bjhines

Tony, I will disagree with you on your priorities of importance. Your poorly shrouded examples are going to allow some very hot water to pass to the outlet. Is that really desireable?? I dont think so. I look at OEM design with great respect. I can think of a few modern improvements that have made it into nearly every car on the road. We can use some of them on our cars and fan shrouds are easy and proven to work. Higher coolant temperature(there are a lot of reasons this is GOOD, not just emissions related) Higher coolant pressure(steam bubbles) constant metered bypass into the recovery tank.(air/steam expulsion) optimized coolant volume(smaller engine volume, smaller radiator volume, smaller port and hose volume) optimized coolant flow(hotter cylinders and exhuast passages with cooler intake passages) optimized cooling fan control(I am playing around with this right now) optimized aero effects on radiator airflow(in the front clip, FAN SHROUD, underbody, and engine bay) optimized engine control systems for more consistent thermal demands. There are better things to discuss besides how you can get away with no fan shroud or not.

You guys are crazy... I mean that in a good way. THERE ARE BIGGER FISH TO FRY!!! You both agree that a decent fan and a decent shroud are the way to go. FINI! I designed a circuit to use a 3/8"NPT sender to automatically switch the 3-state(OFF/LOW/HIGH), 3-wire Ford Taurus fan. I have an AC-full-on input, and I have a relay output for a second fan. I have a dozen mosfets in paralell on the bench trying to reliably PWM control this beast(heatsink and heatsink cooling fans are too damn big and expensive though). Through all of this design work I keep wondering just where the best location for the sender is, and what temperature parameters are best. I placed MY sender in the top of the water outlet, but I am not married to that position. I considered placing the sender in the radiator outlet. I decided to have the fan sender very close to my gauge sender. The fan sender is on the cool side of the thermostat while the gauge sender is just below it on the hot side of the thermostat. My settings so far are based on what I have found avaiable from aftetmarket suppliers. Low temp(185F) thermostats will use lower ON-temp settings for electric fans. High temp(195F) thermostats will use higher temp ranges for the fans. Most of the aftermarket controllers have OFF-states that are 15-20 degrees cooler than the ON-state. This temp range is built into the fan "switches" with only 20% accuracy. I developed my circuit to mimick this behavior with much greater accuracy, precision, and adjustability. I can see changing the location of the sender GREATLY changing the requirements for both ON-state and OFF-state settings. My next design will get even better with a Schmitt Trigger/comparator. I used Zener diodes in the first design, but they are prone to wander as ambient temps vary greatly underhood.

I dunno JM.. I see your TOE-OUT thinking here... You are thinking the inside tire is scrabbling to pull the car around the turn. Since it doesn't do much anyway, then why not have it pulling inward in the turn. But Leon has a point you should try to get your head around. The outside tire is working BEST at a fairly high slip angle. The inside tire is working best at a reduced slip angle in the same highly loaded turn. That would indicate slight toe-in. But I agree that there are so many variables that can all affect everything else that it is hard to know why some things are working for most people. If you can get the thing sorted and fast you might end up with some odd settings that work for your car. I built a super stiff chassis, and I sprung it lightly. I am going to see what works this season.

To meet todays standards you would need higher bumpers, and frame connections that would not allow them to fold under. The entire way a new car crumples is built into every piece of sheetmetal. We can't easily model the chassis and wreck it... can we???? You don't want the engine in your lap You don't want the fuel tank splashing you or the entire undeside of the car "" legs pinned legs smashed into column and pedal box ejection roof in your head doors pinned against you I just don't think you can shoehorn modern chassis safety engineering into a 240Z. Making the car stronger also makes it more likely to injure the driver and save the chassis.

It will eventuall end up as a green or black wire. ...

