EFI conversion

[drmatera]

ok guys, i'm starting my EFI project today. The engine is coming out this afternoon and i've started the process of welding 2 stock intercoolers together. (pics to follow)

Here is a run down of my plans and I have a few "while i'm there" questions for you guys that have done it.

GAME PLAN:
Megasquirt MS2 / EDIS 6

Replacing stock phenolic spacer/injector holders with custom machined phenolic spacers designed to accept standard Bosch style injectors

Building custom fuel rails and fuel system

installing new clutch

ADDITIONS:
Should I twin plug the heads? in other words is the power gained worth the expense?

Might as well put cams in - which cams? (99% street car, stock engine)

Shave 1mm off heads for 8:1 compression

Any insight from those that have done this would be greatly appreciated. I'm looking for a 450-500hp street engine (turbo upgrade later to meet power goal)

[beepbeep]

My 5c:

- don't shave the heads, low C/R is nice once you start boosting more than usual. Just machine them flat to get rid of uneven surface.
- Ditch the OEM intake and use Carrera plenum. It will need extra rework of heads (or adapter) in order to seal CIS head to EFI plenum but on the other hand, you can re-use Carrera rails. Injector holes are plug & play and it flows better as well.
- Twin-plug the heads if you already have them off. Even if you don't plan to use twin-plug yet. you can leave the lower plugs in the head and then just add EDIS-6 when you want.

[911st]

Many of us will have different views on much of this.

C/R.
This depends on your goals. It is almost hard to burn high octane gas at such low compression and make any power without compression pre boost.

Thus, if you want to improve drivability, add compression. If going for HP bragging rights, keep the stock compression. SC cams actually lower effective compression in about the same amount as shaving the heads raises CR.

It is unlikely shaving the heads will get you even close to 7.5 /1 as the factory seemed to over rate there compression numbers. J&E replacement pistons are a better way to get there.

Twin plug: IMO, this is a big plus with CIS Turbo running low compression. With CIS comes less than perfect AFR's and twin-plug's help insure preboost combustion. It also can add a little efficiency, response, and TQ in the preboost part of the power band.

However, once under boost the need for twin-plug is reduced. IMO with boost we have a very volatile situation anyway and single plugs are more that sufficient to make HP. Further a 930 run a much flater piston keeping the composition chamber much more open an greatly reducing the problem that comes with a normally aspirated motor that has to bend the combustion around the top of a domed piston. So, twin plugging is not anywhere as much a benefit on a Turbo under boost so long as you manage your ignition advance and AFR's well which is what EFI is good at.

In suport of my opinion, if you look at the timing advance for twin plug motors and turbo motors the max WOT advance is mostly the same at about -25 deg to reach peak combustion pressures at the best time.

RUF nor Porsche with the 993TT saw the need for twin plugging in the 450-550hp range.

Thus, with EFI's ability to better control ignition and AFR's the benefit of twin plug needs to be weighed against the cost. I suspect there are better places to put that money like a more respected EFI unit, more efficient inter-cooler, or the help of a good tuner to set up the injection tables, for example.

Still if doing a best of the best motor it is an option and dose have some advantages.

[ZLP]

Originally Posted by beepbeep

My 5c:

- don't shave the heads, low C/R is nice once you start boosting more than usual. Just machine them flat to get rid of uneven surface.
- Ditch the OEM intake and use Carrera plenum. It will need extra rework of heads (or adapter) in order to seal CIS head to EFI plenum but on the other hand, you can re-use Carrera rails. Injector holes are plug & play and it flows better as well.
- Twin-plug the heads if you already have them off. Even if you don't plan to use twin-plug yet. you can leave the lower plugs in the head and then just add EDIS-6 when you want.

Hey Goran, have you guys ever tried a carrera intake with stock 930 heads w/o porting?

[drmatera]

ZLP- the difference in port sizes between the carrera and 930 motor is substantial, creating a "ledge" that would horribly impact air flow.

911st- thanks for your insight. I appreciate your explination of twin plug advantages and may just hold off on doing that right now. I did not choose the megasquirt based on price but more based on my direct experience using it. For the run of the mill street car under 1000hp there are zero advantages to using the high cost alternatives. That statement is based on actual experience, not opinion. The megasquirt will handle my fueling needs, spark advance, boost control and methanol injection system perfectly well for what i'm doing.

beepbeep- Using the Carrera manifold has crossed my mind, but since adapters will have to be made to fit the intake it really doesn't cut down on fitment issues and it will also negate the use of a stock style intercooler

[Ken911]

Originally Posted by drmatera

ZLP- the difference in port sizes between the carrera and 930 motor is substantial, creating a "ledge" that would horribly impact air flow.

