993 VRAM head on my 911SC???

[storegnu]

Hi, all!

I have a somewhat modified 911SC Targa. The engine is originally a -82 180hp US unit, but has been rebuilt and has basically this configuration now:

- 911SC intake, small port, opened to 39mm.
- Heads ported to same size.
- 964 cams.
- Euro cylinder set (3.0l)
- Maxxecu EFI, DBW throttle.
- 964 oil pump.
- Stock rods, but with ARP fasteners.
- Stock crank.

It makes 218 WHP on the dyno and runs really great, but power is dropping like a rock from 6500 rpm. Torque peaks at 5500. I guess that the stock intake is really showing its limitations.

A friend of mine has a complete 993 VRAM intake I can have at a very reasonable price. I am thinking of swapping my stock intake for this and control all the flap features through Maxxecu. I am then also contemplating a new cam, maybe going wild with something like a DC80 cam, combined with raising the rpm limiter to 7300rpm (7200 today).

What do you guys think about this? How much power could I gain? In my head it should gain torque all the way and quite a bit of power as well after 6500 rpm. In theory it is quite easy for me to change out “just” the intake and the cam, so I am really tempted. Unfortunately I can find very little info about using 993 VRAM intake on my engine, so I am a bit unsure of what to expect.

[stownsen914]

No experience with the VRAM, but that's an interesting idea and probably would breathe better than the SC intake. On the cams, the grind will be an important choice. High overlap cams don't tend to like common plenum arrangements with a single throttle body. The inconsistent pulsations from lumpy cams reportedly make for poor low RPM performance.

[PeteKz]

What do you plan to use the car for? Street, track, etc.? That will determine your cam choice and intake choice. For a primarily street car, you don't want to give up low RPM torque and drivability for high RPM power. On a race car, you do.

[phunt]

Isn’t a v-ram a 3 bolt intake?

[storegnu]

Originally Posted by PeteKz

What do you plan to use the car for? Street, track, etc.? That will determine your cam choice and intake choice. For a primarily street car, you don't want to give up low RPM torque and drivability for high RPM power. On a race car, you do.

Hi, Pete! This will be a fun car for canyon carving, but also for road trips. Agree that I will not give low RPM, but was hoping that the VRAM intake would help me down low, even with an aggressive cam.

[storegnu]

Originally Posted by phunt

Isn’t a v-ram a 3 bolt intake?

Correct, but there are adapters.

[silverlock]

There’s a thread on the 964 (alu or plastic) intake manifold -> 3.0/3.2 here: https://forums.pelicanparts.com/911-engine-rebuilding-forum/926823-964-intake-manifold-3-0-3-2-port-adapters-2.html with the Adapt Motorsports adapters to fit the bolt pattern.

That and a 964 or 994 throttle body to open it up, since you have a standalone setup.

[JoeMag]

How about asking your friend to let you 'borrow' it to try? I am not operationally familiar with the SC intake so not sure if that's what's limiting you. Maybe others can weight in.

Do you have an atm pressure sensor on your ECU? If so, plumb it to your intake and see if you're starting to draw vacuum on it.

As a data point, I ran a 964 plastic intake and it supported 100+ more wheel Hp than what you have.

[storegnu]

Originally Posted by silverlock

There’s a thread on the 964 (alu or plastic) intake manifold -> 3.0/3.2 here: https://forums.pelicanparts.com/911-engine-rebuilding-forum/926823-964-intake-manifold-3-0-3-2-port-adapters-2.html with the Adapt Motorsports adapters to fit the bolt pattern.

That and a 964 or 994 throttle body to open it up, since you have a standalone setup.

Thanks, I have found a Swedish company that also sells adapters, they look really nice: https://islandworks.se/products/billet-intake-runners-for-porsche-g-model-to-964-993

[storegnu]

Originally Posted by JoeMag

How about asking your friend to let you 'borrow' it to try? I am not operationally familiar with the SC intake so not sure if that's what's limiting you. Maybe others can weight in.

Do you have an atm pressure sensor on your ECU? If so, plumb it to your intake and see if you're starting to draw vacuum on it.

As a data point, I ran a 964 plastic intake and it supported 100+ more wheel Hp than what you have.

Sound like you have a really nice build with that WHP number. What does your build look like?

I am pretty sure using the VRAM intake will work, there is some work to install it for sure. The big question is how much I can gain… I have about 72 hp pr liter now. If this is going to be worth it, I need at least 84+ (250+ WHP). The question is, am I able to do that by swapping out the intake (I guess the VRAM will give about the same max power as a standard 964 intake, but more torque along the way), changing cams to make more power on top and bit of porting? I would like to change out as little as possible at this stage, so no new cylinders, rods etc.

If there is only minimal gains to be had, I will rather enjoy the engine as is and do a more thorough (and more expensive!) rebuild at a later stage.

[PeteKz]

Consider the power and torque of the 3.6 993 VRAM versus the 993 without the VRAM, versus the 3.6 964 engine:

993 VRAM: 285 HP, peak at 6100 RPM; 251 torque at 5250 RPM.
993 base (w/o VRAM): 272 HP, 243 Lb-ft torque
964: 247HP at 229 torque at 4800 RPM

Someone who knows should chime in, but I believe the 993 uses different cams than the 964, so part of the power and torque gains are combined with a different cam. Interpolating the numbers, and reducing them 20% for your 3.0 displacement, I think you can expect about 10 HP gain due to the VRAM without changing the cam. Maybe 30 HP with the 993 cam.

I would stay with the 3.0 CIS until I was ready to do a new larger engine.

[JoeMag]

Originally Posted by storegnu

Sound like you have a really nice build with that WHP number. What does your build look like?

