Harry Gunusen of American Turbo Power has been forcing engines to produce more power for over 35 years.
In our original story, Harry referred to his friend John Cabral, who originally came to him in 1999. John is a successful businessman who lives and loves turbos.
Harry and John travel all over the country drag racing together with John’s team, with Harry as engine-builder and Crew Chief. The bike is now ridden by veteran rider Augustine Herrera, one of the country’s top drag racers.
At the time of the original story, Harry had built John a 124-inch 2000 Ultra Classic. That bike made 250 horsepower and had won Daytona shootouts many times. It’s a completely loaded down bagger that has run 10-second quarter-miles. It’s a phenomenal bike.
However, apparently that wasn’t enough for John or Harry, and they decided to build a Pro Street (non-wheelie bars) bagger that would go seriously fast. Ultimate Motorcycling sat down with Harry recently and got the full lowdown on the bike.
Harry takes up the story:
Harry Gunusen: “The bike started out as a 2008 Harley Street Glide touring model with bags. Basically it was a 96 cubic-inch Stock Motorcycle that we originally put a turbo kit on as a stock bike. The engine to start with was a 96 cubic inch, which is 1570cc or so, and my good friend and customer John Cabral owned it.
“To start with he wanted to ride it around stock, but after a while we started thinking about going up in size of the motor and making some changes. He was really apprehensive about not going to make it a drag bike. It was just going to be a street bike that’s fast.
“So we did make about 200, maybe 210 horsepower with that. Okay. So after a while he wanted to make changes to the engine, and then all of a sudden he wanted a big cubic inch motor—and of course the bigger the better—at least, that’s what everybody thinks.
“I’ve had customers that we’ve done a motor before with a company called R&R Cycles (rrcycles.com). They make a lot of big cubic-inch motors. So we contacted them and they did us an all-billet 255 cubic-inch motor, which I believe is around 2,600 cc. It has a 4.6-inch bore and 4.5-inch stroke.
“That engine completely replaced the stock Harley one that was in the bike. Naturally then you’ve got to do all the changes to the clutch to increase the pressure, and you’ve gotta do a 3-inch over longer swingarm so it doesn’t wheelie and all that. We struggled a little bit with the fuel injection part of it to get the proper mapping done for a motor that big, and some cam combinations had to be changed.”
Ultimate Motorcycling: What did you use to map the fuel injection? Is it a piggyback, maybe like a Dynojet system or similar?
HG: “Basically, most of the Harley kits that are out there are for the bigger Harley motors. They go to a TTS, or there used to be another company called a Race Tuner which was sold by Screamin’ Eagle. Harley sold that kit as a piggyback system, but TTS became a secondary company that started building maps. So we went to them and made some changes to the cams to accommodate the turbo and everything. We finally got it to work and it made around 320 horsepower…..that was the beginning of it. Then I started looking at it from a weight sense; trying to take some weight off of it.
“It’s run as a stock bagger. There are two rules in the class; it has to have bags, and it has to have the FL style touring frame. You can do body changes like the fairing; you can change that, or you can put a smaller fairing or no fairing, but it has to have bags on it. It’s a class called the Pro Street. You can have a big engine with a turbo, big engine with nitrous, or just a big engine with high compression.
UM: Did you have to change the belt drive? And do you gear it down at all or change anything in the gear box?
HG: “Yeah, you have to go to a chain conversion, a 530 chain. It has a completely billet-made transmission. It’s a 6-speed aftermarket transmission from Baker, and it’s a drag strip version of that. It’s all straight cut gears, these bikes as stock have helical cut gears in 3rd, 4th, 5th, and 6th. But these Baker boxes are completely like a crash box—like Japanese bikes which are all crash box. That means the gears are straight cut and your gear sliders bang into each other. There’s no synchros like in a car—these transmissions shift under load, and going from higher gear ratio into a lower gear ratio, from one to the other, then the dogs that engage they smash into each other. They call that a crash box.
UM: That must be really hard on the metal isn’t it?
