Increased displacement vs. forced induction

[55 Hotie]

And Edmond, how did you get my picture to use for your avatar ?????

 

[Edmond]

And Edmond, how did you get my picture to use for your avatar ?????

I went to your house and took the picture!:L :L :L

 

[Vettelt193]

This debate is also driven by money.... the ultimate question is, how much do you want to spend, and how much power do you want? A side factor is gas mileage and drivability....

If all you want is an extra 100 HP, and the same drivability and gas mileage, then just supercharge or go with Nitros.

If you are looking for more than 100 out of your L98, then you will need to look into 383 for 'safer' power increases. But, with a 383 comes lower gas mileage....

IMO, It would be cost in-effective to build a mild 383 and add a mild supercharger. superchargers aren't cheap, and re-builds or new engine builds aren't either. When you factor in time (either your own or a mechanics) you realize it takes the same amount of time to build a fairly wild setup 383 as it does a mild 383. The cost of parts doesn't go up that much either, from a mild to 'fairly' wild 383. Also, the price of a supercharger won't change much, if at all, from mild boost to big boost. So, while a mild 383 with mild supercharger will yeild very reliable results, with fairly good gas mileage, you will pay a fortune to get that set-up.... this is why most people with 383's just have a pretty wild 383, with no blower, or they wind up keeping the engine closer to stock with bigger boost.

 

[Monty]

i believe you would have less plumbing with a super charger and a more flat torque curve because it is is always pumping and less under hood heat . the turbo needs to spin up before hp increases start lots of plumbing lots of extra heat.

Sorry, but you have that reversed - turbos produce far more torque than a supercharger (centrifugal). Since a turbo is not rpm dependant like a supercharger, but rather load dependant, it builds boost based more on throttle position. A properly sized turbo can produce boost by 2500rpms or so depending on the turbine, and maintain that boost throughout the rpm range. Of course it's going to be more efficient at some point within that range and less efficient at others. Conversely, a supercharger typically doesn't start to produce maximum boost until 80-90% of engine redline. As a result, the turbo will have a far superior torque curve and have much more area under the curve.

 

[bradfordsvettes]

----------Turbo vs. Supercharger


http://www.superchargersonline.com/techarticles_detail.asp?RecordID=13


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While the supercharger is generally considered to be a better method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. Superchargers generally provide a much broader powerband that most drivers are looking for with no "turbo lag". In addition, they are much easier to install and tune, making them more practical for a home or novice mechanic. this was off their site This is a great site superchargersonline .com much more info there. I was not saying a supercharger makes more power it is just the power curve is more flat and even with out turbo lag . I have driven and worked on both and they each have their benifits the super charger is better on the street i feel but nothing like the feel of the turbo spooling up it is neck snapping ,but the supercharger feels much the same all the way from idle till when you step on the go pedal so I still think my post was correct Steve

 

[bradfordsvettes]

monty is that enine in your car now sounds awsome they all sound scary when doing a pull makes me cringe :eek :J Steve

 

[Bullitt]

Talking about Street Motors

Buliding a wild small-block would in all likely-hood have most people looking for more compression to use on pump gas. This would be in direct contrast with what a turbo or supercharged engine's require, which is lower compression. Basically, without getting too technical, the lower the compression (stay above 7.75) the more power either one of the forced systems can make. For superchargers, discounting highly specialized needs, the optimum should be around a 8.5:1 ratio. However, for reliabiltiy's sake, forged pistons are highly recommended. Basically, for any stout engine, you want a beefy bottom-end. Superchargers and turbos demand it! And you still have to use quality fuel.

Once I get back home, unless circumstances change, my mind has been made to build my engine in preparation for a Pro-Charger supercharger. After talking with a few racers that are currently using their system, I'm convinced that not only is it a good product, but it's priced just right. My main problem will be hood clearance, but I have seen a '66 Stingray outifitted with one, albeit with a Grand Sport hood.

I know of no company that makes a competitively priced turbo system for my big-block and would let me retain my side-pipes. I'm sure I could modify a system if I wanted to, but want to finish my "engine stage" in a timely manner.

