Hello David,

Earlier in this thread Dodgeman explained that the -11 on the end of the plug number meant that it's gap is 1.1 mm [or .043"]. These mpg plugs have a -13 suffix so they are designed to be gapped at 1.3 mm or .051".

Mike

What is the gap spec for these plugs? I believe they are intended to be gapped before installation. So don't trust the gap they came with at the factory.

The FU engine locates the spark plug closer to the center of the cylinder, which is superior to the regular head.

I finally installed the "mpg" model plugs. Looking at them next to the [one heat range] colder standard plugs I took out, it appears that I will gain a bit of extra compression [every bit is welcome!] as the projected tip extends deeper into the chamber. The electrode is also of the "side gap" variety and has a slightly larger .051" air gap than the standard plug.



I installed the first one with clay on the end to check for interference with the piston crown, and it cleared OK. I was worried about contact because I am using flat top pistons where dished pistons were originally used with 990 mpg head.

I can see the alternator driven off the propshaft saving power on race cars but not in top gear cruising. revving hard in lower gears will have less drag/load from the alt due to its spinning slower than the motor in those gears, but in top gear cruising it would cancel out and voltage drop from the long wiring would also hurt.

u could save fuel slightly at idle from no load from the alternator, but after a long time the load would increase when driving to recharge (as dodgeman already noted), and the best way to save fuel when idling at lights is to switch off anyway.

If you dont want the A14 you could do the opposite and install an a12a crank 70mm
stroke with e15 140.08mm/5.537 inch rods and 77mm Honda EL 27.5 comp height pistons.
This will need the crankpins machined which will cost about 100USD in your currency
and then youll have the 40mm crankpins 7mm or so longer rods and lightweight pistons.
Youll end up with 1304cc and the benefit of a higher rod stroke ratio for efficiency
by getting all the energy you can from each powerstroke.
Alternatively you could have the a14 crankpins offset ground for 72mm stroke
that will give 1341cc but will use higher octane fuel. However you might want to
just get a cheap a12a crank and the other bits first to save having the car out of action.




70mm stroke will give 2.001 rod stroke ratio
1.520 mm not including head gasket
72mm will give 1.946
0.520 mm not including head gasket

This will mean youll have the a10 like rod stroke ratio
but with more capacity to help up hills and smooth take off.

Ignition is also very overlooked for lean mixtures.

With the electrical theory
itd be better to charge the alternator when breaking but will
need a big AC alternator with yellow top style battery so it
takes the charge quickly when breaking. Also I doubt you do
much breaking in your trials if you can avoid it :) ?

John,

Thanks for the insight in your last post. Lots to ponder there. I'm not sure if I can run as lean as you mentioned. I know I ran 17 to 1 A/F when I was jetted too lean last year and the car surged and really lacked power. I agree that my missing EGR system is hurting my goal. The only reason I'm not using it is because of the header [and I don't want to weld EGR fittings on my header].

Re: the alternator discussion, I agree with Dodgeman.



I was able to get just the right size belt tonight to connect my crank pulley to my water pump. That power robbing alternator [and fan blade] are now removed. Nice weight savings, but it was somewhat offset by the heavier [40 lb.] deep cycle battery.

Mike

The alternator being driven from the pinion looks interesting, but I wonder what advantages it offers.
It takes power to drive it & that power is coming from the engine, via the clutch, gearbox & drive shaft. Instead of sucking that power from the crankshaft pulley, it's now being sucked off at the pinion. Either way, the power is being drawn off before it reaches the wheels.

Naturally, we can point out that it is driven more slowly by a smaller drive pulley, but that's what race pulleys on engines are for & in most cases, the drive shaft is driven at engine speed when in top [or 4th] gear. In 5th gear the drive shaft is overdriven against engine speed, thereby negating the drive speed reduction to some degree.

What about when the throttle is closed, as in descending a hill?
Well the retarding force is a combination of all loads, including engine drag, & the drag of anything normally attached to it. All we have done here is to move the alternator drag down to the pinion, but it's still there sucking out whatever power it was going to anyway.

In my view, in a comparison where the drive ratio is the same between engine driven or drive shaft driven alternators, the power or drag saving is Nil whenever the car is in motion in cruise mode.

What about when the car is stationary, or when travelling slowly in a lower gear.

Well, if the alternator is not charging, then a power saving will result, but the battery is now discharging. If the battery discharges to any significant degree, then the alternator will need to provide additional charging current to top it up once enough speed is reached. This then imposes additional electrical load that will eat into whatever fuel savings were generated while idling in traffic.

Running without the alternator at all & relying on the electrical capacity of the battery is probably the only successful method here. Not practical for general usage, but quite practical for short term temporary use such as in this event.

Oh yeah, it probably goes without saying, but a good vacuum gauge, preferably a large diameter one, will prove to be one of your greater assets.
Just keep that needle as high as possible into the vacuum zone while driving. If not, then just about everything you do will be compromised by potentially a less than optimum driving technique.

