CuNfUzEd

iTrader: (14)

Hey guys. Here's my problem. I have a 02 SS That is only laying down 455 rwhp and 476 rwtq on a 408 all motor. Here is what she has.

408 CI Stroker (11:1 comp)
236/242 .598/.610 114+4 cam
Patriot Stage 3 LS6 style heads 63 cc 6.0
38# injectors
Hooker Longtube Headers
Custom dumped true duals w/ XR-1s
Shaner S3 Throttlebody
SLP Lid
Lakewood LCAs
B & M Ripper Shifter
Spec Stage 4
TNT Power Ring jetted for a 200 shot
Here some heads that I am looking at are MMS stage 2 5.3's ported and polished that will bump my compresion up 12.4.1. Would these increase my performance?

New heads
Lift CFM
Ex Int.
.100 60.2 80.1
.150 87.9 120.5
.200 112.2 162.1
.250 130.6 196.3
.300 150.6 227.4
.350 171.5 250.9
.400 187.6 289.2
.450 203.3 300.4
.500 217.0 311.9
.550 233.9 315.1
.600 245.0 320.1
.650 249.5 320.9
.700 249.4 318.5

Here are my current flow #'s.
Current heads
.100 78 I 66 E
.200 147 I 124E
.300 209 I 164 E
.400 255 I 206 E
.500 296 I 229 E
.550 312 I 232 E
.600 322 I 237 E

PLease help guys. I want to see 500 + rwhp!

VIPRETR2

iTrader: (63)

The new heads look much better in terms of mid/low lift numbers. That will help alot. I'd look at some ETP heads if I were you. Also, upgrade to a ported NW/FAST90 combo. I would also go bigger with the cam, that's pretty good sized duration but you could use some higher lift IMO. I'd run you current one on a 346, a 408 can take alot more than that (if you have the p/v clearance). I ran a 242/246 .595/ .595 110 on a stock bottom end LT1 and it drove fine and pulled hard. You could probably do better in the exhaust department with a 1 7/8 to 1 3/4 stepped header or even a full 1 7/8. Good luck.

CuNfUzEd

iTrader: (14)

Thanks Vipretr2. I will be getting the FAST 90/90 setup. But I have only had the car for a couple of weeks and I just got a strage 12bolt with 373', drag lite's W/ slicks and new heads, Fuel system. So my budget is hurtin' fur sure! I am picking these heads up for an even swap. Couldn't resist.

VIPRETR2

iTrader: (63)

Ah, I see. Well the heads should help, can't lose on an even trade!

rncotton

Hmmm .. that car sounds familiar.

I hope you get the issues resolved.

krexken

Your current heads are 63ccs at 11 to 1 and the new heads will put you at 12.4 to 1? Sounds like a custom chamber or a bunch of milling. I'd be finding out how much they've been milled. Personally, you current setup would suit me perfectly having more torque than horsepower. Ought to really get you moving out of the hole once you get that 12 bolt glued to the pavement.

VIPRETR2

iTrader: (63)

HOLY CRAP! I missed that whole line about compression. That's a tad high for a pump gas LSX, IMO.

CuNfUzEd

iTrader: (14)

Yeah I have thought it over too. The heads will get a thicker gasket. Which should bring them down to 12.1.1 Which should be okay for 91 Octane( *******! That's all we get here)
mcotton what gave it away? The twin turbanator setup? LOL

CuNfUzEd

iTrader: (14)

Oh yeah they have been milled .20

CuNfUzEd

iTrader: (14)

Also what kind of HP loss does a flash SES light cause? It comes on and stays on or it will go off completely or it fricken flashes. I will be having ED Wright tune it soon. But what do you think I am loosing from it?

krexken

Depends on what's causing it. One of my rear O2 sensors is bad which keeps my light on but doesn't affect performance at all. You ought to stop by a shop and get them to scan it for ya. Only takes a minute for them to tell what it is.

00ws6trans

oxygen sensor wiring

--------------------------------------------------------------------------------

The oxygen sensor harness has the following wires for the oxygen sensor:
Purple
brown (12v+)
brown (Ground)
Tan
Which is the signal, heater wires?

Thanks!

gnx7

iTrader: (28)

If you need slightly higher octane you can always add some Xylene (approx $5-7/gallon) to the tank. It is 117 octane and if you do the math 15 gallons of 91 and 3 gallons of 117 would put you at about 95.3 octane which would be enuf for 12:1 compression and healthy timing. Add 1 ounce of Marvel Mystery Oil (MMO) per gallon of Xylene for cylinder lubrication.

