After laughing at a mate trying to start and manouvre whilst cold his latest purchase into his workshop i've agreed to try and sort the mapping out for him.

The starting and warmup enrichments shouldn't be too hard to fix but never having mapped a supercharged car before i've had to have a little think about the main maps.

The super charger on the car is an Eaton M90 displacement type rather than the centrafugal rotrex type. My question is, being a displacement type charger will the engine have a linear relationship engine speed, throttle angle and fuel requirement? I'm thinking it will do, am i right??

If so should i map using alpha n rather than the speed density algorithm that i would usually use for the main tables on a forced induction engine?

Cheers,

Doug.

 

I'd stick a MAF on it

 

MAF....

Its linear - but when you snap the throttle closed funny thingd happen.

 

Ha Ha. Not an option as i don't want to faf about.

 

I have mapped a couple with vortec superchargers, 800hp and 880ftlb and the other was around 1500hp not dyno'd only mapped on drag strip,
Mapped the same way as a turbo.

Mark

 

Either method is fine

 

Shouldn't be a problem as i'm not too fussed what the fuelling does when the throttle closes.

 

Vortec chargers are centrifugal aren't they? This means the relationship between air movement and rpm/throttle angle won't be linear, just like a turbo. So you are right and thats what i'd do.

The problem is this is a displacement type Eaton (off a Aston Martin apparently).

 

But which ways best!

 

What engine and what application?

 

most if not all cars use map or maf and not just throttle pos....

 

2.7 M20 BMW engine, E30, Eatom M90 supercharger. On megasquirt.

 

Up for the day timers. Stu, chip?

 

Sorry to jump thread, but any pictures Doug??

 

Doug, Ive not mapped a displacement chargered car myself, so would only be able to offer you theories and opinions (which you already have) not facts and experience.

 

No, but its nothing special to look at though and the Sc installation looks a bit ropey.

I'm gonna do a leak test on the inlet side as i'm pretty sure some of the fabricated parts will be leaking.

 

Oh well. I'll just give it a go how the currant map is set up. Don't want to get too involved as i feel it may be a bit of a problem pit and i'm short on time these days.

 

Bottom line is, Im sure you can make it a LOT better than it is now by the sounds of it

 

I mapped an XR3i using a sprintex surpercharger many years ago.

I use a MAP sensor in the inlet manifold for load sensing which worked fine.

However, the TPS enrichment parameters neede extra work due to the pipe lengths and delays in the air getting through the charger when the throttle was snapped open.
This lead to too much fuel initially !!!

As for when the throttle snaps shut, that isnt a problem as you just set a fuel cut off on TPS as normal