Thread: LIM Blockage/Coolant Passages Open etc.

Ok.... I've seen pics on people putting dime to block passages on the LIM and making ports bigger somewhere that I don't know of. I need to know where for sure.. What's this all about. I need someone to tell me if I'm missing out in this hack or not.

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The main reason is that by blocking the coolant ports here, you can remove the supercharger/ upper plenum and throttle body without having to drain and bleed the coolant system.

Other main one is those wanting to run an intercooler.

There's other minor reasons that all have their controversy, like it keeps your throttle body colder, you can use throttle body spacers, less likely to leak, L36 coolant and egr issue resolved, etc. (I'm sure I'm missing a free)

The porting is to try to increase the coolant flow rate, especially if the throttle body is bypassed since you are removing that branch of the coolant flow. This is highly debatable, but I'm running nearly 10 degrees cooler on a stock system and thermostat after the port.

Hope this helps!

Originally Posted by wstefan20

The main reason is that by blocking the coolant ports here, you can remove the supercharger/ upper plenum and throttle body without having to drain and bleed the coolant system.

Other main one is those wanting to run an intercooler.

There's other minor reasons that all have their controversy, like it keeps your throttle body colder, you can use throttle body spacers, less likely to leak, L36 coolant and egr issue resolved, etc. (I'm sure I'm missing a free)

The porting is to try to increase the coolant flow rate, especially if the throttle body is bypassed since you are removing that branch of the coolant flow. This is highly debatable, but I'm running nearly 10 degrees cooler on a stock system and thermostat after the port.

Hope this helps!

I'm role'n with an 04 Pontiac Grand Prix Supercharged... Hmm, I might look into how to properly do that.

This is off topic but if you get this and know anything about this please chime in. Recently put in 3' downpipe zzp. 1

1. I only can get one dog bone in because the super strain fit of the downpipe.

2. My Scangauge Boost reading in the negatives when gas is on the peddle. Exhaust leak??

3. My back o2 sensor not plugged in all the way due to the tight fit on the wall and mainly because where the bung is located.

FYI, Just have downpipe for my exhaust work. Installing plog tomorrow..

Thanks if you took the time to read and chime in

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Figured out the problem.Rubber Boot is ripped.. Maybe. Probably why I felt like my RPM was trip'n to make me think my Transmission was slipping. Still hope my transmission not slipping

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Originally Posted by BillBoost37

There shouldn't really be any debate about modding the lim (BTW.. look the up "modding lim" and you should find the thread).

When you plug the coolant ports, you do reduce flow and it's also known that highly modded cars would see a higher temp on cylinders #3 and #4 with them being the middle cylinders. Some guys had issues from the additional heat, especially after blocking the coolant ports and not opening up the turn around area (second pic you have). By opening that area you typically increase flow more than the TB ports. This leads to more even temps across the engine.

As well the L36 with plastic manifold, before they started being made with a metal sleeve as part of the manifold would get hot from the EGR gasses and over time the heat cycling would crack the manifold or it would degrade. When this happens you fill the engine with coolant, which is not overly desirable. Doing this same mod to an L36 car would remove a weakness and nearly bullet proof it.

Great stuff!

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