Airflow/Horsepower limit for stock 2.0L intake system? Options

[greggearhead]

OMG - are you guys even reading my post?

I already have the largest throttle body, largest plenum and largest runners. I asked about if anyone knew the limit of the factory components because I am switching to ITBs. I'm not asking about making an intake manifold, or adapting varioram, or changing the plenum, etc.

I've used ITBs on lots and lots of different engines over the years, and throttle response, when tuned correctly, is usually noticeably much better. I'm not asking about those things.

[GregAmy]

I asked about if anyone knew the limit of the factory components.

No. No one knows. Everyone that cares about performance goes to Webers IDFs, or Dellorto DRLAs, or dual-choke intakes and EFI.

The stock intake was designed for 100hp. OF COURSE it won't be as good as individual 40mm chokes. Duh.

Install the ITBs and be happy.

[Mark Henry]

Are you reading my posts?

I run 46mm gxsr bike TB's so a good machinist could cut the top off of existing T4 alunimum weber manifold and weld up a shorty base to adapt a bike TB or the CB performance TBs. It still won't be perfect, but it would work.

edit I'm talking about ITB's here, I think most here would know that.

No one makes a 411/412 shorty intake manifold, so either you do a hack job to your engine hatch and stick ITB's out of the holes or you do the above.

[greggearhead]

It's a 412! There is no engine hatch!

[greggearhead]

Are you reading my posts?

I run 46mm gxsr bike TB's so a good machinist could cut the top off of existing T4 alunimum weber manifold and weld up a shorty base to adapt a bike TB or the CB performance TBs. It still won't be perfect, but it would work.

edit I'm talking about ITB's here, I think most here would know that.

No one makes a 411/412 shorty intake manifold, so either you do a hack job to your engine hatch and stick ITB's out of the holes or you do the above.

Again - did I ask anywhere about fitting ITBs?

No.

Did I ask about what ITBs to use?

No.

Did you see my post where I talked about having used ITBs (in fuel injection and carburetor form) many times over the years?

Apparently not.

Moderators - I'm fine with locking or deleting this thread. There is no good info coming out of it and no good discussion about the topic.

[Superhawk996]

(IMG:style_emoticons/default/WTF.gif)

(IMG:style_emoticons/default/popcorn[1].gif)

[GregAmy]

I think we're done here.

But while I have everyone else's attention...will the 2L 914 TB fit easily on the bus plenum? You may recall - if you read my friggin post! - that I'm developing a system to fit on my 2L 914 per SCCA Limited Prep regs, which requires use of the stock unmodified throttle body. Everything else is free. So if the 914 2L runners are good, maybe I can adapt that to a better plenum and run from there.

I suppose I could look into modifying anything, or fabricating from scratch. Would much prefer an "easy button".

As a related aside, my 914 does have a decklid over the engine, so no clearance concerns.

Thanks!

[Bleyseng]

OK, I did search, and couldn't really find anything.

My basic question - when does the 914 2.0L intake become a restriction to power?

I have a built VW 412 -

2056 cc Type 4
* 9550 RAT cam
* LE-180 heads (914 2L combustion chamber, 42mm intake, 36mm exhaust)
* Mallory Unilite vacuum advance distributor, Mallory Promaster coil, Mallory Hyfire CDI
* Stock 412 heater boxes & Thunderbird exhaust
* 2L Bus plenum and throttle body
* 2L 914 runners
* Ford "Design II" F1TE-D9A (Bosch 0280150947) 24# injectors (modified)
* SDS programmable EFI
* Oil bath air cleaner housing modified to use large circular filter element


I have a pair of IDF manifolds, and some VFR throttle bodies. Roughly equivalent to Weber 40IDFs (maybe a bit better in terms of flow). Engine made 115hp at the wheels. I'm just wondering if the (improved) stock intake is a cork or not?


(IMG:http://www.914world.com/bbs2/uploads_offsite/i61.photobucket.com-12836-1576171976.1.jpg)

From what IIRC the 914 2.0L intake setup flows pretty well until about 130hp. The Bus 2.0L plenum with mods goes past that due to its better flow (sidedraft vs downdraft) according to tests Raby did years ago. Your pic shows the bus setup so you are set.

[Mark Henry]

From what IIRC the 914 2.0L intake setup flows pretty well until about 130hp. The Bus 2.0L plenum with mods goes past that due to its better flow (sidedraft vs downdraft) according to tests Raby did years ago. Your pic shows the bus setup so you are set.

IIRC that was on a 2276cc engine.

[Mark Henry]

I think we're done here.

But while I have everyone else's attention...will the 2L 914 TB fit easily on the bus plenum? You may recall - if you read my friggin post! - that I'm developing a system to fit on my 2L 914 per SCCA Limited Prep regs, which requires use of the stock unmodified throttle body. Everything else is free. So if the 914 2L runners are good, maybe I can adapt that to a better plenum and run from there.

I suppose I could look into modifying anything, or fabricating from scratch. Would much prefer an "easy button".

As a related aside, my 914 does have a decklid over the engine, so no clearance concerns.

Thanks!

