Header Design Secrets: Interview with John Grudynski of Hytech Exhaust

This past week I interviewed John Grudynski, the owner, artist, and innovator behind Hytech Exhaust.

John has been designing and building race headers for many major racing series and organizations such as SCCA, USAC, Trans-Am, World SportsCars, Dirt Track and NHRA Drag racing for nearly 30 years. He is easily one of the foremost experts on the "black art" of Header design and has an incredible reputation in motorsport and in the aftermarket.

John has also developed some seriously impressive aftermarket headers for cars such as the Honda Integra Type-R (which gained almost 20hp over factory), the Eclipse V6, the RSX Type-S and many more.

John also earns the distinction of being recognized as one of the Tuner University Certified Experts and the first to receive the honor. This honor is one given only to companies and individuals who have earned their stripes and demonstrated unique abilities and innovations in motorsport, OEM, and aftermarket parts/services.

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Posted in Engine, TU Premium | 1 Comment

How to Compare Weight Savings to Horsepower Gains

Have you ever wondered what 10 or 20 extra horsepower might "feel" like in your car?

Maybe you've wondered how removing 100lbs will affect your car in terms of how much horsepower you'd have to gain to accomplish the same thing.

These questions are wise to ask because they can be used to make significantly better modification choices and frankly it can be fun to "simulate" different modification scenarios.

For example, if I could buy a carbon fiber hood that weighs 20lbs less than factory, it'd be nice to be able to view that weight loss in terms of horsepower. In other words, how many horsepower would I need to gain in order to accomplish the same thing as losing 20lbs? (Hint: it's pathetically little)

What if I wanted to determine if a dual exhaust system is worth while? How much more power would I have to make to offset the extra 20lbs? (in a 3500lb car with 215 hp, not even 1.25hp, so probably do-able)

Can someone on the forum claiming to feel a 1-2hp gain on their butt dyno really do so? Well, using this formula you'd see that they'd have to be able to feel the difference between having groceries in the car vs not having groceries in the car to "feel" that supposed gain.

What about if I wanted to see how much weight I'd have to lose to compete with the same car with 50 extra horsepower?

All of these kinds of questions can be answered with the simple math in today's article.

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Posted in Engine | 3 Comments

More Bad News for “Drop-In Air Filters”

In previous testing, which I don't believe I ever posted here, in my IS300 I found that there is actually MORE restriction created by the aFe filter for the IS300 (due probably to the construction of the filter - more on that in a later article if I can find the pictures).

The HKS air filter (foam) flowed -slightly- better, but by slightly better, I mean less than 0.1 inches of water better which is so little that it literally makes no difference at all. The K&N was a similar story to the aFe.

I don't care what your butt dyno says because frankly, it's the most deceptive thing on the planet and you can't feel a 1-2hp difference... no matter how good you are.

But there's worse news for the drop-in filter crowd. Unfortunately, as expected, they also filter a lot worse than the factory paper air filter. Over time, that means more wear on your engine. Enough to matter? Maybe not, though some foam filters are pretty awful and I can only imagine how bad those cheap eBay conic filters are.

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Posted in Engine | 2 Comments

Stiff Stuff: Strut Bars and Braces

No matter what car you drive, there are a number of suspension braces available to supposedly improve handling. People shell out hundreds, even thousands of dollars on strut bars, under body braces, suspension member braces, fender braces, and frankly braces that attach to just about anything that has a bolt in it.

But what do these bars really do, if anything? Are all braces the same or are there important differences between them?

In today's article, I hope to begin to decode a little bit about each of these extremely important questions. While everyone just assumes they wouldn't be so popular if they didn't "work", I am here to tell you that there are far more bad products on the market than good ones - especially when it comes to chassis braces.

I am going to limit my discussion here to strut braces as they are generally the most effective and common. However, aside from placement, all other braces you can fit to your car are going to have a similar function. Continue reading

Posted in Braking & Handling | 4 Comments

Clever Tricks for Improving the Location and Height of The Center of Gravity

Most enthusiasts are aware that lowering a car's center of gravity is good for handling and indeed, grip.