HG: “Actually no, crash boxes work really well. The Baker box works really well; it’s a good, powerful transmission. Guys that have gone to high horsepower and they keep the stock 6-speed in them find they keep breaking. So we’ve done this from the beginning. Although despite the kind of power that the bike made, it really wasn’t hard on parts, it didn’t hurt the stock trans, but as a precaution I did it to keep it more bulletproof. The engine itself is an incredible powerplant; it is so bulletproof it’s ridiculous. The engine itself from R&R cycle that we chose to go with–we put probably close to 300 runs on it without doing any bottom-end work, and that includes dyno pulls and hundreds of runs down the track; it did not hurt one bit—underneath the pistons, the rings; nothing.
“I’m talking about a three-year process; periodically, at the end of each year, I’ve had it apart every end of the year for maintenance on it. Nothing was showing any real wear, so we were not really leaning on this thing hard enough to hurt anything. That’s how you gauge it basically in drag racing……you need to turn up the power more and more to see where you’re going to burn a piston or break a ring. Those are your limiting factors. We never reached that; it still has the stock pistons in it that it came with.”
UM: The R&R engine has nothing Harley remaining?
HG: “Nope, nothing. It’s a billet case with their own crankshaft, their own heads, and it has cast-iron cylinders on the outside. They’re not aluminum, they’re iron for stability and for growth so nothing flexes. It keeps the cylinder liner more conformed to the piston. It doesn’t expand; it’s a tighter fitting deal.”
UM: You said you reduced a lot of weight?
HG: “Yes. So, it’s a great combination, that motor, plus I’ve taken two hundred pounds off this bike. The first time we were at a scale at a racetrack, it weighed 870 pounds by itself without a rider. So we started by taking off the floorboards that you put your feet on, those are steel which took over 25 pounds off. I mean you can see on this bike the older bracketry for the floorboards alone are steel, so I went to a regular aluminum foot rest. Every part of the front-end—underneath the headlight, the shielding, and that black cover that goes over that are all steel parts; we removed every piece of those.
“The fairing itself weighs almost 25 pounds. I eliminated the gas tank; put a fuel cell under it and put fiberglass bodywork on that resembled the stock tank; this took off over another 25 pounds. We went to Marvic magnesium wheels; that was another 25 to 30 pounds in the wheels. So last time I weighed it in Maryland it weighs 670 pounds; 200 pounds had come off the bike, and that was a huge change in its performance.”
UM: Do you think there’s more weight that can come off?
HG: “There is more of course, but it’s down to how drastic and more exotic you’re going to get. The fenders that are on there are fiberglass. I can have somebody make me carbon fenders, and go to carbon bags, spend another 3 to 4 thousand dollars in carbon fiber work to save maybe five pounds.
“This class isn’t really that big of a class, this is a challenge that we did just for ourselves. There’s no big win of thousands of dollars at the end of this rainbow, it’s just a claim to fame. You go through this for the love of doing what you’re doing; we’ve accomplished a lot for the class, but there’s really not that much competition. There’s maybe 10 to 15 bikes that show up in the same class, and it may sound like a little bragging, but we go in the 8s, and they can barely get down to 9:20s or 9:30s; that’s a half a second difference. However, the bikes are fast this year, so it’s going to be tougher.
“They’re all catching up and all finally realizing what they have to do. They see us at the racetrack, the bike for what it was before I took the weight off of it. It was going 9:20s, 9:15s, but the last 50 to 60 pounds that came off it put the bike into the 8:60s, 8:70s.
“The weight reduction makes it leave the line harder but also we’ve got a lot of money and time involved in clutch management. We’re still doing some of that now, it’s a centrifugal clutch made by MTC which is engine RPM controlled. It has different stages of springs in it holding it back so that the arms don’t open up immediately. You can stage the action of those spring weights to other spring pressures so that the centrifugal arms come on as you roll down the track. It gives you slippage to be able to leave it in low gear when you don’t have a wheelie bar on when you’ve got to keep it on the ground. These bikes create a tremendous amount of torque, they’re not like a Japanese bike, this engine makes 275 ft/lbs of torque.
“Take a Japanese turbocharged bike, let’s say a 500 horsepower turbocharged Hayabusa will only make 220/230 ft/lbs of torque. This bike is like a tractor – it will pull you off the line really hard and it will wheelie, so you need to keep the gearing correct. One of the things I did was take a lot of weight off the front of the bike, but that made it worse for a while—we were trying to figure out what to do now—and to make it worse we already put a light wheel in the front. Now all of a sudden it’s wheelieing, it’s got no weight in the front.”
