RCR 917 drivetrain possibilities

[John]

Hi all,

New to the forum since I just put the deposit down for a RCR 917. Plan is for me to supply Fran with drivetrain and he will put it in for me to make it a turn key. The question now is what are the drivetrain that would fit in a 917.
Been talking to Fran and he suggests using either 3.2 Carrera engine with G50 or 915 gearbox, or LS3 with G96 gearbox. While I'm totally fine with these choices I've been thinking if there are other more "spicy" options that will fit (ie high revving v8's like Audi 4.2, Ferrari V8's; 996/997 GT3 motors, or even other v10 and v12's).

I understand that cost of choices other than LS and 3.2 engines can go up exponentially after all the engine electronics are sourced, but I'd love to have more options.

Thanks in advance for any advice! -John

 

[Neil]

Hi all,

New to the forum since I just put the deposit down for a RCR 917. Plan is for me to supply Fran with drivetrain and he will put it in for me to make it a turn key. The question now is what are the drivetrain that would fit in a 917.
Been talking to Fran and he suggests using either 3.2 Carrera engine with G50 or 915 gearbox, or LS3 with G96 gearbox. While I'm totally fine with these choices I've been thinking if there are other more "spicy" options that will fit (ie high revving v8's like Audi 4.2, Ferrari V8's; 996/997 GT3 motors, or even other v10 and v12's).

I understand that cost of choices other than LS and 3.2 engines can go up exponentially after all the engine electronics are sourced, but I'd love to have more options.

Thanks in advance for any advice! -John

I would not consider using a Porsche 915 transaxle these days. A G50 is stronger and smoother shifting. A V10 offers no advantage over a V8 but the V12 is an inherently balanced design. $$$, though.

 

[John]

I've heard about @V12Esprit and his R8 powered SLC, would you chime in on this?

 

[Howard Jones]

So I think the EASIEST power train would be a flipped G50 Porsche and a normally aspirated flat 6 Porsche motor using carbs. This way you maintain the Porsche lineage and IMHO greatly enhance the value of the completed car. Little to no electronics except the ignition box. I believe that about 300-350 hp would not only be doable but not completely bust the budget. You would also save some money on Fran's labor by keeping it simple.

A second way to go would be to buy a doner Cayman S (345hp). The whole car with the powertrain in it where the engine runs and the GRBX works. Now you can pull out the electronics, harnesses, sensors, etc. as a working complete package and install it with the engine/GRBX into the 917. This will cost more labor building the car but hopefully save some after-the-fact troubleshooting/development costs. Maybe look for a head-in crash damage totaled car. When you are done you can sell the rest of the cars parts. Interior, doors, surviving glass, chassis parts, wheels, etc. You will want one that has the front of the car crushed and both front fenders ruined BUT little damage behind the A-pillars. 2014 or later to avoid the engine bearing problems of the earlier cars.

The last idea was a SBC Chevy with a carb and flipped G50. Very little electronics and simple installation with lower labor expenses. You can still buy a low $6000 350 @ 350-375HP.

These were the three options I came up with where I was looking at a 917 instead of the SLC I did in the end.

One thing to really look at is that flat Porsche engines are EXTREMELY expensive to build above about 400HP. A 500HP flat 6 Porsche would cost 3 to 4 times more than a 535 HP LS crate motor.

The bottom line is this IMHO, the development cost of tuning the electronics can be huge if it is a custom system. IMHO try to stick with a factory system and components from a doner even if you use a FI Porsche motor.

I think Fran is on the right track. I would be interested in what motor he is thinking of.

Note: Neil is right. G50s are a much better choice than a 915.

 

[Kev Farrington]

There are a couple of things that drive my enthusiasm for replicas. One is original manufacturer for components etc so Porsche engine and gearbox is important The other is the sound they make. A Porsche flat 12 would be great but there isn`t much living space inside a 917. Even if I sold the house to buy an engine it wouldn`t be enough. If it would fit I might try a BMW V12 or Mercedes V12. That way it would be German at least. Sticking a couple of flat 6`s together might be too long but is an idea I had year`s ago and I might still try. The BMW V12 idea might be the easiest but go with what suits you. It`s your dream?

 

[Mark B.]

A compromise option could be to do 180-degree headers on an LS. Basically makes it sound like a flat-plane. Example: DES 180 Degree Headers in LS7 swapped Porsche 997 - Duke Engineering Solutions - YouTube

 

[Howard Jones]

Go out to a track day or better yet a real race that features Porsche Cup race cars. I think they sound great at fullsong. And a 917 so we have a comparison.