I plan to have a crack at porting my heads and port matching the plenums. I am coming into this with some knowledge but I am after some advice from others who have done their own porting. I am a noob at porting but I'm not mechanically retarded (all though it may sound like it through this thread). I will post pics through this thread so that it could be come a visual guide to anyone who wants to attempt this themselves. I have a spare set of heads and plenums that I will be attempting this on before I do the job properly on the new engine's heads. Firstly port matching the lower plenum to the heads. First question is about where most of the metal comes off when port matching the lower plenum to the head. Does most of it come off the roof of the port/plenum or is the same amount of metal taken off all around? My intial thought were to first gasket match the two individualy an blindly hope they line up. I decided against it and attatch the lower plenum to see how well they lined up. Aligning the lower plenum to the head is difficult when the head isnt on the block as there is 2mm play between the two when the bolts are in. If I align so the bolts are exactly in the middle of the holes and tighten it up Most of the floors of the runner are close to lining up. By close I mean there was only about .5mm to come off to make it match. This leaves 2-3mm to come off the roof of the lower plenum. Is this normal or am I completely of of alignment? As can be seen in this photo, More metal has to come off the top of the port to be gasket matched. It is only aligned this way as the floors lined up close and I cant see a point in removing metal if it already lines up.
Hey Al, When I ported my heads i basically did what you have described by taking out the metal so it matched the gasket. This prevents turbulence from the incoming air hitting these edges and essentially reducing velocity. For the lower plenum and upper plenum where you can't sit the gaskets on a stud, you need to bearing blue the faces and then make the ports with the gasket lined up perfectly to guide how much metal needs to be removed. A general hit with a course sanding drum to deflash the ports is a good task as well. Polishing on the inlet runners is not advised as it assists with the fuel and air mix by having a small amount of turbulence. Polishing is a good thing on the exhaust runners as this helps to reduce carbon deposition which essentially is fowling in it's infancy. If you run you finger inside the ports toward the valve seat you will notice quite a large ledge or lip there. This area is where a lot of improvement is made. Take the metal out so this is smooth all the way through but be dam careful to not mark the seat or you will need to lap them. Probably not a bad idea to lap and reseat the valves anyway. My advice is to buy yourself a Standard Abrasives Deluxe Porting Kit. Not only does it have an assortment of stones, sanding drums and cross buffs but a very detailed pamphlet showing you exactly how to port cylinder heads and what abrasives to use and how to use them.
I have the standard abrasives porting kit too, real comprehensive kit for any porting job you will need to do. Be aware that gasket matching will work, but the whole intake manifolds and heads will sit differently once all torqued down. Gasket matching will work, but it all comes down to how picky you want to be about it.
definately remove the step on the short radius. also be aware that once the valve seats are oversized it may require a touch more blend work
I got the smarts today and mounted the heads and plenum back onto the block with their gaskets. I was relieved to find that all the floors were close so I wasn't out with my alignment after all. Since most of the metal was coming off the roof of the lower plenum I ran into issues with the injector inlet. My thoughts were to shape the valley that exists after the injector in the head back onto the lower plenum. Photos will explain. As can be seen, the injector still isn't exposed. I dont know if what I have done is good or bad. While the ports now match up I'm worried that it may effect the atomization of the fuel. What have others done in this situation? While I was playing this arvo i thought id also take the steps off the sort turn in both intake and exhaust. The reshaped intake can be seen in the previous photo. I have also heard that a few mm of metal can be taken of the entire short turn in the exhaust to improve flow so I had a crack at it as the following photos will hopefully show. Before After
Some good posts here... Some useful advice/pics here so keep em coming I just got both TT heads with cams from ebay for 110 bucks, my engine is dead and needs a rebuild (going on to the engine stand on tuesday and will be pulled apart for furthur inspection, not 100% sure on whats damaged) so for a little more than a hundred got some spare parts in case something is wrong with my existing heads So might attempt some porting...
I always thought that hole (venturi) was there to assist the spray pattern of the injectors. Im unsure of how what you have done will affect this.
