
10:26 I'm going to have to do it again.
10:27 I'm going to have to do it again.
10:28 I'm going to have to do it again.
10:29 I'm going to have to do it again.
10:30 I'm going to have to do it again.
10:31 I'm going to have to do it again.
10:32 I'm going to have to do it again.
10:33 I'm going to have to do it again.
10:34 I'm going to have to do it again.
10:35 I'm going to have to do it again.
10:36 I'm going to have to do it again.
10:37 I'm going to have to do it again.
10:38 I'm going to have to do it again.
10:39 I'm going to have to do it again.
10:40 I'm going to have to do it again.
10:41 I'm going to have to do it again.
10:42 I'm going to have to do it again.
10:43 I'm going to have to do it again.
10:44 I'm going to have to do it again.
10:45 I'm going to have to do it again.
10:46 I'm going to have to do it again.
10:47 I'm going to have to do it again.
10:48 I'm going to have to do it again.
10:49 I'm going to have to do it again.
10:50 I'm going to have to do it again.
10:51 I'm going to have to do it again.
10:52 I'm going to have to do it again.
10:53 I'm going to have to do it again.
10:54 I'm going to have to do it again.
11:22 The deal is that in some situations with a supercharger like this, you could have vacuum
11:27 underneath the carburetors and you could have zero vacuum or maybe even just a hair of boost
11:32 under the blower.
11:34 The engine is wanting more fuel, but because there's vacuum under the carburetors, the
11:38 power valve hasn't opened, and so you're not getting that extra fuel.
11:42 What you do is you run a hose from this port on the back of the manifold up to these ports
11:46 that go to the power valves in all four metering blocks in these carburetors, and then you
11:51 don't have to worry about that happening.
11:53 So that's your deal on boost referenced power valves.
11:59 What we're about to do is put a bunch of boost on a cast piston engine, which is a super
12:02 bad idea.
12:03 We've talked about it amongst ourselves.
12:05 I would never do this in an actual car on something that you cared about.
12:08 It's going to fall apart.
12:09 And we're doing this for, oh yeah, demonstration purposes.
12:13 There you go.
12:14 Demo purposes only.
12:15 Fire up that garbage.
12:22 Oh, almost eight pounds.
12:44 It didn't make any power.
12:47 That's all I was watching was the boost.
12:49 How much?
12:50 Made about eight.
12:51 Yeah, 7.9 at peak.
12:52 It took a while to get there.
12:53 And it made a whopping...
12:54 It made no power.
12:55 Really?
12:56 Nothing.
12:57 What?
12:58 That's a turd.
12:59 So, you know what we need to do now?
13:03 Pulleys?
13:04 Yeah, we need timing.
13:05 No, we don't need pulley.
13:06 We need timing.
13:07 Ooh, yeah.
13:08 Because we've already got eight pounds of boost in it.
13:11 It only made 447 pound feet and 467 horsepower, which is really lame.
13:17 So the timing in this distributor is locked out.
13:20 It has no curve.
13:21 It's always at 25 degrees before top dead center.
13:24 It's a little soft there.
13:26 So we're going to go ahead and probably, what, put two degrees in it?
13:29 Put three?
13:30 Five?
13:31 Steve's actually right.
13:33 I think we'll probably go three the first whack.
13:36 See what it gives us in return.
13:37 What'd you put in?
13:48 28.
13:52 Really?
13:56 I think you put 30 in and he's lying to us.
14:04 So I put 30 in at first and then I backed it down two degrees.
14:07 Really?
14:08 Yeah.
14:09 Okay.
14:10 I wouldn't do that on my own without telling you guys.
14:13 You don't want to blow it up?
14:14 No.
14:15 Well, that was disappointing.
14:16 I thought the timing should have made a much bigger difference than that.
14:29 Once again, so that last pull was 451 pound feet and 472 horsepower.
14:41 What?
14:42 The timing didn't make that big of a difference.
14:44 It normally always does.
14:46 They like timing.
14:47 So what do you think we're running into there?
14:49 Let's put another couple degrees of timing in it just to see if we're kind of in that
14:54 no man's land and now it starts to pick up.
14:56 What number are you looking for?
14:57 Put a 30.
14:58 Okay.
14:59 We'll see.
15:00 If it doesn't respond at 30, then it's just probably not going to respond much.
15:05 That's very surprising.
15:06 It is.
15:07 I really thought that it would have picked up significantly from 25 to 28 degrees.
15:21 Okay.
15:26 Like that.
15:27 That helped quite a bit.
15:29 Okay.
15:30 480 pound feet, 510 horsepower creeping up.
15:34 Still not what we'd like to see.
15:36 Yeah.
15:38 The blue line's where we started.
15:39 Black line's where we are now.
15:40 And that's just with changing ignition timing.
15:44 I think it's telling us what it needs to tell us right now.
15:47 So I think we should look at another pulley combination, see if we can make the thing
15:51 get up to 11.
15:52 540 horsepower would be pretty respectable.
15:53 Cast piston.
15:54 The question you have to ask yourself, do you feel lucky?
