1977 2.7 Engine Rebuild Enhanced Parts Suggestions?

[rwest]

Hi,

Currently tearing down my 2.7 and will need to rebuild heads, grind cams and probably replace pistons and cylinders.

I have Bitz EFI and a MSD box with points ignition.

I want a car that is fun on streets and touring, no racing. Car will spend most of its time in the 2,000 to 4,000rpm range I would think.

What would you suggest for cam grind and piston type?

Thanks,
Rutager

[Trackrash]

Will this motor need to pass smog checks?

Will you be keeping the CIS injection?

Will you need to replace your cylinders?

In a perfect world you could put in larger pistons and cylinders with higher compression, something like E or S cams, run Weber carbs, and a backdated exhaust.

The next level would be dual plugs and ITBs or MFI.

[rwest]

Hi Gordon,

CIS has been replaced with the Bitz EFI already.

I’m trying to keep on a budget, but will replace parts if needed. All my reading seems to lead me to believe that a 2.7 can’t be made bigger easily or cheaply, so my very uneducated thoughts are that piston shape and cam profile might be the only variables?

I do have the backdated exhaust and don’t have smog requirements to meet.

Are 964 cams a good choice?

Thanks,
Rutager

[Matt Monson]

2-4K rpm? Why change anything then. They don’t even wake up below 3k. You do mods for power and performance and the biggest gains are in the 4-6k range. There’s plenty you can do but it sounds like what you really need to do is drive your car a little harder. They like that.

[Trackrash]

964 cams are for smog motors. You want something like DC 30 or DC 35. Once you decide on displacement and compression get in touch with John "Camgrinder" Dougherty.

If your cylinders are Mahle nikasil and in spec, you could get something like JE pistons in 9.5 -1 CR. If your cylinders can't be used as is you could get them bored and replated and use JE or other pistons to match.

I know a guy who has a 2,9L on a 7R case. He has webers, 9.5 -1 CR and it screams.

[Evans, Marv]

I did a '77 2.7S for my car almost 15 years ago. My car is a '69. If you are going to be using it for the street, I'd suggest E cams, if those work well with the Bitz EFI. I built my engine to last - at least what I thought would help it last a long time and used the 2.7L engine because I already had it setting around. I've got Webers on it, a crane ignition with an optical pickup. Inside I went for Nikasils w/ 9.5 J&E's. Additionally I had a bunch of things dry film lubricated: bearings, piston skirts, wrist pins, oil pump, & who knows what else. I had the piston tops, combustion chambers, exhaust ports, & valve faces thermal barrier coated. I also went with some other things like ARP rod bolts & a rebalance. I can't remember exactly all I did/had done, but I'd at least go for the Nikasils, J&E's, & E cams if I were you.

[rwest]

Originally Posted by Matt Monson

2-4K rpm? Why change anything then. They don’t even wake up below 3k. You do mods for power and performance and the biggest gains are in the 4-6k range. There’s plenty you can do but it sounds like what you really need to do is drive your car a little harder. They like that.

Hi Matt,

I just didn’t want to sacrifice low end for top since since I wouldn’t be taking it on the track. Nice to have good acceleration and passing power on the street and in the curves.

I have several bad exhaust valves and at least one beat head/scratched cylinder from a foreign object, so have to do something. Sounds like I might just be fine with a stock rebuild for my needs?

Thanks,
Rutager

[rwest]

Originally Posted by Trackrash

964 cams are for smog motors. You want something like DC 30 or DC 35. Once you decide on displacement and compression get in touch with John "Camgrinder" Dougherty.

If your cylinders are Mahle nikasil and in spec, you could get something like JE pistons in 9.5 -1 CR. If your cylinders can't be used as is you could get them bored and replated and use JE or other pistons to match.

I know a guy who has a 2,9L on a 7R case. He has webers, 9.5 -1 CR and it screams.

Hi Track,

I’m not going to let you get near my credit card, that would be dangerous!

My cylinders say Mahle and the inside walls are magnetic- does that mean Nikasil? Who do you recommend for reconditioning cylinders? 9.5 still single plug and regular gas- I use ethanol free premium around town, but on road trips sometimes good gas is harder to find.

Thanks

[rwest]

Originally Posted by Evans, Marv

I did a '77 2.7S for my car almost 15 years ago. My car is a '69. If you are going to be using it for the street, I'd suggest E cams, if those work well with the Bitz EFI. I built my engine to last - at least what I thought would help it last a long time and used the 2.7L engine because I already had it setting around. I've got Webers on it, a crane ignition with an optical pickup. Inside I went for Nikasils w/ 9.5 J&E's. Additionally I had a bunch of things dry film lubricated: bearings, piston skirts, wrist pins, oil pump, & who knows what else. I had the piston tops, combustion chambers, exhaust ports, & valve faces thermal barrier coated. I also went with some other things like ARP rod bolts & a rebalance. I can't remember exactly all I did/had done, but I'd at least go for the Nikasils, J&E's, & E cams if I were you.

Marv,

Track is recommending the 9.5s as well, how do you like them? Sounds like you have a great motor. Not sure about e cams, I do know that the Bitz needs decent vacuum to work properly.

Thanks,
Rutager

[Matt Monson]

Originally Posted by rwest

Hi Matt,

I just didn’t want to sacrifice low end for top since since I wouldn’t be taking it on the track. Nice to have good acceleration and passing power on the street and in the curves.

I have several bad exhaust valves and at least one beat head/scratched cylinder from a foreign object, so have to do something. Sounds like I might just be fine with a stock rebuild for my needs?

Thanks,
Rutager

Since you have EFI already I would rebuild it to RS spec, but maybe go with a mod-S cam instead of full S spec. That has a nice broad powerband and you will pick up well over 50hp.