It's easy to see the real world implications as well when we think about how a tall SUV handles versus a very low Ferrari or Corvette.

Where the Center of Gravity Is

The car's center of gravity has both a horizontal (x, y) and vertical (z) location and actually refers to a single point where if suspended, the car would balance perfectly (at least in theory).

So vertically, we already know that the lower the center of gravity - the better. What about horizontally? Well, again, take a look at super cars - the closer weight is to the center of the vehicle the better. This is why super cars are typically mid-engine, so the heaviest part of the car (the engine/transmission) is closer to the middle of the vehicle.

The center of gravity in most cars is roughly at the top of the front bumper in terms of height (just a very rough estimate). The (x,y) coordinate of the center of gravity is much more variable, the Y being affected by the car's front and rear weight distribution. So in most cases, the CoG is at bumper height, somewhere in front of the midline of the car as you look at it from the side of the car. As you look from the front of the car, it is going to be either in the driver or the passenger's lap as most cars are slightly heavier on one side or the other.

Improving Center of Gravity - Vertically

Lowering a car is one way to improve the vertical center of gravity. This will offer increased stability, lessen the risk of roll over in extreme situations, and in most cases increase lateral grip (or the "g" handling figures on the skid pad). There are practical limits on how low you can go due to road imperfections and so on. There are also limits on how low you can go on a factory suspension without actually hurting handling. Usually around an inch of lowering is the farthest you can go without serious changes to your suspension geometry... but more on that in another article.

Vertical CoG can be improved by removing weight or choosing not to locate weight high in the vehicle. You can also get a CoG advantage from choosing a vehicle without a sunroof. Sunroofs in modern cars are around 25-30lbs, but in older vehicles they were sometimes 40-60lbs. In any case, take note that BMW thought it worth the exceptional expense to use a carbon fiber roof on many of their M vehicles. A few pounds on the roof of a vehicle can make a significant difference on the track, and 10-15 lbs can make a noticeable difference even on mountain roads.Having removed the sunroof on a car before, I can say that removal is not ideal (reasonably expensive) and you'll be better off to start with a car without a sunroof if possible.

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Posted in Braking & Handling | 2 Comments

How much Horsepower Can My Engine Make?

Without adding forced induction, many people want to know how much horsepower their car can make. Typically there's some pretty wild theories about how to get there and what that figure might be. However, there's a very straight forward way to figure out the theoretical maximum for your street car (as long as boost is not involved).

Volumetric efficiency is a term that (basically) refers to the ability of an engine to convert air and fuel into power. More accurately, it's the engine's ability to make use of the available air around it.

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Posted in Engine | 3 Comments

A Better Way to Compare & Anaylze Engine Efficiency

People often talk about horsepower per liter when they're comparing two engines. For example, you might say that the JDM B18C engine in the Integra Type-R produced 210hp from 1.8 or an impressive ~ 117 hp per liter. You may then be tempted to look at an engine like the 2JZ-GE found in project Lexus and scoff at it's 215hp from 3.0L, which is a mere ~ 72 hp per liter. Many IS300 owners are previous Honda guys, so, naturally, this is a very common 'scoff' :).

However, there is a better method to compare two engines (and also figure out how 'developed' an engine already is) which while also with its faults will give you a much better idea of what you're dealing with.

BMEP is one of many figures that you can use to compare engines. It stands for Brake Mean Effective Pressure and it refers to the amount of average pressure generated on the piston during combustion. BMEP gives us a much better idea of how 'developed' an engine is, how much stress/pressure is on the engine internals, and to some degree, how effective that engine is at converting gasoline to power. While this article mostly deals with Naturally Aspirated engines, it can also be used on forced induction engines - however, note that the BMEP values for these engines will be much much higher.

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Posted in Engine | 9 Comments

The 5 Best Bang for Your Buck Mods

If I could do only 5 performance modifications to a car, with cost being a consideration, and perhaps also wanting to strongly avoid "ruining" the car, what would I do?

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Posted in Braking & Handling, Engine | 4 Comments