briannutter

The dome is like a pyramid that's lopped off at about .400" tall and has what I'll call a sugar scoop facing the injector. The Injector fires into the scoop at about 2200psi (I believe) for atomization. The dome is heavily radiused from the factory and hard to replicate without 3d dome milling...which is time consuming...so we've developed special form tooling to really do it right.

A buddy of mine, baldturbofreak in New York, has a solstice GXP that he's playing with. 80 ft. lbs with a conservative reflash. The aftermarket programmers are unlocking more pages all the time. The window for injection is very short and timing the pulse is crucial. The main issue is the tuning window becomes shorter and shorter with increased rpm. Porsche made the statement last year that one of their new engines is the first to hit over 10k rpm with DI.

Sbertolone

iTrader: (5)

so basically its very similar to a diesel piston in terms of face profile.

briannutter

well, not really. Most diesel pistons I've seen are flat with a "spike" in the center with the highest point being below the deck of the piston. There's a deep "moat" around that. I've attached a pic of a DI piston on the right. Similar to some of the others I've seen.

Lickeyman

iTrader: (1)

Yeah and Toyota pays their line workers like 17.

That's why they make the money. I understand unions and all but it does ZERO good if the companies can't compete. And GM sells alot of cars. GM should be well in the black with the sheer number of vehicles they produce.

gectek

iTrader: (2)

Yah, as for diesels...the reason they run high CR is due to the compression ignition factor. They run a "ricardo cup" in the piston, because they piston is the chamber. The heads are flat. Gasoline engines need quench to help...diesels dont. They are a mass of detonation, they dont care.

#2 since when have you seen an engine go from PFI(port fuel injected) to DI to claim this 50-100 HP difference. I have seen one instance on an audi engine....a 1.8L. It made about 1-3 more HP at a peak but everything was pretty much the same. They create more cyl heat, not cooled, sorry...the higher compression is usually needed to burn the highly lean mixture. They produce worse NOx emissions. so how are they more efficient? Plus fuel economy is worse also.

#3 on a non direct injected diesel, they have made more HP than in a DI. They have a small prechamber in the head(like on a 6.2/6.5) that takes the diesel, then it burns from there. But they didnt produce alot of power because they were low on boost and too high on the CR at the time. When they upped the boost to 17is PSi and turned the CR down a couple points they made more than the DI of the mighty 5.9l cumming and the powerchoke too.

There also wouldnt be a DI "kit" because that would mean brand new/redesigned heads that really have no room for anything else in them, and a high pressure normally mechanically driven (ie the new caddy rattle trap) pressure pump. Does anyone realize how much money that would really cost?

Also, that is how diesel guys get so much more power from a stock engine. they turn up the inj pump. a few guys have successfully cut through pistons with enough pressure. some have left spray patterns in them from the atomized fuel hitting it.

It would be a novel idea IF infact all that has been said on here would actually happen. It wont. Sorry. Esp with CARB and cali holding the reigns and not a single domestic car company having any money to pay the ceo's so they have to work for a $1 (thats another story).

Sbertolone

iTrader: (5)

thanks this was what i was looking for.

briannutter

#2 since when have you seen an engine go from PFI(port fuel injected) to DI to claim this 50-100 HP difference. I have seen one instance on an audi engine....a 1.8L. It made about 1-3 more HP at a peak but everything was pretty much the same. They create more cyl heat, not cooled, sorry...the higher compression is usually needed to burn the highly lean mixture. They produce worse NOx emissions. so how are they more efficient? Plus fuel economy is worse also.



I don't think the statement above is true at all. First of all, every DI engine I've seen is clean sheet of paper in terms of the top end...there isn't a comparison (good or bad) to a conventional engine. 2nd...timing the fuel to enter ONLY when it needs to be there is what allows a serious bump in compression. It reduces emissions and increases mileage because fuel is being injected at precisely the right moment for burn rather than going out the tailpipe. Turbo engines are taking advantage of this too with higher static compression allowing for good power even off boost. As for heat, well horsepower is heat...the more the better. DI is a GOOD thing...not a bad thing...it's just going to take us a while to learn how to tune it.

gectek

iTrader: (2)

Im not thinking on this one....this is first hand knowledge. sorry. by reducing emissions you mean its running leaner(NOX CO, CO2) then i thnk you are mistaken. im not saying DI is a bad thing, its just not the end all be all of the auto world. just like hybrids arent and flex fuel isnt. all hype.

briannutter

"leaner" yes-up to 65:1 ratio, but only at certain low load times like deceleration. We've got a few things here that help. A: Much finer droplets of fuel both from rail PSI and hitting the bowl at the last stage of the compression stroke....finer atomization means quicker and more complete fire in a shorter amount of time B: You're reducing cylinder wall wetting under many conditions making for better ring life and less oil dilution. C: Throttle changes don't require "accelerator pump" action. Some of these DI engines are tuned to not require a throttle plate..so you're not getting pumping losses from that. D: The intake ports now flow AIR instead of 12 to 15:1 air/fuel....more CFM per any given cross section equals more oxygen to burn the fuel.

True enough, During cruising moderate loads, it goes into stoich mode and in full power, it will actually advances the pulse window to start on the intake stroke like normal.

If you do want to compare a couple engines...use the 3.6 Caddy. Non direct injection makes 263hp versus 304 for the di. Torque goes from 253 to 274.. EPA MPG goes up by 1 with DI and the octane requirement lowers to 87 for cheaper prices at the pump.

The Alchemist

iTrader: (19)

That's what my motivation was for putting up this thread to begin with. More power, more torque, better fuel mileage (hey every mile counts, especialy with CAFE standards) all on lower octane gas.

So on a 3.6L motor, you see 41hp and 21 ft/lbs so what would you expect to see from another 2 cylinders???? 50hp? 30ft/lbs? I can buy that.

AdioSS

iTrader: (2)

The V6 makes 304hp, that is 50 & 2/3 hp and 45.5tq per cylinder.

A V8 version would be 4.8L. Assuming the same specific output (not compensating for the additional friction), it could make 405hp and 364tq.

Increase the displacement to 6.0L and with the same assumptions we are looking at 507hp and 455tq. Bump that up to the LS7's 7.0L displacement and you are looking at 591hp and 531tq.

Just imagine a direct injection LS9...

tittan1500

iTrader: (8)

also by running DI your cylinder heads will be able to get more air into the chamber due to the lower viscosity of the air charge which increases the remolds number

deadhorse66

iTrader: (2)

GM estimates as much as 65% in that time frame. Saw that in our tech link last month.

GM_USER

Not only more air though. The thing is with DI is that the pulse is right at combustion point. You could run INSANE compression with that! Think about it, the only reason that we can't run high compression is that we are mixing the air and fuel so that it comes into the chamber together. Too much compression and you get knock. That is why octane is added to prevent the burn until optimal conditions.

Take the fuel out till optimum conditions and you can't have any knock! The only way you could is residual fuel not burning. That is why DI is awesome.

The thing about it is that GM seems to be using this principle too. That 3.6 has an amazing gain and that is probably a safe CR and tune on it.

Just switching to DI won't help if you don't go with a lot of compression and a good tune.

pmbmax

I have a ? for you How many people worked for Toyota say 30 to 35 years ago . How many did the big 3 have working for them. The big 3 sale less cars because of the others taking part of the market but those people are still drawing retirment. Toyota , Nissan not in buisiness as long so their insurance and retirment are not as much of the pie from each sale. I am union and trust me "the man" would pay you dog **** and rat meat if it was not for the UNION . I like making good money