Grumpy Help! Torque: Hot, Nasty Torque: FIRST Fuel Injection Intake SBC Build

NewbVetteGuy said:
Yea, at initial glance the cost jump from a 383 stroker kit to a 396 looks HUGE. BUT if you're looking at a 383 stroker kit with a forged scat crank, forged pistons, and forged h-rods, then the costs seem almost identical.

Longevity is SUPER important in my build as the car's been in my family for 40 years and I want it to last. -My car's L82 motor came with all forged components and if I'm replacing the bottom-end, I want to replace it with components of equal or greater quality.
I also like the idea that if I go with a forged bottom end, the engine can support spinning up to higher RPMs if I decided to also select valve train components (and a TC stall speed) that supported them, too; a nitros kit could also be safely supported. --I like the idea of having OPTIONS especially with the bottom-end components that really should last as long as possible. I might over-build the bottom-end and "waste" money there, but if I'm going to over build and "waste" money anywhere, I think it should be in the bottom-end and maybe the heads. I am literally gonna load up comp and give you my numbers and the info I have compiled



I definitely see what you're saying from a value perspective, especially if I set a rev limiter to 6,000 RPM with a 383- then forged internals is probably over-kill and about $1,000 "wasted"... It's a tough choice. One I won't need to make for a long time, I hope....


Adam
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Here is my ecact thought backed by hours with the desktop dyno crunching cash numbers and countless hours of research. My specs were done based around a camshaft with a solid design that not allot of people would enjoy on the street. I had to run a vacuum canister but maximized torque and hp out of 355 the cam is not to far off for my 383 build either. I gain nothing as far as peak hp but an extra 10hp on the lower rpm. 9 more peak ft/lbs of torque with the 396 and at the largest difference 16 ft/lbs around the 3000 rpm area. I could get a little better numbers by switching to a 1.6:1 rocker arm but $ per hp do not motivate me enough to do this. The extra cost is in not running a scat but a callies comp star rod thst gives the best chance of avoiding big mods like having to half fill the block cause you grinded into a water jacket. Or switching to a small base circle cam cause of clearance issues. Allot to consider then just the cost of the rotating assembly plus now increasing head flow issues my 195 heads will be close to becoming a choking point at that cid. Both spec out 500+ hp and 484 or 492 tq. I will skip the head ache, been down my options. Sad about probe going out of business they had a decent light piston for the money. If you are building a stout 383 for street application I would run scat 9000 put more money in the rods and pistons. And I would get the best flowing heads I could. AFR was the rage at the time I purchased I have not done any research lately as I am not in the market. But thats the real power adder. Building and matching your parts will make a screamer.
 
Strictly Attitude said:
Here is my ecact thought backed by hours with the desktop dyno crunching cash numbers and countless hours of research. My specs were done based around a camshaft with a solid design that not allot of people would enjoy on the street. I had to run a vacuum canister but maximized torque and hp out of 355 the cam is not to far off for my 383 build either. I gain nothing as far as peak hp but an extra 10hp on the lower rpm. 9 more peak ft/lbs of torque with the 396 and at the largest difference 16 ft/lbs around the 3000 rpm area. I could get a little better numbers by switching to a 1.6:1 rocker arm but $ per hp do not motivate me enough to do this. The extra cost is in not running a scat but a callies comp star rod thst gives the best chance of avoiding big mods like having to half fill the block cause you grinded into a water jacket. Or switching to a small base circle cam cause of clearance issues. Allot to consider then just the cost of the rotating assembly plus now increasing head flow issues my 195 heads will be close to becoming a choking point at that cid. Both spec out 500+ hp and 484 or 492 tq. I will skip the head ache, been down my options. Sad about probe going out of business they had a decent light piston for the money. If you are building a stout 383 for street application I would run scat 9000 put more money in the rods and pistons. And I would get the best flowing heads I could. AFR was the rage at the time I purchased I have not done any research lately as I am not in the market. But thats the real power adder. Building and matching your parts will make a screamer.
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The power difference between a 383 and a 396 is indeed not that much. If your engine is at 1.2 hp and ft lbs per cubic inch that's only an extra 13 cubes so only 15.6 extra ft lbs and hp; with 1.3 hp and ft lbs per cube for a really well designed engine that's an extra 17 ft lbs and 17 hp. But again, regarding a value calculation, as I'm already committed to going with a forged crank, rods, and pistons, it's almost a "free" 17ft lbs and "free" 17 hp.(And I want that 17 ft lbs) --The cost of a fully forged scat 383 kit I've seen and 396 kits are identical. I also like that you just don't see 396 strokers so there's a something special about them.

Regarding extra clearance -I am slightly afraid of that, but it seems that Scat's stroker-specific rods largely address that concern by having the shortest possible length bolt thread and caps and have a more compact design too so you can use stock base circle cams with up to an 0.060" clearance, too!

http://www.superchevy.com/how-to/engines-drivetrain/1102chp-396ci-small-block/

When I see the big crate engine MFGRs selling 396 strokers made from old SBC blocks with 2 year warantees, I start to think we're at the points where this is known enough that it's doable. (Although I think there's more clearance issues with my 2 piece rear main block than the 1 piece....) http://www.blueprintengines.com/index.php/products/bp-gm-crate-engines-landing/gm-396-main


I've already settled on Profiler 195 heads; they're the next best thing to AFRs and $400 cheaper https://www.profilerperformance.com/176-sbc-23-degree-heads.html 273 CFM starting at 0.500" lift.


