I agree. It is very hard to spin a centrifugal over about 60,000 rpm due to belt drive limitations. This is definitely to the turbo's advantage, as it will spin as fast as the exhaust will push it. Plus, the turbo compressor impeller is designed different (blade angles, curvature, and volute taper) to be efficient at these higher speeds. But. . .at my boost and hp level, the turbo should be spinning in the 60 - 65,000 rpm range, when I was running the T-trim in the 50,000 range. This is to create the same boost pressure since, while efficient at higher speeds, you have to spin the turbo faster.

 

Mike,

This is the test I've been waiting for!! I don't have the cash to do it myself, but I'm glad that someone with an engineering background, and a relatively unbiased opinion is doing this experiment.

I'm gonna go out on a limb here...............................

Obviously the turbo will eat the centifugal's lunch in terms of average torque and horsepower, but.........................

I think the T-trim will make slightly higher peak HP.

C'mon, someone's gotta vote for the underdog!

Raymond

 

I'm not really sure why most people think that the turbo will make less HP. I personally think that it will make more HP as well as torque. I don't expect that a T76 will run out of steam at 6000-6500rpm where the redline will likely be set, and we all know that the turbo is the way to go for efficiency. The blower is using the most HP at the RPM peak so I really think the turbo will make more power up top. I say at least 20rwhp more at the same boost level and definitely more torque through the midrange when it comes up on boost. Just my $.02.

 

I've heard that turbo's are typically more mechanically efficient, so assuming this is true, a turbo could make more power at the same boost level, but you have to also take adiabatic efficiency into account. I have no doubt in my mind that today's turbo's have VERY efficient impeller designs when it comes to adiabatic and mechanical efficiency (and volumetric efficiency due to there high RPM capability), but you still have exhaust flowing through a turbo. This has to affect intake air temp in a negative way. This is the only reason I think there's a slight possiblilty that the centrifugal "might" make just a tad more "peak" horsepower.

I'm no expert. I'm not an engineer. I could very well be wrong. I wouldn't be surprised at all if the turbo comes out ahead across the board. Saying that I think the centrifugal will make more peak power is just a guess. It's all in good fun.

Raymond

 

I think alot of people are guessing a slight to nil increase in horsepower but I disagree. One thing that separates turbos and blowers is the intercooler. I Think air to waters are great and can be awesome on the dyno. air to air just doesnt get it done on the dyno and since he is using the aftercooler he is gonna make more power cause his IAT's will be lower than before because the turbo is more effecient.

Dont misunderstand what I said about air to air, it is good on the street but doesn't do much standing still, even with a fan.

I hope you have a cowl hood to let all that hot air out from that exhaust piping.

I'd also recommend the bigger watertank for the aftercooler if you dont have one, mine and a few others have the one gallon mounted in the battery location. My IAT's where in the 110-115 range with about 12psi. It was about 60-65* ambient.

 

I have a 5 gallon plastic water tank in the trunk. I've checked the water temp after 3 dyno pulls in the past and found it to be barely warm.

Mike

 

Nice, I almost went there but didn't. I didn't want to run rubber hoses under the car or swiss cheeese the firewall. My guess is 30hp once you get your tune down.

 

I think a PT Garrett 76mm turbo is capable of making more power than a T-Trim. Harry at PTE compared 76-78mm stuff more to YSi-Trims to me on the phone a while back.

 

How much bigger externally is the YSi to a S-trim. I have not been about to see my friends mounted to his big block yet. I am thinking about skipping the T Trim altogether,

 

You can mount the YSi with the standard S/T-Trim brackets and a little modifying, but Chris Sikora makes a sweet setup as well that's optimal. Only problem is that Chris' requires a very standardized set of parts to go along with it. Luckily my combo already correlated with what was needed.

If the engine can take it, just skip the T-trim if you are able to. Very good blower as well, had one for years, but pulley down the YSi and you have loads of room to grow.

 

I think this is a big point here. We aren't really comparing apples to apples due to the different size and style of the compressors. If we dynoed a T-trim and a YS-trim you'd see a difference just from the efficencies of the two compressors. Its really hard to change only one variable at a time.

But all that aside I'm voting for the turbo to make more power. The system efficiency is greater and the compressor efficency is greater. We'll see if the heat plays a part in it.

 

Ok, so tomorrow's the big day. For the sake of record keeping, I've put together everyone's guesses. A bunch of people weasled out with a qualitative guess, as follows:

Sean94Z: “slightly more”
BlkLt1Z28: “partial to turbos”
JordanMusser: “a lot higher AVERAGE power”
CamaroSSGuy2: “really close”
‘68Lt1Camaro: "slightly less", "more average"

Some people, though, layed 'em on the table and gave quantitative guesses:

GeoffChadwick: +12 hp, +20 ftlb
RealQuick: +/- 5 hp, +40 ftlb
Fstenuf: +7 hp, +65 ftlb
Turbo6: +20 hp, more torque
Flip94TA: +30 hp
Highlander: +23 hp
Me: -10 hp, +100 ftlb (though I have the advantage of driving the car)

If everything goes as planned, I'll post the results tomorrow.

BTW, the old set up made 547 rwhp at 6500 rpm and 571 ftlb 3700 rpm.

Mike

 

my guess... turbo will have a nicer dyno chart... more power more torque .. more average... on the street... from a roll 100-150... i say supercharger wins

 

You know, now that i think about it...Most people have said a 700 hp turbo car vs a 700 hp s/c car, the turbo car will dominate, all other things being equal. The reasoning is "the area under the curve"
Well when you race, what rpm are you at? I know i drop about a grand or so every shift, so that leaves me in the 5800-6900 range the whole time...AKA my sweet spot....so the 2-5 rpm area never comes into play.

you may ask "what about off the line??" If anyone here can harness 400 hp of the line, much less 700 hp on street tire, your da bomb. I cant.
In fact, i love the progressive and consistent feel of my supercharger. It still take alot of work to not lite up the tires, but its consistent and i can figure it out.

THis is just my thoughts, im not saying a s/c is better them a turbo or visa versa. Im happy with it, and thats what is important.




lastly i will change my "really close" too 539/595

 

my guess...
45 - 60 more hp
and 125 - 160 more tq

santore