The posts in this thread have been edited and a link as been added to the ultimate TBI section of the "new to TBI thread" at the top of this forum. Thanks NEEDforSPEED!
Last edited by ShiftyCapone : 06-10-2004 at 01:04 PM.
i think im going to try to port this as far as i can, its off the car and i keep thinking i can take more off of it... hmmm im going to do the shafts next.... maybe today....
Originally posted by NEEDforSPEED i think im going to try to port this as far as i can, its off the car and i keep thinking i can take more off of it... hmmm im going to do the shafts next.... maybe today....
Don't knick the sides of the wall. I do not even bother with the throttle shafts because of that risk. You are not going to pick up any significant cfm from that as you do the casting wall.
Originally posted by NEEDforSPEED now that i think of it will that even help porting it more, or well the incomeing air be hotter becuz the unit wont be abile to disapat heat as well?
Hotter because you removed that little bit of material? Actually the fuel cools our TBI units and they are almost always cool to the touch when running. The next time you fire up your car feel the TBI unit after a few minutes.
This guy knows his stuff... and his parts work. Just read the article on his main page.
Unless you live in California.
Sheesh... I was considering a power plate after reading the information on that site but it might be just like the spacer I have. THAT mod can't possibly effect my emissions that much, can it?
yea id like to buy one thats already ported and stuff and install it... and give mine as a core.... (*** i wish i could do that)... i want to do that fuel pressure regulator mod but i have no idea WTF im doing... if i had some pics and some one to help me id feel better with porting and playing with TBI's
my baro at key on/engine off is 101-102, at 6200RPM with my motor combo, the MAP readings are still 101-102Kpa . . . with my stock TB, And I feel pretty safe is saying that I have probably have a significantly larger Air demand from my engine, than most poeple with 305 TBI's do.
I would be really interested to see someone who actualy has results showing any real power gain from all this grinding on the throttle body.
dewey u just confused me.. lol... more details? slower and smaller words... lol... im jp... but i really have no idea what that ment...
"my baro at key on/engine off is 101-102, at 6200RPM with my motor combo, the MAP readings are still 101-102Kpa . . . with my stock TB, And I feel pretty safe is saying that I have probably have a significantly larger Air demand from my engine, than most poeple with 305 TBI's do. "
Is my engine (305 with Ultradyne racing cam 206/216) needs to be shifted over 6k to take advantage of the powerband, the longer duration, and high RPMs mean my motor needs more air, than say a stock LO3.
When I data log, my map readings are the same as if my car is sitting is still, which means the sensors are not measuring any lack of air. So I see no reason why a motor that needs less air, would need a bigger TB than I have, when my car is getting all the air in needs (according to the sensors.)
Well, if i thought to myself, the map sensor is giving me the same readings when the car < edit > is running < /edit > as it is standing still, I'd think my sensor was setup wrong or i can't data log at all.
The map sensor should be measuring manifold air pressure which should definietly be below atmospheric (the engine is a air pump and air pumps dont work well with no vacuum on the intake) so your data logger is logging the barometric sensor as shown by it's reading of sea level air pressure at standard temp (or a bad map sensor). The baro sensor is what the map uses (i believe) and carbed motors use to measure the atmospheric pressure. The atmospheric pressure would definitely not change if you started your car up, but manifold pressure most certainly would. So your data does not reflect the map sensor readings at all. The only time they approach 1 atmosphere is when you are at WOT and you have a very free flowing intake setup, which is not what you'd have at < 1k rpms.
So, either your data logger is logging a barometric sensor, or you dont have the map sensor hooked into the manifold, or you dont have a working map sensor, or you have a really bad vacuum leak. Pick one, but in any case, your data is misleading you.
Porting the TB will definitely make a difference as the engine's air requirements can certainly be hindered by less than ideal air flow. Not necessarily the volumetric requirements of air, but the speed at which it comes. Of course, on bad heads, porting the TB wont help, because it's much less of a bottle neck, same goes for the way the TB gets it's air. You're only going to get the performance of your least performing link.
You just totally missed what Dewey was saying. Trust me when I say Dewey knows what he's doing. Yes his map sensor shows all kinds of different readings at part throttle. At full throttle he is saying that he has no restriction between the heads and the TB. The reason why he knows this is his MAP sensor does not see any vacume at WOT. The rule of thumb on a carb is anything more than 1.5" of vacume is a restriction. I converted that and it equals out to betwean 4 and 5 KPA which a metric measurement for vacume. So Dewey has no restrictions whith his TB. In order to prove that this mod does make more power you need to take a motor that can move enough air to pull vacume at WOT then swap to a ported TB and see if it decreases the vacume.
I'm running a luke warm 350 with a 454 TB and I get about 1-2 kpa drop at upper rpms. So I would say my motor would be a good canidate for this test. Unfortunately I don't have enough time to get a stock TB or test this theory. If any one wants to send me a stocker to test, I'd be more than willing.
No one is bashing this mod. It's a great mod because it's free, and it gives you an excuse to rebuild your TB. I just wouldn't go spending alot of money on it since there are so many other places to get more bang for your buck.
__________________ It's just a two barrel truck motor.......sorta
Originally posted by Dewey316 ...I would be really interested to see someone who actualy has results showing any real power gain from all this grinding on the throttle body.
I'd love to see it too. I think you'd find that he may have an suspension problem. You've essentially killed the direct port entry and any possible venturi effect that may help the fuel mixture at the injector.
The engine is pulling vacuum, just not any longer at the throttle body, due to it no longer being the restriction (throttle plates open). Indeed, the pressure at WOT would be near barometric pressure. I misread your statement about actually reving the car to WOT, after testing it off.
You're right though, the TB doesn't need to flow any more air but you'd also have to. But lots of people stand by injector spacers helping mix fuel in TBI's, and so porting the TB would have the same purpose. Not much gain for all the work, but you can't argue with your numbers. Without forced induction or a new engine you wouldn't require more air than the stock TB provides.
