3.0 SC HP Expectation - post modification

[haycait911]

here's mine. dead solid dependable and pulls like a truck. nothing exotic, but it works. don't get to focused on big HP at high rpm's. torque is what get's it done. I've got stock 34mm ports and 34mm venturis in weber 40's.

3.0 dyno day - a pleasant surprise

[D911SC]

That's a great looking dyno sheet haycait911. Any hints on what that 'secret cam grind' is???

[haycait911]

Originally Posted by D911SC

That's a great looking dyno sheet haycait911. Any hints on what that 'secret cam grind' is???

details here:

Dougherty Racing Cams - my experience

the engine pulls amazingly. I've done some more accurate 0-60 times and they're in the low fives. could shave a little yet but I'm unwilling to dump the clutch at launch.

YouTube - 004.AVI

also went drag racing

took my SWB drag racing today.........

[D911SC]

Originally Posted by lindy 911

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

Tried to buy them but seller won't ship to Aus. I'll keep looking - thanks for the heads up.

[haycait911]

FWIW D911SC , I would be inclined to put together the rest of your package, pistons, crank, heads, induction, before buying the cam. the cam can be tailored to whatever setup you come up with. it has the most flexibility compared to everything else.

[snbush67]

I wonder if these twin plug heads are still availible they would make a nice addition to your build, plus they have the beefier springs and retainers allready installed with your euro pistons and the shaved heads it is likely you will end up with around a 10:1 CR. Or you can order custom J&E pistons once you measure everything.

FS: 3.2 Cylinder Heads Twin Plug

Shane

[D911SC]

Thanks Shane. I'll have a look at these.

[D911SC]

Originally Posted by haycait911

FWIW D911SC , I would be inclined to put together the rest of your package, pistons, crank, heads, induction, before buying the cam. the cam can be tailored to whatever setup you come up with. it has the most flexibility compared to everything else.

Thanks again haycait911. It does make sense to do it this way.

[D911SC]

Just took delivery of Wayne's book today - no guessing which chapter I am reading first!!

[snbush67]

These may or may not be the optimal cams for your set up but they are in Australia and are new billet web cams 964 grind. At 600 bones you may be able to barter and get them down to 500. At least you will save on shipping.

For Sale: Billet Cams to suit 2.7, 3.0 or 3.2

Shane

[D911SC]

Originally Posted by lindy 911

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

I managed to get these ones. Despite advice to get cams last I have read alot of good things about these - not the least your own comments Lindy.

At this stage I have revised my build to be:

1. 3.2SS using JE 98mm 10.5:1 (purchased)
2. GE60 cams (purchased)
3. PMO 46mm (what the heck, I'll just go top shelf!)
4. SSI (ordered today)
5. Dansk 2 in 2 out
6. Upgraded rods (not sure which ones yet - open to advice)
7. Single spark (researched this and in Aus we have the fuel to cope with 10.5:1)

No doubt they'll be a few extras.

If anyone has any spare PMO's or 98mm cylinders floating around I'd be interesting in hearing from you.

[Mark McClure]

I know, as soon as you have dual plug you then need all the bits to drive it again the price goes up. Even with higher octane fuel without a knock senor you may be risking the whole engine. Dual plug is insurance, admitedly not cheep, but worth concidering....or put an ECU in there with a knock sensor to retard the ignition if needed.

Otherwise spending money and building a motor that you can not get all of the benefit from is a leaving a lot on the table.

Mark........

[lindy 911]

D911SC,

Your motor will be a rocket but the omission of the twin plug, I believe, is a mistake. If you sourced a used set of 46 Webers you could use the saved money on a Rennwerks 12 wire distributor and MSD ignition to fire it. 100 octane fuel is marginal with 10.5 : 1 and you need a safety buffer at high RPM.

One thing to remember is that this combination likes timing and lots of it. 30+ degrees of total timing is not uncommon with the DC 60 cams. The timing really wakes the motor up above 4,000 RPM. You're almost there, but I sure would hate to see you melt a brand new 3.2 SS.

Lindy

Oh by the way, your stock rods with ARP or Raceware bolts are good to about 7,000 RPM. Have them re-sized then re-bush the pin end. I like Raceware because of the ease of installation; they do not require a stretch gauge and use a torque wrench.

A good source for most of this is Arron Burnham @ Rennwerks in Camarillo, Ca. 850-240-6931

[kent olsen]

Here's my 3.0L rebuild.

