|10-03-2012 03:33 AM|
MSD Street Fire CDI Ignition
Fellow Hot Rodders,
I have a 1976 Mercedes Benz 450SL Roadster. I Know, not your conventional "Hot Rod". The engine is a 4.5L OHC Mercedes Benz V-8. There arent a lot of OEM performance parts, so I've had to fabricate most everything. I took tke intake, cut it in half laterally and reworked the runners, polished all the ports and built vortex generators into the runners. I also custom built the entire exhaust including headers. I worked over the heads, porting and polishing the intake and exhaust. Because this is a factory high performance engine from MB (The 450Sl is the little Hardtop/Convertable) the valves were as big as they could be made. Fuel delivery is via a nearly 40 year old Bosch "Jet-Tronic" Direct port injection. Its a hybrid electronic/mechanical injection unit. I massaged that by modifying and installing injectors from a 5.0L Mustang GT engine. I had 2 cams custom ground because you cant buy aftermarket cams for this engine. Its an old 3 speed automatic, so I designed the cams to have good low end torque and power, but mostly to perform over a wide RPM range. This car has a passing gear that will put you in the seat from 40 MPH all the way to 120 MPH. The tranny is geared for a long 2nd gear like this, so I gave the cams a wide RPM range...
Now to the subject... The original ignition was an old electronic single spark Bosch electronic ignition which worked pretty good. Almost good enough that I left it on there for quite some time. However, I recently installed a MSD Street Fire CDI Multi Spark Ignition and I can describe the performance increase in ONE WORD... WOW!!!!!
This little car weighs in at nearly 5000 Pounds, so it never was a quarter-miler, and still isn't. However this ignition increased the low end UNBELIEVABLY. The most demanding part for this engine always has been to get the lead sled moving from a standing start. Its a small displacement engine, so you don't think of a lot of low-end 0-30 MPH pulling power. However, this car is capable of top end speeds in excess of 170 MPH. While the MSD didnt increase the top end top speed, it did DEFINITELY shorten the amount of time it took to get there. Also, in 1st gear, from 3500 RPMs to 5500 RPMs this little (5000 Pound) car absolutely tears #*@& (butt). When it hits the power at about 3500 RPMs the *** end will absolutely dance. But the real difference is in that LOOOONG passing gear. From 70 MPH, you floor it and it shifts down to 2nd gear. By the time you look from the road to the speedo, you're doing 100+. If you hold it in second, it will still shift to 3rd at 6250 RPM and when it does shift to 3rd at 6250, you're doing over 130 and when it shifts it LURCHES forward and again, you look from the road to the speedo and its at 140+ at 4500 revs and the tach is just a blur. The speedo only reads 160 and at this point I don't take my eyes off the road, but at 5500 revs the speedo is pegged out and the car is STILL rocked back on its hind quarters. Unbelievable!!!
The increased performance I got when I swapped the ignition to the multi spark is truly unbelievable.
You havent truly lived until you've been 160+ MPH in a nearly 40 year old car!!
|02-17-2010 02:30 AM|
|SSedan64||You stole those. "Old" catalog prices were Ann 100=$180, Strip 200=$300, Pro Strip 300=$580, ICT 400=$700|
|02-16-2010 08:24 PM|
|ericnova72||Yep, I've got a #800-300 new in box and a #800-400 in use right now. From what I can tell the 300 and 400 boxes are the same, the 400 kit just comes with a crank trigger wheel and pick-up. The #800-400's crank trigger allows you to set the distributor's magnetic trigger up as a cam sync allowing you to use the ICT function(Individual Cylinder Timing). You can do anything imaginable with this ignition. I'm always on the lookout for another NOS set, both of mine have been under $200 scores.|
|02-16-2010 07:32 PM|
Ex: #800-100 w/Rev Limiter >> http://cgi.ebay.com/ebaymotors/NIB-H...item35a71389d9
|02-16-2010 03:22 PM|
there is next to no gain with the swap if your plugs are dry and light brown using the HEI...
