David Hayes

iTrader: (6)

Nice video. Hope to join you soon out on the road.

205F? That's around 96 degrees celsius which isn't the end of the world but for me, too hot, especially when you are not running AC (from what I see in the video). I also assume you are you on B'ham now?

Regardless, those are about the same temps (91-95c) I ran in FL during the summer. And with the AC on, I'd hit a little over 100c. The problem was when trying to track the car, I'd always hit 108-110 in afternoon sessions and would have to slow down to cool off the car.

I still think a v-mount is in your future. Will let you know what difference it makes for me.

Trey, one trick with the stock alternator is to decrease the size of your pulley on the alt. Go to something smaller and it will spin the alternator faster at lower RPMs. This should smooth out your amp issues at low RPMs. The trade off is at increased RPMs, the stock alt might not be capable of handling the RPMs produced (by the alt spinning faster due to the smaller pulley) at that level but I didn't run into an issue when I went that route. I don't know the exact math, but you'd have to run about 8,500 RPMs and above as I recall to have a potential issue.

You can buy an increased AMP alt from IRP. I think it is rated at 140 amps total but that is not at idle. It's reasonable and might work for you. Didn't for me as I had two fuel pumps running at idle and this threw it off. Swapped to a 200 amp unit for Excessive Amperage and that has worked great for me. Costly though at around $400. To be clear, the IRP unit might have worked had I redone my fuel pump setup to have the secondary fuel pump come on under load as I run now.

Monsterbox

iTrader: (6)

Thanks guys!!!!


Believe it or not, I'm using an ebay special. Alternator is rated at 160amps but I had it bench tested at 110a So yes, its pretty much stock.

However, I'm getting nice solid voltage back to the battery, and no charging issues/starting issues. Once in a while I'll get lights dimming if I'm under 900rpm and I hit the brakes but its not too much of an issue.

I can't remember the exact voltage but I want to say it puts out around 13.5-8 at idle.

Make sure your wiring is good! Voltage drop via the stock wiring to the starter was insane! So bad that it was killing batteries trying to crank the car over time. Replaced it with 00 wire directly to the starter and its wayyyyyyyy improved.

t-von

iTrader: (8)

David I have a similar style alternator as Monsterbox. It's a 140 amp ebay special. It already has the smallest pulley on it to make it spin faster. It just wont keep up at idle at all. The thing I hate about this damn thing is, it wont start charging until I reach 2,000rpm before it turns on. So I've had to change my BAC settings so the engine naturally revs to 2k at start up so it kicks in. I could put back the factory unit but its not gonna keep up with all the extra eletrical on the car. Remember the stock is only rated at 100amps. Our 20b swaps have higher flowing fuel pumps and 3 extra coils. Not to mention the extra gauges we put in. Far too many people are running around with heavily modified fd's with the stock alternator. If you ask me their asking for trouble. Plus I have a 5 channel 2,500watt amp in the back. My amp hasn't even connected and it still wont put out enough amps at idle. I have zero issues at 1,000 rpm or higher but I need my engine to idle at 750 for my experiments. My bin mounted battery has the positve going straight to the starter and then to the fuse panel. I even upgraded the the charge wire to 2 gauge. Negative goes to the lower seat anchor and then under the carpet up though the shifter boot and to the back of the tranny for engine ground. I think my problem may be the fine strand 2 gauge wiring I'm using. The cable is basically the same stuff use ona welding machine ground. I'm gonna try to go with a normal automotive style 2 gauge and see it that helps. If not, I'll need to find another alternator.

rx7jocke

Do you use the stock cas or something else? The reason i went with ffe trigger was that the cas aint reliable enough and can give just the symptoms you speak of, no/bad/unreliable signal when to hot (well always). What type of injectors and coils do you use? Maybe its in your thread somewhere but its like 25 pages :-)

Monsterbox

iTrader: (6)

Hmmm...

Thats interesting. I'm using the stock CAS.

So you speculate that when hot, the CAS may not be generating enough signal at cranking speed to signal the ECU into firing? I will check the internal scope on the ECU to ensure that it see's cranking pulse from the CAS. It CERTAINLY seems probable, as the car doesn't fire AT ALL then when it cools down a bit it fires immediately!

I'm using LS2 D581 Coils in Direct Fire

Bosche 1680/Lucas 850 Top Feed Injectors

Walbro 400LPH

Monsterbox

iTrader: (6)

I'm not sure whats going on here.

