MR. KIDD

Ok I'm running a 406 with ported AFR heads and a 58mm throttle body have any of you went from a 58mm to a 1300 and had any improvement.Also why do the LS1 use 75mm throttle bodys stock and even larger when modded and here I'm using a 58mm with a 406 I'm thinking it would perform better with the 1300,what you guys think?

sofakingdom

iTrader: (1)

IIRC a dual 58mm flows about 1100 CFM.

A 400 at 100% VE and 7000 RPM flows about 800CFM.

Instinct tells me, you'll get more bang for the buck and the trouble, someplace else.

All that increasing the TB size will do, is make the car harder to drive at low throttle openings; because just a small movement of the huge TB will result in such a gigantic increase in air flow.

Ricktpi

Depends alot on the rpm your engine is operating at. You can measure the vacuum in the plenum at max rpm & WOT & then compare to atmospherical pressure, if it's the same or close you don't need it. LS1's have a single 75mm TB, you have a dual 58mm. Area wise, you have slightly more than a single 75mm.

MR. KIDD

So why is the Ls1 not experencing a sensitive throttle with its 75mm

MR. KIDD

Would you mind explaining that because it seems like your saying that each blade is 58mm I have never measured one but I don't think they are. so what am I missing?

TTOP350

iTrader: (8)

They are 2 58mm blades...

I have been running a stock T-body since 91..

its a bit modified tho.. I took it apart bord it to 52mm then cut the center out an boom i made my own mono blade...
I have run it on several diff motors in my car from a 305 all the way to 454 small blocks and it worked just fine on all of them...

DID NOT hurt drivability at all

BTW it flows 1200 cfm by itself
if its on a 305 it will only flow enough for that motor no more no less
on a bigger motor it will flow more

no majic or vodo there

will you get big hp increase with a big t-body on a small motor prolly not
but if you go from a stock t-body to a big 1 on a big motor you will gain power....

five7kid

iTrader: (14)

502 Ram Jet crate engine:

"Description:
"The ... Ram Jet 502 crate engine from GM Performance Parts makes 510 horsepower at 5500 RPM and 550 ft-lbs of torque at 4500 RPM. GM engineers and Pro Mod racer Harold Martin combined together to design the unique large plenum Ram Jet intake that produces the broad torque curve using only a L98 throttle body assembly." (emphasis added)

Yep, need a lot of TB to make power. . .

Admittedly, slightly different system than your run-of-the-mill TPI, but hopefully the point made.

TTOP350

iTrader: (8)

yep....
I put a bigger t-body on one of those and picked up over 20rwhp and with a better cam picked up 80 more

GM leaves a ton of power on the table

moneyman380

On my stock 350 i noticed a inprovment in power by just changing from a stock TB to a 58mm BBK TB. Now i have a superram which is made to accept the 58mm TB. WOW

sofakingdom

iTrader: (1)

The LS1 TB is a single bore, 75m; the 58 dual is ..... surprise .... dual 58mm bores. Nearly 20% more bore area. 4418 sq mm vs 5284 sq mm.

You will only get more power from a flow type of mod like a TB, if the thing you're changing is the restriction in your system. If the restriction is elsewhere, it will accomplish nothing; because the system as a whole will still flow the same amount. Otherwise, all you'll accomplish by increasing the size of the TB, is to create the effect of the twitchy throttle I mentioned.

I still think the dual 58 is plenty for a 400, and that you won't make any significant improvement with changes right there. It already flows all that the motor can use.

anesthes

iTrader: (12)

Lots of interesting responses to this thread. heh

So whats your MAP readings at WOT throughout the RPM band?

I've experimented with a few different setups, various throttle bodies, etc.

-- Joe

Ricktpi

Since we know the area of a circle is: pi x radius squared
75mm (radius 37.5mm) 37.5 x 37.5 x 3.14 (pi) = 4415.625 sq. mm.
58 (radius 29mm) 29 x 29 x 3.14 (pi) = 2640.74 sq. mm.
4415.625 sq. mm < 2640.74 sq. mm x 2 (5281.48)

jwscab

yeah, to answer the question of why the LS motors are not as sensitive, the ones that are cable operated (and not drive by wire) use a progressive cable pull, looks like a snail shell, far from the center line of the throttle shaft closed, and near the center at WOT. It changes the percent opening at throttle to percent opening at your foot relationship, so it 'slows' the throttle opening to allow greater control. the later LT1 engines and later TBI engines have this as well.

I also concur on making sure you need the larger blades, making sure the other restrictions are improved before moving above 52mm.

MR. KIDD

Thank you and everybody that responsed.

MR. KIDD

Mine is a Maf car.

MR. KIDD

[QUOTE]Originally posted by Tony Walch
[B]

I have been running a stock T-body since 91..

its a bit modified tho.. I took it apart bord it to 52mm then cut the center out an boom i made my own mono blade...
I have run it on several diff motors in my car from a 305 all the way to 454 small blocks and it worked just fine on all of them...
BTW it flows 1200 cfm by itself
Do you have pictures of it and how did you flow test it?

anesthes

iTrader: (12)

Yeah I see that it's an 85, but I figured you might have a vac gauge, or have converted to speed density.

-- Joe

TTOP350

iTrader: (8)

[QUOTE]Originally posted by MR. KIDD
[B]
I dont have pics but I need to get some put up...
Tested on a flow bench @ a well known shop in the STLouis area
I also made a 4" maf but never finished tuning with it .. due to customer cars that needed work..
Here is a link to some of my cars pics

http://www.team3rdgen.com/modules.ph...view_album.php

sofakingdom

iTrader: (1)

What MAF is on your car? How much does it flow? More than 1100 CFM or whatever? If not, the MAF is your restriction, not the TB; you could put a 6" diameter TB on it, and not one more molecule of air will be able to get into the engine than with the one you've got.

That's whay I don't think changing the TB will give yo more power.

TTOP350

iTrader: (8)

I have a stock gutted MAF.. I know they dont flow as much as the big T-body by far..
It does show a big gain when I put the big T-Body on. Y? I dont know either, but it picks up a few tenths at the track and several hp on our rwhp dyno... and it doesnt lie.... tooo much LOL
my motor is far from stock 4++ cubes
on a stock 350 with LTRs it picked up around 3-4 hp not setting the world on fire but hey it was a improvement..

brutalform

Tony, I know this thread is a few months old, and I was searching on a monoblade TB, and this came up. Not to be off topic, but I looked at your pics, and it funny, that the one with the girl has the most views of any of them.