So I've finally got the new 408 setup together. I've got it tuned and dyno'ed (425/445 SAE corrected). Now that these major milestones are completed, it's time to get technical. My goal was to just get it up and running (which wasn't easy judging my past problems). But now that I have, I want to absolutely critique my setup. I want to know all the good/bad/ugly about my combo (everything other than the shortblock internals as I'm not willing to be changing those other than the cam, also wanna keep the LT/ORY i just put on) that I'm running. I figured I put together a pretty decent setup but it can always be improved upon. My setup is the following:

HPE 408
11:1 SCR
244/248 635/627 112 (installed 4 degrees advanced for the restrictive heads)
Eagle crank
Callies rods
Diamond flat top pistons w/ 2cc reliefs
Stock 6.0 heads (already had em, didn't have money for others)
SVO 42 #'s
LS6 intake
P/P stock TB
Edelbrock 1 7/8 stepped LT's/ORY
LM catback (soon to be changed... to what i haven't decided)

My goals are to have a 550+hp daily driver (with a power band from ~2k - ~6800). This thing needs to be responsive at lower RPM's for all the driving around town that I do but I'll obviously sacrifice some low end due to the bigger cubes and the fact that I like the badass lope. I don't quite have the money for heads or a 90/90 setup yet. And before I even think about those, I'd like to figure out things like: what exact cam specs would be optimal for my goals? what heads would work best for me? would I be killing much hp if i went with high flow cats? etc. If you've got constructive criticism, I want it. I'd prefer to have the most technical answers possible, as well as the reasons behind them so that I may learn for the future. Obviously my major issue that I want to get nailed down is exact cam specs for my next cam (IF i even need one), and then go from there. Thanks guys, I appreciate it.

 

I don't know if it's right but I get an 11.04 dcr which seems really high for a street car. I assumed a .041 gasket which will decrease with a thicker gasket, but not by much. Heads would really be key in getting to that power level. I don't see it being easy with a 11.1 static ratio. How is the timing now with stock heads? Have you looked into a carb intake?

 

those are good numbers for stock 6.0 heads.to get any where near 550 rwhp your going to need a good set of heads,and probably a Fast 90/90 set up.that's your biggest restiction now with the extra cubes and that cam.i would save up for a set of AFR 225s,ETP 225s or a comparable stg. 3 head.

 

I dont know how you got that high of a dcr, I used THIS site and input the following:

Bore in Inches : 4.03
Stroke in Inches : 4
Rod Length in Inches : 6.125
Static Compression Ratio : 11(:1)
Inlet Valve Closes ABDC : 85.8(0 to 90 Degrees @ .050" Lift) it says .050", but it should read .006" or advertised duration
Boost Pressure in PSI : 0
Target Altitude : 0 (Feet)

the calculator then says that the DCR should be 7.20:1

I have a 383 with a cam very similar to yours duration-wise, and lobe lift-wise. Course you have more lift with your 1.7:1 rockers than my 1.6:1. My cam has a much narrower LSA and is installed straight up. This brings my IVC point a few degrees before yours. I don't have a very high c/r, at 10.7:1. this yields about 7.65:1 dcr for my engine. The car was a little sloppy on the low end but I had a 3500 rpm stall to eliminate some of that. at 50 mph with the converter locked the rpms were around 1800, I could roll onto the gas (just enough to keep the converter from locking) and it would pull smooth. I just had a mail order tune also. you have more cubes than I do but a later IVC. I'd imagine yours would be a little easier to drive. To me, my car was perfectly driveable every day. had plenty of low end power BUT again I had a high stall. I think your IVC is too late and your compression is too low. Of course you said your cam is advanced +4, so if you bring it back straight up that should bring the DCR to 7.53. the advanced to straight up should bring the IVC from 85.8 to 81.8 I BELIEVE, Im not 100% sure on that. you'll get some low end back and raise the DCR some. from there I'd fiddle around with the calc to figure out how what SCR you'll need to get a DCR of 8.5 which seems to be a pretty acceptable number.
with the IVC set at 81.8 (since the cam is installed straight up) I get:
SCR / DCR
11.5 / 7.85
12 / 8.18
12.25 / 8.34
12.5 / 8.5

I dunno if I would go 12.5. Im just throwing numbers out but im sure if you get someone to tune it really well it would run on pump gas at 12.5:1 assuming the DCR is 8.5. I would play it safe and try to get to 12.25ish.

