plenum question

87LimitedT

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Dec 11, 2007
is their any difference between an 86 and a 87 upper plenum i was looking at the one that i have on the car and an extra one i bought from some guy here in town they look a little different in the inside here is a pick of the extra i have what year is it.
 

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this is not mine but this is what it looks like on my 87 limited
 

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I dont think the 86/87 are different. The first pic appears to be ported and the bottom one is stock.

Hopefully someone smarter than me will confirm that.
 
As far as I know, they are not different. The picture at the top appears to be an aftermarket upper plenum. :confused: The second picture looks like a stock piece.
 
it also has some numbers on the back
#25525146
 

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i dont think its stock look around the back bolt hole in the second pic the opening is around the hole halfway and the top pic its solid.it would have to be welded up to get it solid that far into the plenum if this were the case
 
I think the top one is a modded stock plenum. Before hemco you could send out your upper plenum and have a pie piece of metal welded in. i had one years ago and it worked well. It might also be ported to 62mm.
 
could the numbers on the back tell u guys anything about it, it does look like someone did somthing to it the inlet looks like sombody has tried to open it up more.the numbers are 25525146.
 

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The top one is a modded STOCK plenum. I don't recall who use to do that. (besides me). That was an OLD mod from years gone by. It "kinda" works good. I think that the RJC power plate works better for "most". I use to weld in a flat plate to try and direct the airflow into the middle of the lower manifold. I found that it really didn't make a whole lot of difference. Just turning the boost and fuel pressure up a notch, made more power. But, heck, what do I know.:p This is also another "version" of the same concept: http://www.turbobuick.com/forums/general-turbo-buick-tech/210845-top-sekret-teknology.html Look down to my post. Fun times coming up with stuff like that.:) To answer your original question, though........There is NO difference in 86-87 upper plenums A.K.A "Dog House"
 
could the numbers on the back tell u guys anything about it, it does look like someone did somthing to it the inlet looks like sombody has tried to open it up more.the numbers are 25525146.

wow, the inlet on the plenum looks kinda wavy...not round!

im pretty sure that a stocker cause "255" numbers are GM part numbers, correct?

ah it is indeed, check out 1986-87 Common parts for Turbo Regals
scroll down to (intake, upper plenum) and u will find ur number!
 
The top one is a stock GM piece modified inside to get a more even air flow. Used to get them from BGC, ATR (I think) and Mike when it was Modern Muscle Car?? The second one is an 86-87 stocker. I still have one of them.
 
so id probably be better of putting a rjc plat rather than this or would both work for me.
 
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