Intake Port Configuration technical debate

[BurritaSVT]

That is the route I went as well... 3L block with ported 3L heads (SVT Cams), bugzuki LIM plates [allowed me to NOT have to JB weld the injector valley in the oval port head!], SVT LIM with secondairies, SVT UIM. I am very pleased with the setup and it was pretty easy; the next 3L I drop in sometime in the next few weeks will have the Nautaulis Performance LIM so I will be able to give a better opinion on that. I sure the heck am looking forward to the ease of install with it though. No head porting to deal with!

The big negative to the old way with the split port LIM UIM or the plate you bought is the injector is not center port giving it a good burn due to the injector spraying the port walls not center where it should be for a true oval port channel. The negative effect of just adding a plate to the head is that you will create low pressure area behind the plate you bought and the fuel will be drawn into the void and collect. I would never do the plate I would put JB weld before I did that but I welded mine and it looks great that way too. I am buying a project car and we will test all these parts by swapping one day to show what we all want to know. Joey

 

[SHOgoFast]

I am liking the custom LIM idea. Especially the possibility for direct port H20 / Meth injection. Should see some really strong HP/TQ numbers with that. Even on stock internals.

 

[Bradness]

Although I never had "why" info./data, the plate seemed wrong to me too. Seeing as how the info. gathered here suggests that the best configuration is to use the split port heads with the split port intake, could someone comment (Tom?) on the issues regarding this setup?

My understanding is that replacing valve seats in an aluminum cylinder head can be somewhat difficult. Do both the intake and exhaust seats require replacing? What about mods to the combustion chamber? The 3.0 has a slightly higher compression ratio than the 2.5 but still runs regular gas. What octane is req'd for a 2.5 head installed on a 3.0 block? Etc...

 

[warmonger]

Although I never had "why" info./data, the plate seemed wrong to me too. Seeing as how the info. gathered here suggests that the best configuration is to use the split port heads with the split port intake, could someone comment (Tom?) on the issues regarding this setup?

My understanding is that replacing valve seats in an aluminum cylinder head can be somewhat difficult. Do both the intake and exhaust seats require replacing? What about mods to the combustion chamber? The 3.0 has a slightly higher compression ratio than the 2.5 but still runs regular gas. What octane is req'd for a 2.5 head installed on a 3.0 block? Etc...

It's not difficult for a decent machine shop to replace the exhaust seats. The intake seats do NOT need to be replaced, just recut for the slightly bigger valve.

Again, there is not much wrong with the oval-to-split-port conversion even when you retain the IMRC and port the head out for the SVT LIM. The JB weld works when prepped right and the welding also works great.

We want to use the new LIM replacement so that we can have center mounted injectors on the ovalports and still fit the SVT UIM.

I disagree with the concept that the SVT UIM is incapable of high rpm flow on a 3L because of the Plenum size. I think it is sufficient for rpm ranges up to 7000rpm

 

[TourDeForce]

Been investigating the 3L and was wanting some opinions on another potential configuration. I note that the 3L oval ports end up being split further down anyway (in the pictures I've seen), so for my build I thought I might port the ovals to match an SVT LIM, add some material into the head to complete the split port connection, and top it off with an SVT UIM. What I'd end up with is basically a '99 split port 3L head with a proper water pump pulley and my secondaries would be intact.

I'm thinkin' the low end fuel mileage will benefit and a more controlable launch will be possible by keeping the secondaries closed until higher rpm.

The big suck about my project is that it'll be on an ATX equipped car, so the dyno plots will be next to useless unless I end up putting down respectable power by MTX standards - and I doubt that will happen.

Thoughts on this configuration?

 

[Bradness]

Now I don't know how or if this applies to the intake ports on our heads but a hot rodders trick in the old (carb) days was to take a dual plane intake manifold and cut a partial slot in the divider immediately aft of the carb which (supposedly) gave you the advantages of both a dual and a single plane manifold setup.

Really, the only way to figure if this stuff works is by using a flow bench.