KR cams in an ABF.

Hi all.....again, ok could you help me out? Whats the deal with fitting KR cam shafts into an ABF engine? it seems quite popular...

Philip.

 

dont, no point. ABF cams have better specs than KR ones. The popular swap is for the KR cams into a 9a.

 

ABF INLET & KR EXHAUST is a good one.

 

Thanks boys, sorry for my lack of knoledge but whats the advantage with the KR exhaust cam in the ABF?

Philip

 

Preety much even stevens duration wise, abf has more lift

 

I'd keep the ABF cams - both of them.

 

Yup. Stock ABF Cams work quite well

 

yeah no point in changing tbh

 

on a 9A tho?

 

ABF cams would be good on a 9A too, or a KR inlet is the 'traditional' option.

 

I've tried both these as a test a few years ago. Had then in a stock 1800 bottom end with a flowed head/modified valves.

Yes there's more lift on the ABF cams than the KR, but when in use I found the KR's more agressive due to the sharper opening and closing flanks and longer dwell. Basically the sides of the cam are steeper, opening the valves quicker, then the top of the cam is quite rounded and not pointy like the ABF's, so the valve is open longer at full lift.

The ABF's felt far smoother, and didn't get the 'coming on cam' feel thats associated with the traditional 16v.

 

ive got a 9A and i bought a stealth modified exhaust cam for the inlet side.is this a good option?cheers

 

the 9A came with the 42mm inlet manifold.would it be any good to fit the 50mm manifold i have as well?bit off topic but i appreciate the help.bit new to all the 16v/8v stuff cheers

 

Thats an interesting point Mart - It would be interesting to see the KR and ABF cam profile plots overlaid.

 

Have a search for Toyotec's investigations on different cam options.

 

still no actual RR figures to compare to see what difference there is. ABF cams & KR cams in a 1.8 16v

although i think phil is gonna have a rattle at it in his 1.8 16v for some conclusive proof

 

Hi Mike,
I've read over Toyotecs posts - Kr's are longer duration but less lift. ABF- slightly less duration but greater lift, subtle difference in overlap too. I think more could probably be gleaned from overlaying the profile plot of each set of cams? That's a question mind - not a statement- I know very litte (read as b*gger all about automotive engineering) and I'm looking at this from a simple physics standpoint. I guess the maths gets complicated very quickly when comparing cams with similar duration/lift values but again I guess it comes down to horses for courses and each cam set could be better suited to a particular application?

Edit: Maybe, given the physical properties of the 051/053 castings - perhaps the ABF camset is a more 'refined' desgin whose starting point was the KR cams?

Again though what would be the intention? Performance or drivability.

I'll get my coat as at the end of the day they only way is to model the system and/or perform quantative testing.