Utinator

I tried searching, but I didn't find much info on the 383. I have previously heard that they are usually disappointing. I wonder if that has something to do with the parts (heads/cam/intake) that were available way back when the 383 was "the thing" to do. Now, everyone just adds boost. I live in Texas, so I don't need to add anymore heat under the hood. I would prefer to keep everything looking "natural" under the hood. I have been thinking about building a 416, but I'm wondering if a 383 would be sufficient. I have a 383 build in mind. Please let me know how you think this combo will do:

383-LS1 -->11.5:1 compression
Promaxx LS3 (small bore) heads-->2.08 intake / 1.6 exhaust valve ---->these flow just over 350 cfm.
cam ~ 238/247-114 (.625/.600)
stock LS3 intake (lightly ported)
full accessories, full weight SS Camaro, 6L80e (3600-4k stall), stock 10-bolt

What HP do you think this will make at either the crank or wheel (your choice)?


BTW, I did see the Richard Holdener video of the 383 that made about 603hp. That was with cathedral port heads/intake, but I want to use the LS3 intake that I already have. The Promaxx LS heads appear to produce similar or better airflow than the TEA ported 243 heads Richard used. I'm just using his video for comparison.

jhshnh

I don’t know anything about those heads but I will certainly say for 600 hp from a 383 you’re going to need more cam. I’m not familiar with ls3 intakes (I understand they’re excellent from the factory) but you may need a fast. Headers certainly need 1 7/8” x 3” and one guy on here years ago did a dyno comparison with 1 7/8” x 3” vs 2” x 3” on a mild 383 and the 2” x 3” made more power.

600 hp is certainly not out of the question it’s more of have the entire combo working together.

Utinator

I have 1-7/8 headers with 3” pipes.

The Fast LS3 intake only makes about 5 hp more than the stock LS3 intake. It’s not worth an extra $1500.

I was hoping to not go too big on the cam, but you might be right. I think it will get pretty close to 600hp with a cam like that. I think that’s pretty close to what Richard Holdener used. I use his tests as a comparison, because they are repeatable. Like I said before, he used cathedral ports, but the rec ports I listed above provide just as much air. The Promaxx heads have a better valve angle too.

jhshnh

Richard definitely knows his stuff. I’ve always wondered what small bore rec port heads would do on a LS1 block so I’m definitely interested. Just my opinion, since your combo isn’t a common setup I would call Tone Mamo or Cam Motion and let one of those guys spec you a cam. They’re are some very knowledgeable engine builders on here, maybe they can help, because I doubt there’s an off the shelf cam that’s optimized for your setup.

Utinator

I watch a lot of Youtube. Lol. I found an Eric Weingartner video where he was talking about the Promaxx heads. He shows the flow numbers at the end. They are pretty impressive for as cast heads. The small bore flows enough to make 700 hp (in theory). That would be more than enough for me. I have thought about putting them on my car now, then reusing them on a stroker build later on. They would work well on a 383 or 416. The 416 would make more hp with the big bore heads, but I think the small bore would be close enough for me.

Forcefed86

iTrader: (4)

Holdners stuff is inflated a ton. I wouldn't look there for examples. You need to go big everywhere for 600hp+ NA. Or simply stop fighting what makes the most sense, and run a small turbo. It will be half the price with twice the potential.

Put a little 78mm in the back where the muffler is. Route your factory exhaust to it. Run one 2.5" pipe to the front and through a smallish IC. You'll be set. 600++ like its nothing on all your factory parts. No reason to bore/stroke or use aftermarket rotating assy with a 600 crank hp goal. if/when it pops drop an SBE 5.3 in and go. "building a motor" with those power goals makes no sense from an economical point of view. I get it if you just want to do it for fun though.

What fuel is available? If you can run E85 you can go higher on base compression. Or skip the intercooler on a little 600chp turbo build.

