BBC output overview.

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Locked
user-17438

Re: BBC output overview.

Post by user-17438 » Sun Sep 30, 2018 10:27 am

David Vizard wrote:
Sun Sep 30, 2018 7:59 am
MTENGINES wrote:
Sun Sep 30, 2018 3:13 am
David Vizard wrote:
Sat Sep 29, 2018 12:09 pm
OK you head porters out there. I have just been playing with an
Edelbrock big port head (started life at about 355-365 cc) I have ported one of each port looking only at the airflow gains with the intent to get the most that is practically possible. At this moment in time I have 452 cfm on the good port and 433 on the bad port at 1.150 valve lift. Good port vol is 384 cc and the bad 380 cc.
Valve is still 2.3.

Any comments on this before I throw in my $2 worth of thoughts?


DV


What head?

Don't have a part # - Edelbrock is still trying to identify a match would you believe!
Anyway here are some shots that might help.
DV
That's the Victor 24 casting. I have lots of flow data for different sizes of that casting. 345cc - 390cc. Fun head to work on. Stupid fast if you want. Lol

2.400/1.850 0work on the seats. Otherwise your throat will be huge on the exhaust if you go smaller.

David Vizard
Guru
Guru
Posts: 1437
Joined: Thu Jan 15, 2015 12:19 pm

Re: BBC output overview.

Post by David Vizard » Sun Sep 30, 2018 11:17 am

MTENGINES wrote:
Sun Sep 30, 2018 10:27 am
David Vizard wrote:
Sun Sep 30, 2018 7:59 am
MTENGINES wrote:
Sun Sep 30, 2018 3:13 am




What head?

Don't have a part # - Edelbrock is still trying to identify a match would you believe!
Anyway here are some shots that might help.
DV
That's the Victor 24 casting. I have lots of flow data for different sizes of that casting. 345cc - 390cc. Fun head to work on. Stupid fast if you want. Lol

2.400/1.850 0work on the seats. Otherwise your throat will be huge on the exhaust if you go smaller.
MT,
How about some flow numbers and port vols that achieved such.

Did the 2.4 inch intake get tangled with the 1.85 valves too early to use a lot of overlap?
Thanks
DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

gowest
Member
Member
Posts: 91
Joined: Tue Sep 04, 2007 12:43 pm

Re: BBC output overview.

Post by gowest » Sun Sep 30, 2018 1:25 pm

Hope your recovery goes well David. Would be nice if aftermarket parts worked as well for us as it does engines !
Are you still planning to make Race Engine Challenge ? Time is getting pretty thin.

David Vizard
Guru
Guru
Posts: 1437
Joined: Thu Jan 15, 2015 12:19 pm

Re: BBC output overview.

Post by David Vizard » Sun Sep 30, 2018 1:29 pm

gowest wrote:
Sun Sep 30, 2018 1:25 pm
Hope your recovery goes well David. Would be nice if aftermarket parts worked as well for us as it does engines !
Are you still planning to make Race Engine Challenge ? Time is getting pretty thin.
Thanks for your kind wishes. AS for the REC I covered my position on that in the initial post.
Thanks
DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

jed
Expert
Expert
Posts: 563
Joined: Tue Nov 18, 2008 4:18 pm
Location: Dallas

Re: BBC output overview.

Post by jed » Sun Sep 30, 2018 3:44 pm

RevTheory wrote:
Fri Sep 28, 2018 12:29 pm
There's some pretty interesting work in the chamber as well. I like it :wink:
Yes very interesting chamber. Resembles a soft head (maybe maybe not). Could you show us the piston top please.

Erland Cox
Guru
Guru
Posts: 3300
Joined: Sun Jan 29, 2006 9:46 pm
Location: Lund in Sweden
Contact:

Re: BBC output overview.

Post by Erland Cox » Sun Sep 30, 2018 5:48 pm

David Vizard wrote:
Fri Sep 28, 2018 9:42 pm
Erland,

Here is a graph of the curtain area per cube displacement. 2.62 only beats out the 2.02 in the 350 above .25 D. At all other points below the .25 D for the 2.02 it is exactly equivalent.


DV
David, a big block has 1,7 rockers to lift its valves faster because it is a bigger engine.
You must compare real valve lift curves.
If a 2,02 valve lifts ,500" a 2,3" valve must lift 0,570".
Then the 2,3 valve gets a 30% greater curtain area equialent to the displacement difference.
If a small block har ,500" lift / 1,5 X 1,7 = ,567"

Erland

Erland Cox
Guru
Guru
Posts: 3300
Joined: Sun Jan 29, 2006 9:46 pm
Location: Lund in Sweden
Contact:

Re: BBC output overview.

Post by Erland Cox » Sun Sep 30, 2018 6:58 pm

David Vizard wrote:
Sat Sep 29, 2018 12:09 pm
OK you head porters out there. I have just been playing with an
Edelbrock big port head (started life at about 355-365 cc) I have ported one of each port looking only at the airflow gains with the intent to get the most that is practically possible. At this moment in time I have 452 cfm on the good port and 433 on the bad port at 1.150 valve lift. Good port vol is 384 cc and the bad 380 cc.
Valve is still 2.3.

