519" SOHC Build

[Qikbbstang]

level sight glass so that the thrown oil or oil wall would not be so much of a factor?
   Just always figured that windage could really effect the level of a sight glass by placement and actual probes entrance configurations, thank goodness you run a vac pump which obviously should help cut down on the windage factor.   Great to watch!

[My427stang]

Jay, awesome motor and glad to see the results from intake port length changes.

Not sure how easy it would be to measure on the motor, but could you do some before and after calcs based on the old Ramcharger's wave tuning math?

L = 80500 / N            
            
L = duct length (inches) from Plenum ( the first reflection point) to the back of the intake valve.            
N = Engine RPM for maximum tuning effect

Solve for N before and after and see which one was closer to where you made power?  Needless to say the shorter stacks did well so it should be closer, but it would be interesting to see what the numbers came out to be.  For an IR manifold L should be from the valve to the end of the stack      

      

[jayb]

Jay understand I know little to nothing.....
Would running 2 different length stacks maybe flatten the torque curve?
My Sprint Car racing cousin does that on a slick track with a SBC says it widens the torque curve.

I'll bet that would actually work pretty well; probably would make the engine much less peaky.

[jayb]

level sight glass so that the thrown oil or oil wall would not be so much of a factor?
   Just always figured that windage could really effect the level of a sight glass by placement and actual probes entrance configurations, thank goodness you run a vac pump which obviously should help cut down on the windage factor.   Great to watch!

There's no baffling in front of the sight tube openings, BB, so you are definitely seeing some windage effect in the tube.  I think it is fairly clear that as the engine speed climbs and the oil level comes up, that is probably due to windage.  What I keyed in on was the drop in the oil level when the engine finished the pull; despite dropping in the video it remained plenty high to ensure that the pickup was covered.

[jayb]

Jay, awesome motor and glad to see the results from intake port length changes.

Not sure how easy it would be to measure on the motor, but could you do some before and after calcs based on the old Ramcharger's wave tuning math?

L = 80500 / N            
            
L = duct length (inches) from Plenum ( the first reflection point) to the back of the intake valve.            
N = Engine RPM for maximum tuning effect

Solve for N before and after and see which one was closer to where you made power?  Needless to say the shorter stacks did well so it should be closer, but it would be interesting to see what the numbers came out to be.  For an IR manifold L should be from the valve to the end of the stack

L for the two different ram tube lengths is 15.75 and 17.75.  Based on the formula the engine should tune at 5100 RPM for the short tubes and 4500 RPM for the long tubes.  Not to close to what really happened, BUT it is very interesting that the difference between the projected speeds is 600 RPM, and that is the amount of the shift I saw in the torque peak.

I have a program called Pipemax that calculates this kind of stuff, and it has also not proven perfectly accurate for these kinds of calculations, but it does seem to be pretty good at predicting a delta in the peaks.  Pipemax told me that a 2" tube length change would give a 600 RPM increase in the peak torque RPM, and that's what happened.

[Cyclone Joe]

Thanks Jay, I had hoped the vapors were from the vacuum pump vent.  It makes sense, the vacuum pumps at work do the same thing when they're pulling vacuum.

Joe

[cdmbill2]

Jay, awesome results. The comparison with Barry's 527 is fascinating. Your IR setup is a clinic on Heimholtz resonance tuning. Did you see any EGT or AFR correlation to the 'lumps' in the torque curve? Since the fuel curve is fixed, the changes would have to be related to reversion/ram tuning from the changing air flow resulting from the individula runners, IMHO.

Secondly, the oil level, another priceless bit of information. Did you happen to log the crankcase pressure and oil pressure? My theory being that when you pull the throttle back the crankcase pressurization past the rings falls to almost nothing, yet with engine speed high the pump is still at maximum and literally sucks/holds the oil in the top of the motor until it releases as RPM rapidly falls. The net no big deal unless you see a huge drop in oil pressure at that moment which coupled with heavy braking at the end of the 1/4 mile could starve the pick-up briefly.

