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3.0 Liter upgrade horsepower

I'm looking for about 230 hp with an upgraded 3.0L In Wayne's book he says you can get between 30-50 horsepower with higher compression pistons and SSI heat exchangers.

I already have European headers and a 2 in 2 out M&K muffler on my 2.7 with weber carbs, what more do I need to add to a rebuilt 3.0 to get 230 hp?

Kent
Old 03-15-2007, 08:53 AM
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Can you do a top end rebuild on a 2.7 to 3.0? I don't know if the pistons and cylinders would just be bolt on. The 2.7 crankcase is magnesium and you would need to time-cert the case or the head studs will pull out. That would be a big job. You would need to switch to the 964 cams if you want Wayne's engine, but that was a 3.0 aluminum block, not a 2.7. The SSI's would just bolt on to the headers.
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Old 03-15-2007, 11:03 AM
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You don't need anything else. Even with 8.5 pistons and small ports you'll get your 230 HP. If you have 9.3 or 9.8 pistons and big ports 240 to 250 HP is possible (46mm carbs for the higher number).

-Andy
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Old 03-15-2007, 12:53 PM
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Thanks, that's what I was wondering. I'm planning to find a 3.0L , set it up on a engine stand in my shop, take it apart and rebuild it back to about 230hp.

Then I'll pull my 2.7L , swap the hyd chain tensioners, European headers/M&K muffler and my intakes and rebuilt webers.

I understand the crank must be checked but they are normally ok. The case should be ok. Then the safest thing is to replace all pistons and cylinders. The question is 95mm or 98mm. Cost will probably be the issue.

I understand the 78-79 cylinder heads are larger than the later heads. I've been told the smaller heads will provide more low end torque which I feel, is more important in a street application.

As far as a cam I have heard of "S", 964, and Solex. I guess I need an expert to help me make that decision.

I'm hoping to have this done before the end of the summer so I can play with the old girl before the warm weather is gone. I have no heater, since I went to headers, so I don't drive her as much anymore but anytime the sun is out I'm out even if I need a big coat.

206,000 miles and counting.

Kent Olsen
Old 03-15-2007, 09:35 PM
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I too would like to see a summary. I have a nice old (40K mi) ’79 3.0 setting around that should come back to life.

I agree with SSI and high compression. I understand 964 cams are suitable. I don’t know of any “wilder” cams that are still suitable for use with CIS. Certainly high overlap cams (T, E, Solex, S) aren’t suitable for use with CIS. There are some choices of intake runner diameters. What performance (or detriment) does the cold start distributor inside the air box starting in ’81. With high compression I would add 12 mm exhaust spark plugs for twin ignition. I think 98 mm P&Cs bolt on to make a “short stroke 3.2” (98x70.4).

What is the limit of the 3.0 CIS? (The 260 hp ’75 Turbo uses the 8-cylinder CIS.)

Some of the “while you are there” might be to replace the cylinder studs. What else? I feel the 1.82:1 fan ratio is number one. Probably a full-fin front cooler is a close second. I am a firm believer in increasing the oil flow to the heads and valve train. That is done with using both the spray bar and center oiling cams similar to the 911SCRS. Another is increased oil flow to the underside of the pistons. Both of these benefit from the larger oil pumps available.

Even though these aren’t high revving engines, every engine benefits from improved crankcase “windage”. The little 964 check valve in the breather system seems obvious. Another is to reduce the pumping friction in the crankcase. The easiest here is opening the cylinder spigots and case webs.

This seems a good compromise performance increase, particularly in areas with strict emissions requirements. It should be reasonably clean and acceptable mileage. For emissions tests the cat and air pump could be reinstalled – an easy Saturday project.

Best,
Grady
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Old 03-16-2007, 09:05 AM
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grady i think you missed that he already is using webers.

by european headers do you mean georges european racing headers?
what size of webers are you using? 40's of 46's.

the large port heads on the 78-79 are deifently a good thing. and with webers and nice headers (which i think you have) i would go with an S cam.

and with that list you have defiently met your goal, if you go with the 3.2SS you will exceed you goal

cheers
Nick
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Old 03-16-2007, 10:17 AM
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Quote:
Originally posted by Grady Clay
I too would like to see a summary. I have a nice old (40K mi) ’79 3.0 setting around that should come back to life.

