Hi all,
Long time visitor of the site but first time poster. I have a 1999 Firebird Formula with a 347" LS1 that I initially had put together around ~4-5 years years ago while I was still in college. The car didn't necessarily perform like I'd have liked it to, but it wasn't the best match of parts and I worked with what I could within my budget at the time. The car served as a nice weather daily for the last few years, but now i'm looking into improving upon what I have and "doing it right" (the second time around unfortunately). The car made 410 RWHP, and on it's only track passes went ~11.70's @ 116 with a lame 1.68 60 ft. The DA was around 2600ft and it was HOT, but still off where I feel it should perform considering what people are doing with way less. The setup is as follows...

1999 Firebird Formula. Full weight outside of spare tire.
347" LS1, Mahle flat top pistons with -4cc reliefs, Scat I beam rods
AFR 205's, no additional port work, Milled 0.040 w/ .041 cometic gasket.. should be a little over 11:1
Tick Performance cam, 229/232 dur, .614/.575 lift. Tick dual valve springs
Stock Rockers, LS7 lifters
LS6 Intake, slp lid, stock maf, free ram air mod
1 3/4" Headers, TSP Y Pipe, stock catback with magnaflow muffler
A4 4l60 trans, Yank SS3600 stall, Moser 12 Bolt with 3.73's

Since then, I've went to a Performabuilt Level 3 4l60e, with an FTI hard hit 4000 stall since I plan on staying NA. I've also changed from a Y pipe and catback, to the speed engineering true duals after seeing the results Mavn and others have gotten on heads/cam cars. I picked up a Tony Mamo ported FAST 92 intake as well as a FAST 92mm throttle body but haven't gotten around to installing it. Just looking at other suggestions that I could also do to improve this setup, as I live pretty fair from my tuner and would like to be able to get the retune knocked out in one trip and one day on the dyno. Which leads me to this...

-Do I look into a new cam? I've emailed a few different vendors, and most have recommended me towards a larger cam (230-240 duration. 620 lift sized stuff)
-Do I keep the cam I have and spend money on different/new heads? The trickflow and PRC stuff looks pretty nice, but would add a lot more price wise
-Would it be worth swapping to a larger diameter lid and going to speed density or a larger diameter MAF when I install the FAST? I've read a lot about it but have seen a lot of conflicting information

Sorry for the book. Any and all advice, suggestions, hazings are appreciated and welcomed (yes I should've just stuck with bolt ons first and could've went faster.. hindsight is 20/20)

 

I wouldn't change the heads or cam, not enough gains to be had to justify the cost. If your looking for significantly more power, you probably need to look at forced induction. You could sell the heads and intake to help offset the cost of a supercharger or turbo.

 

I would love to do a procharger build, but that would be a long ways off. I think for the time being, if I could make an 11.0/10.99 pass with the stuff I have and what I’ve picked up for it so far, I would be pretty happy. Another thing I’m considering is some weight reduction, bumper supports/k member/ A arms, front coilovers, light weight battery, wallet stuff that would help make up for being down on power a little bit.

 

Xray,
The addition of the true-duals & the MMS FAST 92 will subtract .4-.5 from your current combo and add 3-4 mph in the same
conditions as previous, in good air even more. The Chris1313 Ram Air would be a good addition also. The Heads are
the last thing I would change given your goals. If I were to change the cam (not necessary) I would do a
Cam Motion Low Lash Solid Roller something like 236/242 (subtract ~5* for hydro equivalent).
Search Thunderstruck (Sticky Above), Darth V8r, & Speedtigger threads for results with the LLSR.
Can be done with stock rockers (bushing trunion upgrade suggested) If you are patient and precise.
I am also an enthusiastic LLSR owner.
My .02
Good Luck

 

One thing you could simply work on is your suspension and get that 60’ down. You have the power now to run close to or maybe even hit the numbers you want.

 

Looking for power NA, I'd make changes to the following items.


LS6 Intake - a 90mm/92mm snout Fast and matching TB will help. Ideally, ported.

slp lid, stock maf, free ram air mod - I'd get a bigger 98mm lid or similar, 85mm MAF or go Speed Density, at least Fast Toys Ram Air or better

1 3/4" Headers, TSP Y Pipe, stock catback with magnaflow muffler - the headers are OK, but true duals will help. The stock cat back i pipe is narrow over the axle probably 2.75 inches or less, its a restriction and costs power regardless of the muffler used.

