Better performance from Weber 32/36 or FI swap?

[wegweiser]

Hrmmm…. assuming the car came with standard low compression US pistons:

 

Spend 2 hours re-sealing the carb…or:

 

For tii conversion: Several days swapping timing cover, all linkage (from firewall to pump and throttle body), intake assembly, throttle body, coolant housing for temp/time switch,  different coolant and oil hoses, synchronizing the linkage properly…installing new pump drive belt, throttle pedal and floor stop, running fuel lines, different alternator, fuel pump, wiring, cold start assemblies, cylinder head (with different / larger intake valves, if using an early 121 head) replacing fuel tank, making sure the advance curve of your distributor matches the fuel delivery curve of the injection pump (it matters), drilling the side of the engine block to accept the oil return line off the injection pump, and a hundred other items… and THEN hoping the $650 (EACH!) fuel injectors are working properly, or the $250 cold start injector doesn't dribble…. uh… are you kidding? ...Plus the requirement of special tuning tools…. and $200 won't even buy you the tii specific coolant / oil hoses, these days. (You're not REALLY going to reinstall 40 year old used tii coolant hoses and tii specific water pump, are you?)

 

The tii system is elegant and bulletproof (when set up and maintained by an experienced person), but it is not for the novice. The horsepower gains from the tii come largely from the higher compression pistons. The smoothness and efficiency come from the injection. 

 

If you think a tii conversion is easy, or even REMOTELY on the same level as rebuilding or modifying a carb, you will be way over your head in about an hour. Don't do it. What others have said regarding carb options makes sense…but if you're running 8:1 pistons…you may still be disappointed. There's no substitute for high compression pistons (or displacement), if performance is your goal. Try a simple by-the-book tune up (ignition timing, valve adjustment, ignition parts, etc) first. Tune ups are FREE horsepower!

 

 

Edited August 6, 2018 by wegweiser

[jrhone]

Thanks Weg, i was going to chime in here because I would not be installing a Tii injection system in a car. I’d go EFI.  There is so much work involved in the Tii system and then you decide to put a cam in it,  it throws the system out of wack.  It doesn’t respond well to engine mods. While you can get 130hp out of the engine you are really stuck there for the most part.  On a carb’d system you can go bigger Pistons, cam, carbs (32/36, 38/38 or dual dcoe 40s and 45s), Exhaust and you can reliably get 150 hp out of it.  Oh and Weg you forgot the Tii brake booster lol.  Oh and how much is it to rebuild the Tii Kugelfischer? And no you can’t do it yourself, need special tools and only a few people in the US do it.  If you want fuel injection the e30 M10 fuel injection with the 325i throttle body is a much better system that can be had pretty cheap and bolt right on.  You still need a controller like a megasquirt but there are plenty out there that run it and it can be tweaked for ITBs and all mods.  

[Dudeland]

If you want to get an idea of what the difference is, take a look at this.  Not the same car but a swap none the less.  

 

 

 

[jrhone]

8 hours ago, Dudeland said:

If you want to get an idea of what the difference is, take a look at this.  Not the same car but a swap none the less.  

 

 

 

 

All that for 10hp?!  Lol.  And that was wit ITBs and Halltech EFI on a high compression motor.  And yes that was 131 at the wheels so probably around 160 at the crank. I guess that’s about the max a 2 liter 8 valve normally aspirated engine is gonna give you on the street.  So 140s with the Weber siderdrafts and 150s with ITBs and EFI. Interesting.  

Edited August 7, 2018 by jrhone

[Mucci]

5 hours ago, jrhone said:

 

All that for 10hp?!  Lol.  And that was wit ITBs and Halltech EFI on a high compression motor.  And yes that was 131 at the wheels so probably around 160 at the crank. I guess that’s about the max a 2 liter 8 valve normally aspirated engine is gonna give you on the street.  So 140s with the Weber siderdrafts and 150s with ITBs and EFI. Interesting.  