I have quite a bit of electronics in my car as well. EBC, Gauges, coils, fuel pumps etc and I have no issues with charging that I know of...

Recently I measured voltage coming back to the battery and also directly off the alternator output stud. I was seeing nearly 13.5+ even 14.0v at the alternator, with a minor voltage drop to the battery in the trunk. Maybe the voltage regulator is dead on your alternator?

Its to my understanding that voltage should be able to keep up / adjust depending on RPM. The amperage output may be weak at low RPM, but why should this affect voltage amount?

j9fd3s

iTrader: (3)

you might try logging rpm, coolant temp, charging voltage and injector duty, during one of these episodes

Monsterbox

iTrader: (6)

I def will!

I hate to keep pointing fingers at the ECU but...

When i first installed the ECU. Using the same battery I used on my AEM 13b for years, the CAS would not register on the ECU. No trigger signal input during cranking.

It wasn't until I went up to a 1000ca battery and rewired direct to the starter that I was able to see signal from the CAS during cranking.

The car used to act the same EXACT way. No fuel or spark it seemed. No sputtering. Just cranking like EGI fuse was unplugged. Then once it passed a certain threashold (the filtering of the ecu) the ECU would magically come to life car would fire right up.


So, bets are on the CAS sensor heat soaking, building up a little bit of resistance and showing a slightly smaller sine wave to the ECU, which is filtering out the signal. When the CAS cools down the sine wave gains a little strength back and overcomes the filter.

There's a scope inside the ECU that can graph the wave coming from the CAS if it passes the filter threashold. Lets see what it does! It may be as simple as increasing the sensitivity / decreasing the filtering of the ECU

Monsterbox

iTrader: (6)

thanks! please do take a vid and post it up, why not? I'd like to ride along in your car on youtube

EDIT: Just found one of your vids, in the large picture thread, cruising around the street. Your machine sounds super clean!~

t-von

iTrader: (8)

Monsterbox you may be right about the internal regulator. I also have a totally different hot start issue than you do. When mine is in the 200+ temp range it will try to fire up. It just never catches and my cranking voltage is dropping into the 7volt range. When I put a charger on it to give it more cranking amps she'll start. I even put in a brand new Miata battery from my Miata to make sure my Braile wasn't the problem and it does the same thing. I'm really thinking I just have a defective cheap alternator. I dont think it's putting out what it's suppose to in the very low rpm range causing my small Braile battery to take up the slack in its reserve capacity. Even with my new Rx8 style starter, hot starts are very sluggish. Right now I'm rewiring with some 1/0 Gauge I have from my job. If that doesn't change things, then I will be going with a quality 250amp unit as I'm getting tired of this ****. Lol!

j9fd3s

iTrader: (3)

lol back when i had my 20B, if battery voltage dropped that low the ECU would turn off #paperweight

Monsterbox

iTrader: (6)

Tvon can you tell us what your voltage is directly off the alternator at idle? What is the voltage at idle across the battery terminals? And also, what is the voltage across the battery terminals with the car off?

t-von

iTrader: (8)

Sure will! I also found out some interesting info on our supposedly upgraded ebay alternators. Stay tuned!

t-von

iTrader: (8)

So yesterday I decided that I would put back the factory alternator just to see what it would do in similar conditions. Well the one I had needed to be tested so off I went to Autozone. Well the factory unit tested bad. So I take it to a local alternator shop to see if it could be upgraded to 250amps. After doing some research, I need something this big for my amp. The guy looks at it and tells me "you can't upgrade these to higher amps only rebuild". I was like "well I bought one off the internet that was rated at 140amps". He then says "they lied to you because you can't buy the parts to do the upgrade". I was like WTF??? So Monsterbox, that would explain why your 160 amp ebay alternator is only putting out stock levels. I guess we both bought a falsely advertised product. Lol! This shop can build whatever else I want so right now I'm gonna do a retro fit of an american style alternator that CAN be properly upgraded. My initial quote was about $230.00 for a small body 200 amp unit. At least now I'll have the piece of mind of having someone local to take it back too if it under performs.

rx7jocke

I have also tried to upgrade both the fc3s s4 generator and cosmo 20b generator but got the same awnser, it cant be done.....atleast no company in sweden can do it and they claim that there is no such parts to do so, so i bought a taurus 130amp generator for 80usd at the scrapyard, with 6 months warranty :-). As close to bolt on as it gets.