Utinator

Yeah, I get it. Making power with boost is easy. I just don’t want to chop up my car to make a turbo kit fit. The turbo kits aren’t cheap either. I can build a 383 for about the same price as a turbo kit.

grinder11

iTrader: (1)

I can guarantee you're correct about more cam. Without FI or a wilder cam, not gonna happen. I have a built LS7, with Cammotion by Futral cam. 238°/242°, .638" lift I, .646" lift E., on a 114° LSA. 90mm TB, LS7 intake. Made 617hp@6,300rpm, 565lb/ft torque@5,000rpm. Running 1-7/8" Kooks LTs. The OP can hit 600, but it will be mostly upper mid range, and up power band. Going up only 37 cubes from stock LS1, but expecting a 250hp gain N/A is a tall order.

slowride

iTrader: (3)

I followed Tony Mammo back in the day (2006 range) when he built his 383 that went from engine superflow dyno to dynojet etc. For some reason all the old posts from before 2020 or so have been purged (mine included), but he made something like 620-630hp on the engine dyno gross which all machine shop dynos across the country use and maybe 515-520 dynojet in a manual vette. Your cam would probably put you in the same ballpark as my old setup which was a 383, 11.83:1, cnc 243, 238 242 114+0 cam, ported fast 90 it made 501whp in my manual c5 at speed inc. The year before my car made made 482whp on a ls6 intake with cats and a cooler fall day in the shop (same day my friends cam only 228 232 114+4, bolt on c5 made 397whp). Hard to say with the 6l80 trans and if the converter is locked up etc.

jhshnh

https://ls1tech.com/forums/generatio...s1-530whp.html

Here’s a recent Mamo 383. I’d say this is 600 at the crank.
I have Mamo heads, Mamo ported MSD, and a Mamo spec’d solid roller on my sbe LS1. Almost ready for dyno time.

NAVYBLUE210

I am actually looking at the 2006 Engine Masters Magazine, hard copy( I know right, everyone said recycle the mag it will always be available on-line, lol)
Tony"s 383" was the bogey for my build. Tony"s 383" made 611 HP @ crank on Westechs Dyno & 530 RWHP on multiple Dyno Jets ~6600 RPM.
AFR 225s 320/250 cfm @ .600" on 3.90" bore, Comp Solid Street Roller (.016" lash hot) 242*/248* 114*+0* Ported Fast 90, 11.0:1 Comp, 1.75" headers.

My 393" Big Bore 4.175", MMS LS3 Heads, Fast Mid_Length Runner, Cam Motion LLSR (.008 lash for comparison ) 243*/249* 115* +3* (HR ~237*/243*), 11.7:1 Comp, 1.875" AR LTs.
Made 690 crank HP at the same Westech Dyno 7100-7300 RPM & ~ 590 RWHP @ 6800 RPM on a hub dyno in Mn6 C5.

I think the ProMax heads are about ~240 CC, with a legit 350 cfm @ ..600 on a 3.90" bore you have more then enough cfm for 600 @ crank
With at least 11.5:1 comp, closer to 12 even better, Well ported/rod-mod intake with 1.875" headers should not prevent reaching 600 crank.
Mid -runner Fast would be worth 15-20 spinning 500+ rpm higher, but not needed.
Definitely consult with Cam Motion but something like 235*/243* .624/.612 114*+2* would get the job done, and still drive well on the street.
Just my .02

slowride

iTrader: (3)

Tony actually did a cool test on that 383 and use the same heads/cam as his did on his stock bottom end 5.7. That cam was a 224 228 114, heads were the 205s which was a cool comparison to see how the larger cubes reacted with the same top end as the 347, in the end the peak power was pretty close just moved it down about 500rpm as torque was up I think 40-50 if I remember right. I think he almost made 600 crank hp in the 383 with a 234 238 camshaft also before going to the solid roller.

jhshnh

So as you can see, it’s doable for sure. You just need the right setup for your combo.

01CamaroSSTx

iTrader: (3)

Like to think a 12.5:1 LS370, 238°/246° .632/.632 111+3 not too far off from 500whp. But I have my doubts when compared to an LSX427 with a bigger cam, FAST intake and LS7 style heads that's putting down 540-550 whp on 93.