Any comments on this before I throw in my $2 worth of thoughts?

DV
Fantastic flow for a 4,25" bore.
2,3" intake valve seems big to me for that bore and 2,4" will probably hit the cylinder wall.

Erland

David Vizard
Guru
Guru
Posts: 1437
Joined: Thu Jan 15, 2015 12:19 pm

Re: BBC output overview.

Post by David Vizard » Mon Oct 01, 2018 8:45 am

Erland Cox wrote:
Sun Sep 30, 2018 6:58 pm
David Vizard wrote:
Sat Sep 29, 2018 12:09 pm
OK you head porters out there. I have just been playing with an
Edelbrock big port head (started life at about 355-365 cc) I have ported one of each port looking only at the airflow gains with the intent to get the most that is practically possible. At this moment in time I have 452 cfm on the good port and 433 on the bad port at 1.150 valve lift. Good port vol is 384 cc and the bad 380 cc.
Valve is still 2.3.

Any comments on this before I throw in my $2 worth of thoughts?

DV
Fantastic flow for a 4,25" bore.
2,3" intake valve seems big to me for that bore and 2,4" will probably hit the cylinder wall.

Erland
Erland,
This was on a 4.5 inch bore.

DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

David Vizard
Guru
Guru
Posts: 1437
Joined: Thu Jan 15, 2015 12:19 pm

Re: BBC output overview.

Post by David Vizard » Tue Oct 02, 2018 11:53 pm

Erland Cox wrote:
Sun Sep 30, 2018 6:58 pm
David Vizard wrote:
Sat Sep 29, 2018 12:09 pm
OK you head porters out there. I have just been playing with an
Edelbrock big port head (started life at about 355-365 cc) I have ported one of each port looking only at the airflow gains with the intent to get the most that is practically possible. At this moment in time I have 452 cfm on the good port and 433 on the bad port at 1.150 valve lift. Good port vol is 384 cc and the bad 380 cc.
Valve is still 2.3.

Any comments on this before I throw in my $2 worth of thoughts?

DV
Fantastic flow for a 4,25" bore.
2,3" intake valve seems big to me for that bore and 2,4" will probably hit the cylinder wall.

Erland
Erland - it was a 4.530 bore.

DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

David Vizard
Guru
Guru
Posts: 1437
Joined: Thu Jan 15, 2015 12:19 pm

Re: BBC output overview.

Post by David Vizard » Wed Oct 03, 2018 12:09 am

Back to same flow figs and port comparisons.

At the end of this post you will see the flow of the weird shape port Vs the rectangle port of the big port Edelbrock head. These are 322 and 382 cc respectively.
The thin graph lines are the Big port Edelbrock head (blue intake and red ex) The thick lines are the 322 cc weird port. The tests shown here go tyo 1 inch lift and at this point there was little difference in total flow of either head. However above 1 inch the Edelbrock heads port kept increasing flow up to 452 cfm at 1.150.
On the other hand the 322 cc weird port topped out at the 1 inch point and still only flowed 433 at 1.150.

Based on just the flow figures these two heads don't look that much different in the up to 1 inch lift range.
Sure the exotic port is better in the 500 to 800 lift range but though significant it's not a super deal.

Take a look at the graph and then we will move on into that territory that encompasses the (incorrect) term ' a flow bench can only tell you so much'

I am going to show that such a statement is only dependent on how well you can read!!

DV
You do not have the required permissions to view the files attached to this post.
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

David Vizard
Guru
Guru
Posts: 1437
Joined: Thu Jan 15, 2015 12:19 pm

Re: BBC output overview.

Post by David Vizard » Wed Oct 03, 2018 12:10 am

Headguy wrote:
Tue Oct 02, 2018 11:58 pm
Whatcha selling?
At the moment I am dispensing a free cure for ignorance!
DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

408 Nova
Member
Member
Posts: 175
Joined: Sun Apr 29, 2012 9:58 pm
Location: Selmer, Tn

Re: BBC output overview.

Post by 408 Nova » Wed Oct 03, 2018 1:19 am

Good to see you back Dave. Now about that third big-block Chevrolet book...you gotta write it! Just kiddin man, I hope you're doing well.

cjperformance
Guru
Guru
Posts: 3216
Joined: Tue Aug 19, 2008 7:20 am
Location: South Australia

Re: BBC output overview.

Post by cjperformance » Wed Oct 03, 2018 2:51 am

David Vizard wrote:
Wed Oct 03, 2018 12:10 am
Headguy wrote:
Tue Oct 02, 2018 11:58 pm
Whatcha selling?
At the moment I am dispensing a free cure for ignorance!
DV
:lol:
Craig.

ozyfordman
New Member
New Member
Posts: 41
Joined: Sun Dec 18, 2016 11:06 pm

Re: BBC output overview.

Post by ozyfordman » Wed Oct 03, 2018 2:59 am

X2 =D>

Geoff2
Expert
Expert
Posts: 991
Joined: Mon Nov 09, 2015 4:36 pm
Location: Australia

Re: BBC output overview.

Post by Geoff2 » Wed Oct 03, 2018 6:06 am

X3

Locked