Model: 550 Maranello
Engine Size: 5.5L
Refrigerant Type: R134
Ambient Temp: 105
Country of Origin: United States
Hello everyone, just joined today and am hoping to learn more about automotive AC systems and get mine working better.
The car is a Ferrari 550 Maranello, and it's equipped with a Harrison/Diavia AC system based around a V5 compressor and what looks like a parallel flow condenser with a 21"W x 13"H core, rated 4.5kW. I don't know how large the evaporator is, but it's supposedly rated at 3.8kW.
The system cools "OK" when ambient is between 80 and 85, but when it goes higher, and the car is sitting in traffic, it just can't keep up.
Being a hotrodder, I'd like to improve the system, and I understand one way to do this is to increase the size of the condenser, and possibly the compressor? So I'm investigating getting a larger condenser, and I'd like to know if the V5 compressor could be upgraded to a V7?
Thanks in advance for your advice!
If the high side pressure is skyrocketing in traffic, adding a higher capacity compressor will not help, but a condenser with more air flow would. Another consideration is the engine to compressor drive ratio. With a high winding engine like you have, may have slowed it down so it wouldn't blow at the high end.
Of course there is my solution, get the hell out of there being raised in the Chicago and Milwaukee area. Wife wanted to visit her daughter that moved to downtown Milwaukee on the north side. Homes were beautiful, but jammed together, practically all cars were parked out in the street being sprayed with road salt, Better homes had a single seven foot wide driveway, none had a garage.
Stopped in a restaurant to get snack, had to wait 30 minutes to get a seat, and the bill was twice as high as getting a seven course meal up here. Then some mall shopping with ten people in line, then all those damned traffic lights on every street corner. Not even safe for a woman to walk at night. Are you sure you want to move down here? Stepdaughter finally admitted getting worn out just driving to and from work, not very far, but taking up 3 hours of her day. I spent as much as six hours on the Edens Expressway breathing all those exhaust fumes. Moving out of there 40 years ago could be the reason why I am still kicking.
I can garage three vehicles in my home, have room in my driveway to park at least a dozen more off the street. But even this place is getting too damned crowded, at first lived a block away from a 55 mph road, now its a mile. Had three traffic lights in town, now over 50! They call this progress?
Like Nick said, you need pressure readings to tell what is going on. More compressor won't help if the limit is the condenser (and it usually is). Also like Nick said, check the pulley ratios, you want the compressor turning as fast as possible consistent with having it reach its redline rpm the same time as the engine does.
Thanks for the replies and information. Sorry, but I don't have any pressure info, as the car is in my shop at the moment and I'm getting ready to do cam belts and a number of other things (like hotrodding the A/C system in preparation for the Houston summer )
Speedwise, the compressor is being driven just a bit faster than the crank - the crank dampner has a 4 3/4" pulley, and the compressor has a 4 5/8" compressor pulley (6 rib serp belt drive). Redline on the car is 7600 RPM, so the compressor might see 7800 RPM before the rev limiter kicks in. Have read that these compressors are good for 8000 RPM, or can they go a bit more? Also, FWIW, it has a 4 3/4" clutch.
So what about the V5 vs the V7? Is the V7 actually a better compressor, and did it actually sort out some of the issues of the earlier V5?
On the condenser, I'd like to get a new one for an existing OEM application, and take advantage of it being a "standard" and available item in the future, or if that's not an option, have a custom one built. Any recommendations for custom builders? Would also like to have a small tranny cooler built in, which I'll be using as a power steering cooler. Connections for the A/C would exit toward the passenger side (engine left bank), P/S connections would exit to the driver's side (engine right bank) Dimensions would be around 19" high x 30 to 31" wide. Any advantage to having the drier as an integral part of the condenser?
For new hoses and fittings, are Gates PolarSeal recommended? They seem to have higher working pressures, smaller OD's and smaller turning radii than others, and all of these characteristics are very advantageous for my application.
Last question, and it's a typical dumb newbie question - I've figured out that my compressor has a -10 AN thread on the suction, and a -8 AN on the discharge, but the condenser outlet and drier inlet are a strange thread that is smaller than a -8, but bigger than a -6. It's similar to a 3/8" BSPP, and in fact a 3/8" BSPP will thread onto it just fine, albeit just a tad loose. What is this thread called?
V-5's in much larger interior vehicles in like my 04 Cavalier or 2012 Cruze are doing very good jobs. 88 Supra that is really jammed up front, intercooler, engine oil, and transmission coolers is doing okay with R-12.
