Plan for (inexpensive) 300+ hp SC motor

[Packy]

I posted this in the turbo and supercharging forum here but just in case you all didn't see it, here it is again....

This is my plan for an inexpensive 300-350 hp/tq motor. Please leave the "buy a 3.6 at home" and we all know the differences in turbo charging and supercharging and have heard that conversation. This is a multiple stage project that will allow me to fund it in little chunks instead of dropping 5 to 10 grand all at once. The first stage will allow for a lot of power without opening up the case or removing the motor from the car. I will do intake with EFI first then ignition then exhaust then supercharger with intercooling. Doing it this way will allow me to trouble shoot easier. Next stage will be beefing up the guts of the case. after I do this I should be able to get 500 to 800 hp. Have fun. This should spark some good conversation.

Engine:
90k miles on an early 3.0L 911 SC motor with larger ports and lower 8.5:1 stock compression ratio with a 915 tranny. – boy am I glad I bought the early 911SC instead of a later SC with the smaller ports and higher compression ratio.

Upgrade Plan (stage 1):
Eaton m62 supercharger – $100, bought from a friend.
This supercharger only takes about 25hp to turn it to full boost and it is a roots type blower. The snout goes bad on these but there is no catastrophic failure. When the snout goes bad, I will hear it and send it in for a rebuild. Use a breather tube from crank case to supercharger. The major issue is finding manifolds.
I have info from TurboKraft, Supercharging of Knoxville and TPC.
Water to air intercooler – $400
Extra weight but small and more compact in engine bay. Also has higher efficiency due to the heat capacitance of H20 compared to air. Radiator up front of bumper. Use a 5 gal fuel cell with breather and cobra pump. -
Oil Cooler upgrade – $400, estimated high.
Don’t like all the expensive Porsche options, will fabricate my own. Oil coolers are cheap with a fan and should work just fine. Located in wheel well, maybe double in both wheel wells.
Twin plug direct fire ignition - $200 + $450 for machining
Ford EDIS system works great with twin plug, 6 pack, VR crank sensor 36-1, timing controlled with computer with serpentine crank, fan and S/C pulley. I was thinking of going with the XDi2 set up from Clewett but this way is cheaper and should work just as well. Also, making the XDi talk with my computer would require just a little more effort so EDIS is a little easier. Twin plug machining ($450).
Carrera Intake with throttle body - $600.00
No porting head necessary because I have the larger ports already. Many sources and bids. Add TPS – ’86-94 throttle body has this.
Computer – $500.00
I would have went with tbitz racing full set up but he doesn’t have the computer I need to work with a supercharger, so I will use everything he has but the computer. Our fuel pump is rated at about 70psi and 54 gph from what I remember so fuel is not an issue. I will be using 45# injector which are good for up to 400 hp. I need the MS2 chip to control boost and tbitz uses the older chip. I will also be using the wide band hot 02 sensor to make tuning and cold starts better. Boost control and ignition controlled by comp. I will also set my rev limiter at 6000 or 6250 because the rods are not forged and the rod bolts stretch at about 6700 rmp.
1-3/4” Exhaust – 2k
Ceramic coated headers that stop after the collector. I should be able to get this for about 500-700 dollars. I want them to stop at the collector so I can throw on cats if I need to. Custom muffler with a GT3 style double tips coming out the center of the bumper ($900).
Custom bracketry and Supports - $TBD
Will be mimicking the setup of the 993/964 kit from TPC. Need to make tensioner plate, buy tensioner, coil bracket, fan bracket, left bracket, right bracket, inlet manifold, discharge manifold, discharge elbow and bypass air duct.
Pistons – 0.00
8.5/1 compression ratio is fine. Rings may have blow by but a breather tube from the case to the SC will lower the positive case pressure.
Rods – 0.00
Stock rods will work fine for now.
Hardware – 0.00
Limiting factor for strength of motor. Check head studs for bad dalivar studs and keep boost low for now (.7 bar). RPMs need to stay below 6700 for rod bolts. Engine cooling is important too.


