368 HP dyno, 21 PSI Stock Turbos & motor
12-22-08, 11:28 AM
#51
arghx did you notice the stock basemap timing in the PFC? P20 is around 20 psi on the stock map by going off the offset/scale. (even though the map sensor only reads to about 17.5 psi) Anyway the IGL timing dips down to 3 degrees advance in the peak torque area, with a split of 4. Dangerous split, but very conservative timing for that boost. I would expect something more like 10 degrees advance at 20 psi with a 12 degree split. If Tom was to only change the split his power would probably go down with such a low advance.
It's kind of strange how the PFC timing is. I wonder if it's possible to run closer splits with more conservative timing, and what the effect and difference is on power/safety. What most of us do is run a higher IGL and then go with a bigger split to keep it safe. To me it seems that both ways are effectively doing the same thing just in different ways. But maybe this isnt the right place for this discussion, so later ill start a thread in the PFC section about it.
It's kind of strange how the PFC timing is. I wonder if it's possible to run closer splits with more conservative timing, and what the effect and difference is on power/safety. What most of us do is run a higher IGL and then go with a bigger split to keep it safe. To me it seems that both ways are effectively doing the same thing just in different ways. But maybe this isnt the right place for this discussion, so later ill start a thread in the PFC section about it.
Last edited by tom94RX-7; 12-22-08 at 11:31 AM.
12-22-08, 11:30 AM
#52
I was thinking maybe mine isn't making as much power because of low compression?
I have also thought that it seems the only power advantage was from the extra boost. The low boost non-seq. graph is weird cause the power curve is different than the others, it may not be right, maybe the boost controller didn't work right or something, it was the first pull on the dyno, perhaps another pull would have been different at that boost level. And I didn't watch the boost gauge, I think it's possible it may have only been at 14-15 psi at the max power shown on the graph, cause max boost should have been at around 5500-6k rpms and then it always falls off like 2 psi, cause it always has a boost spike when the boost hits, and it said max boost was 16.
comparing the low boost non seq to the old seq run, I think it was probably more like 2.5 psi difference, but again I should have done two pulls on the dyno at that low boost. My boost controller acts funny sometimes during the first pull, like I have to toggle it between low and high at least once after starting the car or else it will limit the boost for some odd reason, I did that before the dyno pull but it's just weird that power curve is so much different than the higher boost settings.
I have also thought that it seems the only power advantage was from the extra boost. The low boost non-seq. graph is weird cause the power curve is different than the others, it may not be right, maybe the boost controller didn't work right or something, it was the first pull on the dyno, perhaps another pull would have been different at that boost level. And I didn't watch the boost gauge, I think it's possible it may have only been at 14-15 psi at the max power shown on the graph, cause max boost should have been at around 5500-6k rpms and then it always falls off like 2 psi, cause it always has a boost spike when the boost hits, and it said max boost was 16.
comparing the low boost non seq to the old seq run, I think it was probably more like 2.5 psi difference, but again I should have done two pulls on the dyno at that low boost. My boost controller acts funny sometimes during the first pull, like I have to toggle it between low and high at least once after starting the car or else it will limit the boost for some odd reason, I did that before the dyno pull but it's just weird that power curve is so much different than the higher boost settings.
Khris
12-23-08, 12:34 AM
#54
yeah tom you need to be running about 10* leading timing and about a 12-14* split at 20psi.
i've already posted that i wouldn't be running that boost on pumpgas unless you're spraying your methanol ontop of it.
if i were you i'd be running 15-16psi with 15* leading timing and about a 10* split.
i've already posted that i wouldn't be running that boost on pumpgas unless you're spraying your methanol ontop of it.
if i were you i'd be running 15-16psi with 15* leading timing and about a 10* split.
12-23-08, 09:19 AM
#55
I don't think your compression numbers are really that low. I don't think the power output difference would be alot from 90 - 115 compression. That's just a guess though considering most engines with similar setups produce similar power and I'm sure the compression numbers would be a bit different depending on the age of the engine and whether used or new housings are used in a rebuild.
