Question regarding 3.0L performance
 

I put a 1980 3.0L with 1979 heads, Webcams, SSI's with pre-74 exhaust in my 1975 911s. It has pop-off valve, I'm putting in a twin-turbo 993 oil cooler in the front. Supposedly this engine will put out about 200-210 max as far as horse power. What else can be done to increase the HP on the 3.0L but still keep it reliable?

Thanks,
--Michael

I probably not a whole lot of help here, I have a wopping 180hp of pure fun out of my 3.0. Oh well, I still love it.
How you doing Michael? Back home?

Still running CIS? I hope you put the right camshaft in there?

-Wayne

Wayne, still running the stock CIS, as far as the cams it has the 20/21 I believe ( it was fully rebuilt by Eurosport, 1980 case, '79 heads, webcams, new Mahle 9.8:1 P/C, SSI, Carrera tensioners) I bought it of one of the board members. Runs strong, I'm just wondering if I can get more power, I mean first I should probably learn how to fully drive it since it's my 1st 911!! :) I thought it was possible to get a lot more HPs out of these engine. Any thoughts? I will probably go to a 3.6L eventually when I have the cash. In the meantime the car has been on a serious diet, it has the C2 fiberglass rockers and F/R bumpers, no A/C, RS doorpanel, no power anything except for sunroof, Corbeau seats, etc...so I'm pretty sure I'm 250-300lbs lighter than a stock one. Does anyone know how much a '75 weighs stock?

Ryan,

Thanks for asking, yes back from the hospital, but the pain just doesn't go away and I'm still bleeding a little from my bladder which is no fun! :( Are you local here by the way? I live in Agoura.

--MIchael

I live out in Highland, by San Bernardino and Redlands. Are you feeling up to going on the mountain drive with us Sunday?

Sunday Mountain Drive

Glad to hear you're home, take care of yourself.

Man - you are hard core, my 73' with and SC motor (stock with SSI) is scary fast. You are an animal. I would like to see how you do the TT oil cooler up grade, post pics when you are done.

Go to TWM throttle body fuel injection and crank fired ignition, not really that much HP but webber like throttle response with out the tuning. Then you can go to crazy cams.

Have fun

Ryan,

I would love to go, but my car still doesn't have the oil cooler installed and I sure don't want to fry the new 3.0L I bought!! :eek:
Believe it or not, I have barely driven this car since I bought it in April. As soon as I got it it went in the body shop for the new paint, then I ran across the motor on Pelican and bought that, so it was in the shop right after getting painted, now that I have had it back for a month, I've been re-doing the whole interior (new seats, carpet, dash, panels, etc..), had to get new tires, and realized that the car is not driveable in the Valley when it's 110 degrees with no oil cooler!! Spent the last 3 weeks looking for the oil lines for (my car didn't have anything), just found them last week cleaned most of it, now I gotta take the car to my mechanic next week so he can install the 993 TT cooler, but he's been busy building a real GT-3 for a customer..so as you can see it's frustrating to look at my baby and I can't even drive it!! :)
Hope we can do another drive soon (maybe the Pelican drive?) so I can meet all of you and you can teach me a few things..where should I go to take driving lessons so I can really handle the 911?

--Michael

HAHA..trust me I'm anything but hardcore! It's my 1st 911 and it will take me probably years before I have the guts to really push it. The car is fun as is, but I'm the kind of people who really likes to be "pushed" in the seat when you step on it, and it just won't happen with a 180-200hp engine. I'm not a "top speed" kind of guy, but would love to have a Porsche that does 0-60 under 4.0 sec someday!

--Michael

We'll definitely do it next time. I'm looking forward to seeing that car of yours. I would love to do new paint but I'm going to do a rebuild next year (I hope) , one thing at a time.
Haven't taken any driving lessons yet, owned the car for five years. I have learned a few things out on the road, lessons of experience I guess.

The engine you described is probably just about as efficient (powerful) as 183 cubic inches can be without super- or turbo charging. I'd agree that for nearly all of us, the best source of performance increases is seat time at a track, preferably with an instructor.

The other thing you can do is lighten the car.