Upgrade Plan (stage 2)
Larger pistons/cylinders, probably 3.2 to 3.4 – $4300
ceramic coated JE pistons, hastings piston rings orniresist LeMans rings ($450 plus head machining work).
Crank – $750
Mag crank, cross-drill, R&I oil plugs, micropolish, balance
Hardware –
head studs and other fasteners ($675), rod bolts ($285), rocker locks ($360/set) + motorsport seals ($96), turbo exhaust valves ($450/set), valve springs ($550) or ($750) with Ti retainers, motorsport timing chans and guides ($350)
Case mods –
3.0L case, boat tail ($300) dowel pinning case halves ($500), upgrade oil squirters ($300), 3.6L oil pump ($900) maybe a 993 super sport camshaft, high performance valve springs, gaskets ($95),
Heads -
O-ring the cylinder heads.
G50 Tranny – 5-15k
87-89 tranny with a 240mm clutch with hydraulic actuation, newer syncros, lightweight flywheel and limited slip differential.


References:
Hargett engineering, TurboKraft, Supercharging of Knoxville, TPC, Wayne Dempsey’s books, and a whole lot more that I’m not putting up here.

I am done with my planning stage and am now collecting components. I can't wait to take this puppy to the track looking relatively stock (except for bumpers) and killing those C5/C6 corvettes and beemers. HA!

-Patrick
____________

[lindy 911]

I have a naturally aspirated 3.0 SC I call grenade. What do you call yours?

Lindy

[Packy]

I call mine Balls.

[lindy 911]

Sounds appropriate, I wish you luck.

Lindy

[Oh Haha]

I've liked the idea of supercharging versus a turbo because of the uniqueness. I don't know if the parts you plan to put will work but I intend to follow your trek in this area.

Do you plan to make any suspension mods or is the car already done in that respect?

[Packy]

I plan on upgrading the braking before suspension. If or when, I do suspension it will be with stiffer torsion bars. In the mean time I will be stiffening the chassis with strut braces (front and rear) and the Brey-Kraus harness truss and roll bar set up. Though this isn't really as strong as a real roll bar I'm guessing. Besides that I think my suspension is fine. I don't really need coil overs I don't think. The brakes definitely need cooling right now. I boiled my brakes last time at the track. Not too much fun.

[snbush67]

Stage I - looks resourceful but still ~ 4500

Stage II - does not look inexpensive ~ 11,000

G-50 for 5-15K, you should call this stage III

Thats projected parts and machining costs @ ~ 20-25

[SandyI]

The stock sleeper look will be great on the street and surprise a lot of folks in a straight line.

But for the race track? I didn't see the following items in your budget --
1.) Full race cage
2.) Six point harness (for passenger too?)
3.) Hans friendly race seat (for passenger too?)
4.) Detachable steering wheel
5.) Custom bodywork -- fenders, front valence, biplane rear wing
7.) Track wheels
8.) Track Tires
9.) Additional gauges or compact race dash?
10.) Fuel Safe gas tank

And I only bring this up because a 911 with 500+ HP on a race track is dangerous as hell no matter what your skill level.

Be safe. Have fun!

[LWJ]

Since it is your project and I can dream about it, how about replacing the intercooler with methanol injection? Probably much lighter. Probably simpler once you get the parameters dialed with the MS. Probably a lot better at cooling the charge than an intercooler.

Just a thought.
Larry

[rnln]

please keep us posted.

[Porsche Head]

I was going to go the Eaton M90 route but decided on a Rotrex for better efficiency however you are going to get more low end boost/power. I have the C38-71 good for 350-500HP.

Good luck I'll be watchin your progress, I am still working on some fornt end and brake upgrades to get it back on the road first.

[Packy]

Stage 1 is where I get the cheap power. 4500 isn't bad for that much hp and tq on a PORSCHE!!! oh yeah!!!! I also figure I'll be buying the G50 tranny and clutch when my 915 goes out. that probably will be stage 3. I also may do head studs a little early, depending on how out of control my spending habits get.