With regard to heating the fuel way up so it vapourises (and this in part is what smokey was doing with his 'hot air engine', and he did it with fairly crude (by modern standards, but that does not mean that they were crude in outcome/result), anyhoo, it ends up producing a heated and dissosciated fuel source that ends up having a much higher octane rating than what the gasoline in the tank started with.

I'm not going to pretend I know this stuff intimately (I've read smokeys patents and articles and believe I could reproduce it but wouldn't necessarily be able to tell you every last detail as to _why_ it works!). BUT on the yahoogroups mailing list called 'jyturbo' or possibly 'carburetedblowers' (he posts on both so it has to be one or the other). There is a poster by the name of 'meangringobob' who is literally a rocket scientist (designed guidance systems for missiles iirc). He has written about it in one of the mailing lists/groups. If you join them both and do a keyword search on 'meangringobob' as the author and 'producer gas' as the term to find in the message body, you'll find the relevant threads.

It's definitely got potential. He's also done some other stuff like on an old smog era motor with particularly low static compression, he actually uses a very mild concentration of diesel cetane rating booster to result in a fuel that has a more complete/quicker burn and actually makes the otherwise 'terrible' combustion chamber shape and comp ratio of the large bore big block ford (FE maybe?) and gets decent improvements in economy with no downside. Obviously that would be suicide for a higher compression engine with a quick burn chamber, but it's an insight into the lateral thinking abilities of the man. It's probably worth a look.

Without a doubt the use of a windmill driven alternator would only result in a minor improvement, as the amount of energy needed to be replenished to a battery after starting and whilst driving (well unless it was at night with extra headlights and a stereo or something). I dare say it could be located in a place that wouldn't increase the overall aerodynamic drag enough to cancel out the gains without any major drama. Heck - what about a solar panel moulded to the boot (trunk in north American countries??) lid. Would be by no means financially 'superb' (they aren't cheap and require regular cleaning and so forth, but on a technical level the amt of fuel used to recharge/maintain the battery would be reduced...

On most gasoline based fuels (assuming a stoich around 14.7) leaning out all the way to around 17-17.5:1 tends to see ongoing (albeit levelling off) improvements in bfsc. The reason is fairly simple for that. Aside from an overrich mixture burning a little slower, you could look at leaner fuel content in a different way - look at it as having more _air_ for a given amt of fuel. This is important as it provides more volumetric efficiency, so more running 'actual' effective or whatever you call it compression ratio, so a more productive burn, and furthermore, more air in there that gets heated by the burn cycle, so it pushes down on the piston for longer before the ever increasing cylinder volume bleeds off the pressure till it no longer is of significant effect.

If you wanted to stick with 14.7:1, for arguments sake (and I wouldn't) believe it or not, a properly configured egr system will introduce what are effectively (well close enough to in the scenario/time frame they are in the cylinder) inert gases, so there's more dynamic/effective compression, without the a/f ratio being too lean to fire. This is the method I'd maybe in a pinch try if I didn't have a particularly strong ignition system. (note I said 'try' - I'm not certain it'd be totally rewarding).

Anyhoo, out to around 17-17.5:1 tends to be about the limit. With a powerful enough ignition system, you could probably light off mixtures leaner than 20:1, but from the testing/data I've seen (which mostly surrounds NACA reports at this time, and some other aviation related links) the gains just dwindle off, so there's no advantage going much leaner than that.

Oh and I forgot to mention,

I really wish I had an A12A for this car! The A14 still has far more power than I need for this type of competition. It's better to have the throttle open further to reduce pumping losses.

Gentlemen,

Thanks very much for all of your thoughts and input. There are some great ideas in this thread. I am starting to get things together and will soon post updates with pics. I have decided to go with removing the alternator completely for this event and have installed a new deep cycle battery. Obviously, I now want to lower every electrical load I can. I started with [temporarily of course] disconnecting the choke thermostat and fuel cut solenoid. I adjusted the choke wide open and removed the pintle from the fuel cut solenoid [so it will still idle].

I am fitting a shorter belt that I will "jump" onto my single row crank pulley and water pump.

I also bought two large sheets of choroplast [sign making material] that I will use to fabricate a smooth belly pan out of. Both side mirrors are deleted [again temporarily] as well as both wiper arms. The plexi glass headlamp covers will go back on as well as the 1/2 grill block and front chin spoiler from last year.

Lots of work and testing to do before the event on August 23rd. I will reinstall my wide band setup and try to tune it a bit leaner than the 14.7 to 15.0 to 1 A/F ratios that I ran last time out.

I will again be running 100 octane low lead aviation gasoline for the event [and throughout testing of course]. It has the advantage of having no ethanol added and is required to be "certified pure" for aviation use. I simply need it for the octane due to the higher compression, advanced ignition lead, hot thermostat, and hot air intake.

Mike