Top Sportsman Turbo vs procharger?
 

I am knuckling back down on finishing my 70 gto top sportsman car and i am at the point to where I need to make a decision. 6 second ets are a must, but remember, we are still bracket racing. Curt geise has proven it can be done with a turbo, and big numbers. I'm not much of a boost guru. As a matter of fact, if you can't put a fuel jet, and a nitrous jet in it, I haven't done it. My biggest concern with a turbo car is staging and et consistency. I haven't really seen a similar style setup with a procharger yet, so I'm up in the air on both sides. Does anyone have any educated thoughts or opinions.

Race only
2600-2700#

I have a friend that has been running a hemi with a procharger for 4-5 years. I think he has been around 6.50s at best lately. He has broke a LOT of parts along the way, cranks, blocks, rods... you name it. He has used only new and top notch parts.

You try and go that route with a Pontiac and I think you will break most everything you can break. And you will have a hard time getting into the sixes at all.

Staging a turbo car (with a auto) is not a big problem these days. Getting the right converter is the big problem and that will take some time to solve.
Consistent ets will come when your combo i sorted out just like any combo.
If consistency is important I would go EFI and turbo and alcohol for fuel.

Thank you

Give Travis Quillen a call before you make a final decision. 256-476-1053. He is doing big things with Pro Charger and mechanical injection. If you are a jet man, it might be the way to go.

Sixes at 2700 lb is going to take 2000 hp. Depending on cubic inches and head selection, you should be able to get there with either power adder.

If I go this route, i will be starting clean slate. I've always heard the turbos are much easier on parts, but are harder to tune and apply to the ground. I'm completely open minded at this point.

If I can't find a feasible way that I'm comfortable with , I'll build a n/a motor and go bracket racing.

either or
 

Jr runs into the mids 6's with his F-3 procharged Grand prix. 522 Checy combo. car is very consistant. Im finishing up my Vortech car here soon. Chassis is good to 7.5 atm but the motor combo is capable of makeing over 2000 HP. Just car wont handle that much atm. There are a bunch of turbo cars that run with the WiseGuys that are 6 sec. cars but they do seem to either have a good run or and abort run, seems they alittle harder to drive. But guess its all in the set up

Here's some additional thoughts....

The power is going to be vastly easier to make with a turbocharged powerplant. Also, it will be a bunch easier on parts at this power level than a comparable ProCharger engine. The key to the whole deal is converter and gear ratios....everyone wants to put in a mega-tight converter to throw up a big MPH number, but a looser converter is easier to stage and will be more consistent on average tracks. The turbo combination can indeed be consistent; it's all about consistent boost control, as a small change in boost can equate to a big change in power/ET.

The downside to the turbo option is cost and complexity of the system. The Procharger powerplant is much easier to drive and easier to make consistent, without a doubt.

The Procharger system itself is also a little less expensive up front due to the lack of custom exhaust work.

The downside of the Procharger combination is that it takes a lot better engine components to make the power and have any sort of durability. A billet crank is mandatory, as are top of the line cylinder heads. A very good blower bracket system is necessary (5/8 and 3/4 thick brackets with 1" stands and B7 grade 7/16" studs are a must), as is a built-in crank support if a belt driven system is used (this will need to be incorporated into the blower brackets, as systems compatible with Roots/screw blowers won't work with a Procharger). You're also going to spin the engine a touch higher with a blower to make the combination happy, due to the camshaft profiles and converters used in these combinations.All this translates into more money on the engine side and more overall maintenance cost.

So, the question then becomes one of drivability, ease of tuning, overall cost, and maintenance levels.

The turbocharged combination, overall, is less expensive to build and to maintain.

The Procharged system, overall, is less of a hassle to tune and race.