For timing, I've posted general guidelines before that might be a bit more detailed but.... Timing goes up with rpm and down with boost. About 1 degree per 1 PSI. The stock PFC scaling is about 3 Psi between P rows after P15 (with stock scale). P20 is usually around 20 psi, but the PFC scales are not exact. Generally don't exceed about 15 degrees at 15 psi in the high torque areas for a stock ported engine. Peak torque is usually between P14-P16 after that you can raise the timing again a few degrees to redline. So going with a 1 degree drop per psi at 20 psi you would be at around 10 degrees leading. I'm not experienced in tuning for boost higher then around 15 psi so you might do more research for running the high boost.
Running lower, or closer split is similar to advancing timing and increases combustion chamber pressures. Split should be anywhere from 0-3 degree split in vacuum (P10 and less) Then taper up with boost, going from about 4 degrees up to your highest split of between 12-15 degrees. It can also taper with rpms. So it will look something like 0-3 split P1-P10, then P11 will be 4 degree split, P12 = 6, P13 = 8, P14 = 10, P15-P19 =12 and P20 14. RPMs will taper going from their highest split in rows N9-N20, and everything from N8 down will taper about 2 degrees per N row to your 3 degree split.
The best thing to do is get as many maps you can, and study them. Especially people running similar setups as you. Just keep in mind that just cause someone else did it, doesn't mean it's correct. I also recommend you getting either a dataloggit, or at least the software so you can enter all your IGL timing in, then when you do the IGT you can check the box "Display split" Enter all your split levels in, and uncheck "display split" so you can manually enter the numbers into your commander. Otherwise you will have to do the math and it will suck ***.
For timing, I've posted general guidelines before that might be a bit more detailed but.... Timing goes up with rpm and down with boost. About 1 degree per 1 PSI. The stock PFC scaling is about 3 Psi between P rows after P15 (with stock scale). P20 is usually around 20 psi, but the PFC scales are not exact. Generally don't exceed about 15 degrees at 15 psi in the high torque areas for a stock ported engine. Peak torque is usually between P14-P16 after that you can raise the timing again a few degrees to redline. So going with a 1 degree drop per psi at 20 psi you would be at around 10 degrees leading. I'm not experienced in tuning for boost higher then around 15 psi so you might do more research for running the high boost.
Running lower, or closer split is similar to advancing timing and increases combustion chamber pressures. Split should be anywhere from 0-3 degree split in vacuum (P10 and less) Then taper up with boost, going from about 4 degrees up to your highest split of between 12-15 degrees. It can also taper with rpms. So it will look something like 0-3 split P1-P10, then P11 will be 4 degree split, P12 = 6, P13 = 8, P14 = 10, P15-P19 =12 and P20 14. RPMs will taper going from their highest split in rows N9-N20, and everything from N8 down will taper about 2 degrees per N row to your 3 degree split.
The best thing to do is get as many maps you can, and study them. Especially people running similar setups as you. Just keep in mind that just cause someone else did it, doesn't mean it's correct. I also recommend you getting either a dataloggit, or at least the software so you can enter all your IGL timing in, then when you do the IGT you can check the box "Display split" Enter all your split levels in, and uncheck "display split" so you can manually enter the numbers into your commander. Otherwise you will have to do the math and it will suck ***.
Last edited by Dudemaaanownsanrx7; 12-23-08 at 09:33 AM.
12-24-08, 02:11 PM
#56
Apparently, few but Tom94Rx-7 have the ***** to run 20psi on a stock motor, straight pump gas, and twins like that. So we're all being armchair tuners here in terms of what timing to run. Nobody here can physically examine his plugs, nobody here has an EGT gauge in front of them. How many people here have ever tuned a car on stock twins at 20psi? I know I haven't. But I do know that his car hasn't blown up yet despite dire predictions, and I think the PFC leading map is partly why.
If the leading map has worked this long, why not stick with it? With all the heat being thrown out by those turbos, I think the 3-7 degrees of the PFC basemap is just fine, and is probably why his motor hasn't blown up yet. Adding split will increase the safety some and maybe cost him a couple HP--which is always preferable to blowing the motor. And who cares if the dyno numbers are lower than somebody else's setup? Greed blows motors. Ask me how I know. His timeslips are better than a lot of cars with 400+rwhp, and the car seems to still be responding to the extra boost.