In these high performance vehicles, more concerned with aerodynamics, sure that Ferrari with R-134a, did the best they can. Only reference we can go buy, is how did the system perform when new? Can accumulate a lot of debris in these systems over the years, air conditioning, also needs air to work.
In terms of reengineering, do you think you can do better than Ferrari?
Even living up north with a strong SW wind, we hit over a 100 with very humid air. Had to make trips to Chicago and St. Paul in that kind of weather. Just left the Supra at home, an all black car, and took the Cruze. Was plenty cool.
Tim can make your hoses if you want to attempt to modify.
Edited: Mon February 11, 2013 at 9:19 AM by NickD
5's have five cylinders, 7's have seven, higher capacity for larger vehicles like SUV's. Both are of he variable displacement type, takes us back to the 60's where the compressors ran continuously rather than that cycling crap that followed it. Load on the engine depends on cooling demand. Say at 70*F ambients, vent temps are quite low, but really kick out like crazy when the temps break a hundred. That is when you get ice cold air.
Would think the V-5 should have adequate capacity for your vehicle. In conversions from R-12 to R-134a with the greater specific heat of R-134a, replacing the condenser was key. I don't even know if you have a tube and fin type or a parallel flow, the latter is what you need, and the more area the better. Assume you have a belt driven fan, if it has a fan clutch, those can really kill good air flow, plus the duct work to get all that air flow through the condenser and not around it. Key is trying to hole your high side pressures in the 220 psi range, at 90*F, engine at 2,000 rpm, AC on, blower at maximum, and the doors open. Give you some numbers to shoot at.
Guess I know what you are saying, associates that just had to have a BMW, was baked alive in those things when in Las Vegas. With a half a dozen kids to send through college, drove a poor man's BMW, a Nissan Maxima, least I had ice cold air.
Ha, had a neighbor with two BMW's, when he met anybody, would say, I own two BMW's. What are people suppose to do, bend over and kiss his butt?
The system has a pair of 16" SPAL electric fans, and the condenser is a parallel flow type. As you say, the V5 is probably "adequate" under most conditions, but I'd like to be able to hang meat inside the car when I'm stuck in traffic on a 105 degree day Probably isn't going to happen, but that's my goal. Ferrari has used this V5 in all their applications, from the smaller V8 midengine cars up to the biggest V12 cars like mine. The problem with my car isn't that the interior space is so much larger than the V8's (although it is a good bit bigger), it's the heat coming back from the engine, and coming in through all the glass that is the challenge. Of course I can have the windows tinted, and try to improve the insulation on the firewall, but would like to see what can be done with boosting the capacity of the system too. I sprung for a rebuildable V7 off eBay about a week ago, and when it arrives I'll post some pics of it & my V5, the condenser, etc.
You purchased a V-7 from ebay? Good luck with that.
V-5s are just fine- the V-7 is really no better than the V-5.-- excepting that V-5s can endure the low charge failure mode a lot better than the V-7s. I see a lot more failures on V-7 when run with low charge, than V-5s. V-5s will tend to leak around the case halfs after about 10 years exposure- that is their primary failure mode now- any V-5 built after 2002 will have the double lip over molded shaft seals design- which fixed the old number one failure mode - the leaking shaft seal.
Other than leaks- the two compressors work about the same and can be interchangeable- as in the old S-10 4 cyl application..
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Something I don't know, is the V-7 a direct fit?
Nick, yes the eBay purchase was just to get a cheap ($50) core to compare its external dimensions, hose connections, etc. to my V5.
If it'll work, I may use it in the future to avoid a core charge if I decide to go forward with a rebuilt V7 in lieu of the V5. Any recommended rebuilders?
GM Tech, thanks for your input - that's the kind of plus/minus comparison I was looking for.
I assume you did not own this vehicle since new, GM Tech did point out that seal problem in your year, and no telling how much your system was played with over the years or how much oil was added or how much sludge you have.
Could just need a good cleaning, both inside and out.
Nick, that's correct. I purchased the car three years ago and the the compressor was leaking at the front seal then. Had it rebuilt, had the condenser cleaned, system flushed, replaced a leaking Schrader valve, and it's been "OK" since, but nothing to brag about.
We were free from the EPA until about 1992 until they took charge, until about that time, GM had an excellent ceramic seal and converted over to that neoprene stupid single lip seal. Took them quiet awhile to put a second lip in there. Also dumped those excellent Scharder valves, have tool to change those without recovering the system, only had to replace that 50 cent core.
Then along comes these stupid quick couplers with a large disk that never resets properly, all in the name of preventing leakage? Never had these problems before the EPA took over.
