Bill Verburg

Again 'cup cams' is vague considering that this is a 964 forum.
all durations are @1mm lift
964Cup used the same cams as 964RS and street 964
964 cam specs I duration 240(.470"lift), E duration 230(.430" lift), timing 1.25mm

SS cam specs I duration 256(lift .4905") , E duration 245(.452" lift), timing 1.55mm

993 Cup cam specs I duration 248(.492" lift), E duration 234(.452" lift) timing 2.0mm

The SS cams are near the edge of where ITBs are needed, note that factoru 993Cup did not use ITBs but also did not use the 993 street car MAF sensor or the 964 barndoor senso, rather they used MAP and TP sensors for control w/ a wide open air path

964/993RSR cam specs I duration 280(lift .492") E duration 264(.492" lift) timing 4.6mm

Lobe centers of course are different and also affect how the cam behave in an engine, the 1 # that is most telling for comparison purposes is the timing
mild is low, wild is high

cobalt

Are you talking to the wheels or crank? My pretty much bone stock 3.6 with exhaust & intake mods achieves 290 BHP and 280 torque on a 90 degree day.

cuse92

Honestly, I find it pretty astonishing that you could get an extra 40bhp and 52 lb ft over stock with just exhaust and intake mods (even at the crank). My car has a 3.8 with a custom H&S exhaust with no cats and a 3.8 and doesn't make that kind of torque at wheels or crank. My car made 308bhp and 264 lb ft at the crank (well, on a dyno it is measured at the wheels and then a crank calculation is made), Frank's Black Betty with a 3.8 and everything he's done to it made higher HP and similar torque numbers to mine.

I had the exhaust put on before I had the 3.8 build (and the RS holes drilled in the airbox and a K&N filter) and it gave me roughly 12bhp and my torque actually dropped a bit. And these readings are all at temps much lower than 90 degrees F (those temperatures occur in England about once a generation).

There's been lots of threads on RL on the accuracy of and huge variances in dyno readings. The differences we are talking about may be just that.

As to the cup cams from a previous poster, they are factory 993 Cup cams, I don't have the I/E duration specs on me at the moment but I don't think that is the point of this thread anyway.

I love my car and am happy I did it, but the OP I believe wanted to know whether it was the best bang for his buck. My opinion, having spent the cash to do it myself (and therefore feeling well-placed to give my honest opinion), is that it is not the best value for money, even if you don't use all Porsche OEM parts like I did. If you guys think it is, that is your opinion and is just as valid. But to me, if you are comparing the various ways you can improve your 964's performance and are on some sort of a budget, there are other things you can do that are better bang for your buck. Lighten the car, chip, LWF, upgrade exhaust, go on a diet, get driving lessons, etc. If you've done all those and still aren't satisfied, go for your life on the 3.8 but get your wallet ready and don't expect it to be transformative over the other bits you've already done. Anyway, one man's semi-solicited opinion!

ras62

Cuse92 If looked at in a slightly different way why would you be astonished that such a small capacity increase can produce negligible differences between engines? I have said before, there are many other factors that have a bigger effect on the numbers than a simple 4% increase in capacity.
There are many 3.6 cars with standard internals producing 290-300+ bhp @ crank. It's really nothing unusual and why imo the 3.8 conversion is a lot of money for not much benefit, especially so when done in isolation.

KaiB

Alright ya'll!!!

While it's certainly fun to discuss, argue and compare horsepower and torques, let's all remember that dyno figures are relative to the instrument used, the conditions under which the test was undertaken and often inexact.

Which figure, for example, would we use to back calculate crank horsepower from wheel? Is 15% a good number?

If it is, then my little engine produces 355 bhp...

Meaningless....

cobalt

I agree, I wasn't trying to ruffle feathers just trying to get a better understanding what a 3.8 conversion vs turbo would do for me. I am working on a race motor. I currently have a 993 varioram engine I am not sure what direction to head. i have short gear 6 speed box but would prefer to stay N/A although the low boost turbos I have driven are amazing. Constant pull with no lag. I expected to see higher torque numbers given the larger displacement. Of course the curve means a lot too. I hope the Op will appreciate the banter and I meant no slight towards cuse92.

Yes 15% is usually the standard drive train loss this was info I have been using provided by Rick DeMan.

