![]() |
|
|
|
Registered
Join Date: Jul 2008
Location: Baltimore, MD
Posts: 153
|
Porting manifolds question? How to?
I have a set of PMO manifolds, well they look just like them, a few years old, so not sure if they are real PMO ones. Anyway, I have opened my intake ports up a few mm and need to match port the intake manifolds now.
Center is super easy, but the outside runners are not a straight shot. Any tips on porting these. Was thinking of using specific diameter flapper sanding wheels and porting them that way. Theyshould stay round and I can control the angles. Any other options to get the bulk material cut away? Do not want to spend the money for extrude honing, so will need a DIY at home way and milling will give an improper taper i believe. Thanks again.
__________________
2000 VW TDI 224HP/400FT TQ. Pikes Peak World Record Holder 2007 "Fastest Diesel Car" 1973 Porsche 914/6 2.4L Engine rebuild in progress |
||
![]() |
|
I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
|
I use a cheap set of rotary files from HF. They are a few bucks for a set of 4 in different shapes. Then I chuck them in a drill (not battery powered) and start milling. This will remove the bulk material and you can finish with a flap or rotary sanding setup on a die-grinder.
__________________
Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
||
![]() |
|
Try not, Do or Do not
|
Matching the manifolds to the ports is not all that important.
As long as the port in the head is larger than the manifold your good to go. There is a school of thought that suggests the use of a 2 mm transition actually improves low rpm performance in carbureted engines.
__________________
Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net |
||
![]() |
|
Registered
Join Date: Jul 2008
Location: Baltimore, MD
Posts: 153
|
Quote:
__________________
2000 VW TDI 224HP/400FT TQ. Pikes Peak World Record Holder 2007 "Fastest Diesel Car" 1973 Porsche 914/6 2.4L Engine rebuild in progress |
||
![]() |
|
Registered
Join Date: Jul 2000
Location: So. Calif.
Posts: 19,910
|
Paint the manifold mounted surface with machinist blue, then scribe the larger diameter using the appropriate gasket as a template.
I use Jamie's (JPNovak) method on a drill press. Moving the manifold by hand relative to a stationary tool is a lot more precise than hand holding a high speed cutter and grinder. ![]() An add'l DIY tip: Use a piece of cardboard the size of your target port size, then run a short length of wire through it for a handle (or equivalent) to help visualize the shape and amount of port material to remove. Not sure the many hundreds Extrude-Hone charges is worth it for the relatively short length of these intake manifolds. Sherwood |
||
![]() |
|
Registered
|
Quote:
How about if one is going beyond a few millimeters. Say as an example, I've currently got small port SC heads with the smaller PMO intakes at 34mm. I go to a 40 mm 3.2 head? Is the 34mm manifold too restrictive then? The rest of the upgrade is designed around a hot street/ autox setup with DC40 or GT2 Cam, 9.5 95 mm JE's, & possibly twin plug.
__________________
joe ------------------ '69 911 E Targa - aka "RoxiE" |
||
![]() |
|
![]() |
Try not, Do or Do not
|
We are using a new port design that affords us the velocity of a small diameter port and the flow of a large port.
We are generating 310 hp @ 7200 with 95 mm bore, 70.4 mm stroke ,10.5:1 comp., twin plug and MFI with 1 5/8" headers. 310 hp 3.0 through a 36mm port. For us, the days of large ports ( 43mm intake RSR nonsense) on early 911 engines is over. Large ports only make sense on a large 8000 rpm engine and even at that, 41mm is the max. That number can go up if larger valves are employed.
__________________
Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net |
||
![]() |
|
Registered
Join Date: Jul 2008
Location: Baltimore, MD
Posts: 153
|
I have measured my manifolds and heads and I was completely turned around on what I needed to do. Long time since I looked at the stuff. I opened the heads slightly to match the manifolds. Ports are 34.5mm on the intake side. So have 40-34.5 manifolds as pictured below. So I just need to clean the heads up slightly from the machining and send them off to get finished.
![]()
__________________
2000 VW TDI 224HP/400FT TQ. Pikes Peak World Record Holder 2007 "Fastest Diesel Car" 1973 Porsche 914/6 2.4L Engine rebuild in progress |
||
![]() |
|