Ok.. I know this is a bit of a rehash.. But generally, not rally specific. What would you prefer and why? The way I see it: Weber DCOEs + Generally agreed to be the best carburator out there + No Electronics - It's a carburator.. they are finicky by nature.. sure you can get it good enough - They're not exactly cheap, and all the tuning bits and bobs aren't free! Throttle Bodies with DCOE pattern: + Least amount of f'in about for good fuel injection - Expensive as F Adapted Bike Throttle Bodies + Cheapest way to get ITBS that I know of - The most f'in about Am I missing something? Does anyone know of a Cheap supplier for DCOE patterned ITBs? They're pretty flipping simple to make.. there's obviously a LOT of mark up in TWMs price. I know of Jenvey and Extrudabody. Cheers, Andrew https://www.rallyanarchy.com/phorum/read.php?1,26036,26036#msg-26036 Sat, 04 Apr 2026 14:35:55 -0500 Phorum 5.2.15a https://www.rallyanarchy.com/phorum/read.php?1,26036,26655#msg-26655 https://www.rallyanarchy.com/phorum/read.php?1,26036,26655#msg-26655 Dazed_Driver Rally Chat Sun, 26 Apr 2009 18:04:42 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26654#msg-26654 https://www.rallyanarchy.com/phorum/read.php?1,26036,26654#msg-26654 -------------------------------------------------------
> Yeah, that is true. I'm still debating on whether
> I want to deal with making a manifold, or if I
> just want to give in and buy a 20v ITB setup...
> which is ridiculous amounts of money for what you
> get.

Buy a full 20V with the ITBs then sell off the engine and keep the ITBs. Seems they're not all that much on ebay.]]> NoCoast Rally Chat Sun, 26 Apr 2009 17:45:19 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26652#msg-26652 https://www.rallyanarchy.com/phorum/read.php?1,26036,26652#msg-26652 -------------------------------------------------------
> Sorry - I threw bike carbs in as a potential cheap
> and easy mod for guys running small displacement
> motors like your NSU...
>
> Going with the bike ITB's with programable FI is
> definitely better in the end no doubt - but bang
> for the buck using bike carbs would be pretty darn
> high.
>
> But my scenario only works well for small
> displacement car motors. Bigger engines with bike
> carbs would be a bugger to tune, and bike ITB's
> would be the best way to go I'd think.
>
> Rabin

I got that Rabin. It's just that the car is coming with dual carbs and there's a DCOE intake manifold available. So if I wanted to go carbs.. I'd likely go the 40 DCOE route as they seem to be by far the most common size, rightly sized for a 1litre banger, and pretty cheap.. but if I were to do anything, it seems going fuel injection is the best route. Maybe I'm wrong with that. I have certainly heard good things about bike and snowmobile carbs as development didn't end 40+ years ago!

]]> hudson Rally Chat Sun, 26 Apr 2009 15:38:27 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26651#msg-26651 https://www.rallyanarchy.com/phorum/read.php?1,26036,26651#msg-26651
Going with the bike ITB's with programable FI is definitely better in the end no doubt - but bang for the buck using bike carbs would be pretty darn high.

But my scenario only works well for small displacement car motors. Bigger engines with bike carbs would be a bugger to tune, and bike ITB's would be the best way to go I'd think.

Rabin]]> bean Rally Chat Sun, 26 Apr 2009 15:19:02 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26650#msg-26650 https://www.rallyanarchy.com/phorum/read.php?1,26036,26650#msg-26650 Dazed_Driver Rally Chat Sun, 26 Apr 2009 14:39:31 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26649#msg-26649 https://www.rallyanarchy.com/phorum/read.php?1,26036,26649#msg-26649 -------------------------------------------------------
> For ITB's it's much easier to tune, since it
> implies that you some sort of programmable engine
> management solution available (or you at least
> should have :-)).
>
> So you really only need to find ITB's with an ID
> that suit the sort of peak power you are looking
> for. There's a lot of info on this from
> manufactureres of ITB's, etc. - but it's also not
> far off to just compare the peak power pr.
> cylinder for the bike.
>
> Displacement means nothing in that case, since you
> have 100% absolute tuneability from you EFI, thus
> stuff like engine characteristics and power band
> for the donor engine is irrelevant.

I'm not sure how the conversation got onto carbs.. but it did.

