I am considering using EFI (either Delco, or more likely Microtech) on my next engine. I will use two IDF-style TBs, Commodore/Bosch injectors with a Weber-style linkage... does anyone have ideas where I can start looking for TBs?

[Edited on 20-10-2004 by VWCOOL]

Here is a start!

There are some good links from these sites as well. From what I've learnt about EFI the single throttle body design is better for tune-ability. quad throttle bodies do work, but better vacuum signals with single TB and plenum.

http://www.cevw.com/ 

http://www.carburetion.com/index.htm 

http://www.injectionperfection.com/ 

http://www.jenvey.co.uk/ 

http://www.kinsler.com/ 

http://www.sandrail.com/millerfi/ 

http://www.redlineweber.com/ 

http://www.speed-technology.com/ 

http://carcraftinc.com/turbo.htm 

thanks for that. I'm investigating a remote-mounted IAC pumbed to the two IDF throttle bodies - all GM (probably Camira) stuff tuned using Kalmaker on a double-plugger. Would prefer dual TBs rather than one for airflow/power... although I do have a Camira/Bosch TB here I could play with... I think it's about 60mm... The cam I will use (I think you know from who...) gives good steady idle vacuum.

[Edited on 20-10-2004 by VWCOOL]

It has been said that this intake design is pretty close to ideal.


The price is a killer though. Far cheaper to calculate the figures and design your own.

Have a look at the Suzuki Hyabusa TBs. They are flanged the same as Webers (IDFs I think) A mate has a set on his Alfa powered hot rod. They generally come with injectors and perform well. Not sure of throttle size ? Check ebay for secondhand ones.

Glenn

Vintage has some IDA throttle bodies 50mm available

Thanks Dave, but I want to run IDF style as the manifolds are straighter and work better, IMO

Quote:

Originally posted by 56astro It has been said that this intake design is pretty close to ideal. The price is a killer though. Far cheaper to calculate the figures and design your own.

This is what an FI guru on STF wrote about this set-up:

lol... yeah, 'conducive' and 'knuckles of turbluence'... :blah Stuff that s*it! If they'd designed it properly, they wouldn't HAVE 'knuckles of turbulence!!! Thanks for the pic, Astro, but for a variety of reasons I have to say that is WAAY off a good design... it's a pile of parts!

[Edited on 21-10-2004 by VWCOOL]

I agree, that design is not conducive to good air flow from TB to valves.

Because of the design of the flat-4 any single TB induction system will be compromise.

I like the std VW twin port FI castings that CB sell, but not sure of the internal dia. If they made a similar one without 1-into-2 at the end, I think they would be real winner.

Designing a plenum for a straight 4-6 or V6-8 engine is going to be easy compared to one for a v-dub. But still, even the WRX STi still has a plenum system in preference to individual throttle bodies.

What's the engine going into?

The engine is a new one for my Beetle - Oval/IRS etc etc

Hey guys,
I have an subaru EJ25 in my buggy.
At the mo I am thinking about how to get it ready for the drags.
It is the dohc motor, so the heads flow big standard so i am told. It puts out 165hp standard. I am looking for around 225hp.

before anyone suggests it, I am not interested in a turbo.
1. the car has to be street registered (keeping wife happy) and it can't be with a turbo with that much capacity.
2. I want to run all motor class and that means no turbo and no nitrous.

What i am trying to figure out is whether to go to quad throttle bodies (big $$$) or stay with the standard intake manifold. Guys in the states say it is very efficient, but surely 4 throttle bodies would be better? I know it would need a plenum, but I will figure that later.

Any thoughts?

nah, for WOT plenum and TBs don't matter. Plant 'n go! I'm looking for crisp, on-street and on-track throttle response

WHATS "WOT"?

I think "waste of time"

ryan here on danielles nick,

just onto the quad TB vs. single, the quads will give more response as they will be near the ports etc.
and with any decent aftermarket ECU, the load input should be able to be set to work off throttle position rather than MAP.

they do this alot when injecting non turbo big ported rotors, as they have a very erratic vacuum signal at idle.

any ideas for a factory set of TBs I could adapt, or would I need to buy aftermarket jobbies?

WOT = Wide Open Throttle

Something that I noticed whilst doing the research for my EFI system (Delco/Kalmaker with JE Camira components) is that the factory VW EFI on the Type I engine does not use a Plenum chamber.

