nyckcblsx

Well this is my first ever post so let me know how I do. I plan on building a high compression high revving 383 NA motor but I def need some help on it. I messed around with cam swaps and stuff like that that but this is the first time I plan on building from the ground up. I plan on using fully forged 383 stroker I-beam connecting rods flat top pistons tsp 233/239 112 lsa cam ls6 heads fast 102 3.43 rear end gears and all on pump gas. This car is going to be pretty DD with occasional street/drag racing so reliability, streetability(if that's a word) is definitely to keep in mind. Now what I don't is how do you even increase you cr? will this set up even work? what should be done to the heads? and what's the highest cr I can do that won't cause issues ? any input or changes I should do would definitely help. Also what power output would I be looking at so I could figure out what clutch to get. Thanks again everyone

NAVYBLUE210

11.0-11.5:1 compression with Good Tune and good fuel.
MMS 220 Cylinder heads probably worth at least 60 RWHP
over stock unported LS6 heads with that cam.
Good cam choice, A 114*+2-3* LSA would drive a little better DD
Without giving up very much.
Use 1 7/8" Long Tubes and a true dual exhaust.
I will guess the best numbers stock unported LS6 heads~420-440 RWHP
Quality CNC ported LS6 Heads ~460-480 RWHP
MAMOMOTORSPORTS 220s ~500-520 RWHP.
Attention to all the little details matter ie light weight clutch,flywheel,
Wheels all add up or subtract.
Start with the very best heads you can afford that is the Most
Important ingredient to your final results.
My .02
Good Luck

HCI2000SS

iTrader: (2)

NAVYBLUE210 pretty much covered it, and I'll that I run 11.5 compression on pump gas and no problems whatsoever

JakeFusion

iTrader: (7)

I'd toss the idea of a 383 and just throw a procharger on there with headers. It'll cost less, drive better, and make more power. And be just as reliable, especially with methanol injection and an upgraded fuel system.

Seriously.

DavidBoren

Let's not muddy the waters talking about boost. The OP asked specifically for advice on a 383ci stroker build, so let's talk about that.

Your build sounds solid. Take the advice about getting the best heads you can afford. Might look into some west coast cylinder head stage two ported 5.3 heads. They're a little on the small size, but still flow enough to support a naturally aspirated 383, plus the smaller valves increase velocity. And air velocity is your friend with a stroker motor, because of the high piston speed.

Tony Mamo is coming out with some mamo-fied afr 205's that would be absolutely righteous for a high compression 383. If you can afford it, that would be the best option for heads.

Compression should be raised by the piston, not reducing the deck surface. When you order your stroker kit, you tell them your combustion chamber volume and your desired static compression ratio... They should be able to do the rest.

11.5:1 with a spot on tune, and you should be one happy camper. Torque for days...

Darth_V8r

iTrader: (4)

If you're going to call Mamo, go MMS220. That head was designed for the 3.9" bore

JakeFusion

iTrader: (7)

I'm giving much more solid advice than you are. Look, I spent good money on heads/cam package already. And if I were to go with an NA bottom end, I'll be deep into the motor money-wise. And I won't have much to show for it. That's just a fact, because 500rwhp isn't doing much these days when you can buy a Camaro or Mustang with a lot more than than factory stock. This isn't 2001 when a 383 made sense.

Hell, I was looking at a big motor with a solid roller trying to hit 600rwhp. Do you know how much that was going to cost? And do you know how that would drive in comparison to a boosted setup that would make way more power?

If you want to do NA, be smart about it. A 383 is not smart. Go with a 416 at least. The LS3 block is better and it opens up much better head options. You're leaving at least 50rwhp on the table going with a 383. And the price isn't much different.

But, by not going boost, you're leaving 150-200rwhp on the table. Or, if you don't care about power, you need to look at total budget and goals. In that regard, a supercharger package on a stock motor, provides completely stock like drivability with more power and good reliability vs a built motor with 2618 pistons, brittle valve springs, and the like. And the one thing an NA car will never have is stock like manners at those power levels. It just won't.

I could have done boost from the get go, had more power, more drivability, and more of everything. For a lot less money. But I wanted the NA package. And I'm telling you, it's not worth it.

So, I stand by my statement.

DavidBoren

I fully understand your argument. Dollar per horsepower, the 383 doesn't make sense.

But the OP stated that advice was needed regarding the proposed naturally aspirated 383 stroker build.

The OP did not ask if adding a centrifugal blower to a stock displacement motor would be better. That wasn't the question... at all.

Forgive me for going against your advice, however sensible it may be, but it absolutely irritates me when someone asks a specific question, and everyone chimes in with irrelevant information. And, while correct, the fact that you can save money, make more power, and maintain better street manners with a stock motor and a centri blower is absolutely irrelevant to what the OP originally asked.

