I have been running 45 dells on 2270 with 34mm vents. Not sure if it was the cam choice (163/86b0, but it was much easier to drive with than with the 38/39 vents.

I was going to gut my spare dells for this project, but I think they are worth more in the box.

So, for street 2270 what size motorcycle from wich bike tb should I be looking at for a first build?

Thanks in advance,
Carlos

Talk with Mark Henry, who has bike ITB's on one of his motors. I have some GSXR1000 throttle bodies in a box somewhere, which are either 38 or 42 mm, but never used them in favor of a single TB. Thinking at the time was that bike's red line is twice what my 2270 was and throttle bodies don't have a venturi so they can move more air than a similarly sized carb, plus the injectors are already sized right. Sounds logical enough, but MH has direct experience.

I'd look for something around 40mm, mine are 46mm, but I have a 2.6L engine.

You need to find an bike TB assembly that comes apart into 4 separate ITB's, late 90's GSXR are a common choice but there are others.

This is not a project for a beginner, you need access to a mill, lathe, welder etc..
Also if your time is money you might want to consider the CB TB's.


http://www.914world.com/bbs2/index.php?sho...p;#entry1862152

Hi Mark

I was hoping you would chime in. I read your thread 3 times.

I guess my question is with the larger bores, the intake velocity slows. Is this a non issue with ITB's? Do we choke the bores of the carbs to compensate for an analog fuel delivery system? That would make sense to me. But I'm a dope. Ask my ex.

Carlos

great to see the annual motorcycle ITB project will start.
I hope you document how you do it.

rich

ITBs that are too big will limit part throttle resolution. A small change in throttle makes a big change in air flow.

ITBs that are too small can choke off the top end.

I agree with Mark that 40s would probably be a good choice, but you could go up to 44. There probably isn't a distinct advantage to any size in that range, unless you're planning on dyno tuning everything and swapping ITB sizes to check everything.

If you want something that goes in pretty easily get the ITB's sold by Mario at Thedubshop, they mount right onto a EMPI IDF intake, complete the kit with Tangerineracings Cable throttle kit and you'll have a nice setup.

I went with the 40 mm size for my stockish 2.0 but I have a spare 1,7 that I'll have built into a 2270 or 2316.

http://www.914world.com/bbs2/uploads_offsi...458131052.1.jpg

Actually the choke in a carb the proper name is 'venturi' and what it does is it speeds up the air, creating a substantial turbulence to atomize the fuel for a proper burn. It also helps to suck the fuel from the carb (bowl) at a metered rate.
A fuel injection TB doesn't need this as the injector atomizes the pressurized fuel.

Search the venturi effect.

As a general rule, you step one size DOWN for ITBs when switching from carbs. ITBs flow like crazy. I wouldn't go bigger than a 40mm. That said I have 45mm ITBs on my 2316cc and they are a bit too large. 42s would probably be more appropriate.

I second Mats suggestion of the ITBs from Mario (www.thedubshop.net) and Tangerine racing's cable linkage. The linkage is like butter and I havent touched it in 18 months (20K miles) and it was still spot-on 2 weeks ago when I checked with my flow meters. You'll NEVER say that abut X-bar or even twist style linkage.

I've never touched my center pull, but I did build it myself. Also never had to touch Gene Berg cross bar, but that's T1 only...just saying it can be done right, but rarely is.

this is awesome.......valuable comment I know

You know the one thing I would do if I had a T4 (your size, 2270) 914 again would be to modify a a D-jet intake for a single mustang 75mm TB. Then drive it and learn how to tune the FI system.


I know for sure it would be easier to tune and you could take your time building an ITB system for later while still driving.
I did this on my first build with a 2.0, mild cam and all stock intake (stock 914 TB). I admit it was the smoothest, most stock like operating system I've ever built.
Systems...I've done a few stock engines like this.

I know Jake doesn't like a single because you lose some HP, but to me sometimes it's worth it.

Programmable FI is a steep learning curve and it would be one less thing in the mix while you are learning.

Single TB intakes are more friendly.

