A day(ok,days..) at SMG dyno shop with my Harrop equipped Atom

[Heywood-Yablowme]

Loooong day. If it could go wrong...it did. Fixed the coolant pump problem,only to return to the dyno shop to be told the dyno computer is not working..   Couple of calls and an IP(?) guy shows up to fix things. A few hours later,we are up and running again.We tie Max down and start experimenting. The used ecm I had installed the trifecta tune on will not accept HPTuners...wonderful.Trifecta says the tune is not locked..but Fred can't reflash it. I am so missing carburetors at this point...Luckily,SMG has a spare ecm on the shelf. We run the Trifecta tune for giggles..holy sh1t-rich!! It pegs his A/F meter at 9-1 right after 3k rpms...made about 90hp..I knew it was very rich.   Moving on..  Fred has a Harrop 2.95 pulley tune file he loads on the donor ecm and we try a pull to 4k. Needs more fuel...but makes 255ft/lbs of torque! A few more pulls and we are up to 5k rpms and 275hp/tq. Some more fuel..some timing..At 6k rpms..we are at 296ft.lbs of torque and 316hp..corrected! with only 15 degrees of total timing..120 degree intake temps after the pull, and NO methanol ...BUT..we are out of frequency on the mass air meter. We will either have to install a bigger intake tube..OR... switch the ecm over to speed density.    I have always preferred this method of fuel injection,but did not think the GM ecm could be run or tuned in this manner. Fred says..no problem..   It will take some tuning..but he guarantees I will be smiling.  The only thing about speed density is if you make any changes to the engine,the tune cannot alter itself,it has to be retuned.Fine with me.  Tomorrow is another day....to be continued...

[silver]

cool deal

your air intake limits match what was expected hence the urging of the peanut gallery for you to replace your air intake tube
and seems your 60's were able to be tuned so it wouldn't run so rich after all huh

what a day, at least you have great progress so far that gets me excited, can't wait for arrival.

[positron]

SD tuning on P12 is not a problem. Tuners either love it or hate it. Best to be done with a real loading dyno and not a inertia dyno. It will be tuned to your car with your components and will/may not transfer to another like engine. It might be close but I wouldn't recommend sharing.

[silver]

What is the definition of sd tuning on p12

[positron]

The Cliff notes version of Speed Density tuning, on our ecu (a GM P12) doesn't use the MAF for figuring out what the airflow is. It uses a Volumetric efficiency table to know what the air is. Kinda like a spreadsheet, at so much RPM (column) and so much manifold pressure (row) use this value in your calculations to calculate how long to squirt.

Otherwise the MAF figures it out and sometimes a combination of both.

[Heywood-Yablowme]

I use a speed density based tuning system on both my Mazdaspeed (turbo) Miata and Supercharged 5.0 Mustang. I have always liked how consistent they run. I was not even aware that the GM ecm could be run on SD tables,but I am glad that it can!. I remember back in 1988 when GM came out with a Mass air meter system for the X body cars.They ran SO badly after a while,that GM came up with a fix: convert them to speed density. I could always get in one of those cars and tell which ones had been converted and which had not.

There were lots of LSJ/LNF projects going on in this shop. I'll try to remember my camera..

[DarthChicken]

The problem with speed density on our ecus is that your limited to 6800rpm for fueling.  I'm personally not sure what happns when you run off the end of the table, I'm assuming it uses the same fuel map as the map at 6800? 

[positron]

Seems to, so far it seems to get a smidge richer since VE is tailing off it should get that delta percent richer.

[quote="MadMaxAtom and company"]
There were lots of LSJ/LNF projects going on in this shop. I'll try to remember my camera..
[/quote]

Spill... prying eyes want to know..

[Hedge]

Hilarious.
I can honestly say I can understand about two words of this entire thread.

Gotta love Atoms/ cars, in general, eh. Each to their own etc 

Cheers, Hedge

[Heywood-Yablowme]

I'll ask about fuel above 6800.Thanks for the heads up! I was planning on a 7400rpm ceiling. As long as it is still OK a/f ratio wise,it should work. He will be using the maf signal to control the Methanol injection.Should be interesting..

[silver]

[quote="MadMaxAtom and company"]
I'll ask about fuel above 6800.Thanks for the heads up! I was planning on a 7400rpm ceiling. As long as it is still OK a/f ratio wise,it should work. He will be using the maf signal to control the Methanol injection.Should be interesting..
[/quote]

use the yellow wire...no seriously LMAO I just removed mine

what exactly do you want to gain from the meth.

you have the power, you have NO heatsoak, so do you want meth for safety?

[NormLarson]

Meth / water mix does two things cools and adds octane.  If he goes for a methane rich mix he can add timing and more HP

[silver]

I guess if you really want to push the stock internals...........I don't particularly want to however.

[DarthChicken]

Of course he's going for more power.  If he pops a piston, who cares?  I changed out the pistons in my car over a weekend and a few weeknights, with only the service manual;  Mark is a mechanic and does this stuff for a living. 

Hell, I didn't even hone the bores or even remove the block from the car, just put new rings on the pistons and put it back together.  Never burned a drop of oil, and never had an issue.

Push it, drive it, and if it blows up, fix it 

[silver]

yes well I think it's obvious my technical experience is limited and for the time being so is my funding.....at least the funding side is on its way to being well mended shortly   bad economy pffffttt how about growing the biz by 100% year over year 2 years going..YES please.