Sportwagon from hell...header pics

[oppositelock]

Very clever, Bob. Always coming up with new ideas. I can appreciate the amount of work that goes into building custom headers having just built a set for the Lexus IS-F's that we're building for the Speed World Challenge GT series (actually, two cars and probably a third later.) These cars will have 4.7 liter V8 engines. Here's some pictures of the headers I made. This is just a pattern set, really. We bought four boxes of used inconel headers from a Grand Am prototype team that was using the same engine, like 5 or 6 car sets, for $500! These headers would have cost about $6000 each set when they were new! Anyway, I used those for the flanges and collectors and bends and cut them up and welded them together into something that would fit our cars. The engine builder had very specific parameters for the header design. 1.75" primary for so many inches into 1.875" for so many inches into 2" for so many inches, certain cylinders paired together, crossover in a certain place, etc. Oh, and they have to be equal length and fit around the steering shaft and dry sump oil pump in a very tight engine compartment with the engine sitting right on the crossmember and set way back. Which is why they look like the bundle of snakes that they do. Very challenging, lots of trial and error fitting. It took me 2 weeks to build these (along with doing a few other things.) From these patterns jigs are being made so they can be copied several times over. Subsequent sets will look much nicer since there won't be as many seams and some of the bends can be made a little smoother.
Anyway, just thought I would share part of the reason why I haven't made any progress on my Ascona restoration lately. And maybe a little insight and acknowledgment to the amount of time and work that goes into these projects that Bob gets himself into.

[RallyBob]

Originally Posted by oppositelock Anyway, just thought I would share part of the reason why I haven't made any progress on my Ascona restoration lately. And maybe a little insight and acknowledgment to the amount of time and work that goes into these projects that Bob gets himself into.

Thanks Dave.

I see you've been busy! But you still gotta get that Ascona done!

BTW, Andrew bought Chris' Golf rally car, and is running it at Tennessee this weekend. Should be interesting!

Bob

[oppositelock]

Originally Posted by RallyBob Thanks Dave. I see you've been busy! But you still gotta get that Ascona done!

It'll get done, eventually. Motor is being worked on now. Pistons were just ordered.

BTW, Andrew bought Chris' Golf rally car, and is running it at Tennessee this weekend. Should be interesting! Bob

Yeah I know, Andrew was just out here last week for Oregon Trail rally where all he did was win 2wd MaxAttack! (for the second year in a row) and 7th overall in the National in a borrowed 1989 Honda Civic. He'll be a holy terror in Chris' car!

[RallyBob]

After some time off to do more work on my shop, such as new shelving and cleanup and my new welding bench, I finally finish welded the exhaust system two night's ago. And as of last night the header is almost completely welded too.

Wall shelving finished.
New welding bench.
Exhaust breaks down into 3 separate pieces.
Full exhaust view 1.
Full exhaust view 2.
Closeup at v-band connection.

[RallyBob]

While I was waiting for the front shocks to arrive, I also decided to set the new vehicle ride height. The old front springs were pulled and replaced with a set of 420 lb springs I had laying around. The car looked great with them installed, but admittedly they were a bit low for a daily driver. Plus there would have been a lot more work involved to cure the geometry changes for the lowered ride height.

I ended up wanting to raise the front ride height by 3/4". A bit of math with the vehicle's motion ratio (.6355) showed I needed to make the spring itself 'longer' by .476"...or roughly 1/2". BUT, since I was waiting on some racing Bilstein high pressure gas shocks, I also knew that the high pressure gas tends to raise the ride height as it's load bearing. So I chose instead a 3/8" thick spacer for the spring, which I made from UHMW plastic. Once the front springs were fitted, I then lowered the car on the ground and measured the rocker panel heights (8.5" front). I needed to drop the rear of the car by 1.25" to coincide with the new height I wanted, which was exactly 9", giving a 1/2" rake.

After cutting the rear springs to the correct height, I re-rated them on my spring tester, and they came out to 180 lbs, which is just about perfect for the handling balance I desired. Got lucky there!

I should add that the springs in the car previously were aftermarket (200 front/130 rear), and while I replaced the fronts I re-used the rears, albeit cut-down.

The front end geometry still needs to be altered, specifically the bump steer and alignment. Shock mounts have been lowered both in front and out back for increased compression travel. The rear geometry will also change, and in fact the new rear axle already has the trailing arm attachment points altered, and a fully adjustable panhard bar...both for length AND for roll center height (at both the body and the axle end). Change one thing and it changes a dozen others!

Lowered Sportwagon side view.
Sportwagon 3/4 front view.

