Excellent! We keep saying this on many threads. With only 2 degrees of overlap, people will ask "holy crap how big is that cam?" if you tell it idle at 650 and cut your idle timing back slightly

 

I strongly agree.

 

So would the Trick Flow GEN X 245 heads get me to 650 at the crank?
Super Chevy was able to get a 383ci LS with the GEN X 215's to 526hp on an engine dyno with dual quads with a .575 lift cam and only 9.6:1 compression
If I go with 245's, 11:1 compression, the same basic dual quads setup, a .600-625 lift cam, and 408ci will that get me fairly close?

 

Should be very close..... don't get caught up in lift numbers as they is not as important as duration numbers.. aim the compression on 11:5. The first post I made on this thread about the 408 build. It's really a 650 horse motor. That setup had room for improvement.

 

Those heads on a 408 with a good cam, yes, you can see 650. Good call going to 11:1 compression. That will allow you to tolerate more cam. You'll probably be in the BTR S3 or S4 range or the Titan 5 or one of tick's larger grinds like the polluter. Your torque curve will likely be a bit lacking (comparatively) down low. Larger cam will usually mean less torque, and larger intake runners will usually mean less torque. It's still a 408, so it will naturally make torque, so that's just compared with higher RPM numbers

If you're wanting a really good balance, the new Mamo 235 heads are worth a look. Those are in my 408 build plan along with a cam in the range of a titan 4. But then, i'm less interested in dyno numbers and more interested in how fun it is to drive. FWIW, on a dyno, I don't care about how high the numbers are, but how CLOSE they are.

 

with everything matching and optimized 625-650 fwhp should be attainable. a good head with a 235 cc or so runner and strong mid range lift numbers to keep velocity up will help with the torque. haven't seen any data for the dual carb setup but a ported super vic would be hard to beat if you have room to fit it under your hood. down side is as like already said,a carb intake loses out on bottom end/mid range torque compared to a tuned runner plastic intake so it is a tradeoff as usuall ,but at your weight you should be able to reach your 1/4 mile times.

 

Running a Mamo head and cam spec by him would be a killer!!
I'm go do this post over again so look at this combo carefully and you can see it has some horsepower hidden in the setup....
~408ci shortblock
~11:0.1 compression ( that can be raised)
~240/246 114 lsa 600 lift off the shelf cam ( bet Tony can cut a grind that would hit that sweet spot)
~ dum1-3/4-inch QTP headers (would gain power with bigger headers)
~ 42-pound FAST injectors and billet fuel rails
~ precision tuning supplied by a Holley Dominator EFI system
~AFR 245 heads out the box (not maxed out by hand porting/blending etc)
~LSXRT from FAST out the box ( that can be ported)
~ 626 hp at 6,500 rpm and 580 lb-ft at 5,400 rpm

#this combo was tested by Richard Holderner

 

That does look like a killer combo.
And like you said there's still more on the table for it with bigger headers and port mathcing and the like.
I will stay carbed I think, and I'm seriously going to check out the Holley dual quad setup. I know it was good for 50+ft-lbs under 3000rpm with two 390s over a Victor Jr with a single 750, with only 1hp less at peak.
EFI would be nice to have and all, but $900 for just the intake (no injectors, fuel rails, etc) vs $320 for the dual quad intake? I think I'll go thst route and put the money I save into some nice heads and valvetrain.

 

To make 550rwhp while still making a lot of low end torque is going to be pretty hard with a 408. That's about 650-660fwhp. You are going to need to find an engine builder to set everything up for you so it all works perfectly in conjunction with each other. You will also need all the other bolt ons like electric water pump, under drive pulley, high compression, etc. Talk to Pat G about making that kind of power and keeping it streetable. You aren't just going to pick and choose parts off the shelf and make 550rwhp. And even harder when running a ford 9" rearend. Can I just ask why you are so set on making 550rwhp? I don't understand why people get so stuck on peak numbers or why they decide that this is the number I want to make. Pick a reasonable range for your hp goals and then build it. I can assure you that you will not be able to tell the difference between 500rwhp and 550rwhp. From most of the builds I have seen it seems that 500-525rwhp is what most people make with 408ci stroker engines. The guys that are making more have given up drivability, low end power or spent a lot of money to make that extra 25rwhp that you will never notice in a street car. And a car that makes more power and torque under the curve and less peak hp will be way faster and way more fun in a street car than any that makes just huge peak hp numbers at the sacrifice of lowend power or power under the curve.