Superman,

You guys know what my car weighs stock? It's a 1975 911S. I thought it was like 2600-2700lbs right?

--Michael

The engine you described is probably just about as efficient (powerful) as 183 cubic inches can be without super- or turbo charging.

I will disagree with that statement

A rule of thumb amongst tuners is 100 hp/Ltr for normally aspirated engines

In May I spent 2 days helping a friend set up the fuel management and dyno tune his 3.4L engine. When we achieved our best dyno pulls we had 311 RWHP, factoring in 15% for losses, wheel slip on the dyno etc, that works out to 367 HP at the flywheel.

I have a 2.2 Ltr car my car dynoed at 150 RWHP which is ~172 hp.

following these trends a 3.0 should would be capable of at least 300 hp

Anything close to 300hp would be awesome! Hell they get 260hp out of a 2.7 RS Spec right? What can't we get the same out of a 3.0L?

--Michael

read my post, you CAN get 300hp, it all depend on your checking account

Well, the rule I have been most familiar with (perhaps from a low-tech era) is one hp per cubic inch. That's good. Two hp per CU is tops. Or was.

I would still argue that with a few mods you can take the 3-liter Porsche engines to 1.5 (274 hp), but that taking them much higher than that, without pushing air in them, is difficult at best. An engine is an air pump. When it pumps a given volume of air, it is only capable of so much HP. Higher compression squeezes out more horses, but three liters is three liters. How many cubes in the 996 normally aspirated engine versus how many horses. I think those engines are 4-valve units.

Also, smaller engines are more efficient. The 'rule of thumb' measures we have touched on are not linear. Larger displacement gets diminishing returns. Imagine, those DOHC 2-liter go carts Porsche once built!

Anyway, I am intriged by this discussion and hope to learn more about the maximum horses we could possibly get with a normally aspirated, SOHC 3-liter boxer engine. I'm not sure I believe they can make 350 horsies. If so, how?

3.0 mods
 

I know I've asked this before, but can't find the thread - I'll print this thread out, though that's no guarantee, either. Nonetheless, what sort of preventative work needs to be done when one puts 20/21 grind cams in their SC motor? Secondly, with 9.3:1 compression and backdated exhaust, what sort of horsepower can I expect? I know Noah's ran 9.5:1 and Euro versions have 9.8:1. I was thinking of installing just the cams and leaving the pistons stock. Is leaving the 9.3:1 pistons in the motor a feasible idea?

Thanks in advance for any and all responses

A certain pipe?
 

Hmmmmm...tell me more, Warmonger...how's it work?

No, you don't need any special parts to accomodate the 20/21 cams. Indeed, i doubt if more than about 10 hp is achieved, peak. But what those cams WILL do is make your power band twice as wide, or more. they make the car remarkably more 'driveable'. While you have the rocker shafts out, it's a good idea to use the special seals to prevent them from leaking after reinstallation.

I can agree that carbs improve throttle response. TR is an elusive thing, but when you have it, you notice it. A carbureted car would be more fun to drive than CIS. It has been my understanding that carbs cannot atomize fuel better than injectors can, so they cannot produce more ponies, but of course there are going to be exceptions.

My horsepower beliefs are more conservative than most, it seems. With the 9.3:1 pistons, 20/21 cams, backdated exhaust, advanced but not knocking timing (thanks, JW) and fresh valves and rings, I could claim 230 hp, but I don't think I'm there. I'd estimate closer to 210. I know that my engine can go past 300 hp with radical cams and more displacement (3.2L), but at its current displacement (3.0L), I think it's a bit difficult to get above 260. A normally aspirated 3L engine would just about need to burn nitro methane to make 400 hp. So, if you can't get happy with 230 drivable horsepower, then you need the 3.6L transplant. They can make 300 drivable horses.

