Feel bad for Scott. Can easily come to believe that ITBs and new engine management will unlock a world of performance. At some level, it’s wishful thinking to avoid the multiplicative dollars required on the ground up internal work to truly move the needle. Good reminder but painful for Scott so I feel for him. That’s not any way suggesting some fault by Al - expectation is always resentment under construction (how much resentment depends on how much expectation!)

If there is a takeaway for me, it’s that a chipped motronic system is pretty adequate.

based on the dyno graphs and how my newly installed itb's affected my own car I would guess the car at discussion drives nicely and better than before. Imrovements in dyno graphs are not insignificant and problem appears to be unrealistic expectations.

There's been a lot of discussion about power increases (expected vs realized) and about drivability.
But I just got back from a 60 car rallye in the mountains of WV and I can assure you all of the ITB/EFI guys got markedly better fuel economy than the CIS guys. Doesn't sound that important until you get to the bottom of the mountain on Monday morning to tank up and head home and find there is no gas at the station. I wasn't worried as I knew my 1/2 tank would easily get me to the next station. My friend next to me in a CIS car was worried. (we did both make it to the next fuel station)

Hey Chris,

Nick here too from Ruchlos. My car on ITBs was sipping fuel too - thought i was crazy! Glad to see your car here. :) WV again soon.

Nick! Funny enough, I'm heading back to Snowshoe next month...in the 911...with my MTB on the roof. Going to try lift-access DH. Super stoked.

The 911 did get down to ~18mpg on one of my Ruchlos tanks of fuel. Probably when I got to idle up and down 11 miles of gravel mountain road...

Very cool! Since the BMW engine is an inline six, did you use 2 throttle bodies and cut off the 3 TBs on the end, to have the motors to control both banks on the Porsche? How did you adapt them to the head?

I've seen another drive/ride by wire ITB kit on Ebay from T.O.Performance , it uses some Triumph motorcycle E-TBs although I am not sure which.

https://www.ebay.com/itm/373395705361?hash=item56f01e4e11:g:-zUAAOSwu2dgLDF4

https://i.imgur.com/aWYIimJ.jpg?1

That's a clean looking setup.
On a sidenote, has anyone ever tried to adapt BMW S54 M3 throttle bodies to a flat six?

See the pictured I quoted above and the question I asked :D

:D sorry missed that part.

AFAIK , he is using Suzuki 1000cc throttle bodies , and controls them with the bmw electronic throttle motor .

Happy holidays [emoji1335]

https://uploads.tapatalk-cdn.com/202...1931189116.jpg


Sent from my iPhone using Tapatalk

Following this. Interesting!!

Post your ITB Setup
 

I have a question for the experts here. I got a great deal on a 46mm PMO ITB setup complete with engine management. I have a 2.7 RS spec engine with S spec cams. Are these 46mm PMO ITBs too big or can that be tuned in the ecu management to work? Should I be looking at reducing the 46mm ITBs?

Also Happy Holidays!

The 2.7RS is a great build and lots of fun....they make decent power and spool up nicely. I typically use 40mm ITBs for that engine configuration....and they work very well.

I expect that you could install the 46s and use the ECU to tune them up to work with your 2.7....but you would likely sacrifice smooth tip-in and low RPM torque/throttle response.....but come alive in the upper RPMs....
That, combined with the S-cams might make it ok for a track with long straights, but no fun around town or as a canyon carver....so basically sacrificing what makes that configuration so much fun.

The 46mm PMOs are really nice ITBs, but I wouldn't apply them to the 2.7RS and would save them for a hot 3.2 or a 3.6.

regards,
al

ITBs
 

Many years ago I adapted the Triumph Speed Triples to work with 911 engines.....it was a decent, affordable setup, great fun, worked pretty damn good and quite a few were installed...all over.... etc...http://forums.pelicanparts.com/uploa...1640374932.jpg
http://forums.pelicanparts.com/uploa...1640374932.jpg



now I've moved on to these....... very nice!

http://forums.pelicanparts.com/uploa...1640374932.jpg


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regards,
al

I was hoping you would chime in Al. Thanks for the feedback and information. The car isn’t going to be a track car but rather mainly street and canyon car.

I may need to start looking for replacement or someone looking to trade my 46mm ITBs for their 40s.

I have a 3.2SS (or larger) build coming up. I may be interested in trading 40s for you 46s. PM me and we can discuss.

regards,
al

Who makes those velocity stacks?

Yet another Triumph (675R) ITB setup on 3.2SS custom internals etchttps://a.d-cd.net/izjt71I8wYKFmwyOV9MSCrfO1xE-960.jpg

My ITB Setup
 

I recently purchased a 935 Style flat fan for my 4.0L 964 motor. So now I can't use the factory intake or throttle body assembly. So I decided to go ITBs, coil on plug, and MS3Pro injection.

I found two sets of BMW K1300S Motorcycle throttle bodies that came like this:

http://www.914world.com/bbs2/uploads...1656292307.jpg

I cut them apart into individual throttle bodies, removed the studs and tapped the stud holes to M6x1.0.

I already had a set of MFI throttle bodies that were so corroded that they could not be saved. So I removed the throttle shafts and linkage from the MFI throttle bodies. I opened the slots on the shafts, and the BMW throttle butterflies fit perfectly. I had to cut the end off the shaft from one of the BMW throttle bodies and weld it onto the MFI throttle body shaft so I had a TPS drive. I pressed the cross shaft bearings out of the plastic MFI stacks for reuse as well.

