Why old V8's drink more than new V8's?

McobraR · 24-09-2006, 04:31 PM

Just what the title says. My mate (holden fella) was wondering why the old 308 drinks more than the GENIII when they're both pushrods, and, as he says, is basically the same engine (in terms of how it operates etc). He said it cant be injectors cus the VT version of the engine had ecotec injectors (or somethin along those lines).
Would like to hear what people think.

nugget378 · 24-09-2006, 04:38 PM

Its efficiency in the tune,
I wonder if theres much difference at WOT though,or even if its reversed?
It takes fuel to make power.....

Windsor220 · 24-09-2006, 04:39 PM

Gearing plays a big part too. 6 speeds in the Gen 3 help economy.

pks54 · 24-09-2006, 04:39 PM

Head design, efficiency and better response = less movement on the accelerator to get the thing moving.

pks54 · 24-09-2006, 04:40 PM

Quote:

Originally Posted by KJLynx

Gearing plays a big part too. 6 speeds in the Gen 3 help economy.

this too

Barry_v · 24-09-2006, 04:43 PM

they made a deal with the devil for the GenIII... they got power and fuel economy in exchange for sounding *****.

XR8MAD · 24-09-2006, 05:02 PM

All of these plus the computer leaning and riching an enging depending on how U drive it. Something a carby can never do.

Smoked · 24-09-2006, 05:13 PM

Weight of the car?

Falcon Freak · 24-09-2006, 05:23 PM

Carburettor on the old engine versus fuel injection on the new engine. The carburetor delivers fuel in the amount that it thinks the engine requires. The fuel injection delivers fuel in the exact amount the engine actually requires.

FF

Windsor220 · 24-09-2006, 05:24 PM

i think hes referring to injected 308s.

Quadcams · 24-09-2006, 05:30 PM

Quote:

Originally Posted by Falcon Freak

Carburettor on the old engine versus fuel injection on the new engine. The carburetor delivers fuel in the amount that it thinks the engine requires. The fuel injection delivers fuel in the exact amount the engine actually requires.

FF

Spot on no guessing with fuel injection.

Bossxr8 · 24-09-2006, 06:04 PM

The gearing of the LS1's is moonshot compared to the old 5 litre, and they are a more efficient design.

ratter · 24-09-2006, 06:10 PM

The gen 3 is a pretty good engine in desisgn and is a lot more efficient than the 308 but the biggest gain would be the operating system for the EFI. The newer computers operate faster and can do more sampling quicker to fine tune the running of the motor better

SpoolMan · 24-09-2006, 06:24 PM

Quote:

Originally Posted by McobraR

Just what the title says. My mate (holden fella) was wondering why the old 308 drinks more than the GENIII when they're both pushrods, and, as he says, is basically the same engine (in terms of how it operates etc). He said it cant be injectors cus the VT version of the engine had ecotec injectors (or somethin along those lines).
Would like to hear what people think.

EFI and tuning...get your mate to join the blue oval brigade...

:

Lukeyson · 24-09-2006, 07:43 PM

definately tune and gearing as all say, maybe a small weight difference, but the gen 3 wouldnt be that much lighter than the 308 would it ?? 20kg maybe ?

Rollin · 24-09-2006, 07:49 PM

Quote:

i think hes referring to injected 308s.

Holden never made an injected 308 - they dripped capacity to 304 at the same time as they went injected to allow the car to compete in the V8 supercars.

The primary reason the GenIII is so much more efficient than the 5 litre is because the head design encourages a better flame front and a more efficient and complete burn of the fuel in the cylinder, so more energy is extracted from each combustion event than in the earlier design engine.

McobraR · 24-09-2006, 08:03 PM

Yeh i was referring to the fuel injected version. Interesting.... everyone seems to be saying its due to the tune of the engine. Wouldnt that mean that if you tune an injected 308 (or 304 as one stated before) as good as an LS1, then it can drink as efficiently? My mate and i just find it odd how an LS1, which is 5.7L, can drink less than a 5L.