Also, the cost of both total engine/power adder packages is pretty similar. For 2000 hp, you can expect to spend around $40-45K for the engine and its corresponting blower/turbo components. There will undoubtedly be those who will say "so-and-so did it for a lot less", but I can guarantee you that it's not going to be an apples to apples comparison. 2000 reliable, consistent HP out of a Pontiac with a blower or a turbo isn't going to be cheap. Can you make that power for less money? Sure. Is it going to run sixes at 2700 lb on every hit, on every track and be all-season-long reliable? Nope.

I agree with what your saying Travis. Since hes talking about TS racing. Which is still Bracket Racing. I think At this time The blower cars are alittle easier to keep consistant. But either way it takes time and $$$ to get either combo figured out. So its really the persons preferance on which way to go. I like both combinations. WOuld love to be able ot afford 2 cars 1 of each ;-)

Thank you for all the help and insight Travis .

Adam part of the reason turbo's are easier on parts is the drive method... A procharger engine will need 10 hp of drive for every 100 hp added... 2200 hp worth of mass air to net 2000... 200 hp gets eaten up by the drive... a turbo uses no crank power but instead normally wasted exhaust to drive it.

200 hp on the end of the crank and block that wasnt designed for that extra load makes some difference in reliability. That extra 200hp worth of air has to come from somewhere... as mentioned ...higher rpm is where most go to get that extra air... thus adding to the durability equation. The drive itself also needs to be durable.

Turbos using exhuast to drive things also have back pressure which tends to act as a shock absorber for the pistons... at both ends.

Past year or so there seems to be some great improvements in boost control/traction control software that helps from launch to top end. like any good effort it takes data logging to get a good read on whats going on and refine the tune.

Turbo's are load sensitive... more you load them the stronger they tend to come on... they usually dont need or want alot of gear... without good boost/traction control management your car can get slippery at the shift point even though it hooked hard at launch the pull after the shift can get interesting... Sure is interesting to watch a fast turbo car from mid track to finish...

Thank you bruce

Bruce, I'm not sure where your data comes from, but a friend of mine recently ran a 2400 hp capable blower on his blower dyno, and at max impeller rpm, it took nearly 500 hp to turn. That was making around 40 psi on a restriction that simulated a 632 inch engine. Thought you might find that interesting. The blower dyno results are backed up somewhat by the fact that a turbocharged engine of the same displacement at the same boost makes around 500 more hp at the flywheel at the same engine speed. The day we have centrifugal compressors capable of 2500+ hp that only take 200 hp to accelerate is the day that turbo manufacturers start to go broke!

Not true. The combination dictates ratio in a racing application, but the fastest cars are usually running lots more ratio than conventional thinking dictates. Think 5.14 in the rear....

Well Travis, my little excel spreadsheet (compliments of Dave Austin and verified with the math & physics formulas) says that at 40 psi, 85 degree inlet air, 74% compressor efficiency, 12% parasitic losses, and the supercharger actually moving 240 lbs of air per minute (2400 horsepower) would suck up 505 horsepower.

I would say that we are in agreement on your post.

Tom Vaught

Bruce, that Rule of Thumb "10 hp of drive for every 100 hp added" or "One Hp to move One Pound of Air Mass and 1 lb air mass makes 10 hp" " only works for a pressure ratio of about 2 (15 psi boost) At 20 psi of boost you are talking around 120 hp to move 100 lbs of air mass. At 240 lbs/min you would be talking 300 HP. Raise the boost to 25 psi and you are around 150 hp for 100 lbs air mass. 350 hp to move that 240 lbs of air mass. You get the idea.

To add a little more to the discussion:

Something else to consider is that a pump, ANY pump, be it fuel, oil, or air, takes a given amount of horsepower to move a given amount of fluid at a given flow rate.

ACCELERATING this pump from a low flow rate to a higher flow rate takes a great deal more power than operating it at steady state. The faster you wish accelerate this pump, the more power it takes.

