Converting to a crank triggered ignition
08-08-2002, 08:35 AM
#1
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Thread Starter
Join Date: Jan 2002
Location: Houston, TX
Posts: 442
Converting to a crank triggered ignition
Does anybody have details about how to convert from an opti to an MSD type crank triggered setup? What's all involved, would it work on the stock computer, etc etc?
Thanks
Chuck
------------------
97 SS #1384
http://www.barncandles.com/camaro/Chucks.htm
Custom true dual exhaust http://y42.photos.yahoo.com/chucks97ss
Thanks
Chuck
------------------
97 SS #1384
http://www.barncandles.com/camaro/Chucks.htm
Custom true dual exhaust http://y42.photos.yahoo.com/chucks97ss
08-08-2002, 09:39 AM
#2
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,642
You need to read this thread... it was at the bottom of this page when you posted:
http://web.camaross.com/bb/Forum30/HTML/001074.html
In a nutshell.... sequential injection requires both a crank position (crank trigger) and a cam position sensor. Without the cam position, the PCM has no way of knowing which crank rev of the 4-stroke cycle each piston is on. The Opti provides the cam position, and a "pseudo" crank position signal. The stock PCM requires the cam position (low res) signal, or the fuel system is shut down.
So... you need to have a crank trigger and a cam position sensor to operate an aftermarket computer driven ignition timing system, or even the stock PCM in sequential fire mode. MSD has their new CPC system that uses a sensor in what is essentially a conventional distributor drive shaft. If you read the thread, you will find pics of a cam position sensor installed in an LT1 timing cover. While these systems can produce the required cam and crank position signals that all aftermarket systems require, the signals are not compatible with the high and low resolution signals that the stock PCM is looking for from the Opti.
Electromotive tried to get around this with the "Opti-Eliminator/SDI" which use a 60-tooth crank wheel to feed a chip that synthesized the high and low res Opti pulses, and kept the stock PCM happy. Unfortunately, because is relied only on a crank signal, one-half of the time the synthesized pulse signal was 180-deg out of phase and the injectors were firing at the wrong time.
A few of us are using only the optical signals from the Opti to drive aftermarket computers, and then using 8 LS1 coils. Curt uses the optical signals instead of the "Opti-Eliminator", but then uses the E'motive lost spark coil packs for ignition.
Read the thread.... someone is supposed to be coming up with a $400 solution to the problem.
------------------
Fred
94 Formula A3+1: 381/TH400+OD/N2O
Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year
http://web.camaross.com/bb/Forum30/HTML/001074.html
In a nutshell.... sequential injection requires both a crank position (crank trigger) and a cam position sensor. Without the cam position, the PCM has no way of knowing which crank rev of the 4-stroke cycle each piston is on. The Opti provides the cam position, and a "pseudo" crank position signal. The stock PCM requires the cam position (low res) signal, or the fuel system is shut down.
So... you need to have a crank trigger and a cam position sensor to operate an aftermarket computer driven ignition timing system, or even the stock PCM in sequential fire mode. MSD has their new CPC system that uses a sensor in what is essentially a conventional distributor drive shaft. If you read the thread, you will find pics of a cam position sensor installed in an LT1 timing cover. While these systems can produce the required cam and crank position signals that all aftermarket systems require, the signals are not compatible with the high and low resolution signals that the stock PCM is looking for from the Opti.
Electromotive tried to get around this with the "Opti-Eliminator/SDI" which use a 60-tooth crank wheel to feed a chip that synthesized the high and low res Opti pulses, and kept the stock PCM happy. Unfortunately, because is relied only on a crank signal, one-half of the time the synthesized pulse signal was 180-deg out of phase and the injectors were firing at the wrong time.
A few of us are using only the optical signals from the Opti to drive aftermarket computers, and then using 8 LS1 coils. Curt uses the optical signals instead of the "Opti-Eliminator", but then uses the E'motive lost spark coil packs for ignition.
Read the thread.... someone is supposed to be coming up with a $400 solution to the problem.
