Re: Roots Blower EFI ?
[Re: Dragula]
#875527
12/09/10 02:34 PM
12/09/10 02:34 PM
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Joined: Jul 2010
Posts: 1,845
Tampa
DusterDave
top fuel
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top fuel
Joined: Jul 2010
Posts: 1,845
Tampa
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Quote:
Which way is better to fuel the engine, injectors above the blower, or below, or both? Why?
Depends on the fuel. If it's E85 or alky, I'd do both, because you'll want to cool the blower with it, and the large quantity distributed over many injectors allows for smaller injectors. This is all pure conjecture, BTW. But, it sounds good to me, and that's the way I'd do it.
Gone to the dark side with an LS3 powered '57 Chevy 210
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Re: Roots Blower EFI ?
[Re: Dragula]
#875528
12/09/10 02:58 PM
12/09/10 02:58 PM
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Joined: Jan 2003
Posts: 1,938
Sonora CA
Mopar_Rich
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,938
Sonora CA
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Quote:
Which way is better to fuel the engine, injectors above the blower, or below, or both? Why?
Randy,
We talked about this before - haven't we?
I ALWAYS inject above AND below the blower. I have built quite a few engines with EFI injectors only above the blower and they are always harder to tune. In two cases I took engines that had injectors only above the blower and then retrofitted injectors below the blower and everything got better. The only way I would ever inject only above the blower is in an all out racing application where part throttle drivabilty didn't matter.
If the blower was of the type that didn't need any fuel going through it for cooling (yes, there are a few) I wouldn't use injectors above the blower at all.
There is just NO BENEFIT to using all the extra fuel to wet down the blower, and the manifold, and all the other internal walls, if you don't have to. I had a HEMI about 9 years back that BDS did the injection (only above). That POS would only run when it was hot. Cold start and cool running was worse than a carb. We had to run at 11:5 A/F ratio to get any drivabilty at all. After adding the lower injectors, it started cold, ran cold, and cruised at about 13.5:1 A/F ratio. It's still running today.
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Re: Roots Blower EFI ?
[Re: Mopar_Rich]
#875529
12/09/10 05:55 PM
12/09/10 05:55 PM
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Joined: Sep 2007
Posts: 576
Escondido, CA
kick_the_reverb
mopar
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mopar
Joined: Sep 2007
Posts: 576
Escondido, CA
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I have a question, would the manifold injectors need to be on a different branch of the fuel system so they could be boost referenced. I'm assuming you don't want to boost reference the top ones since they are injecting into non compressed air.
Thanks,
Ran
"Hey mister, something's wrong with your car, it idles roughly" - number one comment I got in Israel when daily driving a 70 Barracuda with a lopey cam.
Currently working on - 1966 Dodge A100 van 318/auto
Finally - disc brakes on the front.
In the plans - rear disc brakes, B&M 250 blower
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Re: Roots Blower EFI ?
[Re: Mopar_Rich]
#875531
12/09/10 11:23 PM
12/09/10 11:23 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I'd leave the full system boost referenced. The tune will easily make up for the pressure difference.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Roots Blower EFI ?
[Re: feets]
#875532
12/10/10 05:10 AM
12/10/10 05:10 AM
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Joined: Sep 2007
Posts: 576
Escondido, CA
kick_the_reverb
mopar
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mopar
Joined: Sep 2007
Posts: 576
Escondido, CA
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Thanks, makes sense that you can take care of it with the tune. Simpler for sure.
Ran
"Hey mister, something's wrong with your car, it idles roughly" - number one comment I got in Israel when daily driving a 70 Barracuda with a lopey cam.
Currently working on - 1966 Dodge A100 van 318/auto
Finally - disc brakes on the front.
In the plans - rear disc brakes, B&M 250 blower
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