Still with the bike ITBs you still have to fab / cut an intake manifold and then get the spacing & linkage right then figure out how your going to connect them to the intake.. seems like 99% of the time that's accomplished with hose.

Changing the injectors may also be required.

Not a ridiculous amount of work, but still a fair amount.]]> hudson Rally Chat Sun, 26 Apr 2009 14:31:41 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26642#msg-26642 https://www.rallyanarchy.com/phorum/read.php?1,26036,26642#msg-26642 Dazed_Driver Rally Chat Sun, 26 Apr 2009 02:40:38 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26639#msg-26639 https://www.rallyanarchy.com/phorum/read.php?1,26036,26639#msg-26639 -------------------------------------------------------
> So all of this bike carb talk with the jetting and
> relative engine displacement, does this all come
> into effect with ITB's from bikes? Because then
> you would have the bikes displacement, the
> receiving engine's displacement, and the bike ITB
> diameter.

For ITB's it's much easier to tune, since it implies that you some sort of programmable engine management solution available (or you at least should have :-)).

So you really only need to find ITB's with an ID that suit the sort of peak power you are looking for. There's a lot of info on this from manufactureres of ITB's, etc. - but it's also not far off to just compare the peak power pr. cylinder for the bike.

Displacement means nothing in that case, since you have 100% absolute tuneability from you EFI, thus stuff like engine characteristics and power band for the donor engine is irrelevant.]]> wildert Rally Chat Sun, 26 Apr 2009 01:47:13 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26638#msg-26638 https://www.rallyanarchy.com/phorum/read.php?1,26036,26638#msg-26638
]]> Dazed_Driver Rally Chat Sun, 26 Apr 2009 01:36:15 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26362#msg-26362 https://www.rallyanarchy.com/phorum/read.php?1,26036,26362#msg-26362 -------------------------------------------------------
> You're absolutely right - I never caught that
> point :-).
>
> What I was trying to prove, was that if you trying
> to make 170 horsies on a 1800 cc engine, then
> throttle bodies (or carbs) from a 1300 cc bike
> producing 170 horsies are just fine.
>
> Two completely different points we are trying to
> make :-).
>
> I do have one beef with your point though. From a
> jetting point of view, it makes sense.
> But you do suffer from an overly large bore on the
> carb or throttle body though. This could easily
> hurt low end driveability, and thus also torque.
>
> Going for carbs or TB's from a 70 peak horsepower
> bike would be better for driveability. I'd even
> venture the guess that the power characteristics
> would be more similar.
>
> Brgrds
> Brian
>
>

Yep - Ideally you're correct, but getting those carbs to idle worth a damn with twice the air coming through them is a BITCH. Idle jet sizing and needle settings all have to be done basically by trial and error. Once you figure idle, then you gotta make sure there's no nasty flat spot when you transition to the main jets. It's possible for sure - just a bitch.

As a point of interest - I met Jay - the owner of a dyno shop in Colorado in 04' that said bigger carbs are always better - you just need to know how to tune them. (He's a carb GOD!) http://www.thecarburetorshop.net/bigger1.html

So with proper tuning you might do really well with the 140 HP carbs on a 70n HP motor. Out of the box and getting it running ASAP I think a lot less fiddling would need to be done with my scenario.

Rabin]]> bean Rally Chat Wed, 22 Apr 2009 00:49:43 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26208#msg-26208 https://www.rallyanarchy.com/phorum/read.php?1,26036,26208#msg-26208
What I was trying to prove, was that if you trying to make 170 horsies on a 1800 cc engine, then throttle bodies (or carbs) from a 1300 cc bike producing 170 horsies are just fine.

Two completely different points we are trying to make :-).

I do have one beef with your point though. From a jetting point of view, it makes sense.
But you do suffer from an overly large bore on the carb or throttle body though. This could easily hurt low end driveability, and thus also torque.

