250 bhp from CIS ?

[911 tweaks]

+1 to Bill knows his sh^t !! I believe the max "economical ~ logical" hp one can get from a stk 3.0L CIS engine is to do the following:
1. 20/21 or 964 cams
2. ssi (header) exhaust
3. burn hi test gas and tweak the engine on a dyno to get max 210 ~ 230 hp at the flywheel w/ possible timing advance.
This is my understanding, and I am open to correction, but this I have learned from Bill and the likes here on the bbs.
*** plenty of options if you want to go another route i.e. bump up displacement; use aggressive cams & pistons; change to carbs or mech f/i or elect f/i; correct exhaust for what your set up is; upgrade brakes & suspension if to make a 300 hp engine and/or put in a 3.6 ect.
As the seemingly "they want to take all of your money" comment goes, what is your budget ~ how much do you want to spend, and the faster you want to go the more it will cost !!
**This last statement is the real truth... accept it likeingly or not !!
Good luck!
Bob

[911 tweaks]

+1 to Bill knows his sh^t !! I believe the max "economical ~ logical" hp one can get from a stk 3.0L CIS engine is to do the following:
1. 20/21 or 964 cams
2. ssi (header) exhaust
3. burn hi test gas and tweak the engine on a dyno to get max 210 ~ 230 hp at the flywheel w/ possible timing advance.
This is my understanding, and I am open to correction, but this I have learned from Bill and the likes here on the bbs.
*** plenty of options if you want to go another route i.e. bump up displacement; use aggressive cams & pistons; change to carbs or mech f/i or elect f/i; correct exhaust for what your set up is; upgrade brakes & suspension if to make a 300 hp engine and/or put in a 3.6 ect.
As the seemingly "they want to take all of your money" comment goes, what is your budget ~ how much do you want to spend, and the faster you want to go the more it will cost !!
**This last statement is the real truth... accept it likeingly or not !!
Good luck!
Bob

[DARISC]

Originally Posted by Bill Verburg

I don't hate it, it is what it is.

Oh, I know. I had hopes for getting mo powah from my '82 when I first bought it and your posts were helpful in putting those thoughts to rest - I'm in CA and I'm stuck with cis, which, incidentally, still works great on my daily driver after 198 k miles.

The one comment I've read/heard and never quite understood is that cis has poor throttle response. Mine, while I'm sure not the fastest, responds pretty fast, as I perceive it.

[safe]

Originally Posted by DARISC

The one comment I've read/heard and never quite understood is that cis has poor throttle response. Mine, while I'm sure not the fastest, responds pretty fast, as I perceive it.

+1
Mine is pretty snappy, maybe not like carbs on 2.4, but it beats the crap out of any stock motronic.

Ps.
+1 to Bill knows his sh^t !!

[davidbir]

Originally Posted by DARISC

To all on this thread (who don't already know this):

Re Bill Verburg; I know, I know - the guy's only got a few more than 14,000 posts and sounds sooooo logical and well informed! Well, you know how the internet is; you can be anybody you say you are, moderator, have tons of knowledge and experience, yada yada yada...

The problem with the vaunted Mr. Verburg is......he DOES have tons of knowledge and experience (and a fair ammount of yada yada too).

This whole CIS thing has been through the wringer here many times over the years and as far back as I've been looking in here, this Verburg character has patiently explained "about CIS", repeatedly.

Lively discussion can be fun and edifying, but in this case, Bill Verburg's input is the definitive stuff (incontrovertible).

PS - I think he hates CIS.

As a newbie I realise I have to be careful of getting off on the wrong foot (Carfax--Doh!) . And I realise Mr Verberg has far more knowledge of Porsche than I will ever have.
BUT, over 2000 views of this post after just a few days!
Don't ever stop looking for solutions!

[Kemo]

Ok...so...If I had a Stock Euro SC and I added a killer exhaust system like SSI's and an MK muffler, and then I had the car dyno tuned for max HP...what would that HP be?

From this thread it seems that the Euro SC has really good potential as compared to the USA version...

Also, are there other differences with the Euro vs USA model?

