RSM Throttle Body

[whipped]

I sent RSM an email asking about their northstar TB. "Dyno results? Did you really get 14hp from just bolting on this TB? What's the stock TB size?"

Reply:
"72mm"

total bastards. avoided the main reason I sent them an email. Don't worry - I wouldn't have bought from them anyways. almost $400 for a bored TB? not including a $100 core? Yeah, right. :thefinger:

[Aaron]

Stock Northstar throttle body size is 75mm, at least for the 300hp versions it is.

btw, if you want a 75, use that and not the LS1. I learned the hard way that the LS1 TB does not have an integrated IAC valve passage.

[The Dark Side of Will]

OBDI Northstar TB's don't either.

[Aaron]

OBDI Northstar TB's don't either.

Really?

Like how do you mean?

My problem with the LS1 is that the IAC is integrated, but its escape channel isn't, it leads to the back of the throttle body, but not in your intake feed. You have to have a tube welded from the flange on your TB to your intake feed tube. See the pics:

You can see the wleds on the lower right of the pic, right behind that black throttle calbe bracket. That is my tube leading form the IAC passage back to the intake tube. Wheras on the 2.8l throttle body, if I were to bolt it on my 3.4's flange, I wouldn't have to weld in that passage, its integrated.

[The Dark Side of Will]

OBDI Northstars don't use IAC's. They use ISM's (idle speed motor) -- basically a throttle kicker.