my 3.6 turbo build

[matty74]

Hi Guys,

I'm getting close to my engine build so this is what I have and what I'm planning on doing...

any advice apprciated



Twin plug 993 3.6 litre
Motec M4 efi
993 cams
CR 8:1 and 1.0 bar boost
Single GT35R turbo charger
B&B headers
Alloy Manifold has been honed out for better airflow

[Reaper930]

hell with that CR & discplacement you can run 1.3 all day long with no issues...sounds like you got a decent start.

[matty74]

1.3 sweet what kinda hp at a guess you reckon?

[pkracer21j]

Get with Reaper on cam selection too! he has some special spec'd cams... with EFI you can do much better then 993 cams.

[spence88mph]

1.0bar on a 8:2CR Carrera 3.2 gives 520+ CHP, 1.3 on a 3.6 would have to put you in the 600+ maybe even 700 region, nice region to be in!

[matty74]

is it better to go 8.5:1 and go 1 bar or lower CR higher boost?

How about GT2 cams rather than 993? what difference does it make?

[Reaper930]

8.5 is going to give you more power off boost, but with a 3.6 you don't need it. I'm running 8.5's in my 3.8 and frankly it was a bit much off boost on the torque side of things when boost hit.

The secret to the 3.6 & 3.8 big discplacements is delivery of power and selection of gear box. So many people build these on paper without real-world experience and wind up with a torque motor and short gears, spinning tires all day long and no transfer of power to the pavement.

Not to mention with lower CR you can dial the power up and down a bit more as its dependant on the turbo. But read this next sentance carefully. The 1 bar boost limit regarded by the whole community is a bit of a myth! Sure the motor will last just about forever at 1 bar, and its reliable power - but if you build the motor right, flame ringed heads, motorsport valve springs, Ti retainers, high grade valves and port match everything - there isn't any reason you can't run more boost.

Where people get into trouble is heat, and while a big discplacement motor will generate alot more heat than a 3.3 or 3.4, this is where you pay special attention to intercooler placement & ducting, & oil cooling capacity.

A motor can boost happily at 1.6 bar all day long - but its the heat and pressure that determine if the motor is happy, or dying. Monitor cylinder head temps, IAT's and EGT's, if you keep those in check, the motor will last along time.

Just like paint work - its all in the prep of the motor, the parts used, how everything comes together and works in unison.

For cams - if you want a big style almost 935 cam without being too peaky like a Gruppe B cam, call webcam and ask for a GT2 Evo cam with a 106 lobe center. That's what I have and trust me, you make some f*cking power.

A 3.6 with 8:1 CR at 1.3 bar will be good for about 740bhp at max boost - but will give you an easier to drive street car (assuming you're not going to have monster 345's out back) that won't spin the tires everytime you take off from the stop light. Going with 8.5:1 will give you a bit more torque down low, but unless its slow track configurations and you need the extra grunt, i'd go lower CR with adjustable boost.

[Reaper930]

And as a side note, for the love of God - put the chassis on a diet. Street car or track car makes no difference. You feel the removal of weight from the dig, the lighter the car the faster it is off boost and less stress on the motor.

I know its been talked to death and people don't want to live with things like race seats, no sound deadening, no heat or A/C, fiberglass panels and lexan windows but I must tell you - a car around 2,000 to 2,200 lbs at 500hp is blindingly fast, so just imagine what you could do with that same weight range and 650-700 hp...

It is the secret that made these things the legends they are...

[RarlyL8]

Off the shelf B&B headers? On an expensive high HP build? I have some design ideas if interested.

[Reaper930]

^ I would take his advice on the headers.

[matty74]

Reaper930 - thanks for the info, I have already striped out sound deadening and using glass where possible, it is a 73 RSR shape so I have to figure out how to get the intercooler in the car as I'd like to squeeze it all under a duck tail, I have seen a few other guys do it.

I have a 81 930 box I am planning on shortening (74 wide body) with a Kennedy engineering clutch, taller 1st shorter 4th

Brian - I'd love your equal length headers but I'm, restricted for budget right now so I will talk to you at a later date, the B&B's will have to do for now.

Apart from the Ti retainers and firering the heads is is worth putting corrillo rods? the car will be s street/track day car but longevity is just as important as HP.

[Reaper930]

corrillos would be nice but not a must, it all depends on the RPMs u plan to push the power at. I run them in mine, but its not a "must". But flame ringing the heads, that needs to be done...no doubt.

On the IC under the ducktail, one thing you have to look at is airflow, not just "do you have an intercooler yes or no". If you don't get airflow through the core you're just adding a heat sink for the charged air. The only way to do this with a duck tail is to do it how LARennsport did it, with a custom tail to fit a 993 twin turbo IC under that seals to the IC and has flow through.

What front bumper are you running?

[matty74]

I'm running a glass getty front bumper 73 RSR style, I will be mounting a front setrab oil coooler the bumper has a nice big opening at the front for air flow.

I figured I'd have to modify the tail to get the air flowing through it

[RarlyL8]

This is what I recommend for your build. 1.625" primaries, merge collectors, precise waste gate control for each bank and a split plenum T4 flange for your big Garrett. You're leaving at least 50HP on the table using anything less.
Give me a head's up when you're ready and I'll put a set together for you.

[matty74]

yep now worries Brian, they are exactly what I want long term

[spence88mph]

they look awesome Brian...

My next mod, you ever get heat working?

[RarlyL8]

Heat exchangers have been revised and the test set being built. I'll test them before producing a full run. The originals were not cut correctly and did not seal as well as they should. Warm but not hot. It's cold now and I need heat too!

[gsmith660]

That is pure sex!!!

Originally Posted by RarlyL8

This is what I recommend for your build. 1.625" primaries, merge collectors, precise waste gate control for each bank and a split plenum T4 flange for your big Garrett. You're leaving at least 50HP on the table using anything less.
Give me a head's up when you're ready and I'll put a set together for you.

[Reaper930]

Originally Posted by matty74

yep now worries Brian, they are exactly what I want long term

Keep in mind when you tune your EMS with the GHLs, you'll need to tweak the tune with a different set of headers.

This might sound like i'm plugging Brian's stuff but here's the deal - if you give yourself a bit more time to get the $ for the project to do it right the first time and sell the GHLs to someone else - you'll only have to tune once. And trust me, i'm tuning right now and can say when its over I don't ever want to have to go back and do major tuning again!!!!!

Just my $.02 from someone who is there right now.