IGNITION RETARD UNDER BOOST

[jl222]

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.

    Did you try leaning the motor with water injection? My next computer will be able to post pictures. there's a chart from Ricardo's book showing water injection. He started lean on fuel increased boost to detonation then added fuel and boost on up to no more power could be made with increased fuel then added water injection and increased power a bunch to limit of dyno but he also leaned the motor back to were he started.

     JL222

[McRat]

Here's my guess (and only a guess):

Water creates thinner air, so when the water sprays, you need to advance the timing to compensate for the lower effective oxygen density.

I personally can't advance my timing due to something called bursting, but that's a different subject.

[wilcox garage]

Honestly we did not have enough time to give the water injection enough attention. This was a big learning curve for me my crew (good friend and brother) and the dyno operator. Non of us had messed with a blow through carb set up, I just spent a lot of money on the blower, carb, engine etc. to get greedy on the dyno three weeks before speed week. We spent two days on the dyno and found 300 hp from start to finish with a very safe tune up and did not hurt anything we were far from leaning the engine out, overall  I was very happy.  I would be interested to see those sheets ,no one I know runs water injection and I would like to give it more attention on the dyno now that we have a good base tune up and timing curve.                                                                                                                                                                                                                       thanks Mark

[dieselgeek]

Well, we did the dyno session last weekend and it went good.  We achieved our goals, which were to carry power all the way to redline - the old turbo setup was too restrictive on the exhaust and started causing too much backpressure, and power loss, above 5900rpm or so.


Dynoroom, what we did with the megasquirt was the exact same way we were running his MSD ignition.  We have the engine running 36 degrees advance, even at light load, and at idle.  Then as boost comes on, we ramp downwards to a total timing of 24 degrees, where it seemed happiest on the dyno.  (power increase was falling off with additional timing).   Really, the *only* benefit we got from controllng timing with the megasquirt was the fact that we can (1) datalog our advance, (2) have better mapping based on boost if we need to "turn it up" on the salt (the 6BTM is a bit of a guess when doing this), and (3) best benefit of all was to be able to control timing during cranking.  When the engine was warm, it would kick back on the starter when running 36 degrees on the MSD 6BTM setup.  Now we are able to run a 10-15 degree advance when cranking, and it doesn't kick back on us at idle.


I'm not really treating this one like a street engine, with lots of advance under decel, etc.  So basically I'm running it just like you would suggest.  I know better than to disagree with you    and besides, who worries about the deceleration tune on the salt flats?? 


To the guy who suggested correct rotor phasing.  This is great advice that a lot of people miss.   We made sure that the rotor was directly underneath the correct spark tower when the engine is at it's peak power timing, or 24 degrees BTDC.  That way, at peak spark energy demand, we have the shortest possible gap for the spark to cross between the rotor and the cap/tower.  Thanks for the good advice!

Some other interesting stuff we found.   Corrosion - BAD - underneath the injector clips.  We had one cylinder misfiring on the first pull and as we poked around, we caught the corrosion...  cleaned them all up, and she was hitting on all 8 just like always. 

This d*mn salt is something else, unbelievable corrosion in such a short amount of time.  It makes midwest winter roadsalt seem like Florida.


Thanks guys,
-Scott
I will post up a video soon.

[Dynoroom]

Good post Scott with good solid information too. I'll be watching Gary's car this speedweek to see how it performs.
Good Luck to you guys.

Scott will you be at Speedweek?

[dieselgeek]

Good post Scott with good solid information too. I'll be watching Gary's car this speedweek to see how it performs.
Good Luck to you guys.

Scott will you be at Speedweek?

I am going to try.  The planets seem to be lining up that way...  I *really* want to be there if Gary gets his red hat.  We've worked so hard for it.  It's been a LOT of fun and a huge learning experience...   and we still need to meet in person,

-scott

[SPARKY]

Scott, I will not forget yours and Pauls help on getting me going year before last,

THANKS again Sparky

[theazoldcrow]

Sparky!  I'm in Mammoth, Az. and I need to find someone who does louvers...you know of anybody or shop with a louver press???  (differant sizes will be needed) Either in the Tucson or Phoenix area.   Thanks!   Crow

[goldleaf]

Crow,

I have had louvers done for my Roadster by Gary Criss in Tucson.  His number is 520.465.0726.  I was very pleased with his workmanship. 

Francis

[theazoldcrow]

    Goldleaf!  Tanks!!!!  Just started the 39 Chevy p/u project and neede that info for the budget.... Thanks again!   Crow