Adrian2627 wrote:This is why you shouldn't build a street engine to a power figure but rather a driving experience/style. Power figures are arbitrary at best as mentioned above. Setting out to build and targeting some figure from a forum isn't necessarily going to get you the engine you want especially if you try to cheap out. If you do your research, plan a budget, and make mods to suit you driving style you should then see usable increases. As most people have found these engines respond best to a good tune with the bolt-ons being supporting players. To really get it singing you are going to delve deep into both the engine and your wallet and a lot of unnecessary expense if basing a power figure.
Spot on as always, Adrian
I also hear of these big power n/a H6's and think where is the logic.
Maths and Phsyics don't lie - to produce 180awkw from a n/a H6 is at the very very least 210kw at the flywheel - that's assuming a manual trans and 30kw drivetrain loss (or 14.2% which is less than the general rule of 17-20% drivetrain loss - mind you I also don't agree with a flat percentage as power loss is not generally linear but that's another discussion).
So lets assume 210kw at the fly. To make this power, the engine needs to ingest a peak of about 240 grams per second of air.
With a n/a 3.0 litre, that's a hell of a lot of air to flow.
240 g / second of air is approx 31lb/ min
Assuming 14.7psi atmospheric density, and static intake temp, that's about 418cfm of peak airflow.
Hear me out for a second - but some conservative assumptions I have made for the below calculation are
Bring back peak cfm to 400 to allow for conversion errors
3.0 litre is 180 cubic inches.
Peak power at 7000 (conservative as I've yet to see an unported / cammed h6 make power this high up in the rev range)
Using calculator of VE = (3456 x CFM) / (CID x RPM)
VE = (3456 x 400) / (180 x 7000rpm)
= 1.097 or 110% VE
Generally, unless its a full time race engine, an n/a engine won't go over 100% VE and even then, that's pushing assuming everything is absolutely pristine and on the ragged edge.
180awkw out of an n/a 3.0 litre is not happening without bottom end work to support higher revs, massive cams, extreme headwork and an absolutely spot on tune.
Mick