Dyno plot of racecar
03-25-2006, 09:34 PM
#4
Nordschleife Master
It is going to depend on a number of factors. You use fuel to manage the heat in the engine. You haven't mentioned whether N/A or boosted, nor what the stock compression ratio is. Unless you are doing something that is putting excessive cylinder pressures, those AFRs are likely too low. Judging by the graph, I'm going to assume N/A and at a stock compression of about 10.0:1. I would be aiming for 13.0-13.2 as a starting point. Since it really doesn't appear to have a high VE%, I would think that you can probably run up to 13.5:1, especially if it is a 4 valve pent roof cylinder head. Again, there are a lot of factors and you haven't provided many detalis, and so I've made a lot of assumptions here.
FWIW, if it were a 2.0l Honda, I regularly run them at 13.5:1 under full power. They are an extremely efficient engine with good cooling.
FWIW, if it were a 2.0l Honda, I regularly run them at 13.5:1 under full power. They are an extremely efficient engine with good cooling.
03-26-2006, 12:57 AM
#5
Race Car
Thread Starter
Originally Posted by OriginalSterm
Hey now! 2L, 4 cylinder, naturally aspirated, stock compression, 16 year old car! But yeah...
03-26-2006, 08:25 AM
#6
Nordschleife Master
The DSM engines at stock compression N/A will be fine in the 13.3:1 range on street fuel under full power. At cruise you can lean them out to 14.7:1-15.0:1.
03-26-2006, 10:44 AM
#7
Race Car
Thread Starter
fuel pressure is set about 10 psi over stock, if i pull this back to stock or close to stock will that bump me back up to the low 13 range? it has the stock computer and is running an O2 sensor with stock injectors. or did these things run rich from the factory?
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03-26-2006, 11:31 AM
#8
Nordschleife Master
What exactly are you trying to do? It sounds like the engine is stock, so leave it stock, the way it came. Adding fuel isn't going to give you additional power over what it came with stock.
03-26-2006, 11:47 AM
#9
Race Car
Thread Starter
i didn't add fuel. this is how i got the car a year ago. the previous owners, for whatever reason, seem to have bumped the fuel pressure. i'm just wondering if fuel pressure alone will get me into the a/f range that i need to be in. and if that range is any different than that of a stock DSM.
03-27-2006, 12:09 PM
#10
Burning Brakes
Fat fat fat fat fat fat fat fat fat.
That baby is running fat. Where was the O2 sensor in the system ? Jammed up the tailpipe, or within ~8-12" of the collector ?
I would think that Larry would have recommended leaning it out a bit.
That baby is running fat. Where was the O2 sensor in the system ? Jammed up the tailpipe, or within ~8-12" of the collector ?
I would think that Larry would have recommended leaning it out a bit.
03-27-2006, 01:29 PM
#11
Race Car
Thread Starter
Larry and the other kid said it was probably fine to be that rich. They said better than being lean...
The stock O2 is right at the collector, the wideband for the dyno is stuffed in the exhaust right at the end (under the driver's seat roughly).
The stock O2 is right at the collector, the wideband for the dyno is stuffed in the exhaust right at the end (under the driver's seat roughly).
