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Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 1:41 pm
by RevTheory
gnicholson wrote: ↑Mon Apr 16, 2018 1:07 pm
If you want low rpm torque you need to think small cam on a tight lsa .108 at most and 270 adv duration. If i were towing i would go 106 and 262 to maximize torque at 2500 rpm
I did a 383 many moons ago that used untouched 180 cc Pro Topline heads at 10.0:1, Performer RPM Q-Jet intake with a Q-Jet from The Carb Shop, Comp XE, hyd/flat 270, 227* at .050 on a 107 with 1.6 rockers and long-tube headers and it was good for 455 ft/lbs at, if memory serves, just shy of 4,000 rpm. I think it peaked hp at 405 somewhere around 5,500 rpm; under that, if anything.
Edit: That was a no-frills build by the way. No windage control, no intake heat management, fat rings, etc. Just a clean engine build.
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 4:56 pm
by dfarr67
Find an old Caddy 500.
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 5:00 pm
by Orr89rocz
Get a tuned port injection intake, it will get over 450 lb ft fairly easily. I had cam L98 build do 350 wheel torque thru the auto trans which is probably 425 crank or better.
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 6:22 pm
by plovett
My opinion is that 500 ft/lbs is not possible given the parameters listed.
I think 460-470 ft/lbs might be possible with a high compression pump gas combination. I don't think so with 9:1 or so.
I think 500 ft/lbs might be possible with a very high compression race gas combo.
For 9:1 compression I think 440-450 ft/lbs would be fantastic.
JMO,
paulie
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 8:47 pm
by gmrocket
316 cubes, flat tappet, just over 10:1, factory junk mid 80's iron pollution heads, long tube 1 5/8" 2 1/4" pinch collector and mufflers, E Brock dual plane, 6.25" rod short stroke 3.385", 235@50 105 LSA in +4 ....438TQ
If it didn't have to pull to 6500 I would have gone 10 less on intake and it would have maybe made 450
Chevy 383 with all the intakes, headers and other stuff available, can't see why you can't make high 400 TQ
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 9:00 pm
by 77cruiser
Don't think it will happen, unless you have more ci.
https://www.speed-talk.com/forum/viewtopic.php?f=1&t=43195
Remember this one?
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 10:54 pm
by mtmvette
I'm beginning to think im going about this the wrong way. Smog heads, small cam, is that the trick? I know forced air induction will do it, but I want to keep it simpler... And I cant afford a turbo. The original 350 in my truck really struggled up the hills, granted it was tired but it was downright embarrassing. Pulling the trailer with my sons 5.3 vortec was a little better but not much. I would like to keep the truck original looking as well. That is one reason I want to stick with the SBC. Still confused.
Re: SBC 383 500ft/lb torque build
Posted: Mon Apr 16, 2018 11:40 pm
by gmc406
Is a 406 outta the question? Or even a 420?
Maybe just go with a big block 454? But I know you want to keep it looking original.
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 1:28 am
by englertracing
Screw that,
Seriously I'd rather do it with a screw and meth/water injection
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 1:32 am
by englertracing
Newold1 wrote: ↑Mon Apr 16, 2018 12:23 pm
This would be my build suggestion and it will get you to 500ft. lbs and 385 HP out of a 396 inch engine. 4.100" bore with a 3.75" stroke with a 6" budget rod and static compression of 10.5 to 1. A hydraulic roller camshaft with 215 duration @50 on intake, 220 duration @50 on exhaust with a 110 lobe center and an 114 LSA with lifts on intake and exhausts both at .520". Vortec heads with 2.02 intake with slight bowl cleanup and proper 5 angle valve throat. 1.65" exhaust with good seat and radius throat finish under seat. A good aftermarket cast crankshaft. a nice set of 4032 forged pistons with 1.5, 1.5mm and 3.0mm standard tension top moly rings and a piston clearance of about .0045" and nice 12-20 RA bore plateau finish. Put a nice dual plane air gap intake manifold and a well built either quadrijet or 650 Holley carb and a good billet HEi with a MSD spark control and exhaust with a nice set of street tri-y 1-5/8" headers into a 3" collector and a nice 2" exhaust pipes thru a nice set of Spintron SS mufflers and you've got the the best truck small block high torque levels between 2500-3500 rpms on pump gas you could want. None of the above is exotic or high dollar, just good simple well matched components to get you the torque and HP you've requested with your post. This engine properly tuned will provide nice cruising manners and mileage with a smooth easy foot and when you want to stretch it's legs it will run!
What's with the 114lsa
How about something like 108
And I think the compression is too high for towing things up hills.
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 2:07 am
by bigmike
Don't see it working out if you look at the gm HT383 crate engine it can still only hit 444 LB-FT @3000 RPM with iron vortec heads and Hydraulic roller cam.
Something like a GM HT502 crate engine well get you to 541 ft/lbs TQ @ 3200 RPM with a compression low enough for towing.
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 9:54 am
by F-BIRD'88
bigmike wrote: ↑Tue Apr 17, 2018 2:07 am
Don't see it working out if you look at the gm HT383 crate engine it can still only hit 444 LB-FT @3000 RPM with iron vortec heads and Hydraulic roller cam.
Something like a GM HT502 crate engine well get you to 541 ft/lbs TQ @ 3200 RPM with a compression low enough for towing.
This is much more reasonable and U doable.
A 9:1 383 will need mild supercharging to hit a real deal 500 ft/lbs in do able truck towing motor form.
Get a 502 BBC
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 10:45 am
by CamKing
PackardV8 wrote: ↑Mon Apr 16, 2018 11:42 am
who'd be comfortable with putting a 12:1 383" in a sustained WOT pull?
That recommendation is only for running E85.
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 10:54 am
by englertracing
my new phone wasn't cooperating and deleted my post last night.
I don't think crap stock heads will help anything.
Best bet is to find the smallest and most efficient aftermarket heads you can find.
You want something with a small port that flows well for its size, stockers are small but don't necessarily flow well for their size.
You want something with a nice modern chamber.
More cubes are your friend, maybe you can make 4" x 4" work? 402"
If you can wrangle up an aftermarket block you can do 4.125" x 4" 427"
Use pistons with a modern 1mm 1mm 3mm ring package, not old junk.
For the camshaft, you want a short high lift hydraulic roller, with a tight LSA, one of Mikes IR cams would serve you well and whatever he specs is sure to be dynamite.
Headers should be small long tube 4-2-1, not short thorley type Tri-y
if you get it to 427" you might be better off with a small single plane instead of the dp manifold
have someone build a carburetor to suit your whatever ends up being your combo, and not a small one! maybe something with annular boosters
Re: SBC 383 500ft/lb torque build
Posted: Tue Apr 17, 2018 10:56 am
by CamKing
Here's the specs on my 355 SBC in my boat. a 383ci version would give you 475ft/lbs. Notice the 112 LSA
355 SBC
10:1 compression
ported 492 heads
Performer RPM
Holley 600cfm "top-loader"
LS firing order hydr roller cam: 216/220 @.050" .340"/.340" Lobe Lift, 112 LSA, 108 ICL
1.6 rockers
Morel #4602 lifters
PAC 1218X springs
RPM---TQ--BHP
3200--439--267
3400--443--287
3600--445--305
3800--444--321
4000--443--337
4200--440--352
4400--440--368
4600--441--386
4800--441--403
5000--432--411
5200--422--418
5400--412--423
5600--400--426
