In RET 110 (May 2018) we published a major Dossier on the NHRA Pro Stock Motorcycle (PSM) V2 produced by S&S Cycle, after its first full season of competition, in 2017. The engine had been produced with the backing of Victory Motorcycles. Matt Smith Racing (MSR) was Victory Motorcycles’ factory team in 2016 but since then, with the brand owner no longer interested in NHRA competition, co-owners Matt and Angie Smith have run their team privately and without full-time helpers.
Angie and Matt Smith – super-successful in Pro Stock Motorcycle (Photo: SR Driven Media)
Nevertheless, racing the S&S engine as a Buell, in recognition of the V2 from which it was derived, since our Dossier was published this naturally aspirated 2.6 litre has powered Matt Smith to three of the four NHRA Championship titles. Wife Angie builds engines and races alongside him, and is likewise a PSM race winner.
Matt Smith on developing the Gen 2
The current V2 from S&S Cycle is now known as the Buell Gen 2. It was preceded by Buell Gen 1 and Gen 1.5, the latter a very restricted upgrade of the Harley-Davidson derived original as produced by S&S Cycle. In effect Gen 2 was a rethink, albeit still restricted by the NHRA homologation process, with the governing body striving to maintain parity with the rival Suzuki I4 and Vance & Hines’ Harley-Davidson V2 engines.
In 2021, Matt Smith won his fifth PSM title following 2007, 2013, 2018 and 2020. He notes that he had a major input into the design changes made by S&S Cycle from Gen 1.5 to Gen 2. He confirms that the engine MSR campaigns now is essentially the same as described in RET 110, although developed extensively within the architecture still manufactured by S&S Cycle.
That development has had to be within the context of what is permitted by the NHRA, stipulations that have not changed fundamentally since 2017. However, one possibility that MSR hasn’t embraced yet is the option of using Sunoco’s Cyclone-17 fuel rather than its established (since 2017) SR-18.
Sunoco SR-18 is a leaded gasoline with an octane rating (MON +RON/2) of 118. Likewise a leaded gasoline, Cyclone-17 has a marginally lower octane rating of 117 but evaporates quicker at lower temperatures and burns faster in the PSM engine. Smith notes that most of his rivals switched to it when first permitted last year, whereas he won the 2021 title using SR-18.
“To switch to Cyclone-17 I would want to lower the compression ratio a bit as it burns faster, and change the cam timing and fit new fuel injectors,” he remarks. “But I have a large inventory of parts suitable for SR-18 and right now new parts can be hard to get.
“Cyclone-17 definitely makes more power – you can get 7-10 more horsepower by just pouring it into the tank. We tried it at the racetrack but it wasn’t so good on the back half of the track so we wouldn’t improve our ETs without making changes to the motor. We are happy with where we’re at right now with our with our motor set-up.
“A lot of people didn’t properly adapt their motor to SR-18 when that came in, and then they see the gain from Cyclone-17 and so they start using that. We figured out how to make the necessary changes to make SR-18 work and we’re sticking with that right now. I guess we will adapt to Cyclone-17 in due course. I have some suitable parts on order but where it used to be 3 or 4 weeks to get stuff, now it’s 12 to 16 weeks.”
In terms of engine dependability, our Dossier reported a bearing issue that had to be overcome in 2017, together with a need to stiffen the con rod. Smith says that once the main bearings were sorted there have been no further issues. “We redesigned the roller mains and we had to make some different inserts to go into the cases. That has eliminated that whole problem since 2017. We are still working with Worldwide Bearings.”
The Buell V2 as campaigned by Matt Smith Racing
In terms of development since 2017, this, Smith reports, has revolved around the cam profiles, porting and combustion chamber shape. AIl his engine work is done in-house, aside from honing the plain iron cylinders, which is done by Elite Performance. “We’ve been working with them for the past 3 or 4 years, strictly for CNC cylinder sleeve honing. That’s proven to be a good partnership – it has really helped our crankcase vacuum and our oil pressure.”
MSR does have a partnership with Denso, which has extended longer than four years. “Denso is a global manufacturer of automotive components offering advanced automotive technologies, systems and products,” Smith says. “This sponsorship includes supplying spark plugs, external starters and other products that have been key components to MSR's success.”
The engine remains at 5.118 in bore and 3.875 in stroke (159.44 cu in) and the bottom end is essentially unchanged since 2017. “We have tried a number of different crankshaft manufacturers over the years but everything seems to be the same thing. We are using Scat cranks these days,” Smith reports.
