finally got around to it today. was done at norris motorsports.

review of setup
408
11.5:1 compression
SLP lid
vinci ported MAF ends
NX 85mm TB
NX intake
42# SVO injectors
2.02/1.60 ported 4.8L heads
232/240 .551/.551 (1.7 ratio) 117 LSA
crane 1.8 shaft rockers brings lift to .589/.589
dynatech 1 3/4 stepped 1 7/8 headers w/3" collectors
bassani tru-duals 2.5" w/x-pipe
yank py3400 converter
3.73 gears
275/50-15 nitto DRs
250 NX NXL DP nitrous

this run was on motor converter unlocked



this run was on motor, converter locked 21* timing



same run with 26* timing



this run is with the 250 shot. tires spun on the dyno and didn't hook until almost 5500 rpms



here's the same run using mph, so you can get a little better view of the run

 

Definitely the wrong heads/cam for an NA setup. Retarding that tiny camshaft would help immensely.

Don't take it the wrong way, but you're giving up ALOT of NA power... Even $999 Patriot LS6 heads and a more aggressive cam would have made an additional 40+ rwhp on motor while making no difference on driveability or power on nitrous. Whoever designed that setup didn't do their homework.



Mike

 

Agreed.

Unlocked numbers or not... your peak flow numbers are at way higher lift and the heads arent the best.

may I suggest livernois, they are on sale too

 

i don't mind having a discussion about it, so here goes....

yeah, me and vinci high performance didn't do our homework at all. just figured we would throw something in there. do you know the flow specs on my heads?


let's compare the patriot heads:

patriot LS6 style heads 2.02/1.57 3.905 bore flow
mine 2.02/1.60 3.905 bore flow

lift -------- p i/e ----------- m i/e
.100 ------ 72/65 ---------- n/a
.200 ------ 140/124 ------- 145/109
.300 ------ 202/160 ------- 209/148
.400 ------ 244/196 ------- 253/174
.500 ------ 280/220 ------- 288/181
.600 ------ 304/229 ------- 301/205

my heads beat their comparable heads on the intake side. so, what would another 25-30 cfm on the exhaust side do for me?


patriot LS6 style heads 2.08/1.60 4.125 bore flow
mine 2.02/1.60 3.905 bore flow

lift -------- p i/e ----------- m i/e
.100 ------ 78/66 ---------- n/a
.200 ------ 147/124 ------- 145/109
.300 ------ 209/164 ------- 209/148
.400 ------ 255/206 ------- 253/174
.500 ------ 296/229 ------- 288/181
.600 ------ 322/237 ------- 301/205

looking at their stage III with a much larger intake valve isn't much better on the intake side again. again, what would another 25-30 cfm on the exhaust side do for me? and these patriot heads were flowed with a much larger bore size. at this point, i can't see spending $1000 for only a better exhaust port flow side.

now onto the cam. i've seen smaller cams than mine make more power. so, tiny cam it isn't. i could probably get more torque out of it by bringing the LSA in tighter, no debate there. driveability is in the eye of the owner of the car.

 

might want to review my above post about my head flow. peak flow numbers don't make a head better than another. also, remember the cam lift is with 1.7 rockers. add the 1.8 ratio and it comes to .589. i'll edit my initial post to clarify that.

 

Flow numbers are only part of the equation.

You're contradicting yourself. First you say that your heads "beat" Patriot's because of the flow numbers, then in the next post, you say that flow numbers aren't everything. So, which is it?

Regardless, I've never seen 4.8L or 5.3L heads make impressive power on a stroker motor and your car is proof. Add a tiny cam that belongs in a stock-cube motor and you have a recipe for mediocrity.

BTW, I had some Patriot Stage II 2.02/1.60 LS6 heads (that your 4.8L supposedly beat) and a 238/240 110LSA -4 in my car that put down 530/505 with a 408..... roughly 90 more rwhp than your locked converter car. Not all flow benches are the same. Yours might flow 300 on their advertised flow bench and when you put it on another, it might only flow a true 270.

Darts are pretty consistant -- advertised at 300ish cfm max and actually were flowed at Meaux's in the mid 290s.. I guess that's why my heads/cam car put down 471/416.

Anyway...like I said before:
The heads/cam/intake manifold in your 408 is choking it pretty badly. Take it for what it's worth...If you intend on spraying it into the 650+RWHP range, then have fun with it.

Cheers.

 

read a little closer. i said peak flow numbers don't make a head better than another. that was in response to his statement about peak numbers.

once ported, what does it matter if they were originally 5.3 or 5.7 heads?

again i said my heads 'beat' on the intake side. your telling me to spend $1000 for heads that only flow better on the exhaust side. so, i'll ask again, what will another 25-30 cfm on the exhaust side do for me?

as far as your 90 rwhp more goes, let's see, more intake duration (6* and you call my cam tiny), 7* less LSA which gives you a larger mid range boost over mine (way more overlap than my cam has), retarded 4* for more upper rpm power (mine is ground advanced 5*), 6 speed trans versus auto with 3400 stall, and don't know your rear gear.

now it's heads/cam/intake manifold. your first post only said heads/cam. why is the NX intake a restriction? any flow numbers comparing it to other manifolds to support your claim if it being a restriction now?

i appreciate the conversation. do you have the graph of your 408 motor up somewhere? i'd like to take a look at it.

