MyE28.com

It's not a BMW, but I thought it has relevance to some of our discussions here...

http://www.automotosports.com/cam_test.asp

Jim

Nice, it appears 264 is the way to go for a nice street cam in that motor. Anybody know what the stock mitsubishi cam duration? Just curious as a reference.

Jeremy

The problem with that test is that no cam specs other than the "advertised" duration are mentioned. It'd be illuminating to know what the duration at 0.050" lift is, what the ramps are shaped like, and what the maximum lift is. Almost all American cams are rated at both the advertised and the 0.050" lift points, and it's easy to compare two cams to see how aggressive the ramps are.

For example, if we have two "264" cams, but one has a 0.050" duration of 214 and another has a 0.050" duration of 224, we know the latter opens and closes the valves more quickly and will likely produce more power. Similarly, if two cams both have a 0.050" duration of 214, but one has an advertised duration of 264 and the second has an advertised duration of 254, the latter will have better torque and probably the same power. All of this is considering that these cams will have the same lift.

More data on the available M30 cams would be nice to have, but given the small number of choices and the likelihood that the ramps are ground the same within a given manufacturer's line, there's not much need to know more than the advertised duration.

What is the general consensus about having a company do a weld and regrind for an M30. Delta did mine, i believe it's a 270/270 w/ 11.43mm lift intake & exhaust but i'd have to dig up more info to be more specific. I'm reeeeaaal curious how it's going to behave. Intake valves are 47mm dia. stainless; exhaust are 38mm dia.

I've put the information into Dyno2000 but I don't think I've got the turbo information correct. If someone knows what I should put into the fields (Flow; Pressure Ratio; Efficiency; Boost Limit & Surge Flow), I might be able to get a better idea. THe data file with Dyno2000 isn't very good at explaining what it wants for these.

Jason

griffith - Id do a search on Reading/Understanding Turbo Compressor Maps

i understand the majority of that data, i suppose i have specific questions about what data the program wants more than anything. for example, does it want this data at maximum boost/maximum rpm or at the rpm my engine will be squarely over the island? also, does 'boost limit' indicate maximum boost the engine will be set to, or the maximum boost that the turbo can sustain relative to the rest of the data? i would assume the later, as radical changing of this data input does not radically affect the output hp/tq data.

additionally, i'm curious where the 'pressure ratio' information comes from. beyond that, i can calc the surge flow, flow, eff, etc pretty easily assuming i'm calculating that from redline. i had the pressure ratio set to 2.50 but i'm not sure that's correct. everything else i've got correct assuming 'boost limit' is the max boost for my vehicle. on some maps the 'pressure' side of the graph is simply indicated in pressure (bar) and in others it actually says pressure ratio. my data file asks for 'the ratio of compressor pressures at the island flow point (ambient vs. output)' If this is the case, and the scale on the left side of the compressor map is that data, the island goes from 1.5bar to 2.5bar.

with that said, it's showing 489hp and 366tq albiet a bit higher than i wanted to rev the car (7500rpm). i was charting it all from about 5500. should i now go back and re-input the data from the map assuming 7500rpm? problem is that lands pretty far off the island. the way i'm looking at it, if i take this data, i can be assured that (assuming the pressure ratio is correct) up to 5500rpm the dyno plot is mildly accurate. beyond that though, the dyno plot is assuming that the higher rpm's are behaving like they were on the island when they are in reality, not.

thanks for the help.

jason


[Edit by griffith on [TIME]1119714786[/TIME]]