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Opeler
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I would like some help with a design for a torque producing head pipe for a 2.4L exhaust manifold. It's going in my GT, along with a 1.9/2.4L engine with 2-44mm Screaming Eagle CV carbs. Can anyone do a drawing with approximate dimensions, pipe dimensions, collector length and location.

Thanks,
Wes
 

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I would like some help with a design for a torque producing head pipe for a 2.4L exhaust manifold. It's going in my GT, along with a 1.9/2.4L engine with 2-44mm Sreamin Eagle CV carbs. Can anyone do a drawing with approximate dimensions, pipe dimensions, collector length and location.

Thanks,
Wes
Camshaft?
Head mods?
Compression ratio?

Too vague a request, but generally you'll need either 2.25" to 2.5" main tube diameter. A 2" headpipe is too small for a 2.4, while 3" is too big unless you have a really big cam and lots of compression and headwork. I'd use the 2.25" headpipe if you're using a mildly modded 1.9 head and modest cam and less than 9.5:1 compression.

I'd use 1.875" collector tubes off the manifold. The length of the tubes depends on where you are making the power. Longer for more torque and/or small camshaft. Shorter for more high rpm power and a bigger cam.

Collector length isn't that critical when you're talking about a 4-2-1 exhaust design. Just make a smooth merge. Bottom right of this page shows a 2-1 collector. Price for a mile steel twin/1.875" > into > 2.25" or 2.5" tube should be about $25, per this page.
 

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Opeler
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Discussion Starter · #3 ·
I don't know all of the specs. This is Calvin's engine, with a too hot cam, and roller rockers. The head was built by you, Bob. I has Legere Opel Engineering stamped on the side. I need to calm the thing down, with a more streetable cam. I am looking for a torque monster, and not a high rpm track car.
 

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I don't know all of the specs. This is Calvin's engine, with a too hot cam, and roller rockers. The head was built by you, Bob. I has Legere Opel Engineering stamped on the side. I need to calm the thing down, with a more streetable cam. I am looking for a torque monster, and not a high rpm track car.
I didn't do the head for him. Just recommended some valvetrain parts, that's all.

If the cam is designed right (even a big one), it will produce more torque than you know what to do with.

MantAscona's 2512 cc street Manta has a .504" lift/257 @ .050" degree cam (about 60 degrees more than stock), and idles at 900 rpms plus it pulls right off idle like a truck. It's all about the design intent, and the setup. The distributor recurving has a ton to do with the smoothness and driveability of the engine.
 
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...If the cam is designed right (even a big one), it will produce more torque than you know what to do with.

MantAscona's 2512 cc street Manta has a .504" lift/257 @ .050" degree cam.. It's all about the design intent, and the setup.
Wow, how so true!
It's all about the combination of parts all working together in complete harmony.
 

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Opeler
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Discussion Starter · #6 ·
Well there is no such thing as harmony here in Texas. I haven't been able to find a single person in Houston that knows anything about Opels. I've had a few hacks work on my GT, but it's usually one step forward, and two steps back. I have learned a ton from this forum, but there are things that I can't do. The Texas Opelers are so spread out, that it is difficult to even agree on a meet location. Anyone know of a traveling tuner?

This is all I know about the new engine;
1.9/2.4, bored and stroked. The head, is Bob's recipe, but also has the second generation (purple) roller rockers. The cam has 430 lift and 270 adv. duration @0.50 with 108 degrees of separation. Maybe not the ideal street cam. Compression was quoted @ 10.5:1. It also came with twin 48 dcoe carbs, and Cannon intakes that had been welded and runners enlarged to match the carbs. A fat 4-2-1 header was with it too. I have a 2.4L exhaust manifold. Getrag tranny. I am rebuilding the rear end with 3.89 gears, and have an NOS LSD unit. Currently, the exhaust is 2" to the muffler, and 2.5" over the hump and splits. Fuel line is 3/8" and has elec. fuel pump.

The engine is still on the stand, and I am working out the carb intake design for the CV carbs.

What I am asking for is an idea for the length and diameter of the headpipe tubes, and how far back on the car before they merge. This is a city car, so torque is key, and not so much about top end.
 

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Hey Wes, I got quite the experience with the big cam and making it run good on the street. OGTS told me that I would never get the OR-77 cam running right on the street but I did. I didn't have to rev it to the moon to get away from a light and it had plenty of pull from a stop. As far as the headers go I bought the new design one from OGTS. It's made by hedman and with 2-1/4 pipe connected to it it still had plenty of torque. I could tell a huge difference from the 2-1/2 setup I pieced together in the garage just to drive it from the house to the pipe bender.