It is generally accepted that Plenum chambers are used to dampen pulses in the intake vacuum at low revs/idle. This helps to stabalise the MAP signal to the ECU. Some of the aftermarket ECU's can be told to ignore the MAP signal at certain revs, effectivly making a plenum chamber unnecessary.

I haven't used a plenum chamber on my system, so all I had to do was desensitise the acceleration and deceleration enrichment (triggered by changes in the vac signal) and all it all worked using a MAP sensor right down to an idle. I could have also made the ECU ignore the MAP signal at an idle, but the manufacturers of my ECU reckon that you almost need a V8 supercar spec cam to warrent doing this!

Of course, if you do decided to go with twin TB's, you will still have the issue of unbalanced linkages, just like you do with twin carbs....

Make sure that the TB's are not too big, as this can cause the engine to have a 'boggy' feel to it when you open the throttle. One of my friends is currently running a TB from a 4.0 litre Falcon on his Microtec injected 2 litre type III, and it suffers from this issue. He is just about to change the TB to one from a Hyundai or similar vehicle to see if this is the only cause of this problem...should know soon. Exactly how to define 'too big' is a tricky one though!

Connecting the IAC and MAP sensor on twin TB's is not a problem. The map sensor is connected by running a balance hose between the TB's and fitting the MAP sensor in the middle.

Of course, twin TB's look great! I would still attempt to fit a single air cleaner to the system though, as I have read plenty of times that this helps throttle response too....

....I just thought of something, when running twin TB's, could you run the balance hose from each of the TB's to a sealed box, then run the MAP sensor from that box. The box would act like a Plenum Chamber wouldn't it? Might help someone out if they are having problems where vac signal fluctuation is causing problems on a twin TB set-up....

Just make sure that you ECU can do everything that you are likely to need it to do - this will be your limitation....

R

could you post a pic of your setup?

what ECU are you running?

...yep, I'll have to go and take a decent pic first though! Anything in particular that you would like to see?

I'm running the Delco 808 ECU (from a JE Camira/VP Commodore/VN Commodore/N13 Astra/N13 Pulsar) that has had the Real Time board fitted by the guys at Injection Connection in Perth. Have a look at their Web site: http://www.kalmaker.com.au if you are interested in the ECU and software....

R

BTW, how critical is the distance between the ports and the TB?

coz I was thinking, if you could bring the induction tubes across the top of the motor and put the TBs right next to each other, you might be able to solve the whole "linkage going out of adjustment so often" issue.

Didn't Lee Harris (dark green 58) have efi with quad TBs on his motor?
is he on the forum?

the distance between the TB's and the ports is not all that important as far as I can tell (from the info that I have read). If you were going to go to the bother of mounting Twin TB's side by side, to eliminate the linkage problem, you may as well just use a bigger single TB.

Remember that size of the intake manifold is not a important on an EFI system as it is on a Carbed car as you are only drawing air through the manifold, not a fuel mix.

I have used a standard 1600 TP manifold center, with modified 1600 TP end castings (modified to hold the injectors), and an adaptor to allow me to bolt the TB on to the manifold center....perhaps not the ultimalte way of doing things, but it definatly works!

I have to go to work now.... I'll be back later!

R

The distance between throttle plate and port is very important. Having a short distance between the throttle and the ports gives the best throttle response, especially with no plenum - that way, the atmosphere pressure can fill your cylinders as soon as the throttle is cracked open, not have to blow air through a long twisty messy labyrinth of pipes and chambers. Instant fill = instant throttle response and better power (less loss through intake system). That's why many higher-performance cars have multiple throttle bodies

MAP (manifold actual pressure) on my planned management system/Beetle will be sensed from a remote 'vacuum chamber' ported to each throttle body... I will possibly mount the IAC (idle air control) valve to this remote chamber, too. I have seen this doen before with success on 8TB V8s etc but there is teh risk of the IAC affecting the MAP if both are plumbed to the one chamber - they may have to be independent to help 'dampen' vacuum pulses. For thsi reason, I may possibly use TPS (throttle position sensing) for my idle control if the MAP method doesn't work... not sure yet....

[Edited on 22-10-2004 by VWCOOL]

[Edited on 22-10-2004 by VWCOOL]

Here’s a different theory: www.dune-buggy.com/turbo/intake.htm

lol... thanks for the link, but with terms like 'expandable air', I didn't bother reading past the first sentence...

[Edited on 22-10-2004 by VWCOOL]