Tim Murphy

The guys name is John Scott and I think he lives (his parents house) in North Lake Wisconsin. When I looked at the car he said it was still titled in Florida, where he bought it. The car was originally red and he painted it black, with a lot of red to still be found. Be prepared if you do get ahold of him, he is a complete moron.

John..

I stumbled across some literature on Callaway's 944 turbos. These cars made 280 HP on 2.5 liters, 10 psig of manifold pressure and 8:1 compression.

<a href="http://members.rennlist.com/tholyoak/callaway.html" target="_blank">http://members.rennlist.com/tholyoak/callaway.html</a>

This is good, because not only do the early 944 and 928 share block head and piston technology, the Callaway 944 turbos had thier pistons machined to drop compression down to 8:1.

Now I feel more than safe holding my gates closed until I get to around 10 or 11 psig. I just am not sure how to do the additional fuel just yet. I can increse the pressure or drop in larger injectors. I have to run some numbers to see.

Looks like the Callaway 944 made 112 HP per liter. I have 4.5 liters, so perhaps I can make 500 HP? Probably not, but 425 -475 HP should be reasonable on 11 psig at the manifold. The 944 used one RHB6 turbocharger and fed 2.5 liters at 10 psig. My RHB6 should be able to feed 2.25 liters at 11 psig no problem.

I have lots of figuring and the like to do before I get to work. It has been colder than a witch's you know what here, so my garage time is minimal right now.

Drewster67

John, thank you for your input and time spent. Please don't detour as a few of us are anxiously awaiting your final synopsis.

BTW - I have all the windows down in the house, Sunny as all can be and it's 75 degress outside. I'm sorry I couldn't resist. :-)

Jim Nowak

John,

I'd have to agree with Car and Drivers summation of the Calloway 944 turbo. I do not believe it had 280 hp either. Let's do the math. You reduce the compression in the 944 motor and your RWHP will go to around 115. Add 11 psi of boost to that with no intercooler and you get around 170 RWHP or around 213 crank hp. The 86 944 turbo had 215 horsepower and could do 60 in 5.5 seconds and the quarter mile in the mid 13 second range. The Calloway is slower than a bone stock 86 944 turbo so I don't think it really had as much power as they advertised.

Let's look at your 928. A healthy stock US '82 or '83 928 will dyno around 180 to 190 rwhp. Pump 11 psi into that motor with a 3 core intercooler and you will get around 332 RWHP or around 415 crank hp.

This calculator works: <a href="http://www.superchargersonline.com/hp_calculator.asp?submit=1" target="_blank">http://www.superchargersonline.com/hp_calculator.asp?submit=1</a>

Mongo

This hype for turbochargers has reminded me of an idea i had a while ago. I made some drawings of what a turbocharger converted 928 S4 motor would look like...I think I'll start beginning some more R&D about that and see if a tuner would like to join me in this pursuit to a hybrid prototype <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" />

<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

Fastest928

I started a twin turbo project and then realized...what do you do with a 800+ hp/tq twin turbo engine except break things?

So, I have for sale: two new T40E non water cooled turbos...big...sized for 6.0 l, each capable of supporting 400+hp. $1500 for the pair

1 set of new, machined only low compression GTS spec forged mahles 100.5mm pistons. $3000 per set

stroker crank and rods are already taken....

High flow low comp heads will be usedona suprcharged project coming up.

email me privately.

Marc

Old & New

Marc,

Is it official, then?

Devek's out of the TT business.

Or just not in yet?

<img border="0" title="" alt="[Wink]" src="wink.gif" />

Looking forward to your SC project, though.

John.

Jim,

Those numbers for the 944 were verified on an engine dyno at Callaway's shop. Personally, I think that Car and Driver article is a bad representation of the potential of the cars. I know for a fact that my car makes over 300 HP now, because it is a good bit faster than a stock 928 S4 and those made over 300 HP. The article has a lot of errors, like stating the 928 had two microfuelers. That just ins't true and whoever wrote it (Csere?) wasn't paying attention when he looked the cars over. Five bucks says some non-technical author estimated those HP numbers.

The Callaway turbo 944 was equipped with an intercooler. As for a stock factory 86 944 turbo. Well, I have never seen one run the kind of numbers you claim, even in all of the road tests done on them. Maybe for the Turbo S with the 247 HP motor, but certainly not the 86 turbo. More like 6.2 seconds and 14.5 seconds. Also, those topped out at around 152 MPH. The Callaway 944 was top end clocked at 161 MPH...probably right at the top of 5th gear, because my stock 83 runs 3050 RPM at 80 MPH. I don't think they ever made any gearing changes in the cars.

The surpercharger calculator is cool, but turbos are somewhat different. It takes a lot of HP to run a supercharger feeding a V8... power right off the crank. I assume the calculator takes this into consideration. So with a turbo setup you have more efficiency but you also have lag. Drive it mechanically and you get rid of the lag, but you also consume more power.

