Let's talk LSA

[frnkeore]

314 in / 223 ex @ .600

[blykins]

Based on some of my SBF stuff that I’ve done, I’d be in the low 250’s at .050”.  I’d also split the durations by 10 deg.  That’s just a rough ballpark, I’d have to look at advertised durations and some other numbers.

[frnkeore]

 The camshaft was 254/260* @ .050, 104 LSA, installed at 101*, and made 561 tq @ 3800, 595 hp @ 6200

The above is Joe's results, with a 375 CI engine, for what you suggest.

[blykins]

The camshaft was 254/260* @ .050, 104 LSA, installed at 101*, and made 561 tq @ 3800, 595 hp @ 6200

The above is Joe's results, with a 375 CI engine, for what you suggest.

So you think the same cam would make the exact same peak in an engine that’s 70 cubic inches smaller? 

[frnkeore]

No but, I don't think there will be 1800 rpm difference, either.

Let's look at it this way, my 8000 rpm air requirement is 712 cfm. The 375 @ 6200 is only 673 cfm.

Point taken though and I'll down grade to 260/266.

[blykins]

No but, I don't think there will be 1800 rpm difference, either.

Let's look at it this way, my 8000 rpm air requirement is 712 cfm. The 375 @ 6200 is only 673 cfm.

Point taken though and I'll down grade to 260/266.

There will be 1800 rpm and then some. 

You can do whatever you want, but it's a humongous difference in cam specs between 70 cubic inches.   Displacement and head flow are the two biggest components of what cam specs are needed.   The cam's job is to open the valves to fill the cylinders.  If the cylinder volume is much smaller, then the valves don't need to be open as long.   Same with the cylinder heads, if they flow well, they can pack it in, in a smaller amount of time. 

FWIW, I did a 351C, stock stroke, that peaked at 8000 with a camshaft with around 258° @ .050".  The factory 4V heads with no port work and just the correct valve job flowed 312 cfm at lift. 

You have about 50 less cubes.

I have a ton of dyno results for small block road/drag race engines, from 292 cubic inches to 460, from ported factory 289 heads to 400 cfm CHI 3V heads.   They all needed extremely different camshafts.  One size doesn't fit all and you can't just arbitrarily pick durations and splits without taking into account the advertised durations, which LSA's you're going with, etc.  I will tell you though, that with the head flow numbers you gave me, a 6° split will not be optimal by any means. 

I would also kick your cfm calculations to the curb and let the engine dictate which carb you need.  It won't be a 1200 cfm Dominator.

[Joe-JDC]

Don't use my Y Block for anything more than an example of what I had to do to make the engine work in the rpm band EMC chose.  That same 375 Y block now has a 268/274* @ .050" on a 110 LCA with a .403" lobe for 1.7 rocker arms, shooting for 625 hp NA.  I dyno'ed it with a 1250 Dominator, and with a tunnel ram with several combinations, ultimately two 850 cfm Pro System carbs.  What I would be asking myself, if I were looking at your parts, is:  How much horsepower do I want to make, and what camshaft do I need to get me there?  Whenever you set a rpm as a goal, you create a whole lot of expectations of what is needed, but in reality can only be achieved with a whole lot of money.  RPM needs lightweight parts, and the best of everything, and the best machine work.  That costs in today's economy. My engine blocks are 58 years old, and the heads are 61 years old on the 303Y.  I do this because I like to take the underdog and try to make it a winner.   Joe-JDC

[frnkeore]

A overview of the intake tract. It will include a 850 on a Victor Jr, Tunnel ram that includes pairs of 550, 600 and 650 Holley's. I'll also try to find a Hilborn type (lawn sprinkler type) FI. I do have experience with that type FI, as I used it on my Formula Atlantic, for a short time and when dynoed, it produced the exact same HP/Torque as my Weber's but, at the expensive of a lot more plumbing, so, I removed it. Because of it's performance, in that test, I think that it will have excellent tunability in this range, especially with the trumpets.

Based on every ones help,I've settled on the Howard cam spec at 257/263 .640 lift, 104 LSA, ICL 101 or 102. That will be my base, reference point.

If the max HP, exceeds 8600, I'll cut back on timing. Then change only LSA and see what the result is.

Again, I'm not looking for highest peak HP, I'm looking for highest average torque, in the last 2000 rpm, of the usable power band and how LSA will effect it. I should have, at least 3 examples, in the next 12 months.

Can I assume, from the response, that no one has tested, changing only the LSA, in tuning a engine?

[My427stang]

A overview of the intake tract. It will include a 850 on a Victor Jr, Tunnel ram that includes pairs of 550, 600 and 650 Holley's. I'll also try to find a Hilborn type (lawn sprinkler type) FI. I do have experience with that type FI, as I used it on my Formula Atlantic, for a short time and when dynoed, it produced the exact same HP/Torque as my Weber's but, at the expensive of a lot more plumbing, so, I removed it. Because of it's performance, in that test, I think that it will have excellent tunability in this range, especially with the trumpets.

