Newbie questions on Supercharged LT1

Nuvolari · 12-31-2003, 07:23 PM

Hi All,

I'm totally new to American cars and LT1 engines but I am in the process of putting a road race car together and have some questions. I just pulled the engine on my 92 LT1 and am wondering what I can do to build a good reliable road race engine. This is what I have right now:

LT1
Vortech Supercharger running a 6lb pulley (I also have a 12 lb pulley)
Water injection
Balanced
8.8:1 compression
28lb injectiors
computer I'm not sure on
stock headders (I know they have to go so any suggestions)
no idea what cam is in it

I'm looking at putting a very reliable road race engine together. Cost is a major concern but I'd like to do things right at the same time. Any imput would be greatly appreciated on what direction to take.

Bruce · 12-31-2003, 10:18 PM

If you are going to run only 6psi, then the c/r should keep it at 9:1 or 10.0 that way you can make good hp with 6psi of boost pressure.

Running a 8:8 c/r and 6 psi are not in a good mix. Based on your 6psi setup, that you will not build any boost until at least 3000rpm. So While you are not under boost, you car will be weakling 355ci or 383ci for that matter.

You are talking about that you also have the 12psi pulley. Well that 12psi pulley is useless if you are going to use the Vortech supplied serpentine belt. IT will slip at more than 6psi.

If you are running 15+psi of boost then your 8:8 c/r is a good choice.
Take a look at the pic you will know what I am talking about.
Also, you say cost is a concern. Well the belt coversion will usual cost $1000-1500.

Bruce
383LT1 Supercharged

The supercharger got it own belt and spring load tensioner

Nuvolari · 01-01-2004, 01:10 PM

I looked at my pulley setup and it is like Bruce's drawing. The SC belt has its own tensioner so belt slippage will not be a problem. I guess I got lucky on that one. With that information, is running the 12lb pulley a good idea for road racing (reliablility is my #1 priority)? What size injectors should I run or are the 28lb ones ok? What is a good compression ratio? Should I use special rods? Cams? I'm really green on all of this so any good advice would be well appreciated.

BAM92 · 01-01-2004, 01:53 PM

Just curious, what side of the serpentine belt is your blower on, radiator side or engine side. Most road race engines I see are N/A not blown and are high compression. I guess it depends on what class you want to race in. I would definetly say you need bigger injectors. I am going with 42lbs on a 383 with 10 psi and water injection. Also you need to go forged components through out. You probably are going to have to address the heat issue as I would assume you would be making alot of heat with a continual load on engine, lap per lap. As for motor specifics these guys in here are better about the specifics than I. Happy New Year.

Bruce · 01-01-2004, 02:23 PM

Does your vortech kit came with a new balancer?? if not, that means you are using a serpentine drive. True the vortech kit got it own tensioner but it does not got it own belt.

You should be at least use a set of 42s or 50s injector. How much $ you want to spent is totally up to you and can be a few $1000 different in parts alone. You can do a budget rebuilt 355ci reuse the stocker crank and rod. go with a set TRW 21cc "D" Cup piston That should give you a 9:1 c/r with your LT1 heads. The stocker crank and rods with TRW forged piston can easily handle 550rwhp. Keep your RPM under 6000rpm Most of the people here are know Shalin. This same setup with 12psi he got 575rwhp
Cam, there are many choices. Yoy can use cc 220/230 @.05 540/540 or CC218/230 @.05 .5../.5.... lift or 224/236 @.05 .5.../5... lift you can get all this infor on the compcams.com

Do you have a balancer like this????

[Modified by Bruce, 12:41 PM 1/1/2004]

Nuvolari · 01-01-2004, 02:53 PM

The belt on my blower is on the engine side. The balancer is exactly the one that Bruce posted in his picture. When I got the car the blower was already on it and I am learning about the kit as I go along. I'll look into the TRW forged pistons while retaining the stock bottom end. I'd like to see 500hp at the flywheel. I believe that this number is achievable both reliably and cost effectivly. With regards to software, do I have to change the factory chip and if so change it to what? I appreciate everyone's time and feedback. Happy New Year!!!!

