How much HP is a 38DGAS good for?

[neuropel]

So what is the upper limit where a 38DGAS is no longer sufficient? When doing all the various upgrades we talk about here (big valve heads, 2.0, exhaust, etc.), which points should one move from a 32/36 to a 38DGAS, and from a 38DGAS to Dual Carbs? I know there's overlap, but can someone chime in on some basic guidelines? For example, are the guys that have done the 1.9stroker to 2.4 totally limited to dual carbs for performance (not counting EFI)? How about the Holley 500 or a SSD?

Todd

[RallyBob]

So what is the upper limit where a 38DGAS is no longer sufficient?

They're pretty good up to about 140-150 hp, after that I end up boring the venturis out for more airflow, but this mod hurts low end power a bit. If I have to stick with a single carburetor the next step is a Holley 500. Gregg's (Samdog's) 2.5 litre made 152 whp with a single Holley 500 (about 178-182 hp at the flywheel), and that is still a pretty mild streetable engine by my standards, definitely not race-spec. My friend's old 2.1 circle track Opel made 192 hp with a Holley 500 2 bbl reworked to flow 630 cfm.

This is in reference to an Opel only, I've seen 160 hp on a built-up Toyota 22R with a 38 DGAS without much trouble. I'm sure there are other engines out there with more (as well as less) hp potential from the same sized carb.

Bob

[N61WP]

When I was running a 38 DGAS on my 2.0, I reached a point where I was draining the fuel bowl while racing. It would hit a brick wall in 3rd gear at about 5500-5800 RPM. With the mods I have the engine is guessamated at about 150 HP. I changed to a SSD 45 DCOE, using the same fuel pump, and haven't had the same problems.

Jc

[RallyBob]

When I was running a 38 DGAS on my 2.0, I reached a point where I was draining the fuel bowl while racing. It would hit a brick wall in 3rd gear at about 5500-5800 RPM. With the mods I have the engine is guessamated at about 150 HP. I changed to a SSD 45 DCOE, using the same fuel pump, and haven't had the same problems.

Jc

Yea, the DGAS/DGV has a much smaller fuel bowl than a DCOE. At about 135-140 hp at the flywheel you'll empty the fuel bowl at the top end of 3rd gear. A bigger fuel line (more volume, not pressure) is required at that point. The same thing will happen with a single DCOE or a Holley 500, but not until much later on because of the larger fuel bowls they have. Twin DCOE's naturally have twice the fuel reserves as a single DCOE.

[opelnut10]

Everyone has their own system that they think works best, and depending on engine displacement,compression,cam timing and fuel delivery they may all be right. The bigger the horse the more you have to feed him if you want him to plow Downdraft weber 32/36 or 38 is a very good carb. outta the box, can get better with tuning. Sidedraft weber is even more tuneable, more parts available such as venturi,chokes and venturi stacks along with the jets. Sidedraft works better on a Manta or Ascona because you can get out farther from the head (more low end torque) better suited for every day driving. Now we come to the Holley, I like it because I know a lot about tuning one. 350CFM small cc engine and 500CFM 2200 and over with big valves, good cam and good exhaust system. To use the Holley if you do not have the right manifold (Cannon) then you need port work done to the Opel manifold and adaptor and that requires someone with a flow-bench and the knowledge to properly improve the flow of the manifold.