Interesting. I wonder why GM would put it in at all in that case

 

In your response about the factory UIM insert.... I'm sure they have done some testing that indicates it creates an effect they wanted. Be it something to do with fuel economy, performance, something. Or they felt it was needed and never proved otherwise.....

Here's my UIM with the old insert (hard to see):


And now me tightening the L67 throttle body with the HV3:


More pics here:
'04 Monte Carlo SS - Multiple Mod Install

Another mod to possibly consider (and the guys on the Bonneville forum insist it should be mod #1 on a naturally aspirated 3800) is a port matched lower intake (not to be confused with a gasket matched intake, gasket matching is ONLY good if you also do the heads). I did my own port matched LIM. I actually have another one I plan to do as well and possibly throw it up for sale. Here's a link with explanation and pics of doing my lower intake:
'04 Monte Carlo SS - Port Matched LIM

 

I did the HV3 same time as YT 1.9 rockers so I'm not sure which one gave me the really noticeable power gain. I would assume the rockers mostly but could have been a combination of both items. I wasn't overly impressed with the fit and finish of the HV3. It wasn't a great fit and the UIM gasket needed additional sealer in some locations to provide a solid seal. I use the best parts available whenever possible, so I see a need for ZZP to make an HV4. Or perhaps they need to build a completely new UIM like manufacturers do for GM LS engines. I would buy a complete UIM rather than dicking around with adapters and spacers for northstar TB's to fit. Wouldn't be hard either, if dorman can make parts that fit anyone can do it.

 

@Justin Knight - By chance do you have an aftermarket replacement UIM? If so, I have heard the HV3 does not fit right in the non-OEM replacement UIMs.

Also, ZZP has 2 different HV3s. One for the plastic UIM and the other for the aluminum UIM. I had bought in my hands at one point. They are slightly different.

I had no issue fitting mine in. But, without knowing their molding practice, it's tough to say if there are a few one-off issues.

 

i like the idea of a custom intake manifold for these cars... sounds like ZZP should take up this project. if dont right it would be great for both NA and Turbo!! i would say they should go as far as making an entire lower replacement!! one piece just bolt in the new lower and call it a day. maybe have a separate valley cover like some high rise lower intakes for the V8's! i always liked how my DOHC's lower intake was not touching the valley floor. kept things cool and allowed a better angle for the runners.

 

Here's something interesting. The N/A versions of the old 3.8Ls put out around 130-140hp in the mid 80s and (from what few numbers I can find) around 200 ft-lbs of torque. They obviously considerably lengthened the runners when by the time they got to the Series II motors because torque only went up 25 or so but HP went up to 200 for the N/A applications. The turbo versions in the Grand Nationals put out 245/355 and for the GNX 275/365 (it is said that Buick vastly underrated the numbers for both the GN and GNX). It had V8 style runners (which at the time shot for more torque than hp). This is why I want to do a RWD turbo project with the modern 3800 motors. I'm curious as to what can be done. A good chunk more of the power would make it to the wheels if I used a manual so it would probably dyno better than the FWD turbo builds that some have done. The RWD L36 used a different UIM as well. Not sure if the runner length was different than the FWD version though, but the RWD L36 appears to be more of the LT1 style which has a very broad torque curve compared to the L98 TPI motors.

I'm kinda just thinking out loud, but something I may have to look into. I may have to pick up intake manifolds for each from a salvage yard when I have a few extra bucks and takes some measurements.

I personally don't like motors that require you to rev real high to get power. I never really liked the 302 in the 67-69 Z28s for that reason. I love that low to mid-range torque (2000-4000 RPM) that you get out of most of your small blocks and the 3800 motors.

 

@SupplySgt - As for the F-body RWD L36, the UIM and LIM are different. Not sure how much it makes a difference, but the ports in the LIM to allow air to flow into the head ar more tear drop shaped then the FWD LIM (which are square-ish).

But I see where you're going. Turbo a F-Body L36 and I bet you would not be disappointed.

 

That's EXACTLY where I'm going with it. I've been thinking about this (as well as a RWD L67) for quite a while. Mate either one up with a manual transmission and I could have a lot of fun with them. Like I said, I probably need to pick up a set of each and start taking measurements and compare everything.

 

Just wanted to show you what some local friend are doing on a turbo Grand Prix build since we're talking about intakes.

 

what the heck did that intake come off of?