After seeing everyone bicker over which is better, turbochargers or superchargers, I've decided to find out for myself.

I've shown thermodynamically, that a turbocharger should make ~15 hp more than a supercharger, boost for boost, due to the more efficient drive mechanism. However, MM&FF's test on the '03 Cobra motor showed more like 80 hp in favor of the turbo. BUT. . . I've seen other tests with the supercharger in the lead, albeit by only 15 hp.

So here I am, trying to prove which will make more power.

My old setup was an 8.3/1 383, AFR210RR heads, high lift 224/236 - 114, 0 adv, ported LT4 intake, Hooker LT's, Vortech T-trim (13 psi peak), and Vortech aftercooler. Through a TH-350 with a loose converter, it dyno'd 575 rwftlb and 550 rwhp and ran 10.40 at 133 mph in a 3800 lb pig.

I just got done with the new setup: EVERYTHING'S THE SAME, except the type of forced induction. I built my own turbo set-up, which incorporates 1 3/4" primaries, a 2 1/2" crossover pipe, 3" up pipe, and 3" downpipe connecting to the existing cat-back. The inlet to the compressor is 5", compressor to intercooler is 3", and intercooler to TB is 2 1/2". I'm still using the Vortech aftercooler to insure there are no inherent advantages to a different intercooler or piping. The turbo is a Precisions PT-76 GTS and the wastegate is a Tial 40 mm. Boost is set at 12.5 psi since the supercharger was making 12.5 psi at peak hp.

I got it running last weekend and drove it around a bit last night. My first impression is that there's alot more mid-range torque due to 12.5 psi at 3000 rpm rather than only 6 psi from the T-trim. Turbo lag is not as bad as I expected and the exhaust is much quieter now.

I'll get it on the dyno in the next couple of weeks. It should be interesting. Anyone care to guess how much difference there will be, and which will be the victor?

Mike

 

I think the turbo should make slightly more horsepower than the supercharger because you dont have the supercharger's parasitic loss from being attached to the crank. I also think the turbo will be faster in general because of the boost kicking in sooner. The area under the curve will be larger with the turbo, hence the car will be faster. The only problem you could run into with the turbo is the need to pull more timing back because of the heat soak.

--Sean

 

Turbo>Superchargers In the OOOOO AHHHHH Dept.

Supercharger>Turbos Ease of install and availabiltiy of kits

Turbo=Superchargers Both make great sounds

As far as which to make more power, I am partial to turbos, just look@ my sig

 

I demand pictures as proof.

 

AVERAGE hp is going to be a lot higher. what turbo?

 

I'm using a PT-76 GTS.

http://www.2weird.com/mike/pic1 mod.jpg

http://www.2weird.com/mike/pic5 mod.jpg

 

Do you still have the blower cam in there? If so that wont work nearly as well with a turbo as it will w/ your t-trim
-Mark

 

I don't think that's necessarily true. People, in general, can't decide what is a good turbo cam. I've heard anywhere from:
200/234 - 126 LSA, to
224/224 - 114 LSA, to
224/218 - 118 LSA, to
214/224 - 112 LSA, to
etc. . .
as being good turbo cams. So which is it? If we don't even know what a good turbo cam is, then how am I supposed to know what is a "fair" cam for this comparison?

Mike

 

Peak HP with be simular IMO...
THe superchagers are less eficient then turbos, due to no parasitic gear drag yes. But people commonly say turbos are free HP, taking no power to run. this is totally false, they take alot of power to run, Theres no such thing as 100% effeciancy.

Basically what im saying is in terms of power used to create more HP (very arbitrary numbers here) a s/c might might be 30% effiecint while a turbo is 40%.

That will make a 15 to 30 HP difference in peak, BUT you have to remeber S/c cars can runn better exhaust... i.e. longtubes witch i picked up 28hp from when my car was stock! So peak will be really close.

Now, i do agree, a turbo car done right will make more power under the curve then a S/C car, thus it will most likelty will be faster over all.

 

turbo cams typically have an equal duration, or more intake duration. the smaller exhaust duration helps keep exhaust velocity high. more exhaust energy = more power. (atleast thats what ive read)
just look at cams that the high hp turbo buick guys or supra guys use, they are almost always equal duration.
proof is in the results....all you have to do is browse through the list of sub 9-10second turbo cars, and i didnt see any with a larger exhaust duration.
blowers on the other hand favor a higher exhaust duration.
so already the test leans in favor of the blower.

also, a log manifold is the least optimal header design for turbo. although it is capable of making decent power, it has been proven as being the biggest bottleneck for a turbo system.


so overall, your experiment is a fun comparison, but it in no way will be a fair comparison for actually telling with is better, because turbo setup really is not optimal.


as for similar comparisons ive seen in mags/forums.........usually the blower can make highest PEAK hp, but turbo makes more PEAK torque and average hp throughout the rpm band, which theoretically makes it faster down the track with all other variables the same.