[RallyBob]

Oh, and one last thing. California car or not, the driver's side jack pad is shot!
The passenger side is perfect, not even any surface rust. But this side is rotted away 80%, and the floor above the jack pad is already gone too...

Jack pad 1
Jack pad 2

[jordan]

Looks awesome, should be a real sleeper with that exhaust system! Looks like you still have some fun work ahead of you with the jack point...better you than me

[RallyBob]

Originally Posted by jordan Looks awesome, should be a real sleeper with that exhaust system! Looks like you still have some fun work ahead of you with the jack point...better you than me

Actually the jack points are easy to do...maybe 2 hours of work. It's more work to repair the floor correctly and keep the contours.

[RallyBob]

For the do-it-yourselfers out there, this is the breakdown of parts I used to make the exhaust system.

2.5" 'J' bend from T304 stainless steel (2 used)
2" 'J' bend from T304 stainless steel for over-axle pipe (1 used)
2.5" straight T304 stainless steel tubing (1 used)
1/2" stainless steel hanger rods
Preformed 2.5" stainless exhaust band clamps (2 used)
2.5" v-band exhaust clamp
Magnaflow 14" satin stainless muffler, 2.5" (front position, only fits 1975 California Opel floor pans!) offset/center
Magnaflow 14" satin stainless muffler, 2.5" (center position) center/center
Magnaflow 18" satin stainless muffler, 2.5" (rear position), offset/center

Of course, I welded via TIG, and used 1/16" thick 309 filler rod.

I also have some Powerflex urethane exhaust hangers on order. Rubber hangers just allow too much movement and the exhaust (tight fit!) hits the body and gas tank with them.

Of course, keep in mind I've modified other components to make it all work (like the torque tube crossmember, etc). But at least I know the exhaust will outlast the car now...

Bob

[RallyBob]

I've made some progress. Or at least tonight it feels like it!

I should have the header back from Jet-Hot very shortly, tomorrow or Friday most likely. My special-order urethane exhaust hangers never came to fruition, so I found another source and have to order those tomorrow as well.

The big feeling of success is that every part for the rear suspension/axle/brakes has had the final mods done prior to powdercoating. Everything has been installed, tweaked, removed, welded, re-installed, cycled through full suspension travel to check for clearance, etc....probably 10 times over. But I'm very happy with the results, and tomorrow I get to drop everything off for powdercoating. Then I begin the process of the front suspension re-engineering, and finally removal of the suspension and the engine/tranny assembly prior to painting under hood.

I have to stop by my friend Al's one of these nights and download the latest photos to his computer for some updates, I still can't load photos on my own computer.

Bob

[BQS4]

Bob;
The hangers you mentioned, are they the round ring OEM type, but, in urethane?

[RallyBob]

Originally Posted by BQS4 Bob; The hangers you mentioned, are they the round ring OEM type, but, in urethane?

Nope. I friggin' hate the OEM Opel hangers. What a crappy design! They break all the time, and even when they're new, they are bouncy and let the exhaust rattle and hit parts of the floorpan.

Newer cars all pretty much use a hanger that is essentially a rubber biscuit with two holes for the hanger rods to fit through. They're a big improvement over the Opel ones, but the aftermarket urethane ones are WAYYY stronger than even the modern rubber ones and do not bounce at all. And knowing how I like to modify suspensions....rubber is just too soft. It doesn't help that the exhaust is so much bigger than stock that the proximity to other components is very close. So I needed to mimimize exhaust movement as much as possible.

These are the hangers I'm ordering, but I'm getting mine with a 12 mm hole ID rather than 15 mm. The metal hanger rods I have are 1/2", so that's roughly a .028" interference fit.

[Bill Hoffmann]

I'm thinking about upgrading the exhaust in my '75 2.0E Manta. I had a nice mandrel bent 2" system but it rusted out (after almost 20 years - I can't complain). I plan to cut the head pipe at the 'Y' and go to 2" diameter. Bob's recommendation is to use at least a 2.25" over-the-axle pipe. Two questions:

1. Where is the best place to make the transition? I would think before the muffler, since there's more clearance there. The muffler outlet is crowded enough as it is, needing to bend immediately up. My concern is whether that will have an adverse effect on the muffler's designed function (high flow with sound reduction).

2. Should the rear muffler be 2.25" diameter also, or would it be better to reduce it back to 2"? The same concerns apply.

O.K., one more question: Any recommendations as to baffled or straight-through mufflers? I imagine the rear will be straight-through, but will it be too noisy with both that way? I have a straight-through Dynomax on my autocross Manta, and with just a pipe out the back, it's just too loud for a street driven car.

