Updraft or downdraft on 220 conv?

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Bangin6
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Updraft or downdraft on 220 conv?

Postby Bangin6 » Tue Jul 01, 2014 3:03 pm

I have a 2 barrel which runs good on stock setup now. I know it's mostly opinions but what would be more positive with updraft over a downdraft besides saving $? I've seen a few Intakes made to work with a Holley. I should be getting at the 470 angle valve conversion soon. Trying to see what more to buy if needed. All input is welcome.

Thanks, Dan
12' hamant, single mag 220 gpu, Sensenich 2 blade NGH. Working on the a/v conversion.


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broncobill
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Re: Updraft or downdraft on 220 conv?

Postby broncobill » Tue Jul 01, 2014 3:14 pm

My first question would be, Why? Why 0470 conversion? It is already 470 in cubic inches. Do you just want the reliability of aircraft cylinders maybe dual mags. Will not get much more RPM out of a 0470 than you have now. And if were talking durability, you still have a GPU crank. Your money would be better spent on adding more HP by adding Lycoming rods or High compression pistons or doing a 520 conversion then your question would be GITSO or Angle Valve 520 cylinders.

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Bruce
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Re: Updraft or downdraft on 220 conv?

Postby Bruce » Tue Jul 01, 2014 6:42 pm

broncobill wrote:My first question would be, Why? Why 0470 conversion? It is already 470 in cubic inches. Do you just want the reliability of aircraft cylinders maybe dual mags. Will not get much more RPM out of a 0470 than you have now. And if were talking durability, you still have a GPU crank. Your money would be better spent on adding more HP by adding Lycoming rods or High compression pistons or doing a 520 conversion then your question would be GITSO or Angle Valve 520 cylinders.


I disagree id do the 470 conversion over lycoming rods or high comp pistons in a pos gpu cylinder anyday they make great motors and to answer the original question updraft all the way theyre more responsive, get better economy, and you have a lean rich to shut it down
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broncobill
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Re: Updraft or downdraft on 220 conv?

Postby broncobill » Tue Jul 01, 2014 7:09 pm

Go for it! 100 rpm per $1000. Sounds good to me. I'd do it! LOL

Bangin6
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Re: Updraft or downdraft on 220 conv?

Postby Bangin6 » Tue Jul 01, 2014 10:25 pm

I have 7 chrome angle valve jugs and popups waiting to go on already. I Was gonna try to save a little on the carb but since u put it that way Bruce, I'm gonna have to find an updraft. I would guess Ma4-5?
12' hamant, single mag 220 gpu, Sensenich 2 blade NGH. Working on the a/v conversion.


I don't like jail, they got the wrong kind of bars in there -Charles Bukowski

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goldhunter_2
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Re: Updraft or downdraft on 220 conv?

Postby goldhunter_2 » Tue Jul 01, 2014 10:36 pm

updraft is better but downdraft is more common
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LJohnson
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Re: Updraft or downdraft on 220 conv?

Postby LJohnson » Tue Jul 01, 2014 11:07 pm

I have no intention on doing a conversion any time soon, mine is stock now. In my personal opinion though, if I were to convert, I like the idea of 520 gitsu cylinders. You gain almost double the horsepower, you have the advantage of the strong GPU camshaft from the original setup, and the intake is on top like the stock GPU setup. Plus they look cool.
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Comanche-pup
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Re: Updraft or downdraft on 220 conv?

Postby Comanche-pup » Wed Jul 02, 2014 9:08 am

I can attest, high compression pistons in a stock GPU cylinder is a nightmare! Valves galore, nothing but a headache


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John Fenner
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Re: Updraft or downdraft on 220 conv?

Postby John Fenner » Wed Jul 02, 2014 10:27 am

I would run the Holley, you can tune it better than an updraft plus your mileage will be better, my conversion has 470 jugs, 8.6:1 and a 500 Holley with 73 jets, it runs strong and burns very little fuel.
I never finish anyth,,,.

Bangin6
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Re: Updraft or downdraft on 220 conv?

Postby Bangin6 » Wed Jul 02, 2014 10:29 am

Do you have a pics of your intake setup, John?
12' hamant, single mag 220 gpu, Sensenich 2 blade NGH. Working on the a/v conversion.


I don't like jail, they got the wrong kind of bars in there -Charles Bukowski

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John Fenner
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Re: Updraft or downdraft on 220 conv?

Postby John Fenner » Wed Jul 02, 2014 12:35 pm

Somewhere, might be in my old phone I will look.
I never finish anyth,,,.

broncobill
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Re: Updraft or downdraft on 220 conv?

Postby broncobill » Wed Jul 02, 2014 1:08 pm

I ran high compression pistons for many years no problems as long as you run A/V gas and didn't do a whole bunch of dry running without letting it cool. Make sure you run a CHT.

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John Fenner
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Re: Updraft or downdraft on 220 conv?

Postby John Fenner » Wed Jul 02, 2014 1:31 pm

Trying to upload a picture but not working.
I never finish anyth,,,.

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John Fenner
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Re: Updraft or downdraft on 220 conv?

Postby John Fenner » Wed Jul 02, 2014 1:42 pm

I never finish anyth,,,.


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