Oettinger, Graf, KR and ABF heads - How much do they flow?

I've got an early KR head on mine which has a narrower port divider so the inlet side is alot better but the exhaust is a bit worse. My engine builder has experences with both KR head types and said the early type is defintly better.

Port work on my head isint the best and could do with a tuned length exhaust manifold. I've lowered the coolant temprature 20 degrees, and enlarged the breather hose since it was on the rollers where it made just over 200bhp (genuine race engine builders rr not some Lax Power specialist) and power's still not peaked at the 7800rpm revlimit.

I'm confident that with the little mods i've made since and some steel rods to allow a higher revlimit it would make in the region of 220bhp out of a 1800. So I think 250 is acheiveable on a KR head without too much trouble.

I also know of a standard KR head ported by the man in the shed that was just a Pack A with ballanced chambers and 28mm exhaust seats (standard valves are 28mmm but with a restrictive 27mm seat) This made 240bhp on a 2000 16v.

I would recomend trying to get hold of an early 16v head or a 20V head and I think that power output will be down to engine component selection and mapping then.

 

So, early (how early is early?) KR heads are better? Are they superior to ABF heads too?

 

What size bodies should I be looking at for an output around 250? 45, 48, 50? What will be the advantages / disadvantages of a larger diameter?

 

I doubt it...the exhaust side seems much better on the ABF

When fully ported and modified, will it really matter which bare casting you choose?
I doubt it.

 

bigger the body, lower the port velocity so a trade off in torque curve and top end usually.
in these spec high motors high Cr, fruity cams, they can tolerate more than a stock cr motor cam wise.

 

Personally I would tend to go for a 48, if you are looking at second hand stuff then just go for what you can find at the right price anything 45's and up shouldnt be a problem

Mine is on tapered bodies tapering from 48 down to about 42 and ther's no sign they are restricting it

 

I think I am going to spark off the age old debate here but....

What about doing an 8v project, my old engine was 194bhp with a completely standard bottom end and nothing too radical...i.e. 288 cam, twin 45 DCOE's and an off the shelf head from TSR.

I dont think you would get to the desired 250bhp...but built to the same spec it would be an awesome motor.

Just seems to suit the ethos of the project aswell...

Or an alternative would be to buy a 16v car that I looked at before christmas that has run 200bhp at the wheels so would be circa 240bhp...its up for 10k I think and has a Gemini 6 speed gearbox.

 

^^ and it came 10th o/all on a stage rally just a couple of weekends ago.

45s have to be the way to go, unless you're into daft cheque writing and can genuinly say it's affordable. They're available, cost effective etc.

I've got a 200+ bhp 16V in Ian's ^^ old motor and whilst I could faff incessantly with 48s or whatever, I literally cannot be bothered. It's just after after , though I appreciate some can get this done for cheap. From what I've seen on other 16V engines it will doubtless drop torque anyway.

 

258BHP 2L 16V for sale on Berg Cup site right now. Gives nice detailed spec to. Worth a read. No price though.

 

I can't find this, do you have the link? Thanks.

 

I'm with Ian on the 8v...

But if 16v is what you want then theres nothing wrong with that.

If it's being built as a fun thing/track day toy then build it to yr budget rather than try to chase a power figure, and factor in as much reliability as you can.

A competitor in the hillclimb series I run in used to have a "very" quick 205 with a 230hp Mi16, he once said "how the f$%k you would need more than around 230hp in a fwd car I'll never know". He's had FTD (fastest time of day) against single seaters in that car so knows a thing or two about fwd, and I've handed him timing tickets with his hands trembling after a run... if 230hp gives that kind of buzz...

If you can "only" achieve 220-230 hp, I doubt you'll be upset by the way it goes.

Either way, 45mm bodies will give a better power spread and not lack that much at peak. Remember, you only hit the peak number once before each gear change, you have to pull "through" the rest of the power curve to get there.

 

16v all the way i'm afraid!! :-) So we have managed to conclude that this will cost me 10k + and that a std head will probably yield similar power to an Oettinger / Graf in the event that I could ever find one. 45mm tb's will be more flexible than larger chokes but could limit ultimate top-end figures.

ECU? Cams? Valve stem diameter? Valve material? Compression ratio? All further stuff for me to consider at this stage rather than pursue one route and find out it is flawed after execution...

 

Are you intending on DIY? End use?

 

I think there's very little in it. The early heads have more port area which can be opened out, but the later ones have an improved water jacket, which cools the ports better (hence the reduced scope for porting). The ABF heads are better as standard, as they don't have a shrouding problem on the exhaust valves, but once that's resolved on the KR head they might be slightly better, if anything.

 

Hi Chris, some DIY, (the slightly easier parts such as putting everything together, sourcing parts from various places, writing cheques, etc) The serious stuff will be left to suitable professionals.

As for use, this will be both for trackday and road, so it needs to get through an emissions test, and be able to perform a standing uphill start without dialling up 6k...

 

I am amazed. Was at Loton park last July and a chap called Ralph Pinder was there with a very quick 205 - British Sprint Champs Car - and he's doing 59's. FTD was a DJ Firehawk single seater who put down a 50 sec run.

SS's should be in a different league to saloons - do they carry extra ballast or run with only one gear down your way ?

 

Hmmm, part of me is thinking those professionals will dictate the components, eg compression ratios and so forth. They'd know what they intend to turn out, what they work with, and one will refuse to deal with others ideas, outright, partly because they have their own ideas and partly because they can charge for it.

The base point is high compression, forged pistons, optional rods, big cams and so forth. I'd open discussions with a/the builder.

Emissions you'll need to deal with if it becomes an issue - and it probably will.

 

Fuel aswell...you will need to be on some fairly high octane fuel to run that sort of power...hope you have a 'V' Power petrol station nearby :-)

 

Most engine builders will want to build their engine using their own 'brand' of parts ie these pistons, these rods,crank,headwork,cams,standalone ECU,injectors, etc because they know what power to expect have done it before, it works and can land it on a plate for you ie it does what it says on the packet.

Also you would be able to run 2 maps one for road and one for track applications this might get you around the MOT emissions issues as if your running 250 it will be no where near.

IIRC was'nt the idea of the GRAf heads to change the angle of the inlet or the exhaust valve's

 

Also the money difference between 230-250 bhp would be better spent on driver training IMO.

No offence as i have no idea who you are or ability. Just something a wise old man told me once.