This is critically important when speaking about superchargers on race cars, because, unfortunately, they don't operate at steady state for very long. The faster we wish to accelerate the engine, the faster the blower must accelerate as well (it's tied to the crank snout, after all). And, since the power requirement to accelerate the blower increases non-linearly, that blower better be able to keep up when it's called upon.

Nothing on a Boosted Engine is Free.

Belt stuff sucks up Horsepower at an amazing rate when actually raced on the drag strip. Bonneville stuff is a bit easier on things, as Travis mentioned, due to more time to accelerate up to max rpm. But there you have a Density & Temperature change to deal with.

Large PSI style Professional Superchargers consume massive amount of horsepower from the engine going down the track. Marty P's supercharger deal is HP thirsty for sure. Which makes his performance at Tucson Az so impressive.

I still think that we are learning more about boosting every day than any time in history other than pre-during WW-II.

Good Luck with your project Adam.

Tom Vaught

Subscribing :D

Thanks Travis and Tom... I was workin the "rule of thumb" formula.

Turbine drive pressure or more importantly the amount of boost pressure vs exhaust pressure is a very key element to a successful turbo setup... Pressure differential has a big effect on how fast you can build hp and how much you can make. More discussion on that is always welcome.

Agree its amazing what is going on in the turbo world... My old ancient pair of "E" flow Rajay/Rotomasters were "bad boys" on a 350-400 inch engine back in the day(70's)... I think if you really push them maybe 900 max for the pair? If I find a usable turbine shaft for the bad one I may dust them off and find a home for them. Sure are compact and light. (Remind me of my wifes Kirby though :) )

Backpressure has no effect on how much power you can make, within reason. It has absolutely, positively, ZERO influence on the power number. NONE. While it is crucial to know how much backpressure that you're going to have, it is only so that other components, especially the camshaft, can be properly sized.

I have to laugh out loud when someone says to me that backpressure limits horsepower. The backpedals when I tell them that one of the fastest small block cars in history had over a 2 to 1 backpressure ratio are hilarious.

Just to add to Travis' comments, Here's my story...

$34K (includes turbos and fuel system) for the first engine with a home built set of headers, used EFI and the a set of junk e-heads. Rest of the parts are top of the line. Beg for all of the free data I can get, spend lots more money on a dyno, hurt the junk heads and still dont reach 2000hp.

Fast forward to today - Add another 11K for new heads, headers, intake, throttle body and cold side tubing all of which I will build myself.

Add another $2700 for a new EFI system, $4700-$6100 for injectors, and figure $2000 in AN fittings, hoses and various small parts.

Now after thats done add another $7000 for a trans, converter, cooler, and driveshaft.

And I still havent seen it make 2000hp or even know if I can make it reliable..... LOL!! (I'll get there this year...)

If I had any sense 2 years ago or would have listen to people I would have still spend $50K building the engine.

Your car is looking good, good luck with the build.

More on backpressure (its time for a coffee break this morning, I'm dragging).....

To boil it down why backpressure is important in a drag racing application, it all has to do with max engine speed. In nearly any drag racing scenario, engine speed allows for a greater window with converter or clutch tuning, and equates to more power strokes per second. If you have two engines that make the SAME peak/average power, but one does so at 1000 higher rpm, and the race car is geared to take advantage of that additional rpm, that will be the faster car, even though the power number is the SAME.

A turbocharged engine with a high backpressure number can make the exact same power number that one with very low backpressure can. It can make the same average power over its operating range that a low backpressure engine can over its operating range. The difference is what that operating range is! High backpressure forces you to run a camshaft with very little overlap. Small overlap numbers means that the engine isn't going to rev. Also, high backpressure applications (like street cars) are not overly sensitive to valve timing events, since the cams are already so small. You can put nearly anything in it, and so long as the overlap isn't too crazy, it will run just fine.

Low overlap engines act a lot more like a NA engine, because there starts to be a small amount of scavenging on the overlap cycle. So these engines can sometimes be a lot more picky about camshafts.

