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Racing Beat,12a Holley Intake manifold To Nikki Caby?

Any type of technical questions or info

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Rota_Motor
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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#21 Post by Rota_Motor » Sat Jul 03, 2010 11:46 am

rotor_wizard wrote:even with a monster port.. a 450 4bbl holley with right jet size on that racing beat manifold,would feed enough. problem solved. :mrgreen:
From memory the RB site recommends a 465CFM for stock and street portee enginwes, but a 650CFM for bridges etc.

From what I manmaged to learn from experienced racers in the states, a Holley needs to be relatively oversized to work well on a rotor due to the different airflow characteristics when compared to a V8, I think the more pyulsating effect nedsds bigger CFM for the peak flow from the induction pulses.


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#22 Post by Dazz » Sat Jul 03, 2010 12:31 pm

I wonder if having the four runners entering the plenum on a slight angle (45 degrees to the butterflies) with a nice radius on the entry or even a bell mouth would be worthwhile.

With an stock or extend port you would get a pulse back up the runner as the rotor close the port off, so having some pulse tuning whereby it the pushes a pressure wave down the opposite runner may be beneficial as well. Although that may not work as well with a carby as with efi as this may interfere with the signal to the carby.

Worth thinking about in any case.


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#23 Post by Rota_Motor » Sat Jul 03, 2010 1:01 pm

Things like bellmouths etc. work well with injection, but the problem with a carby is you need to keep airspeed up so the fuel stays in suspension, and if you have a bellmouth, you end up with the bottom of the plenum covered with fuel up to the level of the bellmouths... or so I should imagine.

I havent used my RB intake much yet, and when I do use it I wouldnt mind making it work better, but I'm a little hesitant to take to it with a porting tool since they arent really cheap, but mostly because they arent particularly easy to find.


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#24 Post by Dazz » Fri Jul 09, 2010 8:57 pm

Interesting porting job?

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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#25 Post by snocone » Sun Sep 11, 2011 6:35 am

Is there any power gain in running a racing beat manifold with a stock 4 barrel rx4 carby?
Im thinking about replacing my stock manifold with a racing beat manifold on my rx4 13b mild port.

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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#26 Post by bumpstart » Sun Sep 11, 2011 11:04 am

racing beat manifold is for the wider holley,, doubt the nikki will fit on
racing beat manifold is also much wider than the stock one and clashes with clutch and brake booster when used in some smaller rx RHD vehicles

rx4 is OK,, so is rx7 s1 ,,else not
though if you have a s4/5 onwards engine with adapter plate you may find things very close

also the RB holley is much modified to suit the rotor ,, out of the box the average aussie holley is a huge PITA to put right

IMO the weber is a hands down winner over these for ease and result and looks
but can never give the economy of a 4 barrel running off only the primaries

i found all this out the hard way in the middle 90's

there is no re-inventing the wheel, crap is still craptastic


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#27 Post by snocone » Sun Sep 11, 2011 11:11 am

ok fair enough. however im told that the RB manifold can be drilled and tapped to accomodate the rx4 carby.
I have an rx4 with an rx4 type 13b motor so clearance should not be an issue.

Im told the only thing holding the rx4 4 barrel back is the stock manifold and will flow alot better with the RB manifold??



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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#28 Post by 74Rx4Wagon » Sun Sep 11, 2011 11:22 am

This is as good a place as any to let people know I'm looking for a RB 465 holley complete kit to put on my 12A RX7, so if someone has one, please PM me.

I've placed a request along the same lines in the Parts WTD area, so just putting here in case peeps don't read the other area.

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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#29 Post by bumpstart » Sun Sep 11, 2011 11:28 am

most stock carb manifolds are crap compromises

the hitachi ( 13b ) carb is wider spread than the nikki,, but not as wide as the holley
it is possible they may be made to fit
though expect the compromise in the cross porting under the carb may negate any benefits from the rest of the manifold swap

if you want a better manifold for your hitachi carb then you should search out a rare manifold from the US that was fitted to some rx5 and maybe some REPU

this manifold is reversed

you read correctly
the engine fitted with this manifold originally came as 4 large , same sized ports
the carb fitted to the manifold is spun around ( intentionally from mazda )
so that the primary ports take the long runners to the endplates
and so the secondaries take the short runners directly to the engine middle plate


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#30 Post by snocone » Sun Sep 11, 2011 11:36 am

ok so basically it is a waste of money and time in fitting a rb manifold to a hitachi carb?

The main reason for this is to keep a standard looking engine bay and drivability with the stock carb.



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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#31 Post by bumpstart » Sun Sep 11, 2011 11:51 am

yes, can't see just that manifold doing much but potentially making some of the finer things worse

best result ( if you have an r5 or a 3b motor ) will be if you tracked down the stock manifold that actually gets the runner lengths the right way around

other option may be to extrude hone your current manifold

that way you keep the stock look and functionality but may make some gains in the top end without massive drama and costs


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#32 Post by rotor_wizard » Sun Sep 11, 2011 12:17 pm

so a modded 650 Holley carb with proper fuel setup, would be the way to go.. :D


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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#33 Post by 74Rx4Wagon » Sun Sep 11, 2011 2:29 pm

if you want a better manifold for your hitachi carb then you should search out a rare manifold from the US that was fitted to some rx5 and maybe some REPU

this manifold is reversed

you read correctly
the engine fitted with this manifold originally came as 4 large , same sized ports
the carb fitted to the manifold is spun around ( intentionally from mazda )
so that the primary ports take the long runners to the endplates
and so the secondaries take the short runners directly to the engine middle plate
Could be achieved easily with a holley and RB holley manifold because they are square bore, all 4 holes are the same space from each other and from the 4 mounting posts so it would be easy to mount a holley with the primaries feeding the end plates and the secondaries feeding the centre plate. Might have to try it some time.

