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 Post subject: Carb Questions
PostPosted: Fri Dec 03, 2010 2:09 pm 

Joined: Sun Nov 16, 2008 1:37 am
Posts: 308
Location: utah
Ok, so i am going to hold out on swapping my car to a RB, so it means i need a little more power to hold me over. I am going to do a L28 in my car, but dont know what carbs to do. DO the SU's off the 240 and 260 work for the L28 or does the extra displacement hurt the performance? Also from your experience would you do stock style SU's or Webers, those are the 2 different ones i am really thinking about. I want something that isnt to much hassle as i change altitude alot living in the mountains, as well as pretty drastic temp changes.

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Sorry if i stole anyones pictures by the way. They just do a good job of showing the 2.


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 Post subject: Re: Carb Questions
PostPosted: Fri Dec 03, 2010 4:39 pm 
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Joined: Fri Oct 12, 2007 8:57 pm
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Location: Arlington, TX, USA
skyrine wrote:
DO the SU's off the 240 and 260 work for the L28 or does the extra displacement hurt the performance?


If you have a stock cam and aren't planning to rev it over 5k much, I'm sure they'll be fine. Should be nice and torque-y. :tu:

Quote:
I want something that isnt to much hassle as i change altitude alot living in the mountains, as well as pretty drastic temp changes.


Then why not EFI? Simple, cheap, and does everything you need?

Not quite as "sexy" though... :P


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 Post subject:
PostPosted: Fri Dec 03, 2010 4:53 pm 
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Location: Sydney, Australia
As a third alternative, I think Ztherapy offer enlarged SU-style carbs, so you can keep the stock look, but will be an upgrade from the twin Hitachis, that will almost be as powerful as triples, but less finicky

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 Post subject:
PostPosted: Fri Dec 03, 2010 5:52 pm 
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Joined: Sat Feb 10, 2007 5:23 pm
Posts: 297
Location: Napa Ca
SUs will not like really big cams. They can be made to work, but it might not idle well. Webers are tough to jet since they have more adjustments than you can shake a stick at. Mikunis can also be tough to jet, however you have less things to play with to get them to run well. I'd say you want 44/45mm carbs, with likely 37mm venturis depending on the head work done and the cam you are running. From what I have found the Mikunis don't seem to be affected by weather or small changes in altitude much. (Small as in 1500 feet or so.) The last time I ran my car at altitude, I went a step smaller in the fuel jets, but I was also at nearly 7000 feet when jetted for sea level.

Remember, if you improve things on the intake side, you need to improve things on the exhaust side as well.

Will

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 Post subject:
PostPosted: Fri Dec 03, 2010 6:22 pm 

Joined: Sun Nov 16, 2008 1:37 am
Posts: 308
Location: utah
Forgive my ignorance but what do you mean on the exhaust side? I am already running a tubular header to a 2.5 straight pipe all the way out. I hope you are not telling me i need to do machine work to get a decent performance out of the 2.8 as i am mainly doing it to hold me over until a RB swap in a couple years.


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 Post subject:
PostPosted: Sat Dec 04, 2010 9:43 am 
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Joined: Sat Feb 10, 2007 5:23 pm
Posts: 297
Location: Napa Ca
skyrine wrote:
Forgive my ignorance but what do you mean on the exhaust side? I am already running a tubular header to a 2.5 straight pipe all the way out. I hope you are not telling me i need to do machine work to get a decent performance out of the 2.8 as i am mainly doing it to hold me over until a RB swap in a couple years.


I missed the fact that you already had headers and a large exhaust. I'd say you are good on the exhaust side.

If you spent the $$$$ for a well built head, you could have lots of hp if its done right.

Will

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1959 Alfa Romeo 101.02 Sprint (big project)
1969 Alfa Romeo 105.51 GTV (R.I.P)
'87 BMW M3


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