Going for carbs or TB's from a 70 peak horsepower bike would be better for driveability. I'd even venture the guess that the power characteristics would be more similar.]]> wildert Rally Chat Mon, 20 Apr 2009 16:34:31 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26194#msg-26194 https://www.rallyanarchy.com/phorum/read.php?1,26036,26194#msg-26194 -------------------------------------------------------
>
> I don't know how to put it nicely - other than:
> You got it wrong :-).
> RPM has nothing to do with how much diameter you
> need for X amount of horsepower.
> 1 HP is 1 HP is 1 HP, and it requires the exact
> same amount of air and fuel, regardless of how
> many RPM it takes to develop that 1 HP.
>
> HP is a product of torque and number of
> repetitions over time (the RPM's).
> This is simplified a bit, but it is still valid:
> If you make 1 HP from X amount of torque being
> repeated 10 times in one second (10 revs pr.
> second), or you make it by 10 times X amount of
> torque being repeated once in one second (1 rev
> pr. second) - it's still 1 HP, and it still
> requires the exact same amount of air and fuel pr.
> second to enter the engine.
>
> So you only need to look at peak horsepower, when
> trying to figure out when increasing the ID of the
> carb or TB, will cross the point of diminishing
> returns (maybe even the point where you'll hurt
> performance due to low air speeds).
>
> Look at ads for performance carbs for those big
> V8's you guys have over on your side of the pond.
> They're all quoted for x amount of CFM (cubic feet
> per minute) that they can flow. Thus a 600 cfm
> carb will fit equally well on a slow reving big
> block, and a faster small block, provided that
> they develop about the same amount of horsies.
>
> Brgrds
> Brian
>
>

I think you're mis-understanding my point. I agree with everything you've said, but it has nothing to do with what my point is.

My point:

My ZX-10 (1000cc) makes 130 HP at 11000 RPM. At 6000 rpm it's making 70 HP. If the carbs are tuned great, I can unbolt them and put them on a 70 HP 1000cc Austin Mini motor and have very little tuning to do to get them dialed in.

* Power numbers quoted are just to illustrate a point.

I made no claims as to the HP potential of the carbs, but tuning wise they have the same air flowing through at idle all the way to 6000 rpm - so getting them to work on the Mini should be easy.

So my only point was ease of tuning bike carbs on a car motor for cheap bang for the buck results.



Rabin

]]> bean Rally Chat Mon, 20 Apr 2009 12:27:36 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26150#msg-26150 https://www.rallyanarchy.com/phorum/read.php?1,26036,26150#msg-26150 -------------------------------------------------------
> Have a look at this link to the VW Vortex. It is
> an inventory of all bike carbs and ITBs.
>
> Robert.

Blows my mind that there's so many different ones. oy!]]> hudson Rally Chat Sat, 18 Apr 2009 22:22:48 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26143#msg-26143 https://www.rallyanarchy.com/phorum/read.php?1,26036,26143#msg-26143 -------------------------------------------------------
> That is a good point, but your numbers need to get
> scaled down because of RPM. Also - a lot of the
> big numbers you're talking about are mostly
> injected bikes. Numbers come down a bit for
> production bikes on carbs, and when you factor in
> the RPM peak of 6-7000 RPM of the NSU (if that?)
> the power numbers are MUCH closer than the peak
> numbers you posted.
>
> So while there is a crap load of variables - it'd
> still be easier to tune if the carbs came off a
> big engine of similar displacement to the NSU.
> While they're capable of flowing for 10 - 11000
> rpm - the little NSU will never see that, They're
> still capable of proper fueling right through to
> that range so it shouldn't be too hard to set up.

I don't know how to put it nicely - other than: You got it wrong :-).
RPM has nothing to do with how much diameter you need for X amount of horsepower.
1 HP is 1 HP is 1 HP, and it requires the exact same amount of air and fuel, regardless of how many RPM it takes to develop that 1 HP.

HP is a product of torque and number of repetitions over time (the RPM's).
This is simplified a bit, but it is still valid:
If you make 1 HP from X amount of torque being repeated 10 times in one second (10 revs pr. second), or you make it by 10 times X amount of torque being repeated once in one second (1 rev pr. second) - it's still 1 HP, and it still requires the exact same amount of air and fuel pr. second to enter the engine.

So you only need to look at peak horsepower, when trying to figure out when increasing the ID of the carb or TB, will cross the point of diminishing returns (maybe even the point where you'll hurt performance due to low air speeds).