Wow so much information! Thanks everyone for your input.
I just wanted to go back to the weight issue for a moment. I mentioned in my earlier post that I've tried to lighten the car as much as possible. The stock bumpers are gone (almost 100lbs), A/C is gone (about 120lbs I believe), door panels are R/S, Corbeau seats, no power anything except for sunroof. Anyone has the exact weight for the 1975 911s from the factory? I'm guessing I must be somewhere around 250-300lbs lighter. I don't think there's much else I can take out as far as weight, I don't even have a stereo in there yet!
Also you guys mentoned that my engine with the current setup should be around 230hp. That seems really high, I've been told that even with the 20/21, 79 heads, SSIs this engine won't make more than 210hp. Another person told me that to gain a few more hp I would have to get the euro intake and fuel system and distributor as well. Any truth to that?

--Michael

HP/Liter
 

A few data points I found interesting

1967 911R (typ 901/22) 210 HP/ (80 x 66) 1,995 cc = 105 hp/l
1970 911S-T (typ 911/70) 270 HP/(86.7 x 70.4) 2,492 cc = 108 hp/l
1972 911RSR (typ 911/73) 308 HP/(92 x 70.4) 2,808 cc = 110 hp/l
1975 3.0RSR (typ 911/75) 310 HP/(95 x 70.4) 2,994 cc = 104 hp/l
(same bore/stroke as SC motor)

and just for fun,

1976 935 (typ 930/72) 590 HP (92.8 x 70.4) 2,856 cc = 207 hp/l

It looks like the best the factory was ever able to do without turbocharging was 110 hp/liter. It's hard to speculate as to whether that was the absolute maximum the design could produce: even the racing engines were designed for longevity (in racing terms, which probably means 30-50 hours).

Is it possible to improve on these numbers through modern engineering and technology? With electronically controlled fuel injection and crank-triggered ignition, maybe. I doubt we could do much to improve on the factory's titanium rods and lightweight valvetrain, though.

You have taken this system about as far as it can go.
There are deminishing returns on mods after backdating the exhaust. I doubt if you are seeing 230hp - only my opinion.

To go further you need to lose the CIS and the CIS pistons and add FI or carbs. I would think max STREETABLE hp for a 3.0L SC engine to be ~250. Any more (usefull) power would come from boosting.

I think you'll find that while it's possible to get 1.5HP/cu in. it's going to require shifting the powerband higher in the rpm range and will hurt lowend torque. I once built a 500HP 302 Ford engine for dragstrip usage and while it was wicked fast it was also undrivable under 3000rpms. From what I have seen of 911 engines they are a much better starting point for high rpm HP with nice large unresticted ports, excellent balance, and light easily revved compontents. My 2.0E engine loved being driven above 3000 and throttle response through the non-original Zenith carbs was very sharp once I tuned them. Currently I'm halfway through installing a 3.0SC into my car with early exhaust and modified Zeniths and I'm expecting around 200-210 HP. While I'm sure you'll get to 275-300, you'll need to consider other things like gearing for example that allows you to stay in that higher powerband. Bigger cams will require higher static compression to maintain the same dynamic compression of a lessor cammed motor due to compression losses at overlap, once you're into the operating range (read powerband) of the cam those losses go away due to the momentum of the airstream. Proper exhaust scavenging will also be critical. What I'm really trying to say hear is that a high rpm/high HP NA motor is a package deal, everything needs to work together to pull it off sucessfully. Good luck on your project.

I agree with Rarly8 bout boosting
 

What about supercharging? Could he still do it at this point with those cams?

ok so I went and looked by the driver side door and the weight on my 1975 says 3086lbs and I looked for the 911 technical specs for that year and found this info: 1975 911 S (US), 911 Carrera S (US) 1100 kg which would be 2425lbs. Which one of these numbers is right? A 1975 can't be 3000lbs!?!?

--Michael

I believe the sticker on the door is GVW (Gross Vehicle Weight) this is the weight of the car plus full payload and passenger capacity not the weight of the car. Somewhere I have the actual figure but I seem to remember the '73 weighing around 2300-2600lbs.

john_cramers post with the facory specs should tell you what you can expect with a properly built 3.0

you can see 300 HP...... and a bit more if you stretch the envelope

realistically using cis or carbs you could get into the 230~250's

to get at the fringe of engine output you'd have to go 10.5:1 or better compression, use MFI or EFI and live on race gas,

free flowing exhaust would be mandatory

So you're saying, Warren, that the most to be expected from the mods are 14 to 16 hp at peak, 20 to 25 mid-range. So that's, what, 220 to 225 total, right? That can't be too bad for a 2300-2400 pound car, right?

