The Dodge Challenger Message Board

Hi,

I'm looking at the MSD product line for my soon to be rebuilt HP street 440. What I want to do is to control the ignition curve throughout the entire rpm range, i.e. have the possibility to set unique ignition advance on each, say, 100 rpm. As I understand it, the 7-series digital boxes will do the trick together with the software they provide. However, I spoke to their tech support yesterday and they said the 7-series is for racing only. I asked what hinders me from using the 7-series in a street application, and they said there is too much heat generated, and the box will only put up with this for a few seconds. Does this make sense to you? Is there any other manufacturer who offers similar digitally controlled equipment? Am I the only one wanting to do this?

(Maybe you're thinking 'dude, why would you want to do this?'. I just think it would be fun to have the complete digital control. Why settle for a mechanically controlled ignition curve? I'm a software engineer and want to play in my home field, so to speak.)

Fredrik

Yes there are systems that allow you to do this. I can't name one off the top of my head but search around on the web.

I see that MSD do several flavours of ignition control "boxes". Are any of the others any good to you?

I am sure I remember Accel or someone making such a device. I think they are all basically digital retard units. Some can retard more than others.

Personally i think it is a waste of time. People that know me know I don't like expensive toys where the benefits are minor and outweighed by the costs.

These units adjust timing by 0.5 a degree at a time. But you probably wouldn't notice just a one degree change. Two degrees you would notice if the engine had been JUST "pinking".

Remember your initial will be between 14-18 degrees BTDC and your total about 34 degrees at 3000rpm. Meaning there should only be 16-20 degrees in the distributor.

You want at least half in by 2200 rpm.

But all of this is probably all below your stall speed. If you had a hot engine and going up a steep hill where pinking might occur i would bet your engine would be doing around 3000rpm anyway. So total timing is the most important factor and you don't need a computer to set that. Just adjust it until it pinks and then back off 2 degrees.

The MSD distributors come with a choice of 6 different advance curves and combined with 4 different advance stops that makes 24 different advance combinations for you to play with. Plus they give you charts so you can see in advance what the timing curve will be for any given combination.

I will be trying one heavy silver and one light silver advance springs combined with either a blue or black advance stop bushing. This will give me about 17.5-21 degrees in the distributor and an initial advance of 14-17.5 degrees. Total timing 35 degrees.

Just remember that you are really only interested in the timing between your stall speed and 3000rpm.


Now I have said all that I want to say that if you had a good fuel injection system then a laptop programmed fuel and timing curve computer would be essential of course. THAT would keep you busy on the laptop.

Freddsjunne, I use a MSD 6 series on the street. It's got way more power than you should ever need, combined with the Billet dizzy it offers a lot of adjustment, you have a carb? Heck, why not go DIS? Electromotive makes a great setup and with the "laptop" you can adjust almost every parameter which governs advance and rpm in individual timing/rpm cells. They make a system which works for carbs or F.I. and is right up your alley!

Ah! That is what I was looking for Eddie. But then I gave up. I don't like seeing money wasted on stuff you don't need.

Yeah Dave, it's not going to give you additional power just adjustability, and possibly a headache but the man likes to tinker and who knows he may find that majical combo! It is very expensive,(the electromotive equipment, Fabian would get a stiffy over it!), but professional grade. My challenger has a M.P. dizzy,(mallory), orange box concealed, 16 degrees initial 18 mechanical, all in by 2800 RPM. Also Jacobs electronics touted they had the most "power" and some adjustability,(RPM), not timing. It also can be used on the street and is "driven" by capacitors like the MSD,Crane,Accel ectt.

I ran Jacobs gear for years and just sold it recently. That was back when Dr Jacob was still running his own business. I guess he sold up to retire a few years ago?

I have bought an MSD unit solely because I need two rpm limiters.

Now you put a lot of thoughts into this newbie's head There are two big questionmarks to me:

1. What I make from what you are saying, combined with the Electromotive info on their site, the setup including a control box, a coil and a distributor is outdated by distributorless systems. Pretty much like a carburator is outdated by injection. (Well proven, but no longer the best option). Is this so?

