Ultimate torque thread?

[FE Jonny]

How can I make the most torque at the lowest RPM? I know the basic small tube header with long primary and long runner injected intake stuff but what about cam timing and other goodies? I want to make the most as low as possible and wondering what could be done. I have Performer heads with a Stage II prep and one of Jays intake adapters that I am going to use for a Injected intake. I am looking at the Trick Flow R series but should I get the Box R due to the intake is designed for 350 cubes or the R series long runner. I already have the lower and a 90mm throttle body, I haven't decided on the upper yet.

[blykins]

Big inches, low camshaft duration, good head flow. 

I've built lots of FE engine packages, but have no experience with the hybrid type of build that you're dealing with. 

Look through the dyno results here on Jay's forum and you can get an idea of what does what.  What do you consider "ultimate"?

[ScotiaFE]

I lifted this blurb from the Comp site.

EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA)
 
Tighten (smaller LSA number)           Widen (larger LSA number)
Moves Torque to Lower RPM                        Raise Torque to Higher RPM
Increases Maximum Torque                         Reduces Maximum Torque
Narrow Power band                                     Broadens Power Band
Builds Higher Cylinder Pressure                    Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock                 Decrease Chance of Engine Knock
Increase Cranking Compression                   Decrease Cranking Compression
Increase Effective Compression                    Decrease Effective Compression
Idle Vacuum is Reduced                               Idle Vacuum is Increased
Idle Quality Suffers                                      Idle Quality Improves
Open Valve-Overlap Increases                      Open Valve-Overlap Decreases
Closed Valve-Overlap Increases                    Closed Valve-Overlap Decreases
Natural EGR Effect Increases                        Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance             Increases Piston-to-Valve Clearance
 
http://www.compcams.com/Pages/413/cam-timing-lobe-separation-angle.aspx

Judging from this comparo I can't see any benefit of moving the torque to the basement.

[FE Jonny]

Well I started with a Survival 445 stroker kit, then had Barry do a stage II prep with T&D race rockers. I have a roller cam but will more than likely change the cam from what I have now to something more low end oriented. I know moving the cam will change the torque curve but I am not sure where and how much to maximize low end torque. My pistons are 10:1 survival coated flat tops with Molly rings. I am just wondering mostly cam wise and intake wise which direction to go? The long runner R series is rated for lower RPM but is also designed for smaller cubic inches, the Box R is rated for higher RPM but has larger and more acessable ports for porting should I need to open it up. Another member used the R series intake with one of Jays adapters a while back but I never saw the finished project?

[ScotiaFE]

What cam do you have now?
And you want to put a smaller cam in correct?

[FE Jonny]

What I am after is low speed power for negotiating steep terrain and and crawling. Spinning the engine to 6000 RPM is not really going to help me much, I need all the low end I can get as I am moving a big truck with a lift and big tires with 3.70 gears. I am also kinda hindered for low range gearing as I am using a NP 205 transfer case, it is a bullet proof gear driven case but has an anemic 2:1 low range.

Yes I am going to change the cam, it has a power band of 4000-6000 RPM right now so has to go.

[blykins]

I would aim for something in the 210-215 range at .050".  With that low duration you can go tight center without adding a ton of overlap.  I would do a 107-108 LSA.  Need a lazy lobe to help with the cylinder pressure and depending on the valve job, prob around .550" lift.

[FE Jonny]

I got an awesome flowing head for lower lift, the valves are back cut and seats are all done up by Barry over at Survival. Also he replaced the guides and installed 11/32 stem valves instead of the original Edelbrock 7/16 stem. The bowls and guides were smoothed over also. I was thinking somewhere around .500 to .600 lift but honestly I never have built an engine for low RPM, I was always going for top end. Right now my cam is just under .700 intake/exhaust.

[ScotiaFE]

I find it hard to believe your power band is from 4000 to 6000 rpm.
Probably somewhere around 2000 to 6000 and probably pretty flat cause most 390
strokers are torque monsters.
You would need to lay out your gear sets.
That's were you will make huge gains in using your torque.
What trans and gear set?
If auto what kind of converter?
Tire size?
It's all in the gears.

[FE Jonny]

6.00 first, 1:1 fourth T19, 3:70 gears, NP 205 transfer case 2:1 low range , 33/12.50 tires or maybe 35s. 2800-3000 cruising speed. I would like my power band from idle to 5500 but like a 2000 sweet spot. I am injecting so duration can't be too high, and l am looking for about 550 lift. I am thinking about 110 separation to keep idle smooth and have vacuume. Any closes I would have a crappy idle and no throttle response. I was looking at some cams that Barry has but nothing quite like I am looking for, maybe I'll give him a call next week and run some ideas past him.

[ScotiaFE]

At these numbers you have a low gear ratio of 44.4 to 1.
At 2000 rpm you would be traveling at about 4.4 MPH.
Some of those crawlers like to get down to 60 to 1.
One issue with lugging the engine down, especially a bigger engine is detonation.
That will beat the engine up more than anything.
The 10 to 1 comp at low speed under heavy load will detonate.
I would recommend a steeper rear gear, keep the rpm up a bit
and use the gobs' of torque you have to your advantage.
A 4.56 rear gear will get you to 54.72 and put you into some serious stump pulling giddy up.
At 2000 RPM you would be zipping along at 3.6 MPH.

[blykins]

Take a look at the other thread about the hydraulic roller camshaft.   The 482 that I built for "TJ" will lug around a 10000 lb trailer at idle, but yet peaked at 5200 rpm on the dyno.  Now granted, that was a 482 inch motor, but the characteristics could be applied to a 445.

Also, keep in mind that a 110 LSA sounds like it would be more mild, have more vacuum, etc., but you need to look at the overall picture of the cam.  I could probably spec a grind that at 107 or 108 LSA, would have more vacuum and a smoother idle than another cam at 110 LSA.  You look at total amounts of duration and overlap...not just focus in on LSA. 

Howie, you have a good point about lugging a higher compression engine, but I think this is the guy wanting to run E85.

[FE Jonny]

Yup going E85 with 13:1 compression and SN95 PCM with a tuner. Detonation will not be an issue at all, I will have full controll of my timing and fuel curve.

[Drew Pojedinec]

Seems like a compromise engine.......

*cough* get a diesel *coughcough*

[ScotiaFE]

Seems like a compromise engine.......

*cough* get a diesel *coughcough*

High compression, deep breathing heads, small cam, low engine speed, high gear ratio.
Yup should run great.