All opinions are welcome.

[Paul]

Originally Posted by Bill Hoffmann I'm thinking about upgrading the exhaust in my '75 2.0E Manta. I had a nice mandrel bent 2" system but it rusted out (after almost 20 years - I can't complain). I plan to cut the head pipe at the 'Y' and go to 2" diameter. Bob's recommendation is to use at least a 2.25" over-the-axle pipe. Two questions: 1. Where is the best place to make the transition? I would think before the muffler, since there's more clearance there. The muffler outlet is crowded enough as it is, needing to bend immediately up. My concern is whether that will have an adverse effect on the muffler's designed function (high flow with sound reduction). 2. Should the rear muffler be 2.25" diameter also, or would it be better to reduce it back to 2"? The same concerns apply. O.K., one more question: Any recommendations as to baffled or straight-through mufflers? I imagine the rear will be straight-through, but will it be too noisy with both that way? I have a straight-through Dynomax on my autocross Manta, and with just a pipe out the back, it's just too loud for a street driven car. All opinions are welcome.

Bill
On my 75 Manta with +.030 flat tops, Roger Wilson big valve head and CamTech cam, I'm running a DynoMax Super Turbo muffler with a Hooker dual resonator tip. The sound is pretty close to the compromise I had hoped for. I think the back pressure loss is less than a regular muffler, but may be a little more than a straight thru type.

The sound at idle is deep and throaty but not too loud. When you pull redline++ in 1st and 2nd, everyone can hear it. Cruising down the highway at 60+ you really don't even hear it, so you don't have to turn the radio up. When you are cruisn' its hardly noticeable, but when you get on it you can hear it nicely. Sounds great going under the overpasses. It sounds so good, I find myself driving around without even turning on the stereo just to hear the exhaust note!!!

The only one thing I'm not over joyed with is the drone in the cabin between 2200 and 2500 rpms. But you're gonna get that with anything other than the stock set-up. I really don't even notice it unless there is someone else in the car....

I chose the 2-1/4" muffler since the 2" pipe from the header slips just inside of the inlet to the muffler. Exiting the muffler we used 2-1/4 mandrel bent tubing over the axle and into the inlet of the dual tips. Looking back, if I had to do it again, I might try using just a 2" muffler and 2" mandrel bent tubing. I know RallyBob has always said to use 2-1/2" for the over the axle due the necking down of the pipe from the bending process. So I kinda tried to split the middle. But, after lowering my car, I found there was not much room for the 2-1/4" pipe so we have a few rattles on hard bumps. And who knows for sure, but the larger 2-1/4" vs 2" mandrel bent stuff may have cost me a couple of lb-ft of torque down low. However, when I run it up to 7,000 RPM I sure like the bigger stuff....

Here some links to follow...

Dynomax :: Mufflers :: Super Turbo

Hooker Headers 21417HKR - Hooker Exhaust Tips - summitracing.com


You can see pictures in the thread called Finally It Lives, in the Manta forum

For my daughter's GT with a stock, Low comp engine, I used the Walker Thrush Turbo muffler since it was cheaper. It still has a very good sound. Relatively quiet at idle and gets progressively louder as it revs up. In her car there is no interior drone. Still it sounds great driving with the windows down or reving the engine at idle. I used 2 single resonator tips for the classic look.

I cut her head pipe at just the right spot where a 2" pipe blended in nicely. Also, I took extra time to do a little clean up in the interior where the two down pipes merge as there is a big hunk of tube sticking out causing lots of flow restriction....

Sorry for the long and somewhat off topic post in the middle of Bob's great thread....

[Bill Hoffmann]

Originally Posted by Paul Looking back, if I had to do it again, I might try using just a 2" muffler and 2" mandrel bent tubing.

I am also considering staying with 2" just for clearance, but as you said it depends on if I can find a shop that can do mandrel bends. I like the muffler Bob used with the center in/out configuration. I'm wondering how close to the original sound I can get if my system is the same layout as stock except a bit bigger.

[Paul]

Originally Posted by Bill Hoffmann I am also considering staying with 2" just for clearance, but as you said it depends on if I can find a shop that can do mandrel bends. I like the muffler Bob used with the center in/out configuration. I'm wondering how close to the original sound I can get if my system is the same layout as stock except a bit bigger.

Bill

The mandrel bends were purchased. The muffler shop just cut and installed them in the proper configuration.

The more modifications you've done to the engine, the more muffling will be required to keep it quiet. I'd be willing to bet that even @ straight thru mufflers like will still be much louder than stock. That's why I'd had to use the offset in/out configuration...

