98 LS 1 Convertible, Dual Turbo Or Supercharger?

[Phoenixx]

I've looked around for the pro's and con's of each only to find extremely biased articles on both sides. I understand that turbo's have lag that the superchargers but heres what i was wondering. Would a twin turbo or a supercharged LS 1 be faster on a quarter mile? Which would be faster supposing im already going 45 mph? I understand these put out massive heat radiation especially the twin turbos what would i have to do to balance this? And is one of these going to be hard on my car, im not going to be constantly racing this or doing burn-outs and beat up on my car but would either of these wear on my car during daily driving? And how big of a difference is there between having one turbo and two?

Thanks, Any Advice Would Be Appreciated!

[ConElite]

Well whats your intention. How fast are you wanting to go. B/c you said it was a daily driver, You should look into the STS system. Its very easy on the engine. It does not create a large number of boost but for Daily driving its pretty good. If you go with Twin turbos your looking at a lot of $$$ and the engine is going to take a beating with stock internals. Supercharge is also a good idea. Less heat but with either setup your going to want to run an Intercooler.

As you said, Turbos do lag b/c they have to spool up to create that Pressure needed. Superchargers work off the speed of the engine so its instant.

P.S. Welcome to the forum.

[Phoenixx]

What kind of upgrades do you think i would need to stop twin turbo from wearing on the engine?

[lsdengines]

are you referring to a roots(magnuson) style supercharger, or a centrifugal (pro-charger). All a centrifugal is, is basically a turbo with a pulley and gearbox instead of a turbine housing. Here's my basic rundown for each.

Roots-These will produce a steady flat boost curve from about 1500rpm's on up. Until here recently they were not efficient at all, meaning they did as good a job heating the air as they did compressing it, however Kenne Belle is putting up some retarded efficience #'s with his new MASSIVE blowers to bridge the gap with the turbo cars. If your kit doesn't come with a boost recirc valve, you will be cruising under boost which is not very good for your engine at all. Since these replace the intake manifold, added clutter is kept to a minimum. Intercooling is difficult at best, and often not very efficient with these type blowers. Changing boost levels on these requires a gear change, and tuning is similar to a turbo car especially if equipped with a boost recirc valve.

Centrifugal-These will produce a linear boost curve in relation to rpm, not seeing the bigger boost #'s until higher in the revs. They produce very good efficiency #'s, and produce very good power. You will typically only reach significant boost when driving hard anyway, so not really much added wear on the engine as a whole. You are adding a bit of extra piping especially if intercooling, a large bracket, and sometimes relocating other accessories, so there is a bit of added clutter to the front of the engine. These are very easily intercooled either with a fmic, or an air to water type. Changing boost levels again requires a pulley change, tuning is relatively easy and similar to naturally aspirated, since the boost is progressive and not a sudden hit.

NOTE- with either type of supercharger, I strongly reccomend an sfi damper ,and on lt cars a keyed hub is mandatory in my opinion, to help reduce harmonics transferred to the engine from the blower.

Turbo-I am a turbo fan, but Im trying not to be biased on this. Turbos require the most thought to do right. You have 2 housings to size properly, 2 impeller wheels to size properly, hot and cold piping to size properly, but when all of this is done properly, turbos will produce a boost curve very similar to that of the roots style blower, very flat and coming in at 2500-3000, sometimes sooner, while being much more efficient(again, only if everything is sized right). When improperly sized, or using a cookie cutter kit, or having a race only setup and needing a turbo that large, you will have threshold times being in the 4000+ range(on our cars, imports, thats typical). There is a ton of piping and tubing, and fittings, and HEAT involved with turbos, and double that if using twins. Turbos are load sensitive, meaning they respond to the load being placed on the engine. ie. under light throttle, boost is never reached unless the turbine housing is too small. So often times, gas mileage, and longeivity of the engine do not change much. They are intercooled just as easily as a centrifugal. Boost is changed by changing the wastegate spring or by installing a bleed valve inline with the wastegate to change the signal sent to it. Tuning can be a pain since the boost can come in very suddenly and at a wide range of rpm's.

STS-the rear mounted turbo. I am building my own kit around a t-70 and 2 stages of nitrous. This places the turbo where our muffler goes. Their kit is pretty good, but you will hear I love it, or I hate it on all of this stuff. With this type setup, turbine housing and piping size is critical for good performance. It doesn't clutter the engine bay up at all, it sounds really unique. Look into it, there is a wealth of info on their website. The things I dont like about their kit is that you cant run a driver's side subframe connector because of how they ran the cold tubing, and the exhaust MUST be wrapped to try to maintain heat and velocity for good performance.

The point in twins is to use 2 smaller turbos to generate the airflow required while often providing a quicker boost response. Since the airflow is added, but the boost is not, 2 hybrid turbos can easily provide the airflow to support 800+hp, and to do this in a single something like a t-76 would be needed. But a properly sized single will be lighter, easier to fit, provide comparable power, be MUCH cheaper, and come very close to if not the same boost response.

[Injuneer]

What are your performance goals? The LS1 engine can produce very high HP without a blower or twin-turbos. Anything that put's enough boost into the engine is going to require a complete strengthening of the rotating assembly. Then the drivetrain will need major upgrades. Then the suspension, wheels and tires to put the power to the ground. You could be looking at anywhere from $5,000-$15,000. If that's your budget, you'll be OK.

A simple heads and cam upgrade can produce a good HP increase, as long as its spported with the required intake, exhaust and fuel system upgrades. Much more economical than getting into an expensive boost application.