exactly that makes peak torque of 162ftlb...at 6.5k

ahh the other thing would also ideally be an exhaust manifold made to suit the characteristics of the engine, this cold be the difference between 220 and 240 bhp.

Hardly in the same realms as a reshaped and oversized valve and seats is it?

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Regarding bike bodies, at the end of the day all it is is a bit of metal with a butterfly in it, no reason one should be better of worse than the other. The normal reason bike bodies dont work is because they are spaced badly, held with rubber connectors and dont use trumpets, ie, shit!!

Colins set up uses a nice long smooth intake manifold, and decent sized and shaped trumpets.

Cams wise as i say im looking at the newman PH2 spec, there is no reason not to use of of petert's cams, DrSarty has had great power with his.

Up to you with the big valves, but its soo much money to get done right, alot of places could fit big valves for you, but finding someone to 'work' the head to make use of them will cost a bomb. The seats are 3 angle as stock, but can be improved on.

Im not aiming for any particular figure with mine, above 220bhp and as close to 200ft lb torque as i can will be nice, but, without seeing over 7250 ish rpm limiter, ie, stock.

Manifold wise, im thinking now and having done a fair amount of research that the shape and length of it will work well with this spec engine, ie, similar power placement, just more of it. Its the primary diameter that seems to be the restriction over 230bhp.

Id like to have a manifold made, to resemble the stocker but with larger primaries and feed into a minimum of a 2.¼ inch system, peter taylor suggested somewhere that anything over 220bhp would be ok with 2.5 inch.

To spec a manifold seems quite involved, rpms, bore, stroke, cam specs, port sizes etc etc.

I think ill try and keep it simple on mine, have a stock manifold copied maybe with larger primaries, failing that something like an equal length maniflow thats not designed for a BTCC car.

Whilst im here i may aswell also add, going with a big valve head is even more un-necessary on an engine thats not going to be revved high, if your aim is to make a lot of horsepower at higher RPM's the bigger valves and ports 'may' help you on the way to high figures, probably at the sacrifice of more bottom end power.

With these bigger bore, longer stroke, not as high revving engines the increase in displacement makes the head work better than in a 1998cc lump.

Picture this, you have a running open ended garden hose, now cover half the end with your thumb, we've all done it. What happens? that water is now travelling alot faster! its not all about massive ports and valves, its about flow and intake charge velocity.

One engine i have had a lot of dealings with is the Honda CRF250 motocross engine, when it first came out in 2004 the ports were huge, gaping great round things, 2005 model came out, slightly smaller ports, flat bottomed slightly = more power and torque, 2006 came, even smaller ports, even flatter bottomed = even more power and torque again, the same valve sizes where used, the same carb and basically the same cam, though this engine revved to 13.5k it had useable power from about 5k up to the limiter, my particular bike was 'breathed' on (a head clean up, 14:1 compression, stock cam re-timed, advanced ignition by 4 degrees, full exhaust system, and a carb size reducer, from 40mm to 37mm), it made max BHP (worked out to be around 28% increase over stock power of a 30 something bhp race engine) at 11.5k and dropped one bhp all the way to 13.5k, it made max torque at 9.5k, but the torque curve was really quite smooth and flat before peak for an engine like this and didnt drop off like a stock engine did.

It was an incredibly usable engine, i raced it against 450 4 strokes and 250 2 strokes with reasonable success, mainly because it was easy to ride, most 250 four stroke motocross engines you have to keep on the boil, miss a gear and they will bog out, mine was like trundle the tractor compared to most others.

Its a bit off on a tangent, but most people bolt an exhaust system on their mx bikes and start chasing BHP numbers, i was different, i was chasing usability and torques, and a by product of that was BHP.

dented_vts is the new Mr. Whippy and I claim my

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Project é - my 306 project thread.

My comment was regarding that level of torque AT 9k rpm on standard size valves- ie those levels of torque on a 4pot 2 litre. That is quite different from that level of torque at say 5k. And different from engines with significantly different cylinder capacities. Formula one is the pinnacle in engine design- the problem is you just can't hit those rpm's with vavles operated by springs. 900bhp+ from 2.4litres and just look at the massive inlet valve area vs. capacity. they use 10 cylinders not 4 for a reason. The current Formula one engines could make significantly more power if they were not rev limited by regulation.

Agreed from a full race build 2ltr 4 pot such figures are possible as up to 130% volumetric efficiency PEAK has been shown to be achieved with pulse tuned set ups- but how many ft/lbs does that equate to? Inducting air at 30% more than atmospheric pressure is quite an achievement

There was a famous E30 M3 engine that was said to make about 300bhp that revved to about 10300 i think- anyone got any details as the inlet and exhaust diameters and tube lengths may be of interest here. I'll search my machine, think it was by a German tuning company.

Very interesting- did you conclude that the port shaping was creating unwanted turbulence and hence hampering flow? I made a mistake which was kinda related- fitted near standard cams to a head that had been ported to optimise flow at very high lift ( at the time i had little experience and thought if it was ported it was optimal for all cams!). Didn't perform well at all- not much over a standard head. Friend bought it, fitted it with massive cams and wow, huge difference.

It was Hondas doing, every year it made better power and the main thing to change was the port shape and size. I think it works just as i described crudely, mixture speed/velocity was much improved, probably a better mix of air and fuel and better cylinder filling.

Our engines tend to be around 90lbft/litre at peak power. If you can get a good spread of efficiency, there isn't the need for revs in most cases.

I've only seen the Pumaracing TBs on Kate Osbourne's 205. They were always falling apart. Maybe the ravages of time, but not ideal.

The AT-Power bodies are being pushed hard by suppliers on many forums. Clearly the look well made and finished, but be cautious about zealous sales pitch regarding their design. The have not re-invented the wheel as far as I can see. The closest comparison I've seen has been between a 1.6 16v Saxo running the ATP direct to head bodies and Catcam "708s" and a 106 1.6 16v (it's the same engine), also on "708"s, but with our GSXR1000 based TB kit. Just to be clear, both these cars were tested on newly installed Supeflow rolling roads and I had no involvement:

ATP Bodies Saxo:


GSXR kit 106:


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