Intake suggestions for 3.0 with Electromotive FI

[cowfly911]

I am a 911 newbie collecting parts for my future 911SC 3.0 engine rebuild. My plan is to install JE 98mm pistons & cylinders at 10:1 or 10.5:1 compression ratio (non-dual plug setup) , SSI headers/exchangers, and add a Electomoticve FI system. I currently have a 1983 3.0L engine with 964 cams and the Carrera chain tensioner in need of pistons and cylinders.

What would be the ideal intake manifold for this type of FI system? My first thought was to use the intake manifold from a 964. Anyone with history with this type of setup? My target is a streetable/track school 911 with about 250hp. Suggestions/opinions are welcomed.

Thanx in advance...

[Steve@Rennsport]

Hi:

If I might offer,....

1) Use Megasquirt EFI; its really much better than Electromotive.

2) If you are going to be above 9.7:1 CR on pump gas, you MUST use twin-ignition otherwise you will buy several sets of pistons until you do,...

3) A 964 plastic intake will work very nicely but you will need some adapters to mate the 3.6 3-bolt intake to your 2-bolt heads. I do have those.

4) You will either need the early ('78-'79) big port heads or have yours opened up and flowed otherwise the 3.6 intake is a total waste of money & time.


Hope this helps,

[cowfly911]

Originally Posted by Steve@Rennsport

Hi:

If I might offer,....

1) Use Megasquirt EFI; its really much better than Electromotive.

2) If you are going to be above 9.7:1 CR on pump gas, you MUST use twin-ignition otherwise you will buy several sets of pistons until you do,...

3) A 964 plastic intake will work very nicely but you will need some adapters to mate the 3.6 3-bolt intake to your 2-bolt heads. I do have those.

4) You will either need the early ('78-'79) big port heads or have yours opened up and flowed otherwise the 3.6 intake is a total waste of money & time.


Hope this helps,

Thanks for the feedback Steve! I am new at this and I would like to collect as much information as possible before diving in.

I will have to do some research on Megasquirt. I have a few friends that use Electromotive EFI on their SCCA cars and I thought I could use them as FI resources. They have been pleased with the Tec 3 system so far.

I do not want to goto the twin plug design, and according to Wayne's book I should stay under 10:1 compression ratio for the single plug ing. Is this correct? J&E sells a 98mm piston at 9.5:1 and 10.5:1 compression for the 3.0 engine. Should I consider the 9.5:1/ 98mm piston or stick with the 9.5:1/95mm piston?

Lastly, the intake I was considering is in the below pic (credit to the person I hijacked it from). I believe it is an alloy, not composite. Is this correct? I was only considering this for the aftermarket injection. Can the CIS intake manifold be used with the aftermarket injection systems?

Sorry for all of the newbie questions....

[Steve@Rennsport]

Originally Posted by cowfly911

I do not want to goto the twin plug design, and according to Wayne's book I should stay under 10:1 compression ratio for the single plug ing. Is this correct? J&E sells a 98mm piston at 9.5:1 and 10.5:1 compression for the 3.0 engine. Should I consider the 9.5:1/ 98mm piston or stick with the 9.5:1/95mm piston?

You may use whatever bore size you wish but stay at 9.5:1 for single-ignition running pump premium fuels and this is expecially critical in NC weather. Be conservative about timing, too.

Lastly, the intake I was considering is in the below pic (credit to the person I hijacked it from). I believe it is an alloy, not composite. Is this correct? I was only considering this for the aftermarket injection. Can the CIS intake manifold be used with the aftermarket injection systems?

That intake will work, but its not anywhere near as good as the later, plastic version. Its heavy and doesn't flow as well. The CIS intake is an abomination for someone looking for power,...

[CindyDuck]

I have a 3.2L on my 79 SC with Megasquirt. I used the Bitz raceing setup.
I love it.
Mike

[cowfly911]

Originally Posted by CindyDuck

I have a 3.2L on my 79 SC with Megasquirt. I used the Bitz raceing setup.
I love it.
Mike

Is your 3.2 a 3.0 with the 98mm pistons or a 3.2 Carrera engine? What is the Bitz racing setup?

Thanks for the help, you guys are great...

[euro911sc]

A good thread for you:

EFI Kicks A$$ - the ST goes electric


-michael

[JohnJL]

Steve knows his stuff and I am not in any position to debate the Alu vs Plastic 3.2 intakes but I have the former and like it. Bonus is I plan on reusing it for the supercharger build.

John

[cowfly911]

Originally Posted by Steve@Rennsport

You may use whatever bore size you wish but stay at 9.5:1 for single-ignition running pump premium fuels and this is expecially critical in NC weather. Be conservative about timing, too.

That intake will work, but its not anywhere near as good as the later, plastic version. Its heavy and doesn't flow as well. The CIS intake is an abomination for someone looking for power,...

Thanks Steve! So I now know I need to stay with the 9.5:1 pistons 98mm diameter (bigger is better) and the plastic intake from a 964 (3.0L engines require 3 stud adaptors for the intake).

I need to make a Christmas list...