I think there are cheap/small relays that will do the job for these fans. I think that many failures of the Mini-relays are due to improper suppression and arcing across the contacts. I need to design a good surge/spark supression circuit for these 50Amp Mini-relays. I do not think the large 75A relays are a good choice. They do not make a changeover(nc/no) version, they are too expensive, too big, require too much coil current, they do not fit neatly into sockets, and the contacts need boots to insulate the connections. I would prefer to use only 2 relays to do the entire switching job. One 50A single throw for power ON-OFF, and One 25A/50A changeover for low/high speed. Edit... My method is actually dissapating more power(heat) through 2 relays right now(one for ON/OFF, and one for switching HIGH/LOW). I will rewire the relay outputs to allow 2 independent fan relays One High and One Low relay fed by a branching power wire. I am currently testing RC suppression as my best option. Diodes are not working out with the 3 wire motor very well.

Strotter, I am with you there on the additional functions. I included an override input to force high speed operation. I also included an input that switches to ground(800mA)on high speed which could run additional relays, or indicator lights, or other functions. I could add any number of additional features like delays for on/off/functions, etc.

Dan, Which relays are you currently using? This is the next phase of testing for me. I am trying a variety of suppression techniques to see what works best on the scope.

First I want to give a little background... Track cars ~can~ get away with little or no cooling fan power for a variety of reasons. With that said, I have seen many track cars overheat on the grid. I have seen drivers start and stop the engines every time they move up and accidentally kill the battery on the starting grid. I want NONE of that. I admire the BMW drivers that can sit on grid with the AC running, while discussing technique with their instructors(I have a BMW M3 and love it). I have tried a few options for electric fans in my time, on a variety of cars. Most of the aftermarket fans are wimps that would not cool a go-cart on hot/humid summer days in the SE USA. To provide proper cooling power you need something that draws ~30-40 Amps(400-500 Watts). Proper cooling power is easily attainable with DUAL fan motors. Unfortunately, most of the dual fan setups are too big to fit on our small radiators. If you can fit them, then I would definitely use DUAL fans. Dual fan motors are within the amperage ratings of fog-light relays. This means that parts to run them are cheap and replacements are as close as your nearest Walmart. -------------------------------------------------------------------------------------------------------------------------------------------------- Enough on dual motors vs 2 speed motor, I have a Taurus 2-speed fan and I need to control it. This fan motor was available on a variety of Ford cars for over a decade. There are a variety of shrouds and fan sizes that all seem to use the same 2-speed motor design. Ford really loved this fan. The Factory replacement is priced over $400, but Dorman offers an aftermarket replacement for $150. This thing is POWERFUL!!! It uses a little less than 20 AMPs on LOW and nearly 40 AMPs on HIGH. The high speed current draw is well known for melting foglight relays. You can get 50A mini relays but they are pushed to the limit with high ambient temps in the engine compartment. There are 70A mini relays available if you know where to look. I wanted an adjustable, 3-state(OFF/LOW/HIGH), 3-wire(2-speeds w/ground) Ford Taurus fan controller that uses a single sender. I have seen many ways to SWITCH the 2 speed fans and their high amperage requirements, but I have not seen a neat way to control the relays automatically. I have a list of considerations I used in my design; Low cost parts IN-stock parts availability Temperature Sender to fit 1980s GM thermostat housing with 3/8"NPT port and weatherpack electrical connector. Regulated/isolated circuit design fully adjustable temperatures for off, low, and high speed Proper change in temp from on to off state(hysteresis) HARD switching for the main relays to reduce arcing and fouling indicator lights to aid adjustment and confirm operation(ON, LOW, HIGH, OVERRIDE) AC/override control to force high speed ON I designed a circuit that uses an adjustable voltage divider with a single thermistor(sender) to drive a pair of transistors through Zener diodes to control a set of micro relays. The micro-mini relays will ensure that the main fan switching relays are switched solidly no matter what. The circuit is very simple in theory, but getting it to work properly adds complication. The voltage divider uses one sender but has 2 branches to allow 3 states. It was a little tricky getting the ON-OFF states close together without putting too much current through the sender/thermistor. I used Zener diodes to keep the change in states very close together. The other problem is that changing one set point changes the set points for all the states. I was able to minimize that issue with some more parts. I end up with 2 adjustment screws... The low speed screw sets the LOW-ON temperature, The high speed screw sets the difference between the LOW and HIGH ON points. The off state temeratures are built into the circuit design to be ~10 degrees lower than the ON states. This hysteresis is not consistent over the entire adjustment range, but it is within a few degrees over a wide range of temps. The temperature settings I am using now are what I have seen discussed in books and forums. .......LOW....HIGH ..ON..185.....200 OFF..175.....190 The settings are adjustement-repeatable and precise. I use a 240F heater and thermocouple to measure temps. I get no more than a degree of variation in tests. I have run tests with the circuit at 40F degrees and the circuit at 180F degrees. I only get a 3 degree variation. ...

