Want to EFI my L28 260Z

[Nizm0Zed]

Ok, i managed to score a V2.2 Megasquirt for $180 (au) which is incredibly cheap (normally around the $600 mark prebuilt around here), so thats in my hot little hands now.

 

i was thinking about using the stock L28 manifold, but as has been stated many times before, they flow like crap.

So, custom is the flavour of the day.

 

My Biggest problem is the car MUST be daily driven.

Yea, i know, thats a tough one.

current engine in the car is a L28 block, with flat tops, and N42 head

 

So, i have 2 ideas.

(feel free to shoot holes in them)

 

Idea 1.

remove the SU's and spacers, and replace the spacers with a piece of alloy, thick enough to mount 2 injectors in it, then bolt the SU's back on.

so a total of 4 injectors. I have injectors big enough (just) to do this allready. (i did think about mounting the injectors inside gutted SU's, but cant make them fit)

I can retain the SU's for daily driving when i need to, and switch to the EFI for tuning till its all set properly, then remove the SU's and replace with a throttle body, most likely the throttle body off a CA18 engine in place of each carb.

I have a rather plentiful supply of them, and they have a 50mm butterfly on them.

 

Idea 2.

Weld on injector bungs to the standard carb manifold, and set the injectors up as multiport injection. Using the same injectors as before, but 6 of them, they will be more that adequate. (From a straight 6, 4.0L engine)

Same as before, keep the carbs in place, and switch to EFI for tuning.

Once done, replace the carbs with throttle bodies.

 

For the fuel system, id mount a EFI pump and surge tank in the engine bay, yes i know, not the best place, but for the setup and tuning, i can feed the facet pump into it to keep it full, and return all the fuel form the rail into it, shouldn't starve out the engine at all, when its all set up, I'll move it to the back.

Ignition system will be individual coils, allready building the crank trigger.

Changing over between carbs and EFi, would merely be a case of re routing the fuel line from the facet pump to the surge tank, and changing some HT leads.

 

 

Ideally, i would like to build an individual throttle body manifold, one throttle in each runner. And i was thinking about using the throttle plates (Or whole body) out of the CA18, but with a butterfly at 50mm, would it be too big for 6 of them? wouldn't have any problems with flow.

Should have a theoretical surface area of 11778mm'2 with 6 of them. (i think my maths is right?)

would that make the engine bog down in low rpm?

I guess if i go with option 2, at least then i allready have the fuel system set up and tuned to swap straight over to the 6 throttle manifold, just need to tweak the mixtures for the extra flow.

i was also thinking that maybe i could position the injectors inside the plenum, pointing right down the runners, straight at the throttle plates.

If i could get the engine to rev, and flow all the air, it would potentially make some serious top end power.

 

Ideas? thoughts? opinions?

all criticism welcome.

 

Alan.

[Daeron]

I like the idea of the SU manifold used with twin TBs; http://forums.hybridz.org/showthread.php?t=124201&highlight=manifold for more on another project with that in mind. 2nd gen 300ZXs used a twin throttle system that might be useful to scavenge for the cable linkage and maybe parts to link the two throttle drums. I don't quite understand the point of retaining the SU's as carburetors in any case, but that is personal preference as much as anything else.

 

Route the fuel return back to the main tank, not the surge tank; this will dump the fuel already warmed by being in the fuel rail back into the tank, and avoid storing it up in your surge tank.

 

Z-ya, in his project, simply cut off and welded a stock EFI manifold's flange onto the SU manifold runners; I am not sure of the benefits or advantages of staying with a two piece SU manifold or welding it into a single piece with the stock mani's flange on it, but it saves placing the bungs in the SU manifold.

 

I am very very interested in this build idea.. Z-ya and I started thinking about it virtually simultaneously, and independently (although I DO suspect we may have been stimulated by a few of the same comments on this board) but he has actually done one, and I sit on my behind, Good luck!!!

[Nizm0Zed]

thanks for the link, yea i will eventually route the fuel return directly to the tank, but having the surge tank in the bay, and keeping the SU's fitted keeps it driveable as a daily, while still allowing me to easily switch over for tuning, and not be stuck walking 40kms to work.

 

also, by keeping the carbs in place, for the initial setup and tuning of the EFI, it also retains their throttle system, and works just like an EFI throttle body.

 

I even considered converting to straight gas (LPG, we call it gas down under) and running LPG injectors inside the SU's, they are much more compact, and i could hide the whole system.

EFI type driveability (and can be boosted through the SU's) with an average 110 octane fuel for about 70 cents (au) a litre.

unfortunately there is about $4000 worth of conversion costs, AND id need to build a high comp 11-12:1 ratio engine to make the most of it.

[Daeron]

are you my freaking brother? LPG powered Z car has been a dream of mine since I was thirteen

[Nizm0Zed]

What? LPG isnt a common thing over there??

 

We have a pretty large amount of cars running LPG over here, pretty much all taxis, and a LOT of couriers are all dual fuel cars.

 

dedicated LPG isnt as common though, strangely enough.

[Daeron]

nope. when I was 13 I met a guy who had an early 80's chevy conversion van that ran exclusively on LPG ("carbed" of course)... and to the best of my knowledge thats the only vehicle I have ever seen that ran on it.

 

I search and search for information that would help convince me that I can put together an L-series that runs exclusively on propane, in a high performance, "efi" type application (as opposed to a simple venturi "carb" type setup) but I cannot find the info I want.. In case it needs to be said, I am thinking about high compression, forced induction, to take advantage of that octane rating. OR, maybe simply pushing the high comp NA envelope on the street.. but those specifics are fuzzy to say the least.

 

I know it has to be do-able, and when I get into THAT point I may just have to blaze my own path.. but I want to learn what I can now and am totally surprised at how many websites I have looked at that made me believe it was possible, BUT were only selling complete kits for specific engines, and didn't have any info that would help the un-indoctrinated do-it-yourselfer.

 

I have FAR bigger fish to fry, but this is my favorite pipe-dream, and it makes sense in so many ways that I cannot believe it is out of my reach entirely.

 

/hijack off

[Nizm0Zed]

wow, we are getting off track arent we.

 

anyways, heres a few links for you.

http://www.gas-injection.com/

http://www.alternatech.co.uk/products.html

http://buy.ecplaza.net/search/3s1nf20sell/lpg_injector.html

http://www.keihin-corp.co.jp/english/products/4wheel/index.html

http://www.gasresearch.com.au/

 

I seemed to get better results from google by using "LPG injectors" Instead of "LPG Injection"