Electric water pump and power saving?

Road-race engines and ancillaries - general discussion
nabihelosta
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Re: Electric water pump and power saving?

Post by nabihelosta »

Guy

You probably gas-flowed the E46 M3 head, Engine code S54B32 (3.2L 24V 343bhp)

By far, this is the best head built ever by a mother company. Straight shot ports all the way to the valves, polished like nobody can do better. "Hidden" bronze valve guides, ultra-light valves (38mm In - 31mm Ex), 5mm valves, titanium followers, stock 272deg camshafts with 12.4mm of lift, could be upgraded to 304deg hi lift (13.3mm) Schricks. Without mentionning the stock 50mm ITBs and the huge airbox. The engine delivers its 343hp (in Euro specs) at 7900rpm.

107bhp/Liter stock IS something. no?

(P.S: Really nothing is perfect. Those wonderful power machines tend to throw a rod in their first 50.000 Kms. We've seen that too much! Brutal down-shifting is a NO NO!)
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Guy Croft
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Re: Electric water pump and power saving?

Post by Guy Croft »

Ah, OK, thanks Nabil

That is something, yes!

G
nabihelosta
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Re: Electric water pump and power saving?

Post by nabihelosta »

Guy I'm sorry we really drifted that discussion from its initial subject.

I just want to give a last credit for you. Being a Master in race engine building, like you are, is when you build race plants from scratch, and very normal road engines, with lots of experience and trial and error.

We will never have that much credit, as BMW gave us a huge amout of stock performance to start with. So we do start in halfway, where you have already done a lot of work and thinking to reach. Our job is really much easier than yours.

And that means RESPECT :-) A Master will always be a Master, and not less. Thank you.

(P.S: I really experienced how much your job is trickier than ours, when I rebuilt my own Fiat TC engine. It was a very tough adventure, still, I can't get the power I was hoping for!)
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Uros Piperski
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Re: Electric water pump and power saving?

Post by Uros Piperski »

We're still waiting for those photos of your engine, Nabih!
TS131Volumex
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Re: Electric water pump and power saving?

Post by TS131Volumex »

Nabil ,
Sounds like a great race series you are involved in .
Please explain what are the advantages of running the alternator off the drive shaft ? You have shifted a small amount of weight rewards and the alternator is now being spun relative to your gear selection but surly the drive/ prop shaft is just the other end of the crank nose so to speak , I feel I have missed something here . Matt .
nabihelosta
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Re: Electric water pump and power saving?

Post by nabihelosta »

Matt

I'm going to go a bit informative and scientific on that.

Yes you're right, it is the other side of the crank, but you missed the fact that it is AFTER the gearbox. So it is driven after the gear reduction of whatever gear you are in: 2.4:1 on 1st, 1.8:1 on 2nd, 1.42:1 on 3rd, 1.17:1 on 4th. It only equals the crankshaft rotation on 5th gear, which is in this case 1:1, but which also is NEVER usable on our hillclimb tracks. Even the 4th gear is usable for some 30 seconds in the whole season.

So, profiting from the gear reduction, and mostly being after the flywheel, the drag forces are much reduced on the engine, which helps on improving the torque curve by raising, flattening, and coming earlier. As per mechanical theory, peak torque of the engine is when it can "trespass" all the force needed to drag its auxiliaries and internals, frees itself, and concentrate all the power on dragging the drivetrain alone.
Imagine a standard factory M3's engine: It needs to drag its valvetrain first, then water pump, viscous clutch fan, alternator, AC compressor, power steering pump, secondary air system pump (anti-pollution), a 2kgs front vibration damper, and a 12-13 kgs flywheel.
Then imagine this very same engine, dragging a lighter valvetrain (titanium valves), electrical water pump, no engine fan, alternator reduced at the propshaft, no AC, electrical power steering pump, no anti pollution, a 600g vibration damper, and a 3.8kgs flywheel.
Now can you see the difference?
Now raise the CR from 10.8:1 to 13:1, lighten and balance the bottom rotating internals, put bigger valves, port and polish the head, upgrade and lighten your valvetrain, go from 260deg camshafts to 316deg, add full equal length extractors, dismiss the mufflers, add bigger injectors, manage everything with a Motec engine management.
Now FEEL the difference :-)

P.S: Photos are to come soon. Very soon. May be going for a sequential gearbox this season (fingers crossed! 16000USD) or at least a Dog-Leg.
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TS131Volumex
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Re: Electric water pump and power saving?