David Hayes

iTrader: (6)

T-von is correct, you can't "upgrade" the alt without rebuilding it. Here is a link to the guys I got my 200 amp FD alternator from:

Excessive Amperage

They take stock alternators and rebuild them. The also ensure the rebuild can handle the rpms of the car as ours spins at higher rpms. That is important to tell whomever you are using to rebuild the unit, that your car revs higher than most as that means the alt will spin faster as a result.

The beauty of going this route is you end up with an alt that has the stock FD casing, so it's a direct fit back into the car.

rx7jocke

1 more idea could be those 1680 bosch injectors....they are well known in europe for acting really wierd when hot ( leaking fuel into engine when it should be shut such as when engine is turned of, and not flowing enough when opened.) This because its not made for liquid fuel but gas...google it and compare ur issues....i read alot about it in an bmw forum

AdaptronicAus

Hi guys, I sent this to Mr Monster before, but watching the ECU gauges or logging it during a hot soak restart vs a normal restart when she fires up straight away will give us the answer.

When engines are hotter they normally crank faster, faster cranking = higher voltage, so I think it's unlikely to be the ECU not picking it up. Even if the CAS resistance increases due to the higher temperature, the increase would be marginal, and anyway the output impedance of the CAS is so low compared to the imput impedance of the ECU that it would make hardly any difference anyway. I think it's highly unlikely to be an RPM pickup but the log will tell us.

I'm still going with fuel temperature. From the factory the RX7s increase the fuel pressure after a hot restart by disconnecting the pressure reg from manifold vacuum, I believe to reduce possibility of vapor lock (higher pressure -> lower chance of vaporisation). I can't comment on the injectors' function at high temps though.

Monsterbox

iTrader: (6)

Thanks Andy, I believe you are correct. Haven't had a chance to work on the car and log/diagnose but I understand your logic. Don't want to point fingers at the ECU! The hot fuel probably has vapor/bubbles on shutdown

The fuel pump speed controller has arrived from Aeromotive, this should finally solve the vapor lock issue Going to run the pump at lowest duty cycle possible as to not loose fuel pressure @ 3k rpm and below, having it switch back to full current above 3k rpm. This should keep the flow rate much lower, and keep the heat out of the tank, so that fuel remains cools circulating through the rails.

I will keep you posted

lOOkatme

iTrader: (19)

Would it be benficial to install a little heat exchanger into the fuel return line before going into the tank? or would this add too much of a pressure drop to the fuel pressure?

Monsterbox

iTrader: (6)

I have done so already and didn't notice much of anything, but I may reinstall the exchanger for peace of mind.

Installed the Aeromotive FPSC last night. I'm honestly not too impressed with this product either. It doesn't pick up the RPM signal well at all, going to have to wire in a filter (capicitor/resistor). At low speed operation, the fuel pressure drops down around 30-35psi (10volts) and the pump hums along at a low hum. Anything lower than 10v and the pump will randomly stall, requiring a key on/off.

Hopefully 10.5v is low enough voltage to reduce speed and prevent cavitation. We will see once I get a filter on the RPM signal!

t-von

iTrader: (8)

^ Well that sucks to hear. Me I got my custom upgraded 200 amp alternator yesterday. Fired her up and got 14.5 immediately at 1,300 warm up rpms. As soon as my rpms starts dropping towards idle, so does my voltage. It wont put out anything at 1000 rpms and has the smallest pulley available. . I explained to the guy that my fd pulley is only 4-1/4" in diameter before he built it and to make sure it would charge at low rpm. I've already taken it back to see what they can do to get it charging sooner. If this doesn't work then I will have to go with the more expensive Excessive amperage or Power Bastards option.

Monsterbox

iTrader: (6)

What voltage do you consider ok for charging?

I was seeing 13.4-5 at 900rpm last night

Speed of light

iTrader: (8)

Are you running an AGM type battery? If so, those generally need to be charged more aggressively to get them to full charge, i.e., 14.5-->15-ish volts or more (cyclic), depending on battery temp. (Refer to you battery manufactures real tech literature for charging specifics.) Any battery's performance and potential life will fall off rapidly if it isn't fully charging.

