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Dave,
The standard Evo aftercooler (good grief , what have I started is efficient , the most likely reason 4 the lack of evident upgrades is that it wud require modifications 2 the front spoiler 2 install a cooler (ah , thats convenient) with a larger surface area.
The HKS etc r not enuf of an improvement, if any, 2 justify the cost of them , wot we need is a cooler with a significantly larger surface area....watch this space :) Scoobys and the like get bigger benefits from cooler upgrades because the standard 1's are mounted in a bad location and r small.
 
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Discussion Starter · #22 ·
Evoboy,

Simple enough when it's explained! Sounds like there's a good opportunity for some tuning company to develop a part that would make a real difference at a reasonable price if they can come up with the right design. Perhaps it's possible to make a deeper or denser intercooler? But if the air is cooler, does that increase the pressure or just increase the air density which is what I think it would do? Sounds too good to be true, the cooler the air the denser and more power, but what are the downsides - the need for more fuel than the car can provide for example, so uprated fuel pumps, ecu's, etc?

Dave
 
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Discussion Starter · #23 ·
Yep, just as I thought (and HH6 has already confirmed), the engines I was referring to (automotive, industrial, marine etc turbo diesel applications) do use the engine cooling system to cool the charge air (We use air to air CAC's more for better emissions nowdays though) . I know that alot of our Customers refer to this set up as an intercooler but I think I 'll quietly back away from this debate now.
 
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DaveG,
Now you have jumped to the next Chapter in 21st Century Performance - 'Intercooling' (only 17 pages on this topic though! ;)

Intercooling has two distinct advantages on turbo charged cars:
It cools the heated air from the turbo and thus the air becomes more dense. Its the mass of the air that is breathed by the engine that determines the power not the volume. Cold air of a fixed volume has greater mass than warm air of the same volume.
If an engine is breathing hot air then there is more likelyhood of detonation. Obviously the cooler the air the less likely detonation will occur.

Disadvantage:
Boost pressure will drop slightly due to the restriction of having to pass through the intercooler.

The standard Evo intercooler can be upgraded but a more cost effective starting point to improve efficiency is to sort out the factory intercooler spray! I don't know about other peoples Evo's but my intercooler spray is a bit of a joke. Sure it sprays onto the intercooler but the windscreen washer type nozzles are not exactly brilliant! Get some decent sprayer nozzles (garden or industrial sprayer) that produce a wide angle fine atomized spray that can cover all the intercooler and you will have a very cost effective upgrade. Blocking off the Radiator spray nozzles (E5/6) may also help to improve the intercooler sprays efficiency by boosting the sprays pressure.
As I have said in previous threads you are better off chucking a bucket of water over the intercooler before setting off than relying on the spray!
You could also wire up the intercooler spray to work automatically when needed as its a fairly simple job. Perhaps I will have a go :)
 
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Discussion Starter · #26 ·
What is this intercooler/aftercooler b******t all about!!! You pedantic b*****ds!!! Who gives a f**k what we call it we all know what people are talking about when they say intercooler.

OK - now that's off my chest - what you guys all need before you go buying huge intercoolers is a measurement of the air temperature entering the inlet manifold. You should be aiming not to exceed 45-50 deg C. Too cold and fuel atomisation suffers as droplets start to condense in the intake. Too hot and pre-ignition becomes more likely. A multimeter with a thermocouple input does the job.

What you also need before you blow your turbo to pieces is a compressor map for the standard td05-16G6 turbo fitted to evo's 3-7. (1-2 were td05-16g). Note that the turbos on evos 4-7 all spin in the opposite direction to those on the early evos.

I finally found 16g and 16g6 compressor maps the other week. It is interesting to see that the big 16g sacrifices efficiency (maximum 71%) for higher maximum pressure ratios compared to the evo 1 and 2 small 16g (74%).

The big 16g (16g6) has an absolute maximum pressure ratio of 3.25 (33.1 psi) at an efficiency of 65% and a shaft speed of 145000 rpm. The air mass flow rate of 0.217 kg/s equates to around 280hp. Compressor exit temperature will be around 195 deg. C
Maximum flow rate for the big 16g is 0.27 kg/s (approx. 350hp) at 145000rpm, 60% efficiency and pressure ratio 2.7 (25 psi). The low efficiency produces compressor exit temperature of around 175 deg. C.

For the small 16g (evo 1 and amp;2) max pressure ratio is 2.65 (24.2 psi) with a flow rate of 0.167 kg/s (approx 215 hp) at a shaft speed of 130,000rpm. Maximum flow rate is 0.265 kg/s at 2.15(approx 340 hp) pressure ratio, 130,000 rpm, 60% efficiency.

The standard turbo is sized specifically for Group A/N rally requirements where the 32mm restrictor limits maximum hp to around 300. Careful mapping of the boost curve gives a good flat torque curve – ie. as close to 300 hp as possible right across the rev range. 350 hp is the maximum reliable horsepower achievable with the standard turbo on the evo 3 to 7. Any more and the turbo will be overspeeding and the air exiting the compressor will be over 200 deg. C.

