Porting intake

[RallyBob]

Originally Posted by Paul On a more serious note... By this, I presume you form up a sheet of Aluminum into the peak shape and height you desire... What works better a sharp or rounded peak? What thickness is the material you weld back in? And, how carefully do you blend in the peak's material with that of the floor and adjoining walls... Thanks....

Well, just like everything else in life, there's no set answer. I'm constantly evolving my intakes, so they are ever changing. Most recently, I make the 'tent' from two separate pieces of aluminum, and weld them at the peak. This leaves a blunted top edge, rather than a sharp edge. I make them from .080" material these days, although I've tried both .063" and .125" thick.

The .063" is a bit tougher to weld to the thicker intake material, while the .125" is easier to weld but tougher to cut and shape to fit. The .080" is a nice compromise.

I weld the material from the underside, so there is no blending inside the plenum at all really. When I used to pay to have someone weld the 'tents' in place, it was from the inside. But this was time consuming and very costly, although it made the inside look nicer. Performance wise? I have seen no difference.

My next intake project (for me, not for sale!) is a fully fabricated intake from scratch, with hammer-formed runners that are .063" thick, and with a fully hand-shaped plenum. I suspect it will weigh about 1/2 what a stock intake weighs, and I can finally remove the OEM tight curves of the stock intake, as well as enlarge the runners consistently. It will have to sit a bit higher than stock too, so it won't fit under a GT hood. I'm guessing about 12 hours of labor to actually fabricate it, but I've already started making my hardwood hammerforms for it.

Bob

[2 Fast 4 U]

Originally Posted by RallyBob My next intake project (for me, not for sale!) is a fully fabricated intake from scratch, with hammer-formed runners that are .063" thick, and with a fully hand-shaped plenum. I suspect it will weigh about 1/2 what a stock intake weighs, and I can finally remove the OEM tight curves of the stock intake, as well as enlarge the runners consistantly. It will have to sit a bit higher than stock too, so it won't fit under a GT hood. I'm guessing about 12 hours of labor to actually fabricate it, but I've already started making my hardwood hammerforms for it. Bob

Are we going to see any photo's as you make the intake??

[RallyBob]

Originally Posted by 2 Fast 4 U Are we going to see any photo's as you make the intake??

Nope. I still don't have a new digital camera. And very soon, once my family sells their business, I won't access to a computer anymore either, not until I can afford to buy a new one. So you won't hear from me for a few months at least I think.

Bob

[RallyBob]

This is again a bit off-tangent, but it shows my priorities regardless.

No, I won't buy myself a new computer unless I have the cash for it. But, I did just order a new Garrett ball bearing GT2554 turbocharger on my credit card. I am going to build that Opel turbo 'kit' after all, and will prototype on my own car. Basically I will just build a manifold that fits the Manta/Ascona chassis, and will create an instruction sheet to build the rest of the system yourself. Opel owners are, uh, frugal, and wouldn't spend the necessary $3500-4000 up front to built a kit correctly, so if I supply the hardest part (the manifold) the rest of the components can be built up over time without breaking the bank. This project holds more value to me than buying a computer.

A GT chassis is too difficult to fit unless you do some cutting to the engine crossmember and relocate the engine mount. Not enough room to fit it efficiently, and without 'cooking' adjacent components. Not that it couldn't be done, but it wouldn't be 'bolt on'.

Bob

[Hiro]

Originally Posted by RallyBob I am going to build that Opel turbo 'kit' after all, and will prototype on my own car. Basically I will just build a manifold that fits the Manta/Ascona chassis, and will create an instruction sheet to build the rest of the system yourself. Opel owners are, uh, frugal, and wouldn't spend the necessary $3500-4000 up front to built a kit correctly, so if I supply the hardest part (the manifold) the rest of the components can be built up over time without breaking the bank. This project holds more value to me than buying a computer. Bob

that's another super news Bob!
I recently purchased a MantaA,
so I'll be glad to buy your turbo manifold!
Hiro

[thescifiguy]

I'm in the final stages of the RallyBob intake manifold modifications and I've got some questions:
1) With a "tent" across the bottom, welded or JB Welded in, what do you do about the vacuum advance hole at the bottom? Do you reposition it above the brake booster? Can I put a T-fitting in the booster line for the vac advance?
2) With a stock '72 GT 1.9 with mileage, 32/36 weber, elec. ignition, headers, and free-flowing exhaust, what would you guys recommend, as a starting point, for jetting sizes for the carb?
3) Would a 1/4" spacer block be beneficial, or recommended, for normal street use of the car?

