Anyone do a Motec FI conversion

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

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

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

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

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?

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

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

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

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

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

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