Considering that Gasoline boils faily easily, I would not consider that as a safe alternative. I think Tony's example was for a land speed car that ran for a few minutes at a time. Diesel might be a better choice and most heavy equipment carries hundreds of gallons of diesel fuel to work with.

Tony D. drug out the fuel/oil example a few years back. I don't see that as a good alternative when you only hold 10-15 gals of fuel.

That is not gonna do it. You need the ignition source and toggle switch powering the 86 terminal through the coil and out 85 to ground. Many relays have diodes in parallel with the coil so it is important to make 86 the 12v input and 85 the ground. The BATT source goes to terminal 30. 87a as low speed and 87 as high speed are correct.

Yeaa... Smoking Tires/Farah is NOT a car guy. I mean REALLY, The Fake Ferrari screams moden unibody w/struts. Car guys that REALLY like cars look at the assembly of parts and not just the image in 2 dimensions. I spotted the fake in 2 dimensions, It would have just BLARED OUT FAKE FAKE FAKE Ferrari the moment you opened a door. That Smoking tires dude is just regurgitating the stuff he reads in car magazines, He has no idea what makes a car a car. He is NOT a car guy. He is just a wannabe TV star who could have just as well been talking about Ginzu knives.

Junkyard, Z-barn, and others may have them.

The harness was designed in 1968, to use no more than 45 AMPs. Everything about the original electrical system is inappropriate for modern electrical devices. The external regulators are noisey, unstable, wiring has gone bad, etc. The original alternator is heavy and weak compared to todays versions. The whole idea of an AMMETER as a useful gauge is antique and misleading. Anything you add to the electrical system is going to make the AMMETER less accurate. I outlined my method for fixing these problems in the previous posts. You need to get rid of the AMMETER and re-route your power distribution accordingly. This will isolate the original harness and all of it's weaknesses. If you are hooking things up to the battery posts then you are only creating more problems. The battery+ is the furthest from the alternator in the original power distribution circuit. The battery does not run ANYTHING in your car when the engine is running. The battery is just another drain on the alternator. Anyone who thinks the Battery will somehow buffer power draw is completely wrong. The battery makes the power problems WORSE on the harness and alternator when you hook things up at the BATT +post.

There is a 2-pass design that solves the issues I mentioned. It has much larger tubes for good flow. It also uses the second pass to get rid of heat picked up from the oil cooler. and it's rediculously expensive.

That is very nice work Jon. I really like the old school crinkle paint.

I would not do that! Remove the distributor or you will be sorry.

This is truly a tough problem to deal with. I have given some thoughts to this but nothing has come of it yet. Improved radiator design could use fancy header tanks, mixer tanks, etc for better consistency, but there are bigger fish to fry. Do you really want a $1000 radiator in your car? 1. Coolant flow through the engine could be improved on the Nissan L6 and the Chevy V8. What I notice in modern engines is that they maintain very high temps internally. They also spend some effort to keep intake passages COOL(er) and the cylinders HOT. 2. Outlet designs have changed. Some engines use a thermostat heater to add electronic control to the thermostat opening(BMW E46). 3. Temperature is monitored in more places on modern cars. Cylinder head temp. Block temp. Thermostat outlet temp. Radiator outlet temp. Ambient air temp. Intake air temp. The computer can use all of those values to control the fan and thermostat heater. 4. The engine inlet might benefit from mixing hot and cold coolant more effectively. 5. Modern engines have recuirculating expansion tanks to get rid of steam bubbles with a constant bleed from the hot spots to the expansion tank. The bottom of the tank is plumbed to the water pump inlet. You need a high pressure expansion tank to do that though. 6. A complete redesign of the waterpump system might include 1 or 2 electronically controlled pumps to maintain perfectly consistent flow through the engine regardless of how much water is passing through the radiator.