The story of my intake mod project:
I didn't want to incur the problems of warping due to welding the bottom plate back on, so I decided to make a wedge-like affair and use JB Weld to hold and blend it in. I couldn't find an appropriate billet of aluminum to machine down, plus a one piece design with decent height, with a base about as wide as the bottom of the plenum, would be difficult to insert inside. I used a piece of 1/4" thick x 2" aluminum angle "iron" that I cut down to 1 1/4" wide sides and the whole thing about 3" long. The diagonal from side to side is 1 1/2", which is about the width of the bottom of the plenum. I squished it in a vice as best I could to steepen the angle some before I cut it. My little tent sticks up about 1 1/8" from the bottom. Nice, but I wanted more height, so I cut out a bar of aluminum that is 1/4" x 1" x 3", inverted my tent, drilled two 1/8" inch holes through the peak of the tent, then into the aluminum bar, so that the holes match up. I pounded 1/8" x 1" roll pins into the tent so that they stuck up from the peak about 1/2". Now my bar can be mounted sticking straight up from the peak of the tent. In cross section, it looks like like an upside down letter Y. This design allows me to drop the angle part into the plenum and gives me room to weld or JB Weld the base in, then I can tap the vertically oriented bar onto the roll pin posts. The joint from the vertical bar to the tent sides can then be welded or blended to smooth the transition.

I'll take pics to post in my next entry.

[thescifiguy]

Here's the pics of my Y-shaped intake insert. Sorry for the picture quality. Put together, it's too large to jiggle and wiggle into the carb opening, so I came up with a 2-piece design that assembles INSIDE the plenum. In the last pic, it's been assembled inside the plenum, but it hasn't been welded/epoxied or blended in.

If this works, it's an inexpensive alternative for those of us without access to milling machines or who don't want to get quite so radical as cutting off the bottom of the plenum and risking welding warpage. I just used cheap 2" long Ace Hardware reaming tips and grinding stones on a 6" drill extender.

http://www.opelgt.com/photos/showgal.../23478/cat/500

[thescifiguy]

Delete

[thescifiguy]

I've finished the plenum area of my RallyBob intake manifold modification. I decided to use JB Weld for all the blending and attachment. It took about 8 applications and about a tube and a half of each of the tubes of the product. JB Weld flows very slowly to the lowest point, so I had to do a separate application for each angle or plane that I was going seal, attach, or blend. It self-levels very well, so little boogers sticking up slowly sink away and vanish

It was very difficult to apply the thick gooey stuff in such a tight area. I had to clamp razor blades with needlenose vice grips, shovel some goo on one, angle it carefully inside, then use another clamped razor, wiggled inside the opening, to scrape the epoxy off the other razor onto the area being worked on. Luckily, the fact that the stuff takes about 6 hours to even get firm gave me plenty of time to work it around with screw driver tips and stuff. Clean up was real easy. Excess wiped off easily and it washed off the fingers with ease, too.

My "divider" stops about 3/4" from the carb opening, so I had to move the brake booster and crankcase vent tubes. I replaced them entirely with thick gage stainless steel tubing, flared on the ends, one 1/2" and the other about 5/16". I left the brake booster one extra long so that it's a little easier to install the hose on it in the car. I moved the crank case vent tube to the engine side of the manifold. Now I'll only have to use about 5-6" of hose to connect the manifold to the small valve cover vent hole and it will run in almost a straight line.

