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The Young One
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Discussion Starter · #1 ·
Hi guys So I am curious to see how much horsepower a big valve head, and a Weber 40 DCOE would make. I have headers and a 2.25 inch head pipe with a glass pack and a 2 inch over the axle with a custom made glass pack resonator. My car is also a 1969 so it has high compression.

Thanks Sam
 

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There’s no easy answer to that.

It’s like asking ‘how much could a person bench press if they started going to the gym?’ There are so many variables.



So, that said, these are SOME of the variables that would affect the power increase from a big valve head and a single sidedraft 40 DCOE.

*What size venturis in the Weber?
*What brand/design of single sidedraft intake manifold?
*What length air horns will you use?
*Will you have a cold air box?
*Will you be using a stock camshaft?
*If you are not using a stock camshaft, what specific one will you use?
*What size valves in your cylinder head?
*Will the head be ported?
*If it will be ported, to what extent?
*Will the head be milled to increase compression?
*Will be engine be professionally tuned on a dyno afterwards? I’ve see racing Opel engines gain up to 17 hp by proper (professional) tuning.

You can see that just by varying any of these items you can have a huge range of expectations.
 

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The Young One
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Discussion Starter · #3 ·
There’s no easy answer to that.

It’s like asking ‘how much could a person bench press if they started going to the gym?’ There are so many variables.



So, that said, these are SOME of the variables that would affect the power increase from a big valve head and a single sidedraft 40 DCOE.

*What size venturis in the Weber?
*What brand/design of single sidedraft intake manifold?
*What length air horns will you use?
*Will you have a cold air box?
*Will you be using a stock camshaft?
*If you are not using a stock camshaft, what specific one will you use?
*What size valves in your cylinder head?
*Will the head be ported?
*If it will be ported, to what extent?
*Will the head be milled to increase compression?

You can see that just by varying any of these items you can have a huge range of expectations.
I would be using the stock cam. I won’t port the or mill the head. Do you have like a rough number like around 120hp or would it be less than that.
 

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Can Opeler
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Hi guys So I am curious to see how much horsepower a big valve head, and a Weber 40 DCOE would make. I have headers and a 2.25 inch head pipe with a glass pack and a 2 inch over the axle with a custom made glass pack resonator. My car is also a 1969 so it has high compression.

Thanks Sam
A properly tuned Weber DCOE and a stock 2.0L head, and long tube header boosted my power by 27HP with a stock cam. My block is also a 2.0L so 22-25HP would be more reasonable if you stayed 1.9L.

A properly tuned Weber DCOE on a bone stock high compression 1.9L with headers will increase power 20HP over the stock solex and a little less than that over a properly tuned and ported 32/36. About 10HP over a 38 DGAS with a tented intake.

This is based on my own measurements on my two cars combined with one dyno day of my own, and dyno charts from historical steinmetz ads.

And as Rally Bob said this depends on lots of factors.
I use the midikit intake. I recommend it above the steinmetz angle one.

Keep in mind I’ve spent literally thousands of dollars getting the DCOE to run perfectly on my car. I have a good tune for a stock 1.9L that will save you a lot of that cost though. But you don’t install a DCOE for less than 1k and enjoy it. Keep that in mind.
 

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The Young One
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Discussion Starter · #5 ·
A properly tuned Weber DCOE and a stock 2.0L head, and long tube header boosted my power by 27HP with a stock cam. My block is also a 2.0L so 22-25HP would be more reasonable if you stayed 1.9L.

A properly tuned Weber DCOE on a bone stock high compression 1.9L with headers will increase power 20HP over the stock solex and a little less than that over a properly tuned and ported 32/36. About 10HP over a 38 DGAS with a tented intake.

This is based on my own measurements on my two cars combined with one dyno day of my own, and dyno charts from historical steinmetz ads.
So is a Weber 40 dcoe the way to go and is it better than a Weber 32/36?
 

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Can Opeler
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So is a Weber 40 dcoe the way to go and is it better than a Weber 32/36?
Oh it’s way better in almost every way… if you don’t mind working on the carburetor and tuning several times a year, if you don’t care about cutting your mpg in half, and if you have over $1000 to throw at it.
The throttle response and power curve from a DCOE is something all opelers should experience. It’s light years better than a 32/26. But far far more finicky, harder to tune, and less reliable.

