Ok, lets talk 2.7

[Dan Mc Intyre]

Hi Gang,

I know many here don't really appreciate the appeal of mid-year P-cars or the 2.7's that go along with them. But a recent 2.7 thread has emboldened me to post this. It seems I'm not the only person to love the mid-year. I felt so ostracized!!

It was suggested to me that it may be possible to get near 200 crank HP from my 2.7 while keeping my CIS system intact.

I've reviewed Wayne's favorite engines section in his book and he lists a 2.7 using higher compression pistons and 964 cams. I did not, however, see a HP figure associated with that configuration. Even more intriguing was the statement that some people may argue that a 2.7 may be quicker than a 3.0 with similar mods!??

Of course, being mine is a 77, I realize the need to install SSI's and a new muffler and ditch the thermal reactors. But given those mods, does anybody now where the HP might come in? Or what, in addition to those mods, might I have to do to reach that figure? Does anybody have a 2.7 set up in a similar configuration and can share your experience with me? Are you happy with it, etc?

Thanks in advance for the input.

Dan

[Halm]

Dan, a 2.7 with RS style P&C's, a "S" cam and properly setup carbs should make 195-210 depending on exhaust and exact CR. I have no idea what a CIS motor is capable of making.

[Dan Mc Intyre]

Hal,

I was kind of thinking about that stuff in the back of my mind when I read the suggestion that I could possibly reach 200 with CIS. From what I've read here, 210 is about as good as it gets with carbs and the "S" cam. But...I'm pretty far from an expert and there are certainly people here that are better informed than I.

So, I thought I'd give it a shot. Carbs don't scare me as I'm old enough to have learned to drive in non-FI cars. But...I didn't drive a carb'd car sans choke. That gives me pause. Particurlarly in WI in October.

Dan

[2.7RACER]

The 2.7's cams run on three bearings. 964's use four bearings. This means using a newer cam tower or getting a three bearing cam reground.
Higher compression pistons, say JE's 9.5:1 and improved exhaust, SSI's or backdate to '74 and you should see 25 to 40 HP increase.
Since the '74's thru '77's are lighter cars, as much as 150 pounds, performance will approach that of a 3.0 SC.
Another upgrade is switching out the ring and pinion from 8:31 to the earlier 7:31. You'll get better accelleration at the expense of MPG.
You can always get more power from carbs and a hotter cam, but smog issues begin to rear their ugly heads.
Carbs can be an issue in the cold Wisconsin winters. They sure are here in New Mexico.
Bottom line, you can hot rod the 2.7 up to a point, beyond that go for the bigger cubes.

[Dan Mc Intyre]

Hi Doug,

I guess I should have phrased the part about cams better. I understood from the research I've done here that there is a difference between number of bearings and the need to regrind the cam profile.

However, if I gain 25 HP from the mods I propose gets me to about 190. That's in the ball park. I don't have smog Nazi's to contend with here so that's not an issue for me here. That's one benefit to living in the wilds of WI.

From what I read here, the use of a 964 profile will not really increase HP, but rather moves it higher in the rev range. My car seems to run out of breath over 5500 and I'd like it to rev better. So the cam change seems like a good idea. Do you know if a 964 cam profile will totally kill performance from 3000 to 5000 rpm?

I'm also pretty interested in the R/P change from my 8:31 to 7:31. I'm approaching this little project as a system. I've read that a properly set up tranny feels like a 50 HP gain. So...if a guy goes to the 7:31 gears, is there still a benefit to changing tranny gears and making it a close ratio set up? What is first gear like with 7:31's , does it turn into a granny gear? Fuel mileage is not a big issue here, either. I just want it to scoot up to about 100 mph. My idea is to leave 5th gear stock for interstate use. Also, with the HP increase and gearing change, how important would it be to swap out my open differential? This car will probably never see the track, but is driven somewhat aggressively on the street. How hard is it to find a used 7:31 tranny? Are they commonly available?

Thanks for the info, Doug.

Dan

[Dan Mc Intyre]

bump for more input.

[sketchers356]

Note that while the early S cams will give you alot more revving of an engine, they will not work with the CIS pistons (valve collision). So you would want to change the pistons to RS spec. Doing such will also give you a more sporting compression. Also, the overlap on the early S cam will not bode well with CIS. So if you want to go that way you will have to look for a new induction system. Anyway, Im planning on doing a hotrod 2.7 myself: twin plug, early s style cams, rs high compression cylinders, and a custom EFI system.

[Dan Mc Intyre]

Alexander-

It sounds like you'll have the engine I really want. But...I'm trying to keep some sort of budget on my project. If it weren't for the drawbacks of carbs, I'd go for it, S cams and all. I just don't want to deal with cold starting issues.

Now ITB's really are the way I'd like to go. But from what I read here, admission to that party costs $6 g's or better. That's a lot for induction. But man, I bet they run hard set up like that.

The whole purpose for me keeping my 2.7 is that I don't have to spend $4000 on a used 3.0 to build. I can think of much better ways to spend the 4k on my car, like my tranny!! Same for the ITB's.

Like I said, it was suggested to me that it may be possible to get near 200 HP keeping my CIS. So I figured I'd explore that thought. That combined with a close ratio tranny, maybe with a 7:31 ring and pinion, should make it plenty quick for my needs.

Good luck with your project. It sounds like fun.

Dan

[Halm]

Dan, I think you may be over doing the cold start issue. I drive my carb'ed 2.7 year-round. It may be a touch more difficult to start in February than July, it is not major. Just make sure it is is setup right before the cold weather sets in and I think October could be a GREAT month for you.

