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Desktop Dyno Guys... Where can I get.... *UPDATE* How should I build my 383?

"Fast Burn" is a GM term, maybe its copyrighted, maybe AFR doesnt feel the need make up silly names for theur product. They do have the swirl-inducing heart-shaped chamber that GM did, apparently, come up with. I think recent testing has shown AFRs are the best choice out there. They also come in different chamber sizes.

I'm just not sure how much more power fancy alum heads will make in a mild truck motor. I'm am sure it'll help, if you got the xtra $, go for it, if theres budget concerns, I'm not so sure the xtra $ is worth it.

Vortecs may flow well, but they weren't designed for a 383. As supplied, the fast burns have better components as well.The fast burns absolutely trounce the Vortecs in both exhaust and intake flow numbers.
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BTW, GM uses Vortec heads on their own GMPP motors, theyre plenty big enough for a mild 383... What difference does all the flow #s make when youre cam choice limits you to 350 hp? And the "better" parts for your .4xx lift cam?
 
Some say that AFR came up with the desig for the "Fastburn/Vortec" chamber design. Eh whatever. They will work great for a mild 383. If I could afford them I'd gow tih AFRs, but thats me. I think as far as mild heads go(namely not high revving large duration motors) AFRs are the best.

Yes to say it again, AFRs use the "Fastburn" chambers.
 
383 can take advantage of a cam a 350 can't, without the penalties of worse idle, etc. At an extreme example, a 454 cam and a 350 aren't the same.

With Vortec lift maxxing out somewhere around .450", I think any head that comes out of the box without this problem is better, but the penalty (somewhat) is cost. But you get better components in the first place.

Call fast burn a "silly name", but the simple fact of the matter is, that "silly named" design outperforms the old heads hands down. If it was just a silly name, no one would be doing the same thing.

You'll also realize that some of GM's dealers are "modifying" crate engines and replacing the Vortec heads with AFR's. Again, the Vortecs *as cast* are not setup for anything other than really small cams. On that note, looking at the cam selected, isn't it a bit small for a 383?
 
Yeah, I mentioned that cam is rediculously small, yet DD says it'll make 400 hp. Bull$hit. True, a 383 can take a bigger cam than a 350, but the difference in dispalcement is less than %10. I listed the smallest cam I'd recommend earlier, which is still very small. I guess the issue is what rpm the motor will see most of its time at. The small torquer cams lose their appeal after 2500 rps, where bigger cams become much more effecient, and allow an increased static cr due to bleeding off of cylinder pressures at low rpms because of their greater overlap. This is part of the reason I like BBCs. I had a 396 that cam "on cam" at 3500 rpms, but still kills a 350 right off idle.

Vortecs can take .470 stock, this is small, but *maybe* big enough for a low rpm torquer. I would not buy Vortec heads if I really wanted a cam over .470. The benefits of "better components" really don't matter if you stay within the stock Vortec heads design parameters.

I certainly won't debate that the heart shaped "fast burn" chamber is the way to go, you'd be crazy to buy a new set of heads without this design, IMHO...

I did say AFR heads are the best choice, but worth $800 more for someone without a large income? I don't know... it would be nice to see hard #s on a motor built with Vortec vs. AFRs, but AFRs will allow a higher cr, so straight up its not a great comparison, but I'd really like to know. Maybe youll get your $800 back due to fuel efficiency if you go with AFRs, in which case I'd be all for it. (I'm working to get my Burb as effecient as a stock motor will allow).
 
Haha get your money back. :P

I'm at the limit on my Vortecs at just over .450", so I think there is either variation in castings or what people consider safe.

Only "problem" I see with the AFR's is that the combustion chamber CC is 68, while the fast burns come at 62CC. I'd want to use those to help select the pistons, as with AL heads, you are going to want as much compression as you can get.
 
The ensuing discussion after my last post is exactly why I started this post to begin with... I love the heated discussion without arguement about what is best to use in a 383 build and other motors for that matter... I'm glad you guys are showing me the ropes... I threw out that list of parts to start a few fires... and it worked. I didn't know what significance those parts had, other than the fact that they were expensive (minus the 400 cam) and after more reading, hell I may just rebuild the 400 with a giant cam and new heads and call it a day.