I should also mention that the internal regulator in the common automotive alternator is designed to charge standard lead acid batteries and includes temperature compensation or a gradient to reduce the output (charging) voltage as the temperature increases. Now consider that the alternator is in a hot engine compartment: the assumption designed into these internal regulators is that the battery is co-located in the engine compartment and that the regulator's temperature tracks that of the battery; thus functioning as a system to maintain the correct charging voltage.

Therefore, if you have a relocated battery (of any type), you probably need to charge more aggressively to maintain full charge. Again, the reason is that your battery is likely going to be much cooler than it would be if near the alternator and since batteries are properly charged with reference to their temperature, there is now no thermal feedback loop to offset this change to a cooler environment. This will result in an undercharge unless you increase the alternator's output voltage somewhat to compensate. And if you have a relocated AGM battery, you've got a double whammie due to the fact that it requires a higher charging potential to begin with. While a few tenths of a volt may not seem like much, it is a significant percentage to a 12V system and a very big deal to getting a battery properly charged. The complications involved in relocating a battery to a cooler location, however, are usually far outweighed by an increase in battery life--if it is installed properly.

So how do you increase an alternators output voltage by a small amount? Simple, for internally regulated units (like our FDs) you change its reference voltage. To do this, locate the alternator's field/sensing lead that it uses for its voltage reference and to excite the alternator; often times this is hooked to a circuit coming from the ignition switch but it is NOT the one used for the warning light. Cut the wire, preferably near the alternator, and add a small forward biased diode for each ~0.6 volts you want to increase the output. For my own car, with a bin relocated AGM battery (PC925), I added 2 diodes in series to the stock FD alternator's field lead to increase the output approx 1.2 volts (to about 14.8V which is a more appropriate charging voltage for my setup (vs 13.6V without the mod). I used the 1n4001 series of general purpose rectifier diodes as they are small, rugged, work well, and are less than a $1 for both. If you have a super high current alternator, you may need to double them up or use higher current rated diodes; you can measure this in the field lead.

T-von, it sounds like there's not enough field excitation provided by your alternator's regulator and/or not enough rotor core volume. Additionally, regulators usually have current limiting built in to protect the alternator from melt down; while this isn't a problem at speed, you need a lot more field current to get a high output at idle. Since the laws of physics dictate that an alternator's output will drop off with decreasing speed, you have to put more energy into the system and thus into field to make up for this--a technique that works, but has limitations. Real, purpose-designed high output, low speed alternators may also have larger rotors wound to handle this and may be larger in overall diameter (to increase surface speed and/or include more poles).

t-von

iTrader: (8)

13v and up is what you wanna see at idle so your good. Now do you see that same voltage when you start loading up the electronics? That's been my problem with this junky ebay unit. Like tuning on the blower on high, with the headlights, and cooling fans? Your alternator is suppose to supply enough amps at idle with all these things on.

Oh and I just now found another problem thats been plaguing me the last few weeks. Back in December, I upgraded to the IGN-1A coils. Well I accidentally dropped 1 when I was building my bracket. Fast forward to today. I have a spare Nissan Maxima alternator I decided to put on the car to see how well charges while I wait for my upgraded alternator to get re-upgraded. Lol! I go to start the car and it just turns over. I realize then that I accidentally disconnected my ignition coil ground from the block. Based on some info I got recently from C- lugwig, a couple months ago, I separated both sets of leading and trailing coils to two different 12v relay banks. Originally, I had all 6 coils on 1 20a fuse/relay. So when I turned the key over, the car still should have fired up on at least 1 set of coils but it didn't. You see I have both sets of coils grounded in separate locations and only one pack was disconnected. So I plug in that disconnected ground and then check my main Haltech ignition coil fuse. Sure enough it was blown. Hell no wonder it wouldn't fire up because that blown fuse goes to my leading coil packs and the disconnected ground went to the trailing pack. So all this time, I had been running the engine recently strickly on the trailing coils. Engine fires right up and sounds great. While running, this alternator is putting out a solid 13.7 volts at 900 rpms so now I can finally re-tune some things. I go to shut the engine down and restart and same thing. Hard starting and I here a pop. I check that fuse again and sure enough its blown again. I was like WTF! I even put a 30 a fuse in just to see what would happen and it popped as well with the engine off and key on. I go back to the engine bay to look around for a short and see some white creamy fluid comming out of my center rotors leading ignition coil. It was cracked and hot. Well now I know which coil it was that I dropped back in December. My self inflicted wounds are killing me.