Ptaylor459

Hey there guys! I thought I would come here for some advice. I'm looking to upgrade my 99 WS6 a bit more and know that this forum attracts a lot of knowledge and I feel as though I could get some great help here. So here it goes....

The Car:

1999 Trans Am. ~37,000 miles on the car and only a few thousand on the new power train. It has a 6 point cage, fully adjustable suspension with all the goodies. LS3 Stroker from Texas Speed, TH400 w/~4000 PTC converter(Revers manual valve body and transbrake), Ford 9 Inch w/ 3.70 gears and 35 spline axles. Some Weight Reduction (Front/rear bumper support, AC/Rear Seat removal).

The motor:

Fordged 418 cubic inch LS3. Pistons used are -20cc dish (I'll explain why in a bit). 244/248 cam with a .612/.615 lift at 112 LSA. Ported and angle milled 317 heads that yield 54cc Chambers. This is why I used a dish piston to bring my compression down to ~11:1. The heads and cam were re-used from my 383 stroker setup I previously had. The intake is a cathedral port Fast 102mm and ThrottleBody is Nick Williams 102mm. Stock air lid and stock MAF I believe. The car is setup with a plate kit for N20 from Nitrous express and is currently jetted for a 100 shot. I also have a stand alone fuel cell under my hood that I put C16 into. 42# injectors as well. Lingenfelter box(2step and timing retard), Window/WOT Switch for nitrous, Bottle heater blanket. The car dyno'ed at ~450 HP and 415ft/lbs on motor and ~550 HP and 515 Ft/lbs on the 100 shot. Power curve starts to die off at 6000. Its odd because with a 418 cubic inch motor and such a large intake I should be making power much higher. I imagine my heads are the limiting factor. Thats where Im looking to upgrade It has been running consistent times here in Dallas,Tx with our 95 degree heat. On motor alone, my best pass has been 7.14 at 96 mph with a 1.52 60 ft. My best pass on the bottle has been 6.59 at 104.5 mph with a 1.42 60 ft. This is with leaving off 2step at 4000 and flashing my converter. The car seems to dead hook.

Now I know this setup has a whole lot more potential. I imagine with the right heads and cam combo I will be touching 6.9x consistently on motor and lower 6.xx on the juice. I'm currently looking for some good upgrade options for my heads and cam. This is not my daily driver and has been mainly a strip car. It will also see some street action. The heads I've been looking at are Texas Speed's PRC 247 CC. Even if they mill the heads to 62cc from the factory 67 ill still be sitting at maybe ~10:1 compression. Also my current cam has ~22 degrees of overlap and the cam I'm looking at has ~28 degrees. I imagine the idle will be much harder to tune. With a heads and cam swap ill also respec my converter. Not sure how nasty I want my converter to be given that I drive the car around town and to/from the track. The current setup is on a 100 shot and i imagine ill go no bigger than a 250 shot. Heres the specs to the cam: 245/256 .657/.655 with 1.8 rockers. I will run 1.7 rockers. LSA is 111. This cam is TSP LS7 Stage 3.5. I'm basically looking for some of the best cathedral port heads on the market that I can bolt on to my setup and keep my compression fairly close to where its at now and fully utilize all of my cubes. I would also get a cam that would work well with nitrous and respect my converter for my new power. A larger lid and larger MAF are probably due as well...

Any and all help is appreciated. Thanks!

NAVYBLUE210

Or MMS AFR LS3 Heads with Mid Length Runner FAST and pick up
40+ on Engine alone! 80+ on current combo.
390 CFM VS 340 CFM max for Big Cathedrals
and 500-1000 RPM with Mid Length Runners.

KW Baraka

iTrader: (7)

I thinking you'll lose a lot of torque below 4K RPMs and will gain HP at the top end.

With your gears and TC, you'll likely gain a couple of tenths in the 1/4....but it'll be a wash at 1/8th.

I wouldn't go through the expense, but then.....it ain't my car/it ain't my money.

Best of luck!!

KW

Tuskyz28

I think I'll go with whats already proven. It's a 408ci t56 bird on the site that run 10.5s with a 251/259 cam using the PRC 247 heads.

big hammer

This. The current top end is a pretty big restriction. Problem is keeping the compression up with a properly sized heads.

Mast small bore ls3's flow good and have a 61cc chamber out of the box... can easily shave them .030-.040 too

NAVYBLUE210

The small chamber MAST is probably the best option keeping
The current pistons.

big hammer

For NA I think so. Not sure they'd be great for n2o

KCS

iTrader: (20)

What pistons? It would be good to know what heads the valve reliefs are meant for.

Ptaylor459

Thanks for all of the input guys. To answer some of the questions, my pistons are 4.070 I believe and have a -20cc dish. From what I’ve been looking at, all of the LS3 heads out there feature a square port design instead of a cathedral port. My fast 102mm Intake is cathedral port so that is why I’m leaning towards a cathedral port head. I know that the bigger and badder option would be to go square port everything BUT I got that Fast Intake for a good deal. PRC 247 heads seem like a great combination of quality given the extras that come standard on the heads as well as how well they flow (.650 flows 355/241 CFM). $2399 for the pair as well. The MAST alternative would be the LS1 245CC 4.000”+ Heads. They come fairly bare at $999 and additions add up quick.... They flow at .650 363.2/240). Whichever option I go with I’d love some more input on the correct Cam. Doing some digging I came across a Bad B**** that BTR makes. Cam specs are 251/266 .63X"/.595" 112+4.....This one could definitely be overkill though given my intake setup. I know most guys running a setup like mine (400+ cube N20 stroker for the drag strip) will typically run a high rise intake. I really want to retain the stock intake appearance and don’t want to go that route though. As always, thanks again for all of the input ahead of time.

Jimbo1367

What about the PRC smallbore LS7s?