I agree with SSI and high compression. I understand 964 cams are suitable. I don’t know of any “wilder” cams that are still suitable for use with CIS. Certainly high overlap cams (T, E, Solex, S) aren’t suitable for use with CIS. There are some choices of intake runner diameters. What performance (or detriment) does the cold start distributor inside the air box starting in ’81. With high compression I would add 12 mm exhaust spark plugs for twin ignition. I think 98 mm P&Cs bolt on to make a “short stroke 3.2” (98x70.4).

What is the limit of the 3.0 CIS? (The 260 hp ’75 Turbo uses the 8-cylinder CIS.)

Some of the “while you are there” might be to replace the cylinder studs. What else? I feel the 1.82:1 fan ratio is number one. Probably a full-fin front cooler is a close second. I am a firm believer in increasing the oil flow to the heads and valve train. That is done with using both the spray bar and center oiling cams similar to the 911SCRS. Another is increased oil flow to the underside of the pistons. Both of these benefit from the larger oil pumps available.

Even though these aren’t high revving engines, every engine benefits from improved crankcase “windage”. The little 964 check valve in the breather system seems obvious. Another is to reduce the pumping friction in the crankcase. The easiest here is opening the cylinder spigots and case webs.

This seems a good compromise performance increase, particularly in areas with strict emissions requirements. It should be reasonably clean and acceptable mileage. For emissions tests the cat and air pump could be reinstalled – an easy Saturday project.

Best,
Grady
so are you suggesting not running cam line restrictors??
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Old 03-16-2007, 12:15 PM
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Quote:
The little 964 check valve in the breather system seems obvious.
Grady, do tell! What is this all about?
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Old 03-16-2007, 12:17 PM
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Please fill us in Grady

In regards to camshafts, Grady brings up a point if not directly. Are you keeping the CIS pistons? If so you won't get much more cam installed anyway.

The 9.3:1 pistons with 20/21 will get you 230 even with small heads. and about 180ftlbs at the wheels. If you go with some JE's then you obviously can get more aggressive with the lift. I'd go aftermarket grind before S grind IMHO. I don't think you'll need/want to spin the 3.0 like a 2.0 on the street. Less duration, more lift, more overlap are all prefered over the S on the street I would think.
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Old 03-16-2007, 02:41 PM
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Nick,

grady i think you missed that he already is using webers.

You are correct, dumb ol’ me. I missed he was going to use the Webers from the 2.7 on the 3.0.

Many, for class reasons or emissions want to keep the CIS. My question was toward that configuration.

With Webers, I would use the early S cams (GE60). This will give exciting power to about 7000 rpm. With a 3.0 the choice of 40 mm vs. 46 mm is almost a toss-up. This is where use will determine the choice. With a 3.2 and larger, I would use the 46 mm. In either case you have a wide choice of venturi size.

In about ‘80 we built a 3.5S (74x100 mm parts from Frau Baer) and tried 40 IDAs. We couldn’t get 46s on fast enough.




Ben, “so are you suggesting not running cam line restrictors??

Absolutely.

In my opinion this was a “fix” that Porsche did picking the lesser of two evils. The issue stems from the ability of an SC or Carrera being comfortable to drive at 2000 rpm and sometimes less. The piston squirters are necessary to keep the pistons cool. However they don’t open until 42-56 psi. With full flow to the cams, the main oil pressure at the squirters was too low. They didn’t open until the engine was above 5000 rpm when hot – too late.

Porsche’s “solution” was to limit (restrict) the oil flow to the cams, rockers and all the parts in the top end. Note this also includes valve guides. Of course the restrictor raises the pressure in the main galley that feeds the piston squirters. They then open at lower rpm. The problem, IMHO, is there was already marginal oil to the valve train when hot and low rpm. The restrictor exacerbated the problem

I think Porsche chose to improve the piston cooling at the (evil) expense of valve train lubrication and cooling.

I’m not willing to build a nice engine with any preventable shortcoming.




Quote:
The little 964 check valve in the breather system seems obvious.
Grady, do tell! What is this all about?

Ron, High rpm engines benefit from low atmospheric pressure inside the crankcase. I have written previously about this. The short answer is the lack of air allows the oil to fall out of suspension quicker. This lowers the air-oil density on the backside of the piston, reducing the forces working against producing power. The little 964 check valve allows pressure pulses to pass from the case to the tank but seals and prevents return air.

