Here’s the Scoop

Chargespeed carbon hood duct for the GC chassis Impreza as shown on a customer car. A great, stylish option for guys running a front mount (or non turbo guys just looking to change up the look)

It’s Alive!

Guess which one belongs with toilet paper? OEM gasket was my savior last weekend. The Hondata one turned out to be poo

After sitting dormant since December 2008, I finally was able to use the Z again last weekend! After abandoning the ITB project earlier this summer, it really got to me that I hadn’t used the car in so long, so we set to task on getting it all back up and running. The plan was to wrap up the install of the new Cosworth intake manifold/throttle body, etc and then tune her last weekend. In the military they have some saying about planning to fail and failing to plan….we fought with the car all last Saturday but it finally turned out ok.

The plan was to have my buddy Mike from Innovative Tuning come down, tune the car on the road for a bit, and then we would put it on the dyno and see how things turned out. From fighting the alternator, the crappy Hondata intake manifold gasket, to several less than happy coilpacks, the car never made it on the dyno. But, we did get some street tuning in and I even got to drive it around during the week. The weather is supposed to be awesome here for the long weekend, and I’m really looking forward to some seat time.

Dyno will have to wait a few weeks till I can find a good weekend to trek up to Buffalo to Mike’s place. The car feels healthy, revs nicely, and has good pickup despite running stupidly rich (I have to recalibrate the wideband).

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320whp of NA VQ35 Goodness

Figured some of you might want to see a quick video of my car in action.  This was taken last November, I think on Thanksgiving day, before headed to the parents for the festive meal (the run would have been significantly slower post-turkey!).  Since the weather here has been so crappy, and I’m dying to drive the car, I figured I’d post a quick video to remind myself what it feels like!

And here’s a picture of it before we dropped it into the car (spring 2007)

It’s not done yet – got a few more things to go !  Hopefully it all works out

Exige Me?

Yesterday Shaun and I were bs’ing online, as we usually do on Saturday afternoons, and the talk turns to Lotus.  Admittedly, I don’t know much about them, except that they have always captured my imagination by being a performance oriented car, that is both attainable, and rare – two things I can always appreciate in a performance platform.  One car in particular caught my eye on ebay – the color scheme just spoke to me!

 

So, I had the Exige bug going, and last night before eating some mediocre sushi with Jonathan, he built an badass version on Forza – down to the stripes.  I’m not a huge video game person, but this thing was a blast….570 hp, around 2000 lbs.  I might be east coast, but I know how to say yee-haw! 

After watching Vettel win at Monza today (amazing BTW!) I started googling all things Exige, and found some cool stuff I figured I’d share.

Lotus has done a ton of development work on the car since it’s introduction.  One neat version was the 270E  was shown at Geneva this year and runs on your choice of three fuels – gasoline, alcohol, or methanol! (white car with green stripes in the gallery below)

And of course the grand daddy of ’em all – the car every Exige wants to grow up to be: Lotus’s own Sport Exige 05.  This was developed in conjunction with RTN (of Bentley LeMans winning fame), and is a V6 NA monster – 400 hp + 1974 lbs = hold the hell on.  

NA is Dead? Pt. II

In the last segment we looked at the very basics of an Individual Throttle Body setup, and the very basics by which it works.  This time around I wanted to go a bit more in depth and explore the different types of setups out there.  I’m also going to attempt to give some insight into various technical features of each type as well.

Trumpet type – this is the image that most people have in their head when they thing of an Individual Throttle Body.  Each airhorn, or trumpet is responsible for feeding an individual cylinder.   However simple it may seem, the design of the trumpet itself has a tremendous amount to do with the performance that can be extracted from it.  First, there is the length of the trumpet.   Just like in a sealed intake manifold, the shorter the runner, the more top end power the engine will have, and the longer the runner, the more low and midrange power it will have.  Altering the design of the bell also has alot to do with the overall powerband as well.  These are the most simple type out there, as they use a simple butterfly valve to ingest air to the combustion chamber.  There are several key elements in the design one chooses for their trumpet style.  These will vary from engine to engine based on many factors, such as combustion chamber design, valve placement and diameter, cam lobe profile, etc.  The proper taper of the trumpet will give you the best of all worlds – sufficient low speed volume so the car doesn’t become peaky, but providing significant velocity when the valve is fully opened, to mid and top end power.   The trumpet design as mentioned, is highly interdependant on many other aspects of the engine.  If anyone is interested in some helpful math formulas, let me know and I’d be happy to post them. 