So far, my list includes:
Larger intake runners and ports
Higher Compression
Larger Fuel Distributor

What else? Transmission gearing? WUR?

[Superman]

I'm not going to read though all this threads but I'm fairly sure of what I would find. We all envision 260 hp and some folks have made themselves believe this but in reality, a 3L engine can pump only so much air. My late-SC (9.3:1 CR) engine, freshened, with 20/21 cams and early heat exchangers (from a '73) made 174 lb/ft of torque at the rear wheels as measured on a chassis dyno. There were several other similar 911's there including a 3.2 Carrera and this 174 lb/ft of torque was the most any car made that day. It translates to about 205 lb/ft at the flywheel. That's an increase of at least 25 lb/ft over stock. You guys that think 3L engines can make 230 hp without fairly serious internal engine mods......are dreamin'.

I have been told that since CIS systems have an air flow sensor plate in the intake plenum, their air volume is more limited than with carbs. Okay, I believe that. But carbs are not going to make THAT much difference. They will feel much better in terms of throttle response (CIS absolutely SUCKS for throttle response), but the actual horsepower increase with carbs is not going to be massive. CIS systems, when working properly, meter and atomize fuel at least as well as any carb.

Flame on, but don't pretend you can bolt a new exhaust on your 3L engine and increase hp by 50. HP for USA 3L's was actually 174 DIN, or something like that. So.....a 50-hp gain would put you at 124. There is no way you're going to get that with exhaust and cams.

[Superman]

Originally Posted by Kemo

Ok...so...If I had a Stock Euro SC and I added a killer exhaust system like SSI's and an MK muffler, and then I had the car dyno tuned for max HP...what would that HP be?

From this thread it seems that the Euro SC has really good potential as compared to the USA version...

Also, are there other differences with the Euro vs USA model?

So far, my list includes:
Larger intake runners and ports
Higher Compression
Larger Fuel Distributor

What else? Transmission gearing? WUR?

If you start with a late SC Euro engine (9.8:1 CR) and transplant heads and intake system from an earlier SC, plus 20/21 cams and SSI exhaust....then I think you might get into the 230-240 hp area.

But again, if you want to get substantially past 250 hp, then you're going to need more than 3000 cc's.

[Kemo]

I think i could live with 230-240 HP! So I guess thats what the PCA 'D' Class, Euro SC's are putting down. No wonder they do so well on the track.

[911st]

If you want to make big HP w cis it takes cubic inches and the fuel system can support up to 300hp with out a problem.

If it is going to stay a 3.0 then if you tune it right and get 210-220 fwhp +/- you have a great motor.

Want more, lighten the car and learn to drive.

A light weight well tuned 3.0/CIS is a great car and can be faster than a 73 RS touring in the right hands.

I am not a great driver but I recall a set up & modified fire breathing 930 that had to let me by at a track event in my little 72 911S.

If you have to take the motor apart think of just selling it off and buy a turn key 3.2, it will be cheaper, more fuel efficient and can make great power (230+).

Other wise if you are in there already and have a few extra dollars, bump the compression, add cams and you will broaden the power band and add a bit more HP.

Look into the euro WUR/CPR for an enrichment circuit. If it has this, it will make the car more responsive. Getting the timing / advance curve right can help to.

Call it what you want, there is no real need to change out the fuel distributor/head to a Euro set up to make power on an SC. Just proper set up & tunning.

Just my unexpert opinions.

[Gary.H]

Originally Posted by Superman

I'm not going to read though all this threads but I'm fairly sure of what I would find....You guys that think 3L engines can make 230 hp without fairly serious internal engine mods......are dreamin'....Flame on, but don't pretend you can bolt a new exhaust on your 3L engine and increase hp by 50. HP for USA 3L's was actually 174 DIN, or something like that. So.....a 50-hp gain would put you at 124. There is no way you're going to get that with exhaust and cams.

Maybe you 'should' read the thread mate ?

[safe]

Bruce Andersson states that an early exhaust is good for an extra 17-22 hp.
I'm guessing that is for a US spec car, I doubt that number for a late euro engine.

My euro 2.7 WUR has a vacuum connection that alters the control pressure depending on the vacuum.

