Write-Up: 4" FWI Spectre Intake for Northstar (N*) Throttle Body+ LQ4 MAF

This is a mildly involved and not very economical solution to making a good true 4" intake system to be used on rivieras modded with a northstar throttle body and LQ4/LS6 maf sensor.

One great thing about this setup is that it is ever-modular and could be changed with the addition of other modifications such as an intercooler. You could also use it on another car if so desired. Another plus is that it's built out of parts actually meant for automotive intakes so you can imagine the benfits there.

Downside is the way I'm doing it myself and the writeup anyway, it requires changing the coolant overflow bottle and opening up the fenderwell hole (which would be required with any 4" FWI).

To start off, here's what my fendewell passage looks like opened up for easy fit of 4" pipe.










from the bottem




with extended spectre 4" filter installed (I used a standard size filter because this one was too tight of a fit to let me angle the pipe the way I needed to)

I cut the 3 outter sides of the passage out about a pinky each with a dremel. It took me about 2 1.5" cutting discs to do it and then i filed the edges by hand just to smooth it a little bit. I used U-style black door edge trim to line the edges with mainly to keep from scratching the new piping going through it and make it look a little nicer.



to be continued soon...

Glad to see a write-up on this. How about a parts list?

That pic right there shows you what the special sleeve does for you on the maf sensor. It's thicker so it takes up the space in the coupler and effectively cancels the annoying notch thats on the housing.

looks cute..

Part numbers in order of installed location (all part numbers are Spectre parts)

*northstar TB
*9771 coupler (with included sleeve on the TB side)
*9709 4" long pipe
*9771 coupler (with included sleeve on maf side if you skip the special sleeve, part number 990003 for the special sleeve if you use it)
*LQ4/LS6/etc maf sensor assembly
*9771 coupler (no sleeve required)
*9749 45 degree pipe
*9771 coupler (no sleeve)
*9709 4" long pipe
*9781 90 degree silicone elbow
*9719 6" long pipe
*8138 air filter (that I used)

Again, the special GM-specific maf sensor sleeve (990003) that Spectre makes is optional. It really doesn't make the install any easier or better, funtionally. It just looks a little tiny bit better if you're picky.

The filter you use is really up to you. If you already have a 4" fit K&N or something else that looks about the same size, there's no reason not to use it.

You must move or remove the OEM coolant overflow bottle in order to use this exact intake setup. I've tried different things puzzeling around with pieces and it seems like it would be near impossible to do this without modifying individual pieces. Once you get a feel for how much it costs for all these parts, you probably won't want to be cuting them... Installing an aftermarket overflow bottle is not much of a hassel. It's just one hose and then figuring out a mounting solution. Some creativity with a few long zipties did the job very well for me. Make sure that the tank is vented since the factory tank is vented. It will not work properly if it is sealed.

i noticed the filter things stickin out of 2 of ur looks like oil and collant areas...do those make a difference?

Nice parts detail, thanks for that and the pics. Good job!

xxsupergman25xx wrote:

i noticed the filter things stickin out of 2 of ur looks like oil and collant areas...do those make a difference?

The oil breather is necessary to use a northstar throttle body with ZZP's adaptor as is because the adaptor blocks off the PCV inlet. You can also drill that piece of the adaptor and use it like the original setup but the experienced 3800 tuners say that it's better to run a breather with moderate to heavy mods anyway because the factory PCV system may have trouble "keeping up".

The smallest breather on my coolant tank is just my method of venting it. The factory tank has a vented cap. Under normal circumstances, air should be the only thing moving in and out of the vent, if that. If you want to, you could also run a hose from the top vent port of the new tank and route it to the ground somewhere so if for any reason, it overfills (possibly from overheating, overfilling, not burped, etc), the coolant can come out without making a mess under the hood.

Very clean install. Totally custom and one of the best options w/out cutting and welding your own stainless steel tubing!Most of us aren't tig welding SS in our garages and polishing it to show quality like these pieces.Good write-up I would like to have that set-up for sure.

Turtleman,
Maybe you should put a price together for all pieces and shipping for the people that want that set-up.
You can get all that together and make a kit for everybody interested. You work where you can all the pieces don't you.?

Rickw wrote:

Turtleman,
Maybe you should put a price together for all pieces and shipping for the people that want that set-up.
You can get all that together and make a kit for everybody interested. You work where you can all the pieces don't you.?

Although that would be convenient.. This set-up with the same parts HE has wouldn't work for you.. it would want to go into your coolant tank like 4 inches.. Goood idea though

I've looked at a lot of FWI designs, and my favorite would have to be that of J. Chris Davis. He chose to build an aluminum FWI system using parts from Spectre performance, and I really love the way it shines under the hood. However, I'm concerned about the clearance issues some 96 owners have stated about their coolant tank. Apparently its a different design or in a slightly different location than the 97-99s? Anyways, I want to know if this system is going to work. Or will I have to modify his setup? Thanks.



Link to Chris's Spectre FWI is https://rivperformance.editboard.com/t7418p30-my-98-buick-riviera

J.Chris Davis's Spectre FWI build:

Only took a couple of hours since after all the pics and reading on here it went rather easily. First the parts I used were spectre 3.5" aluminum. So it went like this: 4" to 3.5" reducer, 45 degree, 3.5" coupler, 22 degree, 3.5" coupler, 90 degree, 3.5" to 3" reducer, 3" diameter 6" straight into the filter. Part numbers I used were 9741, 9541, 9549, 9529, 9599, 9419, (2) 9571 and the E-0774 K&N Filter.

AA, do you know anything about the difference in the coolant tank locations?

I don't know for sure. I thought they were the same or close. Can you take a picture of yours?

Yeah I'll try to get one. Let me go run out to my car.

It's a pretty tight fit right now with the stock setup. Is this how it is on the 97-99s?

Looks the same to me.

I have no idea why it posted four of the same pictures. I actually posted 4 different images.

AA, what is the piping diameter for your FWI?

3.5"

Is it also 3.5" where the piping goes through the hole for the stock air box? Or did you have to taper down to 3.0"?

If it is 3.5", did that require you to cut into the metal and make the hole bigger? I'm trying to figure out if I need to taper down from 3.5" to 3.0" after the 90 degree angle. I'd rather go 3.5", but I'm not crazy about cutting into the metal.

Mine tapers down right before the hole. But cutting the metal isn't a big deal, as long as you paint the edges so it doesn't rust. If you ever want to go back to stock, no one will ever know.

I'm literally about to order this:
http://shop.zzperformance.com/store/p/1038-4-Fenderwell-Intake.aspx
what issues do you foresee with this on the Riviera?? the only thing that I can think of is maybe it not clearing the coolant tank. the application list for the intake is a vague " 97-03 series 2" but we all know nothing on the 96' would change the fitment of this.

i dont think it will work at all for the riv. its designed for the gtp and ssei i believe