911st- thanks for your insight. I appreciate your explination of twin plug advantages and may just hold off on doing that right now. I did not choose the megasquirt based on price but more based on my direct experience using it. For the run of the mill street car under 1000hp there are zero advantages to using the high cost alternatives. That statement is based on actual experience, not opinion. The megasquirt will handle my fueling needs, spark advance, boost control and methanol injection system perfectly well for what i'm doing.

beepbeep- Using the Carrera manifold has crossed my mind, but since adapters will have to be made to fit the intake it really doesn't cut down on fitment issues and it will also negate the use of a stock style intercooler

You have to change the intake studs any way and you are going to drill them for twin plugs just go ahead and port match them to the 3.2 intake

[jonesb930]

There was a guy out west that was taking the Carrera intake and rotating the TB section to line up with a stock IC on the 930. With his modification you could swap the intakes and add a blow off valve and be good to go. I did a similar modification to mine just to eliminate having the air do a 120 degree turn out of the IC. You would still need to port match the heads though. Also keep in mind that Twin plugging adds to the complexity of the converion. You will either need to do a wasted spark coil on plug setup or a dizzy swap for a 964 one. Of course if you have money to burn you could pick up this one here on the forum FS Marelli Twin Plug RSR Distributor



This is the direction I am going at the moment:
Carrera Intake
70mm Throttle Body
GT2 EVO cams
3.2 P&C (7.5CR) -it was a 3.0L turbo motor
Port Matched and Ported heads
Twin Plugged (They were already at the shop and at the time I had the cash)
964 Oil Pump
Carrillo Rods
Raceware Hardware
Boat Tailed case
Knife Edged Crank, Micro polished and cross drilled
Shuffle Pined case
Over sized Piston Oil Squirters
MOTEC M600 ECU
Pair of K16s
Everything balanced to with a .1 of a gram

Still need to buy/fabricate
Headers
Intercooler

[JFairman]

You have to port match the 930 heads to the Carrera runners.
930 intake ports are 32mm diameter at the intake flange and first inch or so going inwards and the Carrera intake runner is 40mm ID at the flange.

It just takes time with a die grinder and air compressor...
..the neighbors will love the sound of your air compressor and die grinder wailing away for hours on end into the night while you are port matching and smoothing out your ports and making a nice pile of aluminum chips on the ground.

Pelican sells nice 10mm thick 40mm heat insulator blocks that come with 12 intake gaskets and 12 stainless steel 8mm studs for around $45. They are made by PMO and are not in the pelican catalog, you have to ask Glen for them.

************************************************** ************************************************** ************************************************** ********************
Just noticed another 930 guy in northern Palm Beach County, Fl... Bill Jones, in Jupiter.

We should all get together with our cars someday. Seems there's around a dozen or so of us in a 60 mile radius around West Palm Beach..

[jonesb930]

Sorry, JFairman is absolutely correct! I forgot to mention that (though it was stated by an earlier poster) but forgot. I did have mine matched and it is a must! And thanks for the tip on the studs and insulators.

Bill

[beepbeep]

Originally Posted by ZLP

Hey Goran, have you guys ever tried a carrera intake with stock 930 heads w/o porting?

It won't be good. But OEM 930 intake is so lousy that I would gladly port the heads or change to Carrera heads than keep the stock stuff. Also, Carrera intake has everything else done (rails, injector bungs etc.)

Pictures are courtesy of various posters here, cannot remember who's they are:

[jonesb930]

Here are some additional pictures of my heads and intake setup:

[911st]

Did not mean to put down the MS system. I have looked into it and it is a very sophisticated system with a lot of followers. My reasoning is one of the most important resources in a conversion is having access to a proven tuner that can fast track set up on a dyno without blowing a motor. The other is it may limit buyers with a resale.

I like the Carrera intake manifold. 32mm ports are quite a restriction anyway, the Carrera flows much better, and one could use its stock fuel supplies to reduce fabrication work. On top of that, if you do not already have in upgraded inter-cooler, it is less expensive to have one fabricated to work with the Carrera manifold. Might even make sense to sell an good aftermarket CIS IC and use the cash to have a custom fab'd to work with the Carrera manfold.

[JFairman]

Flipping around the Carrera intake like that looks like it would also leave you more room for an AC compressor.

Little details like that are very important if you ever want to have willing female passengers in southern Florida.

[jonesb930]

I already have a wife, not looking for another :-) and the wife doesn't like me driving fast. One is expensive enough...

[Ag02M5]

I don't suppose there is a reasonable way to make the 965 intercooler work with the 3.2 setup?

[911st]

Yes, flip the center section as above or modify the end tank on the IC.

[turbo nut]

Use the carrera manifold. Why not twin plug can't hurt is very easy to do with edis have done a few now.

[mppickett]

I also like twin plugging. You run less spark advance since the flame propagates more rapidly. It is very easy and cheap with Megasquirt and EDIS 6 (see Megasquirt setup for 930 and dual plug EDIS).

[DonE]

Based on personal experience, do not shave the heads for compression. You will reduce the distance between the cams and the crank shaft, thereby adding slack to the cam chain. You will then need to buy an oversized cam chain tensioner pulley to take out the slack (which is not a bad setup - mine is set up this way - but there are better options). However, 8.0:1 CR makes a 4 speed car a joy to drive in city traffic compared to stock. Off boost acceleration and behavior is great.

Also, twin plug the heads while they're out. The combustion chambers are pretty big, and when you introduce forced induction (14 psi of swirling air) into an effective compression ratio of 12:1 or greater, you'll either blow out the flame (yep, I'm serious) or the spark might not be hot enough to light it off completely. You didn't mention what type of ignition system you will use. If its wasted spark, you will definitely need twin spark. If its CDI, you should have it. Remember, you do not add twin spark for HP, you add it for combustion efficiency and spark control. In a violent environment like the inside of a turbo charged combustion chamber (air cooled I might add), you ideally want a very hot and precise spark. Added benefits like smooth idle and throttle response really point to twin plug and a good ignition system.

Good luck with your build.

[jonesb930]

I was actually planning on using a 965 IC before I decided to go with twin turbos. It lined up perfect with my intake. It has since been sold. The Carrera intake is a really nice piece for an EFI conversion. Try to get one complete with the fuel rails and throttle body if you can.