Kredz28

mods in sig...im guessing the setup i am running now is good for about 400 rwhp..I am looking into getting the arizona speed marine 54mm throttle body. Is is worth it in a FI setup? How much rwhp would this be worth in my case.

detroit1994z28

I would defently upgrade the throttle body with forced induction. Because it will allow more air into the intake. I did come across a chevy magazine that actaully did a test with a supercharger and adding a 58mm and picked up an extra 20rwhp. I have a 58mm holley and I did notice better throttle response. I would defently go with a 58mm - But you will need to open out your intake

DavesLT1

if you're still running a stock 48 mm TB, then yeah you'll want to bump it up a little bit. 54 mm is the max you can go before you'll need to open the intake some. I've heard people say they've done it by stuffing some rags with oil on them into the intake and using a Dremel or other similar tool to port the openings.

Kredz28

Very interesting...i think i will be going with the 58mm...does anyone have pics of the port job on the intake?

detroit1994z28

http://www.bfranker.badz28.com/96ss/58porting.htm ---Thanks to Brent This site will give you step by step instructions. I followed this site and mine came out very good. I recommend a 58 holley throttle body. It will run around 150.00 more then a bbk but it's well worth the money. Anyways good luck with it - Mike

Kredz28

thanks a ton for that website...i will follow it word for word...i found a holley 58 on tbyrne for 289$ buying it tommorrow!

detroit1994z28

289.00?? Thats a deal. I paid exactly $450.00 for mine from that same exact place a year or so ago. - Good luck with the project - Mike

ramair96ws6

Ive made over 750 rwhp with the stock throttle body on an LS1 car
and over 650 with a stock throttle body on a LT1

markinkc69z

Consider that a supercharger is increasing the air density and overcoming slight restrictions without much loss. If your throttlebody is glossly undersized then an upgrade certainly won't hurt. The increase in throttle repsonse is likely due to the larger area presented at lower throttle openings. Velocity is still a consideration for cylinder fill and throttle response in a boosted application so don't get crazy on a stock upper end. You want good torque when not under boost.

While a bit off topic I recently spoke to a customer who made 1005 fwhp with a slightly modified 700 Holley. It underscored to me that it is not necessary to sacrifice driveability on a centrifugal blow through application.

engineermike

Velocity is NOT a concern through the throttle body. Port and runner, maybe, but not in the throttle body. You could put a mono-blade on it and it wouldn't lose any low end or torque.

markinkc69z

I'll disagree, but I am referring to part throttle operation. Here is an excerpt from a GMHigh article on a Z06 crate engine and TB velocity and why its helpful. (@ WFO) I'll offer more substantiation later.

GMHigh:
More Air
As of our last test the Z06 is sitting at 442 hp and 425 foot-pounds of torque. We were already ahead of our hoped for output here so the hurdle was moved to 430 foot-pounds and 450 hp. The question now was what simple bolt on we might do to achieve that goal. One of the moves that More Performance does on the LS6 engines going through their shop is to airflow the throttle body. Whereas this makes little difference to the lower powered engines in this range it does help to better satisfy the higher air demand of the more powerful LS6 variants. These mods involve cutting one side of the throttle shaft within the air stream away and thinning the remaining half. In addition to this the edges of the butterfly are formed to better split the air. Lastly the passages that connect the throttle body to the IAC valve and the valve cover vent are filled and two small holes that allow the function given by the large and now filled holes are drilled. All this adds up to a substantial 150 cfm plus in terms of extra airflow. Also, because the diameter of the throttle body has not changed the velocity of the air into the manifold plenum is increased. As this higher velocity enters the plenum it slows and some of the kinetic energy involved is translated into pressure. This helps boost the density of the charge entering the cylinders. At least that's the theory involved. On the dyno our Z06 with the More Performance throttle body produced the results shown in Fig. 4. In short our new target was met and surpassed. This Corvette crate motor was now producing 430 foot-pounds and 453 hp.

engineermike

First of all, I didn't say it wouldn't help full throttle hp and torque. Conversely, I said it wouldn't lose any low-end with a LARGER throttle body.

What a load of crap!!! This is a perfect example of a magazine editor writing about something he totally doesn't grasp. It is true that when a gas passes through an orifice at high speed, then slows down, the velocity-head is recovered and the static pressure increases. What he left out is that the static pressure increases to almost what it was upstream of the orifice. Here's how it works. . . air is at atmospheric pressure and no velocity. It passes through a throttle body at high speed. The static pressure of the air decreases as the speed increases (bernoulli's principle). When the speed decreases in the plenum, the pressure recovers back to atmospheric, but NOT ABOVE.

Also note that in their test, the hp increased much more than the torque.

97WS6Pilot

So how would an airfoil in the throttle body effect Low End Torque and High speed power in a boosted application?

engineermike

It will only add to both, more power than torque, though.

markinkc69z

The idea of velocity is to accellerate and store a higher pressure in the manifold than it would normally contain when not subject to boost. Nearly all engines experience a vacuum under WOT in the manifold with a stock throttle body. While you less than delicately suggest that pressure cannot be increased over the starting pressure you assume the inside of the manifold is at atmospheric when often it is not. The increased velocity can pack the air in and keep it there increasing the density (due to the kinetic energy of the air) over what it would be at low velocity. This is similar to a proper ram air setup where the inlet is smaller than the plenum or airbox. The air gets somewhat trapped inside.
I mean you have to wonder what the factory was thinking by creating a throttle body that creates velocity. Do you think they purposely leave them small so aftermarket companies have something to sell? Is there nothing to it?
Sorry if you feel its a load of crap, but if you have a boosted engine there are more rewarding places to spend that $300+.