hellbents10 Posted March 23, 2005 Report Share Posted March 23, 2005 How about 340 g/sec @5900 on a 4.3l v-6 lol. Non-intecooled vortech blower. This is a 98 SS s-10 4.3l auto truck. Link to comment Share on other sites More sharing options...
zippy Posted March 23, 2005 Report Share Posted March 23, 2005 i just ran the boss's truck down the road checking out the tune. it pulled a best of 249gms according to the tech 2. this is a 5.3 with the only other mod being a k and n filter and no airbox ducts/baffles. i assume you guys are using this for your gms-lbs conversion??? gm/sec x .132 = lb/min Link to comment Share on other sites More sharing options...
mcwarren Posted March 24, 2005 Report Share Posted March 24, 2005 Wow, that elevation must really be keeping your power down. I'd be expecting more MAF flow than that. A typical estimate is 10 flywheel HP per pound of MAF flow. Yes it does.....for example I recently made a trip to Fountain Hills, AZ elevation 1500' (near Phoenix) and documented the following. Show Low 6500' = 330 gm/s Fountain Hills 1500' = 384 gm/s We know that every 1000' in elevation change will affect horsepower by approximately 3%, which coincidently is about the change in MAF recorded above. CHP among others state that RWHP on our trucks is approximately equal to MAF in gm/s.....that's about 50 more RWHP. A cheap "dyno" for purposes of evaluating performance changes. As you can see from my example above, 6500 - 1500 = 5000' elevation change X 3% equals 15%, 330 X 1.15 = 379.5 not too far from what I actually saw. There are alot of variables with temp, humidity etc. but interesting numbers. Projecting my 6500' 330gm/s to sea level should get 394.5 gm/s????? Anybody else with altitude vs MAF numbers or MAF vs RWHP? I know this.....my SS is a whole different animal at 1500' vs 6500'...the only salvation is that everything else is slower up here also. Link to comment Share on other sites More sharing options...
BigTex Posted March 24, 2005 Report Share Posted March 24, 2005 I don't change elevations, so I can't help there. But I have logged data in colder temps with higher barometric pressure versus warmer humid temps and low baro. The truck feels slower in the warmer temps, and the MAF flow values show much lower numbers. No air = no power. zippy - that .132 factor is correct. I usually just format my software to display the values in metric or imperial depending on what I'm trying to do. Link to comment Share on other sites More sharing options...
BigTex Posted March 24, 2005 Report Share Posted March 24, 2005 CHP among others state that RWHP on our trucks is approximately equal to MAF in gm/s. Interesting. I'd been taking the pounds/min value * 10 to give appx flywheel HP. Then estimate driveline loss for appx rwhp. 59.9 pounds/min = 454 grams/sec. Along the above logic, thats 599 fwhp = 454 rwhp, for an estimated 24% driveline loss. Sounds good, but the rwhp off grams/sec estimate is too constrained. It doesn't take into account the power needed to drive the compressor on a radix, but not needed on a STS turbo. So a radix truck and sts truck could have the same maf flow value, but the sts would put down more rwhp since its not having to spin the compressor. Link to comment Share on other sites More sharing options...
zippy Posted March 24, 2005 Report Share Posted March 24, 2005 one problem with using the maf gms readings to guess rear wheel hp are the parasitic loss's. as you can see by the numbers the tahoe i scanned were pretty high, but if you dyno'd it they would't run as high as you'd guess from the maf readings simply because the blower takes away a percentage of the power it is making. i believe the tahoe for example was around 420 or so gms at peak. when we first got it together and took it to the track it was chassis dyno'd and made 335 if i recall to the tires. we had a few issue's at that point to address, but with less than 50 miles on the setup it wasn't all ironed out. even after we were able to get the majority of the tuning issue's fixed it probably wouldn't have put down more than 355 to the tires yet it showed 420 at the maf. had it pulled these numbers naturally asperated i'd bet the theory would have applied to this, but as you can see due to the blowers natural parasitic drag it was considerably less. Link to comment Share on other sites More sharing options...