Post by TS131Volumex »

Thanks Nabil , I Infact pointed out the ratio aspect but was at a loss to any other reasons . Thinking about it , it must make engine removal/maintenance much simpler the less that is attached . Please could you include detailed pictures of the alternator set up incase I need to take that route .
Thanks . Matt .
T. Christian
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Re: Electric water pump and power saving?

Post by T. Christian »

"How much" power may be freed up is a big variable with many dependents. The curve probably wont be impressive. On engines with less than 100hp, even 2% sounds nice. I'll try to address the general street car. Competition engines are for competition.

Converting rotation to electricity and back to rotation is less than ideal. It does allow storage of scavenged intertia for release when wanted.

To increase engine cooling, less engineered (earlier) designs simply added more coolant to the system regardless of load to the pump or the entire vehicle. Effeciency of the coolant flow in modern engines has become quite optimised in most. Contemporary design considers pump type and many engines have developed evolved coolant flows regardless of type.

Where electrical systems can be best applied is with "intelligent" control. Heat scavenging in the form of flow control can benefit combustion efficiency. Variable thermostats, controled thermostats, and the elimination of the thermostat (relying wholey on pump controls) are effective heat control options. These remarks are to address that the option of modifying the system in part or as a whole can at times create power aside from reducing the power used in ancillaries.

Engines with traditional coolant flow designs can benefit from a compact electric motor in place of the pulley which drives the pump. This can have a variable speed with simple solid state control and the elimination of the thermostat may be considered. I am unaware of such a pump being manufactured for the Twin Cam. I'm sure a vendor would make anything you pay them to.

Yes, a clutch is a viable idea. A consideration of the mass loading down the engine when it is engaged may outweigh the small gain and clever engineering effort.

***Serviceability can influence a reliable option more than any other percieved benefit.

Thanks everyone for making this a great site!
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WhizzMan
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Re: Electric water pump and power saving?

Post by WhizzMan »

I'd be cautious as to reducing coolant flow in an engine, unless it was very deliberately designed to allow for that. You'd want your engine to warm up quickly, which requires warmer coolant to be pumped to colder engine parts. Once your engine is warm, you'll want to avoid cavitation at all costs, so at least the head should get an adequate amount of flow, regardless of what other parts of the engine require. Unless you design in several thermostats that will reduce flow to the lower engine if it doesn't need more, I doubt you could do much with flow reduction to separate engine parts.

I do see a benefit in doing actual temperature measurements inside the head. You could delay heavy pumping a bit after stepping on the throttle, because the heat will take a few seconds to travel to the area where it gets transferred to the coolant. This would also mean that you'd have to keep pumping coolant a bit after the throttle has closed, since you have built up heat you need to get rid of. This may be where the most gain can be made. In unregulated systems, you need the flow to be always the minimal required, so even at idle, you need enough flow to cool down a head that has just seen 10 minutes of intense, full throttle action.

The biggest gain for a race car in my opinion: By using a generator, battery and electrical pump, you can store electricity harvested at not full throttle periods and effectively not have your engine convert part of it's energy to electricity at the moments you really want to get 100% out of it. Simply make the alternator stop generating electricity at over 95% or so of throttle (electronically disconnect the field coil) and gain some extra power. Be aware that this will make your on board voltage fluctuate, so make sure your electronics can deal with this. Injection systems have a compensation factor for this voltage, but it tends to be rudimentary in a lot of cases. Fuel pressure and injector opening time can be influenced, so do your homework if you plan to do this.

These strategies are already used on race and road cars and might be adaptable to more DIY levels of race and road car technology. However, I'd be cautious about reducing flow on DIY projects, calculating and measuring the required amount of coolant requires expensive equipment, software and a lot of trials.
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nabihelosta
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Re: Electric water pump and power saving?

Post by nabihelosta »

Sorry it's been too late since my last post, but we got caught into the worst weather storm ever to hit the country, snow was everywhere, so we didn't do much on the car.

This week we re-started our preparations, as the first hillclimb is taking place on 29-4. The Dog-leg gearbox will be arriving this week.
I will post some trial fitting pictures of the alternator. We altered the fitting position, moving it to fit at the rear diff cover, and driving it with a pulley attached to the CV joint flange, the one that fits in the diff.

I tested it yesterday, jacking the car and starting it. The charging light turns off at 55km/h for the 1st time, then keeps charging (14V constant) even when the speed drops to 25km/h. Pulleys ratio is 3.75:1.

Enough talking, here's the pics. (Sorry for the bad quality of the brackets and equipment, it's only a trial fitting. Final brackets will be made from Dural alloy.)
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WhizzMan
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Re: Electric water pump and power saving?

