My 383 build plans.

[othtim]

(wall of text incoming)

Hi. So I'm planning on building a 383 this winter.
I built a 350 last year - vortec heads w/ a mild cam.
Now that I'm used to it I want more power 🙂

My goals for the 383 are:
Power peak around 5300-5500 with a flat-as-a-pancake torque curve. I'm looking for 400 ft-lbs between 2000 and 5000.
I'm looking for a cam to make around 450 ft-lbs and 420 hp minimum, and still be streetable and have a quiet idle.
Shift between 5300-5500.
This engine will be street driven, and I work my motor pretty hard. Seeing as a cruise almost every night in the summer, and go to the track many fridays, the motor will see 5500 RPM many times per day. Often the motor will see 15-30 minutes of driving at RPMs above 2000. So I need some amount of toughness.

I am looking for ideas and critiques on my build plan.

My plan is this so far:

I am going to get my 350 short block rebuilt 4-bolt. I will be getting the mains align honed for use with ARP main bolts. I plan to use a SCAT 9000 cast 383 crank, with forged rods and quality hypereuctatic pistons. I am interested in suggestions on hyper pistons to use - I was planning on using the scat rods that are already clearanced for stroker applications. All rod hardware will be ARP. I was planning on getting the machine shop to assemble the short block, then measure the deck height and mill the deck till I get around 9.8:1 compression.

I am looking for head suggestions. It will be a 383. I'm only familiar with 350s, I've built a few. I know a 170cc head like the vortec is a great head for a 350. However I dont really know what heads are good for 383. I'd like an aluminum head if possible, but I will be interested in an Iron head that is the right price. So far, I've been looking at the GMPP Vortec Aluminum 210cc heads. I've also been looking at the RHS pro action heads.

The most important thing to me is streetability at lower RPMs. Peak power is good, but I'd like a flat torque curve from 2000 up. Looking at around 2300-2500 stall. I want a mild idle, not choppy, possibly with a very very slight lope. At this time, I've beeen considering roller cams to get me where I want to be.

Any advice or criticism is welcome.

 

[othtim]

I forgot to mention, I've also been looking at the 180 Bowtie Small Port Vortecs. THey look awesome.

 

[khan0165]

I don't have a 383, but the cam in my 350 is about as wild as you want for a summer daily car. So I would suggest something similar to achieve your HP numbers.

it's a 282S, solid flat-tappet. 0.282 advertised duration, 0.236 duration @ 0.050, 0.495 lift. It's a 110 deg LSA

that being said, solid cams are a nightmare to lash, so stick to hyrdraulic to keep things simple. You should look for around 0.235 to 0.240 duration, beyond that will affect street calmness. If you shoot for 0.500 lift, and use 1.6 Rockers, you'll have a mean valvetrain.
Just makesure your valve to piston clearance is good, and have the pushrod sleeves clearanced.

... you can expect over 450hp, and close to 500ft-lbs with a good intake and carb... don't be afraid of single plain intakes, and a big 850cfm carb... if you tune it right, it'll take all the CFM you give it.

 

[othtim]

I'll be RPM limited with this motor as I will likely be using a q-jet and a low-rise manifold for hood clearance under the stock hood. So I'm kind of shooting for max power and torque 5500 RPM and below. Most single plane manifolds are out due to hood clearance issues. Hydraulic-roller will be the way I'll be going.

Anyone have any suggestions on heads? I'm more-or-less set on the bottom end specs. Just looking for a good piston recommendation and head recommendation. Also, anyone ever used ceramic coatings? I've been considering getting some ceramic coatings done to (potentially) improve performance. They are within the budget at this time.

 

[dogsht]

He may not be an engine builder but you might check out JBreu's ride. He has a small block stroker build that you might get some ideas from. His may be a little more aggressive than what you are looking for but its a real driver not just a toy. Maybe he will see this and chime in. Or PM him I bet he would be happy to help.

