Is that an accurate calculator?
Remember when I went from 1 3/4 to 1 7/8 I gained nothing.
I think 2 inches might be overkill.

 

My LS3 heads are ported.

 

700 hp is so easy......i could **** it out. 800 too. Nothing more than 402 to 418ci needed before 8k...wink,wink...

 

It's based on your EVO, peak HP rpm, displacement, etc. On your older cam (like in the OP), it says 1.8 is optimal, which is right between 1-3/4 and 1-7/8. So, on your old cam, 2" would have actually lost vs 1-7/8.

Edit -- if you figure 6300 rpm for peak power instead of 6900, it shows 1-7/8 is perfect. So alot depends on what RPM you really want to be making the engine works its best.

Likely the same sort of thing here. If you swapped from 1-7/8 to 2, you see minimal gains. But it's more just what's perfect vs less than perfect. make sense? Same calculator says I should be running 2-1/8 headers, but F body, so I won't be going any bigger than 2"

 

stepped header......is Best!

 

Makes sense Darth.
It is an interesting thing to know though.
One other thing do you know if heavier rockers actually lose hp?
I know looser stall converters do.

 

Heavy valves.....and springs,retainers,locks etc.....Rocker is just a leverage arm. As long as u can keep the rocker stable it doesnt care. Pushrods are doing all the work.

 

I made an edit while you were typing. If you change peak HP RPM to 6300 vs 6900, it brings the ideal size back to 1-7/8, so it depends on what RPM you honestly want to make the engine its most effective.

Heavier valvetrain stuff does affect power, but differently than you might think. Heavier rockers require heavier springs, and that compresses the lifters more, needs heavier pushrods, etc, all of which can show up as internal resistance. Solid lifters mitigate a lot of the penalty from increased weight, because they don't compress. A nice stiff pushrod then completes the package, and you'll make great power.

On a couple of motors I'm personally familiar with, owner(s) went for the lightest possible valvetrain and kept the cam small. psi1511 springs, titanium retainers and keepers, stock rockers. Between the springs and hardware, he cut almost a pound and a half out of the valvetrain. Couple that with the light sodium valves from a corvette 243 head, and you have a great formula. As to power, it didn't show up much on the dyno. But driving it, that thing revved almost instantly. It was very very responsive and it felt very fast. When I drove one of them, I hit the limiter on accident. It just got there so quickly and I wasn't ready for it to get there.

I think a good analogy is a light clutch. you might show 10hp from a light clutch vs a heavy clutch. But driving the car accelerates far quicker than the 10 hp gain would imply. Lighter valvetrain parts are the same way. You free up the motor to rev, but you may or may not see it on a loaded engine dyno.

Now, that's not going to work for these larger cams with .700 lift and 250's duration. you need a roller rocker and longer valves, so you're adding weight to the valvetrain. The 1511 spring doesn't have the travel, and you really don't want stock rockers much above .600 lift. Now, on my stock headed ls7, I cheated a bit running the stock rockers up to .653 lift, but I had lash caps on it to allow for more "scrubbing" on the valve tip. Just more surface area in general. But when you get into the bigger cams and higher lifts game, you necessarily make things heavier so they can be stronger. In which case, you need enough spring to control all the mass and then make sure the spring is the weakest link in the valvetrain, so it's the only thing that gives under load. you'll gain more from the bigger cam and higher lift than you'll lose from the added valvetrain weight.

Hope that all makes sense. very jumbled train of thought for which I apologize.

 

Another thing learned as of late .......with what i got i was kinda upset with compression. But thought about @ 12.2 compression on pump gas 93 octane has a Smaller timing window = less power that can be made vs 11.5 comp which would make better hp. Add e85 and the windows open again..was thinking of just staying pump gas

 

That's right smoke.
I'm at 12:1.1 on E85 and we managed to get in 25 degrees of timing.
But as stated more work needs to be done on tune.
Oil pressure needs to be sorted first

 

Very good explanation Darth.
Remember when I said I test drove engine with the hydraulic 242/257 cam?
I was very surprised how responsive the engine was to throttle input the speed and which it revved.
Way more responsive than before.
Could have because of those high rpm lifters too.
I only drove it in the low to mid range rpm band though.
I'm expecting with the solid roller it should be even more responsive and maybe have a faster acceleration rate.

 

You damn right Solid Roller 4 the win....get the oil pressure correct with a good tune and enjoy. On the tune can't you get someone in the States to send you a great basline tune. Process of elimination...being the tuner in ?

 

https://ls1tech.com/forums/dynamomet...-601-rwhp.html

I ask....what's the big difference. I read alot....on cheap factory blocks storkers and hp

 

707hp on a 6.0l 403ci.
Yet none of these NA builds can do it?!?! Sure luv to know how Mast stays in business.
https://www.mastmotorsports.com/coll...te-efi-engines

 

+1 on this last paragraph...


What do you guys feel is a universal hp difference on llsr vs. hydraulic like some of these mail order 700hp NA motors? Im curious for my own knowledge.

 

I've come 1 conclusion this dude is SAF...
Mast sell warranty based HYD roller turn key engines, no hassle maintenance free ... SR cam swap slight mill for a bump *if needed or wanted....theres your 700+
Mast Ls3 heads are better than Dart 15 degree heads or Factory ported Ls3's and we all know what was seen.
700+.......

Martin Smallwood said it's around a 25 to 30 hp difference

 

On the everday 700....700 is to be pissed on now. Not a bad thing we've just past this mile marker up.. Some just don't know it. 800 is the in thing now NA & streetable.
How many 700 + threads with a factory block stroker is wanted...got around 10 without even looking...All bookmarks.
Minus the 2 listed...the 427 ls3 block & heads stroker 740 11.5 compression a SR. Diet Cokes stroker Ls3 i can go On & own .....Tim's 416 before the resleeve 454.....
Nothing new under the sun....all builds were before Speed except for Flyin....

Hell the thread with the 601 rwhp has 700 in it...Erik of HPR said 640rwhp with small changes

 

Itd be nice to know more details of all of those builds being compared...Wasn't Dietcokes build a 15:1 ethanol motor IIRC? Or so I thought I read somewhere.
Stating just the highlights is vague and rarely apples to apples. Im prolly just mad af bcuz NJ doesn't have any e85 readily available. Guess no matter what hp my build ends up making, It ll still be BS build to some because its not max effort.

 

You really don't need hi comp for 700 or 800 but it helps make it that much easier....250 @ .050 is the baseline for 700
260+ for 800 if all the small stuff isn't overlooked.. Compression helps. General bases for a factory block stroker....

Your correct on Diet Coke...but he didn't do anything other than build it for corn.... Dome top. Flyin made 800+ with 13.2 ish. Made 800 from 7800 to the peak @ 8200. Shorten the cam by maybe 4 degrees would lower peak rpm and still get 800 maybe at 7800.

Impress self and set a realist goal. Find a goal and find builds just like it....copy and add updated modern parts with your own ...Rick Flair...Wooo! Rkupon me ask 4 800 isn't a fairy tale under 8k. Use reference builds with similar size.. From: research. You know what to expect.

 

I read the first page. And he still has bricks after the headers. It's not going to breathe like that and I'd be surprised if they're not restricting the current setup. Unless they go, upping the header size won't gain, imo.