Idle MAP vs CAM size

[samh_08]

Simple question :)

State your idle MAP pressure (PSI or kPa), and the cam setup you're using.

Maybe it'll help some of us diagnose idle tuning issues, or vaccuum leaks.

Thanks!

[joecar]

Hi Sam,

Idle MAP goes up as cam duration and overlap increase...

stock cam idles at around 35 kPa 600 rpm.

[samh_08]

I suppose I should list what mine is first. I am not convinced I should have this little vacuum with my cam setup, which is why I started this thread.

Cam: Texas Speed Torquer V3 Camshaft - 231/234 .643/.598 111
Idle MAP: 56-58 kPa @ 750-850 rpm

[Taz]

I suppose I should list what mine is first. I am not convinced I should have this little vacuum with my cam setup, which is why I started this thread.

Cam: Texas Speed Torquer V3 Camshaft - 231/234 .643/.598 111
Idle MAP: 56-58 kPa @ 750-850 rpm

Idle MAP will be in that range (high 50's kPa) with that cam - the 111 degree lobe separation angle will reduce vacuum / increase MAP at idle. Similar cam, but with 114 degree lobe separation angle in a 6.2 L generally yields 47 - 48 kPa at 825 - 850 RPM idle speed.


Regards,
Taz

[macca33]

I'm at 800rpm with 42-45kPa - cam is 215/223 @111lsa in a H/C LS1.

cheers

[dazzak75]

Mine Idles at 950 - 1000 rpm with 75kpa cam is 251/263 .670 112lsa +3 in an LSX 454

[DrkPhx]

Mine Idles at 950 - 1000 rpm with 75kpa cam is 251/263 .670 112lsa +3 in an LSX 454

Damn. I thought I had no vacuum at idle.:) Mine is at 71 kPa idles at 950 rpms.

[dazzak75]

Damn. I thought I had no vacuum at idle.:) Mine is at 71 kPa idles at 950 rpms.

Just looked another log, and it gets worse, flucturates anywhere up to 80kpa, no wonder it is not the nicest to drive at low rpm.

[Sinister]

I just got mine idling and running. I am now trying to learn how to log some data. How would I go about finding this information? My cam is a 224/230 .581/.588 on a 114. Also, is there a sticky that goes through how to scan. I have been playing with it and have a decent idea but it would be nice to read up on it a little more or have some written info I could validate I am doing it correctly before doing something stupid.

[dazzak75]

To log data you need to go to scan, then to record data, then pick your type of ECU, that is what I do and log straight to the V2, then use the EFILive Explorer to get the information from it.

[Sinister]

Thanks. I am getting there. I have a few issues they are trying to help me with in another thread.

[krisr]

I've got the 224/230/114 XER273 cam in my LS1. I can get it to idle well between 45-48kpa @ 850rpm (M6) @ 14.68 AFR, the trick was to give it about 20° base timing. It idles noticeably rougher at 15° even at 900rpm.

[Rhino79]

Im running a mast vvt cam, 230/244 on a 111 lsa, idle map is around 75 -78 kpa at 850 rpm.

[Jester]

Comp 231/237 112LSA XER lobes, 60-61 kpa @ 750rpm (M6).

[O1Z06]

This thread helped me out to verify as the op intended. Thanks for everyone's input.

My idle is at 68.5 kPa at 900 rpm at 25*. Engine specs in sig, cam specs are: 237/251 115+3 .610/.632 1.7 rocker ratio