Basically a shelf piston but I added some options such as lateral gas ports, max lightening, coated skirts, etc. It isn't a super trick setup, Molnar crank and rods and semi-custom pistons. Pistons have a very small dish in them to make the compression 10.8 to one. Heads are Trick Flow 270 right out of the box. No porting or machine work on the heads. They were inspected and cleaned and bolted on.

Andy,
Were any other Camshafts tested during any of the trick flow head tests? I am getting the 270 heads and they are going on a 12:1 511. So I am curious if another 5-10 degrees would be worth it.

Wow Andy you do know how to get awesome power from your Mopars !! Ron

Just curious Andy if you know the flow #'s on the OOB 270 Trick Flow heads you used on the eng ? Thanks , Ron

Ron trick flow site advertises these numbers ootb intake
.100- 72
.200- 154
.300- 230
.400- 288
.500- 322
.600- 343
.700- 352

exhaust
.100-58
.200-130
.300-186
.400-222
.500-243
.600-253
.700-262

I have not done any cam testing with the 270 heads. The cam I used for the 270 heads is the one that was best with the 240 heads. I'm pretty sure I can find some more power if I start testing cams. Now that I have the 270 heads and the ported intake I'm sure the engine would respond to a little more area under the curve. I'm kind of busy building the Duster at the moment but if I get a little free time I'll research some cams for this engine and then see if I can get it back on the dyno.

Thanks Ron. Not sure I really know in advance how to make power but if you try enough things eventually some stuff works. I chased my tail with rocker arm ratios and cam grinds and crappy intake manifolds and spacers that didn't work and all of that stuff. First pull with the 470 was 620 hp so we've found 150 hp over the past 18 months.

I'm sure that motor combo could benefit from more duration, provided the car has the right pieces to make use of it.



Exhaust numbers are with a flow tube attached.

Nice work, thats what should happen when one keeps testing and testing and re-testing stuff. I think a lot of guys on here would be supprised how much they could gain from trying some different manifolds, carbs, spacers, rocer geometry, rocker ratio... vs the typical just throw more cylinder head, cam, and compression at it.

Regarding the crankcase. While the pistons are going up and down they are disp[lacing volume on the top of the piston but it cannot nbe any different on the bottom of the piston. The pistons are moving a lot of air in the crankcase and it takes energy to compress that air. Then when it expands back all of the energy doesn't come back. There's also the fact that air has to rush around the spinning crank, connecting rods, etc. So by adding cubic inches of volume to the crankcase, the air doesn't have to be compressed that much because the piston is working with a larger volume.
The vacuum pump attacks the problem another way by making the crankcase air much less dense. It doesn't take as much energy to move around this less dense air. The vacuum might also assist in ring loading but I'm not sure how big the effect is.

One problem will pop up with decreased crankcase pressure, and that's technically called Net Positive Suction Head (NPSH). The oil pump doesn't suck oil in, it's the absolute pressure of the atmosphere that pushes the oil into the pump inlet. When you decrease the absolute pressure in the crankcase, it reduces the pressure available to push the oil into the oil pump inlet. I have a friend who had problems with oil pressure at the end of the track because his vacuum pump was so effective.

R.

When I first heard of the oil starvation problems with motors running vacuum pumps I thought it was due to tight of clearances on the wrist pins to rod and pistons due to most pin oiling being splash oiling.
The oil pump is a suction pump also but it forces liquid through a restrictor, the engine oiling system and has a high pressure bypass system built into the pump so the motor will have a maximum oil pressure at the higher RPM. The oil pump has to battle the negative pressures above the oil level to suck oil into it, or does it
Using a vacuum pump does allow thinner rings to seal better which allows the motor to make more power with less oil contamination in the combustion chambers
As well as stop some of those pesky tiny oil leaks

That's funny Cab , 20 or so years ago I had similar issues on a customers stock 308ci Holden , after 20 minutes the motor would stall . Took a little while to work that one out , vented oil filler cap solved it .

Tex

I modified a PCV so it would flow slightly under vacuum and then put it on the vent side. I now have 2ish inches of crankcase vacuum and it has made a world of difference in throttle response and power/mpg.

I think the PCV has been on the wrong end of the crankcase vent sequence.

Wow thats some nice #'s. I believe they do come CNC ported right out of the box ? Thanks Viperblue72. Ron

And us Mopar people do thank you as you do alot of work in testing parts and letting us know what works in many combo's and myself I thank you. I really enjoy reading about your dyno' runs. Ron

Can you explain this "wrong side" theory please...........

i am guessing to position the valve where the air inters the engine?

Is this referring to using manifold vacuum via pvc to pull a vacuum on the crankcase ?

I used some home depot parts to install a PCV in the breather line. However I opened up a passage so the PCV flows backwards.

Restricting the vent flow creates negative CC pressure. I couldn't believe how off idle throttle response and street manners improved. Mileage is up as well.

I have pics but my brand new phone and antique PC won't link, so I am working to get that fixed.

varunner:
I'm just harnessing the vacuum energy pulling air through the crankcase already.

A PCV is a one way valve right? The spring shoves it closed with no vacuum and opens with around 2 + inches of vacuum, correct?
If you apply vacuum to the ball side of the valve doesn't that suck it closed?