Mark,

I have kicked this around also.
Mustang MAF, 1.8 914 or 2.0 bus plenum, 944 throttle body. Upsides is that I would only have to source the MAF.

Carlos

its not a non issue but its less of a issue because the throttle is not depending on air speed for mixing fuel the injector atomizes it for you.

you likely want anything you can find in a 40-46

Why do you need a MAF? are you trying to mod an L-jet system?

Most aftermarket systems use a MAP sensor and this is what causes issues with low vacuum, hot cam, ITB engines.
Simplified explanation is this causes issues with low MAP signal resolution resulting is a bad accel curve.

[quote name='Mark Henry' date='Mar 16 2016, 11:25 AM' post='2316528']

[/quote]

Why do you need a MAF? are you trying to mod an L-jet system?

Most aftermarket systems use a MAP sensor and this is what causes issues with low vacuum, hot cam, ITB engines.
Simplified explanation is this causes issues with low MAP signal resolution resulting is a bad accel curve.
[/quote]

MS will do heated wire MAF which would take care MAP resolution problems with cam.

My big valve heads were made on a 1.8 casting. I still have 4 bolts intake setup, so I have to use 1.8 runners.

Using a 1.8 or 2.0 bus plenum will allow room to install the MAF, since the throttle body is on the side instead of the top.

I reread your post and a 75 mm mustang throtte body seems huge.

Carlos

humor me please,

a 40mm weber or dell gets sized down to 34mm with the venturi.
ignoring the reason, to get the fuel to atomize better, the net result is still a 34 mm hole letting air into the intake, not a 40mm hole.

So, why would a 40mm hole work fine (magically) for a FI system?
The air charge will now be slower.
I understand the fuel atomization is no longer an issue, and its not what I am talking about here...its purely the volume and speed of the air.

I know the motor will only take what it needs for air, that is reality.
Would it not work fine with 34mm ITB's?

I have a set of 40mm duel throttle bodies sitting here....the super long term project if i ever get up the nerve to do a programmable FI system.

Also, if I have say 46mm intake valves....wouldnt I want 46mm throttle bodies?

Well, air can be compressed, so it's temporarily squeezed through the 34mm venturi, but afterwards expands back to 40mm. Means that on either side of that 34mm venturi the air is flowing in a 40mm tube, same size tube as that 40mm throttle body, with the same velocity and volume.

And when that 46mm valve opens it doesn't get totally out of the way leaving an empty 46mm hole, there's still some obstruction there, so a 40mm throttle body can supply what's needed, and at a pretty nice velocity.

I suggest that you look at Al Ikosmal threads on pelican. http://forums.pelicanparts.com/911-engine-...fi-systems.html as one example

There are many other ITB threads over there and a few on the VW sites. The displacements from 911 to 914 are similar per clyinder so sizing will be somewhat comparable

I would not go against Marks knowledge and experience but I seem to recall that Al uses smaller ITB's with great success. His go to is from the triumph speed triple I think.

Check it out

A plenum based system is easier to tune and will net you more hp & torque down low on the RPM range. Plus they are just easier to set-up and tune to some extent. A 75mm TB on a factory 2.0L plenum is absolutely HUGE and I would expect tip-in tuning issues going that large. I would look into a Jeep straight-6 TB since they are around 60mm (up from the factory 50mm for the 2.0L) and have an integrated IAC valve.

Then get a pair of these ends and make your own runners with mandrel bent tubing.






Use 1.625" tubing and you've got one hell of an intake system.

You right 75mm is too big my bad. It's been a few years since I looked into it last, so I was working from memory.
How I got the figure is Ford performance guys are removing stock TB's and replacing them with aftermarket 75mm TB's, Thus stock mustang TB's can be had for cheap.
The stock Mustang TB I have in front of me and pictured below is 60mm.

If you used a pair of those ends you could do a DIY intake like Nate said.
Here are a couple of how to's, first one is a subi so it's actually close to what you would need.

http://www.sdsefi.com/air12.html
http://www.sdsefi.com/techinta.htm

I decided to back burner ITBs. I did a little bit of math, went through my boxes and this is my plan. Based on this math.

