Porting the VW/Audi 8v head with port energy discussion
Moderator: Team
Re: Porting the VW/Audi 8v head with port energy discussion
Interestingly the period factory-backed competition heads I've seen pictures of had the guides just cut off flush with the top of the head. Of course that leaves you with a guide that is about a half inch long so lifespan is short.
-
- Guru
- Posts: 2694
- Joined: Fri Jan 09, 2009 8:51 pm
- Location: Australia
Re: Porting the VW/Audi 8v head with port energy discussion
There would be some real good gains to be had welding up those bathtub chambers & cutting a proper pressure recovery chamber into them.
I won't show much on the flow bench, but the engine will love it.
I won't show much on the flow bench, but the engine will love it.
Re: Porting the VW/Audi 8v head with port energy discussion
This is actually on the program but I don't have a complete shop so some will need to be farmed out. Pop the seats, weld the chambers, install bigger seats, custom shaped chambers. I am thinking nearly a figure 8 shape. We will see how it developes. Thanks, CharlieKnightEngines wrote: ↑Mon Nov 06, 2017 9:48 pm There would be some real good gains to be had welding up those bathtub chambers & cutting a proper pressure recovery chamber into them.
I won't show much on the flow bench, but the engine will love it.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
Different approaches to tiny bowls and guides in the way. Top photo is 8mm guide mowed down to see how much flow would be gained with a better bowl shape and no guide. Worth 7 cfm on a tiny port which is a big gain. I am thinking the bucket lifter arrangement has very little to no side loading to the guide so a shorter guide may still have a long life. Bottom pic popped guide reshaped bowl and reinstalled guide worth 9 cfm.
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
vw 8v stock vs. 7th porting and flow tests.
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
vw 8v stock vs 7th porting flows cfm/sqin graph.
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
vw 8v stock vs. 7th porting flows velocity graph
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
vw 8v stock vs 7th porting flows port energy graph
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
vw 8v stock vs. 7th porting flows port energy density graph.
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
Re: Porting the VW/Audi 8v head with port energy discussion
since you are testing guides. bullet/cone shape one and test. also maybe shaped like a vane?
Re: Porting the VW/Audi 8v head with port energy discussion
Not my best photo but I would like some input. My smallest exhaust pipe is 1 5/8" tube which does boost exhaust flow but I feel it is too big for an engine that will need a wide torque band. Thinking about a 1.3" pipe would be about right I looked through some scrap aluminum conduit I had and found 1.375" id which looks good but does not leave a huge anti reversion damn. Input welcome. Thanks, Charlie
You do not have the required permissions to view the files attached to this post.
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
-
- Guru
- Posts: 3661
- Joined: Tue Aug 19, 2008 7:20 am
- Location: South Australia
Re: Porting the VW/Audi 8v head with port energy discussion
The closer you get the port face and pipe size to being correct and the better the design and combo match the pipes are the less you need to worry about anti reversion dams. Ie- So if its all spot on then a match at the port is best but the worse it all gets the more anti reversion stuff will help.
In the case you show id be happier to run the smaller pipe and less mismatch.
In the case you show id be happier to run the smaller pipe and less mismatch.
Craig.
Re: Porting the VW/Audi 8v head with port energy discussion
Do you think that's really true in a street motor? The pipe size to make a certain hp at certain rpm like 7000 or whatever is always going to be too large at low to medium rpm why wouldn't AR things always work effectively ?cjperformance wrote: ↑Wed Nov 08, 2017 11:44 pm The closer you get the port face and pipe size to being correct and the better the design and combo match the pipes are the less you need to worry about anti reversion dams. Ie- So if its all spot on then a match at the port is best but the worse it all gets the more anti reversion stuff will help.
In the case you show id be happier to run the smaller pipe and less mismatch.
Re: Porting the VW/Audi 8v head with port energy discussion
I started using anti reversion techniques on my engines back in the 90's and have always had good luck. As in running a bigger cam than usually advised from cam coaches of the day with better than most street manners with come up on cam right now power. I think using AR on this build will really help. Thanks, Charlie
Servedio Cylinder Head Development
631-816-4911
9:00am - 9:00pm EST
631-816-4911
9:00am - 9:00pm EST
-
- Guru
- Posts: 3661
- Joined: Tue Aug 19, 2008 7:20 am
- Location: South Australia
Re: Porting the VW/Audi 8v head with port energy discussion
In a street motor,,, yes if getting that ar dam means going 'up' a pipe size! Why put a bigger lazier less responsive primary pipe on it just the get an ar dam?digger wrote: ↑Thu Nov 09, 2017 6:51 amDo you think that's really true in a street motor? The pipe size to make a certain hp at certain rpm like 7000 or whatever is always going to be too large at low to medium rpm why wouldn't AR things always work effectively ?cjperformance wrote: ↑Wed Nov 08, 2017 11:44 pm The closer you get the port face and pipe size to being correct and the better the design and combo match the pipes are the less you need to worry about anti reversion dams. Ie- So if its all spot on then a match at the port is best but the worse it all gets the more anti reversion stuff will help.
In the case you show id be happier to run the smaller pipe and less mismatch.
Craig.