[RallyBob]

Originally Posted by Bill Hoffmann 1. Where is the best place to make the transition? I would think before the muffler, since there's more clearance there. The muffler outlet is crowded enough as it is, needing to bend immediately up. My concern is whether that will have an adverse effect on the muffler's designed function (high flow with sound reduction).

I make the transition from 2" to 2.5" directly after the front muffler. In fact, you can almost chop the outlet from the muffler off completely, and simply weld the larger 2.5" pipe to the muffler body here. Short and sweet...
However the transition back from 2.5" to the rear 2" muffler is a bit tougher to do. I make a small tapered cone usually to merge it.

2. Should the rear muffler be 2.25" diameter also, or would it be better to reduce it back to 2"? The same concerns apply.

I've tried both ways. I did a full 2" exhaust with 2" mufflers (one before, one after the axle), and a 2.5" over-axle pipe. I also did 2" exhaust with 2.5" mufflers and 2.5" over axle pipe. The full 2.5" muffler setup was slightly louder, and deeper toned. A bit less bottom end power, more up top.

O.K., one more question: Any recommendations as to baffled or straight-through mufflers? I imagine the rear will be straight-through, but will it be too noisy with both that way?

Straight through for me only. But you have to use the largest mufflers you can fit for more sound suppression.

Originally Posted by Paul And who knows for sure, but the larger 2-1/4" vs 2" mandrel bent stuff may have cost me a couple of lb-ft of torque down low. However, when I run it up to 7,000 RPM I sure like the bigger stuff....

I've actually found the larger over-axle tube (2.5") improved low-end torque compared to the 2", even on a near-stock engine.

Sorry for the long and somewhat off topic post in the middle of Bob's great thread....

Nonsense. At least you guys are talking about exhaust systems. I strayed more off the subject myself talking about suspension and brake upgrades!

Originally Posted by Paul The more modifications you've done to the engine, the more muffling will be required to keep it quiet.

Absolutely. Compression and camshaft alter the sound the most, but any engine that makes more power will be louder for a given exhaust system. Hence the three mufflers on Gregg's wagon....roller cam 2.5's are not necessarily quiet.

Bob

[RallyBob]

Another interesting find on this Sportwagon. Both shock towers had spider cracks eminating from a single point. I checked all the other Opels I had laying around, and lo and behold it appears to be specific to Model 54's (Ascona wagons), as the model 51, model 53, and model 57's I checked were all okay in this regard. Right where the sheet-metal 'shelf' that is the rear floor pan is welded to the shock towers, there are stress cracks eminating from the spot-welds themselves. On one side the cracks were almost 3 inches long!

I attribute this to two distinct facts. The wagons have no rear firewall to support the rear shock towers, therefore there is considerable more flex going on here, and the only 'bracing point' is so far down on the tower that the flexing and leveraging happening here is trying to pop the spot welds. Secondly, this car was driven hard. The previous owner used to do track days with it in southern California. The current owner drives it hard, and it has stiffer shocks and springs which compound the loading on the chassis.

I've already welded the cracks up, but I think I will design a bolt-in rear brace for use in spirited driving and track days, but removeable for when you need the utilitarian aspects of the wagon most of all.

I'll post pics one of these days of this issue, before and after.

Bob

[oldopelguy]

A roll cage would give plenty of support for those pesky cracking areas. And while you're building one sportwagon cage, a second one would be so easy....

[Gary Sullivan]

I am also looking to redo/replace jack pads. Are you going to build your own jack pads (a while back seemed there was someone selling a few of those bits) ?

[RallyBob]

Originally Posted by oldopelguy A roll cage would give plenty of support for those pesky cracking areas. And while you're building one sportwagon cage, a second one would be so easy....

Maybe next year, but even still if he wants to retain some use of the wagon's original intent, I'll have to get creative around the shock towers.

I can only build them one car at a time, sorry! I don't have CNC tube bending equipment.

[RallyBob]

Originally Posted by Gary Sullivan I am also looking to redo/replace jack pads. Are you going to build your own jack pads (a while back seemed there was someone selling a few of those bits) ?

Charles Goin (Goin Manta) used to sell them. I think the exchange rate just made them unaffordable, so he stopped selling those parts.

I only have to rebuild the driver's side, the passenger jack point/floor is perfect. I'll make it from scratch, as usual! 12 gauge steel most likely.

Bob

[2 Fast 4 U]

Originally Posted by RallyBob 12 gauge steel Bob

Is that about 1 mm thick??

[baz]

this should help erik
AWG to square mm Wire Gauge Conversion

danged americans sticking to old units

[jeff denton]

About .105" according to my chart.