BMW M3 Forum
BMW M3 Forum BMW M3 Gallery BMW M3 Reviews BMW M3 Social Groups BMW M3 Chat M3Forum Sponsors >>

Mobile M3forum
Go Back   BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X) > BMW M3 Discussions > M3 Frequently Asked Questions > E46 FAQ
Tire Rack Buy Winter Tires Now!
Not a member? Register Now!
Register Gallery All Albums Garage Search Today's Posts Mark Forums Read Calendar FAQ

Thread Tools Display Modes
Old Tue, May-03-2005, 04:09:06 PM   #31
Super Gyros
Got Idz21?
Super Gyros's Avatar
Join Date: Dec 2002
Age: 41
Posts: 21,730
Reputation: 0 Super Gyros is on a distinguished road
Location: Athens



That is a nice thread. Since we already have two people writing about superchargers, I should write about turbo right?
Jump to top Super Gyros is offline   Reply With Quote
Sponsored Links
Register now and remove these ads
Old Tue, May-03-2005, 05:42:27 PM   #32
Beowoulf's Avatar
Join Date: Jul 2003
Posts: 24,703
Reputation: 0 Beowoulf has disabled reputation
Location: In the woods

United Nations


Originally Posted by Kaiser Sausage
That is a nice thread. Since we already have two people writing about superchargers, I should write about turbo right?
Go for it. Start another thread.

Jump to top Beowoulf is offline   Reply With Quote
Old Tue, May-03-2005, 09:53:51 PM   #33
Look out below!
Join Date: Aug 2003
Age: 50
Posts: 7,324
Reputation: 0 Mash3 is a jewel in the rough
Location: Hollywierd

United States


So what's an optimal A/F ratio for a S/C'd M3? Consider both a "simple" bolt-on kit and a complete ground-up engine rebuild install.

And would the A/F have to be constant or could it vary, depending on throttle position and rpms? (Idle vs WOT@ 8,500rpm)

Hope I'm not asking a question that has already been answered.


Forum Member Since 2003.
. . 2004 M3, SG/ IR. No sunroof. 6MT. MCS SA. 18" Squares. Z4M rack. 130,000k miles. Original owner.
Jump to top Mash3 is offline   Reply With Quote
Old Wed, May-18-2005, 06:11:42 AM   #34
Registered User
Join Date: May 2005
Posts: 53
Reputation: 0 Dont8 is on a distinguished road


I totally agree with ArtM3, without dragging this any further. Lowering the compression ratio will definitely increase the lifespan of a F/I engine. It may not be required for a mass produced F/I engine application, because the average individual is looking for longevity of their vehicle. That is why their boost levels are usually low between 5 to 9 psi. Higher boosts almost always require lowering your compression ratio. It's almost common sense!

Originally Posted by ArtM3
I was comm'ing with Osh &

the main point: in a NA engine the main force for filling the cylinder is atm press ~ 14.7 lbs

in a forced induction engine with 1 atm of boost, you'll stuff twice (1 atm + 1atm) as much charge into it, and twice as much power...

if you have 1/2 atm boost (~7.5 psi) you'll have (1 + 1/2 ~150%) more power, this is pretty accurate, if you ignore losses due to flow restriction, etc.

in summary:
Bogie gets (1 + 11/14.7 atm) or 175% more power
Scott gets (1 + 7.5/14.7 atm) or 150% more power
or Bogie shoul get 25% MORE than Scott...
1.25 x 380hp(Scott @ 6700) = 475hp vs Bogies 473 dyno, pretty damn close

the point being, the claimed hp is plausible, and with the reduction in compression (IMO essential, especially on an 11.5:1 Cr) and some better headbolts/gasket, should be very reliable, probably more so than an engine without the Cr reduction...more power AND robustness, pretty damn impressive, but not magic, just good, sound, engineering practice...
Jump to top Dont8 is offline   Reply With Quote
Old Fri, May-20-2005, 08:37:44 PM   #35
Registered User
Join Date: May 2005
Posts: 5
Reputation: 0 chancha is on a distinguished road

Default great stuff.......

Great topic on here regarding the forced induction stuff..... some of it really brought home some of the work I did when I upgraded my audi ur-quatto 20v engine....... I know you guys in the states never got this version of engine but all this talk of reducing compression ratios, boost levels not being the absolute be all and end all is true..... after I had finished the engine was pushing about E46 levels of hp but 400lb/ft of torque..... and to be honest comparing it to my e46 m3 there was only one winner in the grin factor stakes.... ok I know it's an audi but really the engine was only 2.2 litre capacity-).......... keep up the good work guys!!!!
Jump to top chancha is offline   Reply With Quote
Old Tue, Sep-28-2010, 08:01:22 PM   #36
Registered User
Join Date: Sep 2010
Posts: 1
Reputation: 0 SLVRSFR is on a distinguished road

United States


Thanks. Excellent posting. I suppose I should have read this prior to installing:-)

E46 2003 M3: VFE Supercharger Stage 1, Bilstein PS10, Stoptech 380, TMS Underpulley, Dixi Titanium Exhaust, X-pipe, ++
Jump to top SLVRSFR is offline   Reply With Quote
Old Sat, Feb-23-2013, 03:42:55 PM   #37
m3 hammerdown
Registered User
Join Date: Oct 2004
Posts: 243
Reputation: 0 m3 hammerdown is on a distinguished road

Default Re: Forced Induction for Dummies

Wow I just came across this thread on the internet in a random search for something else. I haven't been here in more M3......but hi guys, 8 years later! LOL
Crush your enemies and see them driven before you
Jump to top m3 hammerdown is offline   Reply With Quote


dummies, forced, induction

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Forced Induction San Diego M3 Forced Induction (F/I) 8 Thu, Mar-10-2005 06:24:49 AM
Forced induction?? ///M3power Forced Induction (F/I) 4 Sat, Jan-15-2005 10:22:43 PM
Forced Induction on M3 marv800 Forced Induction (F/I) 2 Tue, Mar-30-2004 12:01:00 AM
forced induction? g2pinoy Forced Induction (F/I) 9 Mon, Oct-27-2003 05:18:57 PM
M3 Forced Induction AnM3forMe Forced Induction (F/I) 2 Wed, Feb-05-2003 01:53:10 PM

All times are GMT. The time now is 03:39:00 AM.

Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd. and is in no way sponsored, endorsed or affiliated by or with BMW NA / BMW AG or any of it's subsidiaries or vendors.
BMW and M3 (E90 M3 | E92 M3 | E93 M3 | E46 M3 | E36 M3 | E30 M3) are registered trademarks of BMW AG.
M3Forum Terms of Service
Copyright 1999-2017
Discussing Forced Induction for Dummies in the E46 FAQ Forum - at BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)