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

[GregAmy]

Nice...that's some clean work right there.

[TargaToy]

That does look very doable, doesn’t it?

[ChrisFoley]

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

I suppose I could look into modifying anything, or fabricating from scratch. Would much prefer an "easy button".

Greg, I have an SDS ECU if you want a real simple processor for your race car.
I thought the HP rules were for a 1.8L engine, in which case the 2L TB isn't the one you need to use. If you are allowed to use the Bus plenum and 2L runners (requires 2L intake bolt pattern on the heads) I'm sure the 1.8L TB can be fitted to it and altered to include TPS.

[porschetub]

Are you reading my posts?

I run 46mm gxsr bike TB's so a good machinist could cut the top off of existing T4 alunimum weber manifold and weld up a shorty base to adapt a bike TB or the CB performance TBs. It still won't be perfect, but it would work.

edit I'm talking about ITB's here, I think most here would know that.

No one makes a 411/412 shorty intake manifold, so either you do a hack job to your engine hatch and stick ITB's out of the holes or you do the above.

Just used short T4 Weber pattern manifolds match ported to heads but don't believe they are made anymore,sometimes see these in the FS section.
.
They have a PITA outside bolt hole setup that requires much longer manifold studs but are otherwise a good casting.

I think the only real "bottleneck" in this engine would be the exhaust ,dependant whats been done to the exhaust ports a tuned performance header and muffler would certainly help.
Is it true the Vanagon (T25) has an even larger plenum body but the runners are still the same size ?,if so why not use that with a bored out 2L bus TB with larger throttle plate.
By the way Greg "chill out" no need for comments like that

[Mikey914]

From my experience the stock set up 2.0 will easily handle the airflow you are talking about, even with larger valves.
If you build a higher reving motor you would have some issues top end, but with you can selection the 2056 would be just fine.

I think since you have the IBTs every one thinks you are going that direction.

[GregAmy]

I thought the HP rules were for a 1.8L engine, in which case the 2L TB isn't the one you need to use. If you are allowed to use the Bus plenum and 2L runners (requires 2L intake bolt pattern on the heads) I'm sure the 1.8L TB can be fitted to it and altered to include TPS.

January Fastrack just came out; they rejected my request to run the 2L engine in H Production Limited Prep, stating it has "too much displacement".

I'm not taking the 1.8L engine into HProd on Limited Prep regs; I just don't think it has a chance there, starting with 76hp versus the 2019 champ's 91hp OHC 3-valve, and the 914 has to weigh 200 pounds more on top of that. Juice ain't worth the squeeze.

I think the killer car in HP now is the 2015 Honda Fit, which start with 130 crank HP and only has to weigh 150# more than the 1.8L 914. And we're going to America's Dyno, Road America, for this years' Runoffs.

I want to develop something for my 2L street car that could be adapted to the 2L race car, ifn' they ever changed their mind about allowing the 2L into HP using Limited Prep regs; to do that requires the 2L TB.

[Superhawk996]

In so many ways this is why I got out of racing (IMG:style_emoticons/default/sad.gif) . . . too many rules that make no sense. Too much politics in making the rules.

If I wan't politics I'll watch the clown shows on the boob tube! (IMG:style_emoticons/default/blink.gif)

[JamesM]

OMG - are you guys even reading my post?

I already have the largest throttle body, largest plenum and largest runners. I asked about if anyone knew the limit of the factory components because I am switching to ITBs. I'm not asking about making an intake manifold, or adapting varioram, or changing the plenum, etc.

I've used ITBs on lots and lots of different engines over the years, and throttle response, when tuned correctly, is usually noticeably much better. I'm not asking about those things.

I am reading your post, and you dont have the largest throttle body (IMG:style_emoticons/default/tongue.gif)

The late vanagon 2.1 throttle body is larger ~50mm

back to your question though, I dont have the sources in front of me but I remember reading at one point that the 1.8 intake flows enough for ~140+ HP. With the bus 2.0 intake being of similar design I would imagine it would be similar flow as long as you have swapped for the larger 914 intake runners. Personally I prefer the 1.8 intake + 50mm Vanagon TB to the bus 2.0+runner swap, basically trade some plenum volume for cleaner intake runner path. Not sure it makes much difference, its just an easier install and I like how it looks.

With a 2056 and 9550 cam I doubt you are giving up anything power wise with that intake setup You would need more exhaust and cam before the intake becomes the limiting factor. Throttle response is another story, ITBs may help there though I found with a LOT of work on the tune my throttle response is pretty damn good. You may loose some low/mid torque along with precision in your throttle control with the ITBs swap so that is something to think about. With 40mm ITBs you will maybe get about 20-25% of your throttle motion in the lower RPM ranges before you are basically WOT. For autocross I prefer having more precise throttle control, but that is just personal preference.

[greggearhead]

OK, just an update now that this thread has cooled down, lol.

I've got the VFR ITBs mounted, linkage modified and mounted, and using IDF velocity stacks that bolt on with a little filing to the mounting holes and line up very well.

[914werke]

Was this car in WA? I recall a car that stopped in I swear was identical.