Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
California Smog test, NOX and Compression Ratio on 2L
Forum Index -> Bay Window Bus Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
SGKent Premium Member
Samba Member


Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
SGKent is offline 

PostPosted: Sat Aug 22, 2020 11:51 am    Post subject: California Smog test, NOX and Compression Ratio on 2L Reply with quote

Question for California smog bus owners with late 2L bay engines

What compression ratio are you running, what deck if you know, what are your NOX numbers on tests, and what head temps on the freeway? I am trying to determine how much bumping the C/R from 7:1 to 7.5:1 will affect NOX on the smog tests, and head temps.

For example - my bus engine has run with both 7.3:1 and 7.0:1 pistons.

7.3:1 deck .100" NOX was 621/545 and head temps were 410 F - 425 F
7.0:1 deck .100" NOX was 652/554 and head temps were 395 F - 410 F

I might add - Colin has a stock 1977 and 1978. According to his posts, he typically got an average of 410 F - to a max of 444 F head temps up a hot desert grade. The engines were stock at that time, original which would be 7.3:1 and it can be assumed that the NOX would have been within factory specs to pass smog. That kind of agrees with the 7.3:1 engine I built but his deck would have been .60" with a stock chamber volume.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
tommu
Samba Member


Joined: November 15, 2011
Posts: 616
Location: L.A.
tommu is offline 

PostPosted: Sun Aug 23, 2020 8:04 pm    Post subject: Re: California Smog test, NOX and Compression Ratio on 2L Reply with quote

I'm running 7.3.1 with a .074 deck.

After break in I was getting head temps between 390 and 415f. This was with a very lean tune to pass SMOG. 98/33 nox. This tune was so lean I was getting some stumbling when pulling away and a little bit of a lean miss at idle.

I'm running maybe a little too rich now, but it seems to be what the motor wants. it's driving very nicely. I'm peaking at 405f in the recent heatwave on long steep inclines and hanging around 485f on the flats.

I'm wondering if that 7.0.1 compression ratio was a nice way to lose some grief from owners of aging buses!
_________________
Green Bay Bus Yellow Ghia Blue Bug
Back to top
View user's profile Send private message Gallery Classifieds Feedback
SGKent Premium Member
Samba Member


Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
SGKent is offline 

PostPosted: Sun Aug 23, 2020 8:55 pm    Post subject: Re: California Smog test, NOX and Compression Ratio on 2L Reply with quote

tommu wrote:
I'm running 7.3.1 with a .074 deck.

After break in I was getting head temps between 390 and 415f. This was with a very lean tune to pass SMOG. 98/33 nox. This tune was so lean I was getting some stumbling when pulling away and a little bit of a lean miss at idle.

I'm running maybe a little too rich now, but it seems to be what the motor wants. it's driving very nicely. I'm peaking at 405f in the recent heatwave on long steep inclines and hanging around 485f on the flats.

I'm wondering if that 7.0.1 compression ratio was a nice way to lose some grief from owners of aging buses!


maybe - your numbers are really nice but I think you meant 385F not 485F Smile Nicer than mine at 7:1.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
tommu
Samba Member


Joined: November 15, 2011
Posts: 616
Location: L.A.
tommu is offline 

PostPosted: Mon Aug 24, 2020 2:35 pm    Post subject: Re: California Smog test, NOX and Compression Ratio on 2L Reply with quote

SGKent wrote:
tommu wrote:
I'm running 7.3.1 with a .074 deck.

After break in I was getting head temps between 390 and 415f. This was with a very lean tune to pass SMOG. 98/33 nox. This tune was so lean I was getting some stumbling when pulling away and a little bit of a lean miss at idle.

I'm running maybe a little too rich now, but it seems to be what the motor wants. it's driving very nicely. I'm peaking at 405f in the recent heatwave on long steep inclines and hanging around 485f on the flats.

I'm wondering if that 7.0.1 compression ratio was a nice way to lose some grief from owners of aging buses!


maybe - your numbers are really nice but I think you meant 385F not 485F Smile Nicer than mine at 7:1.


Ah yes would be a bit too much Smile
_________________
Green Bay Bus Yellow Ghia Blue Bug
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Bay Window Bus All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.