When does a stock TB/intake stop flowing enough?

[chevymec]

I was just wondering when you guys/gals have found that the stock TB/intake is exhausted and a 52mm/porting is needed? I dont plan on getting wild with this motor but I do have an LT4 hot cam kit for down the road. I know it old and may not be the best thing out but I dont want to take a lot of the DD out of the car as far as gas mileage and drivebality. Just a little sound and increase in power.

[duh]

the stock intake and T/B will flow more than enough for a hot cam.......

[96lt1m6]

around 450hp
but its still good to have a larger TB;)

[duh]

around 450hp
but its still good to have a larger TB;)

Just don't go too big......I've seen dyno results showing that swapping a stock (48mm) to a 58mm can actually hurt performance........

just an fyi

[chevymec]

If I did anything it would just be a 52mm.

[YZF]

Look at it this way, the RamJet 502 uses the same silly throttle body as an LT1 car...

http://www.fbparts.com/12499121.jpg

[96lt1m6]

48mm-52mm is plenty for a long time,unless you have alot of work or a full bolt on 6spd. i do not suggest any other than stock 48mm
Rick Abare runs 9.90s@138 w/58mm ASM
Ed Wright runs 9.90s@136 w/58mm BBK

[Jazz]

I went with a 52mm TB because I really wasn’t sure what my combination was going to flow and didn’t want to have to upgrade or get a new tune for a larger throttle body if the 48mm wasn’t flowing enough. I definitely agree that bigger is NOT better and most street cars are fine with a 52mm or even the stock 48mm. Unless a car has heads and cam I doubt the 48mm will be a restriction with bolt ons. The money could be spent better elsewhere. I’d also say if you’re running the stock injector you’re safe with the 48mm. If you’re not maxing out the injectors yet you probably haven’t maxed out airflow of the 48mm TB. I can understand how you wouldn’t want to limit horsepower because of a single component like a TB however, but the bottleneck is probably the heads/cam/exhaust and not the throttle body.

[ksmyss]

Look at it this way, the RamJet 502 uses the same silly throttle body as an LT1 car...

http://www.fbparts.com/12499121.jpgthat whole ram jet is a big pita. has anyone ever messed with one? the pcms are under the intake and gm even says its not the best design. they are made fro boats and i guess thats the only place it wouldn't get wet. we went through hell and back trying to get one just to idle and pull itself onto a trailer in a street rod. ended up having to have a whole new cpu setup made. the marine place that did it says they do alot of them. not a very good example to use LOL

as far as going to big, we did back to back dyno pulls with a stocker and a 58mm. the intake was already opened up so it was a 5 minute swap. 2 runs before and 2 runs after, the 58mm picked up around 7hp and 8 trq across the board. it's not like a carb were it also meters fuel. the motor will only take in as much air as it can use.

[duh]

as far as going to big, we did back to back dyno pulls with a stocker and a 58mm. the intake was already opened up so it was a 5 minute swap. 2 runs before and 2 runs after, the 58mm picked up around 7hp and 8 trq across the board. it's not like a carb were it also meters fuel. the motor will only take in as much air as it can use.

That's funny since the results we did showed 10hp loss across the board.....then again that was on a stock car no tune.....

[bym]

as said before, stock 48mm I think its good inough for 750cfm, wich actually the hotcam kit will no make more than that, stick with the stock tb, you wont see any impresive gains in the 52mm one for the price, stroker engines do like bigger tb, but stock cubes, mild cam, stock one is good enough :) be happy youl be saving up 200 bucks atleast for a while,

[bym]

reading again, I agree it might hurt, bigger does not mean better, same as with a cam, same as in the ports, same asi in a big tunnel ram manifold in old carb setups,
what your looking for is velocity not mass, stick with stock one!

[Z28pr0jekt]

It hurts to put a 58mm or monoblade on a non ported intake because there will be interference with the airflow but as long as the intake is ported for it, it will be fine

[ksmyss]

That's funny since the results we did showed 10hp loss across the board.....then again that was on a stock car no tune.....
ours was a full bolt on car. was your intake opened up for the 58mm?

[ksmyss]

i do agree that it should be towards the end of your mod list. unless you can get the gasses out fast trying to get them in faster won't do you any good.

[duh]

ours was a full bolt on car. was your intake opened up for the 58mm?

yes, infact I don't know of anyone that slapped a 58 directly onto a tpi/lt1 manifold because of the 48mm holes.......

[ksmyss]

yes, infact I don't know of anyone that slapped a 58 directly onto a tpi/lt1 manifold because of the 48mm holes.......
it will work, just not very well.

[96lt1m6]

Now the TPI 5.7 was very different the 52mm and the 58mm showed improvements only because the intake design SUCKED for what we were doing with the car....We did open the plenum to accept the 58mm and also grinded out the restrictions in the plenum.