I feel my numbers to be rather accurate. I had two cars dynoed that day on the same unit, my stock 928 GTS and my C2 with the mods listed. The GTS was dynoed previously on a dynapak with similar results and both the GTS results are very close to stock (350BHP 370 tq). So I am guessing I can rely on these numbers as close to accurate.

Am I reading these charts incorrectly? If so please correct me. First is the GTS the second is my C2. Sorry for the bad photos of the charts. I was supposed to be sent better charts their ink had run dry but never received them.

dave964diver

A 3.8 in isolation offers little benefit. - correct. And a lot of money for a small increase. If your PC are glazed and tired as mine were. And at the time I had the finances to offered all the other complimentary necessaries to exploit this increase in capacity. Then it make sense.

I still spent the thick end of 17k doing everything I possibly could by myself.

Think we're going around in circles here. Bottom line is what can you afford.

KaiB

Nah Tony, it's all good.

If you're building a race motor please think long and hard about the class you intend to run. I believe you're already headed for the GT classes if you want to race with the PCA.

If that's the case, a N/A engine is ABSOLUTELY the way you want to go, and you may want to keep a 3.6 to run with GT4 at 2677# driven; a 3.8 will run you up to around 2877# driven and the monster cars in this class who run 3.8s are developing in excess of 410hp.

At GT3, all bets are off!

crg53

I don't want to hijack this thread, but all this talk of HP and Torque had me thinking. Has anyone done a 964 3.6 with Varioram, 993 HE and Motec, and if so what was the outcome. In my mind this combo should show some decent increases across the board, for a reasonable amount of $$$

cuse92

Please re-read what I wrote - I didn't say I was astonished at the negligible differences because of small capacity increases. I said that I was astonished at him getting a 40bhp and 52lb ft increase on a 3.6 from just intake and exhaust mods (I also said that I didn't think the 3.8 was best bang for the buck even though I did it myself). I've done intake/exhaust mods on lots of cars, including the 4 n/a 911s that I've owned, and I don't think those kind of increases happen without a chip, other mods, and maybe a helpful dyno. Talking about figures on RL is silly anyway because it depends on the dyno, but I was just responding to the poster who seemed unimpressed by my 3.8. Trust me, it has way more torque than my nice 3.6 had with intake mods, custom non-cat exhaust and Steve Wong chip, regardless of what the dyno says. But I paid a lot of money per bhp and lb ft so again not best bang for the buck. All IMO and not trying to start anything.

ras62

Perhaps we are talking at cross purposes. The 40bhp increase you mention is in fact quite normal on a base engine but with a good remap not just intake and exhaust mods. Think about your engine having +60bhp or 25% more from a cam and extra capacity and both figures look reasonable. As I said in an earlier post I have seen rebuilt standard 3.6 engines produce even more than your car, it just depends upon the skill of the guy doing the build.

Bill Verburg

Do a search on Geoffrey Ring and/or 9M(aka 9 Meister) both have built remarkable 3.6 motors and remarkable 3.8 motors,Geoffrey lives near me so I've had the pleasure of riding in his masterpieces, they also built the original run of Singer motors

Bill Verburg

As to dynos and inflated #s it' a fact the numbers from 1 cannot be compared to the #s from another even w/ correction factors

The only dyno that that I will use and believe is a DynaPack, we are blessed in the NE w/ several of these and the #s in the comparison chart I posted above are both uncorrected rear wheel torque measured on a DynaPack

Brideyo

I'm liking this ......

cuse92

It all depends on the dyno you are on. After spending a huge amout of research, time and money modifying a lot of cars, I just don't believe that "standard" 3.6 engines can do 310 bhp plus at the same ambient conditions/measurements/dyno that produced 247bhp in the factory car, even with the most awesome engine builder in the world. Particularly while getting huge torque increases at the same time. My 3.8 was built by one of UK's top builders with no expense spared, as was Franks, which is a 3.8 modified absolutely to the max with custom everything, aggressive cams and Motec to get to a bit over 340bhp (and the same torque as mine). Motec would make a difference on bhp for mine, but it is another £5k plus I don't want to be hunting for Shell stations every time I go for a long drive so despite good advice from Colin I'm not doing it (for now). But that takes me even further from the standard 3.6's that you and others seem to be seeing mad numbers from.

Anyway, I think we are at least agreeing on one point, which is the main point of the thread. Using same amount of money as just a 3.8 for 3.6 mods (which it is agreed will improve the engine over standard) plus lightening car and upgrading suspension and brakes, is better value for money than a 3.8 IMO.