[cowfly911]

Originally Posted by euro911sc

A good thread for you:

EFI Kicks A$$ - the ST goes electric


-michael

Thanks for the link! It looked very interesting with eye candy of fuel maps...

[CindyDuck]

let me clarify,
I have a 79 3.0 stock P&Cs, 3.2 intake and Bitz EFI.
Do a search for Bitz mega squirt, great system.
Mike

[sjf911]

Twin plugging with an EFI setup is not that big of a deal and does allow you to be more aggressive with the setup. I'll be interested in seeing your experience if you go with the plastic intake. I may go that direction in a couple of years when I go for a 3.5 build.

[munsonbw]

Originally Posted by Steve@Rennsport

Hi:

2) If you are going to be above 9.7:1 CR on pump gas, you MUST use twin-ignition otherwise you will buy several sets of pistons until you do,...

What about the Euro SC's with 9.8:1 CR? Should I be worried? I am pretty versed in engines and their noises and have never heard any knocking or pinging. Additionally, I had the motor appart a month ago and everything looked fine... although I didn't take the pistons out of their bores.

Thanks,
Ben

[Steve@Rennsport]

Ben:

The first thing I'd tell is that if you rely on your ears to tell you whether a 911 engine is detonating or not will result in buying many expensive parts. They are not very good as "knock sensors" in air-cooled engines.

Europe has 98 RON fuels (similar to our 94 R+M/2) and its also not as hot as Alabama in the summer.

You would not believe how many times we have disassembled an engine to watch the rings fall on the floor as the cylinders were removed. The owners never heard a thing,..........

Mahle's advertised CR's are always lower than actual measured values and thats why many folks appear to get away with things.

[safe]

Originally Posted by Steve @ Rennsport Systems

Ben:

Europe has 98 RON fuels (similar to our 94 R+M/2) and its also not as hot as Alabama in the summer.

Actually we even have 99 RON, at least in some countries, but that's only been around for couple of years.

The stock euro 3.2 runs 10.3:1 compression ratio with single plug.
Would a 3.0 with the same compression be different?

[munsonbw]

Thanks for the info Steve. I guess I just have to hope everything is OK. I always run 92-93 octane as it is readily available everywhere I have lived.

What are your thoughts about using extra fuel to cool things down? Does this work effectively? If so, care to make a statement about WOT air fuel ratios from say 4k up?

[Eagledriver]

As long as you are conservative on the ignition advance and don't run lean Euro piston SC's are ok on 91 or greater pump gas. We have about 5 of these engines in our spec class and they haven't had a problem even racing.

-Andy

[Steve@Rennsport]

Originally Posted by Eagledriver

As long as you are conservative on the ignition advance and don't run lean Euro piston SC's are ok on 91 or greater pump gas. We have about 5 of these engines in our spec class and they haven't had a problem even racing.

-Andy

Andy is right; be conservative about ignition timing and get as much fuel into the engine as is practically possible without making it misfire. CIS engines tend to become rather lean above 4500-5000 RPM making them difficult to "fuel-cool".

Mahle's & Porsche's advertised CR's are always higher than actual measured values and thats why they do OK on 92-93 octane gas. If one tweaks the engine to achieve specified compression, one will need better gas unless the timing is reduced which affects low & mid-range torque.

[euro911sc]

hehehe yeah... well here is what happens when your ROW SC gets some bad gas and I'm not talking about the smelly kind

And the pieces came a tumblen' down...

Its been recommended to stick around ~9.5:1 to add some safety factor against the above thread... Even so, I'm simply putting it all back the way it came from the factory I suspect that the actual compression is less than 9.8:1 I'll be measuring that in the next week or so...

Can you run a higher compression with EFI than with CIS?

Best regards,

Michael

[munsonbw]

Euro911SC,
Your pics are what had me scared about my car!

Eagledriver, Steve,

I was hoping you would say that extra fuel would help things... that was my understanding about internal combustion engines, generally speaking. As far as timing, right now I am at 33 degrees total advance, which from memory seems to be full in by 4k. Does this sound right our should I back out a degree or two? I am certainly not worried about leaving a pony or two on the table for the sake of engine life. I am planning to hook up the LM-1 and take some AFR measurements this month. Any clue for a target AFR?

Thanks guys.

cowfly911, sorry for hijacking your thread, hopefully there is some useful information in my questions for your project. I will add a comment for your specific project. I am running a Megasquirt on my Lotus clone and I think it is great. The support forums are fantastic and it really is pretty easy to set up if you understand what is going on. The manual goes into EFI theory, and I think that helps the user understand the goal better, not just what steps to do next. As note of comparison, my dad has the older Holley multi-port EFI system and it is not very user friendly. Lots of variables are hard coded into the program and the documentation is pathetic... I have seen more in depth manual for hammers. My point, whatever control system you choose, research it thoroughly so you know what you are getting into. I hate to question other's abilities or knowledge, but one user here was badmouthing the Megasquirt system and how awful it was to set up. In reality, he didn't really understand what he was using, for his abilities a plug-and-play would have been a better route. I think he later scrapped it and went with the Electromotive since he had a local dist. Understand your abilities and make your choice.