i bypassed the throttle body heater thing that is integrated into the cooling system on the 2005 prius, my tests,not exactly scientific but here are the results before bypassing the coolant through throttle body : 93 degrees down here in south florida, between 130-140 degrees intake air temperature in traffic, and this is where i notice major power loss, cruising the temperature hovers between 125 and 130. my gas mileage has been consistently 45 mpg over the past 2 weeks of 90-93 degree weather. bypassing the coolant though throttle body: 93 degrees today and IAT was between 95-110 consistently, during stop and go traffic i was between 105-111 degrees, cruising it hovered between 95 -100. gas mileage improved about 3-4 mpg to 48 mpg, power has been improved especially low range torque. im going to do this modification on my 2001 prius and report results
I wonder why your IATs were so high previously. Today I was watching my IATs both sitting at stop lights and cruising between 40mph and 55mph. With a 98deg ambient temp the IAT never got over 105deg F. This morning the ambient temp was 62deg and the IAT cruising was 68deg.
I've seen 120F+ IAT. I'm guessing a bit, but it seems that prolonged heat soak in the sun, followed by driving that does not include a substantial amount of cruising at appreciable speed can give me multiple minutes of signficantly elevated IAT. It quite visibly declines during any periods of even moderately higher-speed (say 40+ mph) cruise. Oh, and this is Albuquerque, where the air temperature has not yet broken 100 this summer, and generally below 95 for these observations. When the same car leaves the shaded garage at an overight ambient of 80F, I don't see IAT break 100. Obviously I'm guessing from not enough data, but it appears that heat retained in some under-hood or body components can be a factor here. I don't have an opinion on mileage or other operating characteristic effects.
That makes sense but the first data I presented for my car was after sitting in the parking lot all day in full sun. My guess is that he is sitting in traffic with a lot of other cars out there so the actual temps are very high due to the heat island effect and all the other energy produced by other vehicles. My LS1-based cars and trucks would see 120deg IATs when sitting in traffic as well but they would drop almost instantly once moving.
it could be due to air in my cooling system? usually my coolant temp hovered around 180-200 degrees, when i sit in the sun, say parked my IAT would be pretty high while the coolant flowed through it
Thats correct. Your numbers are right on. Its all about heat soak. The IAT will cool down when air starts moving under the hood at a good cruising speed. My numbers mimic yours exactly. I now notice better upper end torque with effortless passing speeds. Its hot as hell down here in July. Completely unnecessary to run coolant through the throttle body. At the very least it will prematurely fatigue the throttle motor. But man I got really flamed when I first posted this mod. F@*k 'em. I know it works.
well no offense to the people who dont support this modification, but since i live down in south florida, and i drive in somewhat bad traffic during morning and afternoon this modification makes a difference to me. since it hardly gets cold down here in Fort Myers / Cape Coral this modification will really help me. Yesterday i was cruising along on a 5 mile road, pretty level around 48 mph constantly and i achieved 62.5 mpg, which is pretty high to me.
statultra, Since reading about your results I've been toggling the IAT gauge on my SG2 and I did see a high IAT of 119 for about 1 minute the other day after the car sat in a hot parking lot for 20min. Temps overall seem to be around 6deg F over ambient at all other times though and I don't seem to get any real heatsoak temperature spikes when sitting at long lights or anything. I'm guessing your weather conditions must be different than mine and that your intake air tract is retaining more heat than mine. I'm glad it seems to be helping you so far. Please keep us updated with as much real information as you can. if in the end it doesn't end up truely helping at least you can say you tried and if it does help well then you were one of the pioneers. edthefox5, You were flamed because you were making grand claims that had no quantifiable data to back them up yet you vigorously defended those claims. Having done this mod on numerous other cars and not seeing a benefit (other than being able to remove the TB without leaking fluid everywhere) I rightly called on you to provide information backing those claims up. Just as I have been doing with statultra. This is how you weed out false claims and create rigorous data.
Oops, I think (my own) observations above were on my 2002 Audi A4 1.8T, not the family Prius. I still think there are probably some heat soak and recent history effects on Prius intake air temperature, but I've had the SG2 in the Audi the last couple of weeks, and was using most gauge entries to watch battery stuff during the week I had it in the Prius. Sorry
if you are driving in traffic, heatsoak becomes a major issue with the toyota prius, since the engine shuts off and the water pump cannot pump the antifreeze out of the engine, thus increasing the temperature of the coolant. then when the engine fires up the hot coolant gets routed through the cooling system thus increasing the intake air temperatures, although colder air intake temps will yield a richer mixture ( i think ) it really helps in the summer. the difference in the IAT can be observed after cruising, and driving through traffic where the IAT rarely gets above 110 degrees, versus before where it would range from 120-140 degrees in traffic with an ambient temperature of 93. as some of you know in florida the rainy season is in full swing, and temperatures drop as much as 20 degrees when a storm is above you. during a 75 degree ambient temperature my IAT was between 85-90 degrees. now this isnt a totally scientific experiment, but none the less the intake air temps are vastly lower than it was before the modification was completed. i notice more low end torque in very hot weather.
i could feel the "pulled back into the seat" feeling. its more noticeable than before, in hot weather I would get bogged down in traffic.also, im pretty sure its not psychological.
How about two test runs: 0-60 mph - w/o mod 0-60 mph - w mod If there is more 'umph', the times will tell. Bob Wilson
The battery SOC would cause issues with this test as well as the fact I do not think there is enough of a HP/TQ difference to have much effect in 0-60' times. My times were all over the place when I raced mine on a certified race track. I ran it 14 times I believe.
ill do a 0-60 with modification, whenever i get a chance im going to do it on my 2001 prius, without mod and with it
Is it possible to put a valve to shutoff the water for summer months or when the water goes out of the T/B do it go some where else vita to the rest??
i was going to ask that.. hehe.. a valve. btw, link this to your previous topic. I would like to see pics ( if you included them) hehe
The reason I asked is that the "seat of the pants" feeling is highly subjective, particularly on a throttle by wire car. The Prius in particular is going to siphon off a variable amount of power depending on the battery state of charge.
I noticed the performance advantage specifically when battery levels were just 2 bars. Im going to post some 0-60 times taken by GPS, not sure how accurate it is but we will see.
