Attention ESM and others contemplating 3 BAR MAPs

[GeoffSmith]

Found this link to a home-built MAP compensator. Amazingly simple in theory: replace the ECU's standard 5V supply to the MAP with an adjustable regulated supply. Decreasing the initial supply voltage creates a corresponding decrease in MAP output voltage, causing the computer to operate in a leaner part of the MAP table. Of course, there may also be lower and upper limits programmed into the tables that ignore manifold pressures below a certain level but we'll have to rely on Alan to ferret this out of the code.

I don't think it will do a lot other than allow you to make it look like a 2 bar sensor if you supply it with 7.5V - from what I have seen of the ECU input stages, they will only measure from 0-5V, so it will have to be done by software scaling factors. I did have a look at the disassembled code a few years ago (Motorola 6800 but I used to prefer Intel 8080 - wonder what became of that architecture) when I was trying to work out what the unknown flags were for but I'm sure Alan has a fair idea where they reside. If not, I'll try and find the disassembled listing.

[tigerdog]

I agree with the idea of software scaling as the best solution. Still, I would have expected a small downward adjustment of input voltage might be enough to compensate for the slight overfueling induced by the 550cc injectors at least up to 1.3 Bar (or so) boost. Obviously it just messes things up as you approach 2 Bar boost. I guess I need to think about it some more.

[tigerdog]

from the "who has" thread:

I'd be in to. Like Monty I haven't fitted the bigger Turbo yet (in fact I haven't bought a bigger turbo yet) and would go with the consensus, I'm looking for 250-270 BHP (flywheel)

I don't know if anyone has hard evidence as to how much boost is required to reach a given horsepower level. In reviewing older threads, I found
Costas/Sh4rk: 1.2 Bar / 17.4PSI = 290HP w/o Nitrous (clicky)
Houdini: 1.1 Bar / 16PSI = 246HP with Haltech plus tuning - never did post dyno info with stock chip+3Bar+550
LGM: 15 PSI = ? HP. Marie simply quantified it as "enough" in the thread on Ekapol's 2560 upgrade
Tony: 270 BHP @ 1.25 bar (according to his signature)

Better question is, how much boost is reasonable given known durability of head gaskets and stock pistons? If CramburyRS is around, maybe he can point us to wisdom from the Isuzu forums. Again, though, the number that I keep seeing is 18-18.5 PSI / 1.27-1.3 Bar. Maybe Alan could make us up a V5 switchable chip with an 1.27 Bar cutout and selectable boost levels up to 1.25 Bar. I'd vote for including a "valet" setting that keeps the BSV closed and limits boost to warm-up levels, stock boost, then 1 Bar, 1.1, 1.2 and 1.25. levels. Discuss.

[racerstev]

My old drag car was reliable to around 375hp, above that the head gasket started to give problems.
The engine made right around 500hp at it's peak, but that was with a head gasket every 5 or 6 pass's.

The MLS gasket should address that issue though. Tuned right the stock pistons will hold plenty of power,
they are forged.

You guys really should look into the AEM FIC, it allows you to keep the stock knock sensor and tune and run
larger injectors. It also allows you to pull timing to keep knock at bay.

It has a wideband input to allow you to tune, data logging, narrow band output to the stock computer,
and a adjustable map output.

It's one of those inbetween systems between full standalone and a piggy back. Great for modest power upgrades.

[tigerdog]

My old drag car was reliable to around 375hp, above that the head gasket started to give problems.

What level of boost were you running to generate this power and were there any changes to the engine internals to accommodate?

You guys really should look into the AEM FIC... Great for modest power upgrades.

Another good alternative. I think the idea of this thread is to come up with a simple, reliable and useable chip upgrade for the stock computer that can be installed and run with a minimum of changes to engine and electronics. At least here in California, the less obvious the mod, the better.

[racerstev]

375 was with a garret 50 trim running almost 30psi. The inside of the engine was stock besides upgraded valve springs
and 1.8 liter cams. It was on a Haltech standalone running no more then 18 degrees of timing under high boost.

The car later went to a Turbonectics T66, 30PSI gave me around 425ish hp on that setup. Agein with stock internals and
a 9000rpm redline. With the 75shot of nitrous the engine made around 500.

The problem I see with a chip upgrade is how you can't tune it, it is what it is. With the power you want to run it would be
wise to tune the injecton and timing to your engine.