Had an interesting talk with an race engine builder today. I rocked up out of the blue and out of sheer fluke, he was in the middle of flow testing a vg30 head that he was working on. The engine he was working on was a 600hp motor that he did last year and it was back to get the heads further ported to try get some more out of it. In his opinion (and he has done a few high hp vg30's) there was no point in port matching the intake. The biggest restrictions were in the head not the plenum and no real big gains could be had from it. His suggestions to get the best flow. 1. Remove the lips on the short turns as others have suggested 2. Remove the huge lump that the exhaust valve stem seal comes through. (Big improvements on that one) I asked about valve stem wear and he claimed that with stainless valves it would be no different to a full length stem seal. 3. Machine the inner circumference of the valve seat to the point that only 1 mm of the valve, seats with the valve seat . (extra 40cfm per valve he claims) With standard exhuast valves it will eventually cut into the valve (he showed me one from another engine. But with aftermarket valves it shouldnt be an issue. 4. Leave the intake and exhaust ports alone(not gasket matching) as it slows down the flow of air. He also had some cross section cuts of a head and gave me a warning that I will pass on to anyone who is going to try porting. Do not remove any metal on the inside edge of the divider between the of exhaust ports. (This is the one that many put a knife edge on) There is only about 3mm of metal before you hit a water channel. He has seen heads cracking in this spot due to over porting. Some very interesting info from this guy and I'm gonna try get some graphs out of him as he was measuring port flow in relation to valve opening. He didn't answer my earlier question though. What have others done with the lower plenum when they were port matching them?
I dont open the lower plenum up as far as you have. I believe the injector opening is there to increase air speed around the nozzle to help prevent fuel pooling. I port match the upper to lower and lower to heads, on the exhaust side I dont port match but make the manifold to port join even all the way around. Also polish the exhaust ports and chamber to a mirror like finish, do not do this to the intake, an 80 grit flapper wheel to finish the intakes is enough. If you are using standard or cheap valves do not touch the guides and leave the seats quite wide. I will post up some pics on firday of a set i am doing at the moment with o/s ferrea valves to give you an idea.
Port matching is one of the best ways to increase overall dimension and airflow throughout the cylinder heads. A smooth transition with no major increases or decreases in size and volume is best suited for FI applications. Best way to mark your gasket to the flange is by doing what you've done there and scribe the gasket line and begin to blend. I suggest using a carbide bit instead of stones as the stones will get caked with aluminum material. Using a carbide will aid in a faster work progression and as always use wd-40 to lubricate the area you are port matching. If anyone here has any questions regarding such work you can PM me or I can post images up showing details and ques.
I want to know if you should remove the Venturi by the Injector or not. This question does not seem to be getting answered.
i remove it on some applications. Those that are doing a full race port I do this..on street applications I leave it alone but do a light sanding to it
Thanks for the wd-40 idea. I went out and purchase a set of 9 mixed carbide tips before I started as stones are a PITA. There has to be an answer as you cant match the lower plenum to the head without remove that 2-3mm step. even removing a little bit of metal is going to change the shape of the ventur TECH @EPR please post up some pics:bow2:
I asked about matching the lower plenum to the heads, and was told It would make FA difference unless I was aiming at 6-700rwhp circuit car race engine, and even then the gain would be small.
ok...when I get home I'll post up some images. Im at work now. I'll be at home around midnight central US time.
Oversized valves fit down the intake ports. Yes...I can port them larger if you are wondering but these are the biggest heads out right now that a customer of mine has... Here is of the latest cylinder head that was a collaboration between my buddy and myself for a customer of ours here local.. Thats just a few for you guys to look at. If you guys have any questions feel free to PM me. If you are interested in getting any work done let me know. Happy viewing
Wow they are some majorly opened up heads. Do you have any flow charts or measurements for them? Do you have a photo of what you have done to the lower plenum to match up to those openings? Visually looking at you pics and comparing them to mine, air speed coming into ports that big would definitely slow down, unless you have done serious lower plenum work?
i can assist ,, when you hit boost , the air flow will push the fuel straight to the head , instead of injecting the fuel down into the chamber. this is something of a no no in the porting world