[davidbir]

Oh dear, it's the Brits vs the Yanks again

Anyone in the mood for a little levity?


MESSAGE from John Cleese - British comedian -- to the citizens of the United States of America :

In light of your failure in recent years to nominate competent
candidates for President of the USA and thus to govern yourselves, we
hereby give notice of the revocation of your independence, effective
immediately.

Her Sovereign Majesty Queen Elizabeth II will resume monarchical duties over all states, commonwealths, and territories (except Kansas , which she does not fancy).

Your new Prime Minister, Gordon Brown, will appoint a Governor for
America without the need for further elections. Congress and the Senate will be disbanded.

A questionnaire may be circulated next year to determine whether any of you noticed.
To aid in the transition to a British Crown Dependency, the following
rules are introduced with immediate effect:

1. You should look up "revocation" in the Oxford English Dictionary.

2. Then look up aluminium, and check the pronunciation guide. You will be amazed at just how wrongly you have been pronouncing it.

3. The letter 'U' will be reinstated in words such as 'colour', 'favour'
and 'neighbour.' Likewise, you will learn to spell 'doughnut' without
skipping half the letters, and the suffix '-ize' will be replaced by the
suffix '-ise'. Generally, you will be expected to raise your vocabulary to acceptable levels. (look up 'vocabulary').

4. Using the same twenty-seven words interspersed with filler noises
such as "like" and "you know" is an unacceptable and inefficient form of communication. There is no such thing as US English. We will let
Microsoft know on your behalf. Th e Microsoft spell-checker will be
adjusted to take account of the reinstated letter 'u' and the
elimination of -ize.

5. July 4th will no longer be celebrated as a holiday.

6. You will learn to resolve personal issues without using guns,
lawyers, or therapists. The fact that you need so many lawyers and
therapists shows that you're not adult enough to be independent. Guns
should only be handled by adults. If you're not adult enough to sort
things out without suing someone or speaking to a therapist then you're
not grown up enough to handle a gun.

7. Therefore, you will no longer be allowed to own or carry anything
more dangerous than a vegetable peeler. A permit will be required if you wish to carry a vegetable peeler in public.

8. All intersections will be replaced with roundabouts, and you will
start driving on the left with immediate effect. At the same time, you
will go metric with immediate effect an d without the benefit of
conversion tables. Both roundabouts and metrication will help you
understand the British sense of humour

9. The Former USA will adopt UK prices on petrol (which you have been calling gasoline) -- roughly $8/US gallon. Get used to it.

10. You will learn to make real chips. Those things you call French fries
are not real chips, and those things you insist on calling potato chips
are properly called crisps. Real chips are thick cut, fried in animal
fat, and dressed not with catsup but with vinegar.

11. The cold tasteless stuff you insist on calling beer is not actually
beer at all. Henceforth, only proper British Bitter will be referred to
as beer, and European brews of known and accepted provenance wil l be referred to as Lager. South African beer is also acceptable as they are pound for pound the greatest sporting Nation on earth and it can only be due to the beer. They are also part of British Commo nwealth - see what it did for them. American brands will be referred to as Near-Frozen Gnat's Urine, so that all can be sold without risk of further confusion.

12. Hollywood will be required occasionally to cast English actors as
good guys. Hollywood will also be required to cast English actors to
play English characters. Watching Andie Macdowell attempt English
dialogue in Four Weddings and a Funeral was an experience akin to having one's ears removed with a cheese grater.

13. You will cease playing American football. There is only one kind of
proper football; you call it soccer. Those of you brave enough will, in
time, be allowed to play rugby (which has some similarities to American
football, but does not involve stopping for a rest every twenty seconds
or wearing full kevlar body armour like a bunch of nancies). Don't try
Rugby - the South Africans and Kiwis will thrash you, like they
regularly thrash us.

14. Further, you will stop playing baseball. It is not reasonable to
host an event called the World Series for a game w hich is not played
outside of America . Since only 21% of you are aware that there is a
world beyond your borders, your error is understandable. You will learn
cricket, and we will let you face the South Africans first to take the
sting out of their deliveries.

