Supercharger vs. Turbo

[2crunk]

I just wanted to get some ideas for the set-up on my car. What do you think.....should i get a superchager or a turbo? From the research i have done they will cost about the same. Also, i want to take into consideration, wear and tear on my motor, ie: a supercharger will be on all of the time, i haven't heard of alot of mustangs with turbos although i have sen a few. If anyone has experience with turbos on a V8, and would like to comment please do. Last thing, if you do recommend a turbo what brand, size, etc. should i consider. Thanx for the feedback.

P.S. if i did go turbo, would a single or twin turbo set-up be more efficient? Thanx again.

[duplox]

We need info! What motor, what are your power goals, etc. Have you driven a turbocharger and a supercharged car? What do you prefer? unless you're going for 100% track vehicle looking for max HP, this makes a big difference. A supercharger will simply make the engine 'feel' like a larger displacement engine... The torque/hp curves will be pretty much the same shape, just higher up. A turbo is completely different. Its more of a slight 'lag' before the turbos spool, and WHAM you're gone. I personally like turbos much better, I like the lag. Its fun for me. It entertains me to leave off idle so the guy next to you think he has you since they leap ahead off the line, then you whip past them 50 feet down the track. More dramatic than slowly pulling away . I am currently turbocharging the 351c in my 1969 mustang coupe, right now I'm building the motor to take 15psi boost. Should give me around 700ft/lbs of torque and 675-700hp at the flywheel, revving it to 6500rpm. The nice thing about turbos is, the torque curve should be pretty flat (on my engine, from 3000-6500).. Engine Analyzer(like desktop dyno but better, imho) predicts 697 peak torque at 4000rpm, 653tq at 3000, 627 at 5500.. From there the exhaust turbines on my turbos get a bit restrictive(when I bought them they were sized for 5500rpm not 6500), so torque drops to 544 at 6500. Thats where peak HP is made, 673hp. Someday I'll get better sized housings to get the top end up. A supercharger wouldn't be able to give ~650ft/lbs at 3000rpm, hell it'd barely be making boost at that point. The turbos are giving the full 15lbs by 3000rpm. If you have a 5.0L, I'd suggest two .42/.48 A/R Garrett T3's if you plan on revving it to 5500-6000.. If you go higher, look for a bigger exhaust turbine. I'm running .60/.63's on my 351c, and I think they'll be a tiny bit restrictive on the top end, not as much as EA predicts though. It should be completed in a few week, I'll be sure to put a post up on this forum of how it goes... I'll probably be heading to the dyno first thing after the motor is broken in.

[Cobra01TT]

Single is always more efficient.
Properly matched, a turbo will not have lag in the sense that you are thinking of. On a 1.6L Civic, maybe, but not on a V8. If you get a big ass turbo to make huge power, then you will. The Hot Rod arcticle on the subject pretty much declaired the turbo a complete winner.

I was planning on getting a Pro Turbo Kits setup with a T-66. It's really your choice on what brand, they're all good. For twins, I was going to go with a Indution Concepts setup, with two 60-1 Hi-Fi's. www.inductionconcepts.com is a good site to check out, with lots of info.

[duplox]

Why would single be more efficient? I'm not saying you're wrong, I'm just curious, as I've done more than considerable research on turbos, and have never heard one way or the other which is more efficient. If there is a difference, I would be willing to bet it'd be negligable, as in 5hp out of 500.
Any and all turbos will have 'lag'. All turbos require a certain ammount of exhaust flow to get it going, and unless you have a severely undersized turbo on your motor, it will be noticeable. It won't be nearly as noticeable as a 4banger, since a v8 won't have to rev as high to make power so you can size your turbos smaller. V8s will have gobs of torque down low anyways, so its not much of a sacrifice in the first place. Its not like on a 4cyl where at 2500rpm you're making 90ft/lbs, even N/A you can easily coax 300ft/lbs out by 2500rpm of a v8. But for both engines, the efficiency range of the turbo will be about the same... So if you take two similar designed turbos, one sized for a high revving 4banger, one sized for a high revvin v8, they'll provide boost in about the same range. I do know what your saying though.. I mean, if you have a manual or an auto with a decent stall(2500-3000) and if you size your turbo(s) properly, you can launch on full boost. I have a 3500stall in my mustang, so I could definately launch under full boost if I wanted to. But launching off idle or somewhere below your turbo's spool RPM could be beneficial - I've heard from many people running turbos that if they leave off idle, they'll run quicker, since they can launch without being in danger of breaking the tires loose, then a split second later boost kicks in while they're already moving. I suppose if boost hit very hard it could break the tires free after you're moving, but I can definately see how it'd be easier to control and be more consistent launching off idle.

[GMCSprint1971]

Hello,

I have a 1995 Stang with a 3.8L. I believe they make turbos for them. I heard the 6-bangers have crappy heads, wouldn't a turbo blow the lid off? Any thoughts?

[2crunk]

I have a 4.6L V8 GT, i am interested in increasing my "top speed" (i hate being passed by hyundai's and subaru's on the highway), but i would love to have excellent 1/4 mile potential. What do you suggest?

[stang_racer20]

Just about the only way to increase top speed and acceleration together is to increase horsepower. Using a lower gear ratio will increase acceleration but decrease top speed. Using a higher gear will increase top speed but will decrease acceleration. So you'll have to find an intermediate gear which gives both a little bit. Otherwise you can use a larger diameter tire which will also increase top speed, but once again you will loose some acceleration due to rotating mass. There's always a give and take situation, you cant get one thing without sacrifing another, lol.

