TB and Intake manifold questions

**Netskimmer** · 04-20-2009, 10:57 AM

I was swapping out my stock intake for a K&N system for some reason I decided to measur the TB. My calipers show about 80mm for the inside diameter at the lip, I don't know how you measure them exactly, would this mean that the TB is 80mm? What is the size of a stock TB? Not sure what the previous owners have done to it so I'm curious. I would also like to know how to tell an ls1 intake manifold from an ls6 manifold without removing it. I have included some pics of my new intake and the TB.

**Orcus79** · 04-20-2009, 11:12 AM

Looks like a stock TB, and the the biggest diferance between an LS6 intake and the LS1 is the EGR tube that stares you in the face on the LS1 intake. It's not there on the LS6 ones.

**ntimid8r7** · 04-20-2009, 11:16 AM

LS6 intakes do not have the EGR port and also the part number which is on the passenger side in the middle on the flat part of the intake if I remember correctly. I don't know the number off the top of my head but all 98-00 Fbodies have the LS1 intake. From the looks of it nothing has been done to it. You have the LS1 intake.

**ntimid8r7** · 04-20-2009, 11:18 AM

hah you beat me to it..

**Netskimmer** · 04-20-2009, 11:31 AM

So what size is it? Would getting a larger TB without swapping the intake manifold do me any good?

**Orcus79** · 04-20-2009, 11:34 AM

Nope, getting a larger TB wont do a thing with the smaller intake, and 80mm is about right for a stocker.

**thearborbarber** · 04-20-2009, 11:37 AM

78mm is a stock throttle body

**Orcus79** · 04-20-2009, 11:40 AM

Ahh, my bad, though 80 would still be in the range of error for a mass produced product.

**Netskimmer** · 04-20-2009, 11:53 AM

How difficult is it to swap out intake manifolds? It doesn't look easy. Would a larger manifold and tb be worth the time, effort and money for a daily driver that isn't raced?

**Orcus79** · 04-20-2009, 11:59 AM

It could be, and its not as hard as it looks, just a bit more involved since you have EGR and will have to remove it. You should a get tune for it if you go larger to maximize the gains, and with removing the EGR you will need one any ways to remove the codes.

**Hi-Po** · 04-20-2009, 12:34 PM

LS1 intake part number is 12560688

LS6 intake part number is 12561184.

A intake manifold swap is very easy. Basic hand tools, and being careful not to hit the oil pressure sending unit is all it takes. Tune is not necessary for a intake swap, but it would help squeeze it for the extra HP.

**shady milkman** · 04-20-2009, 12:39 PM

Originally Posted by thearborbarber

78mm is a stock throttle body

75mm actually ..but not like it matters

**thearborbarber** · 04-20-2009, 12:58 PM

Originally Posted by shady milkman

75mm actually ..but not like it matters

3rd time is the charm.

**shady milkman** · 04-20-2009, 01:00 PM

Originally Posted by thearborbarber

3rd time is the charm.

huh?

**thearborbarber** · 04-20-2009, 02:58 PM

The third answer was correct.

**Cutlass** · 04-20-2009, 04:52 PM

Originally Posted by Netskimmer

My calipers show about 80mm for the inside diameter at the lip, I don't know how you measure them exactly, would this mean that the TB is 80mm? What is the size of a stock TB?

You'd have to take the 'butterfly' blade out of the TB and measure it. I've done that and it is indeed 75mm. The opening at the lip is bigger than it necks down to the blade.

Originally Posted by Netskimmer

How difficult is it to swap out intake manifolds? It doesn't look easy. Would a larger manifold and tb be worth the time, effort and money for a daily driver that isn't raced?

Its not super difficult. If you gonna do something, I recommend the LS6 intake, a ported and polished TB (Shaner S3 maybe), and a Mail Order Tune so the SES light doesn't come on since the LS6 intake doesn't have a EGR hook up. Details on all those mods should be easy to find with a little searching on this site or Google.