I have to disagree respectfully with nearly this entire post. If a turbo drops off after 5k rpm, there's someting wrong with it. Someone didn't change their valve springs and are getting float OR they are choking off a turbo that's too small (Like some STS guys do with their base turbo's when upping boost). ATI and Vortech, I love them, but they make peak boost at redline... come on... that's gonna beat a properly-sized turbo? I don't think so. There are alot of guys here making peak boost on turbo set-ups 500-900 in rwhp between 3000-4500 rwhp. It doesn't even come close.

https://ls1tech.com/forums/forced-induction/440545-short-video-my-stroker-turbo-setup.html

Dyno... http://img375.imageshack.us/img375/2...a125lbs9br.jpg

Check out this guy's dyno. This is a high HP application. I've seen alot more area under the curve in smaller set-ups. However, this guy's shooting for the stars and still beats a centri. SC.

Peak torque at the same, approximately, RPM as you... except for an ~800 rwtq figure.

...Just an example.

 

When you want to compare a Turbo to a SC you should try to get dyno graphs with similar peak HP and TQ number. I have compared my self few similar Turbo graphs against D-1SC's around 3500RPM and i found 7 out of 10 D-1SC cars are making more TQ at those levels. As i said in my post when a turbo is sized right for the job it will make more power, but will most likely lack in some other area. The SC might not make the most power in one area, but it will do everything well. No lag and no drop off in the powerband up top. When i say drop off up top i don't mean valve float... I mean turbo is sized to give great low end and midrange.

For comparison sake... If your car is making around 550rwhp post the link to the graph or the graph it self. If u remember a link that had a dyno graph for a turbo making around 500rwtq or so post that link too.

 

Search is not behaving for me right now. I know what you're saying about those that choke up top but have unbelievable low-end... those are turbo's that are too small. The 500 rwhp graph's I've seen that I've tried to mimic are 346's with T-70's and T-76's. The T-76GTS was on my eye for a while but with the T-70 I'll get some midrange, I'm guessing... peak boost at around 3500 rpm or lower (Not to lie, the GTS was too much for my motor. It should wait). I won't rev past 6 k rpm. and nothing will drop off. Like you said, it's all in the sizing... by that fact, properly sizing a turbo, as I said, will allow the builder to achieve peak boost between 3000-4500 rpm's (with no drop off!) on an engine at power level's of ~800 rwhp OR ~500 rwhp, which would even be easier to get more powerband with a ~500 rwhp number.

Bottom line, if you know what you're doing, there is NO drop-off. Yea, alot of STS guys maxing 60-1 turbo's over 425 rwhp, I could see getting this powerband flaw. However, that's not a universal quality... any more than all ATI's having belt problems would be a universal quality.

The advantages of SC will never be denied, as faster times will sometimes linger in the SC world more than in the turbo world. Creating power without load will always make throwing a SC'ed car into the quarter mile much easier, though with 2-steps people are making strides launching turbocharged LSX's.

A D-1 is a D-1. Many people are maxing out small turbo's and getting shitty powerbands up top. These are not good examples. Yeah, the turbo powerband is tricky considering cid vs. turbo sizes. Its easy to get either too much lag (high rpm boost) or boost drop-off (low-rpm boost with some choking at the end). It's not as easy as buying a SC, no doubt.

Your car is sweet and will take a great many cars here. I presume it will take mine. I'm assuming you have a hard-top/t-top car. I'm looking a at a ~480-500 rwhp number and I'm a big-*** heavy 'vert (3800+ lbs). I've made it a point, however, to achieve a very disreable powerband for highway pulls. I'd love to post a dyno. but as my sig reads, I'll have them soon while I get tuned.

 

Here we go, this is from an STS and a T-67.



Peak rwtq a touch over 4500 rpm, more rwtq than rwhp... now, look at the peak rwhp. A centrifugal SC will never have it that low. In addition, this is on an STS which are known to have more lag (most of the time) than a front-mount. A front mount will peak the torque EVEN lower with a similar turbo... probably 4000 rpm. This is what happens when you get peak boost at an rpm other than redline. I don't see any drop-off. PLUS, look at the torque's drop-off, almost negligible when cross-referenced with your torque curve.

Now, this is my point. This is an STS. Think of a front-mount PLUS TWIN TURBO like somebody suggested, which I said for F-body's is not easy (thought two kits are in development by Hi-Flo and GMR). Think peak boost at 2500-3500 rpm. on a LSX IF NOT lower. There is NO WAY that a Twin set-up will peak higher than a centrifugal SC like someone suggested. That's ridiculous. This is what my point was. Only a Roots/Twin Screw SC will get a curve like that to compete.

Correct me if I'm wrong. I'm half-asleep.

 

I don't know whats the combo on that setup, but it is a good power curve. Even though it is making 60rwhp more and 127rwtq more than the D-1SC graph im going to compare it to, it still drive the point i was trying to make about Turbos. Comparing that graph with this one http://www.msnusers.com/CarsRelatedG...oto&PhotoID=60
You can see around 50rwhp and 100rwtq more from the D-1SC between 3000-3500RPM where most people would think a Turbos advantage.

I have seen alot of dyno graphs like this from smaller and larger turbos that led me to the conclusion which is Turbos can be alot stronger when they are made for a specefit application (Drag, Street, RoadCourse, AutoX, etc...) while SC can perform well in all of these applications with no modification to the head unit assuming it was a D-1SC. Thinkin about it... even when you want to upgrade a forged engine that needs more boost u will end with a turbo swap to supply the extra boost needed.

