I am asking for an education here because I know you motor heads have the answers. I saw a super charger kit on Craigslist for sale today for $3500 used. The ad says it came off a early C4. Whatever my question is more about I read that you can spin and L98 beyond 4500rpm and it is wasted energy ? I have a cam that now lets my engine hit 5500rpm. Along with upgraded air intake and exhaust I thought this was all good ? Am I making good power beyond 4500rpm ? I saw a stock 1990 for sale with a super charger. I asked if it had any other work done and he said no all stock ? I lost interest and walked away. I felt that unless you change the air intake as well as exhaust that other mods are pointless aside from maybe roller rockers. GREGPENN advised me that heads if any mods for me are the way to go. Being that I have an automatic I feel my mods are done for this car. If anything from here on out would be to buy a cheap 93-96 and stroke it along with a cam change. But back to my original question Is my new RPM range quality power or am I just tearing my motor up by spinning the hell out of it ? I had my stock heads ported and gasket matched to stay in line with the air flow and exhaust but no bowling.

 

Put the car on a dyno and you'll know for sure in a few seconds. Superchargers make power right off idle so I wouldn't think you would have to spin it to the moon to make power.

 

I don’t remember (in prior conversation) if we talked about supercharging. Even so, for the same price as a used supercharger, you can buy good heads, revamp the block, and have something bullet-proof for years. There might even be room left over for a different intake (to compliment your cam).

By contrast, that used supercharger might be a time-bomb waiting to throw guts all over the place. They can also be harder to find a competent tuner.

Also, the "mechanical" dynamics of a longtube intake can not be overcome. No matter the cam, you're still suppressing the top-end potential of a motor. A cam can raise power across the entire torque curve (which means you'll feel it), but it won't magically give it a short-runner-like response.

I would also suggest that heads, cam, intake, and headers would be most builder's "foundation" before even considering supercharging. When I first setup to mod my low-mileage L98, supercharging was my first thought too. I decided a fresh stroked motor could last longer and provide more power.

 

I would spend my money on heads before anything else as you suggested quite awhile back. The subject of a supercharger never came up. It just raised the question of am I making useable horsepower at 5500rpm ? Is any TPI super charger or not above 4500rpm making useable horsepower ? Or is the limit on air coming in ? Thus mini ram or full ram air to over come that hurdle ? But then you might as well change the heads ! Resulting in a 350 core block and tossing the TPI aside ?

 

A supercharger is going to force more air into your TPI intake no matter what. Your car will make more power all the way to atleast 5500 rpm IMO. If you are seriously thinking about adding a S/c to your car, I would do ALOT of research and make sure you get all of your ducks in a row. If it comes with the cheap in line pump/ FMU system you will want to do away with it without even putting it on your car. To keep everything safe and not bust a bunch of ring lands on your stock cast pistons from detonation you will want a competent tuner and a real fuel system in place. Even if you are only running a small amount of boost, you need proper tuning.

If you have a stock engine I would consider a intake, heads, cam swap instead of a blower. It will be more reliable, require less tuning, and last alot longer. Superchargers and turbo cars are absolutely awesome and I love the feel of my procharger on my car but it was a ton of work to get it right and trouble/worry free.

 

Get a tried and proven kit from Procharger, Vortech etc. Best talk to Blowerworks they have been there and done that, as for rpm limitations that is limited by camshaft choice in some way. Standard cam will say idle to 4,500 or so that is what governs your rpms.
I remember the standard TPI would run out of puff at around 5,000 rpm, you could rev it a bit more but no useable power above 5,500 on the standard engine.
With my 383 blower, intercooler. TPI i went over 6,000 rpm by accident during the running in of the new engine, it rockets away from idle till where i decide to pull the foot from the accelerator and goes past 6,000 rpm and pulls no problem.

I have been there and done that with high rpm engines in previous cars, with the right build 8,500 rpm no problem every day but the critical piston speed is exceeded where the bores wear very rapidly.
If you want a high rpm pig of a car in anything but a racetrack ditch the TPI.

You can supercharge and turbocharge whatever rpm you want, just look at the nitro drag racers.

reliability and high rpm doesn't go together, however torque and less than 6,500 rpm h/p very reliable.

I now have similar h/p at way lower rpm no chocking coughing and stumbling below 3,000 rpm. Power from idle to 6,000 in any gear any speed there is no pig behavior from the blown engine, a grandma could drive it to the shops idles smooth and starts easy. The gas pedal needs to be treated with respect though.

 

The L98 engine will make power up to 4500 rpm (due to the long intake runner length) after that, the engine will stop pulling even though the engine rpms increase.

So, any engine can rev past 6000 rpm but, will only make power (or keep Pulling), up to a certain rpm range depending on Intake design, Head design, Cam specs etc...





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