Swazo's Modified LIM - CEG Archives

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I thought I'd share some pics of my gutted and modified LIM that I put some of my own twists on for my tumble port heads.

Here is a pic of the bottom side of the LIM. I reshaped the port heavily as you can see.

The top side is still split port, but it was also ported.

The LIM was gutted and the secondary butterfly shaft holes were filled with Kop Coat. I reworked this LIM to work better with my 3L aluminum UIM and the tumble port 3L heads.

Thoughts?

Pretty cool.

I think it looks awesome. Needs some polishing, and some paintwork on the outside... lol

Originally posted by warmonger:
I think it looks awesome. Needs some polishing, and some paintwork on the outside... lol

you mean like this?

but swazo, that looks awsome... any advice for someone who wants to give this a try?

Non-ferrus cutting bits and assorted grit flap wheels make short work of porting these. Cross buffs polish them out pretty nice.

It looks pretty grimey, but that's how it looked as it came off the engine upon tear down. I didn't bother painting it or anything since it's hidden for the most part between the heads.

I thought I'd atleast post a few pics of what I did, just to get people thinking outside of the box a little. I thought this may help merge both ports into the tumble port heads a little bit better. Something like this LIM with an SVT UIM might work out even better.

thanks swazo, but I was mainly looking for a stratagy on determining the shape [you know tracing out the gasket, how deep you made the seperation, did you volumn test it]

Both port sizes were gasket matched. I'll get a pic of the modified LIM to Head gasket that I used to get the bottom port shape.

Once you take the secondary shaft out, I ported up to that hole which is about half way up. It transitions from the rounded circle 8 shaped port to a knife edged divider.

I also beveled the edge wround the injector port to allow the spray pattern to fan out a bit more..... if it needed to. That was a just in-case type thing as I didn't know what my injecotrs spray pattern was like (wide or narrow pattern).

I didn't volume match the LIM, which would have been ideal.

What did you do about the gasket that has the crossbar in it. I was thinking about doing this to the LIM, but will the gasket hold its form?

When you ported the heads did you take them off and take the valves out?

Have you noticed any torque loss not having the secondaries. I want to dump mine. It bothers me that there is so much of a power gain when they open that people ask me if I have a turbo. Obviously timed wrong.

Do you worry about the filler coming out of the holes?

Thanks

Originally posted by Swazo:
I also beveled the edge wround the injector port to allow the spray pattern to fan out a bit more

I did the same thing to the underside of the injector boss. I also widened the outlets of the secondary ports like you did both ports. The primary ports are feeding much slower air so...

Originally posted by Bugzuki:

1. What did you do about the gasket that has the crossbar in it. I was thinking about doing this to the LIM, but will the gasket hold its form?

2. When you ported the heads did you take them off and take the valves out?

3. Have you noticed any torque loss not having the secondaries. I want to dump mine. It bothers me that there is so much of a power gain when they open that people ask me if I have a turbo. Obviously timed wrong.

4. Do you worry about the filler coming out of the holes?

Thanks

1. I had no problems with the crossbar removed. Barely tack them into place with some tiny dabs of contact cement so they seat where they should between the LIM and the heads, until the LIM is torqued down.

2. Yes, that's the only way to do them properly. There is a TON of bowl clean up and valve seal to bowl size matching that needs to be done. I took my heads in to have a full radius valve job after just to be on the safe side.

3. Not at all, even at the 'lame' 3.5psi I was putting out some serious power

4. No. Kop Coat is a very good product and there are other aluminum epoxy type products that are way easier to find that would do a good job too. To be safe, just rough up the holes with 60 grit to give the product something to bite into as it drys/cures.

Originally posted by DemonSVT:

Originally posted by Swazo:
I also beveled the edge wround the injector port to allow the spray pattern to fan out a bit more

I did the same thing to the underside of the injector boss. I also widened the outlets of the secondary ports like you did both ports. The primary ports are feeding much slower air so...

Sweet, I take that as a sign I was on the right track

I did both ports because I was using the Aluminum 3L UIM, not the SVT UIM.

I put the SVT LIM gasket on the head last night. It looks like there is a number of places where the cutouts will make the walls mighty thin in some spots.

Has anyone had any problems with that?

I was also looking at the effect of leaving the secondary valves in. It seems to me that with the oval heads the secondaries would create less turbulance at low RPM. This is because the Secondary runner would be blocked off restricting the flow through to just the long runner. Then when the air enters the head it would open up to a larger space and enter the cylinder through both valves instead of just one - like on the 2.5 heads.

I am definitely taking the secondary butterflies out. Anybody else have any comments or thoughts?