95VertZ

Hi everyone! I just purchased a 1995 Z28 A4 LT1 Convertible. Im wanting to achieve somewhere in the 400-450hp range but not sure what is my best options to achieve my goal. Im not very car/mechanic savy, im a contractor by trade but am willing to put in wrench time and learn as i go to help save some costs. I know you'll need some info on the car to help so here goes.
Car has 136k miles on it*
Engine was rebuilt @ 133k (i have paperwork to support)*
I was told the previous owner had a cam installed during build but i can't find that on the build sheet.*
Also told there was a bigger converter installed as well. There again, no idea how to be sure.*
New Opti*
Flowmaster muffler but stock pipes*
Aftermarket cone air filter but on stock intake piping*


Any advice/help on where to go to gain the hp would be appreciated! TIA

Injuneer

Welcome to CamaroZ28.com ! ! !

Are you looking for 400-450 HP at the flywheel, or at the rear wheels? That's typically about a 17-18% difference through the 4L60E auto trans. The factory 275 HP rating is at the flywheel. Stock engine with auto trans will generally net 230-240 HP at the rear wheels.

Achievable either way with ported factory heads, and a matching cam, specific to your application. Typically need a cold air intake, 52mm throttle body, larger injectors, headers, full 3" catback, PCM tune, depending on whether it's flywheel HP or rear wheel HP.

Will require drivetrain and suspension mods to utilize that amount of power effectively, again depending on how you plan to use it - straight-line drag racing, auto-x/road racing, or just a fun "driver".

95VertZ

Just looking for a fun driver with the occasional straight line run. This car is a 2nd ride so it might see weekends only. As far as rwhp or flywheel.. doesn't matter. Id like to have it at the wheels but as long as its pretty stout compared to how it is now, im satisfied.

JakeRobb

Worth noting that a heads/cam LT1 car at that power level is not to everyone's taste. You could also get there with a supercharger kit, and you'd do so while maintaining a higher level of drivability. It'll probably cost more though.

95VertZ

Checked into the supercharger route, don't think i want to spend that much on it just yet. Id like to stay under the 4k mark if possible.

Injuneer

Good source of head porting and cam:

http://elliottsportworks.com/

Look over the descriptions of the three levels of head porting, then click on the cam tab to see the cam choices.

Other items, ballpark cost:

1.6X full roller rockers - $250-450
Lifters, pushrods - $125-200
CAI - $150-250
52mm throttle body - $250-350
Larger injectors - $150-350
If fuel pump needed (e.g 450 HP at rear wheels) - $150
PCM tune - $250
Long tube headers/Y-pipe - $400-1,200
3" mandrel bent catback - $350-850

Depending on what stall your current "bigger" converter is, you may need an even higher stall with the higher HP cams, and you may want to consider a set of 3.73:1 rear gears. At 450 rwHP you are probably looking at a 4L60E trans performance rebuild.

Then there are suspension items like tubular rear lower control arms (LCA), LCA relocation brackets, tubular panhard rod, tubular/adjustable torque arm, subframe connectors, upgraded shocks, etc.

95VertZ

Well, i have an issue. My intake manifold seems to be leaking oil out of the back side next to egr. My question is this, is there a performance upgrade thats worth doing while im going to be doing this fix? To save the hassle of having to tear this intake off again later for any reason?

Injuneer

The intake has to come off to do a cam install.

4th Gen LT1 F-body Cam Removal

4th Gen LT1 F-body Cam Install

..... and to swap heads.

Are you sure the oil isn't leaking from the oil pressure sensor?

http://shbox.com/1/op_sensor.jpg

The intake leak is very common...... but check the sensor first.

95VertZ

I originally thought it was a rear main, the oil was found coming out of a weep hole in converter cover. Took cover off and rear main was dry..noticed with a mirror that when car is running i get seepage from back corner of intake where sealant would be. I understand that they only have gaskets on sides and sealant front and rear. Will check pressure valve also but i didnt see any leaks from it. With this motor being rebuilt, i wonder if maybe they started engine too soon and sealant just didn't have enough time cure.

Injuneer

The typical intake manifold leak can be found by taking a paper towel, reaching behind the intake manifold from the passenger side and wiping the block below the manifold. Typically not near the EGR valve. That's why I suggested you check the oil pressure SENSOR.

Yes, the leak can be caused by failing to wait for the RTV to cure. Also, improper torquing of the manifold, not using dowels in the bolt holes to guide the manifold into place, incorrect RTV, etc.

