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Most people run mechanical on top of the blower. No law says you can not run port injection (as in EFI); but the fuel dumped in on top helps cool the roots style blower. Centripetal blowers are usually force feeding an EFI set up (if fuel injected otherwise its a blow through carb), which requires bigger injectors and a programmable controller to set the fuel air map.

Need more info to get more specific.

Larger Dave
 

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Discussion Starter · #6 ·
I'm going with a twin screw superchager. So, the whole roots blower idea is out the window. Besides, I'm not a fan of the roots blower. And oh yeah, I am going with aftermarket feul injectors. I may go with 60 lbs. injectors just to be safe and make sure I don't starve the engine.
 

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I'm going with a twin screw superchager. So, the whole roots blower idea is out the window. Besides, I'm not a fan of the roots blower. And oh yeah, I am going with aftermarket feul injectors. I may go with 60 lbs. injectors just to be safe and make sure I don't starve the engine.

I always considered the twin screw as a roots-style blower. I ran one on a Lightning, worked well. As far as EFI there are several that will run your engine, depending on features you want and cost. FAST, Accel, Holley, Big Stuff 3 are probably the most popular aftermarket systems and all can run a supercharged small block.

Jody
 

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Hi Jody i just bought my D1SC kit for my 427 small block , i run 36lb injectors now , what size once the blower is on . i'm just tuning the Wide band upgrade it seems to make more sence than the old setup .should make it better with the blower .
Mark.
Mark. I need a HP goal to figure the injector size needed. Your 36's are good for about 450-500 hp, depending on fuel pressure, how far you want to push the duty cycle, and bsfc. In general terms a 60# injector is very safe at 650 hp and will support 750 hp or so on a supercharged engine at 90% duty cycle. We used 75's in the 700 rwhp 406 and were plenty safe. There's really not an issue using a larger injector (within reason) with the good aftermarket efi systems, and gives more room for growth and a safety factor.

Jody
 

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Jody between 700-750 would make me smile from ear to ear . It should be easy to get there with motor i think , i had some more flow work done on the brodix heads , so we shouldn't need to go major boost levels to get those numbers . I want to stay with the solid roller but go a bit smaller to make it more street friendly , i will need to talk to you about what we need for a cam to work with the blower and the fuel injection .
Mark.
 

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Discussion Starter · #11 ·
Just to clear something up. The roots style blower is the basic way of supercharging your engine and is not very efficient. Yes, the roots and twin screw superchargers blow air in. However, they use different meshing lobes to do this. A roots blower basically jsut blows more air into the engine...hence the term "blower." Another thing is the efficiency of the roots blower. See, the blower is the least efficient because it moves air into the engine in discrete burst and not a smooth continuous motion. But, the twin screw...operates by using a pair of meshing lobes that resemble worm gears. There is a male and female gear. The advantage of a twin screw is that it compresses the air inside the rotor housing due to the conical taper. Oh and another advantage...at least in my eyes...it's loud as hell. lol That's the difference between the roots and twin screw superchargers. I did leave out the last kind of supercharger and that's the centrifugal one but oh well.
 

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Just to clear something up. The roots style blower is the basic way of supercharging your engine and is not very efficient. Yes, the roots and twin screw superchargers blow air in. However, they use different meshing lobes to do this. A roots blower basically jsut blows more air into the engine...hence the term "blower." Another thing is the efficiency of the roots blower. See, the blower is the least efficient because it moves air into the engine in discrete burst and not a smooth continuous motion. But, the twin screw...operates by using a pair of meshing lobes that resemble worm gears. There is a male and female gear. The advantage of a twin screw is that it compresses the air inside the rotor housing due to the conical taper. Oh and another advantage...at least in my eyes...it's loud as hell. lol That's the difference between the roots and twin screw superchargers. I did leave out the last kind of supercharger and that's the centrifugal one but oh well.

I understand that. ;) I've had a "couple" blower setups. It's just a general term I use, like calling an engine a motor. I know it isn't correct but it works for me.


Jody
 

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Discussion Starter · #13 ·
Oh...ok. Sorry about that man. I just get a little touchy on the subject of superchargers and twin turbos. lol However, you do make a good point when you refer to engines as motors. But yeah...I think running an aftermarket EFI system with the supercharger along with 60lbs injectors would be the best way to go. If you guys have any more info...it would be much appreciated. :)
 

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Re: Supercharged fuel injection?

. There's really not an issue using a larger injector (within reason) with the good aftermarket efi systems, and gives more room for growth and a safety factor.
Jody
Agreed:thumbsup: A little bigger is better. On my data logs I'm seeing 95% duty cycle at peek RPM, with 750cc/72# injectors, making around 800 hp. Thats at a very safe/rich 10.6 to 11. AFR, and only for a split second above 6800rpm.
I should probably go to 85lb injectors?? ---Bill.
 

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Discussion Starter · #15 ·
10.6? Man! I'm going to stay around a c/r of 8.5 to 9 without the twin screw on top. This should be better when I supercharge it...not to mention, if I go too high with the c/r...race feul would be my only feul. lol I'm staying with pump gas. Oh yeah...I think that the 60lbs injectors would be a nice fit since I'll be pushing around 550 to 600 RWHP with the twin screw and between 400 and 450 without. However, should I be safe using the 60lbs injectors before I go with the supercharger...or is there no need to worry? Just wondering because I will have to beak the engine in before I put the twin screw on but I don't feel like buying two different injectors...one before and one after supercharger. Any ideas?
 

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10.6? Man! I'm going to stay around a c/r of 8.5 to 9 without the twin screw on top. This should be better when I supercharge it...not to mention, if I go too high with the c/r...race feul would be my only feul. lol I'm staying with pump gas. Oh yeah...I think that the 60lbs injectors would be a nice fit since I'll be pushing around 550 to 600 RWHP with the twin screw and between 400 and 450 without. However, should I be safe using the 60lbs injectors before I go with the supercharger...or is there no need to worry? Just wondering because I will have to beak the engine in before I put the twin screw on but I don't feel like buying two different injectors...one before and one after supercharger. Any ideas?
His 10.6 was a/f not compression. I'd do it once with the 60's, they can be tuned fine with the milder "motor" :D and then re-tune after the blower. I wouldn't buy two sets of injectors.

Jody
 

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Re: Supercharged fuel injection?

Agreed:thumbsup: A little bigger is better. On my data logs I'm seeing 95% duty cycle at peek RPM, with 750cc/72# injectors, making around 800 hp. Thats at a very safe/rich 10.6 to 11. AFR, and only for a split second above 6800rpm.
I should probably go to 85lb injectors?? ---Bill.

yeah 95% dc is high. Either up the fuel pressure or a bit larger injector would work.

Jody
 

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Discussion Starter · #19 ·
I meant fuel! lol Thanks for letting me know that I spell for ****! lol But thanks for the advice guys. I think I'll go with what you guys said and get the 60lbs injectors and have tehm tuned for a mild motor...until I get the blower. :)
 
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