Detonation and staggered ignition timing

Any body have any experience monitoring detonation while tuning individual cylinder timing?

Which cylinders tend to detonate first in the LT1? Is this different than a sbc?

What is the timing difference between these cylinders?

Additionally, if individual timing control is not possible, what amount of power, if any, is lost just retarding the overall timing to bring the wayward cylinders back inline?

Good question.... I'll throw some thoughts at you later.

I would imagine that the LT1 has a bigger difference in good and bad cylinders in this reguard than a SBC, but basically the same would be good and bad.

Bret

I would imagine that the LT1 has a bigger difference in good and bad cylinders in this reguard than a SBC...
Bret

Because of the intake design?

Because of the intake design?

...probley more due to the valve spacing relative to the bore centers. It's just a specuation on my part.

I'll get back to this after I work out tonight hopefully....

Yeah the port layout plays into this, but more like the exhaust port layout.

Bret

Comon problem on SBC/LT1's is the center two exhaust ports.... They cause really hot coolant temps between them. So the exhaust valve side of the chambers in the center two cylinders is really hot, and can cause hot spots there so those holes might want less ignition lead.

I've seen some interesting coolant setups on SBC's..... (BTW Fred or Ken this would be good to merge with the reverse cooled SBC thread here)

Here is a good pictures of a reverse cooled Chevy....

http://popularhotrodding.com/enginemasters/challenge/2004/0403phr_emc_33_z.jpg

I've seen a few like that setup.

There is also another picture I have on my computer which if someone would host would be cool. It's the #2 motor in the 2004 Engine Masters that DEI helped with. Instead of plumbing coolant thru the heads they plub it into the block in between the middle two cylinder bores half way up the block. They pushed it thru there and out of the cylinder heads at the ends into a water manifold. I have to think that this gives equal cooling to the cylinders.

Only real way to tell is with thermocouples all thoughout the heads.

Actually I like the plubing to the ends of each head without a coolant crossover in there and running a small line to between the center two cylinders exhaust ports from the other side of the head. The LT1 is a little difficult because the back cylinders have to be hot as well getting warmer coolant to them. I'm still figuring out how to do that well in a LT1.

The only way you really lose power in timing is when some cylinders are hotter than others and they need less to stay out of detonation. If you can prevent that and have identical cylinders then you should be golden.

Bret

I appreciate the thought and infomation about the effects of coolant temperature on individual cylinder performance.

I was thinking there might be a cylinder imbalance more along the lines of uneven air flow to the cylinders creating a difference.

Additionally, combusiton chamber final configuration depending on the tolerance stack up during machining and assembly, could cause a difference.

I'd still be interested in timing differences between cylinders to accomodate any differences reguardless of cause and the potential effects on power production and detonation.

A little more of what I know, MSD appearantly makes a device that provides up to 6 degrees of individual cylinder timing control. Stock car boys appearantly file the edges of the cap to retard individual cylinders (where electronic timing control is illegal).

Stock car boys appearantly file the edges of the cap to retard individual cylinders (where electronic timing control is illegal). :eek:

I meant to say the edges of the individual cylinder terminals under the cap.

Additionally, MSD has a unit that is encased in the distributor housing for stealth type applications.

There is also another picture I have on my computer which if someone would host would be cool.
Bret

Bret -
If you send me the picture at; ericscher-at-mac-dot-com, I'll host it for you.


(My address is written that way to avoid e-mail harvesting robots. Just convert to the proper "@" and "." symbols.)

I'll e-mail that to you later tonight I don't have it at the shop

I meant to say the edges of the individual cylinder terminals under the cap.
This ploy will do nothin' to affect or alter the timing.

yep they can just bend the reluctors in a regular setup.

Any real endurance Chevy making any kind of power has all the center water modifications done to get more water between those seats. You will lose the heat treat there on the heads pretty fast otherwise. There many ways do do it.