The con rods and pistons come from CP-Carrillo, and Smith says that working with them there has been development of the piston skirt in terms of its cam (as opposed to barrel) shape. These are billet pistons, and the skirt has Calico dry-film lubricant coating to reduce friction and wear. The crown is uncoated.
The rings are supplied by Total Seal and are what its technical director, Pro Stock (car) racer Matt Hartford considers ideal for this particular engine. “I trust Matt’s expertise,” says Smith. “We have gone thinner on the rings but there is a limit as to how far we can take that due to our bore size and the need for a good ring seal – we can’t go real thin like current Pro Stock V8 rings.”
Each cylinder head is supplied by S&S Cycle without the ports machined. The rules dictate port height, and for logistical reasons the standard 11º splay and 8º cant of each valve is retained – and in any case that was originally specified at the request of MSR. Otherwise the porting and combustion chamber geometry are proprietary, using CNC machining.
The engine is still fitted with titanium valves and triple PSI steel valve springs. “We’ve run the same things since 2017,” confirms Smith. Likewise, the rest of the valvetrain is essentially unchanged. “We would like shorter pushrods but the rule book doesn’t allow that.” Smith notes that various valvetrain coatings have been experimented with but not with any benefit.
We reported in 2017 a standard valve lift of 1.10 in intake and 1.02 in exhaust, although some teams were experimenting with more. Smith says those figures are still appropriate – “I have found that you don’t gain anything from additional lift.”
In 2017 we reported a 2.780 in (70.61 mm) diameter for the intake valve; 2.075 in (52.70 mm) exhaust. Smith reports that the exhaust is now 2.050 in. “We were having a problem with the exhaust clipping the intake valve so we trimmed it down without any loss of performance.”
The two-valve head is twin plug, and the 2017 factory-specification piston crown had valve clearance notches and no intruder yet provided a 14.2:1 compression ratio. Smith says, “We’re still at about that same compression ratio, but we have changed some features of the crown to try to get the flame patterns right, for the best burn. So we’ve taken a bit out of the piston here and added a bit there to improve the burn.”
There is the option of running the two exhausts into a single pipe, but Smith hasn’t found that beneficial. “It was promising on the dyno but it was not better at the racetrack.”
The exhaust and intake geometry are the same regardless of racetrack, with the intake having only a vestigial trumpet feeding the throttle body. Smith says, “I know some people have gone longer with the trumpet. I’ve tried to order some of that stuff but I can’t seem to get anybody to let me have it. They tell me I’m already fast enough, so I really don’t know…!”
The engine is dry sump, and since 2017 a second crankcase scavenge section has been added to the Dailey pump. “We saw that helped down the track; it holds more vacuum compared to using a single pump,” Smith says.
Using an Aeromotive (ex-Waterman) electric pump the fuel pressure remains at about 100 psi (6.9 bar) feeding one injector per cylinder. MSR is still using Magneti Marelli injection, CD ignition and ECU but that is due to be replaced by MaxxECU equipment since it is now an old-spec system for which it has become hard to get spare parts.
“We are still running the same software as we had when we first used it in 2007. Nowadays there is better technology out there!” Smith notes that the engine management system has to be NHRA-approved and that his planned MaxxECU equipment was recently added to the list of options.
Even the software has to be validated by the NHRA, and engine control has to be open loop, the throttle mechanical. Data acquisition is permitted but only for post-run access. “In addition to rpm we monitor the lambda, exhaust gas temperature, engine temperature, oil and fuel pressure and so on including clutch slip, wheel speed and g-forces.”
In 2017 we noted that the key to getting the most out of the motor was to run as close as possible to detonation without actually detonating. We asked: is that still the case? “Yep. You try to run the timing as close as you can, without actually detonating,” Smith says.
How do you monitor how close you are to detonation? “I pull the plugs out after every pass, to read them. We are lucky in that we have that good sponsor in Denso, which provides unlimited plugs. We put new plugs in about every two or three runs, just to help with the plug readings.”
In 2017 we quoted 28º BTDC as representative ignition timing, and Smith says that is still about the mark, using SR-18 fuel. “I guess if you are using Cyclone-17 you will be running a little less timing.”
At the track, what are the key engine set-up parameters? Ignition timing is obviously crucial, what about others? “Fuelling is the other aspect, you have to get that right for the conditions. A lot of times, if you run too lean the bike does not run well; you’re better to be on the rich side.”