UM: So presumably you lower it?
HG: “Yes we did. You’ve got to balance this whole thing.” It has a 17-inch wheel front and rear; I’ve taken all the suspension travel out of it so it sits say… about three inches off the ground. Whereas these things are usually five to six inches off the ground.”
UM: Do you lock-out the suspension?
HG: “The rear has after-market shocks and damping; they have rebound damping on them. So, you need to control the squat when you leave the line and that’s done by those shocks. Harley suspension is not intended for this, these motorcycles were never intended for what we’re doing.
“We need to create some of this stuff, like the clutch right now—we had an air management system made. Until now, we could take some of the weight off the centrifugal controlling arms, so they don’t come on so quickly. We’ve got a system where we add nuts and washers to each arm to create centrifugal force, and we add washers a gram at a time. But we need a lot of weight on the centrifugal arms so it doesn’t slip the clutch on the other end—it (the clutch) isn’t really powerful enough. We’d keep putting more weight on the arms so the clutch doesn’t burn out the other end of the run, but that then made it worse on the starting line. When you let the clutch go, the arms open up too quick, the clutch locks up and the bike wheelies because you got too much arm ratio and so much weight.”
UM: Wow, this sounds hard… not easy to get it right.
HG: Most Japanese bikes run this same clutch with 10 to 12 grams of weight on each arm. This thing has 38 to 40 grams of weight on each arm, otherwise it burns out the clutch. Every time he came back from a run, the clutch had smoke pouring out of it and we had to replace it. So now we have an air cylinder system that applies as he leaves the line, so we don’t need all the weight on the arms.”
UM: …the air cylinder applies?
“You take the weights off and the clutch is going to slip off the line, but the air cylinder starts pushing in; it has a timer and it applies more pressure at the other end. The air cylinder makes the clutch arms come in slower, it pushes into them. It activates a cylinder and adds pressure. It’s a management system.”
UM: Is that your design?
HG: “No, it’s already been done. MTC does this. They make the clutch for it and Japanese bikes use it, but it’s the first time it’s been applied to a Harley. When MTC made this clutch for us they’re scratching their head because they’ve never seen a clutch with that much weight on it and still slip. Well, we’re telling them, this thing makes so much torque, you need something to grab it with. They have a program on their computer which shows how much weight that clutch applies with how much weight you put on it; how much pressure it pushes. We’re exceeding everything they’ve ever seen right now. So now [with the air management system] we’re going backwards… we’re taking weight off so we can leave the line and the bike doesn’t wheelie on us. With the air pressure the timer pushes that cylinder in, which pushes the clutch tighter and tighter so it don’t slip.
“With the air management, you can apply more pressure than you can by putting weights on the arms. But it’s a balancing act with every one of these things. We’re reaching a point where we’re moving so much mass off the starting line, you know, it’s like having the Queen Mary here. With 657 to 700 pounds without a rider on it, it’s a game that you have to play, and make it so it’s smooth and applies properly, so the front wheel comes up only a few inches and doesn’t go straight up.”
UM: What about rear grip, what tires are you running on it?
HG: “Right now we run a Shinko. It’s a drag race compound tire, 190/55, on a big rim, a 6.5-inch Marvic. But there’s a new tire that just came out which we’ve tested on another bike, and it’s the Dunlop Drag Max. It looks like a road race tire but it’s a super soft compound specifically made for drag racing. They’ve already tried them on Pro Street Busas and they’re running in the 6:50s in the ¼ mile. It’s still a 190 mm tire, and they go 230 miles an hour on it.”
UM: Wow – I run 190/55s on my GSX-R1000. You don’t need a bigger tire?
HG: “They don’t go to a 200 tire. They figure the 200 doesn’t give you enough of a flat surface because the 200 has more of a peak to the profile. It’s too wide; the way it fits on the rim it doesn’t give you the right flat surface, so most people run the 190.”
UM: It’s all about profile, certainly in road racing it is too. What tire pressures do you run, what do you run on the back?
HG: “We run about 11 to 12 PSI; most guys run 14 or 15. These tires that Shinko makes they call it a Hook-Up Pro. It’s a sticky compound; it’s a good tire, reasonably priced tire. Dunlop’s more money, but they just came out and the compound’s really good on it, and the casing on the tire is lighter. There’s almost two pounds of rotating mass saved on the Dunlop, over the Shinko and that makes a big difference.”
