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TBI Porting

BadDog said:
Are you in a position to test this back to back with no other changes, not even fuel pressure? I would be interested to know if it makes a difference. Especially if you have access to a dyno (I wish I did) so that we can get real numbers. It's so very easy to "feel" a difference when there is none, I think it's wired into our brains to justify work and/or money invested. :D

From my reading and modest understanding of physics, I'm betting it makes little or no difference to low rpm and tip-in performance. It might even hurt due to air column dynamics. I have to believe they put that there for a reason, and my best guess is that is improves low rpm drivability at the expense of high rpm (which is typical of many of the related systems) and why the 3rd gen guys do it to help their quarter mile times. I’m only mentioning this again since that is counter productive to what most of us want in a 4x4, while being bang on for the “hot rod” types, so their reports of improvement should be taken with a grain of salt…

Oh well, I've got nothing to offer but opinions, in many cases based on reading opinions of others, so I'll move along now... :D Good luck and I hope it works well for you, but as I mentioned earlier, I'm getting ever closer to making the call to reinstall my stock TB. Hmm, one good thing about that, I'll at least have the chance to test it back to back while changing only one (well, roughly one) variable...
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No, I don't have dyno access or even a flow bench. Wish like heck I did. I have to base my assumptions on numerous other published articles and threads. I think you summed it up nicely though. The only doubt I really have is the radius people are adding. From all I've read the high performance cars using varying forms of TBI are relying on a fluted shape of induction even when the injector is way down inside the assembly. 3rdgen guys are the exception and follow the school of thought that promotes a radius. Of course they all have the GM throttle body and high rpm improvement may be inherent in that particular design.

These are only my opinions, if you have a chance to make a comparison make sure to post your results. I'd be very interested to hear about it.
 
Okay Russ.

Found an aftermarket part that may interest you. Since your current throttle body is radiused this part will put the all important flute shape back into your airflow signature and force the air back over the top of your injectors. It costs 40.00 at Advance Auto parts. It should restore the tip-in if our theory is correct by creating that air entry break & placing the mixing zone back in the funnel neck down.

http://www.hypertech-inc.com/powercharger.html

Here is a test on that product among others from CarCraft. They claim 8lbs torque and 8hp improvement.

http://carcraft.com/techarticles/116_0407_jake/index3.html

Not bad for a one piece installation if it's true. I would guess that the design would really improve with a 360 degree open filament like a K&N. You may get the best of both worlds with radius and flute.
 
Hmmm, I've got a soup bowl about that size... Wonder if I plasma the bottom out... :crazy: :wink1:

The apparent/intuitive function would seem to be pretty much ideal with the deshrouded (radiused) TB. You can just see how it would flow down around the injectors and in. But I'm prone to be skeptical about stuff like that if I can't see the results on a dyno. Particularly when the article and stated application are based on the stock shrouded TB. Air flow dynamics are so complicated that I find my intuitive judgement is often wrong when measured objectively.

Also, I wonder how that works with the breather. Seems it would require a special breather base.
 
BadDog said:
Hmmm, I've got a soup bowl about that size... Wonder if I plasma the bottom out... :crazy: :wink1:

The apparent/intuitive function would seem to be pretty much ideal with the deshrouded (radiused) TB. You can just see how it would flow down around the injectors and in. But I'm prone to be skeptical about stuff like that if I can't see the results on a dyno. Particularly when the article and stated application are based on the stock shrouded TB. Air flow dynamics are so complicated that I find my intuitive judgement is often wrong when measured objectively.

Also, I wonder how that works with the breather. Seems it would require a special breather base.
Click to expand...

The way I understood it that part becomes the breather base, fits under the air cleaner. ADDY: Worst case I will port match my K&N base to the Power Charger opening.) I'll let you know in 7 to 14 days - I ordered mine today. I would think you'll see the benefits even with the radius because the important area is where the air breaks over the lip of the flute and changes sign. So essentially you've restored the factory flute in a better design and retained the increased flow of the radius.

Here are some flow ratings I dug up for the TBI units.

http://dtcc.cz28.com/flow/
 
I have the powercharger and blueprinted TB. It works good, helps low end too. It is basicly a velocity stack. Helps speed up the air at low rpm. Cleans up turbulence on top end. I highly recomend Getting a powercharger. They also work good on stock TBs. Cheap mod you can acually feel. Works all thru the RPM band. The stock TBI aircleaner spacer is very restrictive. Opening it up with the power charger really helps.
Powercharger, injector spacer, and a 1/2 inch open plentium (NOT the 2 hole kind) throttle body spacer will give a very respecitable power increase for a small $100 investment.
Also once you start increasing air flow you really need an adjustable fuel pressure regulator.
 