Forcefed86

iTrader: (4)

That's not even remotely true. You can weld your own turbo kit easily for less than 1/3rd the cost of and NA 600hp combo. A billet 78/75 is $250. Use the oem exh piping routed to a T4 flange. Then buy cheap ebay mild steel 2.5" piping/coupler kits for the cold side. Its really not even a comparison cost vs performance wise. The LS1 also is the weakest of the blocks with paper thin cylinder sleeves. I wouldn't put good money into an LS1. Go to a 4" bore if you want to go NA.

Doug G

3Pedals did a build a ways back... I do recall there was something with the rocker/valve tip geometry though, IF I remember right.
So, I'd say it's do-able

HP 648/526 TQ
30Kmile LY6
850 Mighty Demon on a 1" open spacer, on a L92 VIC Jr
Edelbrock 1 3/4"-1 7/8" headers
head cut for 11.0:1 compression
OEM pistons flycut .070"
Bret Bauer spec'd cam and valvesprings, pushrods 23X/25X
oem lifters
93 octane pump gas
31* timing, verified with a pinned ATI damper and timing light
12.8 A/F

Utinator

I can’t weld. Most of us can’t weld. Just like most of us can’t forge rods and pistons. Sometimes the only option is to buy the parts you want. That’s why a turbo and 383 would cost me the same. I just added it all up last night. I can build a 383 for about $6k gross. I can sell some parts that come off, so the net cost would be closer to $5,500. The ac retaining kit from Huron Speed is about $6,623.00 with the cheapest options. To install the turbo kit, I would have to hack my front end into pieces, and piece it back together. I really don’t want to do that.

Forcefed86

iTrader: (4)

That's crazy talk.

A Harbor Freight mig is $89! $130 for a nicer one! (don't forget that 20% coupon!) Either way, both are more than adequate to weld up a hot and cold side. I use 110v mig and have made a dozen+ kits. Some have more money than time... I get that. But don't say you can't weld. Anyone can weld. Just a matter of time/effort. I couldn't weld either... so I bought one and welded with it... now I can weld.

I don't know where you get your information from but I can't think of a chassis you'd have to butcher to get a 600hp turbo kit on.

Either way You can add a remote turbo (or have one up front) for WAY under $6k, including the cost of the welder and materials. That's my point. A cam and springs would help, but really you could leave the motor alone. Depending on fuel, an intercooler is even optional. I make well over 600 on a cam only SBE JY 5.3 with no IC on E85. You can make 600hp on decapped stock injectors, paired with 2 AEM400 pumps. You can even mail the ecu out and have a tune put on it. I just did this exact same thing for a bud at work running a 1500 series truck. nothing was butchered and no accessories lost etc.

Simply saying take a look at the forced induction section of this forum. People think they need a lot more than they actually do. Turbos are easy. NA power is MUCH harder and more expensive.

Anyway I won't comment anymore, but if you have any questions feel free to ask. I was going 8's making 900+ with well under 6k in the motor. 600 is a breeze.

1988montecarloss

iTrader: (6)

westech dyno has always been happy so Holdeners tests arent the most accurate, what you have spec'd out there will make high 500's crank but wont break 600

i would sell that motor and start over with a 6.0/6.2 and factory rec port heads for basically the same results at way less cost or upgrade intake mani, sbe 6.0/6.2 will break 600 n/a with the right parts

Utinator

I kinda duplicated one of Richard's tests 2 years ago. It was his truck cam video, where he tested all of BTRs truck cams on a 5.3L (LM7). I used the same 706 heads, stage-2 cam, and TBSS intake, but I had stock exhaust manifolds and flat-top pistons. Richard's test engine had headers and dished pistons. Those were the only 2 differences in our motors. My combo made about 5hp more than Richard's. If I had headers, my engine would have made much more than his. That's why I say his tests are repeatable. I know every dyno could vary a little bit, but Richard Holdener's results are realistic and repeatable.

I have also considered selling my LS1 and starting over with a 6.2L. A cammed 6.2L would be much cheaper, and probably get just as close to 600hp as a 383. The "problem" is, I already have an LS3 intake and a 4" crankshaft. I really want to use both of them.