Input on engine build

[storegnu]

Hi, guys!

My trusty old 930 now really needs an engine overhaul. It’s a -80 Euro car, mostly original. It will be used for street, with about maybe two track days each year. Still it’s just a fun car for the weekends, so no need to think very practical.

I have decided to scrap the the CIS and go for a full EFI system, as I have done with my 911 SC Targa. When the engine is going fully apart, split case etc, I want to take the opportunity to get a fair amount of more hp.

My own thoughts for a build list are as follows:

- Full EFI, with e-gas, knock sensors, ignition etc. Thinking of using the Maxxecu Race, as my engine tuner uses this one.
- Larger fuel pumps.
- Larger oil pump?
- The car already has Fabspeed headers with heat. I guess these will be good enough?
- I have a brand new Turbokraft half bay intercooler sitting on the shelf. Would like to reuse this, if I not absolutely need to go to full bay. Chris has told me it will support 600++ hp.
- I have some doubts about the intake. Ideally I would like to use the original flat intake. Thinking of opening this as much as possible and then matching and flowing the heads. Will I lose a lot compared to for instance an intake from a Carrera 3.2?
- Stronger rods?
- New pistons and CR 8,5:1for better drive ability off boost.
- Thinking about 964 cams, but there could be lots of better choices. I do not mind developing the power a bit higher up the power band, as I am thinking that the increased compression helps a bit when off boost?
- Do I need to twin plug?
- Which turbo do I want?
- Wavetrack LSD. Currently have no LSD.

I will do a full suspension overhaul as well. Is it OK to refresh everything or would you use other parts?

Will be using only 98 RON (equivalent to 93 in the US) fuel. The car will be 90% street used and maybe a track day or two each year. Will want to keep AC and such comforts.

I know that many of you have a lot of experience with 930 engine builds and would very much appreciate input from you.

Here is the car:

[Axel84]

Call jan henry løken the old son workshop boss �� regards Axel Norway

[storegnu]

Thanks! 😁

[David]

What is your goal? HP? Drive ability?

EFI will get you almost everything you probably want with the right turbo and cams.

[storegnu]

Hi, David!

Thanks for your reply. I should have said something about that in my original post. I think that 500+ RWH would be a minimum goal. When it comes to drive ability, I would not want pure racing characteristics, but I would like an engine that pulls all the way to the top and don’t mind if that moves a little power off from low RPM.

I think that choosing cam and turbo is where I really need some input in this.

[TurboKraft]

3.4L
ported heads & intake manifold
964 camshafts
GTX35R turbocharger or equivalent
Longneck intercooler
reuse your exhaust
EFI with twin-plug ignition, e-throttle, Lambda, boost

That will support 500whp on your premium gasoline with a conservative tune -- we've done it many times on our awful 91-octane.
Off-the-line torque will be comparable to a 3.2 Carrera, quite responsive and driveable.

Switch to a full-width intercoooler and you'll get more airflow through the engine with better cooling. Two recent builds both did over 550whp.

[storegnu]

Chris,

Thank you so much for your answer. Regarding the turbo, I was planning to get a Garrett GT35R (2” in, 3” out, as I guess this is the closest to drop in). However, the current turbo in the car is a K27-7200, from the early -90s. I guess there is quite a difference upgrading to the latest Garrett?

[Axel84]

I have 964 camshafts for you here in Norway storegnu

[TurboKraft]

Originally Posted by storegnu

Chris,

Thank you so much for your answer. Regarding the turbo, I was planning to get a Garrett GT35R (2” in, 3” out, as I guess this is the closest to drop in). However, the current turbo in the car is a K27-7200, from the early -90s. I guess there is quite a difference upgrading to the latest Garrett?

Very much so.
The K27 has a much smaller compressor wheel and won't make the airflow you are looking for. Plus the turbine wheel is limited in its throughput.
It can be gutted and remanufactured with new internals, but by the time you ship it back and forth, it may not be cost effective vs. a new Garrett outright.

[David]

I had a hybrid K27HF2 turbo that seemed similar in output to my current GTX3582R but slightly later boost, a bit more expensive, and maybe not available anymore.