Think of a 911 engine as three horizontally opposed 2-cylinder engines, each offset by 120° on the crankshaft. When the opposing pair of pistons are coming down toward BDC, the air-oil atmosphere has to go somewhere. The less there is and the easier it is to move to adjoining cylinders, the less lost power simply pumping air-oil around inside the engine.

Best,
Grady
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Hmmm,ok so are you suggesting that this is something that I should be installing in my 3.2 SS? I looked for this little devil in the PET and couldn't find it. Also would this be to the restrictor that is in place?
As for the restrictors..I had them installed and enjoyed the 2 bar pressures at idle but was really uncomfortable with the pegged meter at speed. I pulled them out and opened them up splitting the difference between the original openings and the restrictors.
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Old 03-16-2007, 05:28 PM
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Quote:
Originally posted by Grady Clay
"so are you suggesting not running cam line restrictors??

Absolutely.

In my opinion this was a “fix” that Porsche did picking the lesser of two evils. The issue stems from the ability of an SC or Carrera being comfortable to drive at 2000 rpm and sometimes less. The piston squirters are necessary to keep the pistons cool. However they don’t open until 42-56 psi. With full flow to the cams, the main oil pressure at the squirters was too low. They didn’t open until the engine was above 5000 rpm when hot – too late.

Porsche’s “solution” was to limit (restrict) the oil flow to the cams, rockers and all the parts in the top end. Note this also includes valve guides. Of course the restrictor raises the pressure in the main galley that feeds the piston squirters. They then open at lower rpm. The problem, IMHO, is there was already marginal oil to the valve train when hot and low rpm. The restrictor exacerbated the problem

I think Porsche chose to improve the piston cooling at the (evil) expense of valve train lubrication and cooling.

I’m not willing to build a nice engine with any preventable shortcoming.

Grady,

Thanks. I like the explaination of what the restrictors do and why the choice was made.

I have never been a fan of the restrictors without understanding why it was a good thing to reduce oil flow to the hottest, most stressed part of the engine.

But I do have a follow-on question? When the Porsche Engineers decided to install the flow restrictors to increase the bottom oil pressure to get the piston squirters to come on line sooner, did they also increase the capacity of the oil pump to compensate for the decreased flow to the heads?
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Old 03-18-2007, 09:17 AM
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Quote:
Originally posted by Grady Clay
Ben, “so are you suggesting not running cam line restrictors??

Absolutely.

In my opinion this was a “fix” that Porsche did picking the lesser of two evils. The issue stems from the ability of an SC or Carrera being comfortable to drive at 2000 rpm and sometimes less. The piston squirters are necessary to keep the pistons cool. However they don’t open until 42-56 psi. With full flow to the cams, the main oil pressure at the squirters was too low. They didn’t open until the engine was above 5000 rpm when hot – too late.

Porsche’s “solution” was to limit (restrict) the oil flow to the cams, rockers and all the parts in the top end. Note this also includes valve guides. Of course the restrictor raises the pressure in the main galley that feeds the piston squirters. They then open at lower rpm. The problem, IMHO, is there was already marginal oil to the valve train when hot and low rpm. The restrictor exacerbated the problem

I think Porsche chose to improve the piston cooling at the (evil) expense of valve train lubrication and cooling.

I’m not willing to build a nice engine with any preventable shortcoming.

Grady [/B]
I'm in total, complete agreement with Grady on this issue.

Some of the hottest parts of the engine are in the heads and its totally counterintuitive to REDUCE oil volume & flow to these areas that need all the cooling and lubrication they can get.

Personally, I will not use the cam line restrictors and in fact, prefer to upgrade oil pumps where feasible. In addition to Grady's comments about power, improving oil scavenge in the sump by using either the 930 or GT-3R oil pump reduces oil temps and helps power output by keeping the oil level in the sump well below the spinning crankshaft.
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Old 03-18-2007, 11:38 AM
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Since the "standard" fittings are not available anymore, it may be easier for people (such as myself now that I understand this mod) to drill out the restricted fittings.

What is the diameter of the original vs. the "new restricted" fittings?
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Old 03-19-2007, 06:18 AM
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Thanks for all your replys.

