Cerridius

Just a quick question for my application, Im wondering if its time to upgrade my throttle body from the stock 48mm to a 58mm.

I have Ported heads with bigger valves the CC503 camshaft, 1.6 roller rockers, K&N CAI, Pacesetter longtubes with ORYpipe/cutout through a borla PROxs

Yesterday at the track during the heat of Texas in july my can ran 8.1 at 85mph with a 1.80 60ft. I can't seem to get my 60ft down anymore, im not spinning with my radials. And after a dyno tune a few days ago my car put down 355rwhp and 412rwtq, tuner said my KPA was at 95 during WOT pulls, so im guessing i have some vacuum at WOT,

My goal is to break down in to the 7.xx 1/8 mile without nitrous and gears. Im sure I can get it during better weather.

only thing left that is stock is the throttle body? time to upgrade?

96lt1m6

iTrader: (31)

Doubt you will see much gain.... bigger cam and ported heads possibly.

Cerridius

I don't see why I wouldn't with my stock throttle being the only bottle neck left

za355tx

iTrader: (108)

A stock TB will support up to 400 HP and a 52mm TB will support up to 475. With your numbers a 58 mm will more more than you need...but if you plan on going bigger with your setup you might want to go ahead and get a 58 since the price will be pretty similar.

Just an example here...my dad sold a BBK 58mm to a guy who was running 11.30's with a stock TB. After switching to the 58mm he picked up a tenth...so not a ton of gain on an already stout car.

RamAir95TA

iTrader: (2)

Not worth it, unless you don't mind spending $400 for a HP or two.

Having said that I went with a 58mm because I had money to burn. Ed will also chime in about this I'm sure. It is hardly a bottleneck as you think.

Carguy8888

iTrader: (1)

Registered and learning.

Cerridius

So is 95kpa not that big of a deal?

I need more get off the line power or gears I guess... I'm not spinning my radials and I tried launching it different ways and the best I could get is 1.8

Ed Wright

iTrader: (1)

Did you pull your intake ducting and air filter off for this test? No more power than your making certainly does not require a larger TB, MAF, or anything else.
Some don't seem to grasp the brunoli effect. Look where the LT1 MAP is located. Then air moving past the nipple (love that word), same effect as a pain gun. Your not actually pulling that much vacuum. It's the MAP sensor location. It amazes me the supposedly "pro tuners" telling people what they need to change to cure this. Put a vacuum tap in the back of the manifold for the MAP, and see your "restriction" magically disappear. My 600 hp LT1 only pulls 2 KPA @ 8500 RPM, with a stock TB, and the MAP sensor tapped in out of the air flow path.

You ain't seeing what you think you are. Any "tuner" that tries to tell you that you are pulling that much vacuum with a 350 hp engine, well it just shows you how sharp they are.

This has been discussed here many times.

Cerridius

Tuner never told me to buy a new TB. All he said was the KPA was at 95 during WOT.

I'm the one that wants another mod to shave .2 off my 1/8 mile in this hot TX weather so I can get a 7.99 without gears or nitrous.
And I've read about all these throttle body arguments which is why I still have my stock TB with almost everything else done.

No I haven't ran the car yet without the intake ducting and filter.

Ed Wright

iTrader: (1)

If you had dynoed it that way you could have gotten an idea if there was a restriction there. At your power level I would guess not. If you know somebody that has one, maybe you could borrow it on a test n tune night at the track.

gjohnsonws6

iTrader: (12)

Unless you buy one used or a cheap one you could have more power for the same amount of money spent. You could swap out the cam if the heads are decent, or install a better y pipe if you are using the pacesetter which has a junk merge. One thing to do is check the throttle body shaft and see if it is tight, if it is loose then of course a little upgrade to a stock ported 52 wouldn't hurt.

lt1-xjs

From what I've seen the ls1 lid mod is the best, I'd go that route. Your peak power is @ 5600 and seems low. That cam and heads should pull to 6500 with ease. You may have a spring issue.

wrd1972

iTrader: (12)

Power drop off looks a little like valve float. Maybe weak valve springs.

Cerridius

I have the crane 10308-1 kit.

Maybe the cam is too small for the heads? Just the little 503 cam. Heads flowed a tad more than LE1 for comparison

Ed Wright

iTrader: (1)

I keep hearing from guys talking about "restrictions" and "bottle necks", if your engine does not pump more air that a given component can flow, it is not a restriction or bottle neck. The more power an engine makes, the more air it pumps, the more fuel it needs. It's a friggin air pump.

A low hp engine does not pump much air, thus does not need bigger, higher flowing TBs, MAFs, air boxes, etc. If your under 500 at the tires, why not spend your money on something that will actually make your car faster?

Guess if you just like to stick more aftermarket **** on there for no reason, I guess it's your money, your business.

Jason94z

iTrader: (3)

Agree do the chrs1313 intake and LS1 lid for the ram air. I wouldn't touch the TB at this point.

pillarpod

What do you mean by this and what does it do? Is this a mod that everybody should do or just higher HP people?

Cerridius

I think I've tried the LS1 lid but couldn't get it under my hood.

What about porting the intake to 58mm for the future but putting a 48mm back on. Will that hurt anything?

Ed Wright

iTrader: (1)

It means if you want to know if or how much vacuum it is pulling, get the vacuum gauge connected someplace out of the incoming air stream. High velocity past the end of the vacuum nipple cause a vacuum in the nipple, and gives a false reading. Pretty simple. Just think about it. You know how a paint gun works, right?

RamAir95TA

iTrader: (2)

No, but why?