And how would you assess the fuelling? “As well as monitoring the plugs I rely on the lambda readings a lot. We have a predetermined number that we’d like to see and we try to get as close to that as we can.”
That predetermined number, is that going to be different for each venue? “Yes, aside from at [high altitude] Denver.”
According to MSR’s engine dyno, at the gearbox output shaft the maximum readings these days are 400 bhp and 235 lb-ft (319 Nm) of torque. “Peak torque is around 8200, 8300 rpm. Peak power is made from around 9300 rpm – it flatlines for about 1000 rpm [with the engine running to over 10,000 rpm].”
Angie Smith on deploying Gen 2
Angie Smith notes that since 2017, MSR has run Matt and herself plus sometimes one or two ‘rental bikes’. “That means a person rents a bike for an event,” she explains. “They don’t have to worry about the stress of running it and about doing research and development and all of that. They fly in, race the bike and then go home again. Some of those programmes have been very successful.
“We expand the team personnel when we are running rental bikes so that we still have one crew person per bike plus what we call a floater, who is someone who goes between all the bikes, helping to tie up loose ends. That helps for example when you’re doing a motor swap between rounds and you have only 15 minutes for it.
Angie Smith prepares for a run (Photo: SR Driven Media)
“When we have just our two bikes we each have a crewperson plus there is usually still a floater. The crewperson does the maintenance of the bike between rounds. Another thing is that every bike we run is pitted exactly the same way, so if someone else comes in to work on it, they’re not in unfamiliar territory.”
Angie reports that back at their shop in North Carolina it is just her and Matt. “It has been like that since 2016, when [Victory brand owner] Polaris decided they no longer wanted to go drag racing, so we had to cut our budget. Back then I was already involved in learning how to put motors together. Fast forward to today and I’m basically assembling motors by myself. Matt and I work together to assemble the bottom end, then I assemble everything else, all the way to the valve covers.
“Matt does our r&d work. A lot of people only do r&d during the offseason but our shop is beside our house and Matt is always working on r&d. He is a workaholic; it is hard for him not to go into the shop 7 days a week, so he’s constantly working on something to make us go faster.
“We do have a cylinder head guy that we fly in when we need work done on our heads, if we need valve jobs or something like that. His name is Trent Townsend; he’s from Oklahoma. Back in the day he learned from Lee Shepherd and some of the other top Pro Stock guys. If we want to try something new with the head then Matt and Trent will collaborate together on that and decide on the direction they want to go in.”
Cylinder head development exploits an in-house Superflow flow bench as well as an in-house Superflow 901 engine dyno. Angie says, “We’re constantly making improvements in the cylinder head department and in the camshaft department. You never stop developing those areas. You never get to a wall where you can’t go any further – there’s always something new coming.”
Angie explains the MSR shop’s set-up. “It is divided into different rooms. There is the bike room where the bikes are kept – the motors are taken out there and rolled through to the engine room.
“The engine room where we rebuild the motors is always kept free of dust and immaculately clean. Then we have a pair of dyno rooms in another section of the shop, one with a Dynojet chassis dyno.
Matt Smith won the 2021 NHRA Pro Stock Motorcycle title (Photo: SR Driven Media)
“Then we have a machine room, including a Serdi to do valve seats, at the back. The hauler sits in there as well – it backs into our shop.”
How many events do you do between rebuilds? “When we first ran the Gen 2 we were taking the motors apart after every race, just to check them,” she says. “But we have made them very reliable. Nowadays we go at least two races and we can go four races without taking them apart. If we reach the finals at an event that is seven laps so we can make up to 28 laps between rebuilds.
“But I’m the kind of the person who likes to put my eyes on things to make sure everything is good. So if we have a one- or two-week break, even if there is nothing wrong I like to take our motors apart just to just check everything. Last year I ran one motor for about 100 laps on the same crankshaft. That’s a testament to good parts and getting everything working well.”
How many motors would you take to an event for two bikes? “We would probably take six spare engines, but hopefully we wouldn’t have to use any of them, just the ones in the bikes. But it’s better to have everything you might need at the racetrack than not.”
If you do a tear-down after two races, what are the key things you’re going to be changing? “If everything looks good, we don't change anything,” replies Angie. “But things that you really have to pay attention to are the rocker arms, the pushrods and the pistons, making sure they’re not cracked and the rings are good. And you have got to make sure the rods and rod bearings are good and that the cranks are rolling well in the cases. Those are the key things you check every time you tear a motor down.”
Which of those items is most frequently changed? “I would say the rod bearings. Sometimes we change them just as a precaution.”
