why do blower engines surge at idle?
 

is this a carb only thing? or will EFI motors do the same thing?

Re: why do blower engines surge at idle?
 

My understanding is carbed engines that are blown tend to surge a little because of puddling of gas in the plenum and runners... probably not the same with EFI...

Re: why do blower engines surge at idle?
 

Check idle circuit, to rich at idle :cool:

Re: why do blower engines surge at idle?
 

If they are tuned right they dont surge. EFI blown engines that i have had experience with idle like a stock engine. All the carb blown engines seem to have a really hard time when moving from there tuned location since the air changes so much.

Re: why do blower engines surge at idle?
 

500 HP Mercedes Benz AMG's don't.

Re: why do blower engines surge at idle?
 

Any engine will surge or lope or roll if its too rich at idle. A blower just amplifies the situation.

Re: why do blower engines surge at idle?
 

The Sorcerer is injected and has a slight blower surge...

Re: why do blower engines surge at idle?
 

My 99 Suburban acts like it has blower surge. Drives me crazy.

Re: why do blower engines surge at idle?
 

I have PSI screw blowers, with a pr. of 4150 series Holley 1000+ carbs on 572c.i. motors that surged @ idle on the dyno when we 1st built them 4 years ago.
I leaned the idle circuit, as suggested above, and the surging went away.
The only problem that I ran into, when they are in the boat and in the water, is when you put it into gear, the engine dies. I screwed the idle mixture screws out a "tad" and it went back to surging, but quit dieing.
I guess that I will put up with the surging.

Re: why do blower engines surge at idle?
 

I have the exact situations as described above. When I installed new blower motors in the boat. I was getting a surge from 700 well beyond 1200.
I run twin 850 demons with Monneyham 10-71,s intercooled. overdriven 15%
If I lean the carbs. Screw in the eight mixture screws the surge will go away
But as soon as you put into gear stalls engine. I managed to just get them
to want to idle without dying in gear.

Possible Causes of surge. (Rich Lean, Rich Lean,Rich Lean)
To rich Idle circuit (like Reed Jenesen Suggested puddling of fuel)
Timing not locked out.
Power valve not right opening and closing intensifying surge.
Butterflys not set evenly
A heavier flywheel may counteract the surge.

I ended up going to the Barry Grant and Holley websites and read
the procedures for setting idle. Basicaly took the carbs off and followed
the procedures Exactly. (setting Idle transfer Slots).
This Helped, But to this day I still get a slight Blower roll that if left to idle
will even out.
Sterling makes a solenoid that whacks the Accelerator pump the moment you put it in gear to give that extra fuel just when you need it.
Then you could lean it without surge and not worry when you are moving around the docks.

Hope this helps
Gerry