Pipsovich

Hello everyone!
My name is Peter, from sweden, and i have just purchased my very first american car with a real engine. It is a 1995 Camaro Z28 with a 350 LT1 engine and manual 6 speed gearbox. I love the car so far, but i feel that i would want even more power and some opinions on the mods that are done so far (by the previous owner)...
My goal would realistically be 400 whp to begin with.

Mods so far, motor has done about 15000 km with the mods:
Bored 0,02", original pistons , LT4 Hotcam kit,
Cam (dur218/228 lift 0.525/0.525 lobe 112)
1:6 GM performance rockers, heavy duty cam chain.
Elliot´s Port Work´s ported original heads (2.02" in 1.6" exhaust)
MadZ28 databox,
Rev limit at 6300rpm. CSR electric waterpump.
Hooker super comp short headers Ceramic coated. 3" exhaust.
Taylor ign cables. KN 4" air filter. LS1 Alu shaft.

My guess is around 350 hp right now? Could this be right?
My ideas are following;

Larger throttle body
Match porting of inlet
Another camshaft a bit more "racy"
Bigger injectors
New reprogramming/maybe run a MS3 ECU and get it properly tuned
Make a better air intake for the filter as now it draws in pretty hot air.

Please give me comments and ideas!
Thank you all

Injuneer

Which LE heads.... LE1, LE2, LE3? Was the intake manifold also ported? LT4 HOT cam is small. An LE custom cam will make more power. Tell him your goals and he will recommend a cam.

You should have at least a dual 52mm throttle body? Some will recommend 58mm, but engine dyno testing on my 381 cubic inch stroker LT1 did not need the 58mm throttle body I bought, for the 500 flywheel HP level.

You need larger fuel injectors. Stock injectors (programmed as 24.9 LB/HR will not even make the 410 flywheel HP needed to produce 350 rear wheel HP through the 6-speed T56 transmission. For your 400 RWHP goal you would be marginal w/ 32 LB/HR injectors. I would just go with 36 LB/HR injectors.

How did thy use the stock 4.000" diameter pistons in a 4.020" overbore? Does not compute.

You need to buy or fabricate a true "cold air intake".

The factory PCM (powertrain control module) will handle all the above mods, when correctly tuned. Finding a decent tuner is getting harder. Madz28 no longer does LT1 tunes. I run a MoTeC M48Pro but that is to support a 300 HP shot of nitrous, and 8 LS1-type ignition coils. Any aftermarket ECU needs to be compatible with the optical cam position sensor in the LT1's Optispark distributor.

JakeRobb

Congrats on your new car! I love when American muscle finds its way to Europe.

The way I read it, he has stock LT1 heads, ported by EPW.

I agree - call them and ask them to recommend a combination to suit your goals and budget. I suspect they'll recommend better heads as well as a more aggressive cam.

I think you'll find that the stock clutch will not stand up to the power. There are a number of clutches that can handle the increased power. I wholeheartedly recommend going for the expensive McLeod twin disc option -- anything else strong enough will be heavy and chattery.

Depending on your plans for the car, consider a lightweight flywheel when you do the clutch. Drag racing doesn't pair well with light flywheels, but everything else does!

You might also need to worry about the factory rear end. These units have been known to break starting around 400rwhp. You'll be right on the edge of the damger zone. A hard launch on a sticky tire (like you'd use on a dragstrip) is the most likely time it would fail. There are a lot of options here.

You might have 350hp at the flywheel with your current mods, translating to 300-310 at the wheels.

One thing I always wonder about when people come in here with specific power goals without any other context is where that number came from and how sure the owner is that they really want that much power in that car. So, I have to ask: once you have your 400rwhp Camaro, what do you plan to do with it? Unless you're a seasoned driver of high-powered RWD vehicles, you'll find 400rwhp to be shockingly and perhaps scarily fast. It's enough power to get you in trouble almost anywhere, almost any time.

Pipsovich

Thanks for the answers guys!

Of course the pistons are also overbore. I just felt that is was unneccessary to write that.

As for the clutch, When i get a new one, do you have any suggestions for a priceworthy clutch that will suit my needs?

The flywheel is lightened according to PO and the engine feel happy to rev.

Regarding the heads:
They are ported original LT1 heads and were supposed to be able to flow enough for a bit more cam, he had flow numbers in his mail and are going to send me them "If he can find them", the engine was built a long time ago, hehe.

The intake manifold was not ported. It is on the to-do list.
The throttle body is std. Is that what... 48 mm?

MS3 has actually got a Optispark-mode and can be tuned anywhere. That is why im considering that instead of the std ECU

Pipsovich

I dont think i will be scared of 400 whp, having owned porsches and various turbo cars at around 300, very used to driving rwd, car will be used to have a bit of fun mostly on street, maybe try it out on the strip at some point, what rear end do you recommend?

Injuneer

"EPW" is Elliott's Port Works = Lloyd Elliott = LE. He has three standard levels of porting for the stock LT1 heads.... LE1, LE2 and LE3. He will also do other custom porting based on specific needs.

http://elliottsportworks.com/

Injuneer

The stock rear axle ratio with the 6-speed manual is 3.42:1. I would recommend 4.11:1. With the two steep overdrive ratios (5th - 0.74:1, 6th - 0.50:1) in the T56, you will lose very little in terms of fuel economy.

But 4.11's in the stock 7.625" 10-bolt stock rear axle assembly just makes it a bit more fragile - see JakeRobb's comments, above.

JakeRobb

I knew they were the same. The part I didn't know is that LE1/2/3 are based on stock LT1 castings.

Agreed; 4.11 is a great ratio for a T56 car.

If you're interested in upgrading the entire rear rather than just the gears, the go-to options are the GM 12-bolt, Dana 60, Ford 8.8", and Ford 9". All of these are available as bolt-in replacements for your 10-bolt, with spring perches and the like already in the right places. Assuming you want to retain posi and ABS, expect to spend about $2500 US. Shipping to Sweden will surely add to that, and it may be tricky to find a vendor willing to do it.

Among those four, it's a bit of a toss-up at your power level. All are more than strong enough. They're all heavier than stock. The Dana 90 and the 9" are heavier and stronger than the other two; both will handle four-digit power levels. The 12-bolt and the 8.8 are strong enough for about 800rwhp. Given your power goal and location, I'd shop purely based on shipped price.

Pipsovich

Thanks for all the answers guys! As usual, when starting to upgrade a car it always get a lot more expensive than you might think at first...
Still happy with the car, though could have had a bit more power as previously stated.

Will the 10 bolt std rear be in danger with around 400 whp/normal street use? Ofcourse it will not last forever...
Also, the LSD in the Z28, is there anything i can do to it? Feels like the inner wheel wants to lose traction out of corners, but if i do a "Burnout" start both wheels will spin.
Normal or is the LSD on its way?

Pete

Injuneer

Let's see if I can find the links to two magazine articles showing upgrades for a 10-bolt. They put over $1,600 into the upgrades, and their final recommendation was, if you planned on drag racing on sticky tire's, that the upgraded rear axle assembly was limited to about 425 rear wheel HP through an automatic transmission, and not recommended for a manual transmission.

Some people have raced their cars into the 10-second 1/4-mile range with a stock 10-bolt. Others have blown the rears up with stock HP and a bit of abuse. Depends how much you want to gamble, and how much it would cost to have the car towed home after a rear axle assembly failure.

Here's Part 2. I'll have to look for Part 1.

Fourth-Gen 10-Bolt, Part 2 - Hot Rod Network

Injuneer

Part 1

Strengthening The Rearend From An LS1 Firebird Formula - Hot Rod Network