Rebuilding a 3.0l SC as a turbo

[flat6pilot]

I’m looking for advice on a few 10,000-foot decisions with my 3.0l SC turbo rebuild. I’m not looking to find a core from a 3.2 or 930. I think the hp goals should be reasonable for my 3.0SC core.

Goal: <=450 WHP. Be able to run full power on the street but be able to turn the power down below 400 for track days. I only do about 3 or 4 per year.

I currently have:
• 3.2 Carrera Manifold
• Garrett GT030R Turbo
• Megasquirt II

Planned changes:

P&C:
• Mahle 98mm 7.5:1 P&C set – ($4500)

Rods:
• Carrillo Rods

Cams:
• Regrind SC cams to 964 profile

Heads:
• Upgrade valve springs, retainers, and guides.
• Twin plug
• Port match (within reason) to the Carrera manifold.

Additional planned updates:
• 964 Oil Pump.
• Upgrade case oil squirters
• ARP head studs.
• Refurbish the crank (machine out the oil plugs to truly clean it.)
• Upgrade intercooler
• MS3 Pro for full ignition control.
• Add knock control (I think MS3 can only handle 1 knock sensor input)
• 930 4-speed w/ LSD (Stock gearing, planning to drop 3rd and 4th down for better drivability on track)


Kyle

[TurboKraft]

Smart, and should allow you to easily achieve your goals.

Mahle P&Cs should get you where you want to be, as will the cams.

Stock rods aren't light, but they're plenty strong, especially rebuilt with ARP hardware.

[Tippy]

Camgrinder can grind your SC cams to 993SS for a really affordable cost and I believe the stock valve springs and hardware can stay 100% stock. 3.0 rods use larger rod bolts than the 3.2 like I have, so I wouldn’t see a problem using stock rods (after resizing big end and rebush little ends) using ARP bolts.

[flat6pilot]

Thanks for the 'reinforcement' replies.

I think I'll go with the turbo Mahle 3.2l P&C's and possibly Carrillo rods if I decide. I still have time...

Will be pulling the motor in a few weeks to send to a local builder. I'm trying to get a few of the big $$ parts ordered ahead of time.

[matthepcat]

Hey Kyle, interested to hear how it goes. Keep us posted.

[Axel84]

following!

[flat6pilot]

I'm beginning to order parts.

Question for the engine building guru's:

I'm ordering a set of Carrillo rods. They have an 'upgrade' option to get CARR bolts which are good for 8500rpm. Is this legit or should I go with ARP's?


CP-Carrillo Connecting Rods Set for Porsche 3.0 Liter with 3/8 CARR Bolts
$2,479.08In stockSKU: PR-3.0>-65030S

CP-Carrillo connecting rods are fully machined from a proprietary 4330m alloy forging for strength and durability. Rods are available with 2 types of bolts: The standard WMC-H7 (H11) bolt with a UTS of 220ksi and our upgraded CARR-S7 (MP35N) bolt with a UTS of 285ksi. The CARR upgraded bolt is a good choice if planning on revving the engine higher than 8500rpm. All our bolts are manufactured with asymmetrical threads, each thread has a slightly different design than the previous giving the bolts an evenly distributed thread engagement. This helps increasing the clamp load and fatigue life of the fastener.

[Tippy]

ARP has a very long reputation of being pretty good.

[TurboKraft]

Over the years, we've sent in several sets of Carrillo rods for inspection and testing, rods that came out of engines we did not build. Bolts are tested for stretch to see if they've gone "plastic," i.e. permanently deform when torqued to value. Every set of rods with WMC bolts ended up getting new bolts, while only twice have we had to replace CARR bolts -- and those two engines were sorely abused.

Here's what Carrillo told us decades ago:

WMC bolts are adequate for most applications, and can be torqued approx. 2-3x before you have to replace replace them. It is essential to keep a log of the pre-torque length and measure every time.

CARR bolts are the best, and can be reused over and over -- if they have not been stretched from over-torque or over-rev.