I'm going to agree finally. With Warren (always a safe bet). I think my engine may be over 200 hp (stock was 180), but again, the real benefit is in low end torque and high end power as well. The stock engine used to make power only between 4000 and 5500 rpm. Now the power does not trail off at all...makes great power at 6500 rpm, actually. And is very fun to drive at 2500 or 3500 rpm. I'd believe a 25 hp improvement at 3300 rpm. But overall, peak horsepower, these mods probably make 200 horses or so.

Yes, a 230 hp engine in a 2300 lb car would be quite fun to drive. A good driver in a car like that is going to be pretty quick. Depending on tires, of course.

I will say this, the car is squirrlier now. I mean, I used to have to be careful with the throttle in 1st gear, expecially on wet. Now, I have to be quite careful in 1st always, and the tail can even kick out in second. I mean without dropping the clutch, just throttle.

Be happy with your car's power, at least for a while. Learn to drive it. You have a very quick car.

Anyone who says you CAN NOT get 400 hp out of a naturally aspirated 3.0 litre engine has not been around racing much. 3.0 litre engines have been producing over 600 hp for years. You can't do it by changing your air filter or exhaust or by replacing the coil. Also, if you want to get that kind of horsepower by just bolting something on the outside of the engine, turbo or superchargers are the only way to go. But when someone says it is impossible to get 400 hp out of a 3.0 litre, I beg to differ. It won't be something you want to drive on the street, but I think I mentioned that. It won't be built by a do-it- yourself shade tree mechanic in his backyard on Saturday afternoon either. But it can and has been done. You can't get more than about 250 hp out of a 3.0 below 7000 rpm either. It will take racing fuel but racing fuel alone won't do anything for you. The entire engine has to be modified beyond the comprehension of the average do-it yourself mechanic. By the way, there are motorcyles with stock engines less than 1 Litre producing over 140 hp. So engines are not limited to 100 hp per litre. Just take a look at the specs on some of the formula racing engines over the years.

The point being made hear is that there are limits to streetable horsepower in naturally aspirated and forced induction. I don't feel that requiring race gas can be considered streetable, I also don't feel that a car that shakes and coughs below 3000 rpm is streetable either. As for forced induction a car with a huge turbo and a lot of lag isn't all that streetable either. I made mention of a 500hp 302 that I had built which equates to 100hp/liter but it wasn't streetable by any means. I do feel that the 911 engine is capable of 90-100hp/liter in streetable trim due to the fact that it started life as a high performance engine and it's head configuration reflects this but hp levels that high will most likely be on the edge of streetablity. There is only one way to build huge HP figures from a NA engine (without increasing displacement) and that's with rpms. Everything needs to be maximize toward high rpm airflow the heads, valves, cams, intake system, and exhaust all neet to be capable of flowing a lot more air, the problem with this is airflow at lower rpm will be so slow that torque will suffer greatly and therefore driveability will suffer. Another requirement of high rpm HP is an "oversquare" engine (big bore, short stroke) this also hurts lowend torque. As HP and rpms are increased engine strain and wear increase exponentially, which is why race engines have such a short life span.

I think john_cramers factory power outputs (or thereabouts) are a pretty good idea of the maximum for a 2 valve per cylinder Porsche engine.

More is possible - there is a 370ish hp 3.4 here in New Zealand but this required:

- 10.5 c/r
- RSR cams
- 50mm TWM induction
- MoTeC M8
- big enough headers

This is thousands of dollars in parts alone, and probably represents what Porsche themselves would have done to the engine with modern technology.

My own (finished!) engine is a 3.0 with 98mm p&c for 3.2 (a 6.5% increase). It is twin plug, has 10.3:1 c/r and S cams with 40mm throttle bodies and ported heads etc. With SSIs and a regular muffler, I will be very very pleased with 270hp, or 85hp/litre. And yes, it is streetable (EFI, very light car). I will supply a dyno run next week after it is tuned properly.