As an aside I don't see anything like that on mine and I have videotaped the guages to be sure. Yes different pans, engines but similar in terms of front sump, vacuum pump, RPM range and big displacement.

The net absent a big pressure drop no sweat, right?

Now could you please build an original 427 cu. in. engine for Drag Week Street Race NA? Please?

[Qikbbstang]

http://www.dragzine.com/features/interviews/randy-seward-the-crazy-story-behind-4000-miles-in-an-8-sec-stang/

[jayb]

No Bill, I will not build a stock 427 for Drag Week LOL!  I don't know why you're worried with that 1000 HP monster under your hood 

The hilly torque curve is not reflected in the exhaust gas temps, but it is definitely reflected in the A/F numbers.  I agree with you that this is all part of the sonic tuning effect.  The engines I've run this induction setup on are nearly impossible to tune in the 3000-5000 RPM range; you need a bunch more resolution in the VE map to get close.  When I did my first SOHC with this manifold converted to EFI I ended up with RPM increments of 300 for part of this range to get the A/F stable.  I concluded a while back that kind of effort just wasn't worth it, and so I end up living with A/F numbers that vary widely in this range.

The dyno does log the crankcase pressure and oil pressure, but unfortunately once the engine reaches the end of the pull it stops logging, so I don't have the data on what happens when the throttle is pulled back.  That would be interesting to see.  Oil pressure drops during the pull, after the first 500 RPM or so, but it typically would start at 95 psi, and maybe drop to 65 psi by 7500 RPM.  Vacuum was stable during the pull at around 14"-15". 

I'm thinking this engine is probably good for 9.70s or 9.80s in the Galaxie.  We will see...

[My427stang]

Jay, awesome motor and glad to see the results from intake port length changes.

Not sure how easy it would be to measure on the motor, but could you do some before and after calcs based on the old Ramcharger's wave tuning math?

L = 80500 / N            
            
L = duct length (inches) from Plenum ( the first reflection point) to the back of the intake valve.            
N = Engine RPM for maximum tuning effect

Solve for N before and after and see which one was closer to where you made power?  Needless to say the shorter stacks did well so it should be closer, but it would be interesting to see what the numbers came out to be.  For an IR manifold L should be from the valve to the end of the stack

L for the two different ram tube lengths is 15.75 and 17.75.  Based on the formula the engine should tune at 5100 RPM for the short tubes and 4500 RPM for the long tubes.  Not to close to what really happened, BUT it is very interesting that the difference between the projected speeds is 600 RPM, and that is the amount of the shift I saw in the torque peak.

I have a program called Pipemax that calculates this kind of stuff, and it has also not proven perfectly accurate for these kinds of calculations, but it does seem to be pretty good at predicting a delta in the peaks.  Pipemax told me that a 2" tube length change would give a 600 RPM increase in the peak torque RPM, and that's what happened.

Neat stuff Jay, I am familiar with Larry Meaux's Pipemax, although I haven't built anything since I bought it.     USAF keeps getting in the way lately.   

1 more year until they send me off to finishing school yet again LOL, 2 years until retirement eligible, either will give me time to play more

I wonder if there is a second harmonic coming into play with the long runners?   

Another question, do you run any line damper on the EFI?  I don't have a way to log it on my car, some claim there is power to be had in an inline fuel pressure damper, on a dyno it could be seen with wiggle type gauge. 

The larger the injectors, the more it can affect other injectors.  I run one one in addition to the regulator, and considered running one on each rail.  Before and after it did seem a bit smoother, but it could have been my wallet talking

[Barry_R]

Very interesting data indeed seing them laid out like that.  The two engines are not directly comparable - significant differences in heads and cam, as well as competitive intent, dyno brand & cell.  But as Bill noted you can really see the wave tuning impact of the stacks as compared to the plenum intake.