 

Well the reason I was shooting for those numbers was because my car (71 Nova) used to have a 383 on nitrous that had about 600hp (estimated crank, possibly had more based off the specs) and ran a consistent 7.2 in the 1/8th mile, which is about a mid-high 10 in the 1/4. The chassis is the same now, except it has a carbed 350 with stock heads that only has about 300hp (again estimated crank, and that's being a little generous).
I'd like to make the car back into a mid-high 10 second 1/4 runner, but the majority will be 1/8th mile, autocross, and street driving, so I would like to get all the low end I can.
I'm picking heads, intake, cam, exhaust setup, etc to try and shoot for that low end as much as I can (long tubes, 235-245cc max heads, mid rise dual plane dual quad intake, hot street -oriented but still racy cam) and then I'm hoping I can dial in enough compression and tuning along with matching the cam and heads and such to get me where I would like to be. I've talked to the engine builders at my work and they have said it is possible, but like you said it won't be easy and it'll just take some thinking for matching everything together. I've got a long while before this build will take place and I'm going to use that to do as much research as I can and align the best possible options.

 

I the same basic setup and I got 420 on dynamics however these numbers are fine because u are running at low pressure

 

Chris Frank did 693 @ the flywheel with a set of his FRH Stage 1 Ported LS3s, FAST Intake, and a 244/250 110+4 Hydraulic Cam... and it peaked at 6900 with a FAST. All in a 408.

Just do that. It's $1400 for the heads + core. Get him to spec that same cam and the other components (pushrods/lifters/etc).

That's 620 to the ground. Or get him to spec out a Cam Motion Low Lash Solid Roller for it...

On here, a guy took the FRH Stage 1 LS3s, an LLSR 236/246 Cam, and an LS3 intake and made 550/505 in a 376 and it peaked at 6900 as well. You could just run that combo on the 408 and it'd make probably similar HP but another 25-30ft/lbs of torque. And it wouldn't peak quite as high. But it would drive very nice.

 

Holy hell o.O
I just might have to hit that up haha, but I was leaning heavily toward cathedral ports, might just take the hit on the power if they can be set up in a similar way. That's crazy

 

He has reworked his head. This is what happens as technolgy continues to march forward. The LS3 heads have been out long enough now that folks are starting to really exploit their capabilities. We were comparing LS3 heads 3-4 years ago against aftermarket cathedral ports that had 15+ years to mature. And the cathedrals were better.

But now, some of these LS3s are monsters. I mean, the Stage 1s flow 390cfm from a 269cc port. That's as efficient as the big aftermarket cathedrals and even moreso than some of the medium bore LS7s.

 

How are they on the low end though?

 

I'd say good enough. At 3500 does a cathedral beat them? Well. Not always. You can use a lot less cam with a rectangle port head, which is where most of the losses come from. Does a Cathedral perform inherently better there? Sure. But on some of the newer LS3 heads like from TFS or FRH, the low-lift flow numbers are so insane, they make up for port inefficiency with just brute flow.

Take some time to look at LS3 combos or heads/cam LS3 combos. Those guys are making 500+rwhp with smallish cams and a lot of torque 460+ with usually stock heads or heads with just worked exhaust ports on a 376.

 

Jake your posts on this topic are starting to echo Martin. "I cringe when I hear people say rectangle ports don't make torque". Martin had a very good post about this in his LSA doesn't matter thread.

 

Well, there's enough real world evidence now to show that people have figured out how to cam them to make power everywhere. In the early years of the LS3, they weren't doing that. But by 2010, by and large, people knew what worked and what didn't and optimized the valve events. Now a lot of people are really modding the LS3 and experimenting more. That really came as warranties ran out on the Vettes and Camaros and a lot more dudes starting modding. For a long time, I only considered Cathedrals. They are proven. They are mature. And there are tons of data on what works best. But there are potentially better alternatives if you're willing to look.

When you combine more effective port options now, you end up with something that's hard to ignore.

 

See now that makes sense. There would be an inherent 3-5 year delay due to warranties before people started chasing power. Never thought about that