 

Holy crap, man! Can you at least let me get the results before trivializing my test by whining about how it's not fair. Usually people wait until the result doesn't come out how they wanted before doing that.

That's total BS. More velocity arount the head of the valve DOES NOT translate into more energy at the turbine wheel.

Not true, either. As I was saying, even in the turbo buick world, they use many different cams. The stock buick cam is 192/196 - 107 LSA (GASP! A 107 LSA turbo cam? Couldn't be!). Common upgrades are 204/214 - 114 LSA (but isn't that a supercharger cam?), 210/210 - 114 LSA, and 210/205 - 114 LSA. Once again, no pattern as to "what IS a good turbo cam."

Ya' didn't look very hard, then. INTMD8's old single turbo setup was run with a couple of different cams. How about these 2 for comparison:
226/218 - 117 LSA, which made 722 rwhp
214/222 - 114 LSA, which made 724 rwhp
all at 21 psi boost.

Wait a second! Isn't that second cam a supercharger cam with more exhaust duration than intake? That'll never work!

Just because there are alot of fast cars running more intake than exhaust duration, doesn't mean it's better. They could be fast because of the cam, or they could be fast in spite of the cam.

True, my driver's side header could be better, I don't think it's hurting it that bad. Someone recently made ~1100 hp with a 6.0 liter LS1 with twin turbos through the STOCK cast iron manifolds. Also, if you look at my pictures closely, you'll see that cylinders 3, 5, and 7 all merge into the 3" log, rather than "T" into it. Cylinder #1 is the only one that I wasn't happy with, but I don't think it'll affect overall output that much.

Mike

 

Hello, friend. I'm anxious to hear your dyno results. One thing to consider..... turbos usually don't fare too well on 'DynoJet' dynos. This type of dyno doesn't load the engine the way that it is on the street. Good luck!

-PS- I think you should just trade the old rattle-trap for my '89 TTA.

 

Subscribing to the thread... I want to see what the outcome is.. I have a T-Trim on my car.. Im going to be running 20PSi with methanol injection.. Ill get that dynoed sometime in the end of march or so.. but for now, I put down 520rw through the stock bypass on 10-9psi and 498 rwtq.. Stock bypass as in it was leaking. I since have upgraded to a turbo XS bypass and a smaller pulley currently seeing 14-15psi.. pulls much harder.. for somereason though it falls down at 4K rpm till about 5200 then picks back up and the a/f ratio drops below 10.0 and then back up to 11.8. Think it may be the coil or the gap of the plugs. But this should be interesting to see what it puts down with the turbo vs the SC.. Nice work on the turbo setup by the way.

 

There was a test in hot rod with a roots type,centrifical and turbo.All at like same boost level to keep the test equal.What the test showed was bascially what is common knowledge.The turbo cars will obviously have a much bigger area under the curve since they come into full boost way way lower than a centrifical.The centrifical gains boost as rpm increase.Centrificals can sometimes show more peak power than turbos but area under the curve no way hose.They can also help make the car a bit more streetable or make it a bit easier to hook up as they don't put out full boost at such low rpms.
The roots type blowers put out full boost much lower down in the rpm range and have instant boost response pretty much.Still in most applications the turbo will still outperform it in terms of both hp and torque production.

Also it is a big mistake to think 10psi is 10 psi.My little talon turbo at 18 psi is slower than my new big garette at 10psi.Airflow and efficiency are too reasons why.You can assume that upping the boost on the same power adder will produce more power up to the point where you start pumping too much hot air and some units can only put out so much boost.

It all depends on what you want to do.Around town and all around driving roots or screw types work very well.You get power low in the power band,strong boost thru the mid with a bit of fall over in the higher rpms.
Centrificals keep the car a bit more controllable and still can make great track numbers when you can keep the cars rpms up.They aren't as good in roll on situations but you can downshift to help them out.You can do this on turbo cars to.
Turbo cars can make huge power and huge torque but you start to sacrifice some lag time as you go bigger and bigger.Again you can help this out with downshifting if you are in the higher gears.Lag and spool time can be leasons with various things like the new ball bearing turbos or going to bigger displacement and stroker motors.

 

Wouldn't it be more about valve events, than actuall duration. Also the fact that to get a true "turbo" grind you would have to measure back pressure before and after, along with primarty size , head flow (especially exhaust side) , and the particular turbo etc?