mcwarren Posted March 24, 2005 Report Share Posted March 24, 2005 Sounds good, but the rwhp off grams/sec estimate is too constrained. It doesn't take into account the power needed to drive the compressor on a radix, but not needed on a STS turbo. So a radix truck and sts truck could have the same maf flow value, but the sts would put down more rwhp since its not having to spin the compressor. BigTex, you are absolutely correct. My bad, I should have stated that the CHP article/statement was about the Radix SS and might not apply to other configurations. MAF to RWHP may only apply to the Radix SS, but everyone of us can use MAF to verify performance changes to their SS when carefully documented variations in elevation, temp, barometric pressure and humidity are taken into account. It would also seem to make sense that the FWHP of the Turbo engine would be more than the FWHP of the Radix engine with equal MAF, so I wonder if the "pounds/min value * 10 to give appx flywheel HP" would be equal for the Radix vs STS engine. Anybody else have MAF to RWHP numbers on an SS and if so, what are you running? Link to comment Share on other sites More sharing options...
BigTex Posted March 24, 2005 Report Share Posted March 24, 2005 MAF to RWHP may only apply to the Radix SS, ... Funny thing. The grams/sec was very close to my estimated pounds conversion, but I do have a radix. Say I see 60 pounds / 454 grams at 5000 rpms. Thats 600 flywheel hp, but I take out 50 hp for compressor drag for 550, then pull out 20% drivetrain loss for an estimated 440 rwhp. Link to comment Share on other sites More sharing options...
zippy Posted March 24, 2005 Report Share Posted March 24, 2005 it sounds like oddly enough for an SS the system works. Link to comment Share on other sites More sharing options...
hellbents10 Posted March 24, 2005 Report Share Posted March 24, 2005 It was close for the s-10 too. On the dynojet with the first tune it put down 272 to the tires then on the mustang dyno it put down 310 to the tires with a new tune. TJ Link to comment Share on other sites More sharing options...
hellbents10 Posted April 1, 2005 Report Share Posted April 1, 2005 I know the MAF is not supposed to interpert values this high but....We seen 63lbs/min on Vince's truck with the 3" pulley on the radix last night. Link to comment Share on other sites More sharing options...
zippy Posted April 2, 2005 Report Share Posted April 2, 2005 something kinda odd if someone wants to look at it. i have a log of vince's truck pulling 63.46 lbs min. at the maf. in the chart and gauge sections it just maxes, but you can see it in tables and if you follow the topped out line in chart display. once you get past 60 it just continue's to read it. if i could figure out how to make it display on here i will unless someone else wants to try it and i can send them the file. Link to comment Share on other sites More sharing options...
zippy Posted April 3, 2005 Report Share Posted April 3, 2005 any thoughts on this richard? Link to comment Share on other sites More sharing options...
BigTex Posted April 6, 2005 Report Share Posted April 6, 2005 Yes, I would like to see this. What software are you using? Do your logs have MAF Hz values? The PCM table stops at 12000 Hz, which is 59.9 pounds of air for a stock MAF. Either his tables have been altered for some reason, or the software is "guessing" at the airflow values above 12000 Hz. When I'm logging, my EFI Live software can show the MAF Hz (RAW data) values and the MAF airflow (calculated data from the PCM tables). When I reach the PCM limit, I can log MAF Hz values above 12000 because that comes directly from the MAF sensor. MAF airflow however stops at the 59.9 pound limit since its a calculated value and there are no references in a stock MAF table for anything above 59.9. Link to comment Share on other sites More sharing options...
zippy Posted April 6, 2005 Report Share Posted April 6, 2005 i'll see if i can take a picture of the screenshot or something. i can e-mail you that log also. if you find someone with hptuners you can watch it. i rather thought it was odd. Link to comment Share on other sites More sharing options...
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