cajun wrote:^ Yes but I seriously doubt they accomplished that with a stock bore.

I disagree. RLR built race engines, not sure of the road racing regs but perhaps 1% tolerance overbore is allowed (to take into account oversizes)?

RLR were probably the WORLD leaders in developing the 400cc V4 engine, long after honda stopped racing them, and newer technologies and knowledge on tuning was available.

Their tuning expertise with the nc29 engine was probably not far behind the V4. They used to have full details of their 85hp 400cc V4 on their website (IIRC they even bored out the carbs to flow more air!).

No, you or I probably couldn't build one (or even get one built by RLR!), but an 80hp 400cc RLR nc29 engine is believable to me.

As Tanuki says, the F3 nc23 (and F3 nc30) produced 78hp, this was more than 20 years ago using a hoard of kit engine parts. However, I'm not sure whether this figure is on an engine dyno or at the rear wheel.

I have one RLR Motor engine. It's not overbored unfortunatelly. When fuel injection will be finished - I'll check it potential. But looks very promising. And if I'll get 75bhp - I'll be very happy :))

Anyone ever tried Turbo or supercharging a 400?

I got a RLR motor which makes 74bhp on standard bores, im sure 80 is within reach with some hot cams but i bet it'll be very very peaky.

I dont think its at all unreasonable to believe that 80+ BHP is achievable from a 400cc. It would cost the earth and likely be hugely peaky and unreliable but just look at Moto2 motors for example. These 600cc engine produce around 150BHP naturally aspirated, as a relative comparison shows that 80+ is achievable.

Its all about money and development, the only reason 100+ figures wouldnt be achieved from a 400 is that nobody would be willing to pay to try!

rickee wrote:Anyone ever tried Turbo or supercharging a 400?

I think we need finished with fuel injection before turboring or supercharging ? To be open - I have no such plans.

micklewright wrote:I dont think its at all unreasonable to believe that 80+ BHP is achievable from a 400cc. It would cost the earth and likely be hugely peaky and unreliable but just look at Moto2 motors for example. These 600cc engine produce around 150BHP naturally aspirated, as a relative comparison shows that 80+ is achievable.

Its all about money and development, the only reason 100+ figures wouldnt be achieved from a 400 is that nobody would be willing to pay to try!

Worth considering - pumping and drive train losses will be pretty similar for a 400 or 600cc IL4 engine.

While it'd be great to see, I doubt that a 100hp naturally aspirated 400 is possible, despite the direct power per litre comparison. 80+ sounds plausible, 90+... hmm.

Whos knows! I think if they were at the centre of the development, in terms of competitive sportsbike markets and widespread racing use like 600's have been since the late 90's things would be a little different.

I bet in the days of the 90ish BHP SRAD 600 GSXR the boys in the lab thought 'there's no way we can get this puppy over 100BHP and keep it reliable.'

80+ is possible BDK do it to FZRs

They also do a lot of rebuilds.

100+ I have no doubt could have happened if development had continued, but it didn't so to get 100 out of the 400s we have now I nigh on impossible.

I know of an aborted NC23 turbo project on another forum, I'm thinking of buying a donor Tri Arm and putting a turbo'd 600 lump in it, I think that would be 'fun'. Much in the same way that playing pass the parcel with a live hand grenade is 'fun'!