Bruce · 01-01-2004, 03:18 PM

You are lucky. People out there paid a lot of $ for that conversion. You already have the 8 rib setup. why not pulley it up the 12psi? you should not have ny problem with the TRW pistion in place.

Tuning is very important and is A MUST DO. If you car is a 1994 and up you should contact TJWong he does custom eprom burning. He also has a 396LT4 with T Trim blower. He can help you for your Eprom. If it a 1992-1993 speed density I would only have Shalin do the tuning because the speed sensity is very tricky to tune for maximum hp.

ps. I just noticed you say when you got the car the blower with 8 ribs is already on it. I would doublt that you already have a forge piston it in. Usually people are doing the 8 rib conversion because they want to make more hp with high boost. You might already have a 355ci motor or.

Bruce

[Modified by Bruce, 1:23 PM 1/1/2004]

BAM92 · 01-01-2004, 10:27 PM

I asked which side your blower was in relation to belt to see which system you have. You have the Vortech designed system as mine is by Carroll. My blower sits on the engine side with the belt side facing the radiator. Do you have the water injection controls in the interior of car. Also where is your water storage? Do you have a bag or does it use a bottle?

Nuvolari · 01-04-2004, 02:13 PM

My water injection is controled automatically as it is programmable with 3D delivery mapping (The manual is like a phone book) and I'm just learing about it right now. My water tank is about 1.5 gallons and made of alluminum. It is located in the back parcel shelf area. Remember that my car is a gutted race car so the placing of items is primarily for weight.

Who is this Shalin guy and how can I get a hold of him?

kverges · 01-06-2004, 01:10 PM

Shalin Patel can be found at two1bar@yahoo.com. Some years ago , he had an impressive LT1 Vortech supercharged car and he was a huge help in building my LT1. My car is very similar to his, but I use water injection and he used intercooling. He made more power than I did, too. Shalin is a drag racer, though, and you need to consider that the power you want will place large demands on your cooling system, brakes and the rest of your driveline. I have tracked my S/C LT1 and don't do it often because it absolutely eats brakes.

Now you say "road race, " but in what class? About the only SCCA class you might be able to run is ITE, and I am not sure S/C is legal in ITE anyway.

I road race, too, but race completely different cars, Spec Miata and Formula Mazda. I can assure you that good handling, good brakes, and driver skill will net you much more in lap times than extra power.

I recommend that you make NO engine changes, other than for reliability (such as oil cooler, larger radiator) and focus on sorting out the car and making sure your lap times are reasonable for your combination and you don't have problems like brake fade. Make sure the engine runs cool oil & water temps, holds oil pressure, does not throw belts and does not puke fluids from the breathers. You may also fine the power steering gives you fits and needs extra cooling.

There is nothing more frustrating than having lots of power but issues that keep you from using it.

Don't be a typical big power car driver and have no skill other than standing on the loud pedal and holding up traffic in every brake zone and turn! I see a lot of that and rarely does a Vette lap faster than my 110 rwhp Spec Miata at my home track.

I strongly advise getting on track and soring out the car before going for any more power. You'd be surprised how the details can eat time and money

[Modified by kverges, 8:16 AM 1/7/2004]

[Modified by kverges, 8:17 AM 1/7/2004]

Nuvolari · 01-07-2004, 11:08 AM

Keith I thank you for the contact information and words of wisdom. Please do not consider me some rookie who is power hungry and nothing else. I have been road racing for over 12 years now and have sampled all kinds of machinery racing in Canada, The USA and in Europe (mainly open wheel but some Touring cars too). This Corvette is to be raced in Canada to specific rules. The power is a necessity and the brakes and suspension are being well tuned to handle the extra grunt. Few things are more frustrating that the guy who is fast as hell down the straight but piss slow in the turns. I can assure you that this car will be very quick everywhere.