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#61
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In point of fact, the process has in the main, been limited to hobby applications; several concerns over many years, having promoted the idea along with sets of components. I have friend who spent untold hours, before disbanding such a project, as have many others. A major problem still to be solved, involves a reliable arrangement which will automatically shut off the water, shortly before each and every time the engine is stopped. Without this feature, residual moisture has been proven to cause real damage, through corrosion. Rings and valves in particular being badly affected. Harvey, all here will be interested to learn as to exactly how you overcame this problem, even though it has perplexed and defeated others.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#62
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I run water injection. It comes on when boost is sensed. It is not going to "cure" detonation. Only reduce it. It might be possible to tune the car with forged pistons at 10:1 compression and low to medium boost. But why would I not drop to 8.5:1 when I'm installing custom pistons. It would be a great experiment, but a bit too expensive.
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
#63
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Are you still running the magnaflow setup or did you change it to a true dual now?
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Tim 92 Liquid Silver SVX 5MT 2009 BMW Z4 (Gone) 2012 Camry V6 SE |
#64
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
#65
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nah Tim... its still the magnaslows... I will be whipping up a new system in the spring hopefully.
Tom |
#66
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The Water works.
Sorry Tom,
I am not just directing this at you only. I know you will do what ever you want, I am thinking of other people that want to try, or are trying to force induct the EG33. There is a difference in the way combustion is handled between the Naturally Aspirated, and Supercharged engine. The big difference is knock, on our engine in NA form, at full throttle 5000 rpm, we have a combustion chamber trapped pressure of 1.636 bar/24psi, the temp of the charge is 119*C. The ignition advance in this case would be about 35/37*BTDC. and the maximum pressure developed in the chamber during the burn is 71.4 bar/1050psi, and will occur at 17* ATDC. The combustion chamber and piston crown temp will be 358*C. Now if we run a inlet maifold pressure of 1bar, the above pressures and temperatures will double, and the burn time will almost halve. We still need the maximum pressure to be at 17*ATDC, so we will have to start the burn later, by reducing the ignition advance, to have the maximum pressure arrive at the same 17*ATDC. Now this can be done by dynoing the engine and setting the timing advance to suit each operating condition for Air flow X rpm. But, it only takes a load of bad fuel, a very hot air day, or a slight engine overheat, valve bounce, exhaust backflow on ovelap etc. for it to step out of the mapped conditions line, and detonation takes it all out. When detonation takes place, in an engine operating under these boosted conditions, it is unfortunately too late to save the engine. The same knock that the sensors hears, breaks the top rings, or in this case also shearing off the second ring land. When the engine has this much pressure in the chamber, there is no second chance, like there is, when it is NA and the detonation pressure is much lower. Detonation, is the spontaneous, uncontrolled combustion, of part or all of the compressed charge, after the spark has started a burn. What happens is the spark lights the charge, the flame front burns out away from the plug, As the flame front advances across the chamber, the gas that is furthest away from the plug in the exhaust side, is increasing in temperature, from the radiated heat, and pressure from the expanded gas already burnt. This gas reaches its flash point, and explodes, this sudden rise in pressure, hammers the top ring, the piston and the bearings. When detonation is on, the piston usually breaks, and the rod is let go, to do its own thing. We can do a number of things to prevent this. Use a fuel that can withstand the pressure and temp (higher octane), because of its higher flash point, We can reduce the temperature of the gas charge with an intercooler. Or combustion chamber, using a fuel like Alcohol. Or we can use water injection. Water injection is not a new band-aid, it was used extensively in the development of aircraft engines during the 2WW. In Sir Harry Ricardo’s Book “ THE HIGH SPEED INTERNAL-COMBUSTION ENGINE” That every body has on their shelf. (under ’Supercharging’ or Google supercharge+water+injection.) He relates the development of a supercharged aircraft engine that reached detonation at a BMEP of 168psi. Fuel enrichment was increased ( up to 60%) to allow further boost, to achieve a BMEP of 238 psi. when detonation again occurred. A fine stream of misted water was then sprayed into the inlet, and the boost pressure increased till detonation occurred, to reach a BMEP of 290 psi. In the example that I did on the sidevalve. I had detonation starting at 8psi. This would have been my limit, without dropping the compression ratio,( which reduces the off boost performance ) or using a better fuel.