For the price of ITB's I could get a blower

 

There are actually several ITB intakes around now a days. Tex Race Cars (part of Textralia) has one avaliable. I believe they are pretty reasonable.

Here is a picture of one of that one





This one is from another operation in Australia (Morrison Motorsports). These guys have ITB's for everything. GENI SBC, SB2.2, Ford, etc..


Same one used by Nathan Higgin on his C5R headed motor. Notice the unique injector placement (similar to the way you see a lot of high end race motors done).

 

Ok cant find links to any of them

 

^ I couldn't either. I was trying to find the tex racing website.

 

we've seen those before (other site) supposedly morrison has some real close workings with holden?

 

Looks like there is some connection to the Textralia pictures that J-Rod posted. This is the exact base set-up that I have. I got the parts from Hocking Racing in Australia, who claimed to have designed/built them. Didn't have the speediest transaction though...took 8 months to get the parts from start to finish. Approach with caution if you are in a hurry.

Seems to be of decent workmanship. No dyno numbers yet, but sometime soon. I'll post result once we are tuned.

T

 

Bump.

Killer info in this thread. Any more word on the problems people were having, or any other advances or info on the subject in general?

 

I have a question... It was brought to me by someone so I'll ask it. Arent those tb's a lot smaller than the 90mm? So the question is will it outflow say a Beck sheetmetal intake with a 105mm Tb on it. Keep in mind that all the cylinders do not draw air at the same time. How does a 50mm tb opening outdraw a 105 opening?

Just some food for thought, hoping to spark some more technical info.

 

8-50mm diameter tb's= 15705 sq. mm. surface area of throttle body.

1-105mm tb = 8654 sq.mm. surface area.

So the ITBs have a little less than twice the throttle blade surface area. Maybe that's why ITBs outflow a beck intake and tb.

In a ITB setup, each cylinder gets its own air supply. This means that each cylinder creates its own vacuum, and 1 cylinder doesn't suck on the supply of another cylinder. Maybe this raises the deltaP, because the air on the outside of the valve(in the intake runner) isn't being sucked(causing a low pressure) by another cylinder. This keeps the deltaP higher than it would be with a traditional single tb setup, and we all know a higher deltaP moves more air into the cylinder.

This make any sense to anyone?

 

I don't understand all of what you're trying to get at, but some things to keep in mind:

- An individual runner will be flowing air only during the intake cycle of it's associated cylinder, beginning with the exhaust scavenging pulse during overlap and ending near intake valve close. So that runner will be flowing no more than 35-40% of the time, meaning that an ITB intake requires much more TB area to maintain equivalent flow to a single TB intake.

- An ITB intake generally has straighter runners (because the runners don't need to connect to a common plenum). This can result in moderately lower flow restriction. However, that is not the primary benefit of an ITB intake. The primary benefits are 1). Easier optimization of runner length and taper, and therefore intake resonance tuning, to match the rest of the engine configuration, and 2.) the absence of cylinder-to-cylinder interactions from reversion, allowing for much more camshaft overlap while maintaining drivability.

 

This is closer to the discussion I was having with someone. Not all cylinders are drawing air at the same time so how can a smaller TB opening produce more power was the way it was put. You dont get the combined surface area of 8 50mm's.

 

Well by that token, the head port is MUCH smaller than the TB of an LS6 intake, yet that still restricts flow and power, despite being over twice as large as a single head port. And you could probably fit multiples of the valve area into the TB as well. So I don't think it's as simple as saying that "only 1 cylinder is drawing at any given time so a single TB is good enough".

 

Well, that's not what I was saying, in fact the opposite. On a V8, there are two cylinders in theory, and usually 4 cylinders in practice, drawing air from the plenum simultaneously, and airflow through the single TB into the plenum is effectively constant. On an ITB, air flows through each TB intermittently. The average airflow is the same, but because the airflow is intermittent, the peak air flow volume will be much greater than 1/8 of the constant flow volume through a single TB. Hence, comparing TB area between the two types of intakes is an apples/oranges comparison.

 

What about pressures and pressure waves ? Aren't they helpful, how are they effected with IT'bs?

 

All intakes exhibit resonant pressure or "wave-dynamic" effects, which can be quite significant in aiding volumetric efficiency in the tuned RPM range. The unusual characteristic "hump" in the torque curves of LSx motors in the 4000-5000 RPM range is primarily an effect of the candy-cane intake.

The tuning of wave-dynamic effects depends primarily on intake runner length, cross section, and taper. The ITB is therefore no different than other intake designs, except that the physical design makes it much easier to change runner length and taper by bolting on different "velocity stacks", and therefore easier to optimize for particular camshaft designs and desired RPM ranges.

 

That actually makes a lot of sense, if I think in reverse of what you wrote. In a straightline ITB manifold, Anything over the size of the head port "might" be big enough for the TB.

 

I plan on starting on making my own setup really soon. I already bought two sets of 2007 GSXR 750 throttle bodies. I forgot to measure the first set of shafts, but each runner tapers down to the back throttle bodies which are 42mm. They also have two sets of injectors in them. I'd like to leave the back set and use it with a stand alone fuel cell to control a dry direct port. Here's some pictures:

This is with the front set of throttle valves closed. I plan on removing these.

The throttle shaft also looks like it would be a really nice place to put a dry nitrous spray bar through.

Front throttle shaft open:


This picture didn't turn out too well, but it's of the hole in each runner.

I plan on getting rid of the IAC motor. Each cylinder has a little screw that lets you set the idle.

Back picture:


Back picture 2 with the all the throttle shafts open:


The odd fuel injector setup and the TPS sensor:


I've done a little mock up on a set of heads I have. I'm going to have to split them in half. They have a bolt at the top and bottom that hold them together. Once removed you end up with two sets of two throttle bodies. I removed the intake manifold and associated parts on my formula recently. I need to move it and wash it before any real work starts. I was going to start today, but it is absolutely pouring outside. Tomorrow should be a go though. I'll take pictures.

Does anyone know of a place where I can get LS1 intake manifold flanges?

I'm still thinking of a few ways to mount them. If anyone has any ideas let me know.

 

Beck Mechanical sells just the flanges if you need, last time I checked they were $175+ shipping, assuming who I was talking to knew what I was talking about.

I hate to say this but I believe those GSXR throttles are about 10mm on the small side for an LS1. IIRC its 115 cfm per square inch of cross sectional area, you'll probably want something around 2.6-2.75 sq in to be at a low pressure drop across the throttle body with heads that flow near 300 cfm at your cam lift.

 

maybe find a broke/scrapped single plane intake and cut it up for mock-up or template purposes...?

 

just a FYI guys my cam is a 247 252 @108lsa in a 383 lingenfelter CNC heads 11.2:1 SCR and it has the harrop 52mm intake. the cars idles fine at 900rpm and only bucks from 1k rpm to 1.5krpm in first gear. ******* car is almost like stock but pulls like a raped ape.