3.0 SC High Performance Rebuid

[Kemo]

subscribed.

[lindy 911]

Update:

Waiting on parts to be finished at varoius machine shops around the country. I did get my pistons and bearing back from Poly-Dyne. Cases are ready with new bearings installed.

Lindy

[lindy 911]

December 1, 2009 update:
Bearings installed in case and Poly-Dyne looks great. New JE pistons with Poly-Dyne slide coat on skirt and thermal barrier coat on crown.
Took some time to pull all the unused crap out of the car; there's a lot of stuff that doesn't need to be there. I stripped out the AC and all related components and wiring. Stripped out all unused wiring and there was a ton up front. I will retain the heat and plumbing. Thinking about relocating the battery to the old AC well?????

Installed new rebuild pedal cluster. I need the return spring for the brake pedal if anyone knows where to get one.

Ahhhh; new (to me) 46mm Webers in great shape! Sourced from a Pelicanite!

Spoke to Arron today at Rennwerks; rods are scrap. Someone tried to balalnce by removing the web on the cap like a SBC. We're looking for some used Pauters or the like. Heads are good to go except for the usual exhaust guides and a couple of exhaust valves. We're just going to replace all the guides and exhaust valves. New 90lb springs and titanium keepers for the GE 60 cams and 7,500 rpm rev limit.

Barrels are in great shape with just a hone needed for the new 10.5 JE's.

Crank measured as new. Had it polished and it looks like it just came out of the box. I'm going to spend some time cleaning it with gun brush through oil galleys and pump lots of barsol through it.

Assembly should start in a week or so.

Time for a glass of red.

Lindy

[Carrerax]

Any updates on this? Just curious, how many miles were on the motor?

[lindy 911]

Carrerax,

Aaron will be shipping parts this afternoon so I can get started on the reassembly some time in the next few days. The car has 97,000 miles. I'll post pics of Aarons work when I get the pieces in.

Lindy

[Dees 911]

I hope that bottle of Coors Light(in the pic of the piston) is for holding cleaning fluid or oil or something. You don't actually drink that stuff, do you? BTW, interesting build and pics. Thanks.

[Eagledriver]

I think the problem with Marks motor is he put 8000 RPM cams into a motor he redlines at 7300. GE 40 or 60 would've worked much better.

-Andy

[lindy 911]

Dees 911,

In Texas we use Coors Light in place of water, just about the same thing. If you will notice, the mountains are blue on the label signaling the "water" is cold! I just got off the phone with Aaron and all parts are in the FedEx bin waiting for pick up. I am getting very excited. The more I research the more I believe this motor will make 100 HP per liter + or - a few. My goal for weight is 2300 pounds; with 300 HP this SC should fly.

Lindy

[lvporschepilot]

With my experience with Ferrari engines, using that kind of cam in a 3L 308 engine spinning that high leads to disaster on the street, especially with carbs. A 308 engine with that kind of compression and somewhat similar cams makes about 285bhp @ about 8k rpm. I would not think a 3L 911 engine would not be far off that. I believe 275rwbhp would need about 325bhp with a 915 tranny.

[Eagledriver]

Lucky he's not building a Ferrari engine then! GE-60's are perfect as is the 7500 RPM for your application. I suspect the power will be around 275 at the flywheel.

-Andy

[jmz]

another datapoint.

3.0 Elgin Mod S cams, 9.3:1 C.R. Mahle pistons, Heads rebuilt and ported by Competition Eng to I think 39 on the intake...been a while. Weber 40s w/ 36mm venturi, tall manifold, single plug ignition w/ MSD 6AL and SSI exhaust and I too had Poly-Dyn coat the pistons.

Dyno 212 rwhp at Protechnik a number of years back.

[lvporschepilot]

GE-60 is 264 dur @ .050 last I checked with the ex being around 253 @ .050? This is pretty hot street stuff. Lower end bhp (below 3500) might be about even with stock, but it's of course the top end which gets all the power. I am sure the engine will run well from idle on up, but do not expect a big power gain at lower rpm where much of the street driving is done. 230rwbhp might be a more realistic goal. Sounds like a ton of fun regardless.

[lindy 911]

I know the HP figures are all over the board but I'm optimistic that we will be in the 285-300 range at the crank. I am familiar with Pro Techniks chassis dyno and may ask them to make a pull or two when fine tuning as they are just down the road from me in Houston. I also have access to a water brake dyno that we use for motorcycle engines that will handle 500 hp. It will require a custom set up to use without the trans axle to measure crank hp. We'll see if that works out.

