Project ITBs: Part 1-parts arrive

[safe]

Thanks for your kind words!
I'll paint the stacks with por-15, that will cover up a lot of the roughness, and call that good enough.

I have never counted hours working on my Porsche, it's not work, it's fun time!

[safe]

I have now come a little further along with the project. I have gotten the throttle linkage set up, no pictures of that yet, and I'm also on the way of fabricating air filter boxes.

I have also begun thinking of the fuel system and I have some questions about that, I hope someone can answer them for me

1. Will my -77 CIS fuel pump be alright to use for, lets say 250 HP?
I will only run between 2.5 and 3 bars (about 36-44 psi) of fuel pressure.

2. I'd like this to be a "bolt on/bolt off" engine transplant so I can swap engines for Sweden's equivalent of MOT/smog testing.
So can I leave the fuel accumulator in place in the fuel system or will it mess something up?

[safe]

Originally Posted by safe

1. Will my -77 CIS fuel pump be alright to use for, lets say 250 HP?
I will only run between 2.5 and 3 bars (about 36-44 psi) of fuel pressure.

Answering myself on this one:
The CIS pump for an 74-77 should be good for 1700cc/min, at least that is the minimum specification in the workshop manual (850cc /30 sec). An SC pump is even larger at 1000 cc/ 30 sec.

That 1700cc is at system pressure that is between 4.5 and 5.2 bars, higher than any EFI system. Most modern injectors are made for 3 bars, you could use up to 4 bars but that is the limit.

According to the book "4 stroke performance tuning" the fuel delivery formula is HP*0.6 for an NA engine, so 1700cc should be good for at least 280 hp.
Taking into account that the CIS pump is made for a higher pressure and that 1700 cc is a minimum I should be just fine!

[Rick_Eberle]

Hi there,

Just to add a data point, I've been running '04 GSXR1000 ITBs for about 10,000 miles in a 914/4. I used the Suzuki Cable linkage with a bell crank set up mounted on the TIV air cleaner bracket.

I cut up IDF manifolds (to make them 80mm center to center), and did the same for the air filters. I used two sets of ITBs, and used the linkage side of each.

[KobaltBlau]

Cool! Thanks for contributing that, Rick. It's awesome to see the setups people have and are coming up with.

[safe]

Guess I should post the progress.

I have finished most of the fabrication.

Throttle linkage, using one cable to each bank:


Custom fuel rail and air cleaners:


Hopefully it will be up and running in April.

[RWebb]

great to see this revived!

that fabbed mount won't bend will it?

[SCWDP911]

Wow, looking great Magnus. I was wondeirng if you had finished yet. Good to see the project is stil coming along.

[safe]

Originally Posted by RWebb

great to see this revived!

that fabbed mount won't bend will it?

No way, its extremely sturdy.

[shbop]

Nice work Magnus. Clever idea on the throttle cables. I like the adjustment for side to side. How did you manage the individuals on each bank?

[safe]

Originally Posted by shbop

Nice work Magnus. Clever idea on the throttle cables. I like the adjustment for side to side. How did you manage the individuals on each bank?

Thanks!
One good thing I got by using the cables is that I will get a more liner throttle opening because the pully on the housing is ofcenter. That means I will have finer throttle control of idle.

Made some small "arms" with an adjustment screw between them.

[RWebb]

that thing is crying out for an Allen head cap screw...

[safe]

It's an old picture

[safe]

Remembered this thread again.



Engine has been in the car now for a few weeks now. Its mapped and dynoed, everything is running OK, a little rich maybe, it barely does 17 mpg on mostly highway use!
I have to run it stinking rich when cold (well, not fully warm) otherwise its hopeless on light throttle.

I think an o2 sensor is called for to make it run leaner on light loads (cruising).


Taking it to the track for the first time (the engine) on Sunday!
Have done a few auto-x with it already, its a little hard to get used to. I don't need to use much throttle at all, BIG throttle bodies...

[SCWDP911]

Hope you get it all sorted soon. Looks freakin awesome!

[73rustbucket]

Originally Posted by safe

Have done a few auto-x with it already, its a little hard to get used to. I don't need to use much throttle at all, BIG throttle bodies...

Try making a more non-linear throttle by moving cable mounting position. Having the first 1/2 of pedal travel move the butterflies very little makes it easier to modulate the throttle, hence a faster car.

[safe]

Originally Posted by Shane Van Wey

Hope you get it all sorted soon. Looks freakin awesome!

Thanks! It is awesome! Loads of power and noise!

[KobaltBlau]

Magnus thanks for taking the time to continue to update this. What are your tuning plans? Do you have a wideband O2? Maybe a dyno tune at some point?

[safe]

Originally Posted by 73rustbucket

Try making a more non-linear throttle by moving cable mounting position. Having the first 1/2 of pedal travel move the butterflies very little makes it easier to modulate the throttle, hence a faster car.

It already has a non linear pully on the thottle shafts but I'll see if I can modify it a little more.
I'll think I'll try to find som better throttle cables also, the one I have are the very cheap kind and there is a little to much friction. I'll drive this summer as it is to evaluate everything and make changes under winter time.

[safe]

Originally Posted by KobaltBlau

Magnus thanks for taking the time to continue to update this. What are your tuning plans? Do you have a wideband O2? Maybe a dyno tune at some point?

No wideband, I hade one but that one failed somehow.

When I finished I just got the engine running and then took it on a trailer to a skilled engine guy.
He had it tuned on the dyno in 2 hours. Not counting the 4 hours of troubleshooting due to my wiring and a bad, but still working, ignition coil....
Total 6 hours ~$7-800, by far the best money I spent on the project.

What lacks are fine tuning the cold mapping and other correction maps, no big deal.