Just so we don't HI-JACK anymore threads...........putting larger wheels on vehicles does increase handling and performance. That's why ALL the automotive community i.e. GM, Ford, Dodge and the inports have increase all their wheel sizes..........

EDIT: In this thread you can talk about anything performance.

It increases Road grip and Look, but thats all very dependent on the supension setup and the brakes and the drive style. Large rims if used correctly with a wise tire choice is a good thing but is just rice or over kill bling on the wrong car ex: SUV's, H2, honda civic, various american cars, you get the picture. Also large rims are not always the best choice for a ride if that ride was not designed for large rims, you may think it makes you faster but it really does not. I think unless your racing your car alot and very hard your not going to need a rim any bigger then a 18 but most imports should go with a 16-17 because any bigger without upgrading the brakes and making room in the wells and tighting up the supension your just wasting your time and money.

Anyone know of inexpensive tap that you can add to cover a cold air intake to shield it from the heat of the rest of the engine? Or anything that can work like that?

I have 17 inch rims and low profile tires, best 900 dollars I ever spent.

PSI produced in a forced induction set up means zilch. The things that matter are static compression ratio, timing under boost, cam profile (read: the true dynamic compression ratio) to figure out BMEP and efficiency. The cylinder pressure is a sliding curve scale based upon the above mentioned factors. Also a more efficient engine (better exhaust and intake design/low restriction) but identicle internal specs and have lower PSI in the manifold while using the same "pump". It's performance will be at a higher scale than the other.

Static compression ratio is a valuable number but no indictation of knocking point in regards to octane requirements. Cylinder head and piston head designs, materials, cam profiles (again helping figure out the BMEP pressure) are the true deciding factors. Decreasing compression ratio via increasing piston distance from cylinder head via shimming with gaskets can often cause knocking, while reducing the compression ratio. This is caused by the fact many heads with a quench style head will work inefficiently and allow uncontrolled burn if the distance is increased. Timing requirements for quench style heads are different than most others because the flame happens faster, less advance it required. Timing to the "standard" 37 degrees in a modern engine often can result in melted pistons.

The best piston head designs are flat tops, sometimes stepped. Domed and dished pistons while valuable in finding the desired static compression ratio are often more prone to cause flame travel problems.

Current day high performance aluminum alloy pistons are nearly as good as forged. Forged pistons while stronger aren't always the best investment short of the highest of demanding engines. Forged pistons true advantage are for manufacturers that are only interested in a short run not the end consumer normally. Also alloy pistons are lighter which increases the life for your bearings.

Rod ratio is a very under appriciated number in the designing of a high performance engine. When building and engine use the longest possible rod. This will be as important to your maxinum RPM potential as the valvetrain. The longer the rod, the less stress on the bottom end - and when your rpms are climbing, the strain on your bottom end is very notable, hp/torque output aside due to speed and harmonics.

Cams are the cheapest horse power you can find. They're also the most dramatic and it's very easy to choose incorrectly. I will not get into cam to much here because it wouldn't do this choice justice. There are entire 500+ pages books on cams.

Cylinder head flow is a great thing, but large valves will make the engine feel lazy. Trading flow velocity for total flow is often a bad investment for a regulary driven vehicle. Also don't select heads based upon flow above .45 if you're engine will use hydraulic lift cam shaft - the time a .55 lift cam truly spends above .5 is so marginal to the total intake event that it isn't worth considering if another head has better characteristics below. Also there are two measuring systems commonly found on wet benchs. Make sure you're using apples to apples comparisons.

Eh.. I'll think of more later.

Quote: Originally Posted by Highperf15 Just so we don't HI-JACK anymore threads...........putting larger wheels on vehicles does increase handling and performance. That's why ALL the automotive community i.e. GM, Ford, Dodge and the inports have increase all their wheel sizes.......... EDIT: In this thread you can talk about anything performance.

Okay... Tire size as far as WIDTH may be a contributing factor, as you have more of a footprint on the road. 18" wheels usually will match up with factory spec (issue or two ago on Import Tuner said they encountered some wheel-rub on the 350Z w/ 18")

20" tires on a family sedan are NOT going to do that much for you...

You'll have wheel rub... lowering your ride at that point will probably just make it worse... Now then, you can jack it UP, but that kind of defeats the purpose of low-profile.

Without proper camber support, your wheels are going to angle out. Thus actually reducing the effectiviness of the tires in general...

Then the joys of the suspension... when stopping, your suspension and brakes are optomized to stop in a certain way to make sure that all four wheels are providing proper pressures to the weight distribution of the car. Without proper adjustments, this will make stopping uneven, and even dangerous.

Some aftermarket big-brake kits actually degrade performance... so unless you wanna shell out $2,500.00 for a Brembo kit...

Anyway... big wheels for a car designed for it are cool... otherwise, unless you wanna do a lot of work, I'd pass myself...

When assmbling your heads - put the valves into your drill press and use very fine sandpaper to polish them like a mirror. This allows you to make sure they're true and will increase their life/guide life.

Use studs over bolts when possible in assembling an engine. They cost more for the same PSI strength, but their value is in the distribution of force over the entire gasket area.

Plasma-moly pistons rings are a wonderful thing, and