Then I fell off my chair when the EPA gave DuPont permission to manufacture trichloroethane for the production of R-134a. They banned that around 1977, didn't write that down as a health hazard. We were forced to switch over to acids, that is when our health hazards really drastically increased. Took millions to correct that, as well as using solvent free paints. The technology just didn't exist back then.
Then with R-134a was not miscible with mineral oil had to switch over to a women's facial cream, moisture was a newly created problem, SAE had to nearly double the moisture standards to comply with this law. That idiot Gore started all this claiming CFC's were poking holes in the ozone layer. Maybe, maybe not, but less that 2% of the total CFC production was used in MVAC applications. And that was the field that was hit the hardest.
Then with R-134a, EPA approved of all these crazy alternative refrigerants, so had to purchase a refrigerant identification instrument, more problems. EPA stayed far away from the OE's, but really started picking on techs, at the very bottom of the barrel.
They should get a Nobel prize for causing major problems in the MVAC field. Course now they are saying R-134a is causing global warming so soon to be banned.
We learned how to change that single lipped seal on the vehicle without removing the compressor. There is not a shop that I know of that can be rebuild a compressor, a very secretive and control market. Replacing a seal is not rebuilding a compressor. If moisture did get into your system, generates an acid that is eating its way inside out. Plus moisture mixed in with that women's facial cream develops a sludge that cannot be vacuumed out.
In essence, AC components have become even more throwaway components. Feel its easier and cheaper just to pitch the compressor and condenser, what ever hose are salvageable, and flush out the evaporator with a good leak down test, those are a bitch to replace. Typically, this can be done for under 600 bucks with all new stuff and may be the way for you to go. Talk to Tim on this.
I think GM Tech was talking about reliabilty being no different (actually quite good, for a GM part) between the two. The V-7 does have larger displacement. Case leaks are mostly caused by environmental corrosion creeping in from the outside, which is more of an issue for daily drivers.
Same old problem with buying a used vehicle, can only be lied to about it's history. Even after an inspection, know I am going to have to add another one or two thousand bucks to it in just parts cost along. When my stepdaughter's ZX2 died, searched all over in a 300 mile radius for a used vehicle. With that clunker program, could only find crap. Even new car dealers are selling stuff now, as is, without a vehicle safety inspection. It was cheaper to buy a new one.
We had the EPA and IRS in mind when voting for less government, the FTC was the first to go. With AC with all this crap on the market that shouldn't be there in the first place, you have no idea what you have. So you take it all apart, clean it, get rid of that crap, test what is good, replace what is defective, draw a deep vacuum, inject PAG, charge it properly, then you learn how it worked when new.
If still unsatisfied, that is when you start with the modifications. But not until you have reached that point.
Unless you have a better way to deal with this, if you do, let me know.
The V7 core arrived, and although according to the specs I've read about it, it's supposed to have the same external dimensions as the V5, I can see that certain critical dimensions such as the offset from the mounting bosses to the front pulley is different, because the thickness of the mounting bosses is different.
Also, the V7 does not have a rear set of bosses like the V5 does, which I was hoping would not matter that much, however in comparing the way Ferrari have made their mounting brackets, it does matter, and I really do need those bosses.
While I could probably work around the difference in thickness of the front bosses, the lack of the rear mounting bosses is a showstopper. I wonder if a rear cover (with the mounting bosses) from a V5 could fit on a V7, or if it's simply time to abandon this upgrade idea?
Poor compressor performance can generally be told by pressures, typical is low differential pressures. To get good advice should post those, both at idle and at 2000 rpm specifying the ambient temperature and humidity. AC on, doors open, blower at max.
Common problem with the V-5 or V-6 is a sticking control valve. Also has an interference fit clutch disc that can work loose, plus other electrical problems. Many that came here over the years, assumed their free-on was low and end up blowing up their systems. Just saying, we should learn what the problem is before making changes.
Before I get in to the "hot rodding" part of this, let's look at the two types of V7 compressor mounts that are common.
Pad Mount. bolts go through the case at 90 degrees to the shaft axis:
Pad mount V7 for Corvette
Ear Mount. Bolts go through ears on case parallel to the shaft axis:
Ear mount V7 for S10
Your need for a "rear mount" sounds like a V5 ear mount that used a tapped hole in the back end for a strut on the 4 cylinder GM econoboxes like Cavalier. Pics of your mounting issues might help.
Before you can improve system performance, you need baseline data. A larger compressor displacement can help at low speeds, but you need enough condensor to keep up. A thermocouple on the condensor discharge will tell you what you need to know. Many other factors like radiated heat from the powertrain, evaporator capacity, cabin airflow etc also affect the system capacity.
