#21
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Re: Pre Turbo Injection - How Much and When to Inject
I don't know. Never put it on a Dyno. The Rover K, 1.8l, is probably in the 250HP range.
It is still knock limited. I believe I know why. Just currently no time taking the head off and in a S1 Elise this is plenty fast, to the degree I don't bother. |
#22
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Re: Pre Turbo Injection - How Much and When to Inject
Still knock limited? But never been on a dyno...
Do you think you could have went past MBT ignition? |
#23
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Re: Pre Turbo Injection - How Much and When to Inject
don't think so. I gain power with every degree advance I add.
We talk 14 deg of advance here with plenty of water/meth and 102 octane fuel on a 4 valve pent roof engine. Without water / meth I am stuck at about 10 degrees. I map myself. I know how power develops as I advance ignition. I also have a J&S safeguard knock control system with a display. Beside this system, knock is also easily audible in a Elise. With both I can map it right to the knock limit myself and observe changes by butt and by data logging. Power changes are also easy to feel as the car weights less than 800kg. I have build the engine with a 1mm copper shim to protect the cylinder ahead against indentation. Rover K heads tend to turn soft over time in high power mid engined applications, especially around the exhaust valve area. This is caused by insufficient coolant flow at idle and low revs after a high load situation.The MLS head gasket seals with a very sharp edge against the hardened alloy cylinder head. I installed a electric water pump and controller to manage the heat in low rev and idle situations. Works a treat. Thing with the shim is that I forgot to chamfer the lower edge of the cylinder bore of the shim. I had specified the shim with a inner bore diameter of 80mm, same a cylinder bore diameter to distribute forces uniformly. the firer ring has a diameter of about 83mm. Normally the shim also has a bore of 83mm. This puts the lower edge of the shim in the quench zone near the head gasket seal area. I believe this exposed edge together with the reduced squish is responsible for the tendency to knock. To fix this I need to replace the head gasket with a N-series head gasket, it employs a flat seal area with a larger surface, and remove the shim. that's it. Compression will still be a reasonable 9.2:1. It is a full day of work. I just don't have the time or motivation to do it in the moment as the car is plenty fast as is. https://youtu.be/onYUHH0muNc?t=25 To put it in perspective: The yellow Elise in front of me is powered by a supercharged Honda K20A2 engine from a Civic Type R with 280HP. On the Radiation straight I just left in it 5th gear. Last edited by rotrex; 01-01-2016 at 08:13 PM. |
#24
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Re: Pre Turbo Injection - How Much and When to Inject
Quote:
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#25
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Re: Pre Turbo Injection - How Much and When to Inject
In Germany we use RON ratings for fuel. MOst stations sell 98 RON (94 US) Octane as the highest, but ARAL/BP sell 102 Octane fuel almost everywhere for 6 cents extra a liter.
102 Octane RON corresponds to a US 98. I use no race fuel. It is just a special pump fuel. Shells offers a 100 Octane, too It is regular pump stuff over here. Stock timing of this engine naturally aspirated is more in the range of 30 to 32 deg ignition advance. The ECU I use is a Emerald K3 from the UK connected to a STACK wideband lambda meter. I run closed loop fueling at all times, even under boost. I have to look for plug pictures, but they have more of a "tan" compared to yours. Tried. An AFR of 13 with 0.6 bars of boost. Worked well, but increased thermal load on track.At 0.8 bar running leaner just makes it more prone to knock and I have to pull timing and I lose power. |
#26
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Re: Pre Turbo Injection - How Much and When to Inject
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I run high 40s igntion advance with lean mixtures 14AFR with 1.4Bar boost 8.5:1 compression. Stock timing is high 20s on aspirated 10.5:1 compression. Here is the plug with threading removed at the above mentioned conditions. This plug was used almost every week with high load during this summer. Last edited by parmas; 02-01-2016 at 07:16 PM. |
#27
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Re: Pre Turbo Injection - How Much and When to Inject
parmas, Why do you run it so lean?
You are missing some power by running it so lean... |
#28
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Re: Pre Turbo Injection - How Much and When to Inject
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Insanely enough I tried 15-16AFR at low boost (1-6psi) but failed as the engine was actually loosing power then. After 6Krpm the engine likes 13.8AFR for the best values.. leaner or richer will loose power |
#29
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Re: Pre Turbo Injection - How Much and When to Inject
Are you sure you're Wideband is accurate?
How did you measure the power change with different AFR? Last edited by Flr Power; 02-01-2016 at 09:20 PM. |
#30
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Re: Pre Turbo Injection - How Much and When to Inject
Are you sure your reference position for ignition timing is right?
Any modern engine won't take 40 deg timing at anything but low load. Typical numbers for NA engines past 3000 rpm and WOT are 30 to 34 deg. Add boost and numbers drop from there. The methanol I use is fuel for fuel cells and of very high purity. Fuel is from a major oil company (BP), sold in their stations from the pump and should not vary that much. It is used as the standard fuel in the DTM racing series in Germay. I won't test it. Not worth the trouble and the expense. It is not sold in barrels in a shop. The timing numbers I run are not that uncommon. The methanol water injection allows for an extra 5 deg of timing. Part of this advance is to compensate for the slower burn speed. A similar engine, but with a turbo without meth water, runs 14 deg of advance at 15 PSI of boost without water. |
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