carburetors on a 240

[AlligatorBling]

Just out of curiosity, say I were to one day switch my motor to a carburetor set up with some really tricked out race carburetors, how much power do think I could pump out of them? ... also, I know that crabs are old technology by far, however ive heard you can get more power out of them, is this true? :confused:

[BeteNoir]

Check this (http://510.streetracing.org/gallery/data/543/2Dsc05392.jpg) out.

New carbs are far different from carbs of old. Carbs are really great for WOT performance. www.racetep.com has full race packages for monster hp from a carburetted N/A motor

[deviousKA]

Hey thats Rich's car! it will be tuned for much more hp in the future, i think he is going to put his 50mm's on there. Anyway most of the carbbed kas you will see in 510's or 1200's. Carbs can produce lots and lots of hp, if you plan on building a wicked n/a ka, carbs are the way to go (even better results that itb setup, its true). 50mm carbs can flow more than the head can accept. Most 200+hp n/a ka's are running carb setups (same guy that has that car above has 250hp ka24e). One problem is that if your doing a ka24e, the nissan motorsports intake price just shot up to 400 in the last year vs. 250 it was before. If your going with a de, you will have to fabricate your own manifold as seen above, I have done this. Instead i started with fwd head, and it is on a destroked block and sitting on my engine stand waiting for a chassis.

[Startours7]

Carbs will gave you much more power then EFI, but I wouldn't want to put them on a car a was driving everyday. Every time I take my truck to the desert I have to adjust the damb thing while I'm out there, (Holly 650 secoundery vac.)
Not a big deal because I only drive my truck for fun stuff. All play and no work make happy truck. If I worked construction and had to drive it everyday to make money it would be a pain in the ass. I don't even want to think about 4 of the stupid things.
If it's all fun your doing with the car go for it.

[Chernobyl]

Originally posted by deviousKA
if you plan on building a wicked n/a ka, carbs are the way to go (even better results that itb setup, its true).

I have a very hard time believing this. ITB > carbs any day.

[sykikchimp]

Hey Devious, how are you destroking? Gimme details on your crank!

[Jeff240sx]

Originally posted by deviousKA
Instead i started with fwd head, and it is on a destroked block and sitting on my engine stand waiting for a chassis.

There has been a lot of debate on how to destroke a KA, and the only conclusion that I've seen is to order a custom crank from a company like Crower or someone.
But the only thing I'm having a problem with is that your sig says a ka25e, which is the opposite of destroked, and poses another problem. How do you get .1 liter more? At a .040" overbore (the most you'd want to do on a ka block, you're only hitting 2.446 liters or something close, which isn't a 2.5 liter.
Just trying to figure out what you've done and how you're doing math.
-Jeff

[deviousKA]

Ok, if anyone is interested i will clarify. My destroked "ka" is actually a hybrid of l, z, and ka parts. I am utilizing a medium dk ht z20 siamesed block. the crankshaft is a balanced l20b crank stroked to 88mm. Engine bore is 90.7mm so it is almost a 2.3l. I am using a modified fwd ka24de head (decided on using this because of less modification needed to fit z timing cover). This is on an engine stand in my shop.

The 2.5l ka24e i have in my car now. Stock crankshaft, I am using the piston kit that i designed and sell. Bore is 91.1mm btw (roughly .080" over) 10.5:1 CR

L, and Z crankshaft journals can be modified to fit ka (using l or z rods) i have done it, ask me how if you are interested. This gives you the options of 86 and 92mm and stroked variants using a tall deck ht (247mm). Very long rods needed for small stroke setups in this block.

[Warwick5s]

i had a vw 16v rabbit gti with twin 40DCOE webers a few years ago. it was REEEEEEEEEEEEDICULOUS how much power that thing had, but i sold it because i wanted to get something that was still fun, but that wouldn't take 10 minutes to start in the winter, or require a rejetting every few months.


if you plan on daily driving a carbed car like this, make sure you take the extra steps to make it driveable every day like an electric choke.


having experienced 'serious' carbs, i'd take ITB's + Megasquirt ECU over carbs any day.

[drifties151]

i've been tossing the idea of building a carb'd ka for a while and im relatively new to the all motor scene after my t3 engine blew up, soooo im assuming you would definitely need a stand alone system to run a carb setup, haltec E6k for instance?
-terry

[Warwick5s]

to run an ITB system you would, but since carbs have no fuel injectors, or even any electronic components, the only thing you'd need an ECU for is ignition.


basically, you need the fuel line, a fuel pressure regulator, and the carbs, and that's it. all of the metering is done through careful tuning of the carbs jets.

[drifties151]

wow, so you could use stock ecu? or would it have to be tuned in someway? also... what sensors would you retain? awesome info here, thanks! :bow:
-terry

[allmotorKA]

You can use the stock ECU to run the ignition system while running carbs but you won’t be able to control the ignition curve any and chances are your ECU will have numerous faults due to the lack of MAF, TPS, and EGR sensors (just to name a few) which will most likely soften the ignition curve. Most people just take a distributor and oil pump shaft from an L series engine and put it on the KA24E. Best bet is to use a distributor from a ’78 and on L20B as I believe they had the electronic version with the ignitor “matchbox” on the side of the distributor instead of the earlier versions which had remote ignitor boxes or even the much earlier versions which used mechanical breaker points. You have to drill and tap the timing chain cover to mount the L series distributor but that’s about it. Then you’ll have a mechanical/vacuum advanced distributor with carbs and the KA will run old school style.

[drifties151]

does that just apply for the kaE engine or the DE too? i was thinking that b/c it is a modern ignition setup that it would have ample spark... but just incase run a Kenne Belle Boost-a-Spark type of system and tune it through that way.

[AlligatorBling]

Hmmmm.... this is a very tempting idea after reading all the replies... how much hp you think i could get out of my ka with the mods listed in my sig and a set of really nice carbs tuned right? Thanks for all the replies as well! :D

[ssssilvia]

my dad bought a 91 300zx after a pal of his blew the engine in it. he found a new block for it and then decided that he thought it would be fun to put carbs on it. so he had a friend of his build a manifold for him and used some old triple deuces of the old porsche 911's and he had 350 horsepower with built internals.