Seriously guys, after everyone is done with their input on this subject, maybe we should stick the whole post in the tech section for the proper components to use to rebuild a 383. I'm still looking for numbers, and still haven't decided on any specific parts except the GMPP Fast Burn Heads... but even that may change depending on what is said here in the coming posts. I chose a cam based on the description... I don't want a heavy lope idle, I want good fuel economy - yeah right dude... it's a 383 - and I want a smooth torque curve. I also want something that I'll eventually be able to drop a Fuel injection system on top of without too much pain and suffering. Yeah, it's going to likely start out with a Quadrabog or Holley, but after a while of getting 5mpg while towing, I'll want to upgrade to some sort of fuel injection. I'd imagine at some point, this 383 will be my offroad truck motor, and I'll get a proper tow rig to replace it... until then, this will be my bread and butter project truck...

My 356 is great... i can't complain about it at all... it survived a fire that literally melted the Intake and Carb right off the top of the motor, and as far as I know, it's still running strong... The 383 will get built after the restore is done on the 86, then the 80 will get converted to dually and the 383 will be dropped in.

Keep up the good discussion... oh yeah... I'd have put a bigger cam in on DD2003, but they all said they were made for street and strip... I chose a cam from the RV, Towing, Offroad category, and I couldn't find any that made better power. Still looking... Peace out guys...
 
If you plan injection later, the fastburns may cause you some problems. The LT1 intake *might* work on this swap, I'm not sure. The fastburn/vortec intake bolt pattern is pretty difficult to work around for injection swaps. TBI would be fairly easy I'd think, carbed to TBI adapter, but TPI is an expensive swap since there are only two "aftermarket" intakes that work with that bolt pattern.

AFR's may be a better choice if injection is in the future, or anything with a "standard" intake bolt pattern and runner configuration.

Bigger motors will take more cam and not sacrifice low end compared to the same cam in a smaller engine, I'd keep playing with the cam selection. If injection is in the future, keep an eye on the lobe seperation. Also take a look over at thirdgen.org, there are guys running fastburns and 383's with injection over there, I'm sure you'll find some posts mentioning the "computer friendly" cams they are running.
 
What size are the mains on that 327???? That may cause some issues....

Build the 400....Get a good set of rods/pistons, heads, induction and exhaust and blow that 383 away....
 
Hehe... I just pulled out the DD2003 again... and wow... the 400 whops the 383 hands down by almost 100hp and torque with the same cam and heads... BUT... the 400 is a 2-bolt main, and the 327 is a 4-bolt main... I don't know if the 400 can handle all of 500ft lbs of torque and 450hp...

I'm more interested in the posibility of a Diesel swap right now, so I may just sell the 400 and 327 blocks together as a package deal and get me a diesel.
 
I doubt the 400 is worth that much more power over the 383....

Just stud the 2 bolt main 400 and you are good to go.... The 2 bolt main 400 is actually more desireable than the 4 bolt version....
 
Alright, I give up, your DD program is rediculous. Youre not even about to order the parts for this motor? Don't waste my time.
 
PhoenixZorn said:
Hehe... I just pulled out the DD2003 again... and wow... the 400 whops the 383 hands down by almost 100hp and torque with the same cam and heads... BUT... the 400 is a 2-bolt main, and the 327 is a 4-bolt main... I don't know if the 400 can handle all of 500ft lbs of torque and 450hp...

I'm more interested in the posibility of a Diesel swap right now, so I may just sell the 400 and 327 blocks together as a package deal and get me a diesel.
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something is way off if you gained 100HP wiht 17 cubic inches
 
seriously... I got 459hp and 527ft lbs of torque with the 400 with GM Performance Parts head and Chevy 12-306-2 cam... I set the head size to 2.02" and 1.60", put a 750carb with high torque intake, and that's what I got... I know the cam is too damn small for a 400... I just wanted to compare the same parts.

The 383 got about 430hp and 496ft lbs with those parts...

I know my math is a bit off, but heh... that's a big enough jump... oh, since the 383 is bored .030 over, the 400 was as well on DD2003, so it's actually a 406.
 
dyeager535 said:
Not being argumentative, where do you see fast burn chambers on their site?

A bit bigger chamber (than the fast burns) though too.
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Actually It's on page 3 of their catalog, where it states that they invented the fast burn design for GM.
 
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