The above pictures shows a typical trumpet style ITB setup on a modern V6 engine.  Note the taper of the trumpet that continues to the intake runner itself, providing a balance of low, mid and top end performance.

Slider ITB – Slider style throttle bodies were born out of logical belief that with the traditional butterfly valve style, you are giving up prescious air volume and velocity by having a shaft in the center of the bore.  In a slider ITB, there is no throttle shaft.  Instead, there is a door that slides open and closed to ingest air.  As you can imagine, the packaging requirements tend to make these more space hungry and more expensive to produce.  These are also said to give non linear throttle response, making them difficult to drive at lower speeds, and difficult to maintain a steady state speed.

Typical Slider Type

Roller Style – the roller style throttle body is the third type of individual setup out there.  In this type, you have two barrels, one that rotates inside another.  These are essentially combining the linear throttle progression of a traditional butterfly setup, with the pure flow of the slider type.  As you can imagine, these are the post costly to produce, and leave the least margin for error, as you no longer have the ability to alter runner length, taper,  etc for a given application.  Each component has to be machined on it’s own, meaning it’s got to be perfect out of the gate.  The inner roller uses ball bearings for smooth and linear actuation. 

Get your math right, your patience high, and a bunch of buddies to chip in on a CNC machine, and the roller is clearly the way to go from a packaging and performance standpoint.  But there really is no margin for error.

Here is a very neat video showing a roller throttle body in action on an STi

So, now we’ve seen the different styles of ITB’s out there.  In the next segment, we’ll get a bit more into design considerations of the most popular version, the butterfly style.  This will include injector placement, trumpet location, and what all is needed to actually make one of these setups run a car.

Stay tuned!!!

NA is Dead?

All too often on the web, you see guys talking about making big hp on cars through forced induction. Whether it’s a supercharger, turbo, twin charged, etc., there is always someone pushing the envelope here.  But what about good old fashioned NA power?  No boost, no having to inject various concoctions of combustible chemicals to be able to crank the timing – just plain ordinary air? I think it often gets left by the wayside.

I wanted to start a multipiece series on NA tuning, with particular emphasis on what to many people is the pinnacle of an NA setup – the Individual Throttle Body, or in web language, ITB. Let’s just get a basic understanding of what an ITB is and how it works.

As the name implies an Indivdual Throttle Body (ITB) means each cylinder has it’s own dedicated path for the air to reach the combustion chamber.  The bodies are linked together so that they open and close together, thus allowing the engine to ingest the air required for the combustion process.  There are several benefits that an ITB setup can have over a single throttle body.  First and foremost is cylinder balance.  With a single throttle body, you have little to no control over how much air is ingested into the the combustion chamber for each cylinder.  As a result, you end up with air reaching the combustion chambers in varying amounts, at various speeds, which can leave you with cylinders producing different power levels.  The amount this differs of course varies by the application.  With ITB’s there is no sharing of air.  Each cylinder is afforded unlimited air, and through tuning, the user can ensure that each cylinder is ingesting the exact same volume per air, at the exact same velocity. The second benefit is throttle response. With each cylinder now able to ingest it’s own dedicated stream of air, the combustion process starts quicker, and the engine responds faster to throttle inputs.  Furthermore, because you now have individual paths of air vs a large single path, the volume of air and the velocity that can be ingested into the engine as the throttle plate opens is often more than a single throttle body setup allows.  We’ll go into more detail on this last point in a future installment, as well as determining the right manifold design for a particular application, all with real world testing, graphs, videos and dynos!

As best I can tell, the first production car to use both ITB’s and fuel injection was the very rare BMW M1. This car was manufactured from 1978 to 1981, and used a combination of ITB’s and a mechanical fuel injection system developed by Kugelfischer and Bosch.  BMW still uses ITB’s today on their M series engines.

In the next installment, we’ll look more in depth into various ITB setups as well as design differences, etc. In the meantime, take a look and listen at this clip from Option Video from Japan of a tuned Acura with ITB’s.  If this doesn’t make you fall in love with an automobile, it’s pretty safe to assume you have no soul!