I would say that anytime you do anything you need an adjustable. Friend of mine finally got that through my head and he's dead right IMO. My truck was running just under 13 stock, and picking up to 15-16 made such HUGE difference across the board that it blew my mind. After quite a few more mods I'm running around 22-24 psi right now and it works very well, but you can't run that pressure without some significant work...

But if you do NOTHING at all other than bump up to 15-16 psi, you'll notice a huge improvement on every TBI out there. Word of warning though, the recent cheap off-the shelf (and even AC Delco) pumps can't hold the pressure above 14-15 in some cases. You may need to get a good quality Walbro or similar. I'm running a 30+ psi pump from a 93 454 TBI (mostly found in MD vans) that is an almost drop in replacement, though it did requires some very minor tweaking.
 
i have milled and polished the bores on my tbi ,also installed the hypercharger power charger under the stock air cleaner, done the vrafpr set to 18 psi wot and it idles at around 8 psi, i put in a walbro 190 fuel pump. and i currently run a prom chip from hypertech that i will be changing sometime soon when i find a better one. with all the mods it runs great and I'm in the process of making the stock air cleaner a dual snorkel setup by fabing on a second snorkel tub will look just like stock one but on driver side. do this for more air.


Dudley
 
yes it will look like that. only difference is I'm going to be using part from a second tbi suburban air cleaner and I'm working a deal with another member on here for the tube and box that bolts to the core support. butt all in all it is the same thing. oh and i run a k&n air filter in it also.



Dudley
 
Look at the photos in my link and you'll notice that the drivers side is pretty close to the brake master cylinder. You may need to modify the air tube from a Sub to get it to clear. The one from the S-10 is already shaped to clear. :cool1:
 
I was able to modify the factory FPR and make it adjustable. The base of the regulator housing had a torx bit with a block-out pin tacked in the center. I was able to carefully drill out the pin to access to torx screw but the torx housing wanted to spin. Tacked the housing with a mig and wallah - adjustable.

Now to see if my crappy welds hold. :crazy:
 
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jiminycricket said:
I was able to modify the factory FPR and make it adjustable. The base of the regulator housing had a torx bit with a block-out pin tacked in the center. I was able to carefully drill out the pin to access to torx screw but the torx housing wanted to spin. Tacked the housing with a mig and wallah - adjustable.

Now to see if my crappy welds hold. :crazy:
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i also modified the factory one at first but then i went and spent the money for the vacuum reference adjustable one i got it in kit for from top-down solution's it came with everything and it works great. :D

Dudley
 
HarryH3 said:
Look at the photos in my link and you'll notice that the drivers side is pretty close to the brake master cylinder. You may need to modify the air tube from a Sub to get it to clear. The one from the S-10 is already shaped to clear. :cool1:
Click to expand...

are all the ones from s-10s the same? i might go looking for one like you got so i can make sure i clear the master cylinder.

Dudley
 
crash81 said:
i also modified the factory one at first but then i went and spent the money for the vacuum reference adjustable one i got it in kit for from top-down solution's it came with everything and it works great. :D

Dudley
Click to expand...
I'd like to hear a little more about that kit. Is all adjustment based on manifold vacuum? How much improvement did you see and in what areas?
 
crash81 said:
are all the ones from s-10s the same? i might go looking for one like you got so i can make sure i clear the master cylinder.

Dudley
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Mine came from a '91 or so TBI 4.3 liter S-10. Starting in '93 or so they went to the CPI setup and the entire top end is different.
 
jiminycricket said:
I'd like to hear a little more about that kit. Is all adjustment based on manifold vacuum? How much improvement did you see and in what areas?
Click to expand...


here is a link to the place i got the kit http://www.top-downsolutions.com/product_info.php?products_id=99&osCsid=eaa179244f2762df0bdc3dbad4a8c377


now to try and answer your questions. no you make your adjustment for the fuel pressure you want without the vacuum hooked up. that will give you the wot fuel pressure you want. but as so many people have problems with the motor running rich at idle with other adjustable regulators. this is where the vacuum comes in once you get the wot psi set lets say at 15psi. once you hook the vacuum back up when you are at idle it will pull the fuel psi back down to around 8 to 10 psi. that way it idles fine but as some as you stabe the throttle it goes back to the wot setting of 15psi. its kinda the best of both worlds i guess you call it. and if you search the site in this post you can just buy the regulator if you like but i opted for the kit cause of the extra springs to further adjust the psi. and the valve for the vacuum line that delays the vacuum change to make it work smoother. hope this helps answer you questions.i really like it because when i used the modded factory one i first tried it was great at wot but it loaded bad at idle. now it runs great wot and idles fine also.:D


Dudley
 
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