I'm presently building a ramp into my little barn to get the Porsche into. My shop is on the end of the little barn.

The 2.7L currently in my 72T made about 190-195 hp on the dyno before I left Orlando and thats with 40mm webers, George's European headers and Ben's 2 in 2 out M&K muffler.

Once I build up a 3.0L I'll be parting out the 2.7L.

Kent Olsen
Old 03-30-2007, 12:02 PM
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3.0 Power

Kent,
I have a 3.0 that should head do the dyno in the next week or two. Here's the build:

95mm Mahle's 10:1
Ported head (38.5 intake I beleive)
Webcam 120/104 cams
46mm PMO's
Electromitive single plug ignition
Race Gas

Looking for 215RWHP - hoping it's not more
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Old 03-30-2007, 01:36 PM
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Guys,

What happened to the poster who suggested we consult some “Real” engine builders? I oversaw more than 1000 911 engine builds. Some very radical for their day. Ask Pelican rs911t who still drives a 2.8S built in ’74.

In the past week I poled 14 builders nationwide that I consider the “best experts” (certainly not even close to all). Without exception all agreed with my assertion.

There was brought up an additional indication supporting my contention.

Porsche changed the low oil pressure warning light switch from 0.5-0.7 bar to 0.3-0.5 bar. Their contention is that was also for ‘political’ reasons – customers were complaining to Dealers that the oil light was “flickering” at idle when hot.

While it is understandable that our Beloved Manufacturer would do these things for “customer relations” reasons, we shouldn’t overlook all the technical issues.

We have the benefit of hindsight that the Factory engineers didn’t when engineering and built our 911s. We can build a ’65, ’73, ’83, ’89 engine better today than original. Some of that is because we are not in a manufacture environment. In many cases (track cars) we don’t have to follow ANY regulations. Mostly we have the benefit of hindsight. We have the choice to add more oil circulation (or less). We can choose the oil pressure our engines run (1.0 to 200 psi), independent of what anyone says (not that we would choose either extreme). The point is we can build a better engine today than Porsche did originally – no fault of their’s.


SO, - - -
Let me re-state my postulate:
More oil to the cam housing is better than less. The main oil pressure needs to stay above the point where the pistons squirters open. Excess crankcase scavenging (and other tricks) that reduce the crankcase pressure are to the benefit of power.


How do we do this?

Certainly not by restricting oil flow to the cams.

The proper way is with the largest possible oil pump. Today that seems to be the 3-section GT3 pump. A close second is the (more expensive) Turbo pump. Either can be fitted to every 911 engine from ’65 (with slight mod).

I haven’t surveyed the availability of current cam profiles with center-oiling. I suspect that this is an easy mod (Porsche did it with SCRS). This allows both center-oiling and spray-bar oiling.


Please let’s have some other info. I don’t have a problem with contrary views. In fact, I welcome them. That is how [b]I[/i] learn.

Best,
Grady
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Old 03-30-2007, 02:48 PM
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Steve and Grady,

When I rebuilt my engine I put the new cam line restrictors on due to Porsche and what I read on the board here. I didn't have a problem with oil pressure before the rebuild. So should I remove these and put my old ones back on since I will be dropping the engine again in a week? Confused (doesn't take much anymore) as this seems to be contrary to what I have read. This is in a 88 Carrera and rarely driven with low rpm's. And have no problems putting the old back on if it would be better. I will assume both of you would recommend the old cam line fittings.
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Old 03-30-2007, 05:44 PM
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I'm not as hard core about these fittings as Grady and Steve are but I don't have the experience they do either. My own experience with them was to try to help an oil starvation problem at the track. I was getting fluctuations on the oil pressure at the track and was hoping that the restrictors would cause less oil to collect in the heads and keep more in the tank. I found no improvement with the restrictors and I was uncomfortable with how high the oil pressure was at high RPM. I
removed the restrictors after that.

There are many builders that use them and I haven't heard of any problems that can be attributed to them. I wouldn't be worried about keeping them in if you are happy with the oil pressures you are seeing.

-Andy
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Old 03-30-2007, 08:40 PM
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Andy,

My oil pressure is maxed at 5 bar at anything above 3200 rpm hot. After reading this I am definately leaning towards going back to the old ones.

Thanks
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