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apexrig1 03-25-2012 06:03 PM

Blown Engine Build Help
 
hello everyone,
I was hoping to gain some insight if I could. I've never built a blown engine but understand the concepts needed to achieve it. Or so I think.... anyways my original plan was to build a 540 engine with a 8-71 and go the efi route with the bugcatcher scoop that hilborn injection or bds provide.But the more i research that you can't have any form of an air filter in these hats is discouraging. Now Im hoping someone can tell me that there is some sort of filter that will go inside as I won't be putting the external filter on. Just a personal preference on looks.
So I got looking into these streetcatcher scoops that are quite sharp looking i'll have to say regardless it is a phony looking fi setup, but like I said Im aiming for a look. But then the problem comes that you can only use a single 4150 style carb and the largest holley I can see boost referenced is a 950cfm and Im most certain that just won't do for that size of engine. I would rather build a smaller engine9but still a big block) vs going to a dual carb setup but also want a good number when it goes on the dyno.

So long story short
Is there a way to have a filter inside the hat on a efi setup?
What size of motor can I run a single carb on with a 8-71 blower?
Also is there any other options/opinions?

Thanks for your time, Matt

F-BIRD'88 03-25-2012 06:15 PM

Do not even think about using a single carb on a 6-71 or 871 style blower.
They don't work. Poor fuel distribution.

If you run with no air filter you can expect accelerated engine wear.

apexrig1 03-25-2012 09:16 PM

Oh really we'll that is not what I wanted to hear. Not even okay for street use?

bentwings 03-25-2012 10:27 PM

While I don't have as large of motor as you are proposing I run a BDS scoop and 2 K&N oil spray air cleaners. This scoop is the quite a bit larger than the traditional "Hilborn scoop". It's great for catching large dragon flies. haha

I have just over 19k miles now and no problems at all.

You have to remember that there is really very little air going into the motor when cruising. It only takes 50-60 hp to go 60 mph unless it is really windy or you have big truck. I cruise a lot in the rain too and we do get on gravel roads occasionally. Still the dirt I get out of the air cleaners is very small.....hopefully it is not going into the motor. haha These K&N AC are pretty good I think. They can get real dirty on the graveol roads but so do my unblown friends with their BBC's and 383 SBC's with the larger K&N air cleaners. We compare notes all the time.

I fail to see why an EFI doesn't take into account the mass of air coming into the system. I can see WOT throttle being a bit choked with the small AC's but I you are going to the track just take them out if you want. I would think the EFI sensors would compensate for this. If not stick with the carbs. Mine sure work great. 5 deg F to 103 last year and no adjustments anywhere. I even got a little snow in the scoop this year in Jan.

And BTW I've looked at most of the popular blower EFI''s that go on x-71 style blowers. I've yet to see one run well out of the box. If some has one or has experienced this, I would love to hear all about it.

4 Jaw Chuck 03-25-2012 11:36 PM

Why would you want to run a single carb on an 8-71? What would be the point of choking a huge blower with a single carb?

Is this simply a "look" your trying to achieve?

apexrig1 03-26-2012 05:50 PM

A little bit of everything, look, sound, performance. Just always liked the looks of a fi bugcatcher.

NOlowrider 03-26-2012 07:13 PM

I can't speak as to the FI route, never been there. However, I think trying to run a 540 with an 8-71 on one carb would be a big mistake. Listen to the previous advice. These guys know what they are talking about. I have a 454 and I am running 1900 cfm total between the two carbs. Choking it down would be asking for trouble. IMO. The worst thing you can do is run a blower motor lean. Let that sucka breath. Plus, I think it would look goofy. :nono:

against all odds 03-26-2012 07:37 PM

i've been wondering about this dilema myself.

My view is that the only way it can be done is to make a "tray" to house a flat filter that will go between/under the hat and on top of the blower. If fuel is going to be injected into the blower, then the tray must go under the hat but before/above the fuel block.

a) If the filter does cause a restriction (would it really be that high a restriction.....?) then can't we comphensate for that by adding a little more boost? i'd be willing to sacrifice a little power for protection. Has anyone actually shown how much (if any) restriction an inside filter really poses?

2) As far as the streetcatcher thing; My feelings on these products can be summed up in a not so nice word that begins with a "W" and ends with ing. If you're going to do something, then do it the right way. On the other hand, if it's looks you're after then i suppose they're ok. i'm actually suprised D.G. would have these things on his website.

apexrig1 03-26-2012 08:08 PM

I had planned on doing it the "right way" but after finding about the lack of filter in the hat was quite discouraged. So just looking at other options. As many people would say it would be lame to run the streetcatcher setup. Maybe it is. But it's an option and I like to think it does look quite sharp. And I would never plan on trying the single carb on a 540. If the efi won't pan out I would be probably going alot smaller. Probably 396 with the 950cfm carb. But right now it's just in the planning phase. So you know how that goes!

NOlowrider 03-26-2012 08:57 PM

I wouldn't even run a 396 with only the one 950. Like Fbird said, its a matter of fuel distribution. Maybe two 600's or 700's. That's just my opinion though.

I think the Streetcatcher looks cool, I don't know anyone that has one or know how they perform. They have some nice rides on the site that run them, so I guess you can do it.

http://www.alsblowers.com/sc500/cooper55.htm

http://www.alsblowers.com/streetcatcher.html

4 Jaw Chuck 03-26-2012 09:09 PM

You can buy filters for Hillborn style hats, Jegs sells them!

http://www.jegs.com/webapp/wcs/store...-1&showValue=1

I'm confused?

apexrig1 03-26-2012 09:44 PM

Sorry for the confusion. It's an enderle 3 hole style hat. Reason why I said hilborn was because I was looking at the hilborn electric fuel injection kit.

Michaelelcano 03-26-2012 10:20 PM

Read these 2 pages. The guy had the exact same issue as you and had an interesting solution.
http://www.project33.com/article.cfm?ID=348
http://www.project33.com/article.cfm?ID=349

against all odds 03-26-2012 11:27 PM

Thanks for the article links. Admitedly, i had never actually tried what they did---i only "thought" it might be possible. i was thinking about going back to tunnel ram and 2 carbs and abandonning the injector idea, but after reading the article, there is renewed hope.

Do you know where they/he/she is injecting the fuel?

Michaelelcano 03-26-2012 11:30 PM

He is using an out of the box bds system. The injectors sit in a plate that sits between the bugcatcher and the blower.


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