Adam
 
I am not gonna tell ya what to build but if you go 396 use callies compstar rods look it up best clearance for a 396 build. You could avoid allot more issues that way.
 
Strictly Attitude said:
I am not gonna tell ya what to build but if you go 396 use callies compstar rods look it up best clearance for a 396 build. You could avoid allot more issues that way.
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Thanks, appreciate that tip.

Based upon your comments I started looking into it a bit more and I didn't realize that there's a much greater risk of hitting water with the 2 piece rear main blocks. I also didn't realize that SCAT says that the 9000 cast crank is good for 500hp and 7,200 RPM (I'm happy to intentionally to limit my build to 500hp and 6,300 RPM so cast may get me where I want to go and save me some $$$)... That's a good chunk of change that can be saved for Callies Compstar Rods (so I can worry less about hitting water), good forged pistons, and Total Seal gaskets...

-I really want to reuse the original block and if going from 383 to 396 is going to really increase my risk of hitting water (and it sounds like it will) -and will decrease my chances of being able to use a normal base circle cam, then I think I'll stick with a 383... Plus there's a lot more good data on good 383 "Recipes" then 396 builds.


I'm stubborn and I want people to prove their assertions, but I'm still teachable and willing to admit when I may have been wrong.
I'm not fully decided yet- if I can find a complete set of parts that makes success @ building a 396 pretty much assured, I might decide to go that way again.


Adam
 
I was dead set on a 396 but the difference in cost compared to power made me realize the money could be better spent on another part of my build.
 
if you think the extrs displacement between a 383 and a 396 will make a difference then ID consider a BIG BLOCK, think what a 496 cubic inch displacement and better flowing heads will produce
example
multiply 1.3 horse power per cubic inch by all three displacement levels
then realize the big block cylinder blocks FAR stronger than the sbc block.
and if your stuck on 396 displacement you cold built a kick as smaller displacement BBC

http://www.superchevy.com/how-to/0707ch-small-block-vs-big-block/
 
Grumpy said:
... in this case Id have suggested a bit more cam, and 40 lb fuel injectors
example
http://www.herbertcams.com/500-500-lift-225-235-dur-050-112-lobe-center/
and 1.6:1 roller rockers and a 3.54:1-3.73:1 rear gear ratio and a 383-406 short block and heads that flow well with long tube headers , with 3" exhaust (not 2.5")
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Follow-up:
Why are you right all the time, Grumpy?!?

I submitted all my new info to Mike Jones and he and you arrived and almost the same place regarding the cam recommendation.

He recommended his HR70375-72360-110
227/232 duration @ 0.050" -insanely close to your 225/235 recommendation.
But on a 110 LSA vs. a 112 LSA- I'd really like to understand the implication of a 110 LSA vs. 112 - I usually see wider LSAs on long runner intakes like this so I'm curious what the implication is. (Does the wider LSA give you a wider torque / power curve? (a wider RPM range during which you're in the power-producing "sweet spot?)

Is a CAM this big in a 350 really going to be ok, with my 2,300-2,500 stall TC? -I have no idea how to calculate what cam duration in a given displacement works with a given TC stall.

The other cam specs ended up .375" lobe lift on the intake side and .360" lobe lift on the exhaust side. -I loaded all the #s into DesktopDyno and because these heads really don't flow much more @ 0.600" lift vs. 0.500" lift, I only ended up with 1 more peak hp and 1 more peak ft lb of torque so I'm thinking that 1.5RRs is the way to go- as I think that buys me a bit less wear and tear / more longevity in the valve train vs. the 1.6RRs. (+1 hp and +1ft lb isn't worth longevity issues to me.)

I ended up with an estimated 469ft lbs @ 4,500 and 458 hp @ 5,500 in desktop dyno, but honestly I am pretty sure that I'm not modeling the FIRST intake correctly. I selected "Tunnel-Ram Manifold" and 660 CFM @ 1.5"HG for the intake; when I model a stock TPI intake I get 467 ft lbs @ 4,000 and 414 hp @ 5500. Based upon what I've seen out of this intake I'm guessing the truth is somewhere in between those two and probably close to the tunnel ram than the TPI, but either way I'm more than happy. All I wanted was 450+ ft lbs and 400+ HP at the flywheel. -Having said that I've got a stock bottom-end from 1979 so I doubt I'll see those results.



As an added update I ended up snagging some new-in-box Scorpion / Johnson short travel lifters that are capable of 7,500 RPM with the right springs and cam lobes; not that I'll ever spin anything approaching that. I'm just happy to know that the lifters won't be an RPM limitation.


Adam




 
Why are you right all the time, Grumpy?!?
Click to expand...
I'm not! but I learn from my mistakes and experience and keep notes,
Notes and records,on what works well and the mistakes other people make,
and I've always tended to do in depth research most of the time before I make changes..
.that results in hands on, EXPERIENCE , and having build well over 150 plus engines over the last 47 years helps (thats only about 3-4 a year)



http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

you might want to read through this thread and sub links, the 110-vs-112 will be a very minor change the 110 LSA will provide an almost un -measurably narrower torque curve , and slightly rougher idle, and in theory a gain of 2-3 peak hp, with almost no other change you'll see vs the other cam the slightly wider 112 LSA, provides a bit wider torque curve and smoother idle.
on the street Id go the 112 LSA route but its really a toss-up I doubt youll feel the difference
 
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Comp Cams prefers to use a 110 degree LSA on most of their cams. Crane prefers 112 degrees.
 
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