 

Yea I agree. That's probably $1k+ for 10hp. But if you're talking about from a stock motor that's a 32hp bump for like, $2k maybe? $2500?

 

Also that's 150 CHP* with the Webers and 160 CHP* with the EFI ITBs. 160 crank gives the 02 the same power to weight as an E36 M3 (US spec) by my calculations...

.075 hp/lbs in the E36 M

.074 hp/lbs in the '02

 

...or the same as dropping in a stock M20

 

Edited August 7, 2018 by Mucci

[jrhone]

1 minute ago, Mucci said:

 

Yea I agree. That's probably $1k+ for 10hp. But if you're talking about from a stock motor that's a 32hp bump for like, $2k maybe? $2500?

 

Also that's 150 CHP* with the Webers and 160 CHP* with the EFI ITBs. 160 crank gives the 02 the same power to weight as an E36 M3 (US spec) by my calculations...

.075 hp/lbs in the E36 M

.074 hp/lbs in the '02.

 

 

$1k?  Triple that.  Haltech System with ITBs are $2k for parts.  Not including labor or tuning....If you have a bone stock motor, you need to go with high compression pistons, cam, exhaust...Thats probably about $2k minimum, but more like $4k for motor work, and $3k for the EFI system..that will get you to 150-160hp...

 

Power isn't cheap...

 

The beauty of EFi is the tunability and power delivery.  It also can start you down the Turbo path....

 

 

[Simeon]

A properly set up fuel injection system is only going to find the HP that is lost by a carb / distributor set up. A stock engine isn’t going to be lacking that much fuel and air. A carb and distributor could be set up to give you the same max power, though noting that you may well be losing HP at different engine speeds and loads. The ability to fine tune an engine management system means that you lose less power under other driving conditions so the main benefits are in terms of drivability and responsiveness. 

 

With stock compression and camshaft, I would imagine 10HP increase in peak power to be about right. 

[Schnellvintage]

+1 I agree, with all that has been said prior.  There are other benefits that some people need to be aware of before the "10 HP" gain should be dismissed for the cost.  The ability for EFI to adapt to all ambient temperatures, altitude and other driving conditions may be worth the cost over the single/multiple carb setup.  Max HP is not always the end all be all for some.  Mileage is also gained over a Carb setup with a benefit of more HP.  I enjoy these cars more when they are easier to start and drive. EFI can be made quieter with more HP.  It all boils down to personal preference and drivability, I guess.  My engine produced 128HP/133 Lbs/Ft at 5800 RPM at the rear wheels on a chassis dyno, in addition gets 30+  MPG on the hwy.

fwiw

Matt

[Mucci]

17 hours ago, jrhone said:

 

$1k?  Triple that.  Haltech System with ITBs are $2k for parts.  Not including labor or tuning....If you have a bone stock motor, you need to go with high compression pistons, cam, exhaust...Thats probably about $2k minimum, but more like $4k for motor work, and $3k for the EFI system..that will get you to 150-160hp...

 

Power isn't cheap...

 

The beauty of EFi is the tunability and power delivery.  It also can start you down the Turbo path....

 

 

 

My point was it was a 10hp gain on a motor that already had a bunch of money thrown at it, and that it was really more like a 30hp gain for that money if you're starting from a stock engine  (I.e. 100hp)

 

I do my own motor and fabrication work aside from the machining so I guess we're coming at it from a difference perspective. That Haltec kit above includes almost everything for the $1500. That can be done for a lot less with a motorcycle throttle body bank. The Haltec Elite 550 they use is $430 with harness. A set of Hyabusa throttle bodies with injectors can be had for around $60-80 on eBay. Dyno tuning is around $200/hr. I realize there are a lot more peripherals to the system but buying a bolt on kit isn't the most economic. Sure if you farm it all out you'll pay through the nose but it can definitely be done for less than $3k if you do a lot of the work yourself and are smart about assembling the parts needed. Paying "$7k" for 160hp just doesn't make sense to me. 