81 3.0L ( small ports)
John Dougherty GT2-102 cams
JE 9.5:1 pistons
40mm webers
Heads drilled for twin plug
European headers
M&K 2 in 2 out sport muffler w/baffles

On J&B Racings engine dyno it made 245hp/228lbs torque on twin plugs.
With single plugs it made 233hp/217lbs torque.

This was turning the engine to 7200rpm. HP peaked around 6800rpm torque around 5600rpm.

[Jeff Higgins]

Originally Posted by lindy 911

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

Actually, the advantage of twin plugs is in running much less advance and still getting the charge to burn completely. That's the whole idea of lighting it from both sides. Most of us run around 25-26 degrees total with twin plugs at about 10.5:1 to 11:1 compression.

Cranking the total advance on a twin plug motor up to 36 degrees will soon ruin it through severe detonation. You probably won't even hear it until something expensive lets go.

[D911SC]

Originally Posted by lindy 911

D911SC,

Your motor will be a rocket but the omission of the twin plug, I believe, is a mistake. If you sourced a used set of 46 Webers you could use the saved money on a Rennwerks 12 wire distributor and MSD ignition to fire it. 100 octane fuel is marginal with 10.5 : 1 and you need a safety buffer at high RPM.


Oh by the way, your stock rods with ARP or Raceware bolts are good to about 7,000 RPM. Have them re-sized then re-bush the pin end.

Thanks for your comments - Lindy, Mark Kent and Jeff. As the response is to twin spark I will need to consider this. I can't ignore good advice. I am not rushing this rebuild so I can save up the extra $$ and do it then. The last thing I want it to leave a pile of bits on the road as I destroy my new motor.

I have a couple of questions. For twin sparking I need a new 12 wire distributor and MSD ignition. As well as drilling the heads is there anything else to do?

Also, is it also worth considering new rods rather than stock? With the DC60 do I need to try and get more than 7000 RPM's? Again the last thing I want to do is break something due to bad planning. I am trying to make a fast but strong/reliable engine.

[Jeff Higgins]

Nothing else to do on the ignition. Don't forget to drill the lower valve covers as well.

Depending on the angle of the second plug, it may interfere somewhere. Some guys drill and tap for the smaller plugs to avoid this. I drilled and tapped for standard, full size plugs, and mine interfered with one of the head stud nut. Replacing the barrel nut at that one position (per cylinder) with a hex nut solved that problem pretty easily (the barrel nut was tall enough to hit the plug, the hex nut is shorter).

I fire mine with an Electromotive set-up. It's just matter of personal preference - the cost is about the same as a dizzy. I like the lack of moving parts and programability. No one can argue with the "cool factor" of the dizzy, though. Just two different approaches; both work quite well.

Like Lindy says, Your stock rods are fine for 7,000 rpm (or more, actually) even with stock bolts. ARP or Raceware provide that insurance factor for over-rev, and a lot of peace of mind. Stock rocker arms are the limiting factor in these motors, not the rods. You'll be fine. I've been running my stock rod / ARP rod bolt combo for a couple of years and dozens of track days. I'll usually shift at 6,800-7,000 rpm, but have been known to take it to 7,200 on occasion. I pulled the top end off after about a year or so, and the rod bearings looked brand new.

[PFM]

Jeff,

Why do you say the stock rockers are the limiting factor versus the stock rods. I think this may be the first time I have heard that one. Stock springs yes limiting. With good springs and Ti retainers I do not see the rockers being an RPM limiter. Please expand on the thought.

Regards,

PFM

[Jeff Higgins]

The stock rockers are designed to break in the event of piston to valve contact, like if a tensioner fails and the chain skips a tooth, or in the event of a serious over-rev (the infamous 5-2 downshift, missed shift, or something like that).

High lift cams with abrupt ramp angles that accelerate the valve very quickly, coupled with the heavy springs required to keep the whole works from floating under those conditions, will sometimes exceed this designed-in yield strength. With a big enough cam and heavy enough springs, this happens before rod bolt strength or rod strength becomes an issue.

[PFM]

Jeff,

Thanks for that bit of input. I have had the miss fortune of testing the break away design you speak of in a friends car. The reason this has me scratching my head is the lack of aftermarket rockers for these engines to overcome this problem. My cams are not that radical nor spring pressures that high. I would like to hear from CamGrinder on this thought as well. I did detail the rockers and sent them out for cryogenic treatment. If the pistons and valves kiss in this build something else broke first.

With a well prepped set of Porsche rods and Raceware bolts what RPM do you think they are good for?

Regards,

PFM