Rebuilding a 3.0l SC as a turbo

[mikedsilva]

Originally Posted by 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.

Thanks for replying... that's interesting about the 8.5:1... were they the stock cast Mahle pistons? If so, the 8.5 that Porsche claims is usually closer to 8:1...which makes me think the 9.5 is not a 'great' idea at all, even with twin plugging.

[flat6pilot]

Yes, I'm pretty sure they were stock cast.

You can calculate dynamic compression here:

https://www.rbracing-rsr.com/comprAdvHD.htm I believe the 964 cam inlet closes @ 72° ABDC. I might have exaggerated the dynamic compression calculation, but you can try it yourself.

[flat6pilot]

So the project is lightly being held up finding someone to do twin-plugging on my 3.0l heads.

Question: I found these 3.3 930 turbo heads on eBay that have been rebuilt and twin plugged already. Would they work on my 3.0l motor?


Porsche 911 turbo Carrera 3.0 Cylinder Heads twin plug Fully Refurbished 930 3.3


https://www.ebay.com/itm/124530804835?itmmeta=01HV2BN4JNFNBDNBCZSB9SEHTS&hash=item1cfe9d4863:g:4NEAAOSwV~NgAxDM

[mikedsilva]

Originally Posted by flat6pilot

So the project is lightly being held up finding someone to do twin-plugging on my 3.0l heads.

Question: I found these 3.3 930 turbo heads on eBay that have been rebuilt and twin plugged already. Would they work on my 3.0l motor?


Porsche 911 turbo Carrera 3.0 Cylinder Heads twin plug Fully Refurbished 930 3.3


https://www.ebay.com/itm/124530804835?itmmeta=01HV2BN4JNFNBDNBCZSB9SEHTS&hash=item1cfe9d4863:g:4NEAAOSwV~NgAxDM

Those ebay heads look excellent. Wish we had stuff like that for sale over here.!

Have you tried to contact Craig Garrett to do your heads?

[flat6pilot]

Craig Garrett? Ohh...CGARR here on the forums... I haven't. I'll look him up.

[flat6pilot]

Progress has been slow. But we're creeping forward. Got the heads back from Craig. (They look fantastic!) I'll be upgrading the stock springs to the AASCO springs and retainers (Good to 8000k, for 'insurance') Rev limit will be set at 7k. The 964 cams run out of steam at 6500 anyway but it doesn't hurt to have a cushion.




I still plan to to the Niresist Rings (flame rings).



I have 98% of the parts in place. Once the heads are finally sorted and ready, it should be mostly assembly from here out.

Case was being sent out for proper cleaning and we should be able to get the bottom end started.

Hopefully just a few weeks out before things start happening.

Oh, I also decided on new 3rd and 4th gear ratios for the 930 4-speed.

I've already purchased and received thru Matt for 4th gear (Guard Transmission) and RetroSport for 3rd gear availability.

[flat6pilot]

It's been super slow progress. Heads and cylinders went out to get Fire Ringed, should be back from the machine shop soon. Shortly after getting them sent out, the bottom end began to go back together.

Then the first snag appeared: The bearings were outside the range by .004". (Loose) The option is to get the cases bored and back into spec. I need to check in with my builder this week if a shop was found to do the work.

Otherwise, we're technically on the downhill side of things with it going back together. Once, the motor starts to go back, the transmission re-gearing will follow shortly after.

Hopefully I'll have enough time to get it back in the car and running before the rain starts again in the PNW.

[gsmith660]

Wow we are pretty much on the same path.

[flat6pilot]

Originally Posted by gsmith660

Wow we are pretty much on the same path.

I'm not alone!

Chris (Turbokraft) called me right after I posted this and said the fire ringing is done. So the heads and cylinders should be coming back soon for hopefully the last time.

[flat6pilot]

With the EFI system, do I need the fuel acccumulator, or can it be removed?

[mikedsilva]

Originally Posted by flat6pilot

With the EFI system, do I need the fuel acccumulator, or can it be removed?