You don’t want one yet at your age. Wait until you have a few more years of working on these under your belt.

Also if I can give some advice that I’ve learned.
Don’t chase power unless you plan to race. All of the power mods you do will make your car feel fast for a few days until you get used to them and then it feels the same again. Focus on how you want the car to feel instead. How it handles, throttle response, noise, etc. that stuff doesn’t fade as you get used to it.
 

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I would be using the stock cam. I won’t port the or mill the head. Do you have like a rough number like around 120hp or would it be less than that.
Your stock 1969 engine was rated at 102 SAE Gross HP by GM. SAE Gross HP was used until 1971, and is partly responsible for the overinflated/overhyped 1960’s muscle car HP ratings. I’m not saying none of those muscle cars made their stated power, but most did not.

Anyway, the exact same 102 SAE Gross HP engine specification in Europe was rated at 90 PS (metric horsepower, or pferdestärke). Modern engines are rated in SAE net HP, which is roughly 98.6% of PS. So by today’s standards, your GT would be rated at 88.74 SAE net HP. I have personally had stock high compression engines dyno’d and they usually make around 82-85 HP.

Now, this is assuming perfect engine tuning, and perfect engine condition. Your engine is 52 years old, so it is neither! You would be LUCKY to have 70 HP.

If you bolted on a header and 2.25” exhaust to a 70 hp poor running engine, you’d be fortunate for see another 5 hp.

If you bolted on a fresh 1.9 cylinder head, unported, with factory 2.0 liter valves, and a single sidedraft 40 DCOE with 33 mm venturies and a Steinmetz ‘Midikit’ single sidedraft intake manifold, then you’d probably be making about an honest 95 hp.
 

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Which at this stage of your game probably not worth the effort and money right now and you maybe better focusing your attention elsewhere
Just my opinion, But a very good question to further educate yourself
 

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The Weber/Solex 40 dual side draft kits back in the day were rated at 105hp DIN and the Rekord Sprint engine with dual 40DFO down drafts was rated at 106hp DIN, so I wouldn't expect an increase of more than 5-6hp with a single side draft carb due to the less optimal single side draft manifold. So Rally Bobs estimate is very close.
 

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Opeler
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There’s no easy answer to that.

It’s like asking ‘how much could a person bench press if they started going to the gym?’ There are so many variables.
Sorry, can't resist but my answer would be 420 lbs................and 22 years ago.............:cool:
 

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Sorry, can't resist but my answer would be 420 lbs................and 22 years ago.............:cool:
Lol, yea but that doesn’t get to my point.

I just meant that people are sized differently, have different natural strengths, have different genetic propensities, have different work ethics and intensity, and not to mention I didn’t even give a time line! I didn’t say how long they had to get to that point when they might test themselves.

But for the record, when I was 33 years old and my sister was dying from cancer, I threw myself into fitness for about 3 months as a way to deal with the inevitable. I never went for a single rep max, nor did I ever use a spotter, but I did put up 260 lbs for 3 reps just to see what I could do. But yea…that was also 22 years ago!
 

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Pedal Smasher
1973 Opel GT
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Without rebuilding the engine, I don't really see the point in focusing on power adders for a 50 year old engine. It's a bit like waxing the body prior to sending it to a chassis dipper to remove the paint. At some point, you'll end up rebuilding the engine. Afterwards, you'd have to retune the carb because the engine is running better. If you want to restore a GT, wise advice I keep finding is to do all the mechanical improvements first. Then worry about all the pretty stuff. So, I'd say focus on rebuilding the engine first. Once you're ready for the cylinder head, then add the go fast bits. If you aren't ready for this, then just focus on improving the handling and ride quality. Chances are your GT needs new parts in this area too.
 

