Hey all, just wondering if i could get some of your predictions.
My mates just had his x-flow rebuilt in his mk1 xr2.

spec is 1680cc bottom end, kent cam (not sure which one it is?) light head work and twin 40's.

We know its not going to be a 150 bhp monster, just wondering what sort of power that setup should make as i know nothing about x-flows!?

cheers chaps!

 

what c/r are you running?if carbs are set it should see 145-150hp,my cousin is dropping an engine off at scs tomorrow to be run-in and dynoed!that should see 145 ish thats got a kent 244,stg 3 head,decked block 1300 pistons and on 38mm bike carbs!

 

no idea what C/R is it, will try and find out off my mate

 

you should get around 140 bhp

 

it has no headwork i have been told.
Its in bits again at the moment as for some reason it had what sounded like piston slap!

 

With nice set up and adjustable igntion should see 145 I would say if not more.
tabetha

 

if u go mental mental the most u can get realistic is 170/80 from a x flow thats stroking it etc etc
iv built a text book build quoting 150 ish thats bore cam lots of head work etc and its prob only making around 100/10 bhp
so look around the 100 to 120 and if its moor it will be a pleasent suprise

 

I highly doubt it will break 140bhp. The cam is a big unknown, it has most probably got a Kent BCF2 or Piper 285 as these don't need valve cutouts in the pistons.

The CR will probably be around 9.5-10:1 than is achieved by using 1.3GT pistons. Although I haven't heard of 1680cc, 90+ thou pistons give 1693cc.

So if it has these mods a small amount of head work, or none, and twin 40's I would realistically say 100-120bhp if properly set up. Check the choke size on the webers, don't be tempted to go any higher than 34mm on that engine.

 

All I know is they are mighty expensive to build right

Here is one I was selling a while back

http://www.turbosport.co.uk/showthread.php?t=143264

 

thank you mate, very helpfull , he is hoping for 110bhpish, so your idea's sound about right.
The engine sback in bits again as it had a bit of a knocking/rattling, turned out to be a faulty little end bearing!
Bit of a pain in the arse, but the engine builder is footing the cost and it should be back together next week.

 

You are welcome Dan,

Jonny, that engine is a cracker but I disagree with you that they are expensive to rebuild. I can easily believe that engine cost £8k+ but if you tune most naturally aspirated engines to double their original power you'll go way above that cost.

If you keep your sights to a realistic 120bhp they are actually good value.

 

As you say it depends what spec you want, like any engine, big power comes at a price and cutting corners usually ends in doing things twice.

Sticking to a sensible spec thats well within its limits of holding together is the best way if your wanting to keep the build and running costs down