CARBURETION and your Large/Small port 16V 4AG

[BenR]

Tada! correct.

But if you dont disconnect the sensors such as air temp, coolant temp, TPS and map then you will have a fully functioning 3d ignition map.

Seriosly guys, your making such a simple task into such a hard one.

[Apolan]

Hi guys!

A good deal on a couple of delorto dhla 40ies has sucked me into carbing subject 2 days ago. Since i was planning to try this some day anyway, why not now when im rebuilding the engine. So for the past two days i did alot of reading on the subject. Please help me out abit here..

So the carbs are delortos dhla 40. I have a bigport map engine. Jetting is pretty well explained in the club4ag reference section. Also im quite well acquainted with wiring it up so it could use the stock ecu. But today i've been reading some old topics on this board regarding carbs, NoHachi mentioned that using the stock ecu in the limp home mode hinders the max potential by at least 20%. Does wireing up the map sensor like explained above (firehawk, Ben) improve on that? Im not quite sure how this 3d map works..

My goal is to make an efficient engine with carbs, not something that would run on half its potential, and drink more fuel than a wrc car.. Can this be done with the stock ecu?

Also i would like a ballpark figure from you guys in terms of horse power and fuel consumption when using carbs. I'm imagining carbs + polished head (have read bens topic on that too) + maybe a better header. Is it irrealistic to expect 140-150 hp with solid torque from cca 3500 up from that alone? and 10l/100km consumption (when driving nicely)??

Thanks!
saso

[firehawk]

Apolan Wrote:NoHachi mentioned that using the stock ecu in the limp home mode hinders the max potential by at least 20%. Does wireing up the map sensor like explained above (firehawk, Ben) improve on that? Im not quite sure how this 3d map works..

For a street driven car, using locked ignition advance in limp mode is certainly a bad idea and would make the car reluctant to start and probably quite annoying to drive in city. Faking the missing sensors using resistors as I described above would make the ignition work just like it does on a stock engine - with one exception, though. The IDL switch inside the throttle position sensor would still not be functional, so the ECU would never go to the idle/overrun "map" - this might create a need to raise the idle speed a bit and also cause some popping in the exhaust when engine braking.

Do the Dellorto carbs have ports for drawing manifold vacuum or would they also need the vacuum to be tapped directly from the manifold runners? My TRD manifold has threaded holes only to runners 1 and 4 so I've been thinking whether it would be possible to take the MAP vacuum signal from these two only and maybe use a small filter/restrictor in the hose before the MAP sensor to even out the "bumps" a bit. I'd rather not butcher the manifold by drilling additional holes to it.

[jamiemirror]

About drilling for vacuum signal - 4AGE injectors are mounted on the head instead of manifold. You can use their holes to get vac. signal.

[firehawk]

That's, true - yes. One could actually use the fuel rail as the vacuum reservoir by making "dummy injectors" with o-ring grooves in a lathe. The holes on the rail could be used for the brake booster and MAP sensor. A really simple and elegant solution.

Unfortunately, I've already made brass plugs for the injector holes and they are interference fitted to the head.

[Apolan]

Wow i never thought of that, seems like a very nice solution indeed.

Now just to be sure, would this system, with a nicely ported head and a better exhaust (header) be a solid and efficient performer for street, occasional track? Looking for stable reving engine 140-150hp, that i could still do a "comfortable" 10l/100kms on street. Is this possible, please let me know. I dont mind having a bit higher idle.. Or would this setub be just no good for daily driven vehicle?

Thank you for your replys

[jamiemirror]

The problem Apolan is that you will find answers in your local tunning company. We can say "yes" or "no" but it depends on tunning.
IMHO yes, this is possible (and normal to expect).

[Apolan]

great, just want to make sure im not deluding myself. The man who would do the job is a motorcycle and porsche mechanic.. i guess he knows his way around carbs

so guess im calling the guy tommorow.. thnx for the answers.

[jap-si]

hmm i have some thinking to do, now quite woried about how quick this can be done. didn't expect this amount of problems. thought the timing stuff sorted it out.

i have the engine rebuilt at the moment but only have 5 days to get the ignition in and set up and rolling. if not it is off the road for 3 weeks.


if anyone can advise on what to do with the kit i have it would be greatly appreciated.












i think i need to sort out a brake booster but that should be easy to put in.

[jamiemirror]

You can get carburator setup info from here:
http://www.club4ag.com/faq%20and%20tech_...04A-GE.htm

Use some kind of vacuum accumulator in order to get stable vac. "signal". You can use 4AGE injector holes to get the vacuum, join 4 tubes to one canister (for example 30-35 sm long/1-2sm diameter) and get the vaccum from that canister.
Try to run on fixed 20 or 25 advance if you have no other option with the MSD.