one last question-keep the air mass meter or not?

[mongoose]

Surely someone on here knows?

[joospeed]

Maybe yours could be the car to find out on ..

get it mapped as you want to, ie throttle versus revs or whichever method you *think* might be best but just do a really quick job to get the engine to run on the dyno, then just map full throttle.

now fit the airflow meter, no need to wire it up to the omex at this stage as all you're interested in is the effect of adding the meter to the airflow.
now go back and just map full throttle again .. time on the rollers is reduced to a minimum since all we're interested in is proving the theory.

has the car gained 15lbs of torque at any point? If not then it's *not true, if it gains 15lbs torque then it *is true.

Job done, definitive answer

whichever version gives you the highest figures, use it and then go on and map it all properly. If this is the *with airflow meter version then obviously wire it into the omex at this point.

best wishes

Joo

[mongoose]

joospeed said:

Maybe yours could be the car to find out on .. get it mapped as you want to, ie throttle versus revs or whichever method you *think* might be best but just do a really quick job to get the engine to run on the dyno, then just map full throttle. now fit the airflow meter, no need to wire it up to the omex at this stage as all you're interested in is the effect of adding the meter to the airflow. now go back and just map full throttle again .. time on the rollers is reduced to a minimum since all we're interested in is proving the theory. has the car gained 15lbs of torque at any point? If not then it's *not true, if it gains 15lbs torque then it *is true. Job done, definitive answer best wishes Joo

Cheers Joolz,that makes a lot of sense.When discussing the fitment of the omex system with Shaun(v8d),im sure he said he'd be removing the afm.I'd be surprised if he wanted to do this,if it would have a negative effect.Therefore i couldnt understand Marks' comments that removing the afm,which i realise has a somewhat restrictive inner diameter,would have a negative effect.If my guess is correct,then i find Marks comments misleading,as hes talking about removing an afm which isnt standard anyway.Hopefully he will come back and clarify.

[2 sheds]

Curiously adding a restrictor in the right place can sometimes help, in the case of the AFM it is normally positioned just before a 90 bend leading into the plenum, my theory is that speeding up the air at that point can assist flow though the bend.
With the Rover V8 every application is different, your tests may produce a result that wouldn't apply to the next engine ? look forward to results though.

[joospeed]

hmm ..

curiously logic, my own limited knowledge (maybe that's the problem) of Bernouille/Navier-Stokes, and lastly the bloke opposite me who has a BSc in materials engineering which encompasses some aspects of fluid dynamics all suggest this wouldn't be the case.

I'm still looking for some definitive info on this.

Nice use of the each-way bet there Tim .. lmao.

[GreenV8S]

Don't know about Navier-wossname or materials engineering, but it seems to me that flow round a curve is more likely to stay attached if you get rid of the boundary layer, which from the look of it I suspect the AFM from do.

[joospeed]

GreenV8S said:

Don't know about Navier-wossname or materials engineering, but it seems to me that flow round a curve is more likely to stay attached if you get rid of the boundary layer, which from the look of it I suspect the AFM from do.

lol .. mistyped the most crucial part of then sentence there.

I would have thought that if you want to minimise the effect of boundary layer attachment and the shear to the free moving air you'd want as alrge a cross section on the curve as was practical for the application.

I can't see any benefits of momentun ramming when you still have to enter the plenum. I would think any momentum ramming would only be of interest in the trumpet / port runner.

My own thinking is there's so many area section changes on the run into the plenum that there would be no tuning effect of anything upstream of the butterfly, but that there could be airflow limitations due to fluid flow effects. I would expect these to only limit hp production on high airflow engines.

Really looking forward to the test results also really keen to hear Tim's thoughts on the fluid flow of the rover intake and if there's ever been any velocity/flow rate probing of the TVR intake system.

What does the Hardcastle book say on the subject?

[GreenV8S]

Don't know about all that complicated stuff, just suggesting that there are some possible benefits to having an AFM fitted. At the end of the day the only way to know for sure is to try it, and sod's law says it's probably going to vary from car to car.

I did try some static pressure tests a few months ago on my very early ACT plenum system, the static pressure drop across the 5AM hotware was slightly more than the dynamic pressure I calculated from the AFM choke at 260 bhp. I fancy the static pressure drop was reduced slightly by changing to the 20AM, but it is hard to be sure. It's hard to get an accurate pressure reading when you're using a boost gauge as a very crude pressure measuring device at the top end of the rev range on full noise. I thought this might be a useful way to test the before/after effect of induction changes (outside the area of strong pulse tuning effects) for those of us without easy access to a rolling road?