Forced induction and carbs?

[bnicho]

Weber bought out a downdraught carby for blow-through Turbo applications - the 34DMTT. It shares the same bolt pattern as the DGV etc, but they are pretty hard to find. You can still run an intercooler, but as already said, it must be before the carby.

Hope this helps,

[The Witzl]

the carby vs EFi argument is by far the stupidest and oldest argument i've seen on these forums....

I doubt there is a SINGLE person who has asked/argued the question on these forums who would actually benefit from a carburettor system as opposed to an EFI system on their personal vehicle.


When you are talking pro-stock engines, you are talking about US$90,000 worth of engine.
That's hardly a fucking 2T or 4A-GE now is it????

It's like comparing chocolate and shit.



And whilst im at it - here's some REAL WORLD comparison that's appropriate to most people here..... my previous 18R-G.
Dyno w/stock Solex carbies: 68rwkW
Dyno w/stock EFI system: 73rwkW
..... that is the EXACT same engine, remove carbies and put on EFI. That's a change from two 40mm Mikuni Solex carbs (essentially quad throttles) to a 1983 design analogue EFI system with one throttle and a plenum.

I can also tell you which has the most power everywhere else too...

[oldcorollas]

unless of course one unit can mix the air/fuel mixture better to create a better burn
carby people claim theyre emulsification method does this more effectively and thus, more power.

but i agree that the difference is likely very small, and efi is better/cheaper all round

"better" is a point of contention... carby ppl may say that it atomisies the fuel better, but...

what makes for a better burn? the more fuel you evaporate into gas, the less air can get in there, and the faster it will burn, and more likely to be uncontrolled speed burn.

small uniform droplets will burn slower and evenly and be "best"

large droplets, burn slower, maybe taking too long.

non-uniform size??

arguably, EFI will create more consistent droplet size across the rev and throttle range, whereas carby is much more inconsistent with the size of fuel droplets and amount of fuel vapourisation.....

some more to think about

[river]

Hi,

And whilst im at it - here's some REAL WORLD comparison that's appropriate to most people here..... my previous 18R-G.
Dyno w/stock Solex carbies: 68rwkW
Dyno w/stock EFI system: 73rwkW
..... that is the EXACT same engine, remove carbies and put on EFI. That's a change from two 40mm Mikuni Solex carbs (essentially quad throttles) to a 1983 design analogue EFI system with one throttle and a plenum.

I can also tell you which has the most power everywhere else too...

Unless the carbs were fully reconditioned and tuned by a pro (like Frank Kleinig) your results are flawed. Carbies require tuning and maintenance, ripping off a set of old untuned carbs and putting on EFI is hardly a fair comparison. When (or if) you get your carbs set-up and tuned properly, then re-do your test - until then it only shows what I have always said - carbs need to be tuned periodically to maintain their optimum performance.

The design of older performance carburettor engines (pre EFI days) were matched so the engine and carbs worked together to provide power through the entire rev range. It wasn't a slapped together system where the engine mostly performed well and then choked or died in parts of its rev range due to the limits of the carburettor.

You're incorrect in your assumption regarding anyone who'd prefer carbs on their personal car over EFI. I do. And while ever I own an 210-head 18RG I will continue to use carbs. Other than maybe providing a small amount of fuel efficiency, the EFI will not increase the power of the engine.

seeyuzz
river

PS: Yes, the carb vs EFI is an old and stupid argument, but I've seen far more pointless and absurd arguments within these forums.

[Draven]

stu: doesn't the fact that we're arguing for peak power at wot & specific RPM make that a moot point?

[oldcorollas]

are we? i thought the original thread question would have related to providing mixture at a significantly wider range of pressure than in an NA setup.. for a carb to match EFI in forced induction takes a lot more fiddling than most people would want to pay for. in terms of dyno time, number of jets tried, or even gaskets to seal the carb for each time you pull it apart...

[Draven]

right, I just read the first bit I came in mid-thread for the argument and missed the first few posts

[JustCallMeOrlando]

the EFI will not increase the power of the engine.

As much as I love to agree with you old timer, while you are correct that changing to EFI will not increase peak power, it WILL have more power everywhere else. You can argue till you're blue in the face about getting them tuned by a "pro" but in the end, you're trying to ask a whole lot of different things, from a simple mechanical device that's only capable of a few.

[oldcorollas]

CV carbs FTW

[YLD-16L]

I have never heard a sound so sweet as an 18RG with twin 45s at 8500rpm. It sounded like a car with balls.

I am not going to weigh into this debate though

[Norbie]

An EFI 18R-G with 4x45mm throttles will sound just as sweet, believe me.

[river]

Hi,

As much as I love to agree with you old timer, while you are correct that changing to EFI will not increase peak power, it WILL have more power everywhere else. You can argue till you're blue in the face about getting them tuned by a "pro" but in the end, you're trying to ask a whole lot of different things, from a simple mechanical device that's only capable of a few.

Perhaps. However, until I see a dyno graph of an engine with a perfectly tuned carby set-up versus an EFI on the same engine, I'm reserving my judgement.

I need to see such a graph so I can look at the difference. Don't get me wrong, I'm not saying EFI is no good - actually far, far from it. I think they're a magnificent fuel delivery system, but I doubt the differences between the two are large - certainly for normal driving. It's that difference I want to quantify between the two systems.

seeyuzz
river

[YLD-16L]

An EFI 18R-G with 4x45mm throttles will sound just as sweet, believe me.

Oh I believe you , but when you're a poor uni student a set of webbers was more "achievable"

EFI FTW ICNBA!!!!!!

[JustCallMeOrlando]

Simple, lets convert your car to EFI and we'll find out

[The Witzl]

easier still - just take mine for a quick drive. You will know straight away.