I left mine on for laziness and also incase I needed to put my CIS motor back in...

However on other cars that I ran efi, I removed it and just run the filter.

[flat6pilot]

Turbokraft is sending the heads and cylinders back from getting 'flame ringed'. Also getting performance springs for the valves to give me a safety margin.

We also have a solution to the case clearance. We were going to send it to Competition Engineering, but opted to get the bearings coated (need .004") instead. Using Line 2.
https://www.line2linecoatings.com/

This was the last thing in the way for re-assembly of the engine.

[decisive1]

Which EFI system did you end up choosing?

[mikedsilva]

Originally Posted by flat6pilot

Turbokraft is sending the heads and cylinders back from getting 'flame ringed'. Also getting performance springs for the valves to give me a safety margin.

We also have a solution to the case clearance. We were going to send it to Competition Engineering, but opted to get the bearings coated (need .004") instead. Using Line 2.
https://www.line2linecoatings.com/

This was the last thing in the way for re-assembly of the engine.

This is an interesting potential solution to your problem of excesssive main bearing clearance. Hoping you share the results. I'm a little skeptical but keen to learn.

[flat6pilot]

Originally Posted by decisive1

Which EFI system did you end up choosing?

I haven't completely decided on EFI. Currently leaning to upgrade to MS3PRO (Currently using MSII, fueling only)

I've been looking at Haltech Elite 2500 (or 750) Mainly because it has knock input available. The 750 doesn't. But I could go down the rabbit hole with you guys about needing are not needing knock control. I'm open to comments.

MS3 might be an easy transition and it's a bit cheaper, and has knock control available if I need it. I also know it pretty well as I've been using it for about 10 years on both the NA and Turbo version of my motor. Never had any issues.

Whatever I decide on, I'll eventually go full fuel and ignition control. I'll be adding a cam sensor and TPS to the mix.

I was just at the shop today and they have the bottom end going back together. We've run into another hopefully minor snag of the #8 bearing being too tight. They're verifying the part number. It's possible it's oversized but need to confirm.

Otherwise it's starting to go back together.

[gsmith660]

I have MS3 and love it. Want to go to COP eventually but will stay with EDIS for now until I have issues.

[mikedsilva]

Originally Posted by flat6pilot

I haven't completely decided on EFI. Currently leaning to upgrade to MS3PRO (Currently using MSII, fueling only)

I've been looking at Haltech Elite 2500 (or 750) Mainly because it has knock input available. The 750 doesn't. But I could go down the rabbit hole with you guys about needing are not needing knock control. I'm open to comments.


Whatever I decide on, I'll eventually go full fuel and ignition control. I'll be adding a cam sensor and TPS to the mix.

I

I believe Haltech have just released a newer version the nexus which has onboard wideband now.. (finally).
You're this far in, may as well fit a knock sensor (or two). I would imagine it's even more necessary on a turbo engine?

[Dr J]

I would agree with Mike. Having the knock sensor gives peace of mind and may allow you to tune a little more aggressively while protecting your engine. I did it on my EFI conversion and don’t regret it for a minute.

[decisive1]

I have been looking at the ECU Master Classic which does have knock control capability and on board wideband input, plus the usual goodies. It seems to be a good value.

https://ecumasterusa.com/products/ecumaster-emu-classic?utm_campaign=gs-2020-03-04&utm_source=google&utm_medium=smart_campaign&tw_source=google&tw_adid=&tw_campaign=18314156523&gad_source=1&gclid=Cj0KCQjwyL24BhCtARIsALo0fSDPrLHue8lgQD6QKmkX bVSjdX-69xVDJ48ZzaJSE_90Jf9vWrLueAoaAuBREALw_wcB&variant=8318139531325

What method are you contemplating to obtain your cam reference signal?

[spuggy]

I'm all for knock control. You don't need knock control - until you're glad you had it. Like insurance.

If it protects against fouled plug, bad injector/tank of gas, operator confusion or EFI misconfiguration, could pay for itself pretty quickly.