Edited August 8, 2018 by Mucci

[dbmw2002]

Hmmmmm, Anybody down for a a 77-78 320i mechanical injection conversion on a o2? I know it made my o2 engine wail like a 10$ date on qualudes when a stock o2 engine I installed it in my 320. Never had a stronger m10 engine at my right foot. Just couldn't smog it, yes I love California. Has anyone ever tried this? Very doable to a o2? Seriously?

[Simeon]

1 hour ago, dbmw2002 said:

Hmmmmm, Anybody down for a a 77-78 320i mechanical injection conversion on a o2? I know it made my o2 engine wail like a 10$ date on qualudes when a stock o2 engine I installed it in my 320. Never had a stronger m10 engine at my right foot. Just couldn't smog it, yes I love California. Has anyone ever tried this? Very doable to a o2? Seriously?

 

The CIS system? I have had a couple of cars with it (a Saab turbo and a 280 TE MB) and it proved reliable but not outstanding. Not sure it would be worth the problems to fit. Aren’t the injectors plumbed into ports in the cylinder head directly into the inlet tracts on the M10?

[AustrianVespaGuy]

Just one mans opinion of course, but I view the CIS system as the crudest of OE fuel injection systems, but also the absolute idea candidate for an EFI upgrade.  CIS meters fuel based on intake airflow, and the airflow is measured with this giant rudimentary flapper 'lever' that sits in the middle of the intake air stream and get's 'lifted' as more air flows by it:

Yes, your engine is trying to suck all its breathing air past that giant thing, complete with all the linkage adjustments.  The Egyptians would have thought it crude.

 

However take all that crap off, press in new injector bungs (while still using the factor fuel pump, rail, and pressure regulator) use a MAP or TPS sensor for engine load instead, and presto, proper modern EFI!

 

Sure, CIS was fine back in the dark ages of the late 70s when emissions regulations were choking the life out of IC engines and you compare it to equally barbaric solutions such as this:

https://www.allpar.com/mopar/lean-burn.html

(My dad's '78 Dodge Diplomat produced a whopping 140 HP from its 5.2L V8!)

 

But my point is with the options available to us in today's world, I see no place for CIS other than as starting point for an EFI conversion.  And I'll never say a bad word against carburetors, they are very elegant devices that are extremely simple and work extraordinarily well, so I think the OP's question is still the right one, or moreover one of the right questions in a sequence when planning out your car.  Here's how I'd consider the full scope of things:

 

1.) Forced induction or naturally aspirated? (For this thread I'm assuming we're going NA)

2.) Plenum intake or independent runner setup? (For this thread I'm assuming a common plenum setup)

3.) Carb or EFI?

[jimk]

14 hours ago, jrhone said:

Power isn't cheap..

Power numbers don't necessarily make for a good running car.  If you don't mind the coughing, sneezing, stinking, terrible cold operation, high temperature boilover/flooding then carbs are for you.

[TobyB]

Quote

Hmmmmm, Anybody down for a a 77-78 320i mechanical injection conversion on a o2?

 

I'd rather shoot myself in the left... yeah.  No.  Not me.

 

t

 

[Vicleonardo1]

Mucci are you contemplating adapting some Motorcycle throttle bodies for the 02? I believe some may have done that with some Mikuni's ( or was that carbs...?)but I could be mistaken. I would think that would be pretty neat however. 

I have absolutely limited engine knowledge. But wouldn't a lot of the work be creating/adapting the fuel rail, throttle linkage Adding and adapting sensors, the harnesses, adjusting timing, and customizing your ECM while on the dyno? 

I think some would pay for the "kit" to reduce amount of time and effort on their part, which they would be willing to pay for. 

 

Keep us posted on what you decide to do and your results. 

 

I am a guy that can only afford a carburetor right now, but would love the ease and convenience of EFI. 

 

Cheers!