Post by WhizzMan »

If at all possible, I'd measure the amount of charge your battery loses during a race. You are looking for a setup where you can at least finish the longest race you will be doing. The car I've seen with a similar setup, had a smaller pulley, but it needed to last over an hour on a motorcycle size battery, so the generator really had to provide all power for the car. You may actually be able to get away (if regulations permit) with a small battery, no generator and an extra battery held by a crew member for starting the engine. You don't really need a generator for a 1/4 mile sprint, do you? ;)
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nabihelosta
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Re: Electric water pump and power saving?

Post by nabihelosta »

Whizzman

Regulations permits every mod you can do to raise the power, except for exceeding a certain engine capacity (3000c.c.) in my class. The class by itself is called "Super Modified Prototype".
I sure don't need a generator on a quarter-mile drag strip, but my race is a 3 to 4 miles stretch hill-climb, so a generator is a must. Although I use a 200Ah compact lightweight racing battery, I can't let the voltage drop below 13.8V under any circumstances, otherwise I will encounter very serious problems with the M800 Motec engine management.
So I came out with this idea! Fingers crossed for this soon starting season, hopefully I don't lose a belt due to jumps or some road stones coming from under the tires.

Nabih
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TomLouwrier
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Re: Electric water pump and power saving?

Post by TomLouwrier »

hi guys,

Sorry, but I don't see the point in this. The electric power you need to run the car, plus the losses in the generator, is what you take out of the drive line. The further down the line you take it off, the more you losses you encounter in transmission and such. Power is power: torque x revs. You're not getting any for free, just losing some every time you transform or transport it.

You don't have to do multiple cold starts I think, so you might optimize a bit on a smaller/lighter battery and maybe a smaller generator. Also you can play with the pulleys in order to run the generator near its most efficient speed.

But all of this is really small fry compared to the engine's output end even the car's mass. Why bother?

regards
Tom
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nabihelosta
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Re: Electric water pump and power saving?

Post by nabihelosta »

Tom

You may be right on this. If I go the way you are explaining, I might save say half the power losses that occur from a traditional alternator setup.
Though, I chose to do this mod mainly because it's really easy and cheap. It costs me a 50-cent steel piece to make a bracket for the alternator, and some 2 hours of pleasant work of accomplishing a neat job. Plus, should it save me as little as 1bhp, I will do it. I need that 1bhp here. My engine is on its limits for power, no extra bhp could be taken, and I'm on the limits of weight, exactly 980kgs without driver, fuel, oil and water. The thing is that I can remove some extra 5kgs, but I keep in mind that if the car reached the scrutineers with a blown radiator or coolant hose, or a punctured sump (after a stage), it will lose minimum 5 kilograms of oil and/or coolant, it will become 975kgs, so I will be disqualified with no points at all for the whole event.
A pleasant plus I realized last year, is that with this mod, weight distribution in the car became a perfect 50/50. With an 85kgs driver seated in his position, a full fuel tank (8 liters), I had on a 4-wheel separate-pads scale those results: FL: 270kgs, FR: 269kgs, RL: 268kgs, RR: 267kgs. It was like a dream! And my car was 983kgs dry before the mod, it became exactly 980kgs as I saved 3kgs on the copper cable going from the alternator to the battery (trunk).

For the guys asking why be so demanding, the competition is really, REALLY tight. All the cars are in the 400bhp region, all are as near as possible to the weight limit. As for my car, the national press and car experts consider it the most balanced car by far, simply the winning car! Don't forget that I'm the title holder for 2010 and 2011. Proof is, I won the rear-wheel-drive overall title, although I'm in the SM4 class (under 3000c.c), competing and winning against 6 guys with SM5 cars (3000-3500c.c), which all have newer engines (S54 straight six) with stroker kits of 3.5L and huge 450+bhp outputs.
My simple trick is: Keep it as simple as possible, clean neat and easy to service, focus on having the right gear ratios for the specific track, and mostly keep the torque as low/late as possible. Roads here need power at higher revs, torque will only lead me to unnecessary wheel spin.

Thank you for reading this. All suggestions are welcome especially from awesome motor-heads on this wonderful forum.

Nabih
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WhizzMan
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Re: Electric water pump and power saving?

Post by WhizzMan »

200Ah sounds like an awful big battery to me. Are you sure it's not 20Ah? If you have a 200Ah battery, I'd make the generator pulley smaller and reduce battery size to 55Ah or so, that should easily save you quite a lot of weight.
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