We always measure both stretch and torque, and not once have we had a CARR bolt deviate from the published target torque value in order to achieve proper stretch.

We only specify CARR bolts.
a) buying them 1x costs less than buying WMC bolts twice
b) like good valve springs, they seem like inexpensive insurance in the event of an over-rev
When failure usually results in catastrophe, it doesn't seem like a wise place to save money.

[Ollies930]

Chances are your valvetrain will give up before 8500rpm and the real benefit for CARR bolts is the fact that they can be reused multiple times. If that is not a necessity for you, then you might as well spend your money on other things and go with the regular ARP bolts (which are very good quality). With stock SC cams, your peak hp will probably be in the 6200-6500rpm range anyways.

[flat6pilot]

Originally Posted by TurboKraft

.. while only twice have we had to replace CARR bolts -- and those two engines were sorely abused.

...CARR bolts are the best, and can be reused over and over -- if they have not been stretched from over-torque or over-rev.

We always measure both stretch and torque, and not once have we had a CARR bolt deviate from the published target torque value in order to achieve proper stretch.

We only specify CARR bolts.
a) buying them 1x costs less than buying WMC bolts twice
b) like good valve springs, they seem like inexpensive insurance in the event of an over-rev
When failure usually results in catastrophe, it doesn't seem like a wise place to save money.

Thanks Chris! That's the explanation I was looking for!

[flat6pilot]

Moving forward.

P&C's (10-week delay), rods, rod bearings, on order.

[VW 612 RS]

Would recommend to change oil squirters from 0.8mm to 1.2mm and turbo oil pump.
That what RUF did on the basic 3.2.
You need to cool down the piston more on a turbo engine.

This is some don't think of but its very important

[flat6pilot]

Originally Posted by VW 612 RS

Would recommend to change oil squirters from 0.8mm to 1.2mm and turbo oil pump.

Yes, that's part of the plan. The motor is apart now.

This was the issue: (#4 piston) The cylinder wall had light scoring but otherwise ok. I didn't find any glitter in the oil or anything on the magnetic drain plug. ??



UPS says the Mahle P&C kit is showing up today. Only two weeks, not ten!

[quattrorunner]

Sweeet

[feraripeter1]

Have you try changing oil squirters from 0.8mm to 1.2mm and turbo oil pump

[mikedsilva]

Any updates to your build?

[flat6pilot]

It's moving forward. Crank is out getting machined but should be back this week. Sent the cams to Dougherty to regrind the SC to a 964 profile. Rockers were sent along with them to get refurbed. The cams came back last week.

Once the crank is back we should be able to start assembling the case.

Heads and Carrera intake was lightly ported. Otherwise, the heads are still on hold as we line someone up to do the twin plugging. Then on to fire-ringing then off to new valves, springs, retainers.

I'll be stopping by the shop this Thursday to check in.

[mikedsilva]

Did you elect to go with the 7.5:1 compression?

I'm mentally gearing up to rebuild my SC turbo conversion.. currently using 9.5:1 Max Moritz style in 97mm turbo barrels.. I wont be changing the gearbox so the 915 will be the limiter.

If I twin plug my heads and use a 964 cam (slightly more overlap), do you think I can still use the 9.5:1 compression ? I like the car to be quite drivable off boost, and am worried that much less than 9:1 would make it feel pretty sluggish?

[flat6pilot]

I did. 7.5. The stock compression was 8.5 and did well at around 10psi, until it didn't. I beat on it pretty good for about 8 years.

I know 9.5 compresson has been done, but you'll need to be careful with timing and boost. At that level, knock sensor(s) control or at least monitoring would be advised along with twin plugging for added safety. Boost will add to your compression ratio dynamically. With 10 psi, your dynamic CR could be above 13 compression. I'm no expert though, I'm sure others will chime in with better advice.

I need to check into the shop this week to see if there's been any progress on the lower end and find out where we stand on the heads. (Who's twin plugging, fire-ringing...etc.) Otherwise, nothing new to note so far.