15. You must tell us who killed JFK. It's been driving us mad.

16. An internal revenue agent (i.e. tax collector) from Her Majesty's
Government will be with you shortly to ensure the acquisition of all
monies due (backdated to 1776).

17. Daily Tea Time begins promptly at 4 pm with proper cups, with
saucers.

No mention of CIS

[DARISC]

Originally Posted by Superman

If you start with a late SC Euro engine (9.8:1 CR) and transplant heads and intake system from an earlier SC, plus 20/21 cams and SSI exhaust....then I think you might get into the 230-240 hp area.

I posted earlier that I THINK my '82 RoW with SSIs and Dansk 2 in/2/out got a boost from the factory 204 hp, to maybe 220-223 hp. Dunno what % loss to rear wheels.

What I hesitated to say is that I then spent $69.95 on one of those Tornado devices (TV infomercials are great!) that straighten the air and hasten it through the intake (cis HATES crooked air!).

I ended up taking it off after about a week. I never had it dynoed so can't really say how much mo powah it gave me, but if I pushed down too hard on the petrol pedal the front wheels wanted to come off the ground which made steering feel very iffy.

I still have it and will sell it for $65.00 even, if you've got the driving skills and courage to handle the power.

[911 tweaks]

that was "spot on" would'nt you say ?
LOL

[Wil Ferch]

Ahh.... Gary.H ...... the dyno chart proves nothing.... to whit-->

1.) is the HP at the crank or at the wheels?....
2.) is it "raw" hp as seen THAT day with THAT DAY's temp, altitude, and Relative Humidity....or is it ( like some dyno's are capable of reading) , "normalized" to a "standard" set of conditions...such that it can be COMPARED to other, likewise normalized graphs? Example: chart can be set up to read SAE-Standard HP. There is usually a "CF" shown on the bottom of such dyno charts...a "correction factor". I've been able to match different cars pretty well ...some at sea level and some at Mile high locations.....by seeing and using the CF factor that was listed for SAE-corrected curves.

A dyno chart as listed w/o these details is plain useless......

[Superman]

Originally Posted by Gary.H

Maybe you 'should' read the thread mate ?

Indeed. Like Will said, this chart raises more questions than it answers. You can tell me your stock 3L makes 275 hp and perhaps you could produce a chart, but it still wouldn't make it true.

(I notice the chart says this dyno run was done in third gear. I wish they had let me use third gear. They specified that fifth gear was to be used, since that is the closest to 1:1 input/output ratio.

As I say......lots of variables and lots of questions. When guys claim 240 hp with a USA 3L that's got nothing more than cams and SSI, I call "bull****."

[RarlyL8]

Before scrapping the idea of getting any meaningful power out of my '78 Euro 3.0L SC engine I did about all you can do to one while still retaining the CIS.

It ain't much.

Cams, SSIs, a good muffler, thorough tweak of the CIS is about all you can do. The result?
191WHP (225CHP @ 15% loss). Not terribly exciting.

[dd74]

CIS? 250? Why? CIS is very reliable in stock form when it works well. I really wouldn't mess with a stock 3.0 just for the sake of making it faster with CIS. CIS is simple and has very good throttle response. Plus if something does go wrong, most Porsche mechanics know how to fix CIS. But it's not going to allow you to bring 70 more hp over stock. For that, your options are either to build a motor or buy a 3.6.

To be honest, beyond the diminishing returns of engine modifications, I'd think you'd be better off lightening the car and sticking in a shorter gearbox. At that point, it won't matter if you have only 180 hp. Your car will be much faster and still smog legal.

Here's my 3.0's dyno rating.

It was an '83 with '74 exhaust. It was very healthy and my car quite fast. But my car also weighed below 2,400 and has shorter gears than an SC.

Here's a thread where a guy received about 230 hp from his SC with CIS. Nice, though again, dyno readings have a habit of being inaccurate.

Dyno'd the SC yesterday

[MrPerkles]

In defence of GaryH his car was dynoed with several other well known 911s that day who have had lots of dyno time ,mine was also done and way down on power.I have no reason to believe after seeing the way Garys car goes that his HPs figures arent correct