Based on every ones help,I've settled on the Howard cam spec at 257/263 .640 lift, 104 LSA, ICL 101 or 102. That will be my base, reference point.

If the max HP, exceeds 8600, I'll cut back on timing. Then change only LSA and see what the result is.

Again, I'm not looking for highest peak HP, I'm looking for highest average torque, in the last 2000 rpm, of the usable power band and how LSA will effect it. I should have, at least 3 examples, in the next 12 months.

Can I assume, from the response, that no one has tested, changing only the LSA, in tuning a engine?

I would not assume that Frank, plenty of testing referenced here, it just seems to be not scratching your itch.

I personally have lost track of the entire configuration you are asking about, specific heads, exact compression, all cam specs, etc. I assume you are building for the aluminum heads and just going to play with the iron?   I think header and collector design will have to be taken into account if you want the benefit of the high overlap (however, I think you should be posting planned advertised duration too, to allow us to help) .050 duration isn't great for assessing overlap

Finally, I am not sure the early ICL is a benefit for you unless somehow you are limited on compression, would be interested in those numbers too. 

[blykins]

Can I assume, from the response, that no one has tested, changing only the LSA, in tuning a engine?

Sure have.  On multiple engine families. 

If I were you, I'd be focusing real hard on advertised durations. 

[frnkeore]

First, I didn't start this thread for my particular build but, to research how to maximize average torque at the upper end of usable rpm, discounting any effect of what it might do to the low end. I put it in the Non-FE section, hoping for broad input.

The reason for my build, is that last summer I came up with a virgin C80E block and 3 weeks ago, I got a good deal on a new, internally balanced 4340, forged crank. I already had both sets of heads and the rod/piston combo. I'm building the 289 heads, myself and will match the springs to the cam. The alum heads are complete so, I have to make sure the springs will work with the cam. I chose the lower lift range on the cam, to mitigate spring problems. If everything works out and I have enough spring and valve clearance, I'll go to 1.7 shaft rockers.

This is the cam spec, I will use:

Howard Standard Ramp Mech Roller
Cam #      .006   .020   .050   .200   Max Lift    Lash   Total lift 1.6               1.7

BR257400   298    289    257    174    0.400      0.022    .640 - lash .618    .658 net
-------------------------------------------------------------------------------------------------------
BR263400   304    295    263    179    0.400      0.022    .640

"Sure have.  On multiple engine families."

Brent, it's your proprietary property and to do as you please with it but, that was my original question. What does only changing the LSA, do to the torque/hp curve and dyno results would show that.  That is what I was asking for. Nothing else.

Regarding the headers, they will be boat or F5000 style headers, for my application. Primary length and collector style, to be determined. At this time, I think I want them tuned for 7000 rpm, the range that I want to pick up the most torque.

Since we are talking about my build, I do have a question. What size should the primary be and assuming I need a step, how should the step be configured?

 

[blykins]

First, I didn't start this thread for my particular build but, to research how to maximize average torque at the upper end of usable rpm, discounting any effect of what it might do to the low end. I put it in the Non-FE section, hoping for broad input.

The reason for my build, is that last summer I came up with a virgin C80E block and 3 weeks ago, I got a good deal on a new, internally balanced 4340, forged crank. I already had both sets of heads and the rod/piston combo. I'm building the 289 heads, myself and will match the springs to the cam. The alum heads are complete so, I have to make sure the springs will work with the cam. I chose the lower lift range on the cam, to mitigate spring problems. If everything works out and I have enough spring and valve clearance, I'll go to 1.7 shaft rockers.

This is the cam spec, I will use:

Howard Standard Ramp Mech Roller
Cam #      .006   .020   .050   .200   Max Lift    Lash   Total lift 1.6               1.7

BR257400   298    289    257    174    0.400      0.022    .640 - lash .618    .658 net
-------------------------------------------------------------------------------------------------------
BR263400   304    295    263    179    0.400      0.022    .640

"Sure have.  On multiple engine families."

Brent, it's your proprietary property and to do as you please with it but, that was my original question. What does only changing the LSA, do to the torque/hp curve and dyno results would show that.  That is what I was asking for. Nothing else.

Regarding the headers, they will be boat or F5000 style headers, for my application. Primary length and collector style, to be determined. At this time, I think I want them tuned for 7000 rpm, the range that I want to pick up the most torque.

Since we are talking about my build, I do have a question. What size should the primary be and assuming I need a step, how should the step be configured?

First of all, Merry Christmas.

Second, I can’t answer your question, nor can really anyone here.  I can’t count how many times I’ve said in this thread alone that it varies from application to application and you can’t make a general statement about what varying the LSA will do.......because it’s varying the amount of overlap!  It just depends.   I’ve seen tighter LSAs make more torque and I’ve seen them make less in comparison. 

With a 32 deg major intensity on those lobes, you’re gonna need a lot of spring pressure for 8000+ rpm.  Shaft rockers will be a blessing along with the newest valve spring sizes and technology, unless you’re running titanium valves.  At 8000 rpm, things start getting real serious.