Here are the performance graphs for the the V5 & V7:
Note that either unit has the capacity to overrun your evaporator without running to full speed. The V7 will get there at a lower rpm.
Here in Las Vegas we do a lot of things to improve low speed performance at high ambient temps. Limo passengers do not like to sweat. You can get more out of an evaporator by running it at lower temps, increasing airflow - or both. Insulating suction lines, keeping powertrain heat out of the cabin, etc. are always good. Lots of things you can do.
Condensor performance is at the top of the list. Get some performance data idling, and back it up with a full load test. Doors open, cabin fan on highest speed. Engine RPM 2500 for 5 minutes. Record pressures & vent temperature / condensor discharge temperature while the engine is still @ 2500 rpm.
With that data we can make some accurate recommendations about what to change next.
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Bohica, thanks for the performance curves; here's a pic showing the V5 and its mounting on the left, and the V7 on the right
Closeup of the V5. As you can see, the Ferrari casting utilises a quasi-through bolt arrangement between front & rear covers, so I really should try to keep this mounting arrangement the same, else it'll probably overstress the Ferrari casting.
Edited: Sun February 24, 2013 at 8:55 PM by cribbj
Well, you could probably find a way to make the V7 work - but the performance curves should tell you that the V5 is already de-stroking by 2000 rpm with your condensor. Given the complexity of the mounting changes, i would stay with the V5 & look to improve the rest of the system.
V5 / V7 compressors came with several different control valves. We try to keep the lowest set point valve in that compressor here in the desert. The "Z" valve, color code Green is a 37.5 psi valve. This means vent temps in the low 40's at best. Never had an icing issue with this valve. Other valves are rated with higher pressures. Orange valves are common.
Insulating the suction line can make a measurable difference. I have had a couple of 900 Turbo cars that proved that very well. Adding insulation that has a good IR rejection to the low side lines keeps the engine bay heat load off of the condensor. Insulating the passenger compartment obviously helps too. I have always used a foil faced fiberglass cloth insulation for engine bay hoses & surfaces. McMaster-Carr sells it as P/N 88475K2 and I secure it with P/N 1601T61 straps. That insulation got us to the moon & back.
Increasing airflow over the condensor is always good. Increasing airflow over the evaporator can help, but some people can't stand the added noise.
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Thanks Bohica, this is the sort of insight I was looking for. I'll plan to do the following:
1. Abandon the idea of upgrading to the V7
2. Try to source a larger condenser, with integrated transmission cooler, which I can sandwich onto the radiator/oil cooler setup so that I have a stacked assembly that is two cores deep. My existing setup is one core (radiator) deep in some places, and three cores (radiator, condenser, P/S cooler) deep in others. I'm sure this isn't helping the heat transfer and airflow distribution.
3. Install more/better insulation on the compressor suction line, and look into that Z or green control valve you mentioned. I would assume since our environment is much more humid than yours, that icing might be more of an issue, so I'll lookout for that.
Suggestions where to source condenser cores? I've already contacted AC Kits, but they advised they don't have what I'm looking for. Have also tried Vintage and Classic and been brushed off by both.
Generically it would be a parallel flow condenser, with integrated transmission oil cooler, and overall dimensions of 29 to 32 inches wide by 18 to 19 inches tall. I'd like the condenser connections to exit the passenger (right) side of car, and the transmission oil cooler connections to exit the driver (left) side.
Here is a short review of your car:
Pros: Attracts chicks even better looking than itself.
Cons: You cant stuff all of them in.
About all I could find checking on replacement parts for this car, did find replacement hood lifts, had to replace those recently on my 88 Supra Turbo to save my head from getting banged. Also saw the new sticker price on this car, over $200K. Not a single comment about AC performance. When I run into stuff like this, try to contact the factory for information.
In regards to modifications, always the last step in my book, would pull the entire system out and check everything out first, clean it up, and do leak tests. Even the most basic things were not done on this vehicle, like posting pressures.
If I even dare compare your car to mine, not only a conventional radiator and condenser, but adds an AT, PS, engine oil, and an intercooler as well, really as a ton of stuff in there. All black, worse possible color for a car like this, but yet the AC system works incredibly well. But certainly requires maintenance to keep it that way, we live in a filthy world. Heck, just to change the timing belt on this thing, had to clean out my 2 1/2 garage so I had a spot to lie down all the parts I had to remove. Surprised the even all fit back in that small compartment. Other stall and a half was loaded.
My guess if you need anything, would have to go back to my home country to get it. Can you speak Italian?
If you want to try a car with a V-5 that will freeze your butt off, even in a 125*F ambient, try a 2004 Cavalier sports coupe. Mine even as the about the same color as yours.
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