IGNITION RETARD UNDER BOOST

[GH]

What do some of you guys do with ignition retard when the engine is under boost? I have a big block Chevrolet, turbocharged and EFI. We have been starting with 36 degrees and retarding to 26 degrees. This is at 15 psi boost, seems to work good but we are going to play around with it this winter on the chassis dyno. We have been using the MSD-6BTM but no we are going to control the ignition with the Megasquirt.

[fredvance]

Are you loggin EGT?

[GH]

I use one of those cheap EGT units with the 9V battery, the battery went south last August. It reads on the left bank only.

[Dynoroom]

Gary, JMO but when you have a large displacement engine that's supercharged on the salt I don't advance the timing. I have enough trouble getting hooked up so I don't need/want the power down low. I run most of my stuff with very little if any timing curve. I know Scott will disagree but that's how I do it. Total timing on my turbo engines is all I run except some of the smaller engines < 300". Then I hove found it advantages to advance the timing to help the car accelerate off the push truck.

Now if you're going to ramp the boost with the M/S there might be some advantage to adding timing under lower boost levels but I doubt it. But that's why we have these tools, to try our ideas.

Good Luck this year.

[Richard Thomason]

Small engines with big boost can make for radical changes in horsepower when the boost comes in. Ignition retard is a good way of overcoming that. Gee, I thought we were the only ones that figured that out. Right.

[oz]

Are you wanting to retard the Ignition for reduced risk of Detonation if so have you thought of water injection i thought about it for a nitrous set up and it may be worthwhile looking into,also gives you a nice cool charge,
I could be barking up the wrong tree but its a thought.

Oz

This was one of the answers i got it is in the Water/Methanol section

Well getting back to the original topic, water or alki injection does make wonders for detonation suppresion, cooling and octane boosting on forced induction engines. Now water/alki and nitrous hasnt been as widely researched and the people that have arent talking about it, i've talked to Rodney from Alcohol Injections Systems about it and this is part of what he answered me:
"Hi Rudy,
First of all let me say, running water methanol injection with nitrous is perfectly fine. We actually sell many systems to strictly nitrous users as it offers the benefit of increased octane while stabilizing the combustion process.  This allows users to then run much less ignition retard while adding some extra safety to the motor at the same time."
The cons i see with running this kind of set up in N/A nitroused engine & water/alki injection would be tunning as it would run very rich since these systems are normally setted up for boost not nitrous and would need extensive tunning and scanning logging tools to get the proper A/F ratio when on the gas.
Try checking out all the alcohol/water injection at the following link:   http://www.alcoholinjectionsystems.com/Tech-Articles/t7/articles.html

Rudy.
 
 
  Logged
 

[GH]

Mike, I drive off from the start line, so I think I need the advanced timing. I took your advise last year and short shifted as soon as the rear tires came loose. Was able to run 100% throttle for 35 seconds in 5 gear about 2 miles.

[McRat]

If I understand the rules correctly, the instant you use anything but water from a sealed container, you switch over to Fuel engine classes, and then you should probably just switch completely to methanol.

IIRC, there are two reasons you retard timing under boost in a gas engine.  One is to supress detonation, but the other is that boosted air/fuel mixture burns quicker, so peak HP will occur with less timing under boost than it will NA.   

[McRat]

Small engines with big boost can make for radical changes in horsepower when the boost comes in. Ignition retard is a good way of overcoming that. Gee, I thought we were the only ones that figured that out. Right.

I welded the advance weights shut on a bike I turbocharged decades ago so it had fixed timing (points/coil).  The boost came on all at once with a vengence. 

[Sumner]

If I understand the rules correctly, the instant you use anything but water from a sealed container, you switch over to Fuel engine classes, and then you should probably just switch completely to methanol......

That is correct, but if you want to use water it is not a big deal.  You just go to the fuel truck with your water container for the water injection in the car empty.  Produce some bottled water.  They will ask you to drink some and it you can still walk a straight line you pour it in and they seal it.  Same if you are lucky enough to go to impound.

If you can make more than a run with your sealed gas tank on the car it would be a good idea to make sure you hold enough water in its sealed container so that you don't have to go back and get in line and add more and have it sealed.

If you are running fuel anyway then put whatever you want in the water.

We run Snow Performance water injection,

Sum

[fwillyj]

-when you are running a distributor---and electronically retard the ignition timing and/or use any other external timing trigger such as a crank trigger----you need to understand "rotor index".

-"rotor index" is simply the alignment of the rotor tip to the inner distributor cap terminals----and that alignment moved about with vacuum advance----- and with externally controlled timing triggers

-locking the distributor's mechanical advance can also affect this sometimes depending on how that gets locked out.

-It's very easy to have the rotor index alignment to the inner cap terminals move so far that the rotor is nearly 1/2 way over toward one of the next two adjacent terminals---and this is NOT GOOD.

-best way to verify what you have is to either get a clear cap to use for testing purposes----or cut a section out of a distributor cap to use for a test cap----cut this window about 1-1/2" long and maybe 3/4" wide----to where you can see well inside the distributor.

-then you can connect a timing light to the terminal nearest that window----see what you currently have for rotor index----and then watch what happens when you activate the boost retard switch.

-this all can be somewhat of a problem to understand how to fix----unless you have access to a distributor machine where you can install all your ignition components and test.

-if you've never been in there looking at rotor index it's well worth looking into.

[McRat]

If I understand the rules correctly, the instant you use anything but water from a sealed container, you switch over to Fuel engine classes, and then you should probably just switch completely to methanol......

That is correct, but if you want to use water it is not a big deal.  You just go to the fuel truck with your water container for the water injection in the car empty.  Produce some bottled water.  They will ask you to drink some and it you can still walk a straight line you pour it in and they seal it.  Same if you are lucky enough to go to impound.

If you can make more than a run with your sealed gas tank on the car it would be a good idea to make sure you hold enough water in its sealed container so that you don't have to go back and get in line and add more and have it sealed.

If you are running fuel anyway then put whatever you want in the water.

We run Snow Performance water injection,

Sum

I run the Snow system also to try and save the turbine.  A diesel doesn't detonate, but high EGT's will damage the turbocharger turbine wheel.  At $2500 a pop (not rebuildable) water is cheap insurance.  Unlike the advertising brochures say, we did not gain 1 rwhp with water.  But it did lower EGT's from 1800°F to 1650°F. 

At Bonneville, they sealed our water tank, but at El Mirage they didn't.

[jl222]

What do some of you guys do with ignition retard when the engine is under boost? I have a big block Chevrolet, turbocharged and EFI. We have been starting with 36 degrees and retarding to 26 degrees. This is at 15 psi boost, seems to work good but we are going to play around with it this winter on the chassis dyno. We have been using the MSD-6BTM but no we are going to control the ignition with the Megasquirt.

 Gary you need to double your boost

    JL222

[GH]

John, I sent the turbos off and had them modified, just got it started yesterday. They clipped the impeller on the turbine side for less exhaust restriction and changed the compressor impeller and housing for more boost.

[wilcox garage]

With our d blown engine we spent most of our dyno time on figuring a timing curve . We run a MSD 7al-2 with the boost retard for our application we started out safe and started adding timing until we made a number we were happy with. We also ran a water injection kit from the Supercharger Store wile running  ERC gasoline , the water ended up costing us considerable H.P. We even tried turning the water injection on at different boost settings but it cost us power every time. It may be a good thing on pump gas or at higher timing but I was afraid to put in too much timing at 19 LBS  of boost.