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IR manifold for a small block?

Posted By: HotRodDave

IR manifold for a small block? - 12/20/08 04:48 PM

I am bored and ther is too much snowe to drive the cuda so I am kickin around the idea of building an IR manifold for my stroker motor. My question is where is a good source of info about desighn like how long and fat runners should be, side draft or down draft, what carbs work best? Mabey someone knows of a manifold being produced

Motor will be a 414 stroker, mabey bigger if I can come up with more $$$ for a longer stroke. I have a pair of RHS magnum heads or aluminum mopar magnums 1.7 rockers and a XE268 cam. I mostly want to do it because it's different but I still want it to run good.
Posted By: formula S

Re: IR manifold for a small block? - 12/21/08 02:16 AM

I think your going to have A hard time finding carbs big enough. I know guys that run dual 2 barrel 48 webbers on VWs with 120cuin displacement, and they make about 150 to 200 horse power. I dont know how big webbers get, but the VW guys talk about 48s as being the biggest they can get
Posted By: HotRodDave

Re: IR manifold for a small block? - 12/22/08 05:36 AM

I figure if I had 250 CFM intake flow X 8cyl I would need about 2000 CFM, mabey a couple 1000cfm dominators set up with identicle primarys and secondaries. Does any one have experiance with dominators on an IR manifold?
Posted By: formula S

Re: IR manifold for a small block? - 12/22/08 07:31 AM

You need carbs that were designed for I/R use holleys are not, they will not deal with pulse that an I/R set up creates. If you have ever looked at A webber, notice how tall it is, its 2 or 3 times taller than A holley and that is no accident. its made for managing I/R conditions, your going to spend A lot of money on dominators and time on your manifold to find out it wont work. But if you must have an I/R set up you can start here. http://www.ronsfuel.com/single2.cfm you could use their throttle bodies with EFI. you could also try kinsler or hillborn to name A couple. This way you could get the CFM your looking for.
Posted By: Anonymous

Re: IR manifold for a small block? - 12/22/08 07:37 AM

There was at one time Dominators made to suit IR
Dont know the part No. or if they are still available.
Posted By: 1_WILD_RT

Re: IR manifold for a small block? - 12/22/08 07:46 AM

Quote:

There was at one time Dominators made to suit IR
Dont know the part No. or if they are still available.



6214 was made for I/R applications but reversion problems were never solved & Holley killed it...
Posted By: therocks

Re: IR manifold for a small block? - 12/22/08 12:36 PM

what about motorcycle carbs
Posted By: HotRodDave

Re: IR manifold for a small block? - 12/22/08 04:50 PM

I have been looking at some motorcycly carbs but I think they are too small but I don't see flow rateings on them, just MM
Posted By: polyspheric

Re: IR manifold for a small block? - 12/22/08 05:55 PM

The biggest motorcycle carbs TIKO are the S&S Super D, 2-1/4". However, they're side-draft, $$$, have no power circuit, and are intended for a 2 cylinder motor about the size of your cylinders.
You can buy Mikuni with 48mm throats, but over $200. each and IDT that's big enough.
Posted By: 1_WILD_RT

Re: IR manifold for a small block? - 12/22/08 06:07 PM

6214 special venturi on the left...

Attached picture 4894971-IRVenturi.jpg
Posted By: 1_WILD_RT

Re: IR manifold for a small block? - 12/22/08 06:09 PM

6214 velocity stacks...

Attached picture 4894975-IRStacks.jpg
Posted By: HotRodDave

Re: IR manifold for a small block? - 12/22/08 08:46 PM

A side draft may not be out of the question. I thought about getting some kinda air-gap manifold and cutting everything out except the bottom plate and flange area, then weld in some tubes to cross over and sit the carbs on the oposite side valve cover area.

Are those 2cyl motorcycle carbs 1 throat or 2? Are the cylinders the size of mine individually or combined?

A mototrcycle carb may be fine because they are desighned to feed a smaller engine but at two to three times the RPM.

If a carb is going to feed a 25 cubic inch 1 cyl @ 10,000 rpm it should feed my 50 cubic inch cylinder @ 5000 rpm, is that close to correct?
Posted By: dizuster

Re: IR manifold for a small block? - 12/22/08 08:50 PM

Just wondering by why would you even want to do this?...
Posted By: formula S

Re: IR manifold for a small block? - 12/22/08 09:11 PM

Quote:

Just wondering by why would you even want to do this?...

first three words in his orignal post "I am bored"
Posted By: 1_WILD_RT

Re: IR manifold for a small block? - 12/22/08 09:15 PM

Quote:

Quote:

Just wondering by why would you even want to do this?...

first three words in his orignal post "I am bored"



Gonna spent alot of time & money on something thats been problematic & never proven any big gains in the past...