cdi trades more Kv (50) for very very low milli-amps (which is spark heat intensity) and has to have multi spark to not misfire at low rpms..
hei is longggg duration spark event at only around 18Kv with .045 plug gap so there is much higher milli-amps "heat" available to light the fire....
both units operate with about 5amps input so for all practical purposes the spark "joules" are the same....
ya do want cdi with a healthy cam on the street,,,the gas is not getting "atomized" well at low rpms due to the cam,,,the multi spark does insure the fire does get lit...
|02-14-2010 02:49 PM|
|02-14-2010 02:05 PM|
|ericnova72||If you really want one of the best, look for the Holley Annihilator Ignitions. No longer being made, but new unused units still turn up in online auctions and ads for real good prices, considering all the features that they offer and the durability. It's sad that Holley couldn't keep this in production and crack MSD's stranglehold on the ignition market, they are the sh**. .|
|02-14-2010 01:25 PM|
Lol I found my typo. Getter instead of get. I sound like Larry the cable guy. I fixed it. I was typing something else and I went and erased some other words and I missed a few letters. I have decided to get a msd to go along with everything else I have put on the truck so far. From what I have read many people like the msd CDI type ignitions and many hotrodders have excellent luck and performance with them.
Take care guys thanks again.
|02-13-2010 10:35 PM|
|sqzbox||Opps! Who can spot the typo?|
|02-13-2010 09:02 PM|
Well I guess if I did take away the question mark that kind of answers my question on the most part on paper though. But real world results is what matters and what kind of experience I get. I might get one but am undecided yet. I have had my 350's on both trucks cranked up to 65000 rpm with no issues what so ever and no misses.
The only misses I have had is with my plugs being the culprit. I just want to get best burn on my plugs as much as possible. I am learning many things on tuning carb's and thats fine tuning not just basic and run type thing. I have my timing and distributor curve done nice and good and I just have to change out my sping in my vacuum secondary to open up a little sooner. I guess I just want to get the most out of my ignition to go with everything else. Thanks guys for your input and experience appreciate it.
|02-13-2010 06:37 AM|
|ericnova72||I feel that on a street engine that is running well with an HEI you will not even notice a difference in how the vehicle performs or the mileage it gets, I've done it and noticed very little from it. About all I could tell is the plugs stay cleaner if you are trying to run a too cold plug instead of the correct plug. If you were switching from points or didn't have an ignition at all and were buying from scratch I would say get a CD ignition. In your case I would find a better place to spend the money, the HEI is quite durable and fool proof, and if you are not suffereing from a miss at high rpm you are fine.|
|02-13-2010 12:12 AM|
|sqzbox||I think that if you drop the question mark on your first question, you have your answer!|
|02-12-2010 08:36 PM|
|richard stewart 3rd||
The CDI system was pioneered by Tesla you know the AC guy
who saved us from Edison's DC night mare, anyway the system is a good one using multiple sparks at lower rpm's for a complete burn, & the short duration of the spark is good for higher rpm's, the short duration of the spark & the nearly instant recovery is what allows the mutable sparks at lower rpm's causing easer starts, a little more power, & a little better gas mileage through complete combustion.
PS As to weather anyone here uses one I would guess over half, I have two, a AL6 & a 7AL2, the 6 is on a stocker the 7 is for the worked engine
|02-12-2010 07:10 PM|
Can using a msd streetfire cdi ignition be helpfull?
Hello guys I am looking this spring to do some more upgrades to my 96 chevy s10. I currently have a 350 sbc carbureted motor in it now and I am using a high performance aftermarket large cap GM HEI distributor right now.
If getting a msd streetfire cdi ignition will I really benefit with better cold starts and better combustion and get a slight increase in fuel mileage and a better overall increase in ignition efficency?
Also can my hei work fine with it for long term with no issues to worry about? I know I can hook one up pretty easy after looking at the instructions but I don't know much about CDI type boxes. Anyone actually using one.