The 928 motors were never dyno tested by Callaway, but the 944 motors were. Based on the performance numbers of the 944, I believe the HP specified is close to being spot on accurate. They may have dialed in a bit more on the dyno with some 100 octane fuel, but 270-280 is reasonable (perhaps a tad high...maybe 10 to 20 HP) with the performance numbers posted.

Talking with Reeves directly, he had estimated the 928 was right around 400 on the crank when it left the factory. The only issue with the work they did was the fuel enrichment methods. Not the best, but it was all that was available at the time they put these cars together. My solution is to run it a little fat and hope for the best.

The dyno will tell the real truth. I'll know in a few month's time what the real number is....just as soon as this deep freeze let's go and I get off some cash to buy the parts I need.

Jim Nowak

John,

Your right, I forgot to include the saprophytic loss of the supercharger. You can add another 25 hp to that and bring it up to around 237 hp. You can also back into the proper horsepower by this formula. hp = weight / (ET / 5.825)3 An '83 944 weighed around 2800 lbs. The power gain Calloway quotes just seems to be a little too high for that boost level.

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva"> I know for a fact that my car makes over 300 HP now, because it is a good bit faster than a stock 928 S4 and those made over 300 HP. </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">The difference would be the weight of the S4 vs the 944. There is a big difference, given equal power, in performance with a car that weighs 2800 lbs vs one that weighs 3500 lbs.

Mongo

T40E? no wonder why there's 800 HP! <img border="0" title="" alt="[Eek!]" src="eek.gif" /> What if the use of a small turbo like the K24 off the 993 and 996 turbos was installed on a 928? it would yield a reasonable power gain with plenty of torque and HP to keep ya the quickest car in town

<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

John..

I just purchased another reference on turbocharging engines. It is called Maximum Boost by Corky Bell. This is a great book for anyone considering converting a car to turbocharged status (Drew). Not an engineering text, but a very down to earth reference book on the subject.

There are some crude formulas in there for determing the HP of a turbocharged engine based on displacement and manifold pressure. These are:

Lower Value=0.052*cubic inch displacemnt* (boost level +14.7)

Upper Value....same equation, substitute 0.077 for the constant.

Plug in the numbers for the Callaway 944 and you get 192 HP up to 285 HP. (10 psig boost level, 150 cubic inches)

These are figures derived from dyno experience with a vast number of engines. Basically it gives a range of expected HP. Crude but basically effective.

Personally, I don't think 1/4 mile times are all that effective at estimating HP of a turbocharged car. Typically you don't get full boost until 2nd and 3rd gear, so the results may be somewhat skewed. It may give you an average HP through the 1/4 mile, but that is about it.

The 300 HP I was referring to was for my Callaway 928 as printed in the C&D article.

Anyone considering turbocharging anything should take the time to read this book. It is excellent, probably the best $38.00 I have ever spent on a book.

Drewster67

I'm on it - Thanks John.

Jim bailey - 928 International

One of our customers had a Callaway blew the engine and replaced it with an S-4 engine with cams , he said it was much faster after the swap . It now has a GTS engine with GT cams and is faster yet . Point being , it was not making big power just big reliability problems with the turbo . Can it be done ? certainly . Is it simple and inexpensive ? not if done correctly . Marc Thomas ( who truely does recognize what the project requires ) lists $4,500 for just some of the parts and it is a complete engine rebuild as well before addressing the fueling requirements ! Anything less is going to require limited boost and major compromises . Turbo engines with the increased exhaust restrictions often have the headers/manifold so hot it is glowing cherry redhot . Which is a big issue under the hood of a 928 deciding which items you wish to barbeque . Will it be the motor mounts , undercoating , plastic radiator tanks , clutch fluid hose A/c compressor ......or all the above .

John..

Jim,

My car has been making a very reliable 350+ HP for over 20 years with no driveability problems whatsoever. I don't know of anything offered by the factory, including the Euro spec cars which made that much power back in the 1982-1983 time frame. Is it a perfect kit? Of course not, but it has proven very reliable over the years. All of the items you list cooking are still in tact and work as new. Callaway's work wasn't perfect, but it was a very good attempt at squeezing a lot more power out of the 928's engine. Remember, the S4 and GTS engine didn't even exist way back in 1983. So for 1983, it was probably one of the most powerful (if not the most powerful) 928s in the country.

As I stated in earlier posts, the only real lacking stuff with the kits was bullet-proof fuel system enhancements. They were crude, but did work, and again that was all that was available 20 years ago. The rest of the work is really very beautiful and works well on my car. Whoever made the headers and exhaust system really knew how to work a tig...

If this was a twin version, I would be interested to know if there are any spare parts left over..., or if the owner is interested in parting out the kit, or selling the entire kit.

Steve Cattaneo

Jim B,

Turbo engines with the increased exhaust restrictions often have the headers/manifold so hot it is glowing cherry redhot .

It this what you mean? <img src="http://www.mastertechtrans.com/post/enigne.jpg" alt=" - " /> <img border="0" title="" alt="[Eek!]" src="eek.gif" />