Lastly, you’re setting at 84 degrees overlap at 104 LSA.  I personally wouldn’t run it at a 104 with that small of an engine.  As several of us have pointed out, there’s a point where you push more power out the exhaust valve than you translate into crankshaft rotation. 

I think I’ve reached the point of where I can be of any help, so I’ll bow out.

[Rory428]

Although I can`t really offer much input on the LCA question, I do have to ask what do you plan to do with this engine ? I have a 331 SB Ford in my drag car, it only dynoed at 482 HP, and I run nowhere near the RPM you are planning (pump gas flat top piston with a much smaller solid flat tappet cam than you are looking at), but it has gone a best of 10.15ET@129.9 MPH in my 2800 pound 4 speed car. I normally shift at 6600 RPM, and on a good pass with hit a little over 7000 across the finish line. That said, despite my much lower RPM use, I have had one factory 302 block split thru the main webbing. You seem to be expecting an awful lot of a factory Ford 302 block. I am currently running another stock 302 block, but now with a main bearing girdle, and so far so good. But if I ever decided I wanted to make any more power than it currently has, an aftermarket block would be the first thing on my list.

[frnkeore]

Thank you, very much Joe, for sharing that.

To be a little more specific, my goal is peak HP at a minimum of 7600 rpm, with 1200 cfm of carb (I may also try a Victor Jr & 850 carb) in a ~1350 lb car. I have a old Formula Car that I will cut off back of the roll bar and add the engine, C4 (if it will take it) and 9" gears, as a unit. It will be a drag racer. That, after the dyno work is done.

Brent, you'll note that I will not use the 289 heads, in the end result but, I will heavily modify the exhaust ports. I have them and will try them, to see how they compare with the 2.05 x 1.6 heads. I don't expect them to get very close to the aluminum heads BUT, they did run at that rpm level, in the 60's and 70's in Trans am, Shelby Cobra's and Can Am. Off the subject but, Gurney ran his 3V Westlake heads at Indy and placed 2nd, one year. I loved what Gurney did with the SBF.

Rory,
This will be the car configuration.

This 302 block was a real find. Based on a allen wrench measurement, the cylinder walls are 1/32 thicker than a 80's block that I have and I will use a girdle on it.

If your at all familiar with the F5000 engines, of the 70's, they ran 302's at 8k and 480+ hp. If not, take a look at this video.

https://www.youtube.com/watch?v=AR-1qO2i3Nw

The Aussy's still run them. The car in my avatar is a Formula Atlantic. SCCA grouped the F5000 and my class, together, in club races. I started my road racing, at the same time Danny Ongias did, at Willow Springs and Riverside, CA. My type cars where 1000 lb and 200 hp vs 1350+lb and 480+ hp. Top speeds where 150 vs 180 mph (Riverside) but, the Atlantic's corner better than F5000. Traco and Al Barts where the prominent engine builders for the F5000's, in those days. Barts even did a few 180 crank engines.

This engine will have very limited running, in comparison to the above described, just a few seconds at the drags and dyno time but, I know it will be highly stressed, in those short runs. I had been looking for a 3.25 forged crank, when this one fell into my hands. It could still happen.

Yours sounds like a very healthy 331. Is it in a Falcon or Mustang, or what?

[gt350hr]

   Frank,
      You've been schooled by some pretty smart guys. Though I am 8 years younger than you I would like to help you a bit from my 53 years experience with building and racing 8.2 deck Ford engines.
    First IF you had two ( or 5) 289 cams ground the same except for "ground in LSA" being two degrees different on each , you would see the "power band" would be lower across the board with the tighter LSA and it "might" have a small effect on maximum RPM. Again "20* valve angle , wedge" head. No Tunnel port , Boss , Gurney , TFS twisted , etc. No FE , Lima , 351C etc. NO generalities , SBC BBC MOPAR, JUST  289-302 SPECIFIC. EVERY engine has it's own peculularities.
   Second dump the idea of the 289 HiPo heads because they will not flow enough air , I don't care WHO ported them or how much. You're looking at 240 on a good day. GO with the aluminum heads as air flow has always been the limiting factor in the small block Ford.
   Third, You NEED compression. Yes I remember the late great Doug Nash(rip) telling me I needed to run flat top pistons for flame travel , and that is true for factory iron heads. BUT "modern heads" have altered spark plug placement and THRIVE on additional compression.
    Fourth , Buy an 8" 5,500 stall torque convertor because you will need ALL you can get to make your car move. You will also need a 4.86 (or so) gear ratio and a 28"tall slick to go 130ish mph . Use a 36" long 1-3/4" primary tube length "boat header" with an 18" long collector. Use the Vic Jr intake and an 850 DP of your choice.
     The stuff that was done back then doesn't work in today's world .I prove this to myself every time I go to the track with my old school dual quad intake and carbs instead of the Vic Jr I know will go two tenths quicker but doesn't look as cool.
   Randy