Ferrari Forums banner

1 - 18 of 18 Posts
G

·
Discussion Starter #1
I know...I've got to a scr

I know...I've got to a screw loose to even consider this path, but I still have to ask.

Convert my carbed BB to sequential FI using a Motec system...Thoughts??

Regards,
David
 
G

·
Discussion Starter #2
Hi David, it's pobably wor

Hi David, it's pobably worth 40-50 more HP. The 312PB & T's ran Slide Valve Injection (also P4's) for up to about approx. 550 HP.

Two main reasons the injection can increase HP = Flow & Flow {
}

With nothing in the Bodies/Stacks/Runners to interfere, air flow and velocity is dramatically increased, while at the same time fuel flow can be increased to accomodate the increased air flow, the result is considerably more power. A side benifit of electronics over mechanical is metering ability to a wider range of use conditions and throttle settings.

Motec conversions are expensive but worth it imo.

Regards, JRV
 
G

·
Discussion Starter #3
Where can I find some info. ab

Where can I find some info. about the Motec conversion? Just like to see it, I don't have a boxer....yet..
 
G

·
Discussion Starter #4
Sean,
This type of conversion


Sean,
This type of conversion could really be done on any type of car, or engine. Make no mistake, big money, big time commitment...and big headaches to do from scratch on a carbed car. But, in the end, very rewarding from the little I've learned thus far. Hey, who could complain about picking up more HP and driveablitiy, both at the same time?

Here are a couple of interesting links on the subject:

www.motec.com
http://www.twminduction.com//Home/Home-FR.html

Regards,
David
 
G

·
Discussion Starter #5
Thanks Dave.

What advantage


Thanks Dave.

What advantage could be gained form using this type of system on a 308 HP wise? I understand the other advantages?

Would it be a good replacement system, when combined with ECU and a direct spark ignition system on an early FI 308's?

Would it even be worth it? I've seen some ECU systems from $2-$3k + the cost of the FI kit..sure seems like it could add up to big $$ in a hurry.

Is it even worth it?
 
G

·
Discussion Starter #6
Sean,
The biggest advantage o


Sean,
The biggest advantage of using a Motec type system over the CIS system, as used on the 308s...is tuneability. While it would be a great repalce for virtually any type of induction system, the cost are substantial and could run into the $10,000 range if you're starting from scratch...

Is it worth it?
Probably not for a street application...

Regards,
David
 
G

·
Discussion Starter #7
The Bosch K-Jetronic Constant

The Bosch K-Jetronic Constant Injection System (CIS) mechanical Fuel injection is a brilliant piece of kit for when it was designed and what it was designed to do (primarily meet ever tightening emmissions control requirements in the 70s and 80s). There are three major impediments to the Kjet system from a performance standpoint: high system resistance to airflow, response and limiting of camshaft profiles as the flow metering plate is sensitive to pulsations. However, Kjet is excellent at delivering stoichiomentric proportions at steady flows and is reliable. The resistance to flow problem can be overcome in spectacular fashion by forced induction, exemplified by the late 70s Porsche Turbo Carrera.

EFI serves to alleviate all of those concerns, especially if seperate butterfly runners are used to allow better flow. David makes a good point that it is not inexpensive and is a bit complicated.

Well, except for fuel efficiency and emmisions, Weber carbs also are a better performance choice over the Kjet. If you look grossly at the hp loss when 308s went from Webers to Kjet, you will get the idea. Many older Porsche 911 owners with Kjet use the popular PMO conversion to carbs with amazing results, especially in engine response, for about $3500. This allows better airflow, response and tunbility.

And, fwiw, that is about what it's costing me to convert my older Kjet Mondial to Webers. While we are still fine tuning the jetting, the experience parallels the Porsche reviews: not sure of the magnitude of the definite hp increase, but the change in response and personality is incredible. Then again, I like raw edginess. For me this was cost effective and a lot of fun to do. I've lots more details if anyone interested.

The Motec kinda does it all, and adds a lot more efficiency, and the tuning is done electronically with more control of variables as opposed to swapping jets. The Webers are a more cost efficient way to performance over the CIS.

With Ferraris, however, I've noticed, the most 'cost effective' way to get major performance increases is to buy the next newer model.

In any event, look at how you use your car and have fun.
best
rt
 
G

·
Discussion Starter #8
Russ,
Thanks for spelling thi


Russ,
Thanks for spelling this out, in detail. I particularly enjoyed your explanation, specially the line "Well, except for fuel efficiency and emmisions, Weber carbs also are a better performance choice over the Kjet..."

The Webers on the BB do excel in several categories:

Fuel economy-Not!
Emmisions-Not!
Fun factor-Yes!

Enjoy,

David
 
G

·
Discussion Starter #9
David
Couldn't agree more


David
Couldn't agree more. I think a carb BB's have IMMENSE personality and raw edginess - way fun.