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Can Opeler
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Without rebuilding the engine, I don't really see the point in focusing on power adders for a 50 year old engine. It's a bit like waxing the body prior to sending it to a chassis dipper to remove the paint. At some point, you'll end up rebuilding the engine. Afterwards, you'd have to retune the carb because the engine is running better. If you want to restore a GT, wise advice I keep finding is to do all the mechanical improvements first. Then worry about all the pretty stuff. So, I'd say focus on rebuilding the engine first. Once you're ready for the cylinder head, then add the go fast bits. If you aren't ready for this, then just focus on improving the handling and ride quality. Chances are your GT needs new parts in this area too.
I get your point but I disagree with CIH. If it’s got good oil pressure and doesn’t smoke too badly go ahead play with it if you want. These things are tanks and will run well past their prime.

The power adders will still be good if you blow the engine. You’ll have to retune after a rebuild anyway. I’d rather test my power adders on an older engine anyway.
Besides I have an upgraded exhaust, DCOE, pertronix III, and such on my bone stock 1970 block, 1969 head, 12 bolt timing cover, Frankenstein non-rebuilt engine in my 72 GT and it will smoke my nice fancy 2.0L from 0-30mph. I tuned that baby for torque and it’s totally worth it. That engine won’t be getting rebuilt, but it may get supercharged soonish:)
 
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Detritus Maximus
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If your motor is tired and down to 70 up as Bob suggested, a rebuild, even a stock rebuild will feel stronger and get back 10-15hp. If you do a rebuild, do the big valve head if you want. Or it could wait to later.
I can tell you this, the rebuilt 2.0 I got from Gil (OGTS) felt quite a bit stronger than my old hi comp 69 (which was probably tired) and way better than my low comp 74 motor (also probably down on up after 225k miles).
It wasn't so much the 'extra' up as much as just getting back what should be there. All that was with an amateur (me) trying to tune the 32/36.
Later, when I put on the 38 DGAS was when it really seemed to change. The character of the car was totally different. Much more torque in the lower rpm made the car easier and more fun to drive. Probably didn't gain much hp, but it felt like it had.
 

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Ok, dumb question time, The Holley sniper unit that a few have used, and a few are trying out. Would that, (Sniper), be better than a set of 40 DCOE Carbs? Granted it wouldn't look as cool as twin 40s, or sound as cool, but you wouldn't have to fool with Jets, Etc, as it (Sniper), is supposed "to learn how you drive" or am I reading too much into what has been posted.
 

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Can Opeler
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Ok, dumb question time, The Holley sniper unit that a few have used, and a few are trying out. Would that, (Sniper), be better than a set of 40 DCOE Carbs? Granted it wouldn't look as cool as twin 40s, or sound as cool, but you wouldn't have to fool with Jets, Etc, as it (Sniper), is supposed "to learn how you drive" or am I reading too much into what has been posted.
I don’t think anyone has tried side by side, but I would expect it would out perform an average tuned single DCOE just by the fact it will be tuned near perfectly. It wouldn’t out perform an average set of duals or a good tune on a single.

The problem is the stock intake has terrible flow. I bet a sniper with a Rally Bob tented and welded intake would give my single DCOE one heck of a run.
 

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Mike Plinkerton, has experimented with a Sniper unit. I'm hoping to hear from him as well. I knew you were running a single 40 DCOE Kyler on your race Gt and your feedback is valued as the "voice of experience". I have a set of 40 DCOES that I picked up years ago, for my Manta, that went no where. So I've contemplated running them on the Gt. Just an idle thought.
 

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Opeler
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If money isn't an issue...has anyone looked at using an EFI solution in place of a 40 or 45 DCOE?


I had pretty good luck back in the late 80s/early 90s with a 38 DGAS on a mildly built 1.9L in a wagon. I redid the head, had it ported, and added the carb, long tube hedder, and 2.25 inch exhaust and it was a lot stronger. However, over time and with the foot of a teenager it started burning oil so I rebuilt the shortblock and upped the compression ratio (it was in a 71 kadett wagon so stock had low compression) and put in a mild cam. wow did it wake up with the bottom end built and 2 points more compression ratio. I also had the auto trans built and it would chirp the tires on the 1-2 shift and just roast the right tire when pulling away from a stop sign. LOL they were 155SR13 michelins and it was the 80s so my expectations were low.
 
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Pedal Smasher
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Gordon is currently working on a 2.4 that will use an EFI ITB. He considered the Jenvey EFI DCOE’s but he didn’t need it to look like a carb, so a less expensive option was chosen.
 
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