Some of your prior testing ha shown significant gains in midrange with the stacks & that was what I was looking for.  I have a feeling that if you played with diameters and lengths you'd see that big tuning wave again - just seeing how it "comes on" here.  Probably very application dependent.

[Qikbbstang]

Decades ago I sold an enormous ASME flanged "mushroom" like looking filter housing of Stainless Steel that accepted a single cylindrical filter element (much like a K&N but industrial grade-you don't see light holes in the media) about 2-1/2ft x 3ft for an equally enormous Sullair two cylinder air compressor. We're talking about something like a 16" bore and  stroke measured in feet.  About a week after it was installed I got a call that every weld on the filter housing was cracking and it was falling apart. Long story short the 15 foot length of the inlet piping was right in the "critical length zone" as determined by a formula in that industry for that bore and stroke and RPM. The piping was lengthened about ten additional feet, the housing repaired and there never was another cracked weld.  The fact that serious guage metal was shattered like it was hit by a sledge hammer was a learning experience and indicated the forces inherent in intake pulses and perhaps just as likely in exhaust pulses
    Nothing else has ever impressed me as to the effects of intakes pulse strength until I saw the deviations from so small a change as those short vs long tubes.

[jayb]

Neat stuff Jay, I am familiar with Larry Meaux's Pipemax, although I haven't built anything since I bought it.     USAF keeps getting in the way lately.   

1 more year until they send me off to finishing school yet again LOL, 2 years until retirement eligible, either will give me time to play more

I wonder if there is a second harmonic coming into play with the long runners?   

Another question, do you run any line damper on the EFI?  I don't have a way to log it on my car, some claim there is power to be had in an inline fuel pressure damper, on a dyno it could be seen with wiggle type gauge. 

The larger the injectors, the more it can affect other injectors.  I run one one in addition to the regulator, and considered running one on each rail.  Before and after it did seem a bit smoother, but it could have been my wallet talking

I'm certain that you are seeing two different harmonics with the two different torque peaks.  Probably the second and third harmonics, if you can believe what Pipemax is saying. 

I'm not running any kind of line damper in the fuel system, but I do run the large 11/16" bore fuel rails and #10 AN fuel lines, and keep the pressure in the 45 psi range.  The dyno logs the fuel pressure every 100 RPM and I don't see any significant variations.  From the start of the pull to the end I do see a fairly steady drop in fuel pressure of 2-3 psi, but it isn't bouncing around any.  That would be a bigger issue if the fuel rails and fuel lines were smaller diameter, I think.

[jayb]

Very interesting data indeed seing them laid out like that.  The two engines are not directly comparable - significant differences in heads and cam, as well as competitive intent, dyno brand & cell.  But as Bill noted you can really see the wave tuning impact of the stacks as compared to the plenum intake.

Some of your prior testing ha shown significant gains in midrange with the stacks & that was what I was looking for.  I have a feeling that if you played with diameters and lengths you'd see that big tuning wave again - just seeing how it "comes on" here.  Probably very application dependent.

I agree, after thinking about this a little I'm sure that the large stack diameter and large throttle butterfly diameter of the Hilborn setup is hurting low end torque production.  On the other hand, it is needed for top end power, and in fact I've had a few knowledgeable people tell me that the injector butterflies are really too small for this engine.  I guess this is why you don't see the Hilborn style setups on a lot of drag cars. 

On the other hand, they sure look cool 

[cdmbill2]

I think the fuel rail issue resolves itself with a large ID, the Wilson Manifolds 'D' shape rails I have are similar in x-sectional area to yours and coupled with the large Aeromotive EFI regulator and #10 lines in and out I don't see fuel pressure variations through the RPM range or heading down track.

Our biggest fuel pressure issue was on the engine dyno where the flow meters to derive BSFC numbers caused an issue. We had to take the retunr meter out to solve the problem and still saw 2-3 PSI drop at the top of the pull similar to yours. I don't see that in the car.