The bottom line is that for the typical drag race engine, it's not worth losing sleep over backpressure, because most guys don't really want to spin their engines over 8000 rpm anyway, or don't have the components to take advantage of it if they did. The gains from reducing backpressure aren't going to come from a huge gain in horsepower; they are going to come from the additional engine speed afforded by a low backpressure combination. And for a typical T/S application, a high backpressure combination may not be all bad....a high backpressure combination is usually one that has a very responsive turbo combination, which means that it will be really easy to get the turbos to follow the boost controller.

I will post a couple of comments from the Garrett People and the Borg Warner people about pressure across the inlet and outlet of the Turbine.

Garrett:

"http://www.turbobygarrett.com/turbobygarrett/turbine_housing_AR_and_housing_sizing
Turbine A/R - Turbine performance is greatly affected by changing the A/R of the housing, as it is used to adjust the flow capacity of the turbine. Using a smaller A/R will increase the exhaust gas velocity into the turbine wheel. This provides increased turbine power at lower engine speeds, resulting in a quicker boost rise. However, a small A/R also causes the flow to enter the wheel more tangentially, which reduces the ultimate flow capacity of the turbine wheel. This will tend to increase exhaust backpressure and hence reduce the engine's ability to breathe"" effectively at high RPM, adversely affecting peak engine power."
Conversely, using a larger A/R will lower exhaust gas velocity, and delay boost rise. The flow in a larger A/R housing enters the wheel in a more radial fashion, increasing the wheel's effective flow capacity, resulting in lower backpressure and better power at higher engine speeds.
When deciding between A/R options, be realistic with the intended vehicle use and use the A/R to bias the performance toward the desired powerband characteristic.
Here's a simplistic look at comparing turbine housing geometry with different applications. By comparing different turbine housing A/R, it is often possible to determine the intended use of the system.
Imagine two 3.5L engines both using GT30R turbochargers. The only difference between the two engines is a different turbine housing A/R; otherwise the two engines are identical:
1. Engine #1 has turbine housing with an A/R of 0.63
2. Engine #2 has a turbine housing with an A/R of 1.06.
What can we infer about the intended use and the turbocharger matching for each engine?
Engine#1: This engine is using a smaller A/R turbine housing (0.63) thus biased more towards low-end torque and optimal boost response. Many would describe this as being more "fun" to drive on the street, as normal daily driving habits tend to favor transient response. However, at higher engine speeds, this smaller A/R housing will result in high back pressure, which can result in a loss of top end power. This type of engine performance is desirable for street applications where the low speed boost response and transient conditions are more important than top end power.
Engine #2: This engine is using a larger A/R turbine housing (1.06) and is biased towards peak horsepower, while sacrificing transient response and torque at very low engine speeds. The larger A/R turbine housing will continue to minimize backpressure at high rpm, to the benefit of engine peak power. On the other hand, this will also raise the engine speed at which the turbo can provide boost, increasing time to boost. The performance of Engine #2 is more desirable for racing applications than Engine #1 since Engine #2 will be operating at high engine speeds most of the time."

So basically Garrett is singing the same old song: "higher engine speeds, smaller A/R housing will result in high back pressure, which can result in a loss of top end power"


Borg Warner:

http://www.turbodriven.com/en/turbof...gnTurbine.aspx

Borg Warner says that Higher Pressure across the Turbine is not necessarily a bad thing:

The turbocharger turbine, which consists of a turbine wheel and a turbine housing, converts the engine exhaust gas into mechanical energy to drive the compressor. The gas, which is restricted by the turbine's flow cross-sectional area, results in a pressure and temperature drop between the inlet and outlet. This pressure drop is converted by the turbine into kinetic energy to drive the turbine wheel. Energy transfer then happens (from kinetic energy into shaft power in the turbine wheel, which is designed so that nearly all the kinetic energy is converted by the time the gas reaches the wheel outlet.