UM: Do you use rim clamps on the wheels, so that the tire doesn’t spin on the rim?
HG: “No. Dunlop had a thing to start with where they marked the tire and the rim on it to see if there was any spinning going on because of the low pressure. And the new Dunlop showed that the tire slipped almost half an inch on one side to the other when they leave. So they came out with a revised version of it and it’s not doing that anymore. I mean even with that pressure the tire has been holding fine.”
UM: ...and that amount of torque? – going from standstill?
HG: “These Pro Street bikes; like the Suzuki Pro Street turbo bike, they get out there and in second to third gear and they’re all managing the clutch with air. They also change timing in the engine on the computer by taking ignition timing out of it. So they’re keeping the power down till they get into high gear. They put 40 maybe 45 pounds of boost in the motor on the other end to go two hundred and thirty [mph].”
UM: What about the gear changing on it, do you have air shifting?
HG: “It is air operated. There’s a two-step rev limiter on the bike which you use for the launch, so when you pull the clutch in, there’s a microswitch where it goes on to a two-step rev limiter, and so you can set your RPM rev limiter to launch with.”
UM: I thought you were using is centrifugal clutch…so there’s a lever as well that goes with it? How does that work?
HG: “Yes there is. The clutch lever gives you the initial movement, and when you let go there’s a set of springs in the clutch that apply it, but they’re really not strong enough to carry the bike the rest of the way with all that torque. That’s why the arms come in as a secondary. They also do make a different type of clutch for Japanese bikes which is completely centrifugal, it has no clutch lever. But this clutch we’re using they call it a “Gen 2” and it has a lever and it applies an initial pressure of 180 pounds to your clutch when you let go of the lever.”
UM: Moving off the line he still has to find the balance point and drop the clutch?
HG: “There’s not finding anything. You just hold it in—you pull it all the way in, and it goes on the two-step rev limiter. The rev-limiter is set at 3500 or 3700 RPM, and the engine starts missing while you’re sitting there. The minute you let go of the clutch, when the lever moves about [that far], the rev limiter stops, and the engine comes back to life and it accelerates off the line.”
UM: Literally he just sits there then just lets go?
HG: “Yeah, you don’t feed the clutch at all. You just let go, and the absorption of the power is in the clutch; the clutch starts slipping at that point. By you letting go so fast, you’re not going to wheelie, it’s the clutch that’s eating up your power because it’s slipping. And that’s when the clutch arms come in and start making you move forward when they’re locking up.
“Basically, the rev limiter is built into the clutch lever. Now, if you were to turn that rev limiter up to say 4500, it no longer holds back because the clutch is spinning and the arms start pushing. It will fight the clutch out of your hand. It will start pushing your clutch open and you can’t stage; it will make you go through the lights.
“You need to keep the RPM below a certain RPM where your own arms are not going to complain. That’s another point you have to get to, the guy that rides it is Augustine, I watch him when he’s staging. He doesn’t have to hold the bike back and he doesn’t hold the brake lever; the bike has to be able to stage and not creep on him. You do that by turning down the RPM to a point where it’s not dragging the clutch, otherwise, it’s too hard to red light otherwise.”
UM: Your rider’s name is Augustine? Where do you race?
HG: “Augustine Herrera. Most races are on the east coast. Maryland, Georgia, Florida and Pennsylvania. We all have to go out there and it’s a lot of driving for us. We’re racing in a class that’s for Harleys specifically; it’s a Harley bagger specific event.”
UM: With that much power, how do you stay on?
HG: “The seat’s got a cup in it and a hump on the back like a butt stop. You get used to the sensation. It takes a while. You need core body strength and strength in your arms.”
UM: The final drive—do you change anything, change any of the gearing with the final drive?
HG: “We’ve gone from 48/49 rear sprocket down to a 43 now.”
UM: So you go down? What are the final numbers on it? What is your standing quarter now?
HG: “It’s doing an 8.71 in a ¼ mile. I think the terminal was 158.70.”
UM: What kind of boost do you run?
HG: “It has a boost controller; you can set your boost settings in every gear. We progress the boost in each gear; final boost is about 27 pounds.”