95VertZ

So this morning ive been thoroughly checking back of intake and oil sensor area. I cant find any fresh oil at all. Ran car for about 5 minutes still no leaks seen or felt behind intake. Thats the good news. Bad news is, i pulled out the dipstick to check the oil level and low and behold my dipstick was broken off about 2 inches from the end. Its still down in tube. How in the world can this be fixed without taking oil pan off? And will it hurt to run/drive the car ?

Injuneer

Broken off 2" from WHICH end? Hopefully you mean the top/handle.

If so, pull the tube. One bolt holding it to the block. I've done it with engine in car, doing a header install. Put a strong magnet on the tube so the blade of the stick will not somehow slide into the oil pan.

If it's the bottom end, it's probably no longer in the tube.

95VertZ

Unfortunately it was the bottom end of the dipstick and im afraid its right at the end of tube if not already in oil pan. I went and bought a cherry picker (engine hoist) to lift motor to give clearance to get pan out. It looks to be a bit of a task so im not thrilled to start on it just yet lol. I thought about trying to pull tube to see uf im lucky enough to find dipstick end but if u break it, im prepared to pull pan also

95VertZ

Well, the time has come and I've decided to dive off the deep end of the pool lol. I'm currently in the process of dropping the engine (the bottom route) and will be adding all the goodies before buttoning it back up. I figured while I must repair the leaking intake and who knows what else, let's just do it all while we're going. Now, my question(s) for you guys is this..I have a parts list somewhat put together that I will be ordering off of over the next few days/weeks to get here once engine is finally free. If there is something I'm missing or maybe doesnt seem like a good choice, please let me know. Afterall, I am certainly a NOVICE at best with this. I am learning as I go but having a blast! Also, would I need to have the block bored out to bigger CI in order to do what I'm wanting with these upgrades?, keep in mind engine was rebuilt less than 5k miles ago... Ok, here's my list of goodies..

* LE1 heads w/ 232/240 .578/.574 110 LSA custom cam (could run a 218/224 cam without having to change converter to save $$)
* Professional Products 52mm Throttle Body
* Pacesetter LT Headers
* Pacesetter ORY
* Summit Racing CAI (same as K&N FIPK)
* 1LE Elbow
* 30lb Injectors (any suggestions on which ones? and will 30lb be good or ok to stick with stock?)
* 3.73 rear end gears
* 3" catback exhaust (undecided on brand)
* 4l60e shift kit (possibly)
* PCM Tune

Now, I know Injuneer suggested 1.6 RR and lifters/rods but I have no idea on how to select good options on that to work best with the route Im going so if anyone can point me in right direction I'd appreciate it!

That's where Im at so far guys, I have learned so much from looking over past posts and shoebox with all his tutorials/guides I'm hoping to one day be driving my car again lol!

Injuneer

Looking over your list:

- sort of two extremes on the cam.... one is fairly mild - good bottom end, other is fairly aggressive, and borderline on driveability - needs high RPM, harder to tune, potential surge. Why not something in the middle, like the 226/232 .578/.574 110 LSA? Or better yet, speak directly with Lloyd and give him your "wants" and maybe he has an even better recommendation. With the 3.73 gears, maybe you don't need to get the higher RPM stall right away.

- Not positive, but I think the lift numbers for the LE cams are based on 1.6X rockers. Might want to verify. Best rocker is the Comp Cams Ultra Pro Magnum, but they are on the expensive side. If you could find a set of the discontinued Pro Magnums at a decent price, more than adequate.

- I think that 30 #/HR injectors are too small, not meeting the minimum rwHP quoted for the LE1 heads, with smaller cam. Definitely not going to make the HP that setup is capable of with stock 24 #/HR. You should consider at least 32 #/HR. Or just go with 36 #/HR to give yourself some head room. On a cool, dry day (assuming you are near sea level, not somewhere up in the mountains) you can make more power than shows up on a chassis dyno chart w/ SAE or STD correction, so you need the fuel there "just in case". Or what if you want to make some other small change that picks up a few HP. There is no "down side" to oversize injectors, unless you go crazy. The engine will run the same with 32 or 36's, provided the tuner enters the correct flow numbers in the program.

Just looking at the LE website, you could be putting down 390 rwHP with a middle level cam. Through an automatic, that's about 460 HP at the flywheel. Using the guideline I worked up and have been using for years, multiply flywheel HP X 0.07 to get minimum recommended injector size. 460 x 0.07 = 32.2 #/HR

- I'm weak on an auto trans mods, but I think you can accomplish the same things you get with a "shift kit" through tuning. Check around on that one. The Firebirds even came with a "performance" shift button, that tweaked the PCM to firm up the shifts.