 

[drogg1]

I like your bottom end specs so far. For pistons, knowing the benefits of going forged, I am inclined to direct you that route. However, hypereutectic pistons will probably serve you well given the low compression and ideal RPM. assuming you will be using a 6.0 inch rod I would recommend a flat top like this:

http://www.summitracing.com/parts/UEM-KB122-030/

Since this is a 383 and not a 350, to achieve your desired ~9.8:1 compression ratio, you will have to use a 72cc head.

Decently useful compression calculator:
http://www.kb-silvolite.com/calc.php?action=comp

As for heads, I would go with something like 190cc runner. Keeping the runner size down will give you that torque you're seeking.

I've heard good things about AFRs and would probably run them if I could afford them. RHS's and Darts also seem to flow well. Any of the bigger names will suit you well as long as you don't go to big on the runner size.

I've also heard good things about those vortecs. 180cc would probably be a large enough runner size.

Also, if you think you're up to it or have the means to pay for it, the vortecs could use a simple clean up port and polish and probably net you very good results.

I don't know if you've already made your cam selection, but if you're looking for a smoother idle, I would make sure you don't pick a cam with too tight of an LCA. I would also recommend looking up how the LCA (and thus the overlap) of a cam effects engine performance and idle quality if you are not familiar.

I hope some of this helps.

 

[chevy2480]

With a 420hp min. You will be pushing that scat 9000 crank to it max hp rating of 500hp i would consider a better crank.

 

[othtim]

Why would I use a 6" rod. I dont see the benefit of it. And 6 inch rod kits usually drive the price of the kit up, and make for smaller (weaker?) pistons. What are the advantages that would make me want to run a 6 inch rod?


ANd those are exactlky the kinds of pistons I want. 2 valve relief, with a good flat quench area.

I like your bottom end specs so far. For pistons, knowing the benefits of going forged, I am inclined to direct you that route. However, hypereutectic pistons will probably serve you well given the low compression and ideal RPM. assuming you will be using a 6.0 inch rod I would recommend a flat top like this:

http://www.summitracing.com/parts/UEM-KB122-030/

Since this is a 383 and not a 350, to achieve your desired ~9.8:1 compression ratio, you will have to use a 72cc head.

Decently useful compression calculator:
http://www.kb-silvolite.com/calc.php?action=comp

As for heads, I would go with something like 190cc runner. Keeping the runner size down will give you that torque you're seeking.

I've heard good things about AFRs and would probably run them if I could afford them. RHS's and Darts also seem to flow well. Any of the bigger names will suit you well as long as you don't go to big on the runner size.

I've also heard good things about those vortecs. 180cc would probably be a large enough runner size.

Also, if you think you're up to it or have the means to pay for it, the vortecs could use a simple clean up port and polish and probably net you very good results.

I don't know if you've already made your cam selection, but if you're looking for a smoother idle, I would make sure you don't pick a cam with too tight of an LCA. I would also recommend looking up how the LCA (and thus the overlap) of a cam effects engine performance and idle quality if you are not familiar.

I hope some of this helps.

 

[drogg1]

I just assumed a 6 inch rod. There's benefits to a shorter rod and benefits to a longer rod. Shorter generally leading to more horsepower. Longer leading to more torque.

However, it doesn't really matter as I would recommend the same piston. It was just for reference as a piston with a 6 inch rod is different than one with a 5.7 inch rod.

edit: Just was looking around some more and in comparing pistons that were same brand/style/cc, the 5.7 inch rod pistons may be heavier. While not critical, something to consider I guess. Although, they are cheaper across the board and have far more variations to choose from.

I don't mean to argue either. Just to share what I've seen.

 

[othtim]

Realistically, how happy is a 383 with revs? That is one of my biggest issues. I'm considering a 350, if people feel that it revs better. The actual block is set, but really everything else on the short block has to be bought. So really this should be titled "my 383 or if it wont work, 350" build. I rev the piss out of my motor, all the time, even though it's only 5000-5500 rpm. Every day this car will be hitting max RPM - multiple times per day. Extended operation at 2500-3000 RPM, like, 30 minutes to an hour a day most days of the week. How much more load is a 383going to be than a 350? as far as accelerated wear on the motor.