DavidBoren

All things considered, displacement, compression, and rpms are how you make naturally aspirated power.

He is adding displacement. Check. It doesn't matter if he's adding ALL the displacement possible. Yes, 400ci is possible. But 383 is still better than 346, so let it be.

The OP already mentioned that revving it up was the plan. Rpms... Check.

Compression was also mentioned and covered. Check.

Forged rotating assembly for high rpms is an excellent choice.

And, even if the OP decides to add boost, every dollar spent on the heads will still be beneficial. There are a couple boosted high compression motors on this forum, so nothing about the fully forged high compression 383 that the OP wants to build is keeping him from being able to add the centri blower later if he still wants more.

Darth_V8r

iTrader: (4)

I would argue that all things considered - airflow, compression, and RPM is how you make power.

If you put stock top end on a 383, you get a motor that makes more torque on the low end than a 346, but at peak power is very close.

Displacement will only determine airflow if the displacement is the limiting factor. If the heads and cam are the limiters, then you pick up torque due to the longer stroke.

Displacement determines potential power, but power is made or lost in the heads, IMO.

DavidBoren

Agreed.

Heads will absolutely make or break your build, and should be the main focus. And when it comes to cathedral port heads, Tony Mamo's afr heads are hard to beat.

If you can't afford that, then ported factory castings from west coast cylinder head, AI, TEA or the like will still do well.

KCS

iTrader: (20)

Looks like you're getting a little more than you bargained for with the replies, lol.

The compression ratio is simply the volume in the cylinder when the piston is at BDC divided by the volume in the cylinder when the piston reaches TDC. Anything you can do to increase the volume at BDC and/or reduce the volume at TDC will increase the compression ratio.

A 383 with flat top pistons and unmilled LS6 heads will be right around 11.4:1 so you should be good and won't have to mess with it much. Milling the heads, thicker headgaskets, or using pistons with a dish or reverse dome will alter the compression ratio. Online calculators, like this one will let you play around with those variables and see how it affects it.

It doesn't sound like you're too concerned about power, so I personally wouldn't recommend investing in aftermarket heads. It's probably not worh it for you. The heads you have are very capable heads when ported and paired with that cam you've chosen, should be a pretty potent combo without being too radical.

Sounds like you're on track to me. Keep us posted and feel free to ask questions along the way.

ahritchie

iTrader: (1)

I think you should decide power level and budget first....then let that dictate your stroker/346/LS3 decision. You are going about this build backwards looking at primarily the bottom end and focusing on 383 cubes...common newb mistake and mindset, not to be a dick.

As others said, power is in the heads (or boost) I was looking at a 383 but decided it would be overkill for my goals (performance and budget) and decided to go with an AI heads/cam package with MILD cam for excellent drivability, another newb mistake to keep in mind is buying a too big cam then end up complaining about lost drivability like some people!

svede1212

iTrader: (3)

There isn't one answer for everybody despite the impassioned arguments. I went the 383 route and didn't regret it. It drives better than my old heads/cam LS1. It's a blast to drive with a ton of street torque. I'm happy at around 500 RWHP as I've figured out it's a fool's game being the baddest dude on the street unless you have a big wallet or you have a very narrow set of priorities in life. My life is a lot more than cars. BTW How much is a stock 500+RWHP Camaro or Mustang?

Once you stroke if you decide to boost or spray or whatever you have a forged bottom end to give better reliability. Seeing as I could swap most of my parts straight over (FAST, TB, injectors, heads, LTs, etc) it cost me about $2,400 extra to stroke it. The engine was coming apart anyways and needed a machine shop cleanup of $800. Jake must have a line on a really cheap blower or turbo. My SCR is about 11:4 and DCR of about 9

DavidBoren

I don't see why anyone would have a problem with a 383, or a 313, or any other combination. The question was and is what should be done with the 383 stroker... It was never about whether or not it should be a 383 stroker.

If someone, anyone, wants to build anything, for any reason, and they ask a specific question, then you either give them a pertinent answer directly related to their questions, or you don't chime in.

Sorry. For the rant.

To the OP, your combo will do fine. You'll probably get 66-6800rpms out of it with a little work on the valvetrain, and the ls6 heads have good valves for rpms. The faster 102 will get you up there better than anything else, so you don't have any worries about your choice of intake. I like your cam. I think it's fitting for what you stated you want. If you want to squeeze a little bit more, get your ls6 heads and that fast 102 ported.

Have you thought about, or considered oil squirters? Bo law performance makes a set up for the ls1 blocks. You can use bmw oil squirters with check valves that don't open until oil pressure is up. And you can just use a gen IV afm/dod oil pump, ported ls6 pump, or any other increased volume pump. Just a thought. Long stroke is a lot of friction. And high compression is a lot of heat on those pistons, too.