SixSeven
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« Reply #105 on: March 04, 2014, 12:48:56 PM »
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If you want to make power you need to drop CR.
^This. I think there is quite a bit of misinformation that circulates various forums these days concerning the levels of power that are supposedly made with stock compression ratios. I'm not saying 300-400hp isn't possible running 9.5:1 combined with a highly knock resistant fuel and/or some water-meth injection, but if you're looking for those figures on pump gas without a lot of headache you'll be dropping your CR. It's interesting to see people's aversion to dropping their compression ratios in forced induction applications. You'll certainly take a hit on your freeway fuel economy, but you're going to see gains virtually everywhere else. I wonder if it stems from carry-over from the NA crowd where high compression and crazy high rev-limiters make power. |
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nyet
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« Reply #106 on: March 04, 2014, 03:55:25 PM »
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I wonder if it stems from carry-over from the NA crowd where high compression and crazy high rev-limiters make power.
Absolutely. They have no other alternative, so it became "conventional wisdom" that if you do a motor rebuild, you want to use some crazy high CR and/or never lower it. |
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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SixSeven
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« Reply #107 on: March 04, 2014, 06:06:24 PM »
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Well, if that's their cup of tea they can always run straight toluene in the thing.
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carsey
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« Reply #108 on: March 07, 2014, 08:51:20 PM »
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I know both nokiafix and ibizacupra and both are getting some of the best results from OEM turbos ive seen here in the UK.
What grade fuel do you guys use? Over here in UK we are using 98-99 octane fuels which could be a bit higher than other EU countries?
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prj
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« Reply #109 on: March 08, 2014, 01:17:02 PM »
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No, UK fuel is nothing special.
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carsey
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« Reply #110 on: March 09, 2014, 01:28:41 AM »
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Figures must deceive the facts then  |
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bomby
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« Reply #111 on: March 10, 2014, 01:10:40 PM »
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i always use 98 octaine "best" you can get here at the pump like Shel V-power (98) or Total or Q8 or the cheaper fuel near my home "maes" but still 98. And they give me all the same beheivior in Knock retard on the ingition. But when i drove trough Germany and Austria there they have "BP 102" octane and "shell 100-102" then there the care felt a bit beter litle more power en agresive on top  Shame whe dont have those fuels in Belguim |
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leolux
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« Reply #112 on: March 14, 2014, 06:03:16 PM »
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If you plan only run with PumGAs go down with compression!!!
Look my Car Stock 8.9 Compression with 102 ARAL (BP) GAS... Verry Bad Ignition Timings. This run are on dyno, on street i dont can drive above 13 degree.. I have planed to run this car with e85 it was only a test how much i can go with PumpGAs
Leo
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Awaken
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« Reply #113 on: September 04, 2022, 02:09:09 AM »
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This topic is such an old gem. Here's some input from me, hope someone will find it useful. Comments are welcome.
The car is a 2 litre stroker from a 1.8T BAM, ME 7.5. The crank and pistons are from 2 TFSI. CR is about 9.8-10:1. GTX3071R Gen 2 @ 1.7-1.8 Bar reached at 4200 rpm, 0.5 bar at 3000 rpm. I run a 4 bar MAP, so the readings are little off, don't get confused by the log. The cams are 'aggressive' stock cams from an AGN NA motor. There is no CAM overlap (VVTI swtiched off completely).
The graph is with Bardahl Octane Booster, so 0 timing pull from KR. If I run just pump gas I get about 1.5-3 degrees timing pull from KR.
The injectors are bosch 630cc @ 3 bar, but I am maxing the out as you can see.
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« Last Edit: September 05, 2022, 12:47:04 PM by Awaken »
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Awaken
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« Reply #114 on: September 04, 2022, 01:13:39 PM »
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....
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prj
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« Reply #115 on: September 04, 2022, 01:36:09 PM »
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Run that at WOT for any significant amount of time and you will drop an exhaust valve due to the insane EGT.
That timing is not safe even with octane boosting, and on pump fuel it's even worse. CR needs to be 8.0 for pump fuel and this turbo or you need E85.
Let me guess, no EGT sensor? Or not flooring it for longer than 5 seconds at a time?
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« Last Edit: September 04, 2022, 01:46:03 PM by prj »
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Awaken
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« Reply #116 on: September 04, 2022, 02:11:46 PM »
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Let me guess, no EGT sensor? Or not flooring it for longer than 5 seconds at a time?
4 EGT sensors, one on each cylinder, but yes not flooring it for too long. Temp goes to about 860 C on a single WOT pull, will probably go higher due to temp accumulation if I do many without cooling down. Valves are Supertech, so hopefully they will hold. Here's a log on pump gas only. I decided to bump up the ignition timing with the octane booster to decrease the EGT. Why don't you consider it safe when it doesn't knock and EGT is lower with higher timing? What timing is considered safe with this setup? |
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« Last Edit: September 04, 2022, 02:14:01 PM by Awaken »
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prj
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« Reply #117 on: September 04, 2022, 02:21:56 PM »
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860C on single WOT pull of what 4-5 seconds? And it's not in the log anyway, so whatever.
You have random screenshots that don't show time, no csv's.
I'll let you drop the valve and trash the motor as a learning experience.
Maybe you'll build it with the correct CR after.
Your supertech valves have nothing to do with the fact that the exhaust valve will drop from it's seat, that's usually what goes first on 5 valve heads with too high egt. The motor is trash after of course, usually the turbine wheel goes as well.
Or you will just melt a piston.
Nothing you posted here is safe. It's actually a very good example of why correct CR needs to be used.
Your engine is only good for E85 or MS109.
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Awaken
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« Reply #118 on: September 04, 2022, 02:52:49 PM »
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I'll let you drop the valve and trash the motor as a learning experience.
Maybe you'll build it with the correct CR after.
Your supertech valves have nothing to do with the fact that the exhaust valve will drop from it's seat, that's usually what goes first on 5 valve heads with too high egt. The motor is trash after of course, usually the turbine wheel goes as well.
Or you will just melt a piston.
Been there, but none of that goes first. What goes first is the turbine wheel heat shield. Opens like a can cover and the rest is history. I've had motors that held up at 1000C without too many upgraded parts inside, so I consider 860 a success. This setup was little experimental and it was too late to change so we closed with this CR. What EGT do we consider safe? Lowering boost is always an option. 860C on single WOT pull of what 4-5 seconds? And it's not in the log anyway, so whatever.
This is actually a WOT 4th and 5th to do 100-200km/h, 860 is at end of 5th @ 200km/h (my gears are short). The stock EGT is out, so it's not in the log indeed. |
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« Last Edit: September 04, 2022, 03:10:07 PM by Awaken »
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fknbrkn
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« Reply #119 on: September 04, 2022, 09:20:29 PM »
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Thats pretty good timing for such a high cr even on a pump gas
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