While I was allset to take my 400sbc and stroke it to a 420, my buddy has shown me some real impressive numbers with a destroked 377/380. He believes that I won't be able to put down the power with such high torque from the stroker down low & I'll be able to use it more if it builds as the rpms climb..... With the TKO and the 3.90 gears I can spin quite well in 1st & 2nd gear with the present 350 :) .

So which is it ? This is a weekend warrior and occasional autox/ strip car.


[Modified by SmokedTires, 6:00 PM 11/6/2002]

 

I have seen a 377 run at the local circle track. That thing screams. I would also agree that off the line, you would not be able to put huge torque without breaking stuff. The motors can be made to perform equal, just one you would want to run at say 2000rpm's and hammer it, the other you may have to run it to say 3500 rpms. Also, there was nothing like that 540 horse alcohol modified with the 377 turning 7500+ down the back straight. You can feel your skull rumble. There are 8 or 9 406's and twice that many 383's running at that track that I know of, and not one is that :cool: :cheers:

 

what are you using the car for ? is it a race car or a car you want to drive once a week ? is it a car you drive every day ? 383 on a daily driver here and i can tell you gas aint cheap. :cheers:

 

either do a 6" rod 406 or possibly try the 377, you always could use more cam & a short runner to kill bottom end torque and promote top end horsepower ya know :p:

 

For a car that will see the majority of it's time on the street, I'd say go for the stroker. It will provide you with much more area under the torque and power curves, and give you a much wider usable rpm range. The only time I can see the benefit of destroking an engine is when you are displacement limited due to rules requirements or weight breaks, or you are in need of higher rpm to take advantage of gearing required for increased top speed. I would not think autox wouldn't qualify since most of the autcross courses tend to be relatively low speed featuring plenty of corners requiring torque to get you off the corner or out of the hole.

I had a TKO in my car when I had the 650hp/580 tq (425 ft lbs at 2000 rpm, and 500+ from 3000 thru 7000rpm) NA SBC 427 and with similar gears to yours, I concur with the assessment that it can be overwhelming to the tires, but don't fall victim to the belief that a stroker can't be spun up if you need or want to. I had my 4.0" stroke up to 7500 several times on the dyno and on the street. With the 256/264 cam, is was past the curve but it was more than capable and willing to go up there.


[Modified by Monty, 12:45 PM 11/7/2002]

 

Not that Monty's stupid though! ;)

 

Ok since most votes so far are for the 406, here is what I have so far for a possibility.........

 

Yo my Tire Smoking Syracuse Buddy!

(6" rod 406, 383 or 377 ?) Let’s lay everything on the table.

Let's start off with the 406 6" rod Standard GM 400 9" deck Block"
The 406 should have the lighter BOB weight compared to the 377 since the wrist pin would be moved closer to the top of the piston. This light weight will help acceleration but could hurt reliability. Especially if the pin is up in the oil ring. The 3.75" stroke crank will increase piston speed / acceleration which in turn increases intake velocity and low-end torque but could limit higher RPM usage. Also the 3.75 stroke would also increase piston side load / friction. Block filler would be good insurance with a stock 400 block as well as billet main caps / ARP studs. Also consider that you would probably need a small base circle roller camshaft for this build $$$.

Now the 377 6" rod Standard GM 400 9" deck Block"
The 377 would have a slightly heavier BOB weight of the three since the wrist pin would be moved away from the top of the piston, but that’s not a bad thing. I don't think you would feel the difference in performance though, probably less than 150 grams. Reliability would be better with the 377 by 1. The greater strength of the piston at the wrist pin and the thicker top ring land. 2. Better rod to stroke ratio. 3. Reduced piston side loads, stress & friction. Block filler could be omitted as long as the block was strong and an ultrasonic cylinder wall thickness test was done. Either way I would still use the billet main caps / ARP studs. And last you could use a standard roller camshaft without the clearance worry.

The 383 6" rod Standard GM 350 9" deck Block"
The 383 would suffer with the smaller bore which limits air flow by shrouding the intake valve. Everything else would be similar to the 406 above.

Both the 406 and the 377 will have increased flow with a given cylinder head over the 383 since the larger bore un-shrouds the back side of intake valve at high lift.

With all this said you need to ask yourself what you want? The 406 in most cases will make more power and gobs of low-end torque. But do you need that much torque down low? If this was a solid axel bracket car with slicks I would go with the 406 but with an IRS Corvette, 3.90 gears and that :cool: 5 speed I'm in favor of the 377. You know what it feels like with you mild mannered 355 at the Glen. Just imagine what a 600HP fire breathing 377 would feel like on the straight away! Horse Power is all about Torque and RPM and where you need it!

Hey by the way I brought my little girl home today!!! I put a picture of my little garage helper on my web page. Check it out! :crazy:



[Modified by Stingraycrazy, 12:59 AM 11/23/2002]

 

If you want to see what the difference is between a 406 & 377 look for a copy of chevy high performance back in the summer I read where they tried this.
They built the same engine but changed the stroke ran it on the dyno then ran both engines in the same car at the drag strip. 406 wins both at the strip and the dyno. Things like side loading the cylinder is a little overblowin do you think that you will be able to hammer on it for 100,000 miles without a rebuild. Most of us will run a few years or less then build another engine. Monty is right the larger engine is much better for the street. You talk about first gear but what about third or four that is wher the torque will kick azz on the smaller engine :cheers:

 

I'm going to inject another angle into this debate. Normally, I would prefer a 377 long rod engine and a big hairy solid roller cam with a set of steep rear end gears. However, for the type of cam necessary to take advantage of the 377's high rev capabilities, I doubt you'd be able to pass an emissions test.

Therefore, in your case, since you have a later C3 that requires a smog test, I'd recommend the 406, but only if you use the 6 inch rods. That will give you very good torque, so it'll be an excellent street engine as well as an excellent choice for the strip also. A good weekend warrior engine.
You could probably go with around a 230 to 234 degree (@ 0.050) intake grind and still do adequately well with emissions. However, I question whether you even HAVE an emissions test with those sidepipes.
(Do you?)

If you don't have an emissions test, I'd be tempted to try a 377, with long rods, fuel injection, and a good centrifugal supercharger. That'd be a nice "Jeckle and Hyde" engine. Very streetable in stop and go, but a high revving monster when your foot's in it.
But for streetability, torque really is the best.