MSD makes a thick reluctor that allows machining it down to relocate each cylinder trigger point to be moved a few degrees either way.

Here is a good pictures of a reverse cooled Chevy....

http://popularhotrodding.com/enginemasters/challenge/2004/0403phr_emc_33_z.jpg

I've seen a few like that setup.

Huh, if I’m seeing right he’s pumping the coolant in through the 4 corners of the intake and through the normal inlet on the front of the block, unless those are blocked off. Is that right? If they were blocked off it would almost make sense to just remotely mount the pump…

The only return appears to be from in between the center 2 ports which goes straight to the thermostat housing…

There is also another picture I have on my computer which if someone would host would be cool. It's the #2 motor in the 2004 Engine Masters that DEI helped with. Instead of plumbing coolant thru the heads they plub it into the block in between the middle two cylinder bores half way up the block. They pushed it thru there and out of the cylinder heads at the ends into a water manifold. I have to think that this gives equal cooling to the cylinders.

If you haven’t found a place yet, email it to me and I’ll put it up someplace for you.

MSD makes a thick reluctor that allows machining it down to relocate each cylinder trigger point to be moved a few degrees either way.

Wire EDM is another nice way to make "odd-fire" reluctors.

Sent you Pics....

Huh, if I’m seeing right he’s pumping the coolant in through the 4 corners of the intake and through the normal inlet on the front of the block, unless those are blocked off. Is that right? If they were blocked off it would almost make sense to just remotely mount the pump…

The only return appears to be from in between the center 2 ports which goes straight to the thermostat housing…


Yep, block off plate in front of the water entrance to the block.....

In the rules of the contest you can't remotely mount the pump.

The return is from the bottom of the block to the thermostat housing on the front of the intake.

Bret

Wire EDM is another nice way to make "odd-fire" reluctors.

It’s a nice way of accomplishing a lot of stuff… I’ll be sure to get one the next time I head out to home depot…

It’s a nice way of accomplishing a lot of stuff… I’ll be sure to get one the next time I head out to home depot…

LOL here. Make that your local machine tool "big box". I like how you think.

If you need one, let me know.

Sent you Pics....

Ok, here they are… the original were enormous (something like 2k x 2K pixles), so I’m posting edited (lightened…) and shrunk (640x480) versions here, click on them and you’ll get a ½ the original size (1280x960, plenty big to see any detail) version (let’s see if I can get this to work):
http://www.midimonkey.com/~mpikas/temp/DSCN0637s.JPG (http://www.midimonkey.com/~mpikas/temp/DSCN0637m.JPG)
http://www.midimonkey.com/~mpikas/temp/DSCN0642s.JPG (http://www.midimonkey.com/~mpikas/temp/DSCN0642m.JPG)
(these will live here till I get around to cleaning, at least months, more then likely, years)

Bret, feel free to comment here.

Yep, block off plate in front of the water entrance to the block.....

In the rules of the contest you can't remotely mount the pump.

The return is from the bottom of the block to the thermostat housing on the front of the intake.

From the bottom of the block, you mean from in between the 2 center cylinders or something else?

Ok, here they are… the original were enormous (something like 2k x 2K pixles), so I’m posting edited (lightened…) and shrunk (640x480) versions here, click on them and you’ll get a ½ the original size (1280x960, plenty big to see any detail) version (let’s see if I can get this to work):

Crud, I forgot that this board doesn’t seem to allow you to see pics in the thread… Ok, the links above link to the small, 640x480 pic, if you want the bigger pic just remove the “s” right before the “.jpg”

From the bottom of the block, you mean from in between the 2 center cylinders or something else?

Actually, I just took a better look, looks like the return is actually coming from the drain hole on either side of the block where they normally install the KS...

any idea if in either one of these they have the normal water pump connectoin to the block blocked off? In this second set of pics it really looks like they have it plumbed so that the water flows bottom up like normal, but from the center up instead of from the front bottom back and then up...
Anyone have any input on if this kind of thing is worth doing?