2276 Build Exhaust size choice

[Jimbosmith]

Hi everyone,

Trying to workout a exhaust size for my 2276
All internals balanced and

CR is 9.6:1
FK8 cam with 1.4 rockers
48IDF carbs with port matched maniflolds
Scat Super D  42x37mm Heads
82mm counterweight cam
lightweight flywheel

No idea on BHP, yet as its still on a pallet.

My choices are between 1 5/8 and 1 3/4

Weekend Driven, but i do intend to hit the dragstrip with it, on occasions.  Transmission and axles are built strong enough for strip use.

[BugBusBuggy]

Hi Jimbo,
My engine spec is in the 'In da Works' section (68 Chinchilla beetle), I went 1 5/8 after a lot of research. I'm finishing off the installation this weekend. Again, street and strip. Broadly speaking the larger bore will move your power band further up the rev range so might be less good on the street.

If I remember, John Maher has a 190 bhp motor with a 1 5/8 (42mm) on his website.

All that said, I've not had mine dyno yet and I'm not an engine builder, but I read a LOT of articles, threads on various forums, and countless websites....

Hope this helps a bit!
Dave.

[BugBusBuggy]

I started off with this, basically where your power is made and took as a guide rather than an absolute...
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[Jimbosmith]

Thanks had seen that chart before. Will have a look at your built spec now

[UltraOrange67-2443]

I have a 2276 with a 1 5/8" header

[j-dub]

I also have a 2276 with 1 5/8 header, I built it as a street engine. Sounds like your engine above will be similar Jim so 1 5/8 would likely work well.