Jump to content

A very Interesting Read.


veilside z

Recommended Posts

100 BHP per litre? What is it about car engines? I have an old 1996 918 cc Fireblade that makes 130 REAR wheel BHP. (and that on carburetors).

Normally aspirated, ticks over smoothly, etc. And its not a short life but happy one either, this oldy has nearly 60,000 miles up with only one valve shim changed.

The latest litre bikes are pushing 200 BHP.. and are quite happy running around road or track and are Euro 4 compliant.

I can appreciate that cars have to be tuned for torque as much as power if only to shift their body weight, but, surely, someone at Nissan must have looked at motorcycle engine design?

  • Like 1
Link to comment
Share on other sites

Bikes are making 200hp at the wheel largely because they have a much simpler and more efficient drive train, although I am surprised that normally aspirated bikes are up to 200hp at the wheel now, but ive been out of the picture for a while. Of course bike engines don't make the torque though my 180rwhp bike made less than 110ft lbs of torque , a 180hp car engine would probably make twice that and you wouldn't need to rev the nagers off it.

Link to comment
Share on other sites

Just a quick peruse of the figures. The 350z makes around 260 ft.lbs of torque (from 3.5 liters).

Most of the 180 - 200 bhp motorcycles get from 90 - 110 ft.lbs torque.

Multiply the capacities up and.... it would seem that motorcycle make the same amount of torque but stacks more BHP!

I do admit that these (can, safely) rev through 11000 rpm, but, still, what the hell? (And this from just 4 cylinders BTW)

These are normally aspirated, Kawasaki have released a SUPERCHARGED thou, the figures for that are getting on for being unbelievable!

  • Like 1
Link to comment
Share on other sites

Bike engines have 18K rev limits and mad power skills due to short stroke engines, but this is to the detriment of low down torque which a big heavy car needs a lot more.

 

Honda have been making reliable N/A 100hp/litre engines for ages, Im surprised more havent followed but imagine its going to be related to efficiency - high capacity to output ratio invariably means high rev limit as well.

Link to comment
Share on other sites

If a 350z redline was 12k I bet that would make silly bhp, but you have identified the problem yourself, its a lot easier to get some lightweight 250cc pistons reving freely, but chuck in some pistons twice the size and your question is answered, its just physics. A mate had a cbr250 , 19k rpm.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...