Any turbo-charged passenger car sees 140-160°C upstream the intercooler. On truck turbo-charged diesels, 240°C at max power is the norm nowadays.
The whole point of the intercooler is to not send this air to the engine.
What sort of temp would you expect after the intercooler?
Non-intercooled turbo-charged engines are silly.
Excluding the Cirrus fleet, they are however probably the majority of turbo installations…
My thermodynamics is rubbish, 40 years after leaving univ, but Flyingfish’s 37.5 inches of MP is quite a compression. That is way more than turbo-normalising which is probably what most non-intercooled installations are.
I think I remember that an increase in absolute temperature (ie Kelvin, K) is roughly proportional to the increase in absolute pressure. P2/P1 = T2/T1. With a doubling of the pressure, the temperature also doubles (in K).
Wow! It seems like this thread is drawing some attention. Thanks everyone. I’ll try to answer the questions and hope not to forget anyone:
@Peter_Mundy: no it is not a typo. I know it sounds like a lot but it really is leaned at this level.
@dirkdj: Despite having GAMI balanced injectors, I am unable to run LOP in cruise because TIT hits 1680 F which is above the 1650 I have set myself as maximum.
POH value is 1750, but I won’t let my turbo get that hot if at all possible. This is by the way one of the reasons I am doing this work: trying to lower TIT by 30 degrees F during LOP operations. Ideas are welcome. And hint: more fuel flow causes TIT to increase when on the lean side of peak.
@Arne: I did not know that the TOT of automotive engines was so high. Do you know what the values are AFTER the intercooler? I am very keen on comparison numbers. My feeling (sorry no facts – failed probe) is that the cooled air will still be at least at 70 degrees despite OAT at MINUS 23. I am not an engine expert but such high air temperatures make me fell uneasy about the health of the engine and the efficiency of the combustion process. This said I would really appreciate your assistance in providing reference data. I will also look at the procedures link you provided.
@Peter: thank you. I have also other findings which are significant enough to provoke immediate action to fix two known problems of this aircraft: poor heating and a hot spot in the left side of the engine compartment. Simple fixes in the works :-)
Full disclosure: Designing cooling systems is what I do for a living.
LeSving wrote:
I think I remember that an increase in absolute temperature (ie Kelvin, K) is roughly proportional to the increase in absolute pressure. P2/P1 = T2/T1. With a doubling of the pressure, the temperature also doubles (in K).Not quite, unfortunately. In an adiabatic compression, T*P^((1-gamma)/gamma) = constant. Add to this the fact that the compressor is only about 65-75% efficient.
Any turbo-charged passenger car sees 140-160°C upstream the intercooler. On truck turbo-charged diesels, 240°C at max power is the norm nowadays.3 to 30°C above ambient up to 6000ft, in a land-going vehicle. The lower end of the range for a diesel, the upper for a gas engine. Plane intercoolers look very small to me, but cooling air side flow rates are probably I lot larger than I am used to as well.
The whole point of the intercooler is to not send this air to the engine.
What sort of temp would you expect after the intercooler?
37.5 inches of MP is quite a compressionThe MAP reported is always an absolute pressure, STD is 29.92".
Flyingfish,
You may safely operate at the 1650°F TIT and above; you need to be able to lean to peak TIT and beyond till the TIT drops. Since you have GAMIjectors, you are entitled to the tech support at GAMI. You may want to contact John Deakin first with my compliments: [email protected] .
John is retired and has time to answer your questions, he will escalate to George Braly if needed.
The most common problems with Continental engines not running smoothly LOP are: the rubber coupling in the induction tubing and the spark plugs. I would recommend you change to Tempest massive or fine-wire spark plugs; They made all the difference in my otherwise perfect engine.
It would be helpful to do a GAMI test at two different altitudes, say 3000 and 6000, writing down the temperatures of EGT, TIT, CHT for each cylinder and airspeed and fuelflow. Upload to Savvy and send a link to John for examination.
I don’t know where the TIT probe is located in the Extra400, but it is possible that it measures a temperature which is quite a lot lower than on the actual turbo inlet. In the PA46 where you have two turbos and only one TIT probe, located nowhere near the intake of any of the turbos and situated much closer to one than the other, 1600F is considered desirable, certainly not above 1650F except during a short period (e.g. leaning).
@Arne : you got my attention! Can we become best friends? 
(just kidding!)
I believe that the intercooler in my plane is quite bad. It is installed at a 90 degree angle to the incoming air. This air is provided by a NACA inlet which (according to NACA) is a not an optimal way of feeding a radiator. I am very anxious to get the Intercooler Out probe working to see how well it cools but I would be pleasantly surprised if efficiency were beyond 50%.
@dirkdj: when I did my leaning attempts from some point above peak, the TIT increased to above 1700 ( so I swept quickly through this) and then started to drop, THe problem is that by the time TIT is down to 1650, my richest cylinder is maybe 150F LOP and that is not smooth anymore.
I must find a way to drop my TIT from 1680 to 1650 F – this is the point just before the engine runs rough.
I will gladly contact John Deakin and mention you. Thanks
Arne wrote:
Non-intercooled turbo-charged engines are silly.
I don’t have an Intercooler but I believe 500 fpm @FL180 with only 115 hp aren’t silly at all – except for an F16 maybe 
A positive effect of not having an Intercooler is that a carbureted engine is not prone to carburetor icing – I’ve been told. At least I didn’t ever see it in my aircraft.
Flying fish,
You probably need some tweaking on the GAMIjectors. What kind of engine analyser do you have?
dirkdj – I have an EDM930.
While I am not completely happy with my GAMIjectors yet, I doubt that they can be tweaked enough to make the engine run smooth so deep in LOP territory.
Furthermore there is a very narrow LOP band where power loss versus ROP remains acceptable. Any leaner and the power loss becomes excessive. In my case I think it is between 50 and 100 F LOP.
