Efi & Turbo Issues...

[Woz]

well, ive been reading all these posts saying that efi will do wonders for economy and drivability etc. but wont give you shitloads more power.

but whats the story when you go efi + turbo?

wouldnt this allow you to have a perfectly tuned engine nearly always? ive heard people having big problems tuning turbo carby setups... and have had to resort to efi. wont a properly setup efi turbo system be able to get far more psi without the risk of detonation unlike a carbied engine? whatabout even having the maximum boost worked out from how hot the intake air is, to avoid detination?? how about being able to drive your car on 7psi on weekdays and 14psi on weekends??

wouldnt this shit all over a carbied turbo setup?????

just a thought.

woz.

[martin]

not much use to your particular question but after driving my first gem which was a carbied 1800, to my new one which is stock 1800 EFI it dosn't make a whole lot of difference power wise. The latter has a bit more grunt, yeah, but not a whole lot. The biggest change has been economy. I could only get 350 to 400k's out of my old gem driven mostly grandma style with a few drags here and there, but with the new one with the same size fuel tank i can get closer to 500.

so economy wise, on the gemini at least, efi seems to make a pretty good difference, performance wise i couldn't tell you but my guess would be it would be much easier to tweak an EFI turbo than a carby

[Fastgem]

It wont really let you run a lot more boost at that comes more under turbo efficiency, intake temps, cylinder pressure etc but yeah its going to make a lot if difference in drivability and especially fuel economy eg it only needs to deliver a little bit of fuel to the engine when the cars off boost then a whole lot more when the turbo kicks it compared to my twin carb set up which just delivers a shit load of fuel to the engine all the time.

The only real draw back to efi is the initial set up cost. You need high pressure fuel pumps, surge tank, manifold, injectors, computer, maps, sensors, plumbing etc A good computer can cost around $1300 and then about another $300 on that just to have mapped, but once its all running then yeah, it rocks.

[PiNk_Tx_CoOp]

Hey,
I got a EFI manifold and dizzy sitting in my gagrage if anyone is interested.
Put a G200 in, but it ran out of funds to convert to EFI.
Make an offer

[Ben Wight]

What a question!

For starters, I dont believe EFI will give more power over a poperly sized carby setup in a WOT application such as drag racing. Many teams have proven this.

EFI has benefits in many areas, mainly tunability over a wide operating range, assuming you have a tunable computer. A factory computer, and you have shit all tunability. You can get gadets, and hook up bleeds from sensors, etc, but they are not the best solutions.

My carby turbo setup for example cruises on the highway at full rich, I think mainly because the idle and main circuits that I have are in a much larger carby than I would consider for normal use on a NA engine of my capacity, but for maxiumum power, it kicks ass. An efi system on the other hand, can be leaned out when the engine is not under load much more easily than a carb, believe me, i've tried. So there is one beneift. Better highway fuel efficiency.

Another benefit is the lack of sealing issues relative to a blow through carby application. The gasket seperating the fuel bowl and carb itself is critical in a blow through application, as any leaks can lean the mixture out and casue detonation. This problem is virtually eliminated with an efi system, but a carby system can be made to work very sucessfully. Carbys tend to have troubles with boost pressures in the low 20's and higher, I have had mine to 20 with no worries, but I have had troubles before at much lower boost pressures.

Generally speaking though, a carb can go to around 20psi safely, even though most efi cars dont go above this boundary anyway.

Most efi computers dont work out the max boost being able to be run with respect to inlet charge temps. Only some exotic cars such as audis do this, actaully most cars with electronic boost control would do this, but most cars do not have electronic boost control. Even most aftermarket computers dont have a feature of boost reduction with respect to inlet temps. This is pointless anyway, a knock sensor is a better indication of wheter boost should be reduced.

Any turbo kit in the world can be swapped from 14 to 7 psi and back without needing efi. I do this at the moment, from 14 to 18. A carb is designed to meter fuel relative to the amount of air that is being consumed by the engine, jsut like an efi system. Going from 7 to 14psi boost is just like chaning engine speed from 2500rpm to 5000rpm. One carby does it all!

But EFI does have its benefits, its safer with respect to leanouts, its better throughout the rev range with respect to mixtures and the manifold designs are much better at equal mixture distribution, one of the main benefits. The down side is its cost. its a lot of money, but better insuarnce against broken egnines, a low boost, low power system and I would go carby all the way. Efi is simply not needed.

Ben Wight

[Bugle]

EFI costs more to setup, but in the long run you'd save money by not having to pay for heaps more fuel