If the cam in the engine has the specs Bob was speaking of then it can be done. Need lots of initial timing and for pump gas sake have to limit the total advance way down. I could see about getting out there and offering some help sometime. Let me know.

Too bad I sold the GT alittle over a week ago. You should have seen it. Amazing doesn't cover it.
 

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Opeler
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Discussion Starter · #8 ·
Thanks Larry,

I would like to have you help with the setup, once the engine is installed, and the carbs mounted. It may be a little while. It would be nice if it got a little cooler. Maybe in October.
Would you mind sending me your phone number in my PM? Congrats on selling your GT. I hope you got close to your asking price.

Wes
 

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Wes, I sent you my number.

I did ok. These cars just aren't selling all that well right now. Just the times we are in. I still have a few things available for sale from it. I have those Shelby Cal 500 wheels still. I need to get rid of those for sure also alot of glass too. Full set of gauges. If you or anyone else is interested let me know. I will be posting them soon.
 

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Humm [email protected] 108 LSA
I think your right about not being the ideal street cam.
It might work better on a wider separation say 110-112.
The only draw back is that the cylinder pressure will increase and you'll need
to watch the total timing even closer!
 

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Agreed, 270 @ .050" is huge. If you ran something in the upper 240's to low 250's it would run like a pussycat...purrrrrrrrrr.:veryhappy. And you'd have huge torque.
 

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IMO you only need to worry about LSA, anything over 110 should run decent. Get much under that then you get crappy idle, low vacuum, and a narrow powerband. That being said I really had no issues with the OR-77 Isky cam. Sure the idle was choppy and hard to tune but anything over 2400rpm and it was a serious rocket. I still didn't have any problems with the taking off from a stop and the idle quality didn't bother me. Another thing to consider is this is a light car so alot of low end isn't needed and if you are going to install different gears or smaller than stock diameter tires this makes the need for a wider power band less important. If you are changing the gears numerically higher and go shorter than stock tires then you really don't need alot of low end to get things going. It's going to reach the powerband quickly and therefore you won't notice any lack in torque. HTH.
 

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Opeler
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Opel GT Source Header

Hey Wes, I got quite the experience with the big cam and making it run good on the street. OGTS told me that I would never get the OR-77 cam running right on the street but I did. I didn't have to rev it to the moon to get away from a light and it had plenty of pull from a stop. As far as the headers go I bought the new design one from OGTS. It's made by hedman and with 2-1/4 pipe connected to it it still had plenty of torque. I could tell a huge difference from the 2-1/2 setup I pieced together in the garage just to drive it from the house to the pipe bender.
Was the OGTS header a simple installation? Header would eliminate the issues with the stock, Opel header pipe.
 

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GT Owner
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Well there is no such thing as harmony here in Texas. I haven't been able to find a single person in Houston that knows anything about Opels. I've had a few hacks work on my GT, but it's usually one step forward, and two steps back. I have learned a ton from this forum, but there are things that I can't do. The Texas Opelers are so spread out, that it is difficult to even agree on a meet location. Anyone know of a traveling tuner?

This is all I know about the new engine;
1.9/2.4, bored and stroked. The head, is Bob's recipe, but also has the second generation (purple) roller rockers. The cam has 430 lift and 270 adv. duration @0.50 with 108 degrees of separation. Maybe not the ideal street cam. Compression was quoted @ 10.5:1. It also came with twin 48 dcoe carbs, and Cannon intakes that had been welded and runners enlarged to match the carbs. A fat 4-2-1 header was with it too. I have a 2.4L exhaust manifold. Getrag tranny. I am rebuilding the rear end with 3.89 gears, and have an NOS LSD unit. Currently, the exhaust is 2" to the muffler, and 2.5" over the hump and splits. Fuel line is 3/8" and has elec. fuel pump.

The engine is still on the stand, and I am working out the carb intake design for the CV carbs.

What I am asking for is an idea for the length and diameter of the headpipe tubes, and how far back on the car before they merge. This is a city car, so torque is key, and not so much about top end.
Is this the spare engine sitting in your garage ?
 

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Opeler
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Discussion Starter · #16 ·
No, that motor didn't survive my machinist. I had him tear it down, and measure / fix areas of concern or wear. The consensus was that the motor had been run so hard, that the crank, which was stroked, was beyond useful spec, and the cylinders were egg shaped from the longer stroke revolutions. The only things that weren't trashed were the Weber 48's, and the Roger's Engineering head, which are both here on a shelf.
 
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