Can you over throttle body a motor?
03-29-2005, 10:00 AM
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Can you over throttle body a motor? Guys, can you over throttle body a motor. I understand that you can over carb a motor which is generally resulting from too much fuel flow but can you have too much air in an injected 4 barrel fuel injection setup. My guess would be no but it is only a guess.
03-29-2005, 10:04 AM
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I dont beleive so there is no vacuum signal, no veturis (sp) used or nothing dependant on air velocity for fueling like a carb.
Edit
But then again how would a large TB affect the MAF since this is a heated wire element and air speed across the element is needed to heat up and cool down the wires. SD wouldnt care
Edit
But then again how would a large TB affect the MAF since this is a heated wire element and air speed across the element is needed to heat up and cool down the wires. SD wouldnt care
03-29-2005, 10:13 AM
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Originally Posted by HumpinSS
I dont beleive so there is no vacuum signal, no veturis (sp) used or nothing dependant on air velocity for fueling like a carb.
Edit
But then again how would a large TB affect the MAF since this is a heated wire element and air speed across the element is needed to heat up and cool down the wires. SD wouldnt care
Edit
But then again how would a large TB affect the MAF since this is a heated wire element and air speed across the element is needed to heat up and cool down the wires. SD wouldnt care
03-29-2005, 10:19 AM
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Originally Posted by DAPSUPRSLO
Guys, can you over throttle body a motor. I understand that you can over carb a motor which is generally resulting from too much fuel flow but can you have too much air in an injected 4 barrel fuel injection setup. My guess would be no but it is only a guess.
"While it is possible to use too large a TB, it's not like it would be if you used too large a carb, for the following reason. With a carburetor, the air going past the venturis "pulls" the gasoline into the air stream. This requires a certain velocity of the air to avoid poor throttle response and/or loss of low end power. Using a carb that is too large, slows down the airflow and causes this problem. With a TB, the gasoline is injected directly into the cylinder head (at the intake manifold) and is controlled by the computer, so a lower air velocity is not that big an issue. It's one of those "too big a TB won't help you, but it probably won't hurt you either" kind of thing."
03-29-2005, 10:41 AM
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Over 1000 cfm with an 8000rpm limit and 110%ve (the ve is not realistic though). Remember that most tbs are rated at a high vacuum then is actually seen when sitting on a manifold. Therefore it is wise to choose a higher cfm rating.
Humpin, how did you go about SD tuning. I was thinking of doing a closed loop SD tune and just using the ltfts to adjust my ve table. What do you think? I will be using ls1 edit and EFILive. I have a wideband for wide open throttle tuning as well as referencing my ltfts to make sure they are correcting for a 14.7 to 1 at cruz.
Humpin, how did you go about SD tuning. I was thinking of doing a closed loop SD tune and just using the ltfts to adjust my ve table. What do you think? I will be using ls1 edit and EFILive. I have a wideband for wide open throttle tuning as well as referencing my ltfts to make sure they are correcting for a 14.7 to 1 at cruz.
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03-29-2005, 11:42 AM
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There is a definite downside to having a huge TB. Your engine will reach atmospheric pressure in the manifold (assuming N/A) at a very low throttle setting which means flooring it further has no effect. You pedal feel will be very touchy since a small movement is nearly full output. Your tip-in control assumes the throttle must move "x" degrees and adds fuel accordingly. This can all be tuned for but the pedal modulation will be very sensitive. This assumes you really go overboard.
03-29-2005, 12:58 PM
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Thanks BJM, I will be going overboard intially as this will be going on a stock short block 346 with a big nasty cam and big ported heads. This motor won't come close to the tb I will be using. It will work for right now though.
Dirk, I don't have AIM. Plus I'm at work right now. Shoot me a pm here or EFA and I'll talk to you via that way.
Dirk, I don't have AIM. Plus I'm at work right now. Shoot me a pm here or EFA and I'll talk to you via that way.
03-29-2005, 02:35 PM
#10
the only effect of going too huge is what BJM said... the throttle becomes more touchy because a LITTLE bit more on the gas pedal is alot more air.... meaning you bearly push down the gas, and it goes alot more then it did with the stock pedal.
you go waay overboard and its impossible to drive slow, smoothly...
if you look in a OEM large throttlebody (regardless of make), you'll find these little "ribs" infront of the blade.
they make a restriction air has to go over atat small throttle openings... they're a kind of fix to keep too much air from coming in easily at part throttle.... at WOT, they dont hurt anything...
you go waay overboard and its impossible to drive slow, smoothly...
if you look in a OEM large throttlebody (regardless of make), you'll find these little "ribs" infront of the blade.
they make a restriction air has to go over atat small throttle openings... they're a kind of fix to keep too much air from coming in easily at part throttle.... at WOT, they dont hurt anything...
