I am thinking of ITBs looking for advise

[IS300]

I have been wanting to switch to ITBs from CIS want to hear your thoughts....

1982 911 SC headers, M&K gt3 exhaust ......

The cost of rebuilding CIS vs cost of the ITBs

think my cis is been F@*k with by the previous owners......

Is it worth it to upgrade to ITBs for
1 Drivability
2 Resale ... (get the cost Back)?
3 HELP

Anthony

[kenikh]

Sure, but then you have to go EFI. The slippery slope is steep and has a landing made of burning cash. There are some affordable options but you need to ask yourself: how much work can I do myself? If you're going to farm it out, it's $$$$$+. DIY $$.

Sent from my GM1915 using Tapatalk

[RSBob]

Kenik speaks truth. Cubic dollars and is not a panacea. One issue common to most systems is that you just can’t jump in a cold car and go. Instead, you may have to sit for two to three minutes so it doesn’t stall or buck your fillings out. Things mother never told me, but you need to know. There are other quirks as well, like a high idle speed, so I would highly recommend if you choose to go that route get a professional install and thoroughly discuss the differences so your expectations are properly set.

I would recommend going with a nice set of carbs. Less hassle, guaranteed throttle response, no sitting waiting for warm up. Cheaper too.

[PhillIB]

Originally Posted by RSBob

Kenik speaks truth. Cubic dollars and is not a panacea. One issue common to most systems is that you just can’t jump in a cold car and go. Instead, you may have to sit for two to three minutes so it doesn’t stall or buck your fillings out. Things mother never told me, but you need to know. There are other quirks as well, like a high idle speed, so I would highly recommend if you choose to go that route get a professional install and thoroughly discuss the differences so your expectations are properly set.

I would recommend going with a nice set of carbs. Less hassle, guaranteed throttle response, no sitting waiting for warm up.
Cheaper too.

Couldn't disagree more. I fitted my own EFI and ITBs with zero prior experience. It runs perfectly. Get in, start up, drive away. Soooo much better than the old CIS.

[Cheshire Cat]

this might help, made this thread a while ago to help peops to get in this ITB diy world, should be updated I reckon, but mostly it`s covered right
https://porscheforum.com.au/topic/12375-itb-efi-diy-guide/

[jpnovak]

This conversation is not about ITBs per se. To get to ITBs you must convert to an aftermarket EFI system. Independent of ITBs or common plenum your ultimate success will depend on your comfort level wiring up a system and then programming and then tuning for optimal performance.

An EFI system done right can be an asset to the car price. Without question an EFI system done right offers better driving character, more performance and increased fuel mileage. One hundred Percent the converse is true related to incomplete installs.

Every different EFI system has differing levels of support. Unless you are paying a shop for turn-key solutions you should carefully explore the different options, support and ease of use.

IMO, the single most important factor is tuning. It is easy to get a fuel map that runs decent. It is more difficult to optimize throttle transitions along with all 4 corners of fuel and ignition maps. ITBs magnify these tuning problems. If this is your first time tuning expect MANY hours of back and forth. If you are paying a shop, make sure they have done this type of install before or your wallet will suffer from hourly rate.

I am all for EFI conversions (Full disclosure: I make parts for conversions and do them myself). You just need an honest assessment of your capabilities and end goals and make sure these match up with your intended path to get there.

[plexiform]

www.rasantproducts.com

Call Rasant Products and discuss with Andrew Darud. He is very knowledgable and helpful. Will not rip you off but this stuff is not cheap.

[jac1976]

The slippery slope is steep and has a landing made of burning cash.

Man, I this isn’t the view I often see...

[cnielsen]

I agree with everyone, even though everyone doesn’t agree with each other! Lol.

Yes, it’s very expensive and difficult to get it right
A badly set up system will rattle your fillings out and become extremely discouraging.
Yes, it can be set up properly so it will start immediately, run smoothly and make great power. I would highly recommend having someone that has done this many times before install your system. I would also ask to drive a car or cars that they have set up. Highly recommend Motec and I would go with a well proven ITB setup like PMO’s.

[chrismorse]

Starting with my dad’s very original 74, car has been down the slippery slope, 8 years.
Being out of use for so long I was worried about gunked up cis parts. I briefly looked into having the distributor rebuilt, then what about the injectors, WUR, rubber bits and fuel lines - then finally slid a bit further down the slope and after talking with Al Kosmal, decided on the Megasquirt/PMO/EDIS package.
I went with MS rather than AEM priamily for cost containment and the MS is widely used and a lot of help is available.
I decided to use the PMO system for simplicity, solid reputation and their excellent “rain hat” air cleaner set up - it rains 50 inches a year and it will be an almost daily driver.
In doing a bit more reading, I saw a lot of emphasis on the accuracy of the timing signal to the computer. I was also wanted to upgrade to a more modern ignition system, getting rid of the distributor, so went with the EDIS and AL supplied Clewitt’s crank fire set up.