Some people are also saying how the GENIII is a good design.... its pushrods isnt it? what, in the design, is so different when compared to the 308? Im starting to confuse myself here also lol

Sorry just read the last post, so its the head design?... cool! thanks guys!

ratter · 24-09-2006, 08:30 PM

They actually changed to 304 half way through VK and still used carbies on them and also Vl V8's except for the walkies used carbies

XR Martin · 24-09-2006, 08:47 PM

To clarify the head design, it would include spark plug location, injector location, valve angles, valve size, valve material, intake and exhaust port shape, pushrod material, pushrod shape and location, coolant passages. Then theres also piston design, intake/exhaust manifold design,cam design, aluminium block. The LS1 also has a different firing order. (whether than makes a measurable difference to economy is unknown)
Tune as mentioned, GM would have spent millions and millions on it and had thousands working on it compared to only a handful of people Holden would have had working on the original EFI 304 (which came close to be cancelled, since they had trouble finding the money to EFI it)
Then theres other components to aid the tune, all the various sensors, which would be better designed and better located.

BTTB · 24-09-2006, 08:53 PM

I remember reading (when the VN came out) that the
EFI 5L put out less pollution than a 2L VW Flat four !

has to say something about how modern motors burn the fuel more efficiently !

Rollin · 24-09-2006, 09:26 PM

Quote:

Originally Posted by XR6 Martin

To clarify the head design, it would include spark plug location, injector location, valve angles, valve size, valve material, intake and exhaust port shape, pushrod material, pushrod shape and location, coolant passages. Then theres also piston design, intake/exhaust manifold design,cam design, aluminium block. The LS1 also has a different firing order. (whether than makes a measurable difference to economy is unknown)
Tune as mentioned, GM would have spent millions and millions on it and had thousands working on it compared to only a handful of people Holden would have had working on the original EFI 304 (which came close to be cancelled, since they had trouble finding the money to EFI it)
Then theres other components to aid the tune, all the various sensors, which would be better designed and better located.

yeah, wot he said. The physical design of the engine is far superior.

Better designed heads have more even fuel atomisation and distribution meaning no lean spots to create areas in the chamber that are susceptable to pre-ignition.

Also more effective knock sensors and faster more powerful computers, mean the engine can be tuned a lot 'harder' with less chance of killing it.

McobraR · 24-09-2006, 09:39 PM

awesome responses'. thanks heaps!

Pieoter · 24-09-2006, 09:44 PM

Higher compression ratio

McobraR · 24-09-2006, 09:48 PM

Quote:

Originally Posted by Pieoter

Higher compression ratio

That too was one of my 'guessed' reasons in telling him. at least now im not the only one. thnx

bigjim · 24-09-2006, 10:35 PM

Quote:

Originally Posted by Smoked

Weight of the car?

Would have thought that the later commo's (ie with the gen 3) would have been much heavier than say a VP due to all the safety gear and gizmo's, as is the case with fords

XRated · 24-09-2006, 11:33 PM

Interesting thread.

I don't have much knowledge re. V8s, but I was wondering is it possible to make an injected Clevo, for example, utilise an aftermarket ECU and tune it to run as (generally) efficiently as a modern V8 and still make similar power?

XR Martin · 25-09-2006, 01:29 AM

There is the odd EFI clevo out there. Biggest issue with them is getting a EFI intake manifold for them, which I dont think are that common, or cheap.

**ebxr8240** · 25-09-2006, 10:28 AM

Yes the Carb inlet can be adapted with 90* pipe on carb flange & throttle body attached, but the short runners leads to hiigh rpm torque compared to longer efi type ...I know why mine goes through more fuel how ever!!!

nugget378 · 25-09-2006, 10:46 AM

Quote:

Originally Posted by XR6 Martin

There is the odd EFI clevo out there. Biggest issue with them is getting a EFI intake manifold for them, which I dont think are that common, or cheap.

Its not that hard actually,a manifold like a TFC or CHI can be drilled for injectors (the bosses are already there on some) and a throttle body bolted to the top.
The big cost is in the ECU,fuel system,TB,and tuning...