SBF Crank trigger

[Ant]

Looking at my ignition system again, used to have MSD 6AL with MSD 8578 Dist and it ran well, now have no ignition system.

General web information indicates crank trigger gives more hp and stable timing. I have also read where there has been no real difference with SBF in hp by testing on the dyno, track etc. My system is dry sump so I assume there will be less distributor timing variation without the internal oil pump drive.

I need an advance curve for some road use, have considered running two systems crank trigger sensor and a distributor pickup to one ignition box, by switching with a double pole switch so I could use the advance curve in the distributor for starting and on the street. Another way for a crank trigger system would be using an MSD 6AL Programmable with a locked out distributor and dial in the advance curves by laptop.

My main objective, is it worth running crank trigger over distributor on a SBF with external oil pump, any dyno horsepower gains or in my case not a straight forward installation with external oil pump etc?

[vector1]

these guys are supposed to have pretty good systems, maybe something you can use.

Innovative Ignition Systems & Components - ICE Ignition

[Gaz64]

I recommended and fitted one of ICE's systems below to a 302 in a Mustang. Owner is very happy with outcome.

7 Amp Street Series Ignition Kit - ICE Ignition

[bobcowan]

The big advantage of a cank trigger system is less spark scatter and more accurate timing at high rpm's, like above 6,500-7,000. Below that, a modern distributor is accurate enough.

The other advantage is that with the right ECU, you can get really good control of your timing curve. For an engine that's fairly radical, better timing control through the rpm range will not only give you more power, but make the engine more efficient. Which can equal better fuel mileage.

[Ant]

Been down the ICE track before thanks.

Bob, my engine is developing over 610bhp at 6800rpms. sounds like a good distributor should work for those rpms. ECU are you referring to e.g. MSD 6AL Programmable ignition box or an MSD 8979 multifunction ignition controller.....?

Crane make a Pro Curve distributor with different electronic advance curves which looks good.

[bobcowan]

If you're making that much power on pump fuel, the engine is "radical" enough that accurate timing is the way to go. I found that I make more power with less timing at the top end than at the middle. And, if you drive on the street, it's a good idea to back off the timing a little bit under a significant load, and add timing under a light load.

For a few years there have been a couple ignition only ECU's on the market, Like Haltech and Megajolt Jr. These systems are really trick, using a computer to control all aspects of the ignition events, and use either a COP of coil pack. Essentially eliminating the distributer from the equation.

There are quite a few ECU's that will control both fuel and ignition, if the engine is EFI.

I have heard good things about the Crane distributer, which combines the ECU and distributer in one package. Not as good as a crank trigger. But cheaper and easier to set up.

Boxes like MDS 6AL don't control the ignition event at all. Their goal is to band -aid the problems of using a single coil to fire all 8 cylinders at high rpm's. MSD does make a retard box, but that just retards timing across the board based on boost or some other trigger.

The timing is based on movement of the distributer. Which is based on movement on the cam shaft. Which comes from yad, yada, yada. You get the picture.

A crank trigger gets the signal directly from the crank shaft itself. No intermediate steps, no scatter, no slop, no changing. Dead on accurate under all conditions.

[Ant]

This engine runs a pro-systems 950 carb which is based on a 750cfm base plate.

That horsepower is a conservative figure when I was assisting with the dyno (NZ) we ran a restrictive air filter and exhaust, and oldish racing fuel. Engine has USA dyno sheets for 675bhp which used 2" spacer block under carb and better exhaust. Looking forward to re dyno with new ignition and premium unleaded, as I dont believe the engine is designed (10.3 comp) to run straight race fuel which is slower burning.
The only thing is with hood height etc I can only run a 3/4" carb spacer although that did make 16bhp difference on the dyno, so the extra high spacer might not make much more.

From your reply as this is a reasonably serious engine and to do the extra work of fitting crank trigger for stable timing to avoid detonation and possibly more power would be well worth it.

This would still bring me back to work out how best to run an advance curve with crank trigger.

[bobcowan]

Originally Posted by Ant

This would still bring me back to work out how best to run an advance curve with crank trigger.

And here is the crux of the issue. A crank trigger that runs a single linear advance curve probably won't help you much. It will certainly be more stable, but you could be missing out on some power and (more important) drivability.

I use an ECU controlled coil pack, wasted spark, and a 36-1 crank trigger wheel running a VR sensor in a custom made sensor bracket.


Megasqirt Photos by bobcowan | Photobucket

Basic timing is based on engine load and RPM. But the basic map is then modified by things like intake charge temp, coolant temp, ambient air pressure, fuel type, etc. The goal is not only to make good power, but to adjust for various conditions on the street, and prevent detonation.

The crank trigger makes sure that the ignition system does exactly what the computer tells it to.

[Ant]

Bob,

Basic timing is based on engine load and RPM. But the basic map is then modified by things like intake charge temp, coolant temp, ambient air pressure, fuel type, etc. The goal is not only to make good power, but to adjust for various conditions on the street, and prevent detonation.
That makes good sense. It would be nice just to pop in a Crane Pro curve and ignition box and keep it simple for a 1965 based road racer.

Found this they have been around for a long time and make this ignition only box. G4 Lightning - Ignition Management — Link Engine Management Systems - plug-in & wire-in aftermarket ECU's

[PLDRIVE]

Ant i would like to hear more about your engine. 675 Brake HP is a lot of power for 10.3 pump gas engine! Please post dyno sheet.

[Ant]

Originally Posted by PLDRIVE

Ant i would like to hear more about your engine. 675 Brake HP is a lot of power for 10.3 pump gas engine! Please post dyno sheet.

[PLDRIVE]

I see now (yates heads).
Thanks