--Bullitt

--Bullitt

 

[Monty]

----------Turbo vs. Supercharger

While the supercharger is generally considered to be a better method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. Superchargers generally provide a much broader powerband that most drivers are looking for with no "turbo lag". In addition, they are much easier to install and tune, making them more practical for a home or novice mechanic. this was off their site This is a great site superchargersonline .com much more info there. I was not saying a supercharger makes more power it is just the power curve is more flat and even with out turbo lag . I have driven and worked on both and they each have their benifits the super charger is better on the street i feel but nothing like the feel of the turbo spooling up it is neck snapping ,but the supercharger feels much the same all the way from idle till when you step on the go pedal so I still think my post was correct Steve

I've also owned and driven both custom turbo cars as well as centrifugally supercharged cars, and to say the supercharger is generally considered to be a better method of forced induction for most street and race vehicles is biased, misleading, and blatently untrue. You have to look no further than what the OEM's actually produce to see that turbo's are overwhelmingly favored for street cars . Nearly all of the world's elite cars use turbocharging if they utilize forced induction - Porsche, Ferrarri, Lamborghini, etc. Even the mainstream OEM's are offering and favoring more turbo equipped cars - such as the PT Cruiser, VW Beetle, plus numerous Asian imported cars. Considering that an OEM's primary concerns are ease of drivability, cost, minimal warrenty claims, 100K mile warrenty's etc it's obvious why they chose turbo's over superchargers.

As far as racing is concerned, where turbo's are allowed they out number and outperform superchargers. Look at the NMCA/NSCA and NMRA classes that allow turbos, the supercharger guys and nitrous guys have either switched to turbos or they are whining that the turbo guys have an unfair advantage. As a result, the turbo equipped cars are required to run at a higher weigh in and they are also limited to smaller engine displacments to provide a level field so that the supercharger and nitrous guys can compete. Not only do the turbos outperform the supercharged and notrous cars, they are generally more reliable. Some turbo racers even claim to have competed the entire season without even removing the valvecovers. That's probably an exaggeration, but the fact is that the turbo engines are more reliable.

Before anyone mentions Top Fuel or Funny car as evidence of superchargers superiority over turbo's, remember that turbo's are banned by NHRA as a means of slowing the cars down and reducing the cost of racing. In Top Fuel and Funny car, it's not a matter of power, it's a matter of traction and clutch management. When the cars are already making 6000+hp and running 300+ mph, what would the incentive be for them to add a more efficient power adder so they can make more power. NHRA is trying to slow the Top Fuel/funny Carscars down, not make them faster. Plus, the fans expect to see flames and thunderous nosie when the cars race. Even if turbos would make the cars faster, the NHRA figures that fans would n't like them as much because the cars would be significantly quieter and less dramatic. While it is impressive that those guys are making 6000+ hp from a 500ci engine, or 12+hp/ci. Even more impressive was the fact that the 80's Champ cars were making over 1300hp with only 90ci, or almost 15hp/ci. Unfortunately, the turbo's were again banned in an effort to slow the cars down and reduce racing costs.

To say a centrifugal supercharger provides a broader power band is misleading and untrue as it depends on the turbo size and design. Sicne a turbo is load dependent, rather than rom dependent like a supercharger, a properly sized turbo(s) will spool up and provide significant boost (torque)at a relatively low rpm, and be able to maintain that boost throughout the rpm range. For instance, my engine makes over 700ft lbs by 3000 rpm and maintains that to over 7000rpm, peaking at almost 1000 ft lbs at 5100rpm on 93 octane pump gas. Conversely, most superchargers are designed to provide maximum boost at about 90% of the engine's redline. That same supercharger may not even be produce boost at 3000rpm, if it does, it's probably only 2-4 lbs.