UM: Are you running any kind of water injection to cool the thing down at that boost level?
HG: “The fuel we run is straight C16; 116 Octane VP Fuel, and like I said, we’ve never hurt any parts. So I have not done anything like water cooling. I mean, it’s got an air-to-air intercooler so that helps a little bit.”
UM: What oil do you run in it? Anything special?
HG: “We run a straight 50-weight Kendall, and every part comes out of the engine like it was not used. There are no scratches—not even on the pistons. It’s crazy.”
UM: Wow, that’s really impressive. There’s a line from a movie “speed costs; how fast do you want to go?” So in money terms, what would you estimate that this thing cost so far? In other words, if somebody wants to go out and compete in this class…
HG: “It’s crazy, crazy. There’s probably at least a hundred in it …a hundred grand. The engine itself is almost $17,000 by itself without any hardware on it, when you buy it. When you start adding the other clutch systems and the primary chain tensioners and rear wheel sprockets, and the type of wheels it’s got it gets expensive. The transmission itself, it just keeps adding up… And then the electronics; the next thing we’re doing is putting a stand-alone fuel injection on it. The old Harley wiring is coming off.”
UM: What do you think the new fuel injection will do it?
HG: “Probably make it more manageable, that’s the biggest thing we’re looking for, it’s not the power. We can actually control a lot of things like clutch management. You can also include exhaust temperatures. Rear-wheel speed; you’ll get a reading to see if the clutch is slipping or the rear wheel is slipping, you get a lot of feedback from the data acquisition it’s got on it, and we can control timing, that’s the biggest thing.
“We have separate components now for a two-step rev limiter and boost control. All those will be in the ECM that you buy, everything is done in the one unit, it even controls air pressure for the clutch cylinder.”
UM: Wow, that’s really impressive. Is there anything else that you’ve done to it? I assume you have some sort of a quick throttle on it.
HG: “They don’t make one, I’ve been searching for a quick throttle, for a 1-inch throttle, but because of the 1-inch handlebar I haven’t been able to find one. I think somebody has to make one, I’ll find it eventually, but it’s got almost a whole… it’s a big turn. Augustine complained about that for a while, the need to slow the throttle down a little bit.”
UM: Is there anything special with the turbo? What made you go to turbocharging, why not supercharging for instance?
HG: “I’ve always been a turbo person and I built turbo kits for 30 plus years. The turbo market right now has skyrocketed—the performance gains they can do with turbocharging is amazing, without having a belt-driven… well, something that takes power to make power. Turbos are so efficient now. People back in the old days would say ‘oh turbos have lag’ – well there’s no such thing anymore. They spin so freely, they’ve got ball-bearings in them. When he does his burn out he creates 15lbs of boost coming out of a burnout to the starting line. We haven’t even put any load on it yet, and yet we make boost instantly.”
UM: That’s because of the efficiency of the compressor basically?
HG: “Right. For example an old Ray-Jay turbo from the 80s, if you were to spin it by hand it will make one revolution and stop. But you look at a new ball-bearing turbo and give it a touch, it will go three or four turns; it’s freewheeling. They take a lot less oil pressure to run, they don’t fail.”
UM: What do you think will be the next point of weakness?
HG: “We haven’t reached that point; you could almost call it like a slow-burning fuse. It would be the piston, the ring or something in the motor. We haven’t reached anywhere near that by far. It’s got a long way to way to go before we hurt anything. We’ll probably be able to use a little more boost and reach that kind of a horsepower number. But again, that’s really not that important. It’s your starting line, the first 60 to 100 feet is where your ET is increased. The bike will increase top-end without any doubt if it had more power, but you need to be able to leave the line and get the mass moving, that’s the challenge all the time.”
UM: You don’t have any problems with tire grip?
HG: “Yes if you’re at a cold track and the track’s not prepped then yes, that’s a problem. But if we go to a professionally prepped track; like some of these tracks we go to for testing they run VHT. (VHT TrackBite, is a custom formulated resin, typically black in color, used in drag racing to either increase the tire traction or as a sealer for newly ground and/or resurfaced race tracks. It stays sticky for weeks) VHT is a sticky compound all the way to like 800 feet from the line.
