if anyone feels the urge - PM me as I would like a data file to do an xy plot.

Why?...I'm cross checking a previous (now confirmed invalid) assumption - that MAP is roughly constant through the rpm range (I have no logging) since I was previously assuming the SC was pumping a displacement into a volume consumer which were both linked via the crank.
ie:
engine needs X at 3000rpm screws pump Y resulting in an OE design within the manifold cavity of 14.5psi
engine needs 2X at 6000rpm screws pump 2Y resulting in an OE design within the manifold cavity of 14.5psi.....

 

MAP reads atmospheric pressure + boost so once you're going full throttle shouldn't the reading be somewhat constant if the boost is constant?

 

okay - so I got a zdl file from a dashdaq run - but dont actually have a dashdaq myself - so looking for the easiest way to convert it to a csv or txt file.

I found a txt/csv converter over at zeitronix, but not the other way.....
TIA

 

Here's a link to the viewer for free:

http://www.zeitronix.com/zdl/install....1.6_Setup.exe

 

results - probably no suprise to anyone logging - but of interest to me....
thanks to those supplying the data
It does (above 3000rpm) to some extent support the notion that the boost is only marginally increasing with rpm once it gets moving.
I suspect some of the increase is backpressure from the inlet manifold/valves etc....but only guessing.

the increase each "gear cycle" is due to a 10degC (18F) temp increase each gear cycle
the cooling system not keeping up with the Jones's......so to speak

 

Mate I dont get all that your saying here but the SC is mechanically connected to the engine and thus the inpeller speed and crank are related by the pulley ratios. The level of boost is related to the density of the charge going into the SC.

THis is controlled by you with the TB, normally the inlet ( behind the TB ) is in a vacuum; which is not a vacuum but actually a pressure below ambient. If your WOT, the boost sorta stays the same depending on inlet restrictions and engine design factors.

The ambient atmospheric pressure is typically 14.7 PSIG which is complecated by the fact that most gauges measure "Vacuum" or below ambient pressures in inches of mercury. ???
That is silly as 14.7 PSIG is about 29.92 inches of mercury, why change the terms?? I guess that it relates to the testing equipment of the old days.. Today your blood pressure is still measured in millimeters of mercury. ???

Woody

 

Sorry if I'm preaching SC101...
probably more for my benefit than anyone elses.

....Negating temperature effects....the SC output to cylinder consumption arrangement is what determines plenum pressure.
The SC pumps it in and the cylinder taketh away. The differential being a residual "inventory" or what we call manifold pressure.
In an extreme example if the cylinders were consuming 20L/sec and the SC was only supplying 1L/sec the residual would be squat.
In our case however....the SC is producing and the cylinders are taking resulting in a pressure of 14.5psig
Change the pulley ratio - obviously changes the plenum inventory...increasing the pump, but the cylinders can only take it away at 370cfm....so the psi in the plenum goes up.
I'd like to do a dynamic model of this...(one day).
Just gotta use a good figure for the CAC/plenum volumes prior to the valves. Might start with 2Litres/quarts....

.....Yes - I'm a time waster.......

 

I dont want to step on too many egos here, but ....the interesting thing to note from the chart in the previous post is that the 1st gear pull is probably the most representative of one's actual - present "boost" setup. In this case...20.5psi

Boost does increase in 2nd and 3rd gear pulls - but it isnt really the result of the SC pumping air, more rather it's pumping heat int othe system and the heat is providing the increase in pressure.....

Regardless - boost isnt the end game here - it's density....more density - more cfm, more g/sec more fuel...and hopefully out of all that - more power....
here's another chart of intake density for the same pull.....
It has to be noted - the AIT figures out of the csv file from the zeitronix log were a little coarse....but the MAP and rpm are good - hence the resultant density is a relatively sound calculation.....

Interesting - max density is 1st and 2nd gear upto 50degC (122F)
- 3rd and 4th gear - although the boost gauge is making you feel good (previous graph) density's droping away .....temperature.....
Fortunately in this case - the map is setup to pump more fuel in regardless - maintaining cc/sec and AFR's journey into the low 11's.

 

Well, gentlemen. I'm finding out more and more as this old guy tries to learn about all the new systems that make engines go. In other words, the carbs, the intakes of old, the distributors, coils, and such, are all replaced today by computers, ECU, throttle bodies, etc. But, one thing doesn't change is just how much a cylinder can take. So, IF what I'm am hearing, is we can only throw so much into each cylinder, and if we have surpassed that point, time to bore out the cylinder and go larger pistons....Makes since you want find out just where the stopping point is before you go negative. Since I don't understand everything yet, re-learning today's engines and engine management systems, I just keep making changes based on performance. As long as my times keep coming down, then, that is a good mod. Once I flat-line, I'm done. I thankfully don't have to do all the testing, as I have the Rudy's, the Steve's, the Antony's, etc, and etc doing a lot of the testing for me, and the Rob's to supply the parts...so keep testing and I will keep learning....

