Ported LIM?

[Sabrewings]

Anyone know if a company is planning on a ported L36 LIM? Is it just not worth it? Not much room to port? No gains to be had due to head restrictions?

I kinda want one so the coolant holes can be welded shut (blocking off coolant to the UIM and TB so if the UIM fails I don't suck coolant).

[IndeedSS]

Anyone know if a company is planning on a ported L36 LIM? Is it just not worth it? Not much room to port? No gains to be had due to head restrictions?

I kinda want one so the coolant holes can be welded shut (blocking off coolant to the UIM and TB so if the UIM fails I don't suck coolant).

Why did I think you had a top swap?

[Sabrewings]

Because I've been talking about doing it.

[UR LOSN]

gains can be had. blocking off the coolant to the UIM is a great idea!!!

if you ever look at the LIM...it is all rough. this can be smoothed out..much like the combuston chamber of the cylinder heads.

I for one would like to see this done.

[Sabrewings]

if you ever look at the LIM...it is all rough. this can be smoothed out..much like the combuston chamber of the cylinder heads.

Here's something to look at for those who have never had their UIM off:



I think I'll shoot an e-mail to ZZP...

[turbocharged406sbc]

gains can be had. blocking off the coolant to the UIM is a great idea!!!

....

you must cut a 1/4x1/4 grove in the divider under the LIM coolant passage cover.

the TB passage is PART of the rear banks metered coolant flow, block it off without cutting back that divider is reducing rear bank coolant flow...NOT a good thing since its the hotter side of the engine due to reduced air circulation.

please help me spread this info.... its applicable to the L67 and L36, TB coolant deletes are fine, but the coolant flow should be restored by removing a portion of the divider cast into the LIM, under the TB.

i'm still sorting out cause and effects, but at the least an area ~ the same size as the TB passage needs to be removed to restore flow...in some builds checking the F&R head temps may lead to opening it up further to equalize temps and make for even tuning cyl to cyl and allow for reliable power as well as potentially MORE power

[Sabrewings]

you must cut a 1/4x1/4 grove in the divider under the LIM coolant passage cover.

but at the least an area ~ the same size as the TB passage needs to be removed to restore flow...

Is that something you can point out in the picture above? I have more from my gasket disassembly. I'm just having trouble picturing exactly where you're talking about.

Never mind. I get it. You're talking about a little passage between the two coolant holes to keep some coolant moving. So everyone with their LIM holes welded shut, or with TB spacers/plugs are blocking off some coolant to the rear bank?

[turbocharged406sbc]

in the end of the LIM under the TB is the coolant Xover cover...held on with 2 6mmx1.0 bolts (8mm or 5/16ths head)

it covers two holes that are part of the T stat area (hole towards front of car) and the rear bank (towards the rear) the cover itself is the major passage for coolant to get to the T stat from the rear bank, the secondary passage is the TB coolant passage (the whole design is to force coolant to flow through the TB passage cooling the EGR stovepipe area and warming the TB to prevent iceup in cold weather climates)

putting the groove in the top of the LIM is more work than needed, the end cover is accessible with the topend together for fine tuning the (now) larger passage to equalize F and R bank temps.

[Sabrewings]

You'll have to excuse me. I'm trying to follow. I appreciate the help.

In the LIM under the TB is a cover of some sort. It allows coolant to flow to the rear bank. I would need to remove this cover and cut a divot to allow coolant to flow if the TB is blocked off (since it's part of the rear bank's flow).

What I don't understand is where this divider is. Is it part of the cover, or part of the LIM? I'd have to figure out something to cut the divot path with. Maybe my dremel can do it...

Edit: Is this cover what holds the EGR tube in? I remember that piece being rather large for that purpose...

[turbocharged406sbc]

You'll have to excuse me. I'm trying to follow. I appreciate the help.

In the LIM under the TB is a cover of some sort. It allows coolant to flow to the rear bank. I would need to remove this cover and cut a divot to allow coolant to flow if the TB is blocked off (since it's part of the rear bank's flow).

What I don't understand is where this divider is. Is it part of the cover, or part of the LIM? I'd have to figure out something to cut the divot path with. Maybe my dremel can do it...

Edit: Is this cover what holds the EGR tube in? I remember that piece being rather large for that purpose...

look just below it.... the groove is ground into the divider wall thats port of the LIM casting, if you have an LIM gasket set they USUALLY include the cover gasket (a 1.25x4 inch rectangle with a bolt hole at each end)

the cover and the gasket are the major flow path around that divider.

your dermel will do fine, a 3" cutoff wheel can be used to cut the grooves as well as a 4 or 4.5" grinder and will be faster.

you want a min 1/4 x 1/4 inch passage...

[Sabrewings]

My gasket set didn't come with one. Came with the following pieces:



Okay, so below the EGR plate is this cover. The divider is part of the LIM, and I'd cut a 1/4" by 1/4" path in the divider to supplement what is lost by blocking the coolant flow through the throttle body.

To be clear, though, the bypassed TB doesn't completely cut off the coolant flor for the rear bank, only decreases it right?

I think I got this. Thanks very much!! I might go ahead and do the cutting when I have the crossover off so I have more room in that area. Or the throttle body might come off or something. Gonna be tight to get my dremel in there.

[turbocharged406sbc]

My gasket set didn't come with one. Came with the following pieces:

Okay, so below the EGR plate is this cover. The divider is part of the LIM, and I'd cut a 1/4" by 1/4" path in the divider to supplement what is lost by blocking the coolant flow through the throttle body.

To be clear, though, the bypassed TB doesn't completely cut off the coolant flor for the rear bank, only decreases it right?

I think I got this. Thanks very much!! I might go ahead and do the cutting when I have the crossover off so I have more room in that area. Or the throttle body might come off or something. Gonna be tight to get my dremel in there.

yes it only decreases the rear bank flow, by the flow area it appears to be at ~12-14%
if you pull the TB you wont have to pull the Xover as you can get the good fiber cuttoff disks for the dremmel and cut at 90*...to use the grinder/cutoff will req removal of the xover for tool clearance.

if you have an IR temp gun you may want to check front and rear head temps before and after removing the divider, by trial and error you can "sneak" up on the proper ammount to remove to equalize front and rear temps.

sorry i meant head set (for the gasket) it is available from the dealer individually

[agrazela]

L36 Ported LIM's are well documented over on bonnevilleclub.com

Go there and search on "ported LIM" or "PLIM" and you'll find lots of info.

Here's one I'm doing right now (with pics):
Bonneville Club :: View topic - Ported LIM

I plugged the TB coolant ports with stainless steel pipe plugs, and I opened those coolant ports under the cap to exactly match the area of the coolant ports on the sides of the LIM.

EDIT: You are going to have to remove the LIM to grind on it...you don't want to get all those aluminum shavings into your intake or cooling system.

[Sabrewings]

What tools do you use to do the porting? Also how much do you charge for the service? I'm sure the gains will be fairly substantial since you opened the runner exits a lot. Probably pretty close to the opening in the heads, by the looks of it (why GM didn't do that from the start I don't know... ).

Good work!