[rwest]

Originally Posted by Matt Monson

Since you have EFI already I would rebuild it to RS spec, but maybe go with a mod-S cam instead of full S spec. That has a nice broad powerband and you will pick up well over 50hp.

So you’re saying I won’t be able to drive it like a little old lady then?

Does the RS piston have a different shape that helps gain HP along with the cam grind?

Recommend any shops to refurb my cylinders and match them up with new pistons, or is it a buy the whole new set sort of deal?

Thanks

[Trackrash]

Sorry, I don't have any experience with the Bitz setup. So will defer to others for specifics.

There are a couple of choices for refurbishing your cylinders. If 5 of your cylinders are in spec, you might want to find a good used replacement. This is what I did with my current SC motor. One of my cylinders was defective.... BTW, I have the tools to measure my stuff and a good friend is an old Porsche machinist as a back up.

Search this forum and you can get opinions on who to use for your cylinders.

As far as $ goes, that is a subject for another thread. But look at it this way. If you invest correctly it will pay off in the end.

FWIW, that machinists friend of mine's wife has a '74 Targa with an all stock motor. It runs great as is.

[zedsn]

My car had a 2.7 RS spec motor in it when I bought it and Ollies did all the machine work and ARP head studs were used along with a 930 oil pump. The cams were sent out to Web for a hot street grind. This car was fun to drive and I just sold the car last week and still have sellers remorse.

[roblav]

Recommend 9.5:1 compression on S or Solex cams. Go slightly less compression on E cams.

A bigger cam allows for higher compression ratio because of valve overlap.

[Matt Monson]

Originally Posted by rwest

So you’re saying I won’t be able to drive it like a little old lady then?

Does the RS piston have a different shape that helps gain HP along with the cam grind?

Recommend any shops to refurb my cylinders and match them up with new pistons, or is it a buy the whole new set sort of deal?

Thanks

You will lose a little low end. Here's some analysis from a member's (analog man) personal webpage:
Analog Mike's 911 engine page

You will notice the RS spec engine gains everywhere over a 2.7 CIS. It's not some straight trade where you lose low end to gain up top. Make the whole engine more efficient and it will make more power everywhere.

The RS is MFI, so does have a more traditional dome design. You can run something like an S cams if you want to. You might also look at Solex or mod-solex grind for the kind of driver you want.

I would recommend Engine Builders Supply. They can recondition your cylinders for you. They can go through the heads too if you like. They sell JE pistons and you can get them around 8.5 like an RS if you want, or you could go higher into the low 9s like some others have suggested.

[rwest]

Originally Posted by Matt Monson

You will lose a little low end. Here's some analysis from a member's (analog man) personal webpage:
Analog Mike's 911 engine page

You will notice the RS spec engine gains everywhere over a 2.7 CIS. It's not some straight trade where you lose low end to gain up top. Make the whole engine more efficient and it will make more power everywhere.

The RS is MFI, so does have a more traditional dome design. You can run something like an S cams if you want to. You might also look at Solex or mod-solex grind for the kind of driver you want.

I would recommend Engine Builders Supply. They can recondition your cylinders for you. They can go through the heads too if you like. They sell JE pistons and you can get them around 8.5 like an RS if you want, or you could go higher into the low 9s like some others have suggested.

Great link Matt, thanks.

I do like the low end of the CIS chart, but dang the RS just keeps going!

Wayne recommends the 964 grind with the RS pistons in the rebuilding book; any thoughts on that setup?

[roblav]

I don't understand the difficulty of the decision! Someone already mentioned that 964 cams are for smog engines.

I built an 2.7 RS type with Webers in 1994 for a 1972 911, and it was my daily driver for a few years. It was the best driving combo Porsche air cooled engine / chassis I ever had (and I had many). The only negative I can think of was the fuel mileage... around 17 on the highway comes to mind. But I drove that thing under "full enjoyment". ITBs and EFI will likely get you much better fuel economy, and the oil won't thin out so rapidly without the Weber acceleration plungers squirting raw fuel into the cylinders!

Ahhh.... the good old days when decision-making seemed to be so much easier!

[rwest]

Originally Posted by roblav

I don't understand the difficulty of the decision! Someone already mentioned that 964 cams are for smog engines.

I built an 2.7 RS type with Webers in 1994 for a 1972 911, and it was my daily driver for a few years. It was the best driving combo Porsche air cooled engine / chassis I ever had (and I had many). The only negative I can think of was the fuel mileage... around 17 on the highway comes to mind. But I drove that thing under "full enjoyment". ITBs and EFI will likely get you much better fuel economy, and the oil won't thin out so rapidly without the Weber acceleration plungers squirting raw fuel into the cylinders!

Ahhh.... the good old days when decision-making seemed to be so much easier!

Hi Rob,

My memory was off, the recommendation was for “S” cams for the RS build. I hear so much about the 964 cams that I needed to ask. I’ll check with Dougherty Cams to see what grind he has that isn’t top heavy- like Matt said a modified “S”.

No ITBs on the car though, the Bitz EFI uses the CIS throttle body and intake. I do have to make sure the cams will work with the Bitz as it uses vacuum for throttle position.

Thanks,
Rutager

[Matt Monson]

The idea of a “cis friendly” cam is because of piston dome design. The 964 is the most aggressive you can go with a cis piston.

Once you change the pistons to something more traditional your cam choice is unhindered. The cis top parts don’t matter.

[roblav]

Ahhh.... thanks for clarifying the Blitz thing and CIS / K-Jetronic. That changes things.. and is out of my knowledge zone.

I built some ITB's out of Suzuki GSX-R 750 throttle bodies for a 911 a few years ago. They're relatively cheap and effective... in case you ever consider going that route. CIS is something I avoided. Good luck and take care. RL