Greetings!

My 914 currently has a 1975 2.7 CIS installed. I have an option to change up to a 1978 3.0 CIS

I know the 3.0 is a better motor from the aluminum block / studs point of view, but it doesnt have much more HP or torque.

My questions are -

1) will there be a noticable performance inprovement?
2) is it worth it?
3) are there any simple inexpensive mods that can be done to gain more HP?

I intend to keep the injection system.

Cheers!

Sort of different engines. The 2.7 (if it's an "S") is a more peaky in it's power/rpm range with less torque. The 3.0 will have more bottom end with less on the top end if both are CIS, stock cam engines. If your 2.7 has been properly rebuilt, it probably wouldn't be worth pulling it for a 3.0. Your 2.7 has a lighter engine case, yes, weaker, but lighter by I think around 50lbs or so. Sort of your choice I guess.

If the 3.0 is in good shape, by all means go for it. The torque & power curves are very similar in CIS form, but the 3.0 has 18 cubic inches more of both. The longevity issue alone is worth it.....& I'm a 2.7L guy.

There is no inexpensive way to get a decent amount of HP increase out of either. Incremental increases are possible, but the bang for buck ratio is not good.

For $5/6K, (DIY), 50-60 more hp for either is there for the taking.

Check the torque on the 3.0 head nuts BEFORE you commit to buy. The 2.7's pulled studs out of the case, but the 3.0's are breaking head studs. I don't think that you'll see enough performance improvement to warrant the time and expense.
A '74 & '75 2.7 is rated at 150 DIN HP, an '80 3.0 is rated at 180 DIN HP. That's a 20% increase, so maybe it is worth it.

Yes it is an "S"

But - The motor (my 2.7) came out of a 911 that was imported from germany, then promptly crashed. Im told it "could" have more power than what was sent to north america.

Both are CIS

Thanks

What about this - ?

http://www.pelicanparts.com/techarticles/9...ne_rebuild2.htm

This seems not too pricey.

Thanks!

http://www.pelicanparts.com/911/technical_...hassis_info.htm

This is where I got my specs from. It looks like there is only 5 hp difference. Or is this sheet incorrect?

Cheers

I got mine from Bruce Anderson's 911 Performance Handbook, but it wasn't on a nice chart like that, I may have mis-read it. The way he lists the year to year changes is a little confusing.

I heard that the 3.0 suffered from an extremly restricted exhaust and that changing it to something more free flowing would gain you near 20 more ponies. Can anyone confirm this?


Also something interesting - I have 2 spare CIS systems in boxes in my garage. One is a 2.7 and the other is a 3.0. I noticed the aluminum intake pipes are much bigger on the 3.0 system. I wonder if you would get some hp gain by installing this larger air system on a 2.7, using a 2.7 fuel distributor and air flow meter of course. The air would certainly flow more free.

I don't now whatthe 3.0 is going to cost you BUT the 2.7 engiune is almost as good a base for a screamer as the 3.0. IMHO I would keep the 2.7 and use the 3.0 purchase $$ on the 2.7 as the power gain from one to the other to me just isn't worth the cost of a second engine. IF this was a later 3.0 SC engine I would have a different opinion FWIW my intention is to rebuild my SC with JE pistons, 964 cams and Clewett or most likely TWM injection. Looking at more like 260-270 H.P. I hope plus better appearance in the engine bay

http://www.twminduction.com/ThrottleBody/T...leBody3006.html


http://www.clewett.com/products/engnmgmt/emsys.htm#indivTB

I suffered the same quandry many years ago, and ended up just rebuilding my 2.7 to Bruce Anderson's specs (RS pistons/cylinders, E cams, dilivar studs, timecerts, carrera chain tensioners, etc.), and have found it to be a great, powerfull and reliable engine. It does rev freely and feels like you can jump on it more than a larger displacement engine. My 3.2 911 Carrera was a nice car, and the torque made it an easy drive around town, but it didn't have the kick of the 2.7. I think it is mainly due to the cams, but unless you're replacing the P/Cs and cams in the 3.0 engine, and going to carbs or another injection system,you might just as well keep the 2.7.

--><div class='quotetop'>QUOTE(scotty b @ Dec 9 2007, 06:04 PM) </div><div class='quotemain'><!--quotec-->
I don't now whatthe 3.0 is going to cost you BUT the 2.7 engiune is almost as good a base for a screamer as the 3.0. IMHO I would keep the 2.7 and use the 3.0 purchase $$ on the 2.7 as the power gain from one to the other to me just isn't worth the cost of a second engine. IF this was a later 3.0 SC engine I would have a different opinion FWIW my intention is to rebuild my SC with JE pistons, 964 cams and Clewett or most likely TWM injection. Looking at more like 260-270 H.P. I hope plus better appearance in the engine bay

http://www.twminduction.com/ThrottleBody/T...leBody3006.html


http://www.clewett.com/products/engnmgmt/emsys.htm#indivTB
[/quote]

You lost me. The 3.0 I can get IS an SC with CIS. The links you included here are for a 3.2 L jetronic. Or am I wrong?? Or is this a complete aftermarket injection system??

Cheers ( and confused )

Carbs - never!

What kind of shape is the 2.7 you have in? If it's good shape or has low miles, that might be worth just keeping it the car.

If you scroll down you will se that there are kits for any size 911 engine. They have the 3.2 at the top I assume because it is their best seller Clewett is the individual t.b. kit with a color pic. TWM you size the t.b. to your spec

To get the afore mentioned 50-60 hp you need pistons & cylinders ......to give clearance for your new cams, then carbs to make em' work.

The article you reference about raising compression only is for guys that need to pass smog & retain their CIS. Why anyone would go to this trouble for a non smog motor is beyond me.......964 cams are not a high performance grind and won't support more than 6500 rpms.
The cost difference is around 1500-2000 (a used but good Weber set up) for the carbs and the HP quoted is for a 3.0 not a 2.7.

My 2.7L is being rebuilt as we speak.....I'm nearly done, in fact.
With Webers, Solex cams, 10.4:1 P/Cs, and a bit of porting on the intake side, I'm expecting an honest 220HP with a nice wide power band ......3800 to 7300.
In a sub 1800 lb 914, that will get your attention.

Well, it got bearings, rings, valves and guides 400 miles ago.

Im not excited about the current level of crankcase pressure, but it doesnt smoke.
Im hoping the crank case pressure thing resolves itself with more milage.

<gulp>

This is one of the reason why Im considering the proven 3.0

I think it would be more worth while to go with a 3.2 same basic engine as a 3.0 but you gain the motronic injection. I am pretty sure that could be tweaked to take pmo or twm throttle bodies (speculation as I have not investigated).

I have a fresh 2.7 CIS engine and I rebuilt it using SC cams to flatten out the torque curve. I have liked it so far, and I just found that my increasing crankcase pressure and smoking was due to my #3 sylinder eating itself. No rings left and pieces missing. I am fixing it. I agree with the comments about the 2.7. Its a great engine once you take care of a few things.

Dont use dilivar studs, they are the OE ones proned to failure.