Hello all,
Long time lurker here...thought I would introduce my project of the past 12 years and ask for some advice based on where I would like to go in the next steps of the adventure.
I purchased this car back in 2010 as a running and driving project with the hope of using it as a platform to learn on and keep long term. It has been everything I hoped for and more. The car is a 1975 U.S. spec 911 Carrera Targa, number 112 of 174 built that year. It is a numbers matching car minus the transaxle which was replaced at some point in its life. It was also painted Guards Red, as it was originally Grand Prix White with gold stripes. I have touched about every nut and bolt on it, from rebuilding the suspension, to dropping the engine and transaxle to replace the clutch. I am a huge fan of the 934, and have taken some of my favorite aspects of that car and combined them with the '75 Carrera. Some specs are listed below:
Suspension:
- Elephant Racing rubber bushings (sport hardness)
- 21mm & 30mm Sway Away solid torsion bars
- Stock 20mm and 18mm sway bars
- Koni 1039 Sport and 1214 Sport Shocks
Engine:
- Stock 2.7L S-spec with Bosch CIS
- Carrera chain tensioners
- 1x Bosch 044 fuel pump, raised system pressure to 95psi, running a mix of 93
and 110 octane
- GReddy Type-S BOV vented to atmosphere
- 934 headers with dual 930 wastegates and custom 0.4 bar springs
- Twin scroll T3 housing KKK OM422A turbo for testing purposes
- 123Ignition distributor with factory 2.7 S advance curve, vacuum advance,
and addition boost retard setup
- Retrofit CDI+ ignition box, using default settings.
- Clewett Engineering ignition wires
- Elephant Racing Widemouth oil cooler
Transaxle:
- 1976 mag case 915/44 with 7/31 R&P and open diff.
Wheels & Tires:
- 15x7 and 15x8 Fuchs with 205/60-15 and 225/60-15 tires.
I have been extremely happy with the current setup, however the engine has excessive blowby, smokes heavily under load, and is in need of a rebuilt. The case to my knowledge has never been split. Cold compression test results are as follows:
#1 142 psi
#2 60 psi
#3 162 psi
#4 152 psi
#5 140 psi
#6 82 psi
I knew this day would come eventually, as it has been turbocharged for the past 10 years, so I am trying not to be too disappointed... I am assuming it is the rings or pulled head studs. I have not done a wet compression or leak down test yet.
...So in light of that, I would like to start making plans to rebuild it, and put together a list of things that should be done to meet my goals. I would really like to keep the mag case and 2.7L of displacement, spin it up to 7K rpm, and make 275-300hp at the crank. I currently have a set of brand new (from the 80s) Arias flat top pistons for it. I am debating whether to source another 7R case and put the original one to the side with the other original parts, or use the numbers matching case. I know I will need to at least have the case line bored and have case savers installed; what additional work needs to be done to it to allow it to take 7K rpm reliably, and what other bottom end components should be upgraded over stock? I plan to run 934 cams specifically because I love the way they sound, and plan to use a 928 CIS fuel head using the extra 2 injectors for boost enrichment. Will the stock 2.7L S heads flow enough air to make that kind of power at a moderate boost level? Should I look into porting? Will the 3 bearing cam towers be ok with that aggressive cam profile? What should I use for valve springs? I still have much to learn but I am excited to start the next chapter of this project. I appreciate any advice you all might give, and if I am crazy for wanting to go this route you can tell me.
Thank you all. Pelican Parts and this community have been a tremendous help.
