The purpose of this thread is for those to discuss the results of the shootout. Lets keep it civilized please. :viking:
Thanks for all the hard work. I'm curious, and maybe this was answered elsewhere (I lost track of the original thread some time ago), but did you make multiple passes with each setup, and if so, any idea how the averages of those runs compare? Or to ask it another way, are these charts a best vs best, worst vs worst or ave vs ave comparisons?
Did you guys CC all of the combustion chambers, to account for differences in final CR? Just looking at the torque curves makes me think the PPP heads may have a bit more compression than the MPSCs.... Nice test either way, this has to be a huge job, props to you guys....when you gonna start testing cams, lol?!?! Thanks Mike
Both heads had untouched combustion chambers, but the mopar heads were only milled .005 and the rest of the heads were all milled .020, so we all had an advantage in compression over the Mopar heads.
Each set of heads was given 4 pulls at operating temp. In Chris's car his operating temps are 178F to 195F. During the testing our temperature in O.C. Socal has been in the range of 65F to 75F, inside my shop it's usually 60F Chris complains about that a lot lol. I took the best run of the four pulls. Each set of heads liked the 2nd and 3rd pull the fourth pull just heat soaks the motor to much. Each pull was done in 3rd gear at approx 2,200 RPM's. Fourth gear in these cars is just to long of a pull and it heat soaks the motor very quickly. The bumpy portion of the curve in the begining is from the PT converter I believe.
Gotcha. So was the 'best' always the same number in the sequence? Still, it would be interesting to see the 4 pulls per set graphed together. Might help give a good idea what one can expect from a heatsoaked motor in the various combinations. In addition, since (I assume?) the timing of each pull within each set was consistent between setups (how long by the way?) all conditions would still be equal, so an average is very applicable.
Josh, I have 4 different dynos on 3 different cars. Car 1: PI converter Car 2: PTC converter Car 3: PT converter Car 4: same car as car 3 but stock converter All 4 dynos had the wavy line in the beginning. I think it is the extra tq making it harder for the converter to lock-up. Once we get tcm support, we should be able to offset this by increasing line pressure in the tranny.
We had an independent facility do all of the cc's and flow bench testing to each set of heads. The MPSC's had a cc of 82.4 if I remember correctly. We have all of the cc numbers for the intake, exhaust, and cc. That will be up shortly, trying to make a nice presentation in graphs and charts. A lot of info to bring out.
It's something to that effect. The converter may be called a "2,800" stall. But to me it looks a little tight like it's trying to stall. I've noticed this on all the DCX's that get a stall in my shop. Do you know if they are attempting to get the converter to lock - up immediately? I know some companies have tried it later in the powerband.
Im not real sure what they are attempting, but even a stock converter with 450rwhp has a hard time locking up. Here is a graph of a stock converter not wanting to lock-up. I think it is the extra tq causing some slippage during lockup. I think once we can increase line pressure, it will go away. You see as we increased power, the line got even wavier.
If I remember right increasing line pressure is done via the epc "electronic pressure control" solenoid. I don't think an increase in line pressure will effect the lock up function of the converter. The lock up is in the converter itself. Resembles the clutches in the clutch packs or drums in the transmission itself but just larger. I could be wrong, if someone knows a lot about converters please chime in because this is annoying.
Thanks guys for all of your hard work and money spent. I'm surprised that the MP heads were down so much from the HHP and PPP heads. That change in compression, however small, really makes a big difference I guess. I'd bet that Stu's heads would have been right up there with PPP and HHP if it were not for the interference problem. To me it says that any of the four heads would be a good choice.
For probably 8 months I had the converter trying to lock up at the track in 3rd gear @ about 90 + mph. You could even see the dip in rpm during data logs. I called Precision Industries finally and asked about it and they told me the converter should not lock up at wide open throttle and if it was trying to lock up it was something in the computer that was causing it. So I decdided to get another Mopar Performance TCM and after 8 months of having problems it immediatley dissapeared, here are 2 data logs from 1/4 mile runs about a week or 2 apart in the first one you can see the dip in rpm which was always there when the converter was either trying or locking up. Then in the second data log with the Mopar Performance TCM it was completely gone. I have a Precision 3200 stall. Being that the TCM cured the problem the answer must lie in the TCM and programming it Andy diagnosed this problem early on when we couldn't figure out what was happening up in third gear when we were all looking at it as KR and other things
According to PRD website, their heads are $2312.50 for the porting, bigger valves, and titanium retainer option. I think we should list all of the products at their full retail, not street pricing. Maybe the PRD website hasnt been updated?
The price listed to me is what Stu pm'd me with. It sounded real low to me but that's the price I was told.
Great work fellas! the road to more and more power is never-ending. Lol Between the milling disadvantage of the Mopars and the valve train interruption with the PR&D heads, all the heads may have been very close to one another. As it is, the HHP & PPP heads really seem to be very equal. A bit less hp but more tq for HHP and a bit more hp and less tq for the PPP units... this is pretty much a wash. Not to mention one set is hand ported while the other is CNC ported... so much for the devils advocate theory. Lol
