which heads should i use? TGP or N/A?

[TurboSedan]

i'm going to be turbocharging the N/A 3.1 MPFI engine in my Cutlass using TGP parts. i'll be changing the head gaskets and installing new head bolts soon. should i use the '91 N/A cylinder heads on the motor right now or should i use TGP heads? is there any difference? i do have a set of TGP heads i can use sitting in my garage. also, i was planning on getting the heads resurfaced....this shouldn't raise compression ratio much/if at all should it?

thanks

[Guest]

The heads are the same as far as I know. Use the better pair.

[geoffinbc]

Yes milling the heads will raise compression. How much depends on how much they are milled. Do not mill them unless they need it. If they are flat then just bolt the things on.

[TurboSedan]

the heads are from my blown TGP engine sitting in my garage, which had a blown headgasket and a melted piston so i just assumed they would need to be resurfaced. i would rather not if i didn't have to; i guess i'll have the machine shop check them for flatness first.

i'll have to determine which heads to use after i get the NA heads off the 'T' engine and have a look at them.

thanks

[malibu97ss]

the heads are from my blown TGP engine sitting in my garage, which had a blown headgasket and a melted piston so i just assumed they would need to be resurfaced. i would rather not if i didn't have to; i guess i'll have the machine shop check them for flatness first.

i'll have to determine which heads to use after i get the NA heads off the 'T' engine and have a look at them.

thanks

joshua, you can do an preliminary job checking the heads by laying them across a pane of glass and checking for warpage by trying to slide a feeler underneath...or just looking may show if there are problems...maybe save a few bucks at the machine shop...

[geoffinbc]

Yup. Um you may be able to find the specs here somewhere. But glass a straight edge (like a good level) or what have you will work. Oh and of course the feeler guages.

[oil pan 4]

More than .006'' warpage and you will need to get them resurfaced.
You use a flat machined edge and a .006'' feeler gauge and try and slide it under the edge.
You slide the edge straight across the head from inside to out side and try and slide the feeler under it.
I use a crafts man level that I bought new and only use it for head checking and very light work. I also have some feelers.

[RebelGT]

VIN T Engines used from 1988-1990 stock head casting numbers: 10048651, 10048696, 14089834
VIN T W/O/SEFI Engines used from 1991-1994 stock head casting number: 10087511
VIN T W/SEFI Engines used from 1993-1994 stock head casting number: 10087511
VIN M Enhanced Engines used from 1993-1995 D-Port stock head casting number: 10154743
VIN M Enhanced Engines used from 1996-1999 D-Port stock head casting number: 24503769
VIN J Special Emissions Spec used in 1999-? stock head casting number: 102181170

VIN V Engine (cast with a ?T? on the block) used in 1989-1990 TGP and TSTE had stock head casting number: 10087511

The stock/NA VIN T engines of 1988-1990 used the 3 different casting heads that all had the smaller designed/more pronounced heart shaped combustion chamber, which was replaced with the 10087511 in 1991-1994 with its more open/less defined heart shaped combustion chamber, then back again for VIN M 1993-1995 and VIN M 1996-1999 with the smaller chamber and more pronounced heart shaped combustion chamber (shuffling the deck a lot!). Changing the piston?s dish volume allowed working with these different heads/combustion chamber volumes, and the 2 different head gasket thicknesses of .040? and .060? to achieve design compression rations for the engine

So, for the 1989-1990 TGP and TSTE, they used the yet unreleased at that time, head casting 10087511 and its larger, less defined heart shaped combustion chamber, with the deep dished 28cc/ml (what Mahle quoted me and I cc?d out of it too) piston top to achieve the .1 drop in compression ratio to 8.8 (or 8.78 depending on what you read)

from w-body.com

[TurboSedan]

well i pulled the 3.1 (and Getrag) out of my Cutlass earlier this week. the heads on it are actually casting #10048696, so i guess the motor was probably built in late '90. the TGP heads i have are casting #10087511 though.

i've had a change of plans though. i found a complete 3400 at a local body shop for $400. it only has 37,000 miles too! i'm hoping i can pick it up in a few weeks. so i've decided to turbocharge the NA 3.1 for now, but i'm going to spend as little money on it as possible....i'm not even going to bother changing the head gaskets. i probably won't even run any boost controller on it; just a vacuum hose from the manifold to the wastegate can (what's that like 5psi?)

thanks for the help! now i just need to figure out what to do with all the GEN-2 stuff i have in my garage

[TurboGTU]

you can give me your gen 2 intake manafolds and heads!

[TurboSedan]

...i'm not even going to bother changing the head gaskets.

well i'm changing the head gaskets anyways. i pulled the '696' heads off my '91 NA 3.1 engine already. the combustion chamber looks quite a bit different than my TGP '511' heads, the '696' chambers just look smaller. could be my imagination though, but they are definately shaped different. i could post a comparison pic if anyone is interested i guess.

well i'm bringing the TGP heads down to the machine shop to get checked for flatness and resurfaced if necessary. i'm also buying GM head gaskets and new head bolts this week.

thanks for the help everyone!