And for what it's worth, I've seen maps for single turbos Supras running that kind of timing on straight pump gas and high boost like that.
Pull the plugs out and check for detonation. If it looks ok just keep rolling. Maybe smooth the timing out a bit but do NOT advance it!!!
If the leading map has worked this long, why not stick with it? With all the heat being thrown out by those turbos, I think the 3-7 degrees of the PFC basemap is just fine, and is probably why his motor hasn't blown up yet. Adding split will increase the safety some and maybe cost him a couple HP--which is always preferable to blowing the motor. And who cares if the dyno numbers are lower than somebody else's setup? Greed blows motors. Ask me how I know. His timeslips are better than a lot of cars with 400+rwhp, and the car seems to still be responding to the extra boost.
And for what it's worth, I've seen maps for single turbos Supras running that kind of timing on straight pump gas and high boost like that.
Pull the plugs out and check for detonation. If it looks ok just keep rolling. Maybe smooth the timing out a bit but do NOT advance it!!!
Last edited by arghx; 12-24-08 at 02:34 PM. Reason: if it ain't broke don't fix it
12-24-08, 05:42 PM
#57
yeah tom you need to be running about 10* leading timing and about a 12-14* split at 20psi.
i've already posted that i wouldn't be running that boost on pumpgas unless you're spraying your methanol ontop of it.
if i were you i'd be running 15-16psi with 15* leading timing and about a 10* split.
i've already posted that i wouldn't be running that boost on pumpgas unless you're spraying your methanol ontop of it.
if i were you i'd be running 15-16psi with 15* leading timing and about a 10* split.
12-24-08, 05:47 PM
#58
My horsepower seems really low at 15-16 psi compared to others thats why I am wondering if my motor is losing power cause the compression is not that great. I could try using excel or if I can download the free datalogit software somewhere that would be good. thanks guys
12-24-08, 05:57 PM
#59
My spark plugs did look good when I just took them out to do the compression test. I think it would be a good idea to get a egt gauge that hooks up directly to my plx r500 wideband and then I can do some testing with small changes to the timing and datalogging. Also my air fuel ratios being tuned well and constantly observed is I think another reason my my motor still runs good.
12-24-08, 11:54 PM
#61
My horsepower seems really low at 15-16 psi compared to others thats why I am wondering if my motor is losing power cause the compression is not that great. I could try using excel or if I can download the free datalogit software somewhere that would be good. thanks guys
If you're interested I can get a zip file together of a bunch of the maps I have found around the web, although most of them are maps of single turbo cars.
Keep in mind when comparing maps that the scale and offset might not be the same from map to map, which means the boost levels at certain P rows may not be the same, the rpms might even be different but usually the N rows are close enough that they dont make a huge difference.. For instance my P20 row is 21853 scale instead of the stock 24000, my p20 is 17.5 psi instead of 20.XX, so if you were to compare my map to a stock map you would need to look at my p20 and probably the stock maps p19 for the boost levels to be close. So always pay attention to what the scales of each map is, and make sure you are not comparing them in the wrong areas.
12-27-08, 02:48 PM
#63
My horsepower seems really low at 15-16 psi compared to others thats why I am wondering if my motor is losing power cause the compression is not that great. I could try using excel or if I can download the free datalogit software somewhere that would be good. thanks guys
Bingo. Having really low compression is almost like having a really really low compression ratio. Refreshen your engine and you should see an improvement in the 15psi range.
09-21-09, 12:12 PM
#65
So my motor finally blew, well half of it, rear rotor has no compression at all, front rotor still has 90 psi, same as last tested. I was drag racing, then I went to get more gas, ran normal when I went wot on way to gas station. Then on the way back up the hill after getting gas, went wot in 3rd gear and at about 6k rpms it just suddenly lost power, and would barely run and would not make it up the hill. So now it barely runs, its really hard to start like when its flooded from the bad coolant seals which sometimes let coolant into the rotor housings, and I have to keep the gas on some to keep it running. Obviously I know it all needs rebuilt, and I will try to do this myself, and get a dvd rebuild video. I have been dealing with bad leaky coolant seals for a long time and after a couple runs at the track before it blew, it was loosing alot of coolant in between runs, although it did not have any big problems starting. Peak boost was 20 and it was probably holding around 18 psi. My eyes were on the wideband when it blew, 11.3 11.4 which is always what it runs, no leaner than that, mostly richer than that.
