Many have theorized that twins are the perfect compromise. Anyone expect to see this engine at 2015 comps?
http://powersports.honda.com/2013/cb...ions/dohc.aspx
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Many have theorized that twins are the perfect compromise. Anyone expect to see this engine at 2015 comps?
http://powersports.honda.com/2013/cb...ions/dohc.aspx
The stock CBR500R apparently makes less than 50 HP, which is less than typical 450cc singles. There are several other parallel twin engines under 600cc in production but they're also pretty weak, which is unfortunate because I suspect that a parallel twin may offer a better power/weight ratio than inline four and single cylinder engines given our displacement restrictions. The Yamaha Phazer is one powerful exception, but it is a snowmobile engine (no gearbox). I don't think there is any technical reason why a powerful parallel twin engine can't be made for a motorcycle, but this graphic from Honda's website leads me to believe the reason they don't exist might be marketing:
Attachment 190
Suzuki revealed a parallel twin motorcycle with a turbo late last year (The Recursion). It's still a concept, but they're advertising 100 HP at 8,000 RPM and 74 ft-pounds at 4,500 RPM. To legally use this engine in FSAE, you would have to replace the turbo with a different turbo.
Many would argue that this is a great thing... ;)Quote:
Originally Posted by Unhealthy_FSAE_Addiction
Agreed, CVTQuote:
Originally Posted by mech5496
I read about this engine a while back, and from what I read the the engine makes exactly 47 hp so that they can meet Europe A2 license regulations. That does not mean that there is not more power to be had in this engine with a little tuning....
The bike is within a few pounds of a 600RR, so it appears that the engine makes almost as much power as a 450 at almost the weight of a 600.
But their also two completely different bikes, as Callen pointed out, the 500R is a new entry level bike to fit the new A2 license. The 500R has a steel frame compared to the aluminium on the 600RR and so on. It's supposed to be a cheap bike both to own and buy for entry level riders.Quote:
Originally Posted by Mbirt
The engine is probably limited by the ECU, I don't see any reason why a skilled team couldn't squeeze more than those claimed 42 horses from it. Usually, teams make more than stock torque from a PC37 as well, just that they're effectively rev-limited by the restrictor...
And btw @JSR: They're, not their ;-)
There's a CBR500R engine for sale on fleabay for only $800. For half the price of a 450 cc thumper, someone should buy it and see what they can squeeze out of it!
With that said, I really don't have hope for it weighing less than 90 lb. According to internet sources, the Ninja 250 (EX-250) weighs about 90 lb, the EX-500 is rumored to be around 115 lb, along with the SV-650 and Ninja 650R (ER-6) in the 115+ lb range. The Rotax 600 ACE weighs 88 lb and it's CVT primary+secondary+belt are an extra 20 lb.
Two questions for the engine experts out there. The cbr500r has a bore/stroke ratio of ~1. The 600cc inline fours and 450 singles which are popular in our series have bore/stroke ratios of over 1.5. The stock redline is 8,500rpm on the cbr500r. Is the low bore/stroke ratio a limiting factor in preventing us from making more power at higher speeds with this engine?
Also. The compression ratio is advertised as 10.7 which is also relatively low. Is this a deal breaker? Does it position the engine for a turbo?
the average piston speed at 8,500 rpm is 18,9 m/s so there should be room for higher rpms.
increasing the compression ratio shouldn't be too difficult considering the relatively large stroke.
It's been interesting seeing the responses. Here are some of my thoughts (Unhealthy_FSAE_Addiction, this may answer your questions):
On their site they specify that this engine has 'the same bore as the CBR600RR'. That phrase combined with the very similar sidecover make me think this engine is built off of the 600RR. I assume that it's 2 cylinders from a 600RR (that puts it down to 300cc) stroked back out to the bore/stroke ratio of 1 (and now we're at 500cc). That's good and bad news. It means 600RR aftermarket pistons will fit, solving the compression ratio problem, and there may be some crossover in the head area (valves, springs, cut a 600RR camshaft in half, etc). The bad news is that the engine will probably not be as light as it could be.
The teams that run singles and go lightweight will most likely see little to no benefit in this engine. But the teams that currently run 4 cylinders might be able to get nearly the power out with a smaller and slightly lighter package. The F4i is ~125 lbs last I checked, I have to imagine that lopping a few cylinders off is good for 20-25 lbs. I know there are a lot of teams concerned about CVTs but twins in general show promise for the competition. This might be the cheap and easy solution to a smaller engine.
We looked briefly at this motor.
From the bit of research done we understood it to be a sleaved 600 twin, so based off that info it was rejected as it would be really tall and heavy. The packaging aspect for our car (very laid down driving position) it would not work as the valve cover would be taller than our harness bar. On top of that it is nearly the same weight as the 4 cylinders.
I wish it was lighter but if I remember correctly it is in the same ballpark as the f4i that we have used for eons.