------------------
Fred
94 Formula A3+1: 381/TH400+OD/N2O
Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year
08-08-2002, 10:40 AM
#3
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Thread Starter
Join Date: Jan 2002
Location: Houston, TX
Posts: 442
Hmm ok... Well i guess maybe I'll just wait until I get a DFI or FAST. My car has a brand new opti... so it's not like I'm in a bind or anything. My main reason to be honest is to get rid of the stock LT1 timing cover. I don't even know if a regular sbc timing cover fits an LT1... but I'd like to get one of thoese covers that makes cam swaps easier... 
Thanks
Chuck
------------------
97 SS #1384
http://www.barncandles.com/camaro/Chucks.htm
Custom true dual exhaust http://y42.photos.yahoo.com/chucks97ss
Thanks
Chuck
------------------
97 SS #1384
http://www.barncandles.com/camaro/Chucks.htm
Custom true dual exhaust http://y42.photos.yahoo.com/chucks97ss
08-08-2002, 09:59 PM
#4
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Posts: n/a
Hey, I was mentioned in Fred's thread -- I'm famous now! 
A SBC timing chain cover will not fit a LT1. You're out of luck too -- nobody that I'm aware of makes a timing chain cover for this engine, much less a quick cam change cover.
If you're looking at changing the cam often, the bottom lip on the stock timing chain cover can be modified to make removing/installing it easier, but I believe it will be more prone to leak too.
[This message has been edited by Curt (pres AAMC & ZAA) (edited August 08, 2002).]
A SBC timing chain cover will not fit a LT1. You're out of luck too -- nobody that I'm aware of makes a timing chain cover for this engine, much less a quick cam change cover.
If you're looking at changing the cam often, the bottom lip on the stock timing chain cover can be modified to make removing/installing it easier, but I believe it will be more prone to leak too.
[This message has been edited by Curt (pres AAMC & ZAA) (edited August 08, 2002).]
08-09-2002, 11:24 AM
#5
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Join Date: Feb 2002
Location: Hagerstown, MD
Posts: 8
<font face="Verdana, Arial" size="2">Originally posted by Curt (pres AAMC & ZAA):
Hey, I was mentioned in Fred's thread -- I'm famous now!
A SBC timing chain cover will not fit a LT1. You're out of luck too -- nobody that I'm aware of makes a timing chain cover for this engine, much less a quick cam change cover.
If you're looking at changing the cam often, the bottom lip on the stock timing chain cover can be modified to make removing/installing it easier, but I believe it will be more prone to leak too.
[This message has been edited by Curt (pres AAMC & ZAA) (edited August 08, 2002).]</font>
Hey, I was mentioned in Fred's thread -- I'm famous now!
A SBC timing chain cover will not fit a LT1. You're out of luck too -- nobody that I'm aware of makes a timing chain cover for this engine, much less a quick cam change cover.
If you're looking at changing the cam often, the bottom lip on the stock timing chain cover can be modified to make removing/installing it easier, but I believe it will be more prone to leak too.
[This message has been edited by Curt (pres AAMC & ZAA) (edited August 08, 2002).]</font>
08-09-2002, 01:10 PM
#6
Registered User
Thread Starter
Join Date: Jan 2002
Location: Houston, TX
Posts: 442
What about a crank triggered setup on an Accel DFI gen 7? I think I'm probably going to be getting an aftermarket ecu sooner than I thought...
Timing covers... well, it's really no big deal. But if there were something, it'd make cam swaps a heck of a lot easier!
Later
Chuck
------------------
97 SS #1384
http://www.barncandles.com/camaro/Chucks.htm
Custom true dual exhaust http://y42.photos.yahoo.com/chucks97ss
Timing covers... well, it's really no big deal. But if there were something, it'd make cam swaps a heck of a lot easier!
Later
Chuck
------------------
97 SS #1384
http://www.barncandles.com/camaro/Chucks.htm
Custom true dual exhaust http://y42.photos.yahoo.com/chucks97ss
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