How to identify aftermarket plenum

2QUICK2B6

Black Car Fever
Joined
Sep 15, 2004
How to identify aftermarket plenum
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1986 Buick GX1

GX1 #001 [The One and Only]
Joined
Apr 24, 2015
I looks like a non polished Precision plenum to me.
If you zoom in on the plenum on the RJC Racing website it looks the same, plus I have one too.


The Hemco’s have a smaller more square hole on the intake side to help even out air flow.

The Accufab/ Kenne-bell plenums were more flat on top like a stock one.

That’s all I know.
 

1986 Buick GX1

GX1 #001 [The One and Only]
Joined
Apr 24, 2015
That seems beyond fair what u think ?

A new setup is $540, so I think it’s fair.
The Precision plenum and RJC racing ADPP (air distribution power plate) has the most even airflow of all of them.

I went with the Precision plenum and power plate for this reason, using a Steve Monroe modded/ rebuilt stock throttle body (62mm) to go with some flow matched injectors.

Without the power plate the rear cylinders go lean and will detonate while the others run rich.
Typically, you can run a couple more pounds of boost with no detonation using any matching power plate no matter what plenum is used.

If you check out the charts the Accufab /w power plate is tied for second behind the Precision /w power plate.


The Precision plenum is 5/8” taller to clear a 4” maf pipe whereas the Accufab is not as tall for what it’s worth.
 

1986 Buick GX1

GX1 #001 [The One and Only]
Joined
Apr 24, 2015
A new setup is $540, so I think it’s fair.
The Precision plenum and RJC racing ADPP (air distribution power plate) has the most even airflow of all of them.

I went with the Precision plenum and power plate for this reason, using a Steve Monroe modded/ rebuilt stock throttle body (62mm) to go with some flow matched injectors.

Without the power plate the rear cylinders go lean and will detonate while the others run rich.
Typically, you can run a couple more pounds of boost with no detonation using any matching power plate no matter what plenum is used.

If you check out the charts the Accufab /w power plate is tied for second behind the Precision /w power plate.


The Precision plenum is 5/8” taller to clear a 4” maf pipe whereas the Accufab is not as tall for what it’s worth.

The Accufab plenum is the same height as stock, since we can’t edit.
 

2QUICK2B6

Black Car Fever
Joined
Sep 15, 2004
Blew a hg with same Tb an plenum with rjc but I was high boost bad converter on stock long block an it was fine 1/8 but 1/4 it has been lifting the heads
 

2QUICK2B6

Black Car Fever
Joined
Sep 15, 2004
I’ve learnt Lot over the yrs but I put the Buick’s an ttas aside for awhile .. made some money with cam converter ls1 z28 hardtop 99 with nitrious everyone said I had a built motor till time to sell lol
 

2QUICK2B6

Black Car Fever
Joined
Sep 15, 2004
Bought it for parts 16 yrs ago to nice to strip.. t tops only thing I hate abt it thdp te44 I’m sure it needs a fuel pump now as my 2 gn’s an 2 ttas do an my low mile 99 ss vert 6 speed 1 of 365 does
 
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