Intercooler specs please?
 

Could anyone post any information on their intercooler setups? Performance specs, POH adendums, Pictures?

I've seen the Intercooler .bmp in previous posts. I'm really curious between the AA and Riley cooler setups. Some pictures would be great. Please?

I would be very appreciative. Thanks.

Richard

American Aviation Intercoolers
 

Richard,

American Aviation's intercoolers are no longer available but they still service the product and have spare parts available, such as the induction boot, etc. The units are built pretty tough, and all you're dealing with is a heat exchanger, much like the way an oild cooler is constructed, only instead of oil moving through it, it's hot air. About your only choice at this point is to buy a bird with the units already installed, or contact Riley/Tule Aero for a new install. I'd be interested in knowing what today's 'ticket price' is for admission. I'll bet it's sky high.

As far as specs, max placarded power setting for ISA at sea-level for takeoff is 35.3" hg. The engine produces basically the same horsepower, but it does so more efficiently and with lower power settings, since the heated induction air from the impeller (Turbo Discharge Temperature) is reduced from about 220 degrees F down to about 80 degrees.

Without intercoolers, the compressed induction air can get as hot as 300 degrees F even though the outside air temperature may be at or below zero. Since hot air is less dense and contains fewer oxygen molecules than cold air -- as much as 40% less -- much of the power that could be produced by the turbocharger is lost.

The intercoolers are a great benefit during hotter than normal conditions and at high density altitude airports. Other advantages include better engine detonation protection, improved climb rates and higher cruising speeds.

Typical power settings, fuel flow in PPH, TAS (Knots) and Servo Inlet Temp:

10,000 @ 75% = 33" Hg @ 2400 RPM, 88 PPH, 195 Kts & 57 F
10,000 @ 65% = 30" Hg @ 2400 RPM, 76 PPH, 184 Kts & 52 F
10,000 @ 55% = 27" Hg @ 2300 RPM, 64 PPH, 170 Kts & 46 F

16,000 @ 75% = 33" Hg @ 2400 RPM, 88 PPH, 210 Kts & 65 F
16,000 @ 65% = 30" Hg @ 2400 RPM, 76 PPH, 198 Kts & 56 F
16,000 @ 55% = 26" Hg @ 2400 RPM, 64 PPH, 182 Kts & 48 F

The above figures are 'Best Power' Fuel Flow settings, but by using the 'Best Economy' Fuel Flow for 65% and 55% power, you can shave the fuel flow down to 67 PPH and 57 PPH respectively (running at or near peak EGT).

It would almost be cost prohibitive to add intercoolers because of Mr. Alan GreenSPAM's thing called 'inflation'... as I recall, the American Aviation intercoolers were installed on our bird back in '86 and at that time the total price was around $10K, including the paint. Best to look for a bird with these units already installed.

SkyKing

Whoops.. I forgot to mention that the above information pertains to the P337.

SkyKing

Thanks for the info, and yes they are really, really expensive. I found some used ones for 9k. That's about as good as it gets. Riley is the only other game in town and they want 14K.

Max Takeoff MP with AA intercoolers
 

Happy Thanksgiving; I have a question that's been bothering me. I own a 79 P337H with American Aviation Intercoolers installed in the late 1980s. My question is; all of the POH supplements they provided me show operating limitations and placards of Normal Take-off power-32.8 Hg MAP (Standard Sea Level Conditions). Yet my actual aircraft Placard says 35.3 Hg MAP. The 35.3 agrees with my research across this forum; but why the difference between what my supplement says and the actual aircraft Placard. Bottomline question; What should I be using?? In my aircraft, if I apply full power at sea level, I can easily exceed both max RPM (2800) and even MAP of 35.3. Why the difference with the supplement directed placard label and the actual one in the aircraft?

121 EW P337H owned since Aug 2018

I have a 1974 P337 with air conditioning, Horton STOL, no wing de-ice boots, and the Riley intercoolers. I mention all these things because each impacts performance, though none of the mods actually say how much they impact performance!

I used to use 33"/2500RPM at 17,500 and obtain about 202kts on 34GPH (204pph). Lately, I've been at 31"/2500RPM at 17,500 and obtain 196kts on 26.6gph (160pph). Note that this is "slower than book", but "book" doesn't account for the STOL kit or the air conditioning scoops (or the intercooler scoop/venturi).

My POH calls the 33"/2500 "75% power", but calls for 80pph per engine (13.3gph), which I cannot obtain without overheating the engine.

The Riley STC instructs to reduce MP by an amount between 0" and 2" depending on altitude, and it's essentially a straight line with 0" at sea level and 2" at FL200.

So my theory is that if I run 33"/2500 at 17,500', I'm at more like 85% power, based on fuel stoichiometry. Reducing MP down to 31" brings fuel usage back in line with book, implying a return to 75% power. And of course, temperatures are much easier to control.

QUESTION: Nothing about the intercooler installation should increase the rated power output of the engine, should it? Sure, the engine will produce more power if I let it, but presumably the main everyday benefit of the intercooler is better thermal control (if MP is reduced to account for the colder/denser air bring introduced into the engine). A secondary benefit is that in emergencies, slightly more power than stock, is available. Does this sound like a good way to think about aftermarket intercoolers?

BTW, my rear engine actually runs cooler than my front engine. But during climb out on hot summer days (33"/2500rpm/140mph/cowl-flaps-open/full rich), I still have to watch the temperatures on both engines.


Thanks -- Dan

Max Takeoff MP with AA intercoolers
 

Still wondering about Takeoff max MAP with AA intercoolers, is it 35.3 or 32.8?

A wild guess on my part: perhaps output level at a cooler 32.8 Hg is similar to output on a hotter 35.3. Not that you aren't entitled by the gods to any extra power, but for the FAA, STC's seem to be based on keeping risk factors and tolerances at or lower than factory spec. You get improved efficiency, engine life, etc., from the cooler temps, but leveraging them to get HP above the factory spec was perhaps considered unapprovable, or more difficult to certify, and thus the placard.

Again, just a guess. But then again, maybe Dan was hinting at the same thing, on second read.

Yes, that's the conclusion I came to, albeit with very slightly different numbers since mine is Riley and weebyf15's is American Aviation.

Dan

You should not be exceeding these values, your limits are not set correctly.

Thank you all; Herb I have not intentionally exceeded the limits and will talk to my Mechanic to get them adjusted. I mostly fly turbine aircraft, in which the throttles are full up (military power) for takeoff. As Of late I have noticed this results in too much pressure about 36 and rpm about 2900. So back to the original question in this thread from me. The placard and Pilot Sup both say AA inter coolers but the sup says 32.8 and the placard says 35.3, which should he adjust it to, or more importantly, which should I ensure I do not exceed.
Thanks if you can help

Call them
 

Great tip; got an immediate answer and they sent me the correct POH supplement. A/C placard stating 35.3 MAP was the correct answer. Thank you

Riley STC
 

Who holds the STC now?

American Aviation still has the STC. This is a different system than the Riley Intercoolers