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Old 02-18-2004, 11:57 AM
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355, 377, 383 or 406? That is the question!

The way I see it, and please correct me if I am wrong, is that a longer stroke is better for torque while a short stroke/larger bore is better for horsepower and is easier to reach higher RPMs with.

If this is true, why does popular opinion say that to make a 350 better it needs to be stroked but if you are going to run a 400 it should be destroked? While still others say more cubic inches is the main consideration.

I realize that not all people have the same opinion but the above generalities seem to be true.

The reason I ask is that I am preparing to build a strip only small block Chevy that needs to produce a minimum of 450 horsepower at the flywheel. Which of the above options would produce this goal considering both cost and reliability?

Many thanks!

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Old 02-18-2004, 01:13 PM
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Torque wins races enough said. And building a strip only 450Hp small block can be done easily. At the level it looks like your aiming for your making this harder than it has to be.
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Old 02-18-2004, 01:37 PM
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Having a short stroke means that your piston has to travel a shorter distance for each revolution. This being the case, per revolution, the piston speed will be slower in a short stroke engine rather than a longer stroke engine. This causes less friction, and there is just less overall stress on the parts. But unless you are going to be running 7500 and greater RPM, the benefits of a short stroke motor are negligable. A longer stroke will get you more hp becaue of more cubic inches and more torque because of the additional stroke. I have a 358 destroked 400 that gets rapped to 7800-8000 RPM and makes 600hp and 460 ft lbs with 14.7:1 compression. In this case, a short stroke has some benefits. But I know of a 406 for sale that makes 650 at 7000 RPM and 550 ft lbs with 10.5:1 compression. Both of these motors have aftermarket ported heads,mechanical roller cams, and are matched well. The only reason I would destroke a motor is if you are going to be running at very high RPM.

Adam
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Old 02-18-2004, 01:43 PM
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Bottom line, most bang for the buck: 406
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Old 02-18-2004, 01:47 PM
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Adam, made some very good points.

I agree with 383Monte as well, 450HP is not going to even be a challenge for a strip only car. You can make that with any of the engines you listed.

What you have to consider is: How heavy is the car? Auto or stick? Rear gear ratio,? Tire size (height)? 1.8th mile or 1/4 mile? Once you answer these questions one engine might be better for what you are trying to achieve.

No, a shorter stroke does not mean it makes more HP. While a longer stroke does "help" make torque, the difference is not always relevant.

If you want to build a 450HP engine that will last a long time and have low maintenance, then build the largest small block you can. Cubic inches make more torque and HP, it also allows you to do it at a lower RPM. This way there is less stress on the engine and components. If I were in your shoes and already had a 350 block I would go with a 383, if you already have a 400 block, by all means build that. Of course this will depend on what your answers to the questions above are.

Royce

Edit: Depends on who you listen to, the saying is Torque is king on the street, but HP wins races. Torque gets you moving and HP keeps you moving. It all depends on the application. You can't have HP without Torque and visa versa. You just have to decide where you want the torque and or HP.
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Old 02-18-2004, 01:51 PM
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Bigger bores have the potential to produce power, No matter how you look at it.

In short:

A 4" bore is about the minimum for large valve situation's. A 4.125 bore is better. A 3.48" stroke is a little short for best torque production. The 3.75 stroke is a little to long for 8000 plus. So either running a big bore/short stroke or a small bore and slightly longer stroke for low speed power corrects what the engineer's of GM should have done if price wasn't such a issue.
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Old 02-18-2004, 03:41 PM
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I am building car that I believe will weigh in about 3300 lbs with driver. I will probably be running a TH350 tranny with whatever torque converter is needed. Right now, I am looking at buying a 9" that has just been setup and the guy needs a little money. It has been narrowed with new axles and a spool but only has 4.56 gears.

My thoughts are as is mentioned above. Maximum cubic inches at lower RPMs will not have to run as hard to make my goal. This should help the reliability and longeveity issues.

Maybe I am wrong but this is what I am thinking.

One thing I forgot to mention is that I want the engine to run absolutely no power adders. This is also my first drag car built for strip only.

