3.0 SC HP Expectation - post modification
 

I was hoping someone could provide some clarity on some mods I am planning.

I've looked at various options but one that stood out (largely based on $$$) was to do the following:

1. Maintain cylinders so therefore retain as 3.0
2. Switch CIS to Weber 40mm
3. SSI's (or early headers)
4. Sport muffler
5. Cams (not sure which ones at this stage)
6. JE Pistons (10.5:1)

What is a reasonable HP expectation out of this?

The car is to be used for street driving only. Ideally I am hoping for around the 260-280FWHP. Any ideas on what torque I can expect?

Do I need to do anything else (ie. porting) to get these sorts of HP numbers?

What is the HP limit of the 40mm carbs? I would like to know at what point should I consider the much more spendy option of 46mm PMO's.

Thanks.

That seems a little high. remember there is no greater HP mod than more CC's. Adding dual plugs would help with higher compression, bigger webers, headers, a better ignition/ curved distributor. That would bring you closer to ~260. The list is endless!
If $$$ are #1, than stick with ROW stock pistons (9.8:1?), good carb cams, weber 40,s, headers/no heat and lighten up the car.

Thanks James. What sort of HP do you think I would expect with that combination?

I am not totally governed by the cost but I do try and think about cost/benefit.

My 3.0L was dynoed on a MAHA rolling road last week.

It features 10,5:1 JE pistons with single ignition (ROZ 100 gas is available at German gas stations), cams similar to GE60, early 'big port' SC heads, Dansk 1 5/8" headers with dual pipe 'barrow type" exhaust and 40 Webers with 36mm venturis.

We came out at @241 HP at the flywheel at 6,7k RPM - power started to drop of at 6,9k RPM. Torque figures were at @214 ft-lbs at 3,8k RPM.

With twin plug ignition and some additional work to the case, cylinder mooning etc to reduce windage losses 250FWHP MIGHT be reachable here.

Best,
Christian

Be careful...With today's pump gas, 10.5 CR will lead to detonation if you don't twin plug. Also, 40mm Webers will be too small if you have any head work done.

Here's some results from my 10.5 CR 3.0 twin plug.

http://forums.pelicanparts.com/porsche-911-technical-forum/246563-another-rsr-clone-project-dyno-day.html

Thanks Christian - just the sort of info I was after.

That's a great result. I was wondering if 40mm were too small. I guess I need to firm up my HP expectation and go from there. It seems that I can get 240 with 40mm. If I want more then 46mm is the answer.

I retained the stock Mahle 95mm cylinders for my build with JE 10.5:1 pistons. I used GE 60 cams, 46 mm Webers that I bought for about the same price as a good set of 40s and twin plugged the heads. The only dyno time is seat-of-the-pants. I was told that this combination would be "peaky" and hard to drive on the street. I was also told that there would be little difference in power under 4,500 rpm.

This motor is a torque monster and will rev to 8,000 like a light switch. It's a blast to drive. It's very, very streetable and cruises at 70 like a stocker. I have one issue I haven't sorted yet with the just off idle to 2,000 rpm stumble. There's a transition that the current carb set-up doesn't like but I'll get it fixed.

I don't think you'll like 40s with GE60 cams; they run out of breath too early. Save your money and get the 46s and for sure dual plug your heads.

Lindy

The 3.0L with 40 Webers and the modifications mentioned above does pull very strong from 2k RPM in 4th gear all the way up to 7k RPM. The cams do kick in additionally at around 3,9k RPM but it is definately very driveable from idle.

With ROZ 100 gas available here in Germany 10,5:1 is reasonable with single-plug and taking the relatively low dynamic compression due to the profile of the GE60 cams into account.

Best,
Christian

Christian,

You're right about single plugs and 100 octane fuel but the biggest benefit to twin plugs is being able to add lots of advance and still have the motor live. If you run stock timing it's not an issue but this combination likes lots a timing (36 degrees total in at 3,500 rpm). The difference between 36 and 26 (stock) is incredible. You can't do that with single plugs except for about 30 seconds.

Lindy

LOL love it Lindy! BTW, love your engine build.

Thanks Lindy. I have been watching your rebuild with keen interest. I'd say you have confirmed the need for 46mm and twin plug. If you get some more carbs at that price let me know :D

...and it makes a lot of fun to drive ;)

This may not help but this is what I have...

3.0 79
Ported heads,
SSI's Blended to heads + 2/1 Monthy
10.5:1 JE's
Dual plug
ITB's
EMS ECU
GE80 like cams,
Raceware springs (stock retainers)
ARP rod bolts,
spinning to 7,200 ( built for 8k but for street longevity reasons limited )
Lightened flywheel/ race clutch

204 RWHP......great to drive on the street...heaps of torque low down but all the power after 4k. Only issue is the flywheel makes it a bit jolty in traffic.

I though the HP would be higher but I am not prepared to do any more work at this time.

Mark..........

Tom Sch helped a lot on tuning my 3.0L (thanks again for that!) - and was one of the first who actually drove it. Check out his awesome 3.2L build!

@lindy 911
With dual plugs you can of course advance timing to the numbers you have mentioned. Considering the somehow 'budget' orientated approach this would have fetched another $2,5-3,0k for the subject build and it runs very well on single plugs with the high octane fuel available here in Germany.

Best,
Christian

Dude the oil prices are down because they want us to buy their christmas retail and day after thanksgiving crap-once the x-mas rush is over-hello 3.00/gallon

Anyone car to guess at what Jhon Smitch is talking about?

Lindy

D911SC,

There's a set of brand new DC 60 (GE60) cams for sale here for $500. Here's your budget start. Jump on them and we'll start looking for carbs and other parts. These are $900+ new.

Lindy

Thanks Lindy, I saw that and your comment convinced me to go for them. I am not sure if seller is willing to ship to Aus but I have asked anyway. Fingers crossed!

Maybe but with a similar build, twin plugging and LOTS of EFI tuning I topped out at 240 fwhp. Good luck.