Educate me on valves/springs

[digger]

Not sure if this is to be believed but this may be OEM specs?

http://www.catcams.com/products/camshafts/datasheet.aspx?ENGINE_id=302&CAMSETUP_id=1497&Language=english

[mrgizmo04]

Digging up an old thread.

Does anyone have the specs for stock BMW valve springs? I've searched to no avail.

Feff

Don't know if info you need is there, but torque spec pdf has a page dedicated to OE valves around middle of the doc, like page 40 or so. Someone also added piston and crank pages there around same page number.

Sent from my SM-G950U using Tapatalk

[Feffman]

Digging up an old thread.

Does anyone have the specs for stock BMW valve springs? I've searched to no avail.

Seat Pressure (41mm)

Open Pressure (31mm)

Rate Per Inch (lbs)

Coil Bind (mm)

Max Net Lift (mm)

Feff

[digger]

Did it state what octane fuel they were running? I'd assume 93 octane...

Not sure but I would assume so

[duracellttu]

no i found those on another forum

Did it state what octane fuel they were running? I'd assume 93 octane...

[digger]

My dyno runs are a little low because I’m stuck using 91 octane. I will be able to squeeze more out of it on 93 octane when I move from California some day.

Are these your dyno runs above?

no i found those on another forum

[duracellttu]

the numbers seem a little low compared to other dynojets i recall seeing on the old site but might be thinking of the "other" inflated dyno. the power seems to plateau a bit early 7600rpm for a stock bottom end, ported head with cams and FBO

edit: maybe not

My dyno runs are a little low because I’m stuck using 91 octane. I will be able to squeeze more out of it on 93 octane when I move from California some day.

Are these your dyno runs above?

[digger]

Most people aren’t turning enough rpm or using radical enough cams to warrant Ti valves. It’s hardly a motorcycle engine

[Feffman]

.... Any experience with aftermarket valves? In the scheme of things, an extra grand on the CSL exhaust valves isn't a big deal while I'm in there. Where I'm totally lost is the specs on aftermarket valves. For stock size, are they just made to exact OE dimensions and it's just all about weight and material? ...

I spent some time researching titanium valves (stupid expensive) only to realize they aren't legal in my class. Looks like stock size stainless steel for intakes and iconel for exhaust with single groove locks. Whole host of options nitriding, ceramic face caoting, etc. to decide on as well.

Feff

[digger]

For those interested, here are my dyno runs throughout my ownership. I recently worked with Paul to tune my car after having Lang do a CSL airbox conversion, Lang Stage 2.5 head and Schrick 280/288 cams. I had a few different live dyno sessions with Paul to refine the tune and the green plot was the best run during the last session. If somebody wants to throw up a dyno run with their 280/272 setup and similar supporting mods that would be a good starting point to compare. Below is a summary of the modes in each of the runs. Keep in mind these runs were all using 91 octane.

Blue - "Baseline"

• aFe Stage 2 intake
• Borla v2 midpipe and mufflers
• TMS underpower pullies
• Electric Fan Conversion
• Stock tune (91 Octane)

Red - "Cat-less Headers"

• aFe Stage 2 intake
• AP V2 headers
• CPI euro section 1 w/ resonators
• Stock sec 2
• Stock Borla Mufflers
• TMS underpower pullies
• Electric Fan Conversion
• Evolve Tune (91 Octane)

Green - "CSL setup"

• CSL Airbox (OEM trumpets)
• Lang Stage 2.5 head (Super Tech OE sized valves and springs) / stock bottom end (still had 99% compression)
• Schrick 288/280 cams w/ DLC followers
• Ported exhaust on head
• SS V1 stepped headers
• SS catted sec 1
• SS twin pipe resonated sec 2
• SS race mufflers
• TMS underpower pullies
• Electric Fan Conversion
• Paul Claudes Custom Tune (91 Octane)

the numbers seem a little low compared to other dynojets i recall seeing on the old site but might be thinking of the "other" inflated dyno. the power seems to plateau a bit early 7600rpm for a stock bottom end, ported head with cams and FBO

edit: maybe not

[jbfrancis3]

For those interested, here are my dyno runs throughout my ownership. I recently worked with Paul to tune my car after having Lang do a CSL airbox conversion, Lang Stage 2.5 head and Schrick 280/288 cams. I had a few different live dyno sessions with Paul to refine the tune and the green plot was the best run during the last session. If somebody wants to throw up a dyno run with their 280/272 setup and similar supporting mods that would be a good starting point to compare. Below is a summary of the modes in each of the runs. Keep in mind these runs were all using 91 octane.

duracellttu I don't think many of us with have a good comp to your setup. However, I think your plot deserves a thread of its own to call attention to the work PC has done with those cams. Congrats on 400hp! That flat-ish torque line is impressive and deserves more exploration. It would be interesting to pick apart how much of it is due the headwork.

[bjz!]

i recall the 288/280 cams that Paul posted of his own car showed gains right across the board not sure it was only a cam sway or other things thrown into the mix. Another dyno of 280/272 cams totally different showed lesser gains down low.

The problem here, always waas the tune. Now this is pretty much sorted out.

[digger]

Good memory, that's right. I lost you in the at the underlined part; cannot tell which one and which aspect you are saying is worth / not worth 😵

i recall the 288/280 cams that Paul posted of his own car showed gains right across the board not sure it was only a cam sway or other things thrown into the mix. Another dyno of 280/272 cams totally different showed lesser gains down low.

[duracellttu]

For those interested, here are my dyno runs throughout my ownership. I recently worked with Paul to tune my car after having Lang do a CSL airbox conversion, Lang Stage 2.5 head and Schrick 280/288 cams. I had a few different live dyno sessions with Paul to refine the tune and the green plot was the best run during the last session. If somebody wants to throw up a dyno run with their 280/272 setup and similar supporting mods that would be a good starting point to compare. Below is a summary of the modes in each of the runs. Keep in mind these runs were all using 91 octane.

Blue - "Baseline"

• aFe Stage 2 intake
• Borla v2 midpipe and mufflers
• TMS underpower pullies
• Electric Fan Conversion
• Stock tune (91 Octane)

Red - "Cat-less Headers"

• aFe Stage 2 intake
• AP V2 headers
• CPI euro section 1 w/ resonators
• Stock sec 2
• Stock Borla Mufflers
• TMS underpower pullies
• Electric Fan Conversion
• Evolve Tune (91 Octane)

Green - "CSL setup"

• CSL Airbox (OEM trumpets)
• Lang Stage 2.5 head (Super Tech OE sized valves and springs) / stock bottom end (still had 99% compression)
• Schrick 288/280 cams w/ DLC followers
• Ported exhaust on head
• SS V1 stepped headers
• SS catted sec 1
• SS twin pipe resonated sec 2
• SS race mufflers
• TMS underpower pullies
• Electric Fan Conversion
• Paul Claudes Custom Tune (91 Octane)

[jbfrancis3]

the one i saw from PC had exhaust mods and it was fairly clear that those changes were influencing making it impossible to draw much in the way of conclusions. So i still maintain no one has posted a comparison of cams and cams alone on these forums with same engine so a lot of peoples beliefs may very well be unfounded.
Yet whenever i've seen gains from stock cams to 280/272 or stock to 288/280 the respective deltas on different setups don't support the 280/272 having all the top end without the bottom end losses that the 288 have.

Good memory, that's right. I lost you in the at the underlined part; cannot tell which one and which aspect you are saying is worth / not worth 😵