“You couldn’t walk on there, your shoes would come off, you’ll fall right over it’s so sticky. They prep them so good for professional cars so when you go test there with bikes you really find out what you can do. I mean they’ve got tremendous traction, it’s comical to watch people—when they walk up to a bike at staging and they’re stuck in their shoes…..now, they’ve got to get out. I see so many people standing there in their socks trying to get their shoe off the ground—but it’s stuck on there, it won’t come off it’s funny. It’s really hot too, that’s not so funny.
“That becomes a factor when you have a lot of power. If you go to a track that’s got no prepping, got no sticky compound, you just spin the tire, so what are you there for? You’re not going to get good results. Cold tracks and some of these streetcar tracks are not the best place to test or to race on. Streetcar tires don’t leave a good sticky compound, and when they make a lot of runs they leave this powdery rubber on the ground and it doesn’t adhere, it doesn’t stick.
“We go to a place—Orlando Speedway in Florida; they do a test session the week before the Gatornationals in March. That track is unbelievable, I mean you look down the track five or six feet… it’s shiny and you cannot walk on it; you cannot walk on it. You take two steps and you’ll be stuck there, it’s that sticky. They have a tractor with a big drum, and a pump with a spray bar behind it; probably six-foot wide. He drives down the track, turns around and comes back, does another 6’ wide, and he does each lane. And after he sprays it another tractor has big giant balloon drag tires in the back of it rolling on wheels, they drag that, they glue it into the ground basically, it’s like you hitting your brakes and skidding on that surface to drag those big drag slicks down the track. And when the sun heats it up, it’s just glue. It’s literally glue.”
UM: How often do they have to do that, the start of the day?
HG: “No, every pro-session on a race day they’ll spray it. And if the pros run, and there’s probably also another 200 other bikes that are street bikes. If they run after that, they have to re-spray it because the tires are ruining that track, putting all sorts of powdery crap on it, so they respray it again. And you’ve got to sit there waiting for it. It’s like a half-hour process to get it sprayed and let it sit and then go to glue; they run over it and they drag it and then come back. And from that point when you first roll on there are strands of glue coming out of your tire.”
UM: So, what’s Augustine Herrera like? Is he a good rider …… is there any speed to be found in him, does he go out and practice, is he a pro guy?
HG: “He’s ridden everything from a dirt bike to small bikes as he grew up, and he’s in his late forties now. His son is 25 and he’s following in identical footsteps to his father. Incredible rider; they’re both incredible riders. His son’s about 30 pounds lighter than his dad – but both of them are the best when it comes to a non-wheelie bar bike. I mean, nothing rattles the ole man when he rides; when he goes to the starting line, he races.
“He’s in race mode and he knows exactly what to do. He’s like a machine when he leaves a line; every time he’s the same. He will stage the same way, he will move his butt the same way, he’ll put his feet in the same spot; he is so meticulous in everything he does. We get along great, he is a very, very good rider. And he’ll come back and tell me what he’s felt on the run, and I’ll tell him what I saw on the run and we’ll figure out what to do. We get along real well on that subject.”
UM: That’s awesome, does he ride anything else as well?
HG: “He rides a Pro Street ‘Busa. Both of them actually, him and his son are on Pro Street ‘Busas. He races less, and he helps his son, they have a business they operate out of the house in Indiana. They do kind of like what I do, building motors and they have their own dyno in the house. The kid has become a whiz now with wiring. He does standalone ignitions and injections.
“Matter of fact, people will send him wiring harnesses off a motorcycle, he’ll rewire it and he’ll send it to you, and then he’ll tune it for you on the phone, through the link. The new systems are like that; when you’re at the track you can hook up to it and he’ll tell you what to do from Indiana while you’re at the track. He’s good at it.”
UM: Who owns this bike, who’s paid for it?
HG: “His name is John Cabral, he’s been a good customer of mine. We became friends, some 20 years now, he’s a turbo nut. He has a business in Tracy up North. He has street sweepers and water trucks for big construction companies and airports, he does city work, got a lot of trucks. His hobby is racing and playing with motorcycles. He’s got probably 20 bikes; I’ve done turbos on just about everything he’s owned.”
UM: That’s awesome, fantastic, thanks Harry.
8-Second Harley Street Glide: Chat with Builder Harry Gunusen Photo Gallery