Interesting SDS EFI results, Stock 1.8 vs. a 2.0 with a Scat C-25 cam Options

[Mark Henry]

I sold the 2.0 junkyard dog (a 2.0 I made from scrap parts) it was stock except for the C-25 Scat cam and installed my bone stock 1.8
Here’s what’s happening.

I haven’t even adjusted my values and I still have an OK reading on my narrow-band (Haltec AF 30) meter. I have a wide-band on the way from SDS, so I’ll have a direct comparison in about 1-1/2 weeks.

My duty cycles are down about 10% across the board, I get no more than 40% (WOT) duty cycle. At highway speed I’m no more than 20% DC. I’m still using the 2.0 injectors…I think I’ll swap them out for 1.7’s and see what happens.

The main interesting point is the 2.0 always lurched a bit at 1500 to 2500rpm, it was a bit of a PITA in stop and go traffic, never at normal rpms. My manifold pressure was always all over the place. I have since installed this engine in a bug with 44mm Webers and an A-1 header and it now has none of the lurching.

The stock 1.8 has no lurching at all and the manifold pressure is now rock solid! Power is down from the 2.0, but that was expected. It is just as smooth as the old L-jet except for start up, as I have no cold enrichment.

Cam choice is very important!

When I get the 2.6 done (looks like late summer now) it will have a special MassIVe cam so we’ll see how it compares in the drivability department.

Jake and I will be comparing notes to figure out the best combo’s for his and my customers.

[phantom914]

QUOTE (Mueller @ May 17 2005, 08:56 AM)

QUOTE I'm not sure where you mount you're MAP sensor, but if it is not close to the manifold (meaning a long hose), another factor in response time is whether you place the restriction close to the sensor or to the manifold Nothing wrong with a long hose as long as it is strong enough not to collapse or change shape with the changing signals. (and the diameter is small, you wouldn't want to run a 1" hose (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) ) The physical placement of the MAP sensor has no real bearing on the readings.....a hose up to several meters long can be used.

My point was that with a long hose, the placement of the restriction could be another factor. For instance, with a restriction placed near the manifold, you can end up with a slight canister effect which will slow the response due to the volume of air between the restriction and MAP sensor. Maybe. I didn't mean that the steady state response of the sensor would be affected, just the transient response.



Andrew