Don't get me wrong i love turbos, but it is not for everyone. I have a TTi Race kit in my plan for my car anyways when i make it a pure drag car later on with a TH350-400 tranny.

Just my opinion and everyone could make their own conclusions

 

A front mount Turbos' usually is going to spool faster and more efficient than a STS, but the same rules apply.

 

Yes, and with twins? That was what my original point was.

I think...

 

wow a lot of great knowledge here!! could it be that you could find a case in both arguments. for example, you can find dyno comparisons showing that the blower makes power lower than a turbo set up, and you can also find comparisons showing the opposite.

 

Agreed.

Yeah, but no way... not on God's green earth, will a centrifugal SC have more area under the curve over a front-mounted Twin Turbo set-up with reasonably sized turbo's, both at the same power levels. Full boost at 2500-3000 rpms vs. redline. I cannot see it any other way, I'm sorry.

 

heres A DEE O's twin turbo graph. notice this torque curve

 

Ahh guys this is never ending. Again I'm not going to change your mind and you are not going to change my mind and we can let people decide their own. I think im done debating this point after this post.

Check this graph which was posted yesterday by Maddboost and compare it to the A DEE O's one posted above. These two graphs has smiliar peak TQ numbers, but you can see how the SC is making almost 200rwtq at 3K if not more and 100rwtq by 3800RPM and it kept a TQ adv until 4300RPM (where Turbo or Twin Turbo or STS charged cars shine in the midrange) or so and it keep above 600rwtq until redline while the TwinTurbo drops after 5800RPM. Dont get me wrong that is a good Turbocharged Graph and i dont think i would want the turbos to be sized any differently. It gave great low end for a turbo, midrange and topend.

As i said above 7 out 10 dynos u will find that a Centri SC will make more low end power than a Turbo. Again low end is under 4K and midrange is where the turbo picks things up and that is why they usually have a better area under the curve in some cases especially in the HP department. SC's usually dont pick up HP under the curve like a Turbo.

 

You can debate merits of each all day long, but if you really want proof of which power adder people prefer, look at how many people are switching from SC's to turbo's. There are none on this board, that I know of, that are going from turbo's to SC's.

Just ask for opinions of people who have had both ( ie frcefed98, NA$TY-TA, PurEvl ect ect)

Later,
Dave

 

People switching to a new FI system is not proof others can based their selection on.... what is proof is dyno sheets and some say track times giving similar conditions and setups. Im not saying this one is better than the other one.... I was just just clearning up a misconception about Centri SC and low end power thats all.

 

I understand that. I agree with you about the misconceptions about centri SC's and low-end torque.

However, dyno sheets as proof, do you think (between two equal level, ~500 rwhp, one Twin Turbo and one Centrifugal SC) that a centrifugal blower will peak its torque before a front mount twin turbo? Come on...

Horsepower is a function torque. Why do you think centrifugal blower cars usually have a higher hp number than a torque number? It ain't because of the impressive low end, that's obvious. That's why some 4g63's, for instance, make like 950 rwhp but only 500 or so rwtq... Power there is on the top end. I have yet to read an LS1 single turbo front mout dyno sheet, much LESS Twin, that will have more rwhp than rwtq. One PTK owner here has 480 rwhp or so and like over 570 rwtq (with a SINGLE on an LS1). That's torque on the LOW end.

 

I wasn't talking about peak. I was talking about area under the curve below 4K RPM. I said it more than once that Turbos have better midrange than SC's and their peak TQ and HP is achieved before a Centri SC, but in the midrange and not low end. Thats all. lol

 

Synergy has a completely stock Z06 with an STS Twin kit
with only 5 PSI, 505 rwhp/500 Torque thru the custom mufflers on the first tune.

Get this 400 lbs. ft. at 2,500 rpm. No lag. Torque looks like an EKG chart.

7 PSI. soon and great tune 570/570-600/600.

All their kits will be CARB legal shortly.

 

Very nice... When does the HP/TQ drop... 5600-5800RPM? Do u have a link to the dyno sheet?

 

The question posed by the guy who started this tread is whether or not turbos are a better power adder than SC's and the answer is YES!!! Now again you can discuss reliability, cost and company support but when it boils down to it, turbos make power more efficiently period!!! And I think the people who have had both and have personal experience with both, can give better advice than others who have not.

Most people on this board are not trying to down grade their set-ups, so one can conclude that the turbo set-ups are an UPGRADE from the super chargers these guys were running. Now as far as ease of installation, cost and all the other things there are to compare, it all just depends what the guy with the car wants to do. Just so you know, if you drive cars with similar mods and peak hp, the only difference being the power adder, ie turbo or a SC, the choice will be simple.

 

Couldnt have said it any better.

 

As I said before.... You can't really say Turbos are better than a SC or a SC is better than a turbo. Everyone has its adv and disadv. You can't also assume that Turbos is an Upgrade to SC owners. I have owned Turbo/SC and Nitrous cars before so I know how each of these setups react and work. As you said it all depends on what the guy wants to do, but my only main reason I replied to this thread was the misconception about SC low end power and TQ and that’s it.
I said SC does it better because it cover all the areas well while a turbo should be geared or chosen for what you want. Example, low end grunt turbo will lose somewhere else and the same goes for topend power while midrange always stay better than a SC.
I think this is going no where because I’m having to repeat my self in every reply. This is one of the topics that can go for 100 pages+ and I’m really not willing to take it that far. If u think Turbos are better in all areas with a unlimited adv then good for u, but everyone is entitled to his/her own opinion at the end.