Loss of torque with EFI?

[Roadknee]

In weather that was 100 F, 28.4", 100 % humidity, I have dropped six Holley jet sizes in a carb that was previously tuned at 55-60 deg. F, 30.2" baro, 40 % humidity.

This is the benefit of EFI in a street car

[jmarkaudio]

In weather that was 100 F, 28.4", 100 % humidity, I have dropped six Holley jet sizes in a carb that was previously tuned at 55-60 deg. F, 30.2" baro, 40 % humidity.

This is the benefit of EFI in a street car

For those that have tunable EFI do you really ever stop tuning?

[gmrocket]

In weather that was 100 F, 28.4", 100 % humidity, I have dropped six Holley jet sizes in a carb that was previously tuned at 55-60 deg. F, 30.2" baro, 40 % humidity.

This is the benefit of EFI in a street car

For those that have tunable EFI do you really ever stop tuning?

Believe it or not,, at the EMC I have watched a team sweat profusely over their laptop trying to correct an issue ...they were actually sweating,, wiping sweat off their faces without physically lifting a finger

Then see a non EFI team tear apart a carb, while everyone is watching, they have to move fast, not make any mistakes, seal it up, think and act quick at the same time....check for leaks,, get out quick and restart....

Cool as a cucumber,, no panic or breaking out in a sweat..like a well oiled machine

Makes you wonder which is actually easier and less stressful?

[hoffman900]

This is the benefit of EFI in a street car

For those that have tunable EFI do you really ever stop tuning?

Believe it or not,, at the EMC I have watched a team sweat profusely over their laptop trying to correct an issue ...they were actually sweating,, wiping sweat off their faces without physically lifting a finger

Then see a non EFI team tear apart a carb, while everyone is watching, they have to move fast, not make any mistakes, seal it up, think and act quick at the same time....check for leaks,, get out quick and restart....

Cool as a cucumber,, no panic or breaking out in a sweat..like a well oiled machine

Makes you wonder which is actually easier and less stressful?

Stress is very much on the person, not the fuel delivery type they’re using. LOL

[GARY C]

In weather that was 100 F, 28.4", 100 % humidity, I have dropped six Holley jet sizes in a carb that was previously tuned at 55-60 deg. F, 30.2" baro, 40 % humidity.

This is the benefit of EFI in a street car

For those that have tunable EFI do you really ever stop tuning?

Odly enough the big sales point for EFI is that its suppose to save you from the old days of having to tune your carb but as we all know, in some cases it won't even start the car let alone be any where near a tune.

[peejay]

I've always been a fan of retaining manifold heat for this reason, although not necessarily for "torque" but fuel economy. Even a "hot rod" is driven 99% of the time at idle and low load, why sacrifice that?

Some manufacturers used a heated electric grid under the throttle. I know Nissan did on the last of their TBI cars in 1990 (the trucks kept it a while longer), I'd like to say Ford did on some cars as well. Others just went with routing coolant to the area, which works fine once the engine is warmed up, but not as good in the critical warmup period.

I’ve been driving a 1995 TBI truck since 1999, puting 130k miles on it. The water heated plenum works better than you’d think during warmup. I
Think this is because GM’s fueling algorithms were better thought out than today’s aftermarket EFI. I can’t count the times I’ve started my truck in 0 degree weather, drop it in gear and go. It runs and idles flawlessly cold as it does hot.

Might be acceptable for a truck, but completely unacceptable for the tighter emissions standards in a car. That is why TBI died out in cars much earlier but kept going on in trucks for a few more years.

Warmup emissions is something like 90% of the emissions that need to be controlled and most of the rest of the 10% is evaporative.

This is a lot of why direct injection is so popular. There are NO enrichments needed. Once the O2 sensors are awake then they are in closed loop, and the catalysts light off very fast thanks to better understanding of exhaust geometry (and a little help from cam timing changes during warmup - you can hear when a modern car is in cat light-off mode on a cold start) The whole idea is to get into fuel control as soon as possible to minimize the amount of cold start pollution.

[peejay]

This is the benefit of EFI in a street car

For those that have tunable EFI do you really ever stop tuning?

Odly enough the big sales point for EFI is that its suppose to save you from the old days of having to tune your carb but as we all know, in some cases it won't even start the car let alone be any where near a tune.

I'd much rather tune EFI than a carb. It's a lot faster and cheaper, once you get into playing with emulsion tubes and various channel orifices and air bleeds that require a lot of patience and extra parts since they still haven't figured out how to make a drill that makes a hole smaller

Even if everything is adjustable, like the Dell'Orto setup on one of my cars, you can easily spend a few hundred dollars in jets and bleeds and the inevitable torn gaskets.

There are other things that are adjustable with EFI that you couldn't touch with a carb without an early 80s level of vacuum hose nesting. The last time I had my laptop plugged into my car, one of the things I was playing with was the air temperature correction curves, because I wanted to be able to make the engine run richer when fully heat-soaked as a means of thermal management.