Installing the mechanical bits is straight forward wrench work. There is a bit of problem solving and fabrication work, locating the ignition components, fuse box and other electrical bits.
So far, (engine not back in the car), the most challenging element has been working out the wiring, connections and routing. I started with a new, CIS free engine harness from Timmy2, (very nice work), and am working out running the wires to provide disconnection ability for service, routing sensor wires to avoid induced voltages and Secure, waterproof wiring connections, hardware store butt crimps are not suitable.
I just received a good set of crimpers, with an assortment of jaws, bare and heat shrink connectors, with N assortment of adhesive heat shrink tubing.
So that is where I am, a first timer. Now if I can just get a little garage time...
Chris

[IS300]

thanks Chris
that helps out a lot ..
I was thinking the same on the butt crimps not being the best, could you tell me what crimpers and jaws your using???
thanks Anthony

[chrismorse]

If you look at a lot of EFI related threads, you will get an idea of the depth and complexity of how the computer gets and processes the information to provide the “BEST” fuel and ignition timing.
I have seen many go through the learning curve, fixing minor, or major electrical/sensor problems and endlessly creeping up on acceptable performance.
AL’s advice, and that of many of the cognoscenti on this board is to get it running and take it to a pro, WITH experience and a dyno.
Dyno time is expensive, (haven’t used one since college), I got an estimate of $1000.

I’m interested in others experiences, so I can plan accordingly.

It’s dark in here ;-)
chris

[chrismorse]

Originally Posted by IS300

thanks Chris
that helps out a lot ..
I was thinking the same on the butt crimps not being the best, could you tell me what crimpers and jaws your using???
thanks Anthony

Hi Anthony,
I got the Sherman SG 18960 crimping tool kit, tubing and connector assortment recommended by Winders and Timmy2, bought from amazon.
Jaw choice is determined by crimp type, (insulated or bare), wire gauge and single or double crimp.
I am leaning toward weatherpack multipul pin connectors in some places to facilitate service work and ensure a secure, positive connection. I don’t want to have the car quit or not start because a single spade connector pulled out. Just got the kit, so need to verify the weather pack suitability.
chris

[3rd_gear_Ted]

Its not about the $$$ or the integration work, its about the knowledge tune guy who can physically show up @ the dyno you are using for the final tune.
Remote tune sessions don't ever get the knowledgeable second set of eyeballs on your integration to cure design issues you will chase your tail on.

[chrismorse]

Originally Posted by 3rd_gear_Ted

Its not about the $$$ or the integration work, its about the knowledge tune guy who can physically show up @ the dyno you are using for the final tune.
Remote tune sessions don't ever get the knowledgeable second set of eyeballs on your integration to cure design issues you will chase your tail on.

Hi Ted,
I agree, it is kind of futile/questionably effective and expensive to hit the dyno without a good solidly recommended/experienced pro to set up your tables.
Al recommended a guy in the Bay Area that I will probably use to dial in the Megasquirt.
HPs book on EFI/engine management suggested:
Make sure your cooling system is comfortably adequate, not leaking. (I would take that one big step further - have more cooling capacity than you are likely to need and let the thermostat keep it under control).
Make sure your fuel supply and return lines - connections are not leaking.
Have the ignition system dialed in. All fluids topped up and ITBs balanced.
Have the fuel and ignition systems in their optimal condition. Dyno time is expensive to try various different possible development combinations, this or that muffler, plug, ignition system. Get the car as ready as you can and let them use the dyno to set the table values.

I live about 5 hours from the Bay Area, so I need to plan on a motel for a couple of nights and bring a bag of cash. Hope the drive home is full of grins.

Any other thoughts on getting ready for the dyno/pro???

Thanks,
chris

[iamheretolurk]

Without a doubt, you MUST use Al Kosmal's kits from the X-Faktory. The RHD ITBs and megasquirt combination are amazing. I've only continually been impressed by the kit and his continued support.

The whole kit is well thought out.

[LUFTKUL]

You should have the small 34/35?mm intake port heads. I'm not sure there was a great option for ITBs with those heads unless you are going to have them ported to the Euro 78-83 or US 78-79 SC size. Others more knowledgeable please correct me.

[dfhtrhjn]

I was thinking about ITBs to replace the CIS on my IROC and I've got the same issue everyone else has mentioned, which is after the basic mechanical install how do I tune it correctly. This is why I'll probably end up with carbs again.

[Dpmulvan]

Originally Posted by LUFTKUL

You should have the small 34/35?mm intake port heads. I'm not sure there was a great option for ITBs with those heads unless you are going to have them ported to the Euro 78-83 or US 78-79 SC size. Others more knowledgeable please correct me.

You have been corrected.

[Dpmulvan]

Did you check these guys out. Mike from Montreal aka grip911 recommended these guys.
Simple Digital System EM-5