Using a sheet of plywood, I built a jig to hold the throttle bodies in place with the fan so I can build the linkage and wiring harness before tearing apart the current Motronic setup.

Some time spent with Fusion 360 and a purchase from Send Cut Send, and I now have this:

http://www.914world.com/bbs2/uploads...1656292090.jpg

http://www.914world.com/bbs2/uploads...1656292108.jpg

http://www.914world.com/bbs2/uploads...1656292120.jpg

http://www.914world.com/bbs2/uploads...1656292135.jpg

I still have to make the correct length linkage to go from the crossbar to the center throttle bodies. And to do that I have to buy a M5x0.8 left hand thread die. I considered drilling the throttle bodies for idle air bleed screws, but I can compensate for that with the MS3Pro programming.

This setup is going in my 914 chassis, so it will actually go in with the crossbar at the flywheel end of the motor. I am going to make a throttle cable mount that will attach to the 4-6 side throttle bodies so I can hook directly to the crossbar with no additional linkage.

Not only is that a really slick modification/conversion, it just looks so bonkers cool!!

What diameter are those bike TB's? I ran some from a 750 on a 4cyl Toyota twin cam and they were too big. When you add 6 of them, it could be too much.

They are 48mm. And this is on a 4.0L engine. So I think they are probably really close to the right size.

Clay

This is the 3.6 with PMO 46 ITBs in my ‘74. I’m running Megasquirt controlling EDIS ignition coils and batch firing Bosche 30lb injectors. The motor is all stock internals and runs Billy Boat 1.75” headers with heat. I just finished cleaning up the engine bay wiring and fuel line routing. I also modified Zenith carb bases to fit the PMO itb’s so I can run a modified factory airbox. This is the later plastic airbox as the earlier metal ones are too tall to fit on a 3.6/PMO combination without more significant mods to shorten them. The plastic air box will just barely fit as it is about .75” shorter than the metal ones.

http://forums.pelicanparts.com/uploa...1672948447.jpg

Previous dyno testing I’ve done on a 2.2s mfi motor showed the metal airbox improved midrange over K&N filters and gave up very little in top end hp. I also had my 3.8 pmo/Motec motor dyno tested with a modified metal airbox with 2nd 3” inlet to the filter on the back (towards the front of the car) of the airbox. The airbox proved to start to be limiting at over 325 hp and hard to tune and get a steady afr. That motor was comprehensively modded and made in excess of 370 hp, so the airbox was not used and I ran K&N filter hats on it.

The plastic airbox i’m using here has the same 2nd inlet on the backside and this motor should not be making more than 300hp if that. So I think it should work well. I plan to be refining the tune on the dyno in the next few months and will then be able to verify how well/not-well this plastic airbox works in this configuration.

Here’s a pic of the intake on the backside.

http://forums.pelicanparts.com/uploa...1672949161.jpg

I would love to adapt one of these to my PMOs

You should be able to run the earlier metal airbox on you 3.0 as well. I bet it would work great.

Do you know if it’ll still fit when using the tall PMO manifolds?

I cannot answer that definitively. In doing a quick search, I found that standard height pmo manifolds are 82mm and tall manifolds are 98mm. So a difference of 16mm.

I know the metal airbox will fit on PMO’s on a non 3.6. I ran one on my 2.8 SS (3.2 heads). I’m pretty sure that I had standard height manifolds on that. Maybe the metal airbox would still fit with tall manifolds, but I cannot confirm that. I do feel fairly confident that the plastic airbox would fit with the tall manifolds though. Hope this helps.

Thanks!! I have Webers and PMO tall manifolds, with those the KN filters would not fit. The rear right corner hit the grill

Check out page 7 of my build thread to see the mods I made for the bases and airbox to fit with PMO's.

http://forums.pelicanparts.com/porsche-911-technical-forum/993492-74-widebody-hot-rod-build-7.html

Could you please do me a favor and measure from the bottom of the base to the top corner of the air filter box? At rear most portion on the passenger side. I’d like to compare the height with the KN filters

Sure!

The airbox and base do not extend nearly as far to the rear of the car as do K&N hats. So we need to locate the rear edge of the air box for reference. Running a vertical line up from the rearmost edge of the right side of the airbox, that line is 145mm (5 11/16”) from the lip of the engine bay above it.

http://forums.pelicanparts.com/uploa...1673039472.jpg

From the underside of the base to the top of the rearmost lip is 78mm (3 1/16”).

http://forums.pelicanparts.com/uploa...1673039617.jpg

Let me know if you need additional measurements.

http://forums.pelicanparts.com/uploa...1673042808.jpg


William knight 3.45 built by will at fairwinds, with ATpower ITBs. Almost done with tuning but it’s coming back out for a few small adjustments and titanium retainers and valve springs.

Damn, that thing is a work of art.

http://forums.pelicanparts.com/uploa...1673050413.jpg

Clewett ITBs. Waiting on the heater ducts to be powder coated and dyno tuning but the car is running and drivable.

http://forums.pelicanparts.com/uploa...1673069047.jpg

PMO,Motec M84, SSI/Monty muffler.

Love seeing updates and pics on this thread - one of my favorites. Planning to sneak by the shop and see Mr B’s air cooled toy sometime this coming week.

Thank you very much, that’s all I needed!