My cam is all in @7200 rpm. displacement=2270cc ( 138.52 ci)+10%
Math says (((7200/2)*138.52)/1728)*1.1=318 cfm. That puts me in the 944 throttle body range and I have a box of 4. (Good thig I paid 130k for the BSCE @ private college for my son. How is that for ROI?)

The advantage is that it is much easier to bore the plenum out more if I'm not making the required air. If that is still not enough, it will be time to fab a custom plenum and runners.


2.1 liter waterboxer plenum( in the mail), 944 tb in hand. Stock intake runners. MS in hand, trigger wheel in hand. I dropped my motor over the weekend and and expect to have this ready for MS Sunday night. I have a shot at having it ready to go for Hershey, otherwise would it be OK for me to park a 928 in the 914 area?

Even if it is not perfect, I think I'm on the right track. I think that all of these tb sizies are overblown. My personal experenice with dellorttos is that I had to swap vwnts from 38 to 34. My other experience is the long a project sits, the less likely it ever get finished.

If I'm wrong it won't be the first time. Ask my ex.


Carlos

How big is the vanagon plenum?
As a rule of thumb for performance you want your plenum to have the same volume as the engine, so in your case about 2.25L.
Just a little bigger than two quart bottles of oil put together.

I think the stock bore for a 2.0 throttle body is 45mm. I run a modified volvo throttle body. It is 55mm. The engine size on the 90s Volvo it came from is 2270. I figured it would be a good choice and it was. The Volvo TB requires some mods. it turns the opposite direction and also required me to drill and add a vacuum advance or retard port. I can remember which. I made an adapter plate to fit the stock plenum out of a chunk of 1/2" aluminum plate to test it out. It worked for a couple of years until a machinest I met saw it and modified another plenum properly. I run a modified Djet system. Web cam fuel injection grind. Torquey SOB!

What system are you running?

The D-jet plenum is up somewhere around 2.5L IIRC

Djet works up to 2.4 tested.....not sure of anything higher.
I did 2.4 because I could not find any factual cars, just urban myths.

I will say that I did a lot of research and stuck with the stock stroke crank, and fairly stock camshaft....a little change there, but typical early ramp up on the lobs.

I recall, but it's foggy, that the longer stroke does some funky things to the air in the plenum and the djet did not like it...
At 2.4 which was 71/103 it works fine using the maps from a 411 which removes one of the diaphragms and gave me a simple fixed external adjustment....made tuning fairly straight forward.

Rich

It is nearly stock Djet. Early 2.0 injectors and MPS. 425 ohm resistor in line with the head sensor. I bumped the fuel pressure up to 36 psi

Update.

Junkyard shopping list
55 mm throttlebody with angular tps and heated wire MAF.
vanagon 2.1 plenum arrives Monday.
Motor is down and out and on engine stand.
MS arrives this evening.
Runners, injectors, triggerwheel gaskets, seals in hand.

Looking for location tips for MS. Inside cabin or in engine bay. In either case, I am looking to get some type of single weather proof connection to ECU to make engine drops less complicated.

Why am I using 2.1 bus plenum? I have just one 2.0 plenum left, this is the biggest reason. I also read on STF a while ago that there is something different about a this waterboxer plenum that makes it more efficent than a 2.0 plenum. STF is down, otherwise I would post a link. I need the throotle body to exit the side of the plenum so I have room to add a heated wire MAF. I'm thinking that I will be half way to a forced induction system.

Im planning to run my Unilite in the beginning so that I can log the advance curve and use that as my starting point to build the spark advance table.

Time to see . Junkyard Barbie

Progess to date.

Vanagon 2.1 plenum is a dead end I think. Volome is approximately 1600 cc. Also the throttle body is at one end so there are two favored and two disadvantataged runners. Although it comes with a 50mm tb, there doesn't seem to be enough rom for a 55-58 mm tb.

So, I pulled my last 2.0 plenum out of the box. First advantage, tb is more centrally located, runners should be appear to be the same. Volume is approx 2350 cc min., (+- measurement losses).
I wanted to avoid using a 2.0 plenum because I expect that i will need a MAF to since I am currently on a split durarion 163/86b cam. (plus it was the last one in the box). I'm married to 2.0 plenum now.

