901 or 915

KID914 · KID914's Garage

I have a 73 2.0 914 . I'm looking to convert it to a 3.6, with possibly a turbo or twin turbo set up...the goal is to get around 2000 lbs-400 hp and 200 mph can i keep my 901 tranny and rebuild it, or am i better with a 915 like most race cars?
please help!

Cairo94507 · Cairo94507's Garage

I have to say go 915. I am putting a stock 3.2 in my six and I am going with the 915. I know it costs more but I do not want to have to worry about being gentle in 1st gear, not that I am going to race the car, but I would rather build it right to begin with. Good luck.

Matt Monson · 01-13-2011, 02:48 PM

3.6 with a turbo and 200mph? Neither 901 nor 915. You're into 930 or G50 territory...

KID914 · KID914's Garage

I figured a g50 would be my best bet. I have no intentions of racing it (at least not professionally) LOL. I 'm trying to keep my budget inline, but i want to know if i need the power and speed to kick domestic (butt) i have it.

SirAndy · 01-13-2011, 04:05 PM

Quote:

Originally Posted by KID914

I figured a g50 would be my best bet. I have no intentions of racing it (at least not professionally) LOL. I 'm trying to keep my budget inline, but i want to know if i need the power and speed to kick domestic (butt) i have it.

I run a 3.6L with a stock 901 and it works just fine.

However, judging from your posts, you are in the younger than 30 bracket.

I lost the need for burnouts a long time ago. I don't use 1st gear anymore and simply take off in 2nd. Still plenty of go ...

If you like to beat on 1st gear and tire smoke gives you thrills, the 901 will not work for you (not for long anyways).

As said above, if i was going to add a turbo or two, i would most certainly go with a G50 or similar. You'll need a limited slip as well ...

KID914 · KID914's Garage

LMAO. Thanks for the compliment SirAndy, but i'm a 40 years young. I promised myself i'd own a porsche by the time i turned 40,surprised i stayed true to my word.It's a fixer for sure,but worth saving.
Thanks for the info...i though my best bet would be a G50.

KID914 · KID914's Garage

SirAndy what are your running numbers for your 3.6.
I saw another thread ,where you said a 901 with a ZD fift gear, one could reach 190 mph with good torque. How would that work for longevity.
INTERESTING!

John Rogers · 01-15-2011, 12:10 PM

If you are looking far enough ahead for the 3.6L engine and then some time putting a turbo on it then you'll need the G50 with limited slip. You could use a flipped Turbo transmission as that is what the 914 Bonneville car had and some seriously tall gears such as 95 in 1st, 145 in 2nd, 185 in 3rd and it was calculated to go 205 on 4th but always spun out since they were not allowed a wing. If you are going to go much over 120 then you'll need some downforce and larger wheels/tires and much better than stock suspension AND brakes! A seemingly small item that can pose a headache is the stronger axles and CV joints you'll need since the stock ones will never handle the power. Andy has his pretty much setup for a hot street car with some auto-x use so that would be the way to go with his parts list.

trekkor · 01-15-2011, 07:36 PM

ZD 5th @ 8000 rpms is 170 mph...

Where are you planning to hit 200mph, anyway?

KT

KID914 · KID914's Garage

thanks John for the advise.

Matt Monson · 01-18-2011, 08:24 AM

Something to keep in mind is that the only place a 914, even a 914 with that sort of power, is going to be able to go 170mph is a roval like Daytona or Fontana where you've got a NASCAR bank and some room to stretch your legs. I doubt with the drag on a 914 you could even hit 170mph at Sebring. Gearing the car for 200mph is a waste of time, IMO.

John Rogers · 01-18-2011, 07:07 PM

Having raced with some newer Porsche race cars when we were having our vintage races at Fontana I noticed that they all had wings (raised), splitters and big assed tires to be able to go 170 or so on the banking of NASCAR turns 1 and 2. The stock bodied cars, I.E. early 911s and 914s could do 135 or so and many would drift in the turns due to lack of downforce. The guys running the vintage NASCAR race cars as the old IMSA cars could actually get to close to 200 MPH as one of the Mclarrens and Ferrari F1 cars did.

P9elfer · P9elfer's Garage

I once installed a 350HP Chevy V8 in a 914 with the stock transmission. The instruction to the customer was to not use first gear. The transmission held up well even though the fellow would always light up the rear tires.

Matt Monson · 01-20-2011, 07:28 AM

Quote:

Originally Posted by john rogers

Having raced with some newer Porsche race cars when we were having our vintage races at Fontana I noticed that they all had wings (raised), splitters and big assed tires to be able to go 170 or so on the banking of NASCAR turns 1 and 2. The stock bodied cars, I.E. early 911s and 914s could do 135 or so and many would drift in the turns due to lack of downforce. The guys running the vintage NASCAR race cars as the old IMSA cars could actually get to close to 200 MPH as one of the Mclarrens and Ferrari F1 cars did.

Yeah, I wasn't even addressing the tendency of the 914 to get light and turn into a wing at high speeds. I was just looking at the coefficient of drag and what kind of speeds it can reasonably hit in a closed course environment. Being able to actually hit those speeds safely is a whole nother thing all together beyond having the power and gearing to get up there in the first place.

SirAndy · 01-20-2011, 10:05 AM

Quote:

Originally Posted by Matt Monson

Yeah, I wasn't even addressing the tendency of the 914 to get light and turn into a wing at high speeds. I was just looking at the coefficient of drag and what kind of speeds it can reasonably hit in a closed course environment. Being able to actually hit those speeds safely is a whole nother thing all together beyond having the power and gearing to get up there in the first place.

The coefficient of drag for a stock 914 is actually pretty good, in fact, it's better than a early 911 turbo ...

Matt Monson · 01-20-2011, 01:53 PM

I didn't say it was bad.

But when we're talking about 170mph+ aero matters. An off the shelf 3.6l turbo swap is not going to be getting a 914 chassis up to those speeds to my way of looking at it.

BTW, just by way of gratuitous self promotion here, one of our gearboxes recently set a record on the Fontana Roval. 175mph and they hit the rev limiter because we geared it just a touch too short.
http://www.youtube.com/watch?v=bw6rYNPxrIk

SirAndy · 01-20-2011, 06:06 PM

Quote:

Originally Posted by Matt Monson

But when we're talking about 170mph+ aero matters

I agree

With my stock 901, i top out around 135mph and the car does not feel safe at that speed.

One would need some serious help in the downforce department to go beyond that.

larrym · larrym's Garage

talk to Patrick motorsports - they told me they gave up on G50 installs - too much trouble & mods - so i sold my G50 & am looking for a 915

Cairo94507 · Cairo94507's Garage

Sounds like a reasonable solution. If PMS says it was to much work, I would believe them. I am at this point not going to worry about a transaxle until it is time for engine and transaxle. First I have to get the whole car ready for the drive-train. Hopefully by the time I am ready I will know which direction to go. Best wishes on your build.

mcfoo · 06-27-2011, 11:11 AM

If you go with 915 you'll need to go with a WEVO or other shifting device.

What ever you do ,don't use the Patrick Motorsports cable shifting system.I bought a car with that in it. IMHO a "fnnnnn' disaster. But if you would like to try it, I'll sell it to you real cheap.

Your other choice are some replica 916 tranny parts being produced by some folks in Germany. Not cheap.