How much can car performance be increased by performance shops and how do they do it?

Factual Questions
41

Half the kids at my high school got 700hp+ by adding a wing to the back of their Honda and using synthetic blend oil. They could also take a notoriously dangerous local Cloverleaf interchange at 90mph.

Every time we went to the track a missed shift or weak fuel pump or something would prevent them from running anything under 18 seconds, and if I was riding in the car they’d take the Cloverleaf at 30-40mph like everyone else because they were on street tires or they heard a cop was shooting radar from some nonexistent vantage point.

42

Shagnasty, Just replying to the part that I bolded.
If you check the results of Hot Rod Magazine’s 2013 Drag Week, the winning “1969 Camaro” of Tom Bailey did about 1000 road miles in five days, raced at a different 1/4 mile strip each day, and turned in a below 7 second slip at each track. Yes it is an absurd, over the top car that has few, if any, production parts: even the body is a composite replica. But it is legally licensed in the state it is registered.
The rest of your post I agree with.
Peace - DESK

43

I call B.S. on that 700 hp thing. Now if they added performance parts decals, hood pins, and a tachometer…maybe. :wink:

44

Point taken. I made a mistake in my first post. I should have said production, street-legal car because I think that is what the OP is interested in. To my way of thinking, it is fine to tune and enhance such cars to get better performance even by adding aftermarket parts or replacing the engine but it no longer counts if your ultra-high performance dragster mainly only uses the shell of the original model. That is a completely different category.

45

Roots-type superchargers provide less and less gain when operated at higher speeds, due to the heating of the air as it passes through the charger. Intercooling can help, but has its limits. There’s a reason people refer to the Eaton M62 as the “Heaton”.

46

This thread has veered off away from what the OP was asking and I’m late to the party, so I will get back to the basic question.

**How much can car performance be increased by performance shops and how do they do it? **

The first stage of improving performance is usually to increase the air flow through the engine. I see that turbo and super chargers have been mentioned so I will keep my comments to normally aspirated engines.

The first step to improving air flow through the engine is to add a Cold Air Intake or induction, (CAI). This delivers colder, denser, air into the combustion chamber. Cold, dense air contains more oxygen and thus more power. It helps to imagine that the car engine is just an air pump powered by fuel. Many new cars incorporate CAI as stock features of their performance engines now. The basic idea is to gather air from an input area that is not warmed by the heat of the engine.

The second step to increasing air flow is to reduce the exhaust restrictions. In some parts of the US this can be problematic due to DEQ testing requirements and various local laws. I live in a state that does not require DEQ testing outside of the urban areas.

To increase exhaust air flow you can install header pipes, individual tubes that come from each cylinder, and eliminate the CATS ( or catalytic converters). There are also high flow CATS that can be installed if you require them. Then install a free flowing exhaust system.

The oxygen sensors or O2 are usually eliminated unless the are required to pass DEQ. You can also install O2 simulators that will tell the computer that everything is fine with the exhaust gasses, even if it isn’t.

Once your intake air has been improved, and your exhaust restrictions have been reduced, your PCM or computer will throw a few error codes and light up your Check Engine light, or whatever it is called in your car. These error codes must then be tuned out by the shop, HP Tuners and various mail order tunes can do this, very poorly.

To maximize your newly freed up power you should take the vehicle to be Dyno tuned. Put on a dynamometer and have what is similar to a stress test a human may take to test their heart. A good shop will retune your PCM to optimize your power and take advantage of your new modifications. This can make a huge difference in the performance of the car.

State and local restrictions may apply. But air in air out is still the starting point, and best bang-for-the-buck for your performance dollar.

Also, stickers, each brand label or sticker ands at least 10 hp. :wink:

47

You can dyno tune with HP Tuners.

Mail order tunes aren’t as exact as a dyno tune, but they’re probably adequate for most people with simple bolt-ons. They’re a little on the conservative side, but most people with simple bolt-ons aren’t trying to risk blowing up a car just to gain a couple tenths.

48

I want to thank you all for an extremely informative and interesting thread. I never dreamed that cars had changed so much from the muscle cars of the 70s to modern cars.

You all have given me some incredible thing to think about and if and when I decide to proceed with some enhancements to my car, those enhancements will be targeted according to the info you have provided.

I can’t wait! Vroom! Vroom!

49

The same can be said of turbochargers but that’s what intercoolers are for. I had a factory turbo that put out 15 PSI and I bumped it up to 18 PSI which was pushing it. Also added a ram air system which helped with the spool time. above 45 mph you need only touch the gas pedal and it went to full boost immediately.