Look at ads for performance carbs for those big V8's you guys have over on your side of the pond. They're all quoted for x amount of CFM (cubic feet per minute) that they can flow. Thus a 600 cfm carb will fit equally well on a slow reving big block, and a faster small block, provided that they develop about the same amount of horsies.]]> wildert Rally Chat Sat, 18 Apr 2009 08:03:17 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26129#msg-26129 https://www.rallyanarchy.com/phorum/read.php?1,26036,26129#msg-26129 -------------------------------------------------------
> For idle, displacement may be of some concern. But
> when it comes to the actual sizing of the TB, then
> it's more important to compare power of the
> engines.
> The ID of the TB is basically what limits the
> amount of HP the TB will flow air for.
> With big bike engines producing 160-170 hp or more
> on a 4 cyl, we are seing +60 hp pr. cylinder.
> This is what should be compared when choosing a
> bike TB or carb for at car.
>
> Brgrds
> Brian

That is a good point, but your numbers need to get scaled down because of RPM. Also - a lot of the big numbers you're talking about are mostly injected bikes. Numbers come down a bit for production bikes on carbs, and when you factor in the RPM peak of 6-7000 RPM of the NSU (if that?) the power numbers are MUCH closer than the peak numbers you posted.

So while there is a crap load of variables - it'd still be easier to tune if the carbs came off a big engine of similar displacement to the NSU. While they're capable of flowing for 10 - 11000 rpm - the little NSU will never see that, They're still capable of proper fueling right through to that range so it shouldn't be too hard to set up.

Rabin


]]> bean Rally Chat Fri, 17 Apr 2009 11:55:45 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26128#msg-26128 https://www.rallyanarchy.com/phorum/read.php?1,26036,26128#msg-26128
I've picked up 40 DCOE's from ebay for as little as $15 (usually missing jets and whatnot). Only thing remaining is to decide where to run the injectors...intake or TB. Or even the 'above the airhorn' Extrudabody setup.

Bob]]> Ascona73 Rally Chat Fri, 17 Apr 2009 11:46:59 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26127#msg-26127 https://www.rallyanarchy.com/phorum/read.php?1,26036,26127#msg-26127

And of course that would be even more interesting if we knew bore center to center on some of the likely candidates like all those Faule Vays.]]> john vanlandingham Rally Chat Fri, 17 Apr 2009 11:35:33 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26126#msg-26126 https://www.rallyanarchy.com/phorum/read.php?1,26036,26126#msg-26126 http://forums.vwvortex.com/zerothread?id=2838896

Robert.]]> Rallymech Rally Chat Fri, 17 Apr 2009 11:14:30 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26119#msg-26119 https://www.rallyanarchy.com/phorum/read.php?1,26036,26119#msg-26119
It may take a bit to get the jetting right but having driven the 2.3 Ford buggy they work and with places like Bent Bike salvage yards it isn't totally unreasonable to get an affordable set-up.]]> heymagic Rally Chat Fri, 17 Apr 2009 01:45:23 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26118#msg-26118 https://www.rallyanarchy.com/phorum/read.php?1,26036,26118#msg-26118 -------------------------------------------------------
> So in cases where you're fitting them on a car
> motor of similar displacment as the donor bike - I
> think it's definitely worth a try as it'd be great
> bang for the buck if they dialed in easy.

For idle, displacement may be of some concern. But when it comes to the actual sizing of the TB, then it's more important to compare power of the engines.
The ID of the TB is basically what limits the amount of HP the TB will flow air for.
With big bike engines producing 160-170 hp or more on a 4 cyl, we are seing +60 hp pr. cylinder.
This is what should be compared when choosing a bike TB or carb for at car.]]> wildert Rally Chat Fri, 17 Apr 2009 00:57:51 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26113#msg-26113 https://www.rallyanarchy.com/phorum/read.php?1,26036,26113#msg-26113
On your NSU however - the displacement is much closer to that of a liter bike, so you should have very little tuning in order to have a pretty sweet set up.

So in cases where you're fitting them on a car motor of similar displacment as the donor bike - I think it's definitely worth a try as it'd be great bang for the buck if they dialed in easy.

Something to be wary of buying used carbs is there's no garantee the carbs were working on the bike to begin with, so if you can start with known good carbs that's a big plus.