JMZ, I'm looking at making most of my HP at above 5,000 and will probably peak near 7800 or so. I had Arron use racing springs and titanium retainers for this reason. We also used Raceware rod bolts with re-sized stock rods. With the big port '78 SC heads and PMO manifolds with 46 mm Webers, I think 285-300 is very do-able and will live. Making 100 HP with 1000 cc is not hard with an inline four; I don't see why a flat six should make any difference.

The main focus of this build is to create a sport bike that has four wheels. No AC, no extra crap and as light as I can reasonably get it without breaking the bank. It will not be a daily commuter car and will be treated much like a Ducati or RC51. My wife says I'm too old and stupid for two wheels now (especially around Houston) but she is cool with the black Targa.

Lindy

[lvporschepilot]

What is the intake flow at 28" (or 10" which you have)? A more reaslistic bhp figure might be deduced with that extra figure. From what I can tell now with this cam, dynamic ratio you are running, installed centers of that cam and lsa, peak bhp will probably not be much past 7400.

Definitely get it on a flywheel dyno for breaking in, and then I would try and find a Mustang dyno. Dynajets are for bragging rights while Mustangs give more realistic figures. Must be why they are known as heartbreaker dynos.

[jmz]

Lindy,

I'd say you are pretty close as long as everything works in concert together.

Assuming a 15% drive-line loss I'm at roughly 240-245 at the crank. I am not sure how the Mod S compares to the GE60 cam - at one point I thought they were the same but have been told that mine is more like a GE40...

So if you have bigger carbs, bigger cam and more compression yours should be pushing a few more ponies than mine. ...mine is probably pushing about 150 now though... major tuning issues or something worse. It's been parked for about a year now while I devote my time and energy elsewhere. -hope to get on it pretty soon though.

Don't forget about your gearbox. I am not sure what you have but you can make these cars a lot more fun by tightening up the ratios a bit.

[lindy 911]

Jay,
I've given the gear box thing some thought, but not much. I've never been in a 915 but it looks pretty straight forward. I hate to keep talking about motor cycles here but a close ratio box does make a huge difference in the two wheeled world.

As far as "intake flow" is concerned, I have not one clue. If peak HP happens at or near 7400 that's perfect; but I suspect it will be a tad higher. I have no equations to prove this up other than "seat-of-the-pants" experience. Our 1000 cc Kawasaki motors make 120+ hp naturally aspirated at about 11,000 rpm. The reciprocating mass is much smaller, as is the size of the valve train so they can stand the revs. The cranks also have roller bearing mains in a wet sump and can be spun to 15,000 without issues so these are not "one-pull-wonders". The same motors with reduced static compression and turbo charging make well over 300 hp. They are blinding fast; 70 mph roll on front wheel float!

Anyway, I love this site and the conversation. Keep it coming!

Lindy

[lvporschepilot]

Turbo stuff is fast, no doubt about it! Call me old school, but I prefer naturally aspirated engines. Both push different buttons I guess.

Intake flow is the big one when it comes to any engine, but especially naturally aspirated. If you don't have the proper cfm from the heads and intake manifold, than a great cam is not going to as great as it can be. Your carb setup beefed up your cfm in a big way, but several heads just don't flow well over a certain amount of lift. I am not a Porsche head expert, but I am well aware of engines that run out of any substantial flow gains at say .300 lift making any further lift a moot point without substantial head work. I know the SC heads from '78-'79 engines had somewhat larger ports than the later SC, but neither flowed as well as 3.2 heads from the factory. Should be ok regardless, but that is where the 100bhp per liter kind of power is hidden.

[lindy 911]

From what I understand and have gleaned from this site, the '78-'79 SC head being hemispherical and with the valve angle utilized is an excellent hot rod head. When asked, the experts here have not mentioned retro-fitting 3.2 heads in place of the early SC head for a performance gain. I'm not saying it isn't so, just that no one here has mentioned it before. I do know that the SC heads work very well and like a lot of cam.

Lindy

[lvporschepilot]

Sounds like a good thread for me to research!

[lindy 911]

I received my parts from Arron over the weekend an they look great. Nice work Arron! Just an FYI for those of you building a motor in 30-40 degree temps., the assembly lube recomended in Waynes book is VERY thick in these temperatures. I assembled my case and it looked beautiful.... until I tried to rotate the crank. It would turn but it took a lot to get it to move by hand using the front pulley. I thought surely something was amiss so apart it came. I cleaned the the crank and bearings of the assembly lube and then lightly oiled with Mobil One and put it back together just to see. It turns easily and freely now with a slight drag. Wow, now I have to reorder through-bolt "O" rings and wait for them to get here.....drag. So either heat your garage or roll the dice. I'll post some photos later.

Lindy