is 50mm mikuni carbs good for me?

[kcoke]

Ok So I have An L24 in my 240z stock engine but I have a performance racing cam headers and performance ignition........is triple 50mm mikunis to big for my engine? Need advice?

[jmortensen]

Too big for a street car for sure. I'd go 44's because I tend towards the more aggressive / less streetable end of the spectrum, most here will tell you to go with 40's.

[WingZr0]

What does 50's do that would make them unstreetable?

[Arne]

Basically, they flow too much air. The larger throats allow the the air to move more slowly, which hurts torque. Carb size needs to be matched to the airflow needs of the engine. Triple 50's are way too much for a mostly stock L24.

[Exdamyankee]

A little confused, you say "stock engine" and then add "racing cam" & headers. News flash, you're not "stock" anymore! Depending on the cam, and how well the head flows on your motor, I'd say the 50's are either way too big or borderline too big. Overcarburetion doesn't help performance, it hurts it. If you try to jet down the big 50's you'll most likely have abysmal part throttle and low rpm performance.

Best to match the carb size to the engine airflow, which will be a computation involving cubic displacement, peak power RPM and volumetric efficiency (VE).

For an L24 in a racing application, you could use something in the 48-50mm size, but that would be based on max power at 7000+ RPM and an engine living in the high rev zone most of the time. For flexibility for the street on an engine that will have peak power in the 5500 RPM range, 50's are major overkill.

I don't know a lot about the Mikunis, but they seem pretty similar to Webers and Dellortos. If I were sizing Webers for the car I'd probably start calculating around 40DCOEs with 35mm chokes.

There's what looks to be a nice set of Mikuni 40's on eBay right now (no, I have no financial interst in them):

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=004&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=140125706942&rd=1,1

[240ZGL]

Ya, 50's are way too big for the street. You won't have anything to work with till you get up around 5000 rpm. I'm doing a L24 with flat tops, stage 1 cam, head work and large valves, exhaust, and triple 40's. Should make for a good street motor on the weekends. 50's would blow the whole package.

[red_dog007]

I wish that I had had the money for those atm.

What if you had a diesel stroke with everything slightly bored, and larger intake/exhaust ports. How would 50mm triple carbs be then? This is what I am ultimately wanting to do with my L24.

[240ZGL]

Then you end up with a 260 maybe a 270 if you push it. If you have to have 50's on the street, you should look at doing a 3.1. It cost a lot more to build a motor to fit the carbs than it would to by carbs to fit your motor.

[Exdamyankee]

Concur with 240ZGL. A 3.1 stroker can run 50s. A stroked L24 still won't have more than the displacement of a stock L28, and the biggest thing I would put on an L28 for normal street use would probably be 45's, with 38mm chokes.

3.1 strokers are expensive motors! Go with 40's if you want trips on your L24, kcoke.

[gnosez]

I'm running 44mm Mikunis on my 3.2L and the only reason I'd run 50s would be if I made it into a track-only car.

[jmortensen]

I'm running 44mm Mikunis on my 3.2L and the only reason I'd run 50s would be if I made it into a track-only car.

I agree. Where's Mark Belrose when you need him??? He's running 50s on his race car with a stroker motor. I think last week he said on a different forum that power comes on at 5000 rpms. That right there should tell you what you need to know.