09-21-09, 01:51 PM
#67
ya the engine definately had a good run, or lasted alot longer than you would think given all the racing and high boost. Also the rear compression was down around 80 so it has been in that category of could blow at any time for a while now. So I am assuming it blew from old age and running it very hard. So do you think my turbos may have got destroyed from apex seals? I still got my old turbos. I cant really afford to spend much money on this so I should do it as cheap as possible but still replace everything needed, and I am guessing the rotor housings will need to be replaced or should be to get better compression, maybe even the rotors. So i dont know about getting them ported.
09-21-09, 03:54 PM
#70
j/k much respect for the abuse the little 13BREW has put up with from this guy and the tune/driving that went with it, it was truly impressive IMHO. Hey Tom, don't rule out a bad tank of gas as a possible cause of death (probably more technically correct to say, "possible contributor to death"), I always wondered if there was a cheap/easy way to test the octane rating of the fuel. Also, did you feel/hear any knocking from the motor before it went? Also, what were the temps outside when it went and what were your indicated IATs. Keep us posted and post lots of pics when you get the motor apart!
09-21-09, 04:32 PM
#71
Ya I'm sure some luck has helped haha, but mostly this forum and all the great info that allowed me to do what I did with the car. I wanted to run 10s so bad with the original motor and stock twins, I got real close with the sequential twins (11.16), then went non-seq and got even closer (11.08), but that was with my clutch slipping, so I got a new clutch and then next time out I didn't drive perfect, got two runs then it rained, so that sucked, then next time out I dumped the clutch too fast (not trying to burn up the new clutch by letting it slip like I usually do) and the rear diff. broke, so then I just fixed that with a T2 diff. and next time out I didn't drive great or launch good enough, then the motor blew, so I have had alot of bad luck lately. I should have ran at least a 10.9 if my clutch wasn't slipping the one day, the clutch didn't fully grab until I hit 3rd gear but still did 11.08, then the next run it didn't fully grab until 4th gear and still did 11.16 (I was watching my rpm gauge and seen it at like 7-8k the whole way down the track), and you should have seen the clutch, you wouldn't think the car was driveable with the clutch that came out of it lol.
I had a 1/4 tank of gas in it, my last run I launched good and it hesitated at about 50ft from not enough gas in the tank, it ran good the rest of the way down the track. So that's when I realized it was only at 1/4 tank and needed more gas, went down and got 3.5 gallons, then going back to the track it blew. So I doubt it was the gas unless it was extremely bad gas but I would say not likely.
I did not feel or hear anything bad at all, the car just suddenly stopped accelerating even though I was still WOT haha. It was about 60 degrees out, getting chilly. Intake air temps were probably around 25-30C, nothing high. I will keep you posted with pics, I may start tearing it apart today to pull out the motor.
Thanks.
I had a 1/4 tank of gas in it, my last run I launched good and it hesitated at about 50ft from not enough gas in the tank, it ran good the rest of the way down the track. So that's when I realized it was only at 1/4 tank and needed more gas, went down and got 3.5 gallons, then going back to the track it blew. So I doubt it was the gas unless it was extremely bad gas but I would say not likely.
I did not feel or hear anything bad at all, the car just suddenly stopped accelerating even though I was still WOT haha. It was about 60 degrees out, getting chilly. Intake air temps were probably around 25-30C, nothing high. I will keep you posted with pics, I may start tearing it apart today to pull out the motor.
Thanks.
09-21-09, 05:27 PM
#74
I can see that being possible, but That has also happened a few times in the past. I have been wondering if it could have blown from some sort of sudden water seal failure cause it was losing more coolant than usual in between runs, I had to actually add coolant before each of the last two runs, enough leaked out causing the low coolant buzzer to come on, more than usual, the aluminum AST was almost empty. and it was pretty hot when I got to the track, 235F 111C for a few minutes before getting into the staging lane and shutting it off. It got this hot a couple times on the way to the track but did cool back off to around 90C.