As for the race gear, I'll have harnesses for both the driver and passenger but no HANS device yet. I'll be fine with out it. The cage, I have a plan for a half-@ssed roll bar. Check this out. I also have fuch 7s and 8s on the car now. When the tires get low I'll throw some DOT slicks on.

As for the methanol, I thought about that for the cheap route. My roommate, the corvette guy with a 500 hp and 2000lb LS1-RX7, tried to convince me to go this way but I'm looking for a street/track car. The methanol obviously runs out so I'm going with an intercooler.

Porsche Head- I'm going to check out that supercharger. Do you have any pictures of your set up? What kind of computer are you using? I will be looking for somebody with a MS2 that has a supercharger so I can steal their maps. I'm going to love the torque on this car.

[Packy]

of course add 10-20% for the unforeseen.

[Kroggers]

I know nothing about superchargers, so look forward to following this project in the hope that I get some better understanding and education...

[Packy]

Originally Posted by Kroggers

I know nothing about superchargers, so look forward to following this project in the hope that I get some better understanding and education...

Superchargers are easier than turbos, that's for sure. But same basic concept of forced induction. Except with a supercharger you don't get the losses from back pressure but you do with a crank driven compressor. With a m62 S/C at 10psi (2:1 overdrive at 1200 rpm) it only takes up 25 hp. At 5psi it only takes up about 15hp.

How Supercharger & Turbocharger work

In the words of the great Ricky Bobby from Talladega Nights - "I wanna go Fast!"

The best part about this project is I can stage the builds.

[jtkkz]

My cousin did that to his '72 911T wth a 3.0 SC engine, supercharged it...

[Porsche Head]

Packy,

Rotex? Here are a few links...also attachments. I have the C38-71 on the bench, doing calculations and planning at this time, like I said the interior is just finished and now wrapping up the front end (tb/big brakes/rebuilt steering/turbo tie rods...). Dude you live in Santa Cruz, you are right around the corner.......well sort of

My Target is 350-420hp, will add water injection and some MSA6AL boost retard to get there but I am sure 320hp without any major tweaking, take a 2200lb car and 7:31 gears......my car is already quick with the 79 3.0 and the gears+SSI+exhaust.

Rotrex A/S
Rotrex A/S
K-Series Programmable ECU for the D17 Civic
So I drove a Rotrex on Sunday at Buttonwillow... - Miata Turbo Forum - Home of the turbo Mazda Miata.
Koenigsegg CCX


yes you will love the torque....I have seen a few posts and some vendor input (knoxville supercharging) basically instant tq so be carefull with the 915!!! I hear anywhere from 300-350hp can be expected but you want to watch out for knocking with the heated intake charge vs. the Rotrex. I think that will be the limiting factor with the Eaton, cheaper to start but cannot put it too much things will blow appart if you don't have advanced electronics+intercooler+water/meth.

Rotrex will be super cool compared, at least 100 deg at mid boost levels and only takes a few HP to run. This means no need for all the extra expensive hig tech stuff on a low tech motor. Some Honda/Miata guys are running 15psi on stock motors they would never try that with a roots or screw however the screw (new Eaton + Whipple) is certainly better. My thought is if you are going to keep the cost low and the build much more simple but still be able to run higher boost (up to 15) then Rotrex is better.

Better low end TQ can be had by running the charger faster (pulley change) and bleeding off excessive (say 12psi) to keep the top end from building too much boost. The result is similar to the roots but will not run out of steam like a roots un the top end. I have seen 9k rpm motors running a Rotrex and they are still building boost.

[flat6pilot]

Whatever became of this project?

[Laneco]

I always love building cars on a budget - as that's the only way I get to do them - LOL! But regarding 300 hp for cheap out of a 3.0 let me offer this advice...

Cheap, fast, reliable - pick any two.

angela

[Packy]

I moved to southern California and had to put the project on hold. I'm actually going to pull the car out of storage in the next week or two and get it going again.

I live in Newport Beach now, which is pretty much the worst place ever to build a project car.

-P