In my seemingly never ending quest to a) improve my 3.1 and b) put together the most beautiful V6 engine bay EVER, I have been trying to figure out a way to improve the airflow without attracting the attention of the smog police here in California. Having gasket matched my intake and polished it, I was still frustrated by that sharp bend the airflow has to make to get from the upper to middle plenum manifold, when I suddenly had a revelation and came up with THIS!


These spacers straighten the airflow and ease the transition between the two manifolds, so here is the entire setup, less the middle manifold already installed. * the top part is my hand made coil bracket, complete with 'bowtie' cutout!


Here is a shot of it installed (the ignition wire looms are another mod of mine too).


These are prototypes, but I am willing to sell them as a kit if anyone is interested. The cost will depend on how many orders I can put together, since the CNC initial setup is expensive, so the more folks that want them, the better. Given that this was a first time prototype, how did it work? FREAKIN' AWESOME!! I have not flowbenched them yet, but the car seems- and this will sound strange- LIGHTER. It just gets up and goes quicker, as it it can finally BREATH.

These are 1/2 inch 6061 billet aluminum. At this thickness, the manifold still clears my STB by 1/4 inch. Without the STB, I can run 1 inch spacers and still clear the hood.

If anyone is interested in this ridiculously simple, effective mod, let me know. Keep in mind that I polished these (wetsanded up to 1500 grit them Mother's polished) to match my intake. It makes more economic sense if you want some to get them raw, so you can polish, powdercoat or anodize them to your needs(I may end up anodizing mine red to accent them, but NOT until I pass smog in September!).

Let me know what you think!
*patent pending

 

*Looks like the computer shuffled the photos- sorry about that!! But you get the idea.

Here is a shot from the other side, showing my custom coil mount...

 

im interested. how much to make 1?

 

Really, I need to hit 25 sets to make it financially viable. Let's give it some time and see how many folks are interested. And they don't have to all be the same size either- once the machine is set up, I can cut 1/2 inch OR 1 inch, it doesn't matter.

 

That was going to be my first question! Do you know the part number on the stb? I am looking for one that clears the TB. I want a 3 point brace. And what's the price range on the spacers likely to be?

 

okay. well count me in! and if 25 people dont want it, then let me know how you did it because i have a friend who is a machinist

 

ive done this before it helps out a lil bit, but if u want to get really tick with them have them drilled for direct port nitrous nozzles if somone dosent wat to use nitrous
1/8 inch npt pipe plugs will block the nitrous nozzle holes

 

I thought about the nitrous setup, but I was looking at a streetable setup that wouldn't get me arrested!

 

nitrous wont get u arested u just need to hve the bottle unhooked on the street or get smart and have a lil 5# pound bottle in p lain view with the line disconected.


then stuff a 10# bottle in the spare tire well( the real nitrous bottle ) and u can leave that hooked up ,cops stop u and see the first empty bottle unhooked they wont bother looking for another and ur in the clear

i do belive the lowest u can go with the direct port system was 100 or 150 nitrous shot though

 

I don't suppose you could get dyno numbers.....

I'm in if it works.

 

i can vouch for this mod used to run it on my turbo 2.8 and 3.1 when i used the stock upper manifold

 

That looks really cool. I've thought about how the air has that sharp turn to make before, and this looks like a good solution. I'd be interested in knowing how much of a difference this would make power-wise.

Do the TB coolant lines still reach ok?

If you can make em for under $100 a piece then I'd be in!

 

psst talk to firstfirebird instead of whoever ur using to machine them

 

i'm interested if it makes a difference
give us a rough idea of cost

 

if he talks to jon im pretty sure it will be cheap,

 

it's nice to see a 3.1 plenum all polished up like that. I'd never seen one that nice. I thought about getting one like that and replacing my 2.8 plenum (when and if I ever upgrade to a 3.4, but now I think I'll just find a chevy bowtie emblem to put over the 2.8.

 

Make them out of pheonlic plastic, will lower the cost 2/3s, found most places that sell big sheet, will do deals on scraps that will just end up in the trash big enough to make small items like that, also stops heat transfer and looks like a reg gasket.

not sure a highly polished spacer won't grab attention by someone who looks at engines all day long looking for flaws, they would expect to see a dark colored gasket.

 

I got one half done done / preped for polish I might let lose.
Already spent a few hours filing and sanding down all the casting marks.

 

gumby has the right idea

 

As an ex-CNC machinist, I can say that using multiple scraps is not the way to go, if your looking at the lowest machine time cost.

Cutting 25 out of 1 large plate costs less setup time than cutting 25 out of 25 smaller plates. Or 5 out of smaller plates, etc. Setting X,Y, Z on each piece if they are not all matching would cost more than the cost by just buying 1 large sheet.

 

don't need a CNC to use plastic, a jig saw, a scroll saw, small hole saw, files, any number of ways as it cuts easy.

spare set of intake gasket n a lazy weekend, most anyone could make a set.