One problem I see with a multipass is that(for an equally split multipass) there is 4x the restriction for a given area. There are half as many tubes in parallel, and twice the distance to travel through the tubes. Another issue might be that the second pass is too cool to transfer much heat.

Tony, I thought I remembered the same thing. But I would refrain until I tested again. The Spal fan appears to show the opposite on their data sheet.

http://www.mouser.com/ProductDetail/Tyco-Electronics/V23134J1052D642/?qs=sGAEpiMZZMtSzCF3XBhmW%2foU1yPuOCZA7Rkc%252bhjhbI8%3d $10 TYCO Power relay F7 series, number V23134-J0052-X429. Ford(focus ZX3?), Mercedes(midsized sedans), Dodge(?), etc all use them for starter relays(they sell for $50 as factory replacements). I also like the F4 series but high ambient temps will reduce capacity by 25-30%(which is less than required by the high speed wire). The relays do not "burn up". They do not even get hot. The contacts get dirty and they fail to switchover or activate. Tap on the relay and/or cycle it a few times and it might clear up... temporarily. Once you get a resistive connection the relays WILL BURN UP. You will have relay failures at a fraction of the rated cycles when improperly applied. Most of these relays are rated at 100,000 cycles. I'll be you don't get 10% of that before failures. The only argument FOR ignoring proper circuit design is acceptance that the relays are incredibly long lived. You might not see 1% of it's rated cycles before you build another hotrod. Many people have blamed cheap relays for certain manufacturer's fuel pump and other issues. It is more likely power circuit design not relay design. I have had fan relays fail. It really sucks when you can't run to the Walmart fog light shelf and get a new one. Dual fans will work with foglight relays. The sockets for high current relays are also unique because of their 3/8" spade terminals. This also makes it hard to get a replacement to fit unless you can find it at the Ford or Mercedes dealer.

http://www.summitracing.com/parts/RNB-620-101/ is the Taurus fan I am talking about. It costs $170 from Summit and is 3 times as powerful as most aftermarket 15" fans. RB26powered, That SPAL fan is at least 400 watts and should do the job of cooling a big engine. It is a small dia. though and should be used with a shroud.

In order to allow switching between wires, the output devices would need to be a current source, not a current sink like the SPAL PWM controller. The real deal would be to design a PWM that could provide the currrent needed to run the high-speed wire. There are DC motor controllers available for 50 AMPs continuous, but they cost more than the fans and require an entirely separate controller to monitor temps and respond accordingly. Remember that MOSFETs are DIODES so they self protect unless you open the circuit. Then they self destruct. As far as relay protection goes, we need to remember that these are high power devices. Protection requires high power parts. A diode would be king, but the freewheeling fans can generate enough current to fry most diodes without a limiting resistor. The more resistance, the more arcing at the contacts. A capacitor and relatively low resistance ~might~ do the trick, but determining the optimum values will require experimentation. AC pulses from the unused wire can overheat this type of supression. I should hook up the scope and get some data... Soon maybe.

heheh.. I thought of a few more things. A marker flag on a 4' tall flexi pole would aid in finding the little cars in parking lots(full of 7 foot tall suburban assault vehicles). A 3rd brakelight mounted on the roof(as high as possible so it is visible through the windsheilds 2 SUVs back). Train horns http://trainhorns.net/ DRL foglights and driving lights. Replace the fatory seatbelts. Only 5 years lifetime for sanctioned racing, Why would anyone rely on the antique Datsun seatbelts. Door reinforcement. Already mentioned, later years are better. Full chassis reinforcements without a cage. Check out the head-safe cage with roof reinforcements http://www.modified.com/features/0611sccp_opera_performance_nissan_350z/index.html or the S2000 http://www.modified.com/features/0611sscp_opera_performance_honda_s2000/index.html Floor/footwell reinforcements, This is something I have seen discussed before... John C. ???