And like the hokey pokey, that's what it's all about.

best
rt
soon to be owner of Iridium plugs
 
G

·
Discussion Starter #10
>>And like the hokey p

>>And like the hokey pokey, that's what it's all about<,

ha Ha Ha Ha ...you're dating yourself...{
}
 
G

·
Discussion Starter #11
So my next question is would i

So my next question is would it be possible to make improvement to the K-jet either with better injectors, or a better control/chip so to speak to add some power to the early FI cars?

Would that even be worth it?

What year/model Mondial do you have and what kind of power increase are you expecting to see? Sounds like it would be better to simply remove the emmissions controls on the FI cars and install Webers (will the 79 intake manifold fit onto a FI car?)
 
G

·
Discussion Starter #12
Sean
Great questions.
The on


Sean
Great questions.
The only specific Kjet mod out there now I know of is the Lenz system from Germany. It replaces the ecu and combines the ignition/injection ECUs (they are essentially seperate systems stock). I want to say that it costs about $4K but that was some years ago. This system is actually endorsed by Ferrari Deutschland and dealers install it - or at least they did when I was there. You can check it out yourself:
http://www.lenzmotorentechnikusa.com
To me, anything is worth it if it gets rid of the Marelli ignition, but I have extreme opinions about that so temper my comments.

There have been some other claims at increasing K-jetted cars from Nick's Forza Ferrari, but involve porting and polishing heads and all - that's all I know about that. They also sell Electromotive ignitions claiming a performance increase as well. I really cannot comment on them much.

And to be complete, Norwood offers a turbo kit for K-jetted cars, which are very compatable as we spoke with forced induction. There are also some guys doing supercharging, but each installation is unique.

A 2v manifold will not fit a 4v car. Not sure about a 2v carb manifold on a 2v FI, but probably will work. My 88 3.2 uses a set of cast manifolds from Modena engineering in Austrailia, 4 X 40DCNF carbs and a stock 308 airbox taking fresh air from the side scoop. Most folks I have talked to in Austrailia (Frank Capo) and some engineers in America (Carobu, among others) most estimate about a 30-40 hp gain with a better exhaust (I have a tubi) to take advantage of the increased flow (It is a system). It will feel like more because of more instant response as there is a sl. delay in Kjet response time. I am also looking at a simple Marelli ($238) distributor to allow easy timing and advance adjustments as well as to address my terrible experience with Marelli reliability (source of my extreme opinions). My own calculations put me at about 290-300 hp as well as I am shooting for 90 - 95 hp/liter which should be do-able on a 4valve engine. One option that opens up later is that I can put better cams in it which should easily put me close to the 100 hp/liter range.
While all of these numbers sound nice, my car is a street car and the improved response with mild power boost is all I need And did I mention the SOUND? Wow. Like everyone says, the carb's cars really sound better than the Kjet.

Anyway, enough of me rabbiting on. Here are a couple of pics from the conversion before the distributor replacement. Hope this helps.
best
rt

 
G

·
Discussion Starter #13
If anyone's interested, I

If anyone's interested, I put motec on my old BB512. I pulled the insides out of the carbs and made some tapered venturis and installed the injectors in the inlet manifold just under the carbs. The car sounded exactly the same as before (awesome) and looked like a carb car, but the difference with HP, torque, smoothness, starting etc was quite astounding.
 
G

·
Discussion Starter #14
I dont know what kind of a dif

I dont know what kind of a difference it makes on a carbed car, but i changed my 87 FI Countach to an electromotive electronic fuel injection and distributorless ignition, and the power gains were incredible. Absolutely night and day.
 
G

·
Discussion Starter #15
Hi Peter,

I'd be very i


Hi Peter,

I'd be very interested in hearing all the details about the Motec set-up on your BB...Thanks.

Regards,
David
 
G

·
Discussion Starter #16
David, what in particular woul

David, what in particular would you like to know? I've mentioned how it was done. I was really happy with being able to keep the sound and look of the engine/intake yet have the benefits of FI. Ask away, and I'll do my best to answer.
 
G

·
Discussion Starter #17
Peter,

On the motec what is


Peter,

On the motec what is you finally spend to get it all sorted out? Are you a computer genius? Where you able get the baseline Motec to work pretty well? How did you tune it and how difficult was it to tune all the street parameters like extra idle speed when the A/c flipped on etc? Ferrari does a good job in compromises between the street and the track. Were you able to easily map all the compromises needed to have a very driveable car with good power?
 
G

·
Discussion Starter #18
Bob, I'm in Australia, so

Bob, I'm in Australia, so i'm sure the prices would have no validity. Suffice to say, it was thousands (5-6 i think). I tuned it on the dyno, which, as far as i know, is the only way to tune it, as you need to put in a "value" for all throttle positions at all engine speeds. I used the standard BB512 switch for fast idle when cold (the motec took care of the mixture) and it didn't have anything to pick up the idle speed when the A/c came on. I don't remember that being a problem though. The car was infinitely better to drive on the road than it was with carbs, and definitely made more power everywhere and started immediately hot and cold. remember, with FI there are no compromises for driveability v good power. You just set it to be spot on everywhere, and it is!
 
1 - 18 of 18 Posts
Top