task Posted April 16, 2012 Share Posted April 16, 2012 Has anyone had a go at this? I have some nice cylinder heads now to go on my soon to be built 4.6 block, they've been ported/flowed, this leads to the issue that I don't have a ported/flowed inlet manifold. The method I used to try and marry the two up was as follows, cardboard template on cylinder head, knock/cut out bolt holes for inlet manifold to give a line. knock/cut out the inlet ports. Move template to inlet manifold, line up with bolt holes. This is where I lost faith in my method, having traced out on the head where the material needed to be removed from to get rid of lips on the mating surfaces I couldn't be sure it was 100% accurate! Any ideas or tips? The above shows the cylinder head I took the template from and the inlet manifold I'm transferring the port size to. Thanks Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted April 16, 2012 Share Posted April 16, 2012 Nice looking heads I used pretty much the same method, drew around the area to remove with a sharpie, then get grinding/blending. You can get perfomance inlets IIRC, but depends what you want to spend.... Quote Link to comment Share on other sites More sharing options...
task Posted April 16, 2012 Author Share Posted April 16, 2012 Thanks, I'll put some photos up in my build thread I've seen the ported inlets for sale but I would then have the same problem with the trumpet base, unless I purchased one of those too. There is quite a lot of material to pull out of the throat/mating surface, I'm not planning on chasing it all the way through to the trumpets. This manifold also has the snap-in bosses for my SGi injectors tapped, not a job I really want to risk doing on a expensive ported manifold and something that I think would be difficult if a lot of material has been removed from the inside. Marker pen is a good idea, I was using a scribe after wet/drying the surface to remove the gasket marks, marker pen will be much easier to see! I guess at the end of the day it doesn't need to be 100% accurate as anything will help to improve airflow. Quote Link to comment Share on other sites More sharing options...
fozsug Posted April 16, 2012 Share Posted April 16, 2012 How about engineers blue? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted April 16, 2012 Share Posted April 16, 2012 I guess at the end of the day it doesn't need to be 100% accurate as anything will help to improve airflow. Exactly! Getting it pretty damned near is much better than the 5mm step you now have I left the other end of the inlet and trumpets alone, there's not much to be gained here. If your heads are skimmed... you may want to try and find out if you need to skin the inlet, as the V of the heads gets smaller as more head material is removed, mine is JUST okay, need to jiggle the inlet to get all the bolts in cleanly. Quote Link to comment Share on other sites More sharing options...
task Posted April 16, 2012 Author Share Posted April 16, 2012 How about engineers blue? That had been suggested by someone else too, to do that am I right in thinking I'd need to bolt the heads down to a block (with gaskets fitted) and then fit the inlet manifold (again with a gasket)? I'd need to find some scrap gaskets, or take the heads off a spare engine I have in the shed. It would give more accurate results though. Bowie; the heads should have been cc'd to the standard capacity and I don't think they've been skimmed beyond facing them, will find out when I try to fit them though! Quote Link to comment Share on other sites More sharing options...
fozsug Posted April 16, 2012 Share Posted April 16, 2012 To do acurately, then yes with gaskets. Quote Link to comment Share on other sites More sharing options...
fozsug Posted April 16, 2012 Share Posted April 16, 2012 A Bit of V8 Inlet manifold porn can been seen here http://www.mez.co.uk/ms12.html Quote Link to comment Share on other sites More sharing options...
Soren Frimodt Posted April 19, 2012 Share Posted April 19, 2012 I usually do it this way: Take the new gasket and put it over the hole that is bigger than in the gasket (in your case the heads) gently use the carbide bit to match the gasket to the whole. After this move the gasket to the manifold, mark with whatever you prefer, and use the carbide bit again, and hey ho, away you go! Quote Link to comment Share on other sites More sharing options...
cackshifter Posted April 20, 2012 Share Posted April 20, 2012 You really need to put in a couple of dowels to maintain the alignment, otherwise it's chance how it ends up, as there is usually quite a bit of wiggle. Nigel Quote Link to comment Share on other sites More sharing options...
ian_s Posted April 21, 2012 Share Posted April 21, 2012 have you posted on v8 forum about this? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted April 21, 2012 Share Posted April 21, 2012 I'm not really clued up on engine mods...is port matching purely for petrols or would it be of benefit to my TDi's? I understand that its all about better airflow by removing the steps - I'm a subcontractor for the power turbine industry and we have to blend casting joint faces for this reason. Does it improve MPG, HP, Torque? Quote Link to comment Share on other sites More sharing options...
dirtyninety Posted April 21, 2012 Share Posted April 21, 2012 I'm not really clued up on engine mods...is port matching purely for petrols or would it be of benefit to my TDi's? I understand that its all about better airflow by removing the steps - I'm a subcontractor for the power turbine industry and we have to blend casting joint faces for this reason. Does it improve MPG, HP, Torque? It does have a very small effect on turbo diesels, the easier the air can flow the less power is wasted blowing air in. Im not sure you'd notice the difference, perhaps on a engine dyno you might see the results. It depends if your a perfectionist! I have smoothed a 200tdi intake manifold before, just because its easy and you sound cool telling your mates in the pub Quote Link to comment Share on other sites More sharing options...
task Posted April 21, 2012 Author Share Posted April 21, 2012 Well, I bit the bullet and did something about this today. Mounted the heads on a spare 3.9 engine and bolted them down with some old gaskets. smeared engineers blue on the head faces; Placed the manifold on and nipped it down, then removed it and coloured the bits that need to be removed with a marker; Removed the material and checked again. I would guess it's not going to be 100% accurate, especially as it's not the final block I'll be using and the thickness of the gasket wasn't in place. I've been a little conservative in what I removed so we'll see This is where I got up to; They need cleaning up and smoothing out, then I'll attack the other side. My theory is it's got to be better than it was before I removed anything! Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted April 21, 2012 Share Posted April 21, 2012 My theory is it's got to be better than it was before I removed anything! My reading on the subject suggests that's probably not the case. On a V8 the inlet manifold ports are always smaller as it's essential that you don't have a step to the heads, a step the other way makes no difference to performance. It's not possible to ensure V8 inlet manifolds and heads are always aligned in the same place as you can't dowl them. Therefore by enlarging the ports on the inlet manifold you will almost certainly introduce a step to the head and reduce performance. There was an informative article by David Barker of Puma Racing on the subject but his website has been compromised. There is a fairly comprehensive thread on the subject in the pistonheads archive. However, I'm not an engine builder and haven't done back to back dyno tests to confirm one way or the other. Quote Link to comment Share on other sites More sharing options...
task Posted April 21, 2012 Author Share Posted April 21, 2012 Surely a step as large as this was, 5mm or so, is going to be worse than a step of 1mm or less now. I would have thought such a step would introduce vortexes in the air flow? There is still more meat on the inlet manifold port than then head port so still an increase in diameter and no step down between the two. Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted April 22, 2012 Share Posted April 22, 2012 I'd always thought the same as you and was concerned about a step on my exhausts, that's when I did more research. I'm not sure you'd feel a difference either way so probably not worth losing sleep over. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.