2. Why it is only interesting to control the ignition timing below 3000 rpm? At 6000 the pistons move twice as fast while the fuel burns, or explodes, at the same speed. It seems strange that the optimal ignition advance at 3000 is the same as at 6000?

Excellent questions that Dave would probably give a much better answer. The obvious reason to eliminate the mechanical elements such as distributor is that it simply is not precise enough to control, while an electrical circuit is. The engine will not make any more power if you keep advancing it past it's needs. say 34 degrees at 3000 rpm then keep advancing it until it's 60 @ 6000 rpm. Cruising, yes, under load NO! For the same reason I am surprised that some production automobiles still use a starter motor to start the engine when it's not really needed either. Fredsjunne check out Moparengineswest they use exclusively the FAST/electromotive DIS/TPI in both batch and sequential with coil packs incorporated onto the valve covers. They built a 528 Aluminum Hemi with EDIS and it produced more power under the curve than a carbed version and would idle at 750 RPM pretty smooth, in fact with the huge roller cam they used it would be impossible to use a carb and dizzy and have it idle that low. They have a lot of great electronics info on their site and Richard Nedbal is a retired electronics engineer with the auto industry.

I will try to answer this but I am just making it up as I go along. the truth is I DON'T KNOW!

I would guess it depends on the fuel you use.

Petrol will only burn at a certain rate that depends on the octane level in the fuel.

The lower the octane the faster the fuel burns so the less timing advance you can use. Alcohol and Niromethane both have a very high octane level and they burn very slowly and so need a lot of timing advance at high rpm. Indeed up to 5500rpm.

Good high octane fuel is hard to come by. If you can get it everywhere you go you might be able to push total mechanical advance a bit higher than 3000rpm. Maybe 3500. But racers all seem to like it all in by 3000rpm for some reason.

I guess we should experiment for ourselves.

The amount of degrees mechanical advance I can get away with on the Super unleaded petrol on sale here in the UK is about 35 degrees.

Now consider the vacuum advance.
At high part throttle (low engine load) cruising the vacuum signal to the distributor advances the timing by around 25 degrees on most stock distributors. This is to give better mileage. It will also add more advance at high engine speeds. I think?

But if your mechanical advance is to the max, more advance could make your engine "pink". So if you max the mechanical advance you have to lower the amount of advance the vacuum can give you. Down to about 10 or 15 degrees at most. Or don't use vacuum advance at all. The good MSD distributors do not have vacuum advance.

Have I answered the question? Probably not. But I tried!

I think you answered it very well Dave. But, when will our cars going to be cruising at 2200RPM at 65 MPH with 2.6 final drive ratio, VERY light load so a lot of advance is needed,(up to 60 total), the fuel air charge is very lean? Never, these are performance machines under load often, cammed so they allow a larger quantity of fuel and air, there fore less vacum is produced and total advance. MSD does now offer vacum canisters but I could never get the combo to work,(vacum and mechanical), with a large cam of at least 295 duration with 74 deg. overlap, so I didn't use the can and eventually went with a pro-billet which doesnt have the vac. can. Of course this was in a vehicle that was shaped like a brick and weighed almost 5000 lbs. so it was under load often and the vacum became a liability. I also think with an archaic carb it's much harder to do with a performance engine and large camshaft. With the latest EFI systems it can be done, to a point.

Have you seen the new diesel VW Golf? No worries about timing with a diesel and it does 70 miles per UK gallon.

Maybe we should give up this hobby and just settle for one of those. Less hassle.

Very impressive to say the least. Years ago they sold the VW diesel rabbit here in the states, my friend had one and it would get 40 M.P.G.! was very reliable and darted through city traffic just likes it's name. You are starting to see a lot of VW's here in this country area, where usually European Cars are driven by the doctor/lawyer types. I like them, and yes diesel technology is truly remarkable. 6000lb. Dodge,Chevy,Ford Diesels turning 12's with a few minutes of connections work and a new exhaust! What will I do when the R/T is out cruising and a new BigHorn Dodge Diesel,(turned up), with 4 people inside it want to drag?