And, once you have a tool, the tendency is to USE that tool. I admit that I would buy a modern car only if it was supported by HP Tuners so that I could go in and tweak things like throttle response. The only modern manual transmission cars I've driven that don't actively fight you throttle-wise have been Subarus, and Subaru seems to equate clutch stiffness with performance, which is a no-go for me.

[Dan Timberlake]

Don't the OE TBI systems have a water or exhaust heated heat exchanger between the TB and the manifold to heat/vaporize the fuel?

I recall a personal experience with a carb spacer on a '66 289 Ford where removal of the sharp edge that was upward-facing into the flow caused a huge loss of low end torque (added over a second to the 1/8th mi. time) and tanked the mileage from 25 to 15. No joke, no BS.

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The attached image is from one of my favorite SAE papers, 720214 - " Design refinement of Induction and exhaust systems using steady state flow bench techniques " by some folks at American Motors.

Aside from the orientation and location of the sharp edge. it would seem to me to offer a highly credible explanation for your 289 experience. Especially the mileage part.

"Where mixture preparation by the carburetor is deficient"

[Dan Timberlake]

If that were the case then Indy cars, Formula 1 cars, Nascar cup cars and almost all other venues of racing in the world use EFI. Why, I guess as many Carb nuts surmise they just haven't heard about how good carbs are yet ! HA

A simple answer here is that within those venues, ultimate horsepower is just not as important as other fuel control parameters like response, part throttle & wide open throttle fuel mileage and actually using almost no fuel on deceleration; giving up a few horsepower to gain in those areas is HUGE.

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And then there is trying to retain good, consistent throttle response in those pesky hi G corners on rough tarmac when the fuel level in the carb bowls is turning to froth and assuming crazy angles.

[gmrocket]

If that were the case then Indy cars, Formula 1 cars, Nascar cup cars and almost all other venues of racing in the world use EFI. Why, I guess as many Carb nuts surmise they just haven't heard about how good carbs are yet ! HA

A simple answer here is that within those venues, ultimate horsepower is just not as important as other fuel control parameters like response, part throttle & wide open throttle fuel mileage and actually using almost no fuel on deceleration; giving up a few horsepower to gain in those areas is HUGE.

==============.

And then there is trying to retain good, consistent throttle response in those pesky hi G corners on rough tarmac when the fuel level in the carb bowls is turning to froth and assuming crazy angles.

Nobody is arguing EFI isnt better in all those situations.

This whole post is about the difference at wot on a stationary dyno

[Brian P]

A stationary dyno is a contrived scenario. All the other stuff is what happens in the real world

[GARY C]

For those that have tunable EFI do you really ever stop tuning?

Odly enough the big sales point for EFI is that its suppose to save you from the old days of having to tune your carb but as we all know, in some cases it won't even start the car let alone be any where near a tune.

I'd much rather tune EFI than a carb. It's a lot faster and cheaper, once you get into playing with emulsion tubes and various channel orifices and air bleeds that require a lot of patience and extra parts since they still haven't figured out how to make a drill that makes a hole smaller

Even if everything is adjustable, like the Dell'Orto setup on one of my cars, you can easily spend a few hundred dollars in jets and bleeds and the inevitable torn gaskets.

There are other things that are adjustable with EFI that you couldn't touch with a carb without an early 80s level of vacuum hose nesting. The last time I had my laptop plugged into my car, one of the things I was playing with was the air temperature correction curves, because I wanted to be able to make the engine run richer when fully heat-soaked as a means of thermal management.

And, once you have a tool, the tendency is to USE that tool. I admit that I would buy a modern car only if it was supported by HP Tuners so that I could go in and tweak things like throttle response. The only modern manual transmission cars I've driven that don't actively fight you throttle-wise have been Subarus, and Subaru seems to equate clutch stiffness with performance, which is a no-go for me.

Probably ok if your doing enough to justify the initial cost but for the 2 things I would like to address on my 09 2500HD 6.0 it will cost me hundreds of dollars with little to no performance improvement but if it was a carb it might cost $10.00.

[In-Tech]

Gary, What are you wanting to change?

[GARY C]

Gary, What are you wanting to change?

Would kind of like to reduce the delay of the drive by wire and stop it from dropping so much timing when it shifts and possibly the shift time and firmness but the timing issue my help that as well.

[peejay]

Gary, What are you wanting to change?

Would kind of like to reduce the delay of the drive by wire and stop it from dropping so much timing when it shifts and possibly the shift time and firmness but the timing issue my help that as well.

I won't tell you what you should and should not want, but when the OEMs cut timing or throttle like that during a shift, it's so the trans can shift without being under load. Transmission life goes up dramatically when you do that. The trans guy I'd go to said that it is not uncommon to see transmissions with 200k miles on them and you can still see the printing on the frictions.

But yeah, I think for your vehicle, if you have the 6 speed, it gets expensive to go in there (at least with HPT) because the trans controller is separate from the engine controller, so it gets licensed separately.