Might be a better idea to take up Bowling..At least every bowler I know drinks...
Posted By: dizuster

Re: IR manifold for a small block? - 12/22/08 09:21 PM

Quote:

Quote:

Just wondering by why would you even want to do this?...

first three words in his orignal post "I am bored"



Yeah but if you were board, don't you think you'd at least try to do something to make the car faster...not slower? lol...
Posted By: 1_WILD_RT

Re: IR manifold for a small block? - 12/22/08 09:35 PM

Quote:

Quote:

Quote:

Just wondering by why would you even want to do this?...

first three words in his orignal post "I am bored "



Yeah but if you were board , don't you think you'd at least try to do something to make the car faster...not slower? lol...



Must have wood....
Posted By: therocks

Re: IR manifold for a small block? - 12/22/08 10:38 PM

The s&s super carbs you can run em on one cyl or two and they put the on 120in motors that only turn about 6000
Posted By: polyspheric

Re: IR manifold for a small block? - 12/22/08 11:21 PM

A side draft may not be out of the question. I thought about getting some kinda air-gap manifold and cutting everything out except the bottom plate and flange area, then weld in some tubes to cross over and sit the carbs on the oposite side valve cover area.

Are those 2cyl motorcycle carbs 1 throat or 2?
All 1 throat

Are the cylinders the size of mine individually or combined?
Each

If a carb is going to feed a 25 cubic inch 1 cyl @ 10,000 rpm it should feed my 50 cubic inch cylinder @ 5000 rpm, is that close to correct?
Yes, I know that's what the "formula" shows, but it doesn't work. The small cylinder need a small carb or it has poor response, the big cylinder needs a big carb or it has no power.

Cutting off everything but the flange and chunk of the runner and extending them across is exactly what a 1960-61 Chrysler long ram runners look like (except they ended in plenums). There are also Moon Weber manifolds like that - there's no other way to hide the length and put the hood on.

I agree - it's a lot of trouble without much gain - and that's if you get it right. Most people give up after much $$$ and &<?$@~`**!!!!.
Posted By: Jerry

Re: IR manifold for a small block? - 12/23/08 04:21 AM

why not efi the setup? that way you can still run the IR manifold with individual throttle bodies and youre at least guaranteed a workable solution at the end.
Posted By: HotRodDave

Re: IR manifold for a small block? - 12/23/08 04:40 AM

I helped a friend last winter put a 1000 suzuki motorcycle carb on a 2.0 litre D-50 engine with a home made IR manifold and it ran pretty good

The reason for a IR manifold is driveability, you can run a big cam to make HP and still get it to idle smooth. It helps smooth out the TQ curve, low rpms the cylinders are not trying to pull the breath out of another cylinder and massive airflow at high rpms.

I think it could be fast, driveable and look awesome if done right

Right now there is about 18 inches snow on the roof of the cuda so.... wher is the twidling thumbs smiley?
Posted By: GomangoCuda

Re: IR manifold for a small block? - 12/23/08 06:38 PM

Quote:

The reason for a IR manifold is driveability, you can run a big cam to make HP and still get it to idle smooth. It helps smooth out the TQ curve, low rpms the cylinders are not trying to pull the breath out of another cylinder and massive airflow at high rpms.

I think it could be fast, driveable and look awesome if done right


For some reason I am thinking that if it had all those advantages it wouldn't have been abandoned over 30 years ago.

If you go to Hilborn's or Kinsler's websites you will see many variations of Small block IR fuel injection systems. Typical throttle bore sizes are way bigger than any available carburator. 2 7/16" - 2 5/8" are common and they can be as big as 3". At least with F.I. the pulseing that goes on in an IR arrangement doesn't disrupt fuel delivery like it does in carburetors. The bottom line is that the reason they quit using IR manifolds back in the day is because everyone that put a plenom on top of their IR manifold went faster.
Posted By: Rug_Trucker

Re: IR manifold for a small block? - 12/23/08 06:39 PM

Quote:



Right now there is about 18 inches snow on the roof of the cuda so.... wher is the twidling thumbs smiley?



Why isn't it in the garage?

You and I have had this discussion when you were living here. Maybe run 8 VW Solex carbs?
Posted By: HotRodDave

Re: IR manifold for a small block? - 12/23/08 06:49 PM

Well I got my wife pregnant 8 months ago and it is cold and slipery out side so she gets to use the garage, wasn't thinking ahead was I
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