Throttle Body Size Question
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
Throttle Body Size Question
I know a 58MM throttle body can draw more air than I can utilize with my set-up and I'll see no performance gains with it. My question is, will it hurt my performance?
Safety Car
Joined: Jul 2001
Posts: 4,871
Likes: 15
From: Detroit's West Side MI
The short answer is "no". The engine will suck in as much air as it can use. It can't bring in too much.
Plus, if you have an LT1 car, the openings in your intake manifold are only 52 mm, so you'll basically be putting a 52 mm TB on your car.
Plus, if you have an LT1 car, the openings in your intake manifold are only 52 mm, so you'll basically be putting a 52 mm TB on your car.
Instructor
Joined: Mar 2007
Posts: 117
Likes: 0
From: San Luis Obispo California
I haven't run one, but I'm told it is difficult to run a 58mm with the stock cam. I think it might have something to do with the throttle position switch. I'm going to one with the stock cam and an intake that will utilize the extra flow, and I'll let everyone know how that works out.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
When the air coming out of the 58mm throttle body hits the sharp edges of the 52mm intake openings it will create turbulance which will screw up air flow....
IMHO this is the main reason the 58mm throttle body has gotten such a bad rap...
My 58mm throttle body stays on my intake manifold modded with 58mm openings!!!!!
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
I'll have to check if TPIS ported my plenum to 52mm or 58mm. I'll bet 52mm...
I can't imagine that with all the obstructions in the MAF and TB itself that at little restriction at the plenum could affect air flow enough to affect performance.
I can't imagine that with all the obstructions in the MAF and TB itself that at little restriction at the plenum could affect air flow enough to affect performance.
Last edited by geezel; Apr 11, 2007 at 09:30 PM.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Same day; 18 runs on stock TB , 12 runs on 58mm.
No changes except for resetting TPS.
Same ET / mph.Same 60 ft times which proves no loss of bottom end as frequently stated
Excellent off idle response ,SOTP felt better but not shown in time cards.
Only downside was harder to "tickle" the throttle off idle like when moving slowly forward in traffic but possibly due to very stiff spring on BBK TB.
By NO means a good " bang for buck" investment on a stock or mild engine; there are other mods that will give you more improvementfor your $$$, but your engine will not die
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Le Mans Master
Joined: Apr 2005
Posts: 8,077
Likes: 4
From: Scarborough ONTARIO
geezel: i just install ASM 58mm TB yesterday, logged only 15 miles or so, biggest problem is idle is not smooth, at the same time i install new TPS and IAC valve along with coolant TB bypass, i literally fight with adjusting IAC an TPS but still i could not smoothed out idle. Yeah i followed instructions how to set TPS and IAC.
Also i hooked up my laptop Winaldl, before and after, Blm's reading low (Rich) with 58mm TB and high (perfect 128 ) with a 52mm TB BBK. So i like BBK than ASM but iam biased, ASM looks nice and lot better than BBK though. BLM's with 58mm are 110-122 which is too rich with same Fuel pressure (52 and 58).
The only difference aSM comes with IAC custom housing, may IAC pintle not extending much dont know i will figure out in a day or 2.
But i saw mustangs 4.6L comes with 59mm or 61mm Twin TB stock, and they upgrade thiers to 65mm or 69mm TB.
If u still have Stock TPI plenum i recomend sending to TPIS to port for 58mm TB thats 100 bux worth it, they did mine 2 yrs ago it was worth.
OR u can do urself, http://www.geocities.com/jgkov/PRPort.html.
sami
Also i hooked up my laptop Winaldl, before and after, Blm's reading low (Rich) with 58mm TB and high (perfect 128 ) with a 52mm TB BBK. So i like BBK than ASM but iam biased, ASM looks nice and lot better than BBK though. BLM's with 58mm are 110-122 which is too rich with same Fuel pressure (52 and 58).
The only difference aSM comes with IAC custom housing, may IAC pintle not extending much dont know i will figure out in a day or 2.
But i saw mustangs 4.6L comes with 59mm or 61mm Twin TB stock, and they upgrade thiers to 65mm or 69mm TB.
If u still have Stock TPI plenum i recomend sending to TPIS to port for 58mm TB thats 100 bux worth it, they did mine 2 yrs ago it was worth.
OR u can do urself, http://www.geocities.com/jgkov/PRPort.html.
sami