Guess I will probably go with a 383 because I have quite a bit of stuff sitting around for it. Only need the crank and maybe 6" rods.

Thanks, guys. I appreciate the help.
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Old 02-18-2004, 05:39 PM
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I would go for the 406 anyday. To me, if you can make the same power with a 6,000 rpm 406 and a 7,000 rpm 355, then the 355 is more likely to break bottom end parts due to rpm. Now, if you can afford all the best in bottom end parts, then this may not seem big. But if your on a budget, then it definately is.

Also, say you got a combo that is roughly worth 1.3 HP per cubic inch. In a 355 that is 461 HP. Same combo but in a 406-
527HP.
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Old 02-18-2004, 06:14 PM
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"only 4.56's" my goodness, that is plenty of gear. Depending on how tall the tire is, you may want a higher winding engine.

Royce

Edit: Firechicken, it doesn't wuite work out that easy. You are correct that "IF" you were to get 1.3 per cubic inch from each engine. You didn't mention the 383 that would come in at 498HP. For the price the 383 might be a better deal, if he has parts already.

Just something to think about.
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Old 02-18-2004, 06:37 PM
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Yeah, I don't have the block or crank for a 406. I will probably go with the 383 with 5.7 rods. I would like the 6" rods but then they would up the price, not to mention that the pistons seem more expensive for a 6" rod 383.

Anybody have a cam recommendation for a 450HP 383. I am leaning towards a roller cam but would consider a flat tappet.

Thanks again for all the help.
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Old 02-18-2004, 06:54 PM
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To make 450HP out of a 383 you really don't need a roller cam. A flat tappet hyd. would get you there. Since you are running somewhat steep gears I would go with a solid flat tappet cam (if I were in your shoes).

Pick the cam company of your choice, call them and tell them your goal. Asking for a cam recommendation on here or any other board usually ends up with 20 different people answering and suggesting 20 different cams.

I do know a guy running a 383 with trick flow heads, comp cams 292S (solid flat cam), with 3.55 gears he is in the mid 11's which with the weight of his car comes out to about 500HP. On pump gas.

My 385 with a hyd flat cam, Dart Pro 1 heads, in a 3500lb car ran 11.90 on street tires with 3.42 rear gears and a turbo 350 (3000 stall) This comes out to ~500HP as well with slicks it would have gone 11.60-11.70 no problem. On pump gas

With the added gear and compression you have and lighter car you should have no problem going low 11's/high 10's

Royce
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Old 02-18-2004, 08:46 PM
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It's very weird that you guys are running mid 11's with pump gas motors and I know guys with 14:1 race build 434's bairly in the 10's in roughly 3500 lb race cars. One guy dynoed his and it made like 560 and 600 torque?? If it's strip only I would definately build it for HP over torque
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Old 02-19-2004, 01:01 AM
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Nothing strange about running 11's on pump gas. Quite a few guys are doing it. It is a challenge and it is not always easy. It's all about a well thought out combination and getting the car to hook. I like being able to drive to the track and beat some of the cars that come off the trailers. It is not hard to go fast on race fuel, big compression big cam and gear accordingly. I just don't see how it can be fun to only be able to drive the car 1320ft at a time. It doesn't matter if you make 700HP if you can't get it to the ground the 450HP car that does is going to beat you.

Royce
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Old 02-19-2004, 08:23 AM
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The c.u. displacement is all about your application. Don't know that much about drag motors, but the most popular combo for the top dirt late model racers right now is a 388 c.u. for 1/4 to 3/8 mile tracks. This is done with a 4.125 bore and a stroke somewhere around 3.5. Most of these guys have a 406 or bigger for tracks larger than 3/8 mile. These motors usually have a SB2.2 or 18 degree top end. The reason the 377's and 388's work so well on a 1/4 and 3/8 mile track is because they don't spin the tires so much coming off the corners but have plenty of horsepower to get you down the strait away.
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Old 02-19-2004, 08:40 AM
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This seems to be a budget build for a 3300 car. So I would go 383 with a decent set of heads, WP Sportsman 200's. Good bang for the buck. Camshaft won't have to be to radical. A mild roller in the 230is range would do it or a hyd. flat in the 250ish range.

Chris
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