 

I dont think the virtual wall has been hit yet.
Again - it all comes down to one key item which Woody is chasing - ie: cooling. That maybe a tougher nut to crack than we think though.
Keep your AIT's down and your density will follow.
Again - dont want to sound like I'm preaching to the converted....but I've been thinking this since very early on in the piece, and the raw data is lending more and more weight to the story.

Unfortunately from what I've also picked up the stock Charge Air Cooler IC pump circuit is only good for 10-12kW (40,000BTU's) rejection.

The most representative rpm I could choose from the data for all 4 gear pulls is 4700rpm.
Plugging the AIT's and psi1/psi2 figures into my enigne calc/model yielded the following...

..Gear.......AIT..........SC discharge T*...Heat rejection from cooler...density kg/m3
1st gear....39C (101F)....97C (207F)......-21kW (71 kBTU/hr)...............2.55
2nd gear...44C (111F)....99C (211F)......-20kW (68 kBTU/hr)...............2.56
3rd gear...58C (136F)....101C (215F).....-15kW (52 kBTU/hr)...............2.50
4th gear...70C (158F)....103C (218F).....-11kW (39 kBTU/hr)...............2.45

*assumed 20C/68F intake temp.for every +5C = +7C to SC Discharge Temp (DCT).

Note - the max density achieved was at around 5400rpm was 2.7kg/m3
So you can see the density is dropping after peaking in the 2nd gear pull, also the rejection is dropping.

I guess without stating the bleeding obvious - keeping the AIT's down below 120F is key.....

Note - the high SC DCT's of 215 & 218F (based on 68F in) - I wouldnt be too alarmed by this....it aint boiling....
First, thats what's only entering the CAC gas side, that's gotta pass through the matrix of aluminium walls of the CAC where it will loose a few degF before it hits the water/coolant. Keeping your glycol up will also prevent boiling up well into the 110C/220F's, so no need to panic - unless you aren't running glycol....

The work by Woody is interesting on this part, but I dont have water temps - so can only guestimate here. The AIT's are measured as air passes out the last chamber of the CAC, which is seeing the incoming cooled water circuit. So I suspect the cooling circuit thermal inertia is already running up by the 3rd gear pull and AIT's are climbing.

For short runs - its possible that the thermal inertia of the large cooling tank setup (some have this) could be of great benfit here. I'm talking instead of the 2L/quart circuit you could run a 5-10L/quart circuit, thus delaying the onset of high AIT's until after your run and then it has the full half hour before the next one to cool down.

note - For those running OEM setups.....stock density is 2.07kg/m3 at 6,000rpm - so in this conversation we are talking here about 30% more density than stock - which effectively means 30% more power than stock - ie: these numbers are right out there.

Again - this isnt a tome in sucking eggs...just my thoughts and calcs.

 

Well, an all aluminum engine, and compressing air, sure does "lean" to the conclusion heat soak might be a problem. I have to come back and thank Rob, and Woody for all their work as well, and a host of others not mentioned working off their own assumptions. All that info and data is sure narrowing down what is a good mod, and what isn't. So, you can better spend the $$$$$ in the right place. As someone who would love to stay with the drag racing, soon to go 1/8 mi only next year...it's all good info...even when you get some who think they know this motor and don't...everything I have bought and installed on the cars so far has had a benefit...and I love that part...

 

I would definitely agree that we are not at a wall. Displacement isn't everything... my buddies 2.8L 7M Supra makes 690rwhp and runs in the low 9's. Of course to see the big gains on our cars, I believe you'd have to pull the power-robbing S/C and throw on a turbo w/ a stand alone fuel management system.

 

Heresy Buggin! The 7M is a 3 liter motor. I actually still have one laying out in the barn... The 5M in the Mark II Supras was 2.8. Same basic block though, lots of interchangeable parts.

 

Our cars are not limited by the displacement but we are at a wall as everybody tops out in the 350-360whp range and this is due to the supercharger design/displacement/efficiency. Just look at a SL600 vs SL55 AMG, SL600 will own it stock for stock and once modded.. no contest. Same goes for other cars with a charger like an 03-04' Cobra can only make so much whp (which is obviously a **** load nevertheless) but once you put a Whipple on it.. here come 130+ mph trap speeds.