All in all, I'm very satisfied with the concept and I'd do it again the same way. I would probably spend less time grinding away at the manifold to eliminate the bumps and divots. Most of them get covered up with the divider modification anyway.

The last 3 pics are the latest. This is the link:

http://www.opelgt.com/photos/showgal.../23478/cat/500

[Geek]

I'm kind of surprised that this hasn't come up yet, but aren't you afraid that the JB weld will deteriorate and find it's way into the engine? Yhere was another member here who built the entire divider thingy with JB weld, and when he tore it down again, he found that some pieces had been lost while in operation. It should come up if you do a search.

[thescifiguy]

You're right, pieces coming off is definitely a concern. That's why I opted to only use JB Weld for the joints and attachment. 90% of my flow divider is aluminum and the only JB'd areas that will have any serious air flow directed at them is the 3/8" or so strip, in front of the individual port openings, that blends/attaches the wedge to the bottom of the plenum. I did this more as an experiment for the average Joe who doesn't have access to milling machines and skilled aluminum welders. I also think that the risk of warping due to welding is an absolutely unacceptable risk. Opels have enough problems with vacuum leaks to add a warped intake to the list. My modification can be accomplished by ANY minimally skilled home mechanic.

As far as junk getting in the engine, well, it's just a personal opinion, but, I think people worry way too much about that sort of thing. Sure, dropping a nut or a bolt into your carb is bad news, but if it's small enough to get past the valves INTO the engine, it's small enough to get OUT. I used to hang out at a friend's junkyard and at one time we decided to drop things into the carb of a junker to see what would happen. Nuts, bolts, ball bearings, bugs, sand, metal filings, paper, even flour we dropped in several cars. It all came out the exhaust pipe. Sometimes spectacularly! Flour was real fun. A huge ball of flame came out!

Considering all the vacuum hose leaks sucking leaves and dirt in, decomposing foam dome air cleaners, and the hair filled air filters I've seen on Opels and other cars, I'm not worried about the possibility of a couple teeny little hard pieces of epoxy blowing through. An engine isn't a stomach, it's more like a vacuum cleaner.

Only time will tell. Wish me luck!

[hrcollinsjr]

Originally Posted by thescifiguy Sure, dropping a nut or a bolt into your carb is bad news, but if it's small enough to get past the valves INTO the engine, it's small enough to get OUT.

I've seen the results of a nut or washer dropped in the carb at a racetrack. Hmmm, wonder how that happened? Anyway the piston and valves didn't fare too well. It bounced around awhile before it found it's way out.

Harold

[hrcollinsjr]

Originally Posted by thescifiguy Considering all the vacuum hose leaks sucking leaves and dirt in, decomposing foam dome air cleaners, and the hair filled air filters I've seen on Opels and other cars, I'm not worried about the possibility of a couple teeny little hard pieces of epoxy blowing through. An engine isn't a stomach, it's more like a vacuum cleaner.

Also have a Country Clipper ZTR mower with a $1000 Kohler engine ruined after one season of mowing because the air filter was loose and we didn't discover it until it was too late.

Harold

[Gumby]

Originally Posted by thescifiguy Considering all the vacuum hose leaks sucking leaves and dirt in, decomposing foam dome air cleaners, and the hair filled air filters I've seen on Opels and other cars, I'm not worried about the possibility of a couple teeny little hard pieces of epoxy blowing through. An engine isn't a stomach, it's more like a vacuum cleaner. Only time will tell. Wish me luck!

O_o

Most high temperature epoxies have a Shore hardness in the 70 - 90 range (aprox 15 - 20 Brinell hardness). So it is probably safe to assume that it is not likely to "destroy" the engine if a small amount makes it through the intake. But consider that even though epoxies are less than half the hardness of machinable grade steels (ie soft steels, no heat treatment) it is still a hell of a lot more abrasive than air and fuel. Like I said it isn't likely to kill the engine but I can almost guarantee that it will cause undue wear on it.

If you are looking for a custom intake manifold PM me. Once I have my mill running again I plan on making one (maybe two) for my own GT.