How long would a piston typically last? “I’ve had pistons last 90-100 laps. We’ve really done a lot of r&d on the reliability side. And I think that’s a testament to us winning championships, because it means you can run this stuff on the edge.”
What would you say is the key strength of MSR? “A lot of hard work. I think the foundation is the people we have working with us. We all have the same goal: to win races and championships. I think when you have the manpower and the brainpower and you’re all going in the same direction that is the strongest thing you can have in racing.
“Jonathan Kendrick, Michael Ray and Tommy McDonald are the key people we have at the track. And we know without a shadow of a doubt that when our bikes are at the starting line they are going to be flawless.”
Who is responsible for the set-up of your bike? “Matt is. I do help him; I look at the plugs, and I can read timing. And, you know, we talk back and forth about clutch settings and timing. We bounce ideas off of each other, seeing the data from the computer. But I would say Matt does most of the set-up; I’m probably a very small percentage of it.”
The other side of the Buell V2, as campaigned by Matt Smith Racing
Considering a typical lap, Angie explains that at the start line she will be at wide open throttle in first gear, holding the clutch hand lever, ready to release the clutch at the go signal. “You have to throw the clutch; you don’t try to slip it, it is a 100% release out of the gate. And you use surge, which means you throw all your body weight forward.
“And the shift light comes on quickly, and it does so five times; on a run you shift gear five times.” So it’s wide open throttle all the way? “Yes. Once you’ve thrown that clutch then basically it’s just a matter of changing gear. Of course you have to make sure the bike goes straight; you have to make any steering corrections while you’re shifting. There’s a lot going on in 6 seconds!”
And what’s the rpm when you when you shift? “The shift light comes on at about 9500 rpm, and we shift anywhere from 9500 to 10,000 rpm – I’m not gonna tell you exactly where.” And how much does rpm drop on each shift? “I can’t tell you that either – that would give away our ratios!”
What would you say are the strengths and weaknesses of your motor compared to the current opposition – Vance & Hines’ rebadged Harley V2, the Suzuki two-valve I4 and the Suzuki four-valve I4 introduced last year?
“The four-valve Suzukis are already fast,” replies Angie. “They are generally faster than us to the eighth-mile. They always beat us to 60 ft; they are lighter, at 610 lb. We beat them over the second half of the track but they’re constantly working on their research and development programme.
Matt Smith at the lights (Photo: SR Driven Media)
“I think we’re pretty equal with the Vance & Hines twin, I don’t think we have an edge over them. I think the twins have the most horsepower. But I will say that you can have the most horsepower but you have to be able to put it to the track and you have to be able to manage it. I think Matt does a great job at both, and I believe that he handles pressure situations better than anybody else in our class.”
DATASHEET: GEN 2
60º V2
5.118 x 3.875 in = 159.44 cu in
Naturally aspirated
NHRA-spec gasoline, MON+RON/2 118
Aluminium structure
Ductile iron liners
Three main bearings, ball bearings
Steel crankshaft, one pin
Steel con rods
Light alloy pistons, three rings
Pushrod; gear-driven camshafts
Two valves per cylinder, two plugs
11º valve splay plus 8º cant
2.780 in (70.61 mm) intake valve; 2.075 in (52.70 mm) exhaust
Distributorless ignition
Port injection
Engine management system
14.2:1 compression ratio
Maximum rpm, 10,500
SOME KEY SUPPLIERS
Engine structure: S&S Cycle
Liners (sleeves): Darton
Crankshaft: Scat
Camshafts: Andrews
Timing drive: S&S Cycle
Pushrods: Jesel
Lifters: Jesel
Rockers: Jesel
Pistons: CP-Carrillo
Rings: Total Seal
Piston pins: Precision Products Performance Center
Con rods: CP-Carrillo
Big-end bearings: Mahle Clevite
Main bearings: Worldwide Bearings
Camshaft bearings: Torrington Bearing
Seals: CR
Fasteners: ARP
Valves: Xceldyne
Valve springs: PSI
Valve seats: CHE Precision
Valve guides: CHE Precision
Head gasket: Cometic
Exhaust: Dog Fab
Airbox: Kennys Components
Ignition: Magneti Marelli
Spark plugs: Denso
Fuel injectors: Siemens
Engine management: Magneti Marelli
Data acquisition: Motec
Data acquisition: Racepak
Oil pump: Dailey
Fluid lines: BMRS
Wiring loom: DCE
Fuel: Sunoco
Dynos: Superflow