Look at Porsche's own power claims - anything over 80hp/litre required S cams, eg:

- 204hp SC (higher compression - 9.3:1) 68hp/litre
- 231 (Euro) Carrera with 10.3 c/r (I think) - about 72 hp/litre

I just can't believe that you can depart too far from the result of S cams in the 3.0RS - 230hp with 9.3 c/r. Sorry. I am hoping for just 25 hp above that (ie 230hp + 6.5% to give 245hp, then gap to 270 is 25hp) from twin-plug and 1 point higher c/r , larger ports and throttle bodies and modern fuel management.

Also - the usual quoted weight for a '75 is 1075 kg without air con (2365lb).

Two other data points:

310hp from a short stroke 3.2 (thus 3164cc):
http://www.williams.co.nz/stallion.htm

Kurt Starnes 3.2 short stroke with RSR cams approx 300hp:
http://www.williams.co.nz/stallion.htm

Remember these are 3.2s - the equivalent 3.0 is 93.5% or only 280hp. I would assume these engines are on the edge of streetable.

Cameron - when you say without a.c.
 

...are you talking about a.c. in total, including the interior vents and the blower in the trunk's smuggler's box up front, or are you only counting the compressor on the engine and the condensor?

Thanks.

Cameron - just saw your other post --
 

the 3.0 is 93.5% of a 3.2 at what point? When it is short stroked to a 3.2 or stock? I'm not certain.

Thanks.

Cam, your engine sounds awesome.

I've been contemplating a 3+ltr MFI conversion for my car as a long term project - which should get the thing up and going.

Looking forward to hearing your seat of the pants impressions when you've got the car sorted.

Good luck.

Cam I'm dying to see this new engine in action. Nice setup :)

What I understand is that in 74/75 air con wasn't standard and the weight quoted reflects this. I think most of the weight increase to the SC was the air con (up from 1075 to 1160kg, although flares and wheels/tyres must have made a difference). I assume it is the whole system - lines and all.

Take this with a grain of salt - it is partly a guess, partly a vauge recollection of something I have read. The numbers are based on the info in the Cotton book "Original Porsche 911".

I checked the displacement numbers when I got home last night - I wasn't quite right on the displacements - note 3164 is Carrera displacement, 3186 is short stroke SC displacement:

3.0 SC with 95mm pistons and 70.4mm crank = 2994cc
3.2 SC with 98mm pistons = 3186cc (ie 6.5% bigger due to increase in piston size)
3.2 Carrera with 95mm pistons and 74.4mm crank = 3164cc (due to longer stroke)

Putting 98mm cylinders on a 74.4mm Carrera crank gives 3.4 litres.

Basically, the bore increases with the 98mm pistons and cylinders by 3mm. 3mm / 95mm = 3.16%. 3.16% squared (remember Pi*r^2 for area) gives 6.4% increase in area of piston top. Oooops, it is 6.4% not 6.5% ;). You get same result with 3186/2994 - 1.

Thinking again, to clarify, you could consider a standard 3.2 Carrera as a "long-stroke" 3.2 (74.4mm stroke) and a 3.0SC with 98mm pistons and cylinders as a "short stroke" 3.2 (70.4mm stroke).

My engine? Well, it runs but is running rich and needs tuning before driving any distance as too much fuel will impede the rings seating properly. It will get off the truck and straight on to the dyno in the next day or two.

First impressions (about 2km of driving) are that it is amazingly torquey and very fast.... below 4k revs or so. I can only begin to imagine what happens over 5k when the S cams start to do their thing.

I should have the car run in by the end of the month and can report then on full throttle and 7k rpm. I will hopefully have it safely back home by next week and can start driving!

Bill - I will try and make my merry way down to Wellington at some stage (roooooad trip) and will let you know :)

Although I am normally a very busy man, I will be sure to put by a couple of days spare to take over the running in chore Cam.
Usually wouldn't offer, but us Pelicanites should stick together, even in the hard, laborious times.

I feel my services would be of most use near the final, higher rpm break-in period, as that is my self appointed area of expertise.

Bill: you will have to wait :)