I am pretty sure using the VRAM intake will work, there is some work to install it for sure. The big question is how much I can gain… I have about 72 hp pr liter now. If this is going to be worth it, I need at least 84+ (250+ WHP). The question is, am I able to do that by swapping out the intake (I guess the VRAM will give about the same max power as a standard 964 intake, but more torque along the way), changing cams to make more power on top and bit of porting? I would like to change out as little as possible at this stage, so no new cylinders, rods etc.

If there is only minimal gains to be had, I will rather enjoy the engine as is and do a more thorough (and more expensive!) rebuild at a later stage.

My motor was a 3.8 motor. Hp was dynojet SAE5 correction. Was just referencing capability of the 964 plastic intake with single throttle. Though I've read that at my level you're starting to draw vacuum in the intake at higher RPM.

[stownsen914]

No results to share, but I'd think that if you go to a more aggressive cam, perhaps something like 993 Supersport (I think that's a 993 Cup cam?), a freer flowing intake like the 993, and a properly matches exhaust, you might get something like with PeteKz is suggesting. Maybe more if you spend some time optimizing the tune on a dyno.

Totally different setup, but I recall years ago that Bruce Anderson put Weber 46's and headers on an internally stock Carrera 3.2 and picked up like 30-40 hp.

[Bill Verburg]

1) the 993 intakes are sized for 3.6, the 993RS has a slightly different design from regular 993 for it's 3.8 and cam change. The internals shape and volume are important because these are resonance designs, The resonances will be different for a 3.0 or different cams

2)the vram boosts midrange torque on a 3.6, the torque curve is more hump backed like a camel, a 964/993 boosts at high rpm the torque curve looks more like a pouncing cat.

3) if going to all that trouble I'd start w/ ITB's then maybe use a 993 plastic nvr manifold if you want to tune for resonance effects Most of the built 993s are going w/ ITB's and a GT3 resonance manifold but the are all 3.8 and up. The GT3 resonance manifold is not too much different from the plastic 993 nvr in operation but is a whole bunch larger

[storegnu]

Hi, Bill!

Thanks for that bit of info, I really haven’t thought about that aspect. So in reality you think that the 993 VRAM or the 964 plastic intake might not be suited to a 3.0 at all? Shouldn’t the resonance effect only hit a little higher up in the RPM range on the smaller 3.0?

With regards to the torque curve, I prefer your pouncing cat over the camel, as the power delivery is more fun. The thing is that the 993 VRAM intake was available for a good price. And one more question as well about the 993 VRAM: I was thinking that the VRAM was a good as a standard 964/993 intake on top, but gave more torque along the way? My stock 911SC intake seems to fall off a cliff at 6500 rpm, how high up the rpm-register do the 964/993 intakes work?

[storegnu]

Originally Posted by PeteKz

Consider the power and torque of the 3.6 993 VRAM versus the 993 without the VRAM, versus the 3.6 964 engine:

993 VRAM: 285 HP, peak at 6100 RPM; 251 torque at 5250 RPM.
993 base (w/o VRAM): 272 HP, 243 Lb-ft torque
964: 247HP at 229 torque at 4800 RPM

Someone who knows should chime in, but I believe the 993 uses different cams than the 964, so part of the power and torque gains are combined with a different cam. Interpolating the numbers, and reducing them 20% for your 3.0 displacement, I think you can expect about 10 HP gain due to the VRAM without changing the cam. Maybe 30 HP with the 993 cam.

I would stay with the 3.0 CIS until I was ready to do a new larger engine.

Thanks. That would fall short of my target. Maybe complete rebuild is the only meaningful way to go to extract more power.

[mepstein]

Our philosophy is to build the engine from the bottom end out. Once you have a good base, you add the extras to complement and optimize the foundation. Going the opposite direction is usually a waste. You are fighting existing piston shape, compression ratio, cam design, etc.

[storegnu]

Originally Posted by mepstein

Our philosophy is to build the engine from the bottom end out. Once you have a good base, you add the extras to complement and optimize the foundation. Going the opposite direction is usually a waste. You are fighting existing piston shape, compression ratio, cam design, etc.

Thanks, I fully agree. The only thing is that going down that route means a total rebuild and that is quite expensive.

I am looking for a way to maximize what I have, plus changing intake, cams, porting and tuning. That keeps the costs reasonable.

[Bill Verburg]

Originally Posted by storegnu

Hi, Bill!

Thanks for that bit of info, I really haven’t thought about that aspect. So in reality you think that the 993 VRAM or the 964 plastic intake might not be suited to a 3.0 at all? Shouldn’t the resonance effect only hit a little higher up in the RPM range on the smaller 3.0?

With regards to the torque curve, I prefer your pouncing cat over the camel, as the power delivery is more fun. The thing is that the 993 VRAM intake was available for a good price. And one more question as well about the 993 VRAM: I was thinking that the VRAM was a good as a standard 964/993 intake on top, but gave more torque along the way? My stock 911SC intake seems to fall off a cliff at 6500 rpm, how high up the rpm-register do the 964/993 intakes work?

3.2 is also a resonance manifold, look at it's size compared to 964/993

You'd have to put them on a dyno to see how they all compare.

I agree the jaguar type toque curve is more enjoyable, I have both a 993RS 3,8 and 993 3.6 nvr, the RS is all all around far more powerful , but it's not as much fun to go to red line as the 3.6 nvr, both have the same cams and custom chips.

A buddy has a 4.0 w/ GT3 manifold and ITBs, it's also way more fun to rev to red line at ~8K+

[PeteKz]

If you are already getting 218 WHP on a 3.0 engine, that's pretty good. There are no easy mods left on your table to increase the power, without changing the cams, and that almost certainly requires changing the pistons. And so it goes...

There's an old saying in racing: It's more important to make the driver faster than to make the car faster.