ok, i pretty much decided im gonna go with the LS6 on my LQ4. but now i need to know what thottle body to get, i cant find anything that says what size it takes, or the best brand. im gonna do a cam and some head work too so i would think the bigger the better. and also what fuel rails to use.

 

STOCK IS 75MM, i went with an 80mm which came with a spacer that reduced to match the opening. because of the spacer i couldnt fit my bellows and had to use the stock flexible rubber piece. another issue / easy fix is the throttle cable length has to be adjusted by uncoupling the cable and letting it self adjust then reconnect. its about halfway back on the cable. cheers!

 

Most people just have someone port it to 90mm. There are a couple sponsors on site that do this.

 

You can buy a ported/polished stock TB- which BTW I have one for sale... but you cannot port the stock to 90mm.

Those 90mm TB's are aftermarket-- they are huge and you need to work out a way to plumb them after the change. (You need a 4" boot).

 

^Agreed with above. The stock TB cannot be ported to 90. It's just a "ported" stock TB. And, that's what I would go with on an LS6 intake. If you have a mild-ish street cam, IMO, the LS6 intake is the way to go. If you're throwing a 23x-24x cam and heads on there, FAST 90/90 intake/TB is another option. I have a 225/229 cam and LS6 heads/intake/ported stock TB on my 5.7L.

If your TB is too big, you risk losing low end for very little higher-RPM gainst.

 

Interesting; makes sense and I had never thought of that.