 

you already had the heads and cam right?

was that your reason for not going bigger....at least the cam. with the expense of heads i can understand that.

but i would think you could have picked up a bigger cam for cheap used someplace. and made alot more power.

just curious as to why you started off with such a small cam...on a big motor?

 

I hate to say this because nobody likes criticism, but I agree that you're leaving some HP on the table. That cam is really on the small side for a 408 and I think you'd be surprised at how well a mid-245 cam can drive when tuned properly. I don't know what kind of work was put into the 4.8 heads, but flow numbers aren't the only thing to look at. Mike is a really good guy to work with, so don't be afraid to get his opinion. The bottom line is: Are YOU happy? If so, anything else is purely academic...
FWIW, I know you can't compare a M6 to a A4 on the dyno, but my little/low-budget/LS6 intake chokin'/not all bolt-on havin'/old-school Hooker header wearin'/Y-pide saddled/5.3 headed 383 makes better N/A numbers and about the same nitrous numbers (more torque, tho) on a TNT wet 150 shot. Not saying this to be a d*ck, just to give you some background on why I think your numbers are off. Best of luck to you!

 

Don't miss the killer nitrous system he has. He built this motor to spray......

 

LS6 heads are a COMPLETELY different animal than LS1 heads. Properly ported and setup LS6 heads can support upwards of 650-700 horsepower with no problem while getting the intake runners around 240cc+. In fact, a few LSx records were set with these heads including Futral's 9.9x@137 stock-cubed 6-speed run.

When you lock-up the converter on a dyno run you're taking out the "autos make around 5% less horsepower to the wheels than a 6-speed car" standard. Locked-up you're making 440rwhp. I made 530rwhp, but it's actually a little bit more than that since I did it through a Vette IRS. Basically when you compare my Vette IRS 6-speed to your locked-converter auto with a solid-rear, it's the same thing.

FAST 90/90s make the biggest power. That's why every big-power setup uses them (or a $2000 sheetmetal intake).

Looking at your dynograph on motor on the 26* locked up chart where you made 440:
You're severely undercammed. You're peaking at around 5500-5750 and start dropping there. Your car should be peaking at around 6000 rpm at the least and holding it for a few hundred RPM. Your cam isn't setup correctly at ALL for this motor and the graph shows it. 232/240 and 5* advanced on a 408? Why are you making the cam act SMALLER by running it advanced?! You should retard it at the very least (actually you should step up the cam size). 117 LSA?! You aren't running a turbo or a blower. There's just no need for it on a NA or "nitrous" motor.

My $.02

My dynochart before and after Futral's tune.

 

heads were from the wife's motor. cam is new.

how can my cam be small, when kraest's cam is right along the same duration?
238/240 110LSA -4 - he has 6* more intake, same exhaust, 7* less LSA and retard 4*.

not saying that i didn't leave some power on the table with the 117LSA. i knew that was coming. there's a definition of driveability that means different things to everyone. and tuning for another.

 

if i didn't want criticizm, i would not have posted up. i'm all about discussions.

again with the small cam. how is it small, when kraest's cam is 238/240 and mine is 232/240???? i've seen a 402 in a GTO make 450 rwhp with a 224/224 cam.

my nitrous torque numbers aren't accurate for a peak number. as i stated, the tires spun on the dyno until about 5500 rpms when the dynojet started reading. you can see it on the dyno sheet. that will explain why you have a higher torque peak number than me with your 383.

am i happy with it? for having 663 rwhp, sure. not too many everyday driving, full weight carrying cars are out there.

 

what makes it the cam's fault? why not another valvetrain issue? no doubt i should be peaking higher, but what's stopping it? the 5* advanced is ground into the cam. i zero'ed the cam. that's the way vinci does their cams. is that the reason why? there's another person with this same exact cam in a larger cube motor in a vette. i'm trying to get ahold of his graph and see how his did.

i might try retarding the cam. it'll only take about 1.5 hours to do it. i have an adjustable timing chain. all it's going to do is just move the rpm band up.

heads? who knows for sure without trying. i still don't see what 25-30 cfm on the exhaust side will do for me.

 

When you say "zeroed", do you mean you installed it straight up or 5 degrees retarded to get it to zero? If you installed it straight up, then it's 5 degrees advanced and will kill horsepower on a large cube motor because you're making the cam act smaller than what it is -- I guarantee you find much more power retarding the cam until it isn't advanced at all (retarding it 5 degrees) (or getting a new cam altogether )

Once again, you're talking about peak numbers, which don't mean anything -- flow numbers can differ 30-40cfm from bench to bench and honestly you can make flow numbers say anything you want. Regardless, those heads aren't moving enough air and the cam is too small -- and it's shown on your dynograph. A low peak and not carrying the rpm like that shows restriction in the setup.

Mike