A drill press and a cross slide vice can also make things easier.
The original CNC. [HF sells a nice cheap cross slide]

 

Yeah would be better out of phenolic, seen ppl make them with a cutting board, that thick white plastic stuff...

I can't see these making any more power than stock though. Likely lose some top end with the longer runners.

 

How many high speed run do you do a year that an extra 1/2in of runner length is gonna matter???


ever more of a mute point with the speed limiter on most of the line.

 

This is pretty cool, if you talk to some fiero guys on fiero forums you would more than likely get more interest as many have the 2.8 v6 in there and the spacers would work in there. Did you have to mod anything to fit the STB in there?

 

There was one additional spacer needed to elevate the throttle body cable bracket a corresponding amount so it bolts to the top plenum as before, but other than that- straight bolt on. Misses the STB by about a 1/4 inch!
I also don't have the TB coolant lines hooked up, so that was not an issue. In fact, I removed the whole coolant tube assembly from the bottom of the TB. It is just 4 Torx screws I think...
And as to any drop off in top end: it is a V6, not an LSX! And I live in California, so I am lucky to get over 75 mph at any time...

 

I don't mean you'll lose top speed, I mean you'll lose power at the top of the powerband. It will make peak HP lower into the RPM range. The intake runners are already too long for a car (this engine was designed for pickup trucks). So you just made the already too long runners even longer.

 

I'd take a set, PM me if you are making them.

 

lol bring the car over to utah and it will leave with about an extra 120 hp

 

man if these are proven i'd be down for a set as well

 

and which range is that? according to most they don't make any power over 4500 [cause its a truck engine], yet simple breathing mods to one like mine and it pulls hard all the way to redline and ask for more. so ill only be able to red line it then you say? oh the shame

 

I'm in, if you can come to Az and install for me!

 

I had a set of 1/4 spacers identical to this on my car years ago. Maybe the 1/4" just wasn't enough... I ended up making them into flanges for my sheet metal upper intake.

 

I would also be interested.

 

Wake up and smell the wiped cam lobes. Any 60v6 can rev to 6K, it takes real port flow to make power up there. Simply extending the runner length is not going to do that. IIRC a iron head 3.1 makes like 60 HP @ 6K RPM


It's been proven for years that things like this do not improve power. They shift the power band lower by increasing runner length. The only benefit to adding spacers like this is for direct port nitrous. I'll spoil something else for you guys too.. Phenolic spacers are usually worthless as well.



That being said.. drill/tap them for nitrous nozzles and you could have a pretty neat setup for a stock engine.

 

Wouldnt the power band being lower be better for city driving because of torque coming faster? I didnt ask that question well, but I hope its understandable.

 

Yes, it could be felt as that.

With such a small increase in runner length it won't change by more than a few hundred RPM's. More of a placebo effect than anything.

 

Why so searious, Im trying to screw with him to see what he says.



And all I can say is, it doesn't take allot of work to make power up top, just have to open thing up so it can breathe. besides all the goofy stock air ducting, allot of it lies in the exhaust. A straigth shotgun like exhaust is very important. 1 simple 90* turn out is all it took to totally kill all my top end power.

 

I am sure some, like Gumby, will 'poo poo' the whole idea- and the effect may be negligible, by my car seems to be more responsive and less asthmatic with this mod.

 

I think you're kind of a douchebag. I don't like you.

 

Oh snap.

 

If you are interested for sure, send me a PM with what thickness, 1/2 or 1 inch, you would want. I can then figure out a price for everyone. IF YOU WANT IT DRILLED FOR NITROUS FITTINGS, GOD HELP US, mention that too. I can drill it for the fittings for a 'stealth' setup so that it isn't visible in a cursory inspection. It will cost more though...By the way, the vacuum lines and cables all fit fine- the only other mod necessary is a corresponding spacer(I will include that too!) and a longer bolt for the throttle body cable bracket that bolts to the middle plenum. You have to raise that so that the upper part bolts to the top plenum as before.

 

unless you are machining them yourself, I'd suggest looking into having them cut on a water jet. might be cheaper.

 

Gumby, i just prefer to see correct factual information posted.

When people post things like "OMG, I just did xxx and gained xxx power!" with out a shred of actual proof (and against the logic of how engines work), it reflects poorly on the community.

People who don't know any better buy into it then you have a bunch of 2.8 stock iron head engines with Comp 2030 cams, Truleo intakes and shorty headers running around thinking V6's suck because they can't run any faster than a 15.0.

 

^I'd love a 15 flat.

 

14.97 minus the Truleo.

 

add nnnaaawwwzzz itll give you the same as the truleo

 

Pricing available at last!! If you have not already, send me a PM and I will get you a quote!

 

what is the performance gain? and how much?

 

what ever happened with these??? lol

 

I have been away for a while- trying to track down a replacement since my car burned to the ground... send me a PM if you are interested in some.