Turbo lag is an overblown issue, especially on a street car with an appropriate converter stall (if it's an auto). With the turbo's available today, there is no reason that a V8 engine would ever have any noticeable or significant turbo lag. Unfortunately, most people hear about turbo lag and it gets blown out of porportion, or their only exposure to turbo engine's is through some small displacement import, Buick GN's, or some other domestic turbo that was built during the 70's and 80's. A V8 engine provides plenty of exhaust energy to spool up a properly sized turbo. Actually, in some cases some lag is desirable because it doesn't tend to overwhelm the tires as bad. With the 3200rpm converter I have, the engine is already making boost by the time the converter flashes and the car starts to move forward. Too much throttle too quickly and the tires light up - a little lag would make it a little easier to drive.


I also don't know where this myth that turbo engine's are hard to tune started - probably by people who don't know what they are doing. After I assembled and built my engine and turbo system, I took it to get dyno'd. Not only did the engine crank, and run on the first attempt, but on the very first dyno pull with no tuning other than setting basic parameters, the engine made over 1000 hp and 900ft lbs. Within 4 dyno pulls the engine was tuned and made over 1200hp/1000tqon 93 octane. It took less than 2 hours to tune the engine for maximum torque and horsepower, while it idles smoothly at 850 rpm. When I got the engine installed in the car and running, it took me about 30 minutes to tune the cold start enrichment, and TPS/MAP enrichments. That's less than 2.5 -3 hrs of tuning - hardly what anyone would consider difficult ot tune.

The only real advantage a supercharger has over a turbo, is that in most cases superchargers are easier and cheaper to install. Hwne cost and ease of installation are the primary concerns, go with a sueprcharger. If performance and relaibility are the primary concerns, go with turbos.

 

[bradfordsvettes]

That was my point that for the average person with a basicly stock car the supercharger is a pretty good bang for the buck .Plus there is not much of a need for a converter change unless your looking for a stall speed change. I am not knocking turbos at all but there is more work involved and cost. what is your opinion of the under hood heat issue .Obviously you have much more expetise in this field than I do.I am just your every day auto tech{ aka grease monkey}. It was just an opinion as to what would be the easiest conversion for a street car with a good seat of the pants feel .How does your car hook up with that power must be awsome. TURBOS FOREVER Steve

 

[sothpaw]

keep it simple

Edmond,

Nitrous would be the cheapest way to get what you want, and
it's probably just as safe if done right. What I don't like is that
if your NOS installer does it wrong, you WILL blow the engine if you ever get a lean condition. And don't come crying to the NOS installer...

Supercharging: Good if you want 100hp, but won't help if you only
want to pay for 30-40. Plus, you're depending on some manufacturer to make a quality product. I've heard of belts slipping, etc, car is always in the shop. Do you really think if
the supercharge manu. sells a 1000 units a year and mostly to
racers that this thing is going to last 100k mi? Big auto companies
have so much more money to put emphasis on quality.

383: The simplist. Modify what GM made. Drill, hone. I think it will
have to be more reliable. Plus, if you only want 40hp, you don't
have to go full bore, so to speak.

 

[Edmond]

The 383 would be a project that I could do slowly right? I could get the motor punched .030 over with some nice flat top pistons. That would change my compresson ratio right?

If my compression ratio changes, I should get my custom chip reprogrammed right?

Then I should port and polish the heads, get headers and so on right?

Are most projects like this done over time or pretty much done at once?

 

[JRMaroon]

It Looks Stock

My Cubic Inches vote was for the simple fact that I am the only one who knows what I'm running. Forced induction is awesome but how cool is it to have a stock looking car with nothing more than an intimidating exhaust note to tip your hand? People will be more curious about the car if they can't tell what makes all that TORQUE.

Jeff

 

[KANE]

Can you guys give me the benefits and downfalls of each?

Which is safer?

Cheaper?

More efficient?

Easier to do?

Given the choice, which would you do?

If you are looking to add some umph to your 88... I'd suggest a Powerdyne supercharger. TPI responds well to forced induction (example: Callaways).

I'd like to supercharge my L82/TPI set up. But, that costs $$$ and I think I'll wait a few years until I'm so bored I contemplate selling it that way it feels like a new car when I get done!
:L