You could always back the timing down for 91 for street driving and then have a program for better fuel when you go to the track.

The Buick GN (turbo V6) guys have been using Xylene since the early 90's when they discovered the F1 road race cars used it for brewing insane octane ratings (130+) in their turbo motors for 40psi+ boost.

* Note* do not exceed 30% Xylene per tank of fuel or cold start problems will arise. Also don't spill any of this on paint. It will eat it for lunch.... wash off immediately. It is essentially a solvent.

Here's a good recipe101:
7 gallons of 91 octane
3 gallons of Xylene (117)
3 ounces of MMO
= 98.8 octane
* compare this to 5 gallon jugs of 100 octane premixed fuel for cost...?

LSs1Power

iTrader: (5)

The solution for your application is a larger cam 250 range with .620-.630's lift and 110-112LSA, 90mm Intake Manifold, 90mm TB and better heads such as the 240cc ETP's. I bet 500whp would be possible.

BADSS

iTrader: (7)

I think 12.4:1 static compression is going to be too high for pump gas, but you need to compute your dynamic compression ratio to know for sure. Your cam isn't very big, so I think your DCR will be too high for pump gas.

IMO, I would shoot for 11.5:1 static compression ratio, max.

MMS as in Morgan Motorsports? Mike Morgan did some good work and a fair amount of shoddy work back in the day- I would definitely have those heads independently flow tested before I put them on the car. They may be worse than the Patriots you have now.

Things I would definitely consider for your setup:

1.) underdrive pulleys,
2.) FAST 90mm intake (have it ported by someone reputable) & 90mm TB (I like the Nick Williams TB),
3.) 85mm MAF,
4.) better heads- ET Performance, AFR 225's, or TEA would be my choice,
5.) MAYBE a bigger cam- mid to high 240's duration, more lift- but IMHO, not sure you need it, I would look at changing the cam last.
6.) If you already have the MMS heads, you could send them off to a trusted porter- Ed Curtis, Brian Tooley at TEA, Craig Gallant at GTP, Trevor Johnson-
have them flow-tested and reworked if necessary. Would be cheaper than buying a new set of heads. Ed could also spec you a custom cam specifically tailored to your combination and flow numbers.

Good luck!

SideStep

Stop worrying so much about your static.. find out what your DCR is and go from there... H/C 346s like 8.4 - 8.5. I am not sure what a 408 wants... I have run a DCR of 8.60 with no issues on 93 octane but that is too close to recommend with confidence...

If you cannot figure out your DCR send me ALL (.006, .050, .200, specs) the cam specs along with chamber sizes, gasket thickness, piston dish… I will figure it out for you….

CuNfUzEd

iTrader: (14)

sidestep I will do that. Thank you.

SideStep

DUDE!!!

I did you current DCR, I assumed some data.. like the cam is a XE-R lobe profile...

Current setup:
Static: 11.12
DCR: 8.35 (which is fine)
-7cc piston (assuming)
Approximately .060 head gasket (assuming)

Changing only heads (to what you say is a static of 12.4) would require a chamber size of 54cc ( ), that being said:
Static: 12.4
DCR: 9.25 (no way in hell is that going to work on pump gas)
-7cc piston (assuming)
Approximately .060 head gasket (assuming)

I like the current DCR. What are your current intake runner CCs? I think that is where your missing HP is. You could still go to the MMS heads and retard the cam that 4 degrees and end with an approximate DCR of 8.9, still to high for 93 octane by my guess...

Once again, I am basing this on some guessed data...

CuNfUzEd

iTrader: (14)

yeah the new heads are 53cc chambers. Ah well I will just leave it as it is. Maybe port and polish my patties for some extra go. Now to figure i=out what cam would be best for street/strip use.

SideStep

Not sure what your $$$ situation is but a set of 225 AFRs would fix the guessing if you have good heads or not issue... and get you the most HP out of that 408....

That being said your cam has too much advance in my opinion for a stroker. 383s, 402s, 408s are all going to make good TQ. No reason to bias the cam for more TQ (by adding to much advance) and kill top rpm power in the process. Look for a cam that the IVO is slightly closer to TDC, compared to the EVC. It will give you longer legs in the RPM range. Rely on all that displacement to keep the low-end TQ up. Remember it is a balancing act; try not to kill too much DCR. The balance is much more critical for us lowly 346 drivers compared to you stroker types...