after all that I'll use THIS static c/r calc to find out what a smaller chambered head would do.
I used:
bore: 4.03
stroke: 4
head gasket thickness: .051
deck height: 0 (I dont know what your deck height would be)
piston top volume: 2
combustion chamber: 71 ( think thats the stock 6.0L head c/r, correct me if im wrong)

That gives me a static c/r of 10.99. pretty close to your stated 11:1 a thinner .041 gasket gives me a 11.25 scr. 64 cc heads and the thinner gasket give me 12.21 scr. that 12.21 scr should yield, with your cam installed straight up and 81.8 IVC, a dcr of 8.31:1. that seems pretty good, no?

so...
-I would keep your cam but install it straight up.
-use the thinner head gasket.
-get good heads with about a 64cc combustion chamber. I'll leave the head selection up to you but personally I would go with dart 225s, they seem like a good head for someone on a tighter budget. down the road if I got the urge for more power I'd probably send them out to get CNC'd or hand ported. possibly bigger valves, I forget if they have valves for a 3.9" bore or a 4" bore.
-obviously a fast 90/90 setup since so many guys get good gains. maybe port match them to your heads?
-a good tune.
-have a blast!

of course I am NOT an engine builder, I just go by everything ive learned over the past few years. I would definitely listen to some of the well known guys here than me!

 

I have a brand new set of FFHP stage 3 6.0L heads that I'll let go cheap, man. PM if you are interested.

 

Your set-up isn't bad, you just need heads and intake. Your cam is fine. A set of ETP 225-240cc heads and a FAST 90mm intake should show you the gains you want. Nothing drastic, you just need the right parts.

 

Yea, I know my setup isn't bad at all, I just want to finely tune it for the goals stated. I am running the stock MLS 6.0 head gasket which I believe is around .052 compressed. I know a 90/90 is obviously necessary but wanted to make sure my cam was optimal for my street driveability needs.

Zigroid - the cam is advanced for my stock restrictive heads that are causing the power to peak at 5500, so i wanted to bring the power band down as much as possible. I'm not really concerned much with the DCR at this point. I know it could be higher but that's not a big concern at the moment.

 

Keeping the cam advanced will give you the highest DCR possible with your givin valve events.

 

hmm I guess I had it backwards then

 

Just got done with finals, my brain has nothing left

 

Advancing the cam closes the intake valve sooner. A earlier closing IVC raises DCR.

 

Can you please clarify if you want 550 rwhp? or flywheel? Either way, if you've been to the dyno section (think i've seen you there a bit) you know what heads you're gonna need to shell out the cash for.....rhymes with "hehe" (ETP 225's)!

 

550 to the wheels. Yea, I'm pretty sure with the way things are looking that i'll be going with ETP's. I've yet to find a better solution and I'm definitely not looking to sacrifice on heads. Of course... we all thought Patriot heads were badass at one point, so I'm going to keep my eyes open and for a while until my money tree grows back. I'm in no rush. I just want to do things once and do them right.

By the way, what's the difference between the 225's and 240's? I remember reading up about them but can't remember now. If I had to make a guess I think the 240's were for a larger bore (4.125)?

 

I think you can use both on the bore you have. (Don't hold me to it though.) The 240s have a slightly larger intake valve as well. 2.100" versus 2.080" according to their website.

 

little larger intake valve, we can set them up for the same bore size Jon. They pull away from the 225s around .400 lift and hang on a little later then the 225s. If your serious about trying to make 550 to the wheels, 240s is what we would put on it.

Look for around 11.3-11.6 area compression, back the cam up a bit and stick with what you have for the time being. See where it all falls out and then pick a new cam if need be based on how it responds to the current timing.

On the cats, the more overlap and cubes a motor has the worse an exhaust restriction such as that will affect it. Trying to make 550 to the wheels, I wouldnt even think about putting cats on it. After you hit your goal then think about that... but cam timing is going to be a good bit different for a restricted setup.

Another set of 225s are on their way here, then we should be getting some 240s and a set of 255s in the next month or so so you can see the results firsthand

 

Do you think 550 N/A to the wheels is achievable without getting really ridiculous with fine tuning?

 

Well theres only a handful of cars that have made that power streetably, VINCE etc, possible yes, but it takes alot of good parts (namely cylinder heads/cam)

 

Ok, doesn't sound challenging enough.... now I want to make 500 with stock heads