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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#34 Post by rotaryluvchild » Sun Sep 11, 2011 4:25 pm

74Rx4Wagon wrote:
if you want a better manifold for your hitachi carb then you should search out a rare manifold from the US that was fitted to some rx5 and maybe some REPU

this manifold is reversed

you read correctly
the engine fitted with this manifold originally came as 4 large , same sized ports
the carb fitted to the manifold is spun around ( intentionally from mazda )
so that the primary ports take the long runners to the endplates
and so the secondaries take the short runners directly to the engine middle plate
Could be achieved easily with a holley and RB holley manifold because they are square bore, all 4 holes are the same space from each other and from the 4 mounting posts so it would be easy to mount a holley with the primaries feeding the end plates and the secondaries feeding the centre plate. Might have to try it some time.

Ian.
craig has tried an original rb manifold and 650 dp holley yes car ran ok no secondaries though revving up to 7000 on primarys
didnt feel like any better accelaration and idle was good
i run a 12a with secondary bridgy and run out of fuel at the race track due to the following
1 pick up in fuel tank in series 2 rx7 - result will make a group c 80 litre tank tyo go in my series 2
now big question 10mm or just use 8mm fuel lines ??
2 float levels almost touching the roof of my nikki carby - result currently modify my carby to what onerios does have drilled jets and air tubes nicely primary - 90 air - 120 , secondary - 140 - air now at 220 .
3 replaced mazda fuel pump which gives you a static unloaded fuel run into coke bottle of 450mls
- now have carter u.s. 30 gallons model - which gives me 1700mls tested for 60 seconds
4 car does run a little better can get some racing out of it goes to half a tank and does splutter on some bends when cornering.
so after i decide to make a bigger tank with 2 pick ups for fuel at the back corners OR DO I MAKE ONE PICK UP IN MIDDLE with small box sectoin at back 50mm lower 100 to 150mm box area for fuel to fall into thus never running out , theory!!

willing to try 1 or 2 things simple and easy on my budget

anyone else having as much fun as me!!!!
and as for a holley 450 4 barrel good luck finding one under the $$450 mark
so i soon may have a first gen rb 12a manifold for sale if i can't figure this nikki carb thing
good luck fellow mazdas ........craig



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Re: Racing Beat,12a Holley Intake manifold To Nikki Caby?

#35 Post by Oneiros » Sun Sep 11, 2011 6:51 pm

rotaryluvchild wrote:
74Rx4Wagon wrote:
if you want a better manifold for your hitachi carb then you should search out a rare manifold from the US that was fitted to some rx5 and maybe some REPU

this manifold is reversed

you read correctly
the engine fitted with this manifold originally came as 4 large , same sized ports
the carb fitted to the manifold is spun around ( intentionally from mazda )
so that the primary ports take the long runners to the endplates
and so the secondaries take the short runners directly to the engine middle plate
Could be achieved easily with a holley and RB holley manifold because they are square bore, all 4 holes are the same space from each other and from the 4 mounting posts so it would be easy to mount a holley with the primaries feeding the end plates and the secondaries feeding the centre plate. Might have to try it some time.

Ian.
craig has tried an original rb manifold and 650 dp holley yes car ran ok no secondaries though revving up to 7000 on primarys
didnt feel like any better accelaration and idle was good
i run a 12a with secondary bridgy and run out of fuel at the race track due to the following
1 pick up in fuel tank in series 2 rx7 - result will make a group c 80 litre tank tyo go in my series 2
now big question 10mm or just use 8mm fuel lines ??
2 float levels almost touching the roof of my nikki carby - result currently modify my carby to what onerios does have drilled jets and air tubes nicely primary - 90 air - 120 , secondary - 140 - air now at 220 .
3 replaced mazda fuel pump which gives you a static unloaded fuel run into coke bottle of 450mls
- now have carter u.s. 30 gallons model - which gives me 1700mls tested for 60 seconds
4 car does run a little better can get some racing out of it goes to half a tank and does splutter on some bends when cornering.
so after i decide to make a bigger tank with 2 pick ups for fuel at the back corners OR DO I MAKE ONE PICK UP IN MIDDLE with small box sectoin at back 50mm lower 100 to 150mm box area for fuel to fall into thus never running out , theory!!

willing to try 1 or 2 things simple and easy on my budget

anyone else having as much fun as me!!!!
and as for a holley 450 4 barrel good luck finding one under the $$450 mark
so i soon may have a first gen rb 12a manifold for sale if i can't figure this nikki carb thing
good luck fellow mazdas ........craig
bad cornering is a common issue with the nikki due to float design... see if you can get some early style floats which are bigger, I've heard that they help.



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