16:01 I gots to know.
16:02 Let's get the pulleys.
16:05 I think the short version at this point is we're disappointed.
16:09 I mean, the engine made less than I expected it to naturally aspirated by like 30 numbers.
16:14 And I think it's the same for these guys.
16:16 And hence, it's not doing as well under boost as we would like it to.
16:20 If it had made 420 horsepower to begin with, we would probably be making the 550, which
16:25 is kind of a realistic number.
16:27 Right now, we're looking at just above 500 horsepower, which while it sounds lame when
16:31 you look at this, when you realize that it's a 33% power gain over naturally aspirated,
16:38 and it's a 350 cubic inch engine with a bone stock short block and a hydraulic flat tappet
16:43 cam that's pretty tiny, you start to justify why it's not quite what we hoped it would
16:48 be.
16:50 Okay, making dangerous moves.
16:53 We just flipped the pulleys.
16:54 So the small ones on the top, big ones on the bottom.
16:56 Now we're spinning the blower 11% faster than the engine speed, whereas before it was 10%
17:01 slower.
17:02 So this is going to make more boost and either a big explosion that will put a smile on my
17:06 face or a little bit more power, which might put a grimace on my face.
17:10 We'll see.
17:11 Boom! 528 pound feet of torque at 4700.
17:41 Peak boost, 12.8, and we made 549.3 horsepower, which I feel great about rounding up to 550
17:49 and that happened at 5900 RPM.
17:51 So that took a lot more boost to get to where we needed to be, but that's closer to reality.
17:58 Not that much more though, really.
17:59 You know, going back and looking at some other data and kind of where they were with the
18:03 383s and kind of looking at some other stuff.
18:05 I don't think we're that far off.
18:06 Really?
18:07 I think you ran some numbers though, as far as percentages and that kind of thing.
18:10 Yeah, it's a 40% power gain over naturally aspirated.
18:13 In fact, let's look at this curve versus a naturally aspirated curve.
18:17 Look at that.
18:18 I mean, that tells the story right there.
18:19 That is massive power increase absolutely everywhere.
18:24 Yeah, 110 pound feet of torque.
18:26 I think you'd feel that.
18:27 Yeah, but look at it at the punch down there at the torque converter hit.
18:30 I mean, oh, I know.
18:32 This thing is tire smoke for days.
18:34 So let's ask, how come I'm so negative on it?
18:36 How come was I just had unrealistic expectations of this thing, both NA and boosted?
18:41 Yes.
18:42 Really?
18:43 Really?
18:44 I was just sniffing blue the whole time?
18:45 No, actually I think we all were really close on the NA stuff.
18:47 You know, that's really an interesting point because we were all so afraid and I wonder
18:51 now how afraid should we have been?
18:53 How much boost would this thing take before it breaks?
18:59 Maybe we'll find out next time on Engine Masters.
19:05 What's your spin?
19:07 My spin?
19:08 Yeah.
19:09 Looks great.
19:10 Not quite as much power as I wanted.
19:11 Oh man.
19:12 I thought you had a more positive spin than this.
19:14 I was looking for some uplifting stuff.
19:16 Really?
19:17 Yeah.
19:18 I need to cheer you up?
19:19 Kind of, because you know what it comes down to?
19:20 What?
19:21 It's like roots blower.
19:22 I still love you.
19:24 This guy down here though, not so much.
19:26 I really liked overdriving the pulleys.
19:28 I was kind of disappointed under driving and not using more potential that the blower had
19:32 to give.
19:33 And it's the gift that keeps on giving.
19:35 I have some news for you and for the audience.
19:39 Really?
19:43 Blower gasket.
19:44 Blower gasket?
19:45 Oh no.
19:46 A chunk of blower gasket blew out of the back of the thing between the manifold and the
19:51 blower and we didn't even notice.
19:53 So we had that much of a boost leak.
19:55 It still made the boost that it made.
19:57 I mean the power and the boost are still what they were, but we had to spin the blower harder
20:01 to get it because of the boost leak and that's why we had to go to such a radical pulley.
20:07 So we could have probably made 15 or 16 PSI and even more power.
20:10 Well yeah, we could have either that or we could have scattered the guts of this thing
20:13 all over the floor.
20:14 I will maintain my position.
20:15 The roots blower is the ultimate street intake manifold.
20:19 Nothing gives you that crackly throttle response and torque like one of these things.
20:22 Can I have it?
20:23 No.
20:24 Because once again, I love my blower.
20:27 Okay.
20:28 But once again, I do not love this short block.
20:31 It's just not good and we are going to put a finish to it on the next episode of Engine
20:36 Masters as we answer the question, how much boost can this thing really take?
20:41 Tune in for that next time as we're sponsored by Amsoil, Mr. Gasket, and Earl's Vapor Guard
20:47 hose on Engine Masters.
20:51 You exceed the eutectic point by the Latin prefix hyper, which means greater than.
20:58 We're at hyper-eutectic, which means you have free silicone in the alloy.
21:01 (whooshing)