Sportwagon from hell...header pics

[RallyBob]

I thought this might interest some of you. Thinking outside the box as usual, I built a custom 1.625" x 32" long equal length 4>1 header which is routed completely above the inner fender, rather than along side the block. This enabled me to NOT have to modify the floorpan to fit the merge collector over the sway bar (a common issue with model 50 Opels). BTW, the merge collector is 6" long, tapering to 2.125", and then another 6" tapering back up to 2.5". I used a v-band clamp so I don't have to deal with nuts/bolts/gaskets.

I also have fitted 3 mufflers to the car in keeping with the stealth mode. So even though the exhaust is 2.5" front to rear, the car will be quiet. This was made easier by the fact that the car is a 1975 California-spec car, so it has a floorpan recession at the passenger seat area for a catalytic converter. I used this area for the first 14" long Magnaflow muffler.

It is all fitted to the 2.5 litre roller cam prototype engine, and is getting ready to accept the cut-down 3.0 litre 6-cylinder EFI intake (cut down to 4 cylinders) and programmable EFI. Should be fun...

Bob

[RallyBob]

More header pics.

[RallyBob]

Exhaust pics.

[RallyBob]

Low-profile over-axle pipe. Only 2" tall, but added 2" to the width for greater flow in this restrictive area. It flows like a 3.375" tube basically. Quite a lot of work, but it had to clear the swaybar, the panhard bar, and the rear axle as the car is lowered from stock.

[neuropel]

That's looking mean. Is the car going to have a PAINTED hood?

Todd

[RallyBob]

In order to allow the 2.5" main pipe to travel under the torque tube crossmember but not drag on the ground everywhere, I modified the crosmember by notching it and reinforcing the top area. I *just* had to tap the floorpan a bit to clearance it, but not a big deal and it allowed me to raise the exhaust clearance by almost 1.5"

[RallyBob]

Originally Posted by neuropel That's looking mean. Is the car going to have a PAINTED hood? Todd

Don't worry, it's getting the 1700 degree Jet-Hot coating on the header! It reduces radiated temps by 300-400° F.

[namba209]

Fantastic workmanship as usual Bob. I really hate to ask, but will you have clearance when the engine torques to the right under acceleration? I was concerned with the same when I did the exhaust on Willit? I only had about an inch between the down tubes and frame rail, but really solid rubber mounts limits torque movement. With the softer mounts standard on the Opel, I'm a bit concerned.

[RallyBob]

Originally Posted by namba209 Fantastic workmanship as usual Bob. I really hate to ask, but will you have clearance when the engine torques to the right under acceleration? I was concerned with the same when I did the exhaust on Willit? I only had about an inch between the down tubes and frame rail, but really solid rubber mounts limits torque movement. With the softer mounts standard on the Opel, I'm a bit concerned.

Yes, in fact I'll have more room when it's done. Someone who worked on the car in the past decided that an Opel engine needed to be level rather than tilted as the factory designed it, and shimmed the driver's side engine mount up by 3/8". When I lower it back to stock the passenger side clearance will open up. That, and I have polyurethane mounts to be installed yet, and they are MUCHO stiffer than OEM.

Bob

The mounts are GM tranny mounts I modified to fit BTW, like this.

[broszzy]

Yes nice work Bob. looks like you only tig on that wood welding table? LOL

[BQS4]

GEEZ Bob, this makes the exhaust work I just had done look like crap. Can I get you to redo it? Seriously though, awesome work as usual Bob. Is the pipe material stainless steel?

[RallyBob]

Oh, and those of you with 50-series car might want to check those lower a-arms once in a while. This car had a crack right through the inner pivot bushing sleeve. It drove nasty down the road...

[RallyBob]

Originally Posted by broszzy Yes nice work Bob. looks like you only tig on that wood welding table? LOL

I actually just bought a steel plate for my welding table last week. 4' x 8' x 3/8" thick steel! I welded the collector and the crossmember balanced on a vise....

[RallyBob]

Originally Posted by BQS4 GEEZ Bob, this makes the exhaust work I just had done look like crap. Can I get you to redo it? Seriously though, awesome work as usual Bob. Is the pipe material stainless steel?

The header is mild steel as it's being coated inside/outside by Jet-Hot. The exhaust system and mufflers are T304 stainless, yes. BTW, the new (non-polished) Magnaflow stainless mufflers are downright affordable. Not worth buying plain steel mufflers IMO!

[heimue]

Originally Posted by RallyBob I thought this might interest some of you. Thinking outside the box as usual, I built a custom 1.625" x 32" long equal length 4>1 header ... Bob

This is freakin' awesome! For those of us who want to learn from the Opel God, what is the best way to ensure that all the header pipes are equal in length, besides designing them in 3D CAD? What is an acceptable length tolerance (in percentage from the nominal length) to still consider all pipes an equal length, e.g. for a turbocharger setup?

Dieter

[RallyBob]

Originally Posted by heimue This is freakin' awesome! For those of us who want to learn from the Opel God, what is the best way to ensure that all the header pipes are equal in length, besides designing them in 3D CAD?

I am so non-high tech, I use equal lengths of welding wire (in this case 32") to visualize the tubing lengths and routing, and then build it from there.

What is an acceptable length tolerance (in percentage from the nominal length) to still consider all pipes an equal length, e.g. for a turbocharger setup? Dieter

Unless you are going for max power with a turbo...don't even bother! Go for shorter lengths for faster spool-up time. Equal length runners for a turbo (IMO) are great with large turbos, big cams, high rpms, but generally don't matter much on a low boost/small turbo street engine. Even for an N/A engine, if you are within 1-2", you are doing GREAT. Most headers are horribly unequal-length. In the case of this Sportwagon header, I got it within 1/2" of being dead-nuts equal. Good enough for me...

Remember my racing turbo header for my Manta? 8000 rpms and 500 hp capability made me decide to build it that way. But my 1971 Ascona wagon is getting a small GT25 turbo and I built the manifold with packaging and spool-up as my main concerns.

[Phoenix]

Good grief! Seeing something like that just leaves you speechless. It's a work of art.

[RallyBob]

While I'm at it, here's the old tranny mount, and the new one I built. The old one was a stock 4-speed mount that was hacked with a sawzall, and reversed front-to-rear (tilt was wrong!). Note the metal started to tear where it was sawzalled. The tranny was hanging very low on that side, pressing down on the old exhaust system, making it hang lower than usual.

I made it from 12 ga steel, and added some reinforcement ribs to it. It does not deflect at all, even with me hanging my fat 225 lb a$$ under my lift.