66 300 HP auto optional exhaust

[Russ S.]

Can anyone tell me for certain whether or not N11 off road exhaust was an available option on a 66 300 HP auto?

[Joe L.]

Re: 66 300 HP auto optional exhaust

Can anyone tell me for certain whether or not N11 off road exhaust was an available option on a 66 300 HP auto?

Russ------



GM says that N-11 was only available with manual transmission.

[Duke W.]

Re: 66 300 HP auto optional exhaust

All C2 250 HP and 300 HP/PG had 2" exhaust pipes. N11 was 2.5", so it would only couple to the front pipes of the other engine/transmission combinations that had 2.5" head pipes.

I don't think you can install 2.5" systems on PG due to interference with the transmission.

Duke

[Joe L.]

Re: 66 300 HP auto optional exhaust

All C2 250 HP and 300 HP/PG had 2" exhaust pipes. N11 was 2.5", so it would only couple to the front pipes of the other engine/transmission combinations that had 2.5" head pipes.

I don't think you can install 2.5" systems on PG due to interference with the transmission.

Duke

Duke-----


For 1966 all Corvette small blocks used 2" outlet exhaust manifolds regardless of horsepower or transmission. However, for one reason or another GM chose to not make the N-11 system available with Powerglide. As far as I know, this applied to both big blocks and small blocks.

[Russ S.]

Re: 66 300 HP auto optional exhaust

Thanks guys. Very interesting that as Joe states even the big block with auto didn't come with the n11 option but side exhaust was available.

[Duke W.]

Re: 66 300 HP auto optional exhaust

Duke-----


For 1966 all Corvette small blocks used 2" outlet exhaust manifolds regardless of horsepower or transmission. However, for one reason or another GM chose to not make the N-11 system available with Powerglide. As far as I know, this applied to both big blocks and small blocks.

Yes, but the head pipes for 300HP/MT and 350 HP were 2.5" with 2" adapters welded on to fit the 2" manifolds. N11 was the 2.5" rear section pipe/muffler assembly, only. The front section for N11 was the same as base exhaust and is 2.5" at the center joint between the front and rear sections.

Duke

[Russ S.]

Re: 66 300 HP auto optional exhaust

Yes, but the head pipes for 300HP/MT and 350 HP were 2.5" with 2" adapters welded on to fit the 2" manifolds. N11 was the 2.5" rear section pipe/muffler assembly, only. The front section for N11 was the same as base exhaust and is 2.5" at the center joint between the front and rear sections.

Duke

Duke, So are you thinking that N11 was available with 300 auto?

[Jeff S.]

Re: 66 300 HP auto optional exhaust

Russ

The GM engineering/spec package literature for '66 model year reads as follows (page 14, options & accessories section):

EXHAUST SYSTEM - OFF ROAD SERVICE. Available with any optional engine with 4 speed transmission ........... N11

BTW, I attempted to install a service replacement/counter purchased N11 system on a '66 base engine p/glide car back in ancient times. There was interference on the passenger side between the header pipe and the transmission pan area. It can be solved by having a custom bent pipe made, it seems. If I recall correctly, the welded tailpipe/muffler assembly was double wall pipe -- I'm not sure about the header pipe.

[Russ S.]

Re: 66 300 HP auto optional exhaust

Jeff, Thank you. That sheds additional light on the subject. I appreciate all your responses. That's not what I wanted to hear but is what I suspected.I like it correct, but who wants to put a puny 2 inch exhaust on their car even if it is an auto?

[Duke W.]

Re: 66 300 HP auto optional exhaust

Duke, So are you thinking that N11 was available with 300 auto?

No, 300 HP/PG used 2" pipes from the exhaust manifold to the center joint,and the rear section is also 2". The N11 rear section is 2.5" and is designed to connect to a 2.5" front section, so that's why it was limited to 300HP/MT and 350HP for small blocks, both of which used 2.5" front sections with welded on 2" adapters to connect to the 2" manifolds beginning in '66.

From '62 to '65 all 300HP/MT and all higher power SB engines used 2.5" manifolds and 2.5" head pipes all the way from the manifold connection to the center connection.

Duke

[John H.]

Re: 66 300 HP auto optional exhaust

Russ

The GM engineering/spec package literature for '66 model year reads as follows (page 14, options & accessories section):

EXHAUST SYSTEM - OFF ROAD SERVICE. Available with any optional engine with 4 speed transmission ........... N11

Jeff -

That implies that N11 wasn't available with the base (300hp) engine in '66, although the '66 JG just says it was limited to manual transmissions only without mentioning any engines.

The Chevrolet information in the '67 Engineering/spec package only says with manual transmissions, which implies that it was available with the base (300hp) engine in 1967.

N11 isn't addressed in the exhaust section of the AMA Submission, as it's an option.

Does anyone have any other Chevrolet-published information that can shed more light on the availability of N11 in '66 and '67 with small-block engines?

[Joe L.]

Re: 66 300 HP auto optional exhaust

Jeff -

That implies that N11 wasn't available with the base (300hp) engine in '66, although the '66 JG just says it was limited to manual transmissions only without mentioning any engines.

The Chevrolet information in the '67 Engineering/spec package only says with manual transmissions, which implies that it was available with the base (300hp) engine in 1967.

N11 isn't addressed in the exhaust section of the AMA Submission, as it's an option.

Does anyone have any other Chevrolet-published information that can shed more light on the availability of N11 in '66 and '67 with small-block engines?

John-----


The 1966 Chevrolet Order Guide says regarding RPO N-11:

"Off-Road Service----available only when 3 or 4 speed manual transmission is ordered"

[John H.]

Re: 66 300 HP auto optional exhaust

John-----


The 1966 Chevrolet Order Guide says regarding RPO N-11:

"Off-Road Service----available only when 3 or 4 speed manual transmission is ordered"

Joe -

Thanks - that would imply that N-11 was available with both the 300hp and 350hp engines, in 1966 and 1967, only with manual transmissions.

I have the '67 order guide, but don't have the '66 order guide.