Discussion
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Tell us and show us more...funny you should ask about hot air be impeded. My next project is to build an exit behind the A.C. heat exchanger and seal it to the top surface of the clam shell. thereby allowing an unobstructed path through the scoop the exchanger and out the top. One of the things that I learned with my Renault R5 Turbo by listening to the Air Research guys who built the turbo is, the exit behind any exchangers intercoolers radiators, they all do the same thing, is that exit flow is as important if not more so than entrance. when standing in traffic our cars A.C. is trying to move air into a high pressure hot environment with a very restricted path out the back. lee 
ROWDYRENAULT said:
funny you should ask about hot air be impeded. My next project is to build an exit behind the A.C. heat exchanger and seal it to the top surface of the clam shell. thereby allowing an unobstructed path through the scoop the exchanger and out the top. One of the things that I learned with my Renault R5 Turbo by listening to the Air Research guys who built the turbo is, the exit behind any exchangers intercoolers radiators, they all do the same thing, is that exit flow is as important if not more so than entrance. when standing in traffic our cars A.C. is trying to move air into a high pressure hot environment with a very restricted path out the back. lee
Interesting - surely then you will not be feeding any air into the engine bay from that side then? Unless you have plans to duct air from elsewhere?Guys I go back to the same thought that I have expressed before. Why does everybody worry about airflow through the engine bay on a Ultima more than other cars with similar horsepower? Compared to comparable horsepower level front engined or midengined cars the Ultima's engine bay is huge. Look at a corvette or a M5 BMW the engine is covered with carbon the hood is insulated to the 9s to keep noise down the hot air off of the radiator on the M5 discharges directly into the engine bay. the M5 has two turbos setting in there somewhere under all that mess in the engine compartment. The bottom of both cars have sheetmetal or plastic covers for aero on at least 1/2 of the engine bay below the motor. Oh yea the M5 has at least a 2 inch by 6 inch vent on the side of the front fender same for the Corvette.
The ultima has a dedicated Airscoop on top, 6 air vents on top of the clam that are 2inchs by 6 inchs, two huge vents on the side of the engine bay, the floor of the bay is open on most cars and there's a huge vent in the back and more vents next to the center vent. I am listening guys tell me again why you think this engine bay runs hotter than the examples above? Oh yea, if you are really concerned ceramic coat the headers for a further reduction in heat into the bay which to the best of my knowledge neither the vette or the M5 are so coated. Lee
The ultima has a dedicated Airscoop on top, 6 air vents on top of the clam that are 2inchs by 6 inchs, two huge vents on the side of the engine bay, the floor of the bay is open on most cars and there's a huge vent in the back and more vents next to the center vent. I am listening guys tell me again why you think this engine bay runs hotter than the examples above? Oh yea, if you are really concerned ceramic coat the headers for a further reduction in heat into the bay which to the best of my knowledge neither the vette or the M5 are so coated. Lee
I'd say the biggest difference of an Ultima with something like an M5 is those engines are front mounted. They're force fed air into the engine bay through the radiator / grill. The Ultima engine bay has no positive air pressure scoop standard. The top scoop is my air intake.
On the road, you won't really notice the "hot engine bay", but I went to a track day 25c and the engine bay was COOKING. I cooked my CV boots (need to be replaced) and everything in general was HOT. And that was only 5-7 lap sessions. I installed scoops now and I am going to remove my cats next time and probably install straight pipes (to remove the mufflers). My exhaust is already ceramic coated.
On the road, you won't really notice the "hot engine bay", but I went to a track day 25c and the engine bay was COOKING. I cooked my CV boots (need to be replaced) and everything in general was HOT. And that was only 5-7 lap sessions. I installed scoops now and I am going to remove my cats next time and probably install straight pipes (to remove the mufflers). My exhaust is already ceramic coated.
Alex I don't mean to be confrontational but you answered your own question. Catalytic converters and racing, not such a good mix. Several Renault R5 turbo owners found this to be true when the heat off of the cats melted all the plastic in the ball joints on the shift linkage. I know it gets way hot in Australia but it gets fairly warm in So. Cal. About 2 months ago my A.C. compressor had to be changed out. It was a Ultima supplied part that had been in service for 6 years. As part of the process I replaced the serpentine belts on the engine. 6 years many days spent in truly hot temperatures +90F the belts that came off where in really good shape. No cracking or discoloration that would point towards an overly hot environment. I just think the whole issue of engine bay heat and for that matter fuel system problems is just overdone. I'm still waiting for my first fuel system issue in the 6 years that the car has been on the road. Oh well, its August the car will see some 110F temps maybe the problem will finely occur. with all due respect I know the problems that different folks have had with their fuel systems are real. I only keep harping on this because I think the mind set here that if one pump is good 3 are better and split tanks with more valves and lines and swirl pots will answer the problem all because the engine bay is to hot is crap. The fuel system problems are related to the poorest design feature on the car in my opinion and that's the stock split tank fuel system. And I see the answer going forward as an intank pump and filters. lee
ROWDYRENAULT said:
Alex I don't mean to be confrontational but you answered your own question. Catalytic converters and racing, not such a good mix. Several Renault R5 turbo owners found this to be true when the heat off of the cats melted all the plastic in the ball joints on the shift linkage. I know it gets way hot in Australia but it gets fairly warm in So. Cal. About 2 months ago my A.C. compressor had to be changed out. It was a Ultima supplied part that had been in service for 6 years. As part of the process I replaced the serpentine belts on the engine. 6 years many days spent in truly hot temperatures +90F the belts that came off where in really good shape. No cracking or discoloration that would point towards an overly hot environment. I just think the whole issue of engine bay heat and for that matter fuel system problems is just overdone. I'm still waiting for my first fuel system issue in the 6 years that the car has been on the road. Oh well, its August the car will see some 110F temps maybe the problem will finely occur. with all due respect I know the problems that different folks have had with their fuel systems are real. I only keep harping on this because I think the mind set here that if one pump is good 3 are better and split tanks with more valves and lines and swirl pots will answer the problem all because the engine bay is to hot is crap. The fuel system problems are related to the poorest design feature on the car in my opinion and that's the stock split tank fuel system. And I see the answer going forward as an intank pump and filters. lee
I think Alex is right - there is a lot less airflow through the bay as the engine is mounted in the rear. Here in the UK cats are mandatory when racing - so that isn't an option either...Gassing Station | Ultima | Top of Page | What's New | My Stuff