Pictures of early 3.4 dohc intake?

[vinny]

Hey guys, Im' just sitting here at work and I got to thinking about the intake on my 92' DOHC. This engine will be rebuilt sometime next year and I haven't looked at it in a while. Is the intake a 2 piece unit? Upper and lower unit?Anybody got any pictures of one? If the unit has a lower plenum that has a flat surface you could possibly use one of these upper plenums to make a smaller custom intake using yours. http://www.rossmachineracing.com . Sence I can't seem to remember what the specifics are of the intake I figured I would ask the experts.

Thanks as always guys

Vinny

[RedZMonte]

the upper and lower is seporate pieces. it does have a flat surface so you could build a custom upper intake... honestly it would be alot of work with little gains unless you have a turbo/Supercharger.

Alot of guys do a 1996-97 upper and lower intake swap, cheap and easy.

S

[ez112]

I agree with RedZ. Unless you went Forced Induction, the effort would be on minimal value. You might even be looking into hood clearance issues?

[vinny]

Well I'm looking for asthetics and maybe forced induction later.

Thanks guys
Vinny

[RedZMonte]

Im boosting threw my stock intake manifold. the 1996+ will give better flow but makes changing the rear plugs a biatch. you have to remove it to change them where as the 1991-1995 intake you can change them without removing them..

you will LOSE alot of TQ down low if you have to short or too large of runners. it will have to be something custom made and i will tell you it will have to take a few attempts to make them the correct lenth and runner size. the 1996 lower intake has all 6 ports in a straight row where as the 1991-95 lower intake has then staggered. the '96 intake would be the best bet for ease of building a custom intake... AGAIN not worth the trouble just for astetics.

I would recommend just stripping the stock powder coating and painting it or custom powdercoating it would be the easiest and most headache free/cheapest way to make it.

Like So (hayesperformance):


S

[HayesPerformance]

I was impressed with the results I got from my 91' intake (shown above) and what I did was comlpetely port and polished it, Being very careful not to make the ports larger, I port matched the LIM and UIM made the gasket match too, bored the TB to 72mm, bell shaped it and polished smooth. I even port matched AND port and polished the inside of the new manifolds before ceramic coating them. I have a good oil catch can before my PCV so that my Port & Polished, UIM, LIM, and heads don't get all full of crap over time. I'm glade I did it cause it work VERY well, the inside of my intake is STILL clean.

I found that I gained a lot in making sure I put alot of time into the heads, 96' heads of course.

[timg]

If you want to build a new manifold, the 96-97 lower intake manifold is probably a better starting point. The 95 would require quite a bit of extra effort- the ports are offset a bit. On the 96-97, they are in a straight line.

Tim

[RedZMonte]

here is what the lower intake from a 1996-97 looks like... The 1991-95 again looks simmilar but the ports are staggered.

http://i72.photobucket.com/albums/i166/dave96z34/lowertestpice004.jpg

S

[timg]

Hey, nice flange!

Tim

[series8217]

you will LOSE alot of TQ down low if you have to short or too large of runners. it will have to be something custom made and i will tell you it will have to take a few attempts to make them the correct lenth and runner size. [...] ... AGAIN not worth the trouble just for astetics.

These things you say, they are not true! How about doing some research first? I posted my dyno graph on this forum a few times... I definitely have plenty of torque with my short runner intake, and gained top end over a stock DOHC as well. It also only took one attempt and a single weekend from car running to car running again with new intake.
I have 200+ ft lbs from 2200 to 5500 RPM with my short runner custom intake. Stock cam timing. The dyno graph is right here:


Apparently the stock 91-95 UIM flows so poorly that even a short runner UIM has better low end torque. I have no experience with the 96-97 intake but I haven't heard about torque down low like this:

It flows better. It was easy to make. It was inexpensive to make. It looks hot. Spark plug access is greatly improved. It even provides for some weight reduction. Sounds great too. Also check out the improved powerband! I highly recommend it.




You will need a TIG welder, a big bandsaw or hacksaw (and patience if using the latter), a nice piece of 3" pipe, and a weekend. I just cut up the stock upper intake and welded the pipe in. The throttle body is in the stock location. Make sure to disassemble it too so you dont fry the bearings and/or warp the blade.


Didn't take any pics while building it, sorry. I disassembled the TB, chopped the stock plenum off (left a bit of metal connecting the throttle body still), cut a side out of the pipe, welded it on, welded an endplate on, then ground down the welds and smoothed them out, drilled and tapped some holes for vacuum fittings, applied some paint, and voila.

The TB warped a bit from the welding so the throttle body coolant passage no longer sealed; I just ground the UIM coolant passage away a bit and put a blockoff plate on the LIM. With some silicone it probably would've sealed, but this is easier to deal with; I can pop the UIM off in a couple minutes and not worry about spilling coolant (yet another advantage!).

[RedZMonte]

i know i have spoke to 2 or 3 DOHC guys that have made custom upper intake manifolds and allways gained high rpm hp but allways lost torque. General rule of thumb short runners gain peak HP and long runners gain low TQ. im not saying you cant make one that gains both, im saying it has to be more then random lenth/random size runners and the opening in the plenum should be a certin volume depending on then engine. Im glad to hear your custom setup worked well... so far that 1 of 3 i know of.

here is matt hawkins custom short runner intake... Notice the large volume of his intake... and he didn't just hack and guess at the intake runner size and lenth for his to make power...


here is the old posts i was thinking of.

http://fiero.cc/fiero-tdc/members/mws/intake/index.html

S

[vinny]

Does anyone have a picture of the inside of Matt Hawkins intake box? Just wondering how he put it together. A little experimentation here and there! Fun project.

Vinny

[pocket-rocket]

I remember that 2nd one. And if I remember the torque curve right, it looked like the equivalent of sitting still and getting rear ended by a Mack truck at about 5k-8k.