The magnitude of these temperatures should indicate the importance of good charge air cooling.
 
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Discussion Starter · #27 ·
Lightspeed,

do you have the compressor map electronically, if so can you e-mail it to me? Understanding what you have already is the key to making the correct decisions on tuning.

Ta
 
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Discussion Starter · #28 ·
Oli goon - you have mail.

If anyone else wants the maps just ask.

BTW. Engine coolant at 70-80 deg will significantly cool down charge air at 200 deg. But never as good as seperate water system or air to air cooling.
 
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Lightspeed, thanks for all the info. Blimey its enough even to make hh's head spin :)
It's interesting to see that the 16G06 will only produce 0.27 kg/s of air no matter how fast it spins, although the pressure will increase as it spins above 145000 rpm.

When I tried to use the spreadsheet (boost calcs) to see what sort of power this equates to, I ran into a problem. 292 hp corresponds to 394cfm at the turbo inlet or 0.185 m3/s, the spreadsheet equates this to 29.2lb/min of 1.07 kg/s which seems an excessively high air flow. It would also mean that the density of air at turbo inlet (almost atmospheric conditions) is 5.78kg/m3 rather than 1.22 kg/m3. I think that the calculation of the mass flow is incoorrect as using the correct density of air will give a mass flow of 0.226 kg/s for 292 hp.

I also have a spreadsheet for calculating power etc on an engine which i can let you have if you are interested. The problem I have had with this is that there are 2 fiddle factors: thermal efficeincy and volumetric efficeincy. I was using a thermal eff of 41% which i got from Perry (chemical eng handbook) but i think that this is a bit high as it requires a volumetric eff of ~65% to generate the known power of an engine. Do you have good figures for air mass flowrate to power conversions?

The other spreadsheet is a suberb spec of the different models.
 
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Discussion Starter · #32 ·
Oli goon,

Had me scared there - 29.2lbs/min is not 1.07kg/s - you have multiplied your lbs/kg conversion not divided. 29.2/(60*2.2046 )|EQU| 0.22075kg/s.

Keep checking - I'm sorry it's a bit messy - took me a while to get the equations working.

If you can fill in any blanks of the specs spreadsheet i'd much appreciate it.

LOL.
 
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Lightspeed,
.....cooler/.....cooler thing , chill dude , only trying 2 b a bit educational

Intake air temp,
The colder the better , fuel atomisation is not generally a problem with turbocharged engines , the turbulent boost air does a good job if the injectors r in the right place.
Cool charge was the holy grail for turbo F1 cars , they even refridgerated the fuel , to get more into the tanks and help cool the inlet charge when it vapourised from a lower than ambient temp.
 
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Discussion Starter · #36 ·
Evoboy,
Honda experimented and found best atomisation for toluene based F1 fuel at around 45 deg. C. This gave them vastly improved fuel economy for the same power output. They even used thermostatically controlled fuel heater and charge air coolers to achieve this.
 
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Discussion Starter · #37 ·
Lightspeed,

You're quite right - makes me realise why I have given up being an engineer!!!!

Thanks again for all the info.
 
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Discussion Starter · #38 ·
Have you guys heard of fuel coolers? We use one quite sucessfully on our race car. It basically runs the fuel through a small cooler (we used a oil cooler) which is submerged into a container of ice/water mix. This made a noticable difference to the car as we had to lean off the mixture in the programme to prevent overfuelling. The advantage of this is because power comes from the expansion of the fuel air mixture by heating it, (not actually an explosion as some people think- that is detonation!) , the colder the fuel and air is to start with, the more power you get. Although our race car isn't a mitsubishi the principle is the same on anything with a turbo. Think about this the fuel is constantly being pumped into the engine bay and the back into the tank. Thats gotta heat up the fuel after a while!
 
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Discussion Starter · #39 ·
Cooler fuel will indeed make the intake charge cooler and therefore more dense. However the effect would not be large due to relatively large air mass flowrate compared to the fuel mass flowrate. Rough calculations show that a 10'C reduction in fuel temperature would give a 1'C decrease in intake temp which is worth about 1hp.

The fuel tank will also provide a large thermal mass (unless it is empty) and will loose heat from its lower surface in particular. It might be worth considering some sort of air/air or even air/water fuel chiller but the effect will be marginal.
 
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Discussion Starter · #40 ·
Very interesting thread ,Light speed certainly knows turbo's.
putting things basically .the standard turbo can take 2 bar pressure no problem so no real need to change it the turbo if keeping the Hp below a safe figure of 335Hp .350 hp being the maximum the turbo will accept before being unreliable.
Keeping the temperature for air intake and fuel decreases the detonation.better cooling and air flow .
Now can some one advise on how far the pistons and rods can be taken as this would save an awfull lot of money if all would be safe to 335HP.where I would like to take my car when ready .
Despite all the mas air flow figures and stuff .Have I understood correctly .
As its taken a year for some one to actually say that technically the turbo is shafted at above 350HP .
 
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