There probably 20 to 35 whp NA to be gained cleaning up the induction path and exhaust system with your current set depending on how far you want to go

 

I originally considered going the ported LS6 route, but a friend of mine sold me his Mamo ported FAST 92 and 92mm TB for a decent price since he was going to a Mamo ported 102 that already had a direct port on it. I have the SE true duals on the car currently and it does seem a little more responsive, but that could just be in my head since it wasn’t retuned yet. I’ll look into a bigger lid setup and ask my tuner on preferences between SD and MAF setups.
Right now the car has a set of Viking Warrior DA’s on the back with stock springs, and a mixture of UMI and founders parts (LCAs, panhard bar) but I can’t say I’ve done much in the way of adjusting the suspension or shocks past the street settings. We set the pinion angle when we installed the suspension pieces and 12 bolt but haven’t done much past that.
Yes, I’ve read through some of those threads! LLSR sounds like a possibility down the road if the additional bolt ons and adjustments leave me wanting more. It makes me feel better to hear that the heads are okay. I know there are a lot of newer options available now, but I know people have had success with the 205’s in the past. I’ll look into the chrs1313 as well, I’m sure there’s something to be gained over the cut stock bottom of the air box.

 

I wouldn't swap cam or heads either. You're already swapping stalls which is 1 thing I was going to suggest. As mentioned you need to take care of the kids and MAF if you're going to a larger TB and intake so it isn't the new choke point. Some weight reduction wouldn't hurt either. All that said, I didn't see any goals.

 

What rpm are you shifting at?

 

Looking for bottom 11’s. If I could make a 10.99 hero pass in mineshaft air in the fall I’d be happy lol. I plan on swapping out the SLP lid with one of the larger fast toys options and getting in touch with my tuner on their preference of aftermarket MAF sensors or if I’ll be going speed density. I live in Maryland so we get a wide variety of weather but the car really only sees the street from May until October. And yes, the SS3600 was fine for the amount of driving I did with the car but the car feels a lot better so far with the 4K FTI. I was holding off on weight reduction until I had some feedback on the heads and cam which I’m happy to say doesn’t sound like they need changed so I guess I can look into that sooner than expected.
Right now the car is set to shift at 6800. I’m thinking it could probably stand to see a little higher of a shift point though. With the old SS3600 it felt like it fell on its face a little after the shifts. Now with the 4000 FTI it shifts and I don’t think it falls back past 5900-6000 rpm’s

 

what tires are you running at the track ?

uncork that thing, that ls6 intake and stock cat back have it choked up imo

 

For just driving around I have a set of Nitto 555r’s. For the track I use a set of MT ET Street SS’s. All 275/50/15.

 

You’re on the right track man. Put the intake on, focus on bolt ons and the 60’ everything else will fall into place. Your goal et sounds reasonable for sure.

 

If you’re goals are strictly track, throw a bottle on it and let it rip. You can get a NX Proton system right now for under $400. My 02, stock bottom end, tick sns 3, and a 150 shot from a Proton kit made 550 to the wheels and 630ish torque.

 

Back when I did the rebuild, nitrous was what I had in mind and why I went with forged pistons and rods. That would actually probably be a decent system for me because I don’t think my converter would like anything more than 100 shot before it would blow through. I’ll probably see how the car runs NA once it’s sorted and if I need a little more look into one of the cheaper nitrous kit offerings from one of the sponsors. What all accessories do you run with your’s?

 

I ran a window switch, LNC-2000, bottle heater and purge, pulling fuel off the rails back then.

 

I wouldn’t touch the cam unless it’s more of a track car. Then change it out to something bigger. I think what has been listed here is a good start bigger lid, 85mm maf, changing the exhaust which you did and get a ram air setup whether it be Chris1313 or another one. I bet if you ran that pass but with zero da you would be around 119 mph and in the lower 11s. You need more seat time to better that 60’ too. I’d do all those things get a good tune then hit the track and work on the 60’

 

The car never 60 ft’d like I would’ve liked it to and never felt like it left hard with the 3600 converter when it was a bolt on car, cam only or with the addition of the heads. The 4000 definitely feels better as far as shift extension goes but I haven’t had a chance to launch it with proper tires and prep. Hoping I can get the 60 ft down into the low 1.5’s

 

Those heads flow enough to support way more power than you are at now. You will be wasting money getting a different set of heads.

I don't know the flow numbers on those heads but I'm guessing they flow more than 300cfm. On paper that should support at least 600hp flywheel. You are far from that

As others said, I think money will be better spent on induction.

 

Max effort, or even moderate effort, H/C/I LS1 builds were the biggest scam of the last decade. The ROI was never there. I know, I drank that Kool-Aid and fell into the pit of disappointment with my wagon - nitrous was added to make up the performance gap compared to my turbo 5.3L and Procharged LS2. The only thing that the H/C/I does better than the other two is the noise it makes - it is glorious by comparison to everything else in the fleet.

So, the short answer is: boost it.