400hp w210, om606 Turbo or 320cdi?

Naturally-aspirated

16

01-16-2011, 12:09 PM #23

Very interesting guys, thankyou - thankyou to Tuikku for your experiences too.

So I think what we are saying, if we take is that the 320cdi will stand up to 400hp fine and the auto box will too. But, it will need more air than the stock turbo can give and more fuel.

ForcedInduction looked at the S200 series and I think they are too big, most of that stuff will support up to 500hp and not being VNT if I wanted to keep sub-2000rpm spool up and bearing in mind the CDi doesn't need as much air as the idi I think something not quite as large for this street perfect 350-400hp.

Turning to the fueling issue, what's this air in the lines problem? As mentioned, just use a facet lift pump by the tank to push 4/5psi and make sure the fuel is under slight presusre to the pump. Even a 400bhp vehicle on full throttle doesn't use much fuel, the rate a lift pump can pour out fuel far exceeds the rate the engine can burn it. If there is still a problem, close loop the under bonnet fuel lines and put in a heat exchangeer, that way the fuel circulates round and is just 'topped up' in the circuit by fresh fuel from the tank pump. This system is well used on vegoil conversion.

Turning to the HP pump, what volume of fuel will it pump from an open outlet (no pressure) given a good supply (lift pump capable of oversupplying it at around 5psi)? If it simply can't pump the volume, then a bigger or twin HP pumps will be needed. But if it's a case that the pump is struggling more due to not being able to shift the required fuel throgh tiny nozzles at huge pressure, what about lowering the pump pressure by 500 or 1,000 bar and greatly increasing injector nozzle size. This will then be closer to injection pump DI pressures (though still higher) and as we know those 'large' hole injectos have no trouble flowing. The pump wouldn't have to raise as much pressure, would drag on the engine less and it would be easier to get the fuel into the engine. Personally I think this would be more interesting than the current common practice of pushing up rail pressure further and putting even more strain on the pump trying to force more fuel through tiny nozzles.

Regarding turbo, it would be great to know what flow rate and what psi boost you are running to make 300hp on the 3.0 tuikku. With better flow (1 more cylinder, 0.2 litre more displacement) from the 3.2 it shoudl require slightly less boost pressure to flow the same. From that, a flow and boost rate could be worked out for 400hp on the 6-cylinder.

Then there will be the matter of seeing if one VNT can be found that can raise that PR while still being efficient and can still spool up like the stock turbo. I'm going to guess not, not without creating a lot of EMP/poor efficiency/hot charge at the upper rpm on boost. I think it may be more sensible to run compounds, with the stock small turbo fed by a big vnt sized purely to deliver the total max airflow. During low speed operation, if you adjust the stop screw you can get these vnt's to practically shut off exhaust flow completely, so you could have the small turbo spun up by all the exhaust. As the EMP starts to rise, the large turbo vnt starts to open to control the EMP (the small turbo staying on a 'max boost' setting) which spools up the large turbo and you then get double compression of the intake air and a pressure ratio of at least 5 is possible with efficiency - easily able to push 4/500bhp worth of air into the engine. As serious exhaust flow starts due to the boost/power the engine is now pushing, the big vnt vanes open more and more and prevent the EMP getting too high, if needed the small VNT can also start to open up it's vanes to prevent excess EMP too - the combination of those would do awa with any need for a wastegate/EMP dump valve and also avoid extra plumbing.

Anyhow, there's some ideas.....

Greg.

greg123