Thanks for the answers. I still don't quite understand, but I guess I would if I'd had a little more hands-on experience to relate to. You seem to agree upon having the full ignition advance @ ~3000rpm.

I saw that MSD have what they call a 'Multi-function ignition controller', (partno:s 8979 and 8977) which also looks like providing what I'm looking for. This box can be connected to some of their ignition control boxes and in this way grant the driver control of the ignition curve.

To sum up, it seems there are two main roads to go down to achieve full control of the ignition curve:

1. Full-out MSD usage with this 'Multi-function ignition controller'. This costs $440. A 6AL $260, a coil $50 and a distributor $430. All togehter $1200.

2. Distributorless direct ignition, e.g. using Electromotive. A setup would include their XDI box, $600, two twin-coils providing four cylinders each, 2x$140, crank trigger wheel $40 and crank trigger sensor $80. All togehter $1000.

If anyone sees any pros or cons on these, or has any experience with setting them up, I'd be glad to hear.

I'll either be ruined or bankrupt.

That is a lot of money for little gain. I would keep it simple and spend the money on something else.

freddesjunne wrote:I'll either be ruined or bankrupt.

What is the difference? Two different temperatures in Hell?

Exactly. or

Fredsjunne, you forgot with the electromotive system you will need additional sensors as it's an fuel injection system which eliminates the dizzy, fine. You will still need the sensors such as TPS,MAP,MAF, wide parameter O2, and possibly others. The electromotive controls Both the timing and fuel delivery. The MSD governs or controls ignition firing only. Two different systems there. Better price those sensors and dont forget the wiring that connects it all. If the electromotive was cheaper than the msd ready to run, everyone would be using it!

[quote="airfuelEddie"]Fredsjunne, you forgot with the electromotive system you will need additional sensors as it's an fuel injection system which eliminates the dizzy, fine. You will still need the sensors such as TPS,MAP,MAF, wide parameter O2, and possibly others. The electromotive controls Both the timing and fuel delivery. The MSD governs or controls ignition firing only. Two different systems there. Better price those sensors and dont forget the wiring that connects it all. If the electromotive was cheaper than the msd, ready to run, everyone would be using it!

Are you sure? It sounds like you're describing their TEC3 system? I'm considering the XDI, which seems to be an ignition control system only. This should suffice with some kind of crank synch system, shouldn't it?

I think the system you describe is for class racing that must use a carb. And Mechanical Fuel injection like a sprint car engine. The complete fuel/ignition system is the only way to go. What's the point in having a fully adjustable,(base timing and mechanical plus vacuum), timing mechanism and still have fuel distribution problems which are inherent in all wet flow systems. Low and mid speed power can be made superior to any carb using a MPI TPI DIS system. The controller only approach is a lot of money time and equipment for very little gain using even the finest race carbs. If my car wasn't rare at all, I would be interested as you are in a fine system such as the Jacobs, MSD, or electromotive. Peak power is a different story, I am discussing "power under the curve" low to mid speed torque and efficiency. This is why there are 650Lb. Ft. Torque Diesels that achieve 22 mpg at 6000lbs.(the sophisticated injection and electronic controllers). What about using a fistful of power valves, Jet Max Holley jets, accurate to .0001, and an LM-1 meter with a Lambda or Bosch Wide band Sensors, both attached to the collectors and you can "tune" to your hearts with a MSD dizzy and MSD adjustable controller. With the LM-1 you can adjust your fueling parameters based on your measurements at different speeds and engine loads, then you could "plot" your fuel air ratio and your spark curve and make adjustments based on your data collected? I also realise that diesel fuel is approx. 10-15 % more thermally efficient than gasoline,(BTU vs. BTU). This summer I plan on getting a base LM-1 for my bungs!

Alright, I give up, I'll settle for the 6AL until I understand things better. Thanks for all the info.

/Fredrik