TBI spacers, are they really worth the money?

[slowburb]

You could remote mount coils on the firewall with longer plug wires, and there is no need for a plastic engine cover.

To each their own... I know someone who ripped a perfectly good electronic ignition set up and dual plug heads off a hog they were working on for a customer.

The second plug hole was welded shut, and points installed.

There is no denying the advantages of the LS though, the cylinder heads and general engine architecture is light years ahead of an old small block.

Now if GM would have only used nice high nickel blocks like Chrysler.....

The general architecture is an adaptation through reverse engineering everything done by ford and mopar.

 

[sethel]

I did all these upgrades on my 350 TBI at once about a month ago: The TBI Spacer, Fuel injector spacer, Adjustable FPR w/gauge, open air filter from the stock set-up, along with the "free" upgrade of grinding down the tabs on my throttle body as shown in the picture below (that picture wasn't a finished product but you can see the tabs are gone).

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I definitely went from 17 hwy mpg to near 14 mpg straight hwy. Nothing else had changed on my rig, didn't anticipate that. I definitely feel more throttle response and I'm still narrowing in on what psi to run my fuel pressure especially since I just changed my fuel filter (currently at about 13 psi). I am not happy about the drastic decrease in MPG's and not sure what potentially went wrong. My TBI spacer was a smooth bore, and to answer your question the "swirl" bore's are suppose to increase velocity in my understanding of them, but a buddy of mine who is a mechanic specializing in vehicle upgrades advised me that he believes they add more turbulence than anything. I also ground down the middle of my TBI spacer which was intended to equalize pressure between the two injector pods which you can see below.

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Here are the before and after shots of my engine bay you can see the fuel pressure gauge in the after shot where I cut my fuel lines and made up my height distance difference from the spacer with rubber fuel hoses.

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I was under the impression that my MPG's would not be affected and if they were these upgrades I would see slight gains. ANyone know why I lost significant MPG's? perhaps I F'd up somewhere, but I can't imagine how.

 

[Moparmat2000]

I bet the open element air cleaner hurt it a bit. Its now sucking in hot and less dense engine compartment air. Put the old air cleaner and breather tube back on, with a drop in K&N filter.

 

[someotherguy]

IMO, a case of "if it ain't broke..."

Richard

 

[sethel]

It's my understanding that the stock air cleaner is very restrictive and that removing this restriction outweighs the damage of an unrestricted air filter pulling in warmer air. I'll try that out however if that is the case I can't imagine warmer air would see a decrease of 3mpg. There's gotta be something else going on

 

[90halfton]

I did all these upgrades on my 350 TBI at once about a month ago: The TBI Spacer, Fuel injector spacer, Adjustable FPR w/gauge, open air filter from the stock set-up, along with the "free" upgrade of grinding down the tabs on my throttle body as shown in the picture below (that picture wasn't a finished product but you can see the tabs are gone).

You must be registered for see images attach

You must be registered for see images attach

I definitely went from 17 hwy mpg to near 14 mpg straight hwy. Nothing else had changed on my rig, didn't anticipate that. I definitely feel more throttle response and I'm still narrowing in on what psi to run my fuel pressure especially since I just changed my fuel filter (currently at about 13 psi). I am not happy about the drastic decrease in MPG's and not sure what potentially went wrong. My TBI spacer was a smooth bore, and to answer your question the "swirl" bore's are suppose to increase velocity in my understanding of them, but a buddy of mine who is a mechanic specializing in vehicle upgrades advised me that he believes they add more turbulence than anything. I also ground down the middle of my TBI spacer which was intended to equalize pressure between the two injector pods which you can see below.

You must be registered for see images attach

Here are the before and after shots of my engine bay you can see the fuel pressure gauge in the after shot where I cut my fuel lines and made up my height distance difference from the spacer with rubber fuel hoses.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

I was under the impression that my MPG's would not be affected and if they were these upgrades I would see slight gains. ANyone know why I lost significant MPG's? perhaps I F'd up somewhere, but I can't imagine how.

Performance enhancements hurting mileage? Lol

 

[someotherguy]

It's my understanding that the stock air cleaner is very restrictive and that removing this restriction outweighs the damage of an unrestricted air filter pulling in warmer air.

You've been misled X2

Richard

 

[Moparmat2000]

Salad bowl mod to stock air cleaner base, and dump the stock plastic TB to air cleaner spacer.

Jegs pn 555-50080 $44.99, or tape measure everything, and head to housewares section of walmart LOL.

This is the first mod to the stock air cleaner i plan on besides the K&N drop in i am using.

Pic isnt my truck, its from a different website.

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[Moparmat2000]

Performance enhancements hurting mileage? Lol

Upping airflow effiency like the TBI mods should not hurt mileage. At least i wouldent think so. This being said, i am not sure but maybe the combination of raising the injector pod, and removing the ridge on top of the TB throat is whats causing this problem.

The small lip on the TB throat around both venturis may be there to shroud the injectors slightly to help them direct their spray more efficiently. I am no TB expert by any means, so maybe someone can chime in here.

I think i am going to try raising my injector pod the 1/4" since its cheap and easily reversable, do the salad bowl mod and leave the ridges in place. But may concider tapering them outward for airflow.

 

[sethel]

Performance enhancements hurting mileage? Lol

You've been misled X2

Richard

TBI spacers and an open element shouldn't be as significant as a 3 MPG drop. I think something else went awry. I've seen many writeups similar that there were very little losses to MPG with the upgrades to performance that these provide.

Salad bowl mod to stock air cleaner base, and dump the stock plastic TB to air cleaner spacer.

Jegs pn 555-50080 $44.99, or tape measure everything, and head to housewares section of walmart LOL.

This is the first mod to the stock air cleaner i plan on besides the K&N drop in i am using.

Pic isnt my truck, its from a different website.

You must be registered for see images attach

Here is one such example where he practically got the same MPG and he used your salad bowl example...

http://www.gmc4x4.com/topic/1035-1991-57l-bored-tbi-upgrade-write-up-warning-lots-of-pics/