[2crunk]

Yeah, thats kinda what i have been told by other people. Do you know if turbos take away from top end, or do they help both, 1/4 mile time and highway?

[Cobra01TT]

Your gears will determine "redline" top speed, but most Mustangs will start flying before that. I figure with the gearing on mine, I *could* get over 200mph, but there's no way my car could make even close to that.

I don't remember exactly why one turbo is more efficient, but I know that it is. Having two smaller turbos will however kill turbo lag, so they are good for the street, just way more expensive.

I would go with twins if I had the money, they're more like a roots s-charger. A big one is more like a centrfrugal s-charger. The differances are much smaller though.

Turbos add power, so they won't just take away from any thing. Acceleration will be helped, and top speed won't.

[duplox]

They won't add as much power at top end, but they'll still add a whole bunch. I mean, 544lb/ft at 6500rpm from a 355ci engine is still better than most engine builders could get n/a.. Sure is a hell of a lot more than I could get! I'd be damn pleased with 450lb/ft from that sized engine N/A. Like any compressor, they have a peak efficiency... at a certain point they'll work best, and at all other points they wont work as well. You could size your turbo to give purely top end power, but you'll have significantly more lag and less useable powerband. I sized mine so they kick in early and just start losing their oomph by redline.
A turbo or supercharger combined with lower ratio gears will give you a higher top speed. Just lower ratio gears will get you a higher top speed, but it'll hurt accelleration, and if your motor doesnt have the power in the first place, you wont go any faster. The top speed on my car should be around 150mph, but I'm sure if I put an O/D tranny or lower ratio gears in it, it'll go faster.

[mysvtpony]

1/4 mile = charger
long haul = turbo. there is something called a spoon controller to decrease the lag on turbos but maximum hp is compromised. also a charger i reckon is more beneficial because it is constant where as the turbo truly shines within cars with high compression motors (High RPM cars such as the honda s2000). Good Luck, either way ya gona have some really really crappy gas mileage.

[duplox]

Centrifugal type superchargers are the worst forced induction in my opinion. The only benefit to them is they're the most compact. If you want all out HP throughout the entire RPM range, a roots blower is the way to go. Thats more of a V8 thing though. For a driver, turbos are the way to go. they combine the efficiency of a centrifugal supercharger with reduced parasitic loss and the boost control of a wastegate to give full boost through much of the RPM range - not as wide of a range as a roots blower, but wide enough to cover the power band of most street motors. Roots blowers are the most inefficient design, however.. They take more hp to turn and heat the air charge more than centrifugal type.

[2crunk]

what do roots blowers run?

[duplox]

what do they run? as in boost? they'll run whatever you set them up to. They are a positive displacement compressor, which means every revolution, no matter how fast or slow, they'll move the same volume of air. So how much boost is a function of the displacement of the blower per revolution times the gear reduction of the drive of the blower, over the displacement of the motor per crank revolution. So basically, by changing the gearing on the blower you'll get whatever boost you want. The Cobra mustangs and Lightning trucks use whipple superchargers, which are similar to roots. They're also positive displacement. There are several types of positive displacement superchargers, pistons are a positive displacement compressor, vane type superchargers are positive displacement.. there are even Wankel style superchargers(rotary engines that are spun by another engine to compress air). Positive displacement types have no 'lag' whatsoever. Roots types aren't terribly efficient, some of the others are better choices. Whipple chargers are some of the best, and I believe vane types are also very good. Wankels are decent but no one makes them anymore(they were used long ago.. like 5 decades ago..) Piston types arent very efficient and arent practical. They're almost as big as a piston engine, so whats the point? I think Roots types are used in professional drag racing because they're simple and they move huge ammounts of air for their size. And considering how big they are, you get an idea of how much power these motors make! I'm not sure where you would get a roots or any other positive displacement type supercharger for a 4cyl, most superchargers, especially roots/whipple, are focused at the v8 market, while most turbos are focused at the 4cyl market. In my opinion, the situation is very backwards.. v8s should be sporting the turbos with their ability to provide big flat torque curves, plus v8s don't really need to worry about low end torque before the turbo spools, they've got that covered... And the 4cyl will really get a benefit out of a positive displacement type blower, since it'll provide boost at any RPM, so it'll give them a boost in low end torque, but still feed them way up at 7500, 8000, or whatever RPM they'll spin to. 8cyls don't need to rev that high to make their power, they're better suited staying around 6500, and thats perfect to take advantage of a turbo's efficiency... The 4cyl needs the RPMs to make its power, and a positive displacement supercharger will both boost its power up top, and help it out down low where it isnt so strong.
I suppose if you wanted a positive displacement for a small motor, you could buy a whipple charger and gear it down a bunch. I'm not sure if it'll work too well though. The ones for the mustang and Lightning are designed for 8psi on 5.4L, so you'd have to gear it down a LOT to get it to work on a 4cyl. It might not work, and if it does, it'd probably be pretty inefficient.

[2crunk]

Originally Posted by mysvtpony

1/4 mile = charger
long haul = turbo. there is something called a spoon controller to decrease the lag on turbos but maximum hp is compromised. also a charger i reckon is more beneficial because it is constant where as the turbo truly shines within cars with high compression motors (High RPM cars such as the honda s2000). Good Luck, either way ya gona have some really really crappy gas mileage.

I'm sure i will have crappy gas mileage, but if i was worried about gas mileage i would have bought a KIA. lol....But thanx for the info.