(too dear). But with the water starting at 7psi, I was able to increase the boost to 14psi. without any risk of detonation. You can introduce the water in a few ways, mixed with the fuel(using Acetone), but as it is only needed when it is on boost, its is better to introduce it into the inlet tract, to cool the charge, and the combustion chamber, the resultant steam suppresses detonation. There are a number of water kits on the market, I would look for one that can spray the water, proportional to boost, as too much water will drop power. You just need enough to suppress detonation. The best would be able to use the blower’s by-pass, to control boost at low rpms, and proportionally spray water to suit the boost. The way I did it back then, was to have the manifold pressure applied to a container of water, when the boost reached the 2psi, it opened a one-way valve to flow to the carb, proportionally to the boost pressure acting on it. When the engine was on vacuum it sucked water up from a tank in the boot to top up the front tank. Oldies will recognise this as the ‘Vacuum fuel tank’ that we used to bring fuel up to the engine in the 20s. The numbers used in this post, are for example only, they are in the range, for these conditions. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#67
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One of the axis of the timing maps is load. Load whether measured by manifold pressure or calculated from the mass of air measured and rpm equates to the same thing. Mass air measurements are more accurate actually. There do seem to be some mechanical limitations to running higher boost. Whether just because of 150,000 miles of wear or because the ring set up isn't optimal for forced induction or a combination of both there is obviously a problem with blow by.
We can probably improve the tuning at higher loads as well. My personal feeling is that these 150,000 mile factory engines obviously aren't happy with a lot of boost so we aught to go ahead and build the engines appropriately for what we want...which we are doing...and to do our higher load tuning on these engines. It seems kind of pointless to try and run high boost on worn out motors. It will be easier for me to tune the high loads when I don't have exhaust flow problems and fluttering rings confounding my measurements anyway. |
#68
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Engines
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
#69
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So when we ordering some parts already???...... Money + Pocket = 5 alarm fire. |
#70
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Tom, how did you destroy that engine??
Also, I am curious (probably has been answered already though ) How much power can that supercharger kit produce reliably on an engine with around 100k miles??
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2020 Subaru Outback Touring - Wife's first Subaru 2005 Volvo V70R - 5-cylinder love! :Heart: ** SOLD **1998 Subaru Legacy 2.5GT Wagon - MOST RELIABLE car I've ever owned ** SOLD **2006Subaru WRXSTi (Former "Boxer4Racing.com / Continential Tire" STi) - Built EJ22t block / EJ207 JDM STi "big port heads" - 9,000rpm MONEY PIT!!! ** SOLD ** 1995 "Tree-Hugger Green" SVX L AWD(5 MT) --- "Gumby" 130K miles #399 in MY95, my original love... |
#71
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I'm getting 229whp and 243wtq at a safe 9lbs of boost. with 68K miles on it.
The higher numbers are Toms car at 12lbs boost and the lower is mine with 9lbs boost. The main difference between Toms car and mine is that I was running 2 1/2in duals all the way out. |
#72
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These guys obviously know what they are doing, as per the evidence from them confirming a sound logical approach.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#73
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yes.....that logical approach thing..... im sure someday i will run that route, but its just too much damn fun grabbing a 12 pack and a tig!
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
#74
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#75
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Well I'm back now. I'm guessing my sample piston is waiting for me at the dealership so we can order pistons this next week. I'll probably be getting my cams ground next week too but I won't be ready to order the cam package for others until after I've gotten my cams ground and am ready to order the valves. I have to actually get the cams ground before I know exactly how much the base circle is reduced so I can order the valves. I already have several sets of springs in stock.
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