[David]

I'm goofing off at work and thought I'd summarize your build

Reuse:
Crank
Rods
Oil pump
Intake manifold ported to increase intake size (I'd go Carrera if you can find it)
Full bay intercooler if you have it
Ported heads with fresh valve job and new springs, machined for twin plug.

New:
98mm pistons and fully finned cylinders (8 or 8.5 CR?)
New turbo (GT35?)
964 cams
Fuel injection ECU (with sequential injection capability and ignition)
Crank trigger and sensor
Cam trigger and sensor
Intake temp sensor
Intake manifold air pressure sensor
Intake manifold spacers to handle fuel injectors
Big enough injectors to handle 500 whp
4 port waste gate valve (to handle more than twice spring rate if needed for boost)
Lambda sensor after turbo for tuning
12 coil on plug coils?

[storegnu]

David,

Thanks a lot for summarizing! I think I will go for the Garrett turbo.

I do have the Turbokraft half bay intercooler. If I had know that I would go full EFI one day, I would have bought a full bay… I would ideally like to have the AC-radiator in the wing, but I have a new one up front and an extra to put in the fender. (Both from Griffiths) If that gives enough cooling power, it’s even more tempting with a full bay.

[David]

More thoughts:

If you use stock rods, I'd change rod bolts.

Also change head studs

And of course Carrera chain tensioners if you haven't already done it.

[storegnu]

So stock rods are OK for these power levels? With new bolts, that is. I guess it´s revs that are the main problem for these rods. On the other hand, this build is going to cost, so new roads are not all that much more money…

[David]

I put Pauter rods in my engine just to be safe. Nice thing is they're lighter than stock (6 Pauter rods weigh about what 5 stock rods weigh).

I am curious to get Chris' take on enlarging piston squirters and flame ringing the cylinders at the heads. Two things I didn't do on my build.

[Tippy]

If you could get some Carrera 3.2 heads and intake, you'd be making quite a jump in HP alone with those. Paired with 964 or larger 9933SS cams, hold on!

'camgrinder' may be able to grind your stock cams to the 964 profile? Not sure, but worth asking him.

I'd think stock rods are fine at the RPM limits of said cams, but of course a lighter rotating assembly is easier on everything and would make a little more up top HP wise.

[David]

You can bore out the 930 heads to fit the Carrera intake like I did:

[storegnu]

Hi, Tippy!

About the Carrera 3.2 intake. Is there really that much difference when porting the stock intake max?

[storegnu]

Quick update here:

Engine is out of the car and in the process of being taken apart. I have had some mission creep and are now leaning towards more power higher up in the power band (cause it’s fun!).

I have decided on the following:

- Carrera intake.
- Carrillo rods.
- Turbokraft full bay intercooler.
- Full refresh of all seals, springs etc.
- Gearbox overhaul and add wavetrack.

Still not decided:

- 98mm or 100mm piston/cylinder set, 8,5CR. The 100mm seems a lot more expensive! Anyone has experience with them?
- Turbo. Leaning towards the GTX3582R GEN II. I see this new generation should support at lot of HP.
- Cams. Due to going with 8,5CR and wanting the engine to develop power into relatively high RPM-band, I am considering the GT2 Evo cams. From what I have read, they should be OK off boost with the 8,5CR and move the power band up higher. Another stock alternative is maybe the 993SS?
- Exhaust. I have Fabspeed, but I guess I have to either rebuild what I have or go for a full new custom system.

Anyone have experience with this combination? The goal is to have a car that has at least OK drive ability off boost, achieves boost as early as possible and still deliver power at 7000+ rpm.

[TurboKraft]

Originally Posted by David

I put Pauter rods in my engine just to be safe. Nice thing is they're lighter than stock (6 Pauter rods weigh about what 5 stock rods weigh).

I am curious to get Chris' take on enlarging piston squirters and flame ringing the cylinders at the heads. Two things I didn't do on my build.

Bigger squirters are a great idea with a bigger oil pump.

Flame rings: we do them any time someone wants 500whp.
Like good head studs, rods/bolts, and valve springs -- it's insurance.