Rabin

]]> bean Rally Chat Fri, 17 Apr 2009 00:10:42 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26106#msg-26106 https://www.rallyanarchy.com/phorum/read.php?1,26036,26106#msg-26106 -------------------------------------------------------
> heymagic Wrote:
> --------------------------------------------------
> -----
> > I worked on a sand rail last year with a
> pro-built
> > 2.3 Ford. It had 4 Mikunis off of some bike.
> They
> > were mounted with rubber hose to a home made
> > intake, stub pipes on a flange. Started
> easily and
> > ran like a scalded dog.
>
> That's the Esslinger Racing Mikuni set-up. The
> Mikunis are off some snowmobile application.
>

It's been a while and my memory is not so good but that looks about right.
]]> heymagic Rally Chat Thu, 16 Apr 2009 21:27:38 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26093#msg-26093 https://www.rallyanarchy.com/phorum/read.php?1,26036,26093#msg-26093
www.jenvey.com

They work out cheaper to Canada anyways.]]> hudson Rally Chat Thu, 16 Apr 2009 19:02:55 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26092#msg-26092 https://www.rallyanarchy.com/phorum/read.php?1,26036,26092#msg-26092 Dazed_Driver Rally Chat Thu, 16 Apr 2009 18:59:17 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26090#msg-26090 https://www.rallyanarchy.com/phorum/read.php?1,26036,26090#msg-26090
Twin Bodies DCOE short 30mm REF.
PRICE
Twin body 40mm STB40 360€


Twin body 45mm STB45 360€
Twin body 48mm STB48 360€

Twin body pair 40mm STB40P 645€
Twin body pair 45mm STB45P 645€
Twin body pair 48mm STB48P 645€
Twin body pair 50mm STB50P 660€
Twin Bodies DCOE long 91mm REF. PRICE
Twin body 40/42/45/48mm THS? 375€
Twin body 50/52/55mm THS? 395€

Twin body pair 40/42/45/48mm THP? 675€
Twin body pair 50/52/55mm THP? 715€

That's all with DCOE bodies.
If you can divorce yourself from DCOE then there are modular single bodies for starting at 120 Euro

Chadil.be

Twin Bodies DCOE long 118mm REF. PRICE
Twin body 40/42/45mm TBS? 375€
Twin body 48/50mm TBS? 395€

Twin body pair 40/42/45mm TBP? 675€
Twin body pair 48/50mm TBP? 715€]]> john vanlandingham Rally Chat Thu, 16 Apr 2009 17:35:55 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26089#msg-26089 https://www.rallyanarchy.com/phorum/read.php?1,26036,26089#msg-26089 Carl S Rally Chat Thu, 16 Apr 2009 17:35:46 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26078#msg-26078 https://www.rallyanarchy.com/phorum/read.php?1,26036,26078#msg-26078 -------------------------------------------------------
> I worked on a sand rail last year with a pro-built
> 2.3 Ford. It had 4 Mikunis off of some bike. They
> were mounted with rubber hose to a home made
> intake, stub pipes on a flange. Started easily and
> ran like a scalded dog.

That's the Esslinger Racing Mikuni set-up. The Mikunis are off some snowmobile application. http://www.esslingeracing.com/catalog/page16.pdf
]]> noypiesky Rally Chat Thu, 16 Apr 2009 13:42:09 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26074#msg-26074 https://www.rallyanarchy.com/phorum/read.php?1,26036,26074#msg-26074
Not 100% sure but I think the discussion involved Charlie North from First Function Motorsport.

Perhaps give him a shout, he seems very knowledgable :

http://www.ffmsd.com/]]> Morten2 Rally Chat Thu, 16 Apr 2009 12:53:38 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26058#msg-26058 https://www.rallyanarchy.com/phorum/read.php?1,26036,26058#msg-26058
I would add one extra con though: Bike TB's mounted with rubber hose to stubs on manifold, are not the most flow friendly thing in the world. You need to get it JUST right.

For me, DCOE TB's aren't worth the cost - but then: I'm a cheap bastard.
I haven't gone any of those routes though - I have a set of Toyota Corolla 20V TB's on my Golf. They are flange mounted, so I had to fab up a manifold - big hassle... but that was just about the tinkering and mucking about that I had with it.]]> wildert Rally Chat Thu, 16 Apr 2009 00:57:18 -0500 https://www.rallyanarchy.com/phorum/read.php?1,26036,26055#msg-26055 https://www.rallyanarchy.com/phorum/read.php?1,26036,26055#msg-26055 heymagic Rally Chat Thu, 16 Apr 2009 00:05:25 -0500