What all is need to tt a 993 VRAM motor?

[tradin1]

Decided I want more pwr for a 72 rsr project. I already bought a VRAM motor.

I've been told shaving the pistons, rods, and head studs was all that was needed for the motor internals...is that true?

[911st]

Yes, you should lower the compression ratio. You can do this by having the piston domes machined or buying a set of custom J&E pistons..

If you stay under about 11/1 effective compression ratio under boost (somthing like .8 bar with 8/1 compression), your ignition side should be ok with knock sensing.

The challenge is the fuel side. You will need to relocate the hot wire air flow sensor to before the turbos as any oil from them might kill it. You will probably need larger injectors or a Raising Rate Fuel Pressure Regulator. Then you will need a custom chip to support your build. Try 911CHIPS.com or Protomotive. Otherwise you will need a custom aftermarket programmable EFI system. Another possibility is to use a UniChip piggy back system to fine tune things.

You might want a larger MAF sensor than stock.

That on top of your typical turbo, exhaust, and inter cooling plumbing.

Never done it so this is mostly an educated guess.

[tradin1]

so the 993 NA case, crank, heads, and pistons can handle the stress of turbo charging stress?

was going to go ITB and MoTec.

[WERK I]

Rod bolts - No. Use ARP rod bolts/nuts
Pistons - No. Shaving pistons weaken crown.
Head Studs - suspect. NA 993's did not use the 993 Twin Turbo head studs. Go with ARP or Raceware, Supertec head studs. 993TT head studs are now nearing $40 a piece! Yikes!

'72 RSR hot rod sounds like a cool project.

[911st]

Sounds like you are talking a higher level of tune. I was thinking about 450hp, you sound like you are thinking in the 600hp range.

ITB's I suspect is more about throttle response as they eliminate the volume between the throttle body and intake valves. The may add some power in an extreme build targeted at a very competitive race class. The not necessary for a big HP motor that can overwhelm a long hod chassis if not built right.

Motec is excellent if you have a good tuner that knows it.

I guess I would say, start with a lot of money and find an experienced builder to protect your investment if big, big HP is your goal as there are a lot of other little detains like if you should go to mechanical valve train or such.

[RarlyL8]

Marty (Copbait73) has done this and should have some insight.

[tradin1]

Yes the itb's are instant throttle response. This is going to be a street car. Thx for all the advice, sounds like the case is up to the task.

What crank does everyone recomend? I'm beingtold an offset 3L crank with some long rods with je 3.6 pistons.

[911st]

There are ITB's that will fit under your 993 manifold from a 993RSR I believe. The non VR manifold would be better with less volume. Such an approach would reduce fab work and has been used up to 1000hp.

Do not know about your crank ideas.

Upgrade rods if you are going over 6700rpm are a must. You can get J&E pistons with higher or offset wrist pins I believe. A GT3 crank and oil pump would be an upgrade. GT3 rods seem to be good to 8000rpm.

What is your goal. An 8000rpm 700+hp GT2 motor or a solid 7000rpm 550hp street / DE motor.

[9dreizig]

Talk to Gabe (reaper930), he did the ITB on the blackbird
Welcome to the darkside!

[WERK I]

Originally Posted by 9dreizig

Talk to Gabe (reaper930), he did the ITB on the blackbird
Welcome to the darkside!

Darkside, indeed. Other's that may be able to provide advice; Richard Clewett of Clewett Engineering, Steve Weiner of Rennsport, Bob Holcombe of Mode, Inc., Jerry Woods of Woods Enterprises. These guys have done the exotic 993 builds numerous times.

But.....be sure and keep us posted on what you find. We're all members of the "darkside".

[tradin1]

I would like as linear power deliver as possible. 700 sounds great but not necsarry. I am deff going to put a race logic traction control in the car.

Deff going to upgrade the rods and use arp studs everywhere I can.

I was going to have a plenum fabed out of al.

I will pm the above members mentioned and keep the thread updated.

[K24madness]

There have been many stock 993 vram conversions using stock internals. If you limit boost to 6psi you will be safe on 93-94 oct fuel. If you only have access to 91 I would not do it.

Here is a dyno from mine at 6psi. I run 100 oct just to be safe.

[TurboKraft]

If you're not looking to make 600+hp, the stock rods will work with ARP rod bolts.
Replace the pistons, or pistons & cylinders (there are very safe slip-fit 3.8L P&C sets, like we offer and use).
Replace the head studs (we use and sell ARP).
Add boost.

ITBs -- I can help you with that, have a set available complete with plenums, or can make a new system for you. And yes, it'll rev like a motorcycle and let you run some huge cams for big, broad power that otherwise would not work on a single throttle intake manifold.
The 993 3.8RSR throttles don't bolt up, different 3-bolt pattern on the RSR heads and wider port spacing than street heads.
If cost becomes an issue, though, the single throttle body 1995 intake will easily support 700hp and leave plenty of room for a big air:air intercooler (unlike the VR manifold which leaves very little room).

EFI -- Motec, AEM, Autronic... as mentioned above, think a lot about the support you'll need and can get, especially if you plan on doing all the installation & tuning yourself. We use AEM and Motec.

Also have an almost complete twin turbo system available. Give me a call if you are interested.

A properly designed single turbo system will save a lot of money and fabrication and can get you nearly the same low rpm torque.

Cheers,