The turbine performance increases as the pressure drop between the inlet and outlet increases, i.e. when more exhaust gas is dammed upstream of the turbine as a result of a higher engine speed, or in the case of an exhaust gas temperature rise due to higher exhaust gas energy. The turbine's characteristic behaviour is determined by the specific flow cross-section, the throat cross-section, in the transition area of the inlet channel to the volute. By reducing this throat cross-section, more exhaust gas is dammed upstream of the turbine and the turbine performance increases as a result of the higher pressure ratio.

A smaller flow cross-section therefore results in higher boost pressures.

The turbine's flow cross-sectional area can be easily varied by changing the turbine housing. Besides the turbine housing flow cross-sectional area, the exit area at the wheel inlet also influences the turbine's mass flow capacity. The machining of a turbine wheel cast contour allows the cross-sectional area and, therefore, the boost pressure, to be adjusted. A contour enlargement results in a larger flow cross-sectional area of the turbine.

For a high overall turbocharger efficiency, the co-ordination of compressor and turbine wheel diameters is of vital importance. The position of the operating point on the compressor map determines the turbocharger speed. The turbine wheel diameter has to be such that the turbine efficiency is maximised in this operating range.

The turbine is rarely subjected to constant exhaust pressure. In pulse turbocharged commercial diesel engines, twin-entry turbines allow exhaust gas pulsations to be optimised, because a higher turbine pressure ratio is reached in a shorter time. Thus, through the increasing pressure ratio, the efficiency rises, improving the all-important time interval when a high, more efficient mass flow is passing through the turbine. As a result of this improved exhaust gas energy utilisation, the engine's boost pressure characteristics and, hence, torque behaviour is improved, particularly at low engine speeds.

I personally tend to agree with Travis Q and the Borg Warner people in that High Turbine Pressure Numbers do not necessarily always result in Top End HP losses. Basically you have to look at what you are trying to do in each application and then go from there. "Rules of Thumb" are ok but actual data that says "if i do this then I actually got this" is always better. "One piece of data is worth 1000 Opinions" (James Clarke)


Tom Vaught

If superchargers need so much HP to produce then why are they a viable option vs. turbos?

Relative simplicity?

Sort of. They are considered "easier to race" like a nitrous car vs a turbo car. It is an easier transition from nitrous to boost with a procharger than to turbo due to the methods of power management used.

Over-simply put, you slow the crank down, you control the power, you can do that with a graphs in a digital 7 just like you can with a nitrous car. With turbos you have boost controllers to deal with to program the ramps. Basically, pro-chargers have been viewed as less of a learning curve and something you could eventually do on your own, while turbos have had a stigma of always needing to have a "tuner" on hand helping with your program to go fast and win races.

Then when it comes to driving the car you stage a procharger car just like a nitrous/NA car, while a turbo car you had use to have to learn how to build boost, ride the breaks, bump in etc. Of course now, you put the right converter in the car and it comes up on boost quicker, stages easier, etc. Or you can use a "bump box" like a friend of mine makes where you bump the trans break button:

http://www.leashelectronics.com/Puls...tem-PL2000.htm

If you already had a nitrous car, it was easier to convert to pro charger as you could often re-use many components that were on the car vs "having to start fresh" with a turbo swap.

Obviously things have been changing at a rapid rate for turbo cars in the past couple of years, the stigma about the tuners is going away as more guys are "doing it on their own", procharger can not keep up with the technology advances in turbos in class racing leading more and more guys going to turbos which probably has something to do with that, I know of one car and another in progress that can be swapped from turbo to procharger in a few hours (power adder, converter, cam, gear, EFI program) in anticipation of class rule changes if one power adder has the advantage over the other in the class, the turbo and procharger uses the same ramair inlet in the lower front fascia, if you have the extra 10-15K to spend for the parts to sit in the trailer, it is what you can do when you want to win a championship...

Interesting for sure.