[Dan Mc Intyre]

Ok, Hal - This is the sort of stuff I need to find out. So...just what happens when you start your car on a cool 45 degree morning? I envision pumping, sputtering, back firing, cranking and cranking. I drive my car in town quite often as it is kind of a daily driver. How long does it take your car to warm up and run smooth? I assume you're using Webers. What about this sputtering while hard cornering issue I've read about? What has been your experience with keeping them in adjustment and the jets clean?

I'd sure like to hear some details on your experience livng with carbs.

Thanks.

Dan

[Halm]

LOL... Sputtering and pumping happens in the heat of summer as well as in winter! Here is what I do: Turn on the ignition and let the system build some pressure while I put on my seat belt. Next I slowly pump the accelerator 5 times. Finally I hit the starter. It usually takes no more than 2 tries. As soon as it catches I pull up the hand throttle and let the carb’s “clear out”. As soon as they are running smooth, I lower the idle to 2K and off I go. All this takes no more than 2 minutes on a cold morning. Within 3 miles I release the hand throttle and things are pretty smooth until it is fully warmed up.

If you go with Webers, make sure they are freshly rebuilt by someone like Eurometrix or Bieker. You must start with a great set or it will be a pain to maintain them. Lots of people on the board can help setting them up, but I would recommend taking the car to a shop that knows carb’s and have them dyno tuned. This way you will know they are really right.

On the other hand, for a few more $$$ you can go with new PMO’s. I replaced my worn out –total POS- Webers with PMO’s and haven’t looked back. They are smoother, better mileage -22+ on the highway at 75- and a lot more power. First pull on the dyno they were up 20 over the Webers and finished up 27 over them. And Richard Parr is first rate to work with on them.

Hope this is what you were looking for.

[Grady Clay]

Ask Pelican rs911t what he thinks of his big bore 2.4T (2807 cc, 10.5:1 CR, S cams, heads, throttles, stacks, and pump calibration.)

Best,
Grady

[bigchillcar]

hi dan,
what you're interested in having, most all of us with 2.7 cis engines have already racked the collective brains on this board off many, many times. the consensus seems to be that your cis car, while it offers the benefits of improved fuel economy and drivaeability, there isn't much that can be done to it to improve performance sticking with this style induction..sketchers356 has already alluded to this when he mentioned the cam overlap issue. i don't think anyone realistically believes anymore that they can achieve your goal sticking with cis.

what i WOULD like someone to address would be pelican member tbitz' efi conversion. member flipper for one has recently done this mod on his 2.7, but good luck getting him to weigh in as he is currently enjoying a 'driving orgy' anyway, i wonder about the rs pistons, and performance cams with this efi conversion on a 2.7..anyone have any thoughts?
ryan

[TRE Cup]

here is a recipe for inexpensive build up IF you have some skills at doing the motor yourself:
get a set of JE higher compression p/cs' no more than 10.5 :1
get your ignition distributor recurved to RS specs
get a 78-79 CIS complete injection system (from a carb conversion?)
get a set of SSI's or headerswith twin outlet exhaust
get your cams reground to 964 spec or get the 964 cams with towers
port your heads to 38 mm intake- leave the exhaust alone
when setting up cam timing- go for as much advance in the spec range as possible
you will have a motor that puts out a true 200 hp coupled with everyday reliability. So in the end euro SC performance from a lighter car at low $$ investment. And it will look "stock" to the average Porsche guy

[Lukesportsman]

Dare I suggest at least thinking about MFI? It has cam selection limitations, but definitely better choices than CIS.....looks cooler and better throttle tip in.

I went with big bore 2.4 with RS cylinders and slightly bumped compression with milled heads. We setup the pump and ran E cams. This gave us a broad torque band and reasonable pull. I currently run it behind 8:31, but the 7:31 made it quicker out of the hole. I might be lighter than you with my no frills long hood, but it gets out of its own shadow. I have fast cars, and this isn't one of them, but it is a blast on a crooked road.

I'm still working on MB911's SS dual outlet muffler issues, but the fire on deceleration looks cool.

[bigchillcar]

luke,
i think many of us with 2.7 cis cars wish we had mfi, but what would the cost be to install it? the efi conversion of tbitz sells for around $1600 and might have lots of interesting programming options..still waiting to hear about what it might do with hotter cam/piston options..
ryan

[duffster]

I'm running a medium tweaked 2.7 with Timecerts, Racewear studs, "long rods", RS-spec P/Cs, C-6 Web Cams, Weber 46s, and an MSD box. It doesn't seem to have much problem scaring me. It has dyno'd 210 at the wheels. It can be a bit fussy if you're over 7000 feet, or when it hasn't been driven for a bit, but it'll put around on the idle circuits all day in townafter it's warmed up. Makes me wonder what an MFI 2.9 twin plug would do...

[Chuck Moreland]

Originally posted by TRE Cup
get a set of JE higher compression p/cs' no more than 10.5 :1
get your ignition distributor recurved to RS specs

What is the octane requirement?

[Fishcop]

Does anyone have the figures to give to the distributor people for a RS... a picture of the curve perhaps?

Ta

[bigchillcar]

can anybody with more experience weigh in? we all know that mfi and carbs are the induction 'way to go' for hot-rodding a 2.7, but where might the programmable efi option fit in the hierarchy? better than basic cis i suppose..?
ryan