Motor is on stand, I will do leakdown, plenum packed for trip to machine shop. Need to puzzle out the volvo tb. It pulls in the wrong direction. Prepped the runners for powder. Prepped headers for paint. Pulled out heat exchangers and triad. I am going to test this with headers and heat exchangers.

At this point, Im going with 2.0 green injectors. I have them. I am looking for a 2270 MSQ file if someone can pm one to me great.

I'm hoping to fire this up next weekend.

The 914 injectors are low impedance so you will have to run a resistor pack.

The factory D-jet plenum will work and you can find a used one cheap to replace it if needed.
Personally I would use the d-jet so you can drive now, but build a SDS style intake along the lines in the link below. They do state "Velocity stacks to go on the end of the runners were shown to improve airflow by 19% on the flow bench over straight tubes."
With that kind of improvement I'd be giving it a go.

http://www.sdsefi.com/air12.html

The vanagon plenum won't be a complete waste I don't have the tooling to make a velocity stack. I expect to cut it up and use the stacks if a custom plenum is needed.
Carlos

As I am still waiting for the machinist, I need to decide on temp sensor. I see two part numbers available.

0 280 130 003 1.7
0 280 130 012 2.0.

I'm guessing that I can use either one,

I'm thinking this is going to sit on my 2.3 /6 911 motor that we are building.

Has anybody here looked at this stuff?

http://www.jenvey.co.uk

Not trying to change your mind, but I think this is wrong. Or rather, I think that the side inlet plenum has a huge advantage in smoother air flow. The 2.0 plenum forces the air directly into a wall/floor which means you have no velocity. The side inlet plenums allow air to smoothly enter the chamber.

Just my armchair engineering at work.

Mario from thedubshop.net builds 911 kits with Jenvey ITBs.
Click to view attachment





With a carb where that air also has heavy fuel dispersed in the air charge, that will be true, and charge robbing occurrs. With an EFI plenum, you are only moving the air. The bus/Vanagon/1.8L Porsche plenums work very well on bigger displacement motors over the stock 2.0L plenum.

The D-jet intake would be ok to get thinks up and running quickly, but I'd still look at the SDS intake I linked to in my last post.

That link is a subaru plenum so of course you would have to tweak the design.
Note how it feeds direct across the runners and that the runner inlets are shaped like velocity stacks.
Long known fact that the velocity stack shape increases airflow and thus power.

If you have 2.0 914 heads you likely could mod D-jet runners and build a custom plenum.

Hi,

This is an update to explain where I am at currently and how I intend to go forward.

I'm married to water over plenum at the moment. Forgot that my big valve heads are built on a 1.8 casting. 1.8 runners won't fit with a 2.0 plenum. I'm not cutting any parts yet.

After careful measurement of 1.8 runners, the intake flange from the dubshop is backseated. I can get the same runner ID with the stock 1.8 runners. At the moment, just waiting on the powder coater.

Carlos

I played around with this a good bit in 2003-05. I found that unless the plenum capacity was at least 75% of the swept volume of the engine, that you'd lose big power with a plenum. This was despite the size of the TB thats used.

I also found that the plenums radically effect camshaft selection. Idle and low speed performance were greatly impacted when using the cams that work best with ITBs and carbs for us. I had to alter lobe separation to increase the vacuum signal, and make the engine run down low.

I was never pleased with it, way too many compromises for me.

Hi,

Just wanted to update this thread with what I know at the moment.

I don't think there is any measurable difference in volume between a 1.8 and a 2.1 waterboxer plenum, except the throttlebody mount. waterboxer is bigger, but not big enough for my volvo TB. I am going to setup for the 2.1 waterboxer plenum.

I think the overall volume is too small for 2270, but I am prepared to live with it while I cobble everything together. I always expected that I will have to do a custom plenum similar to what Mark Henry has posted on this thread.

If you want to post some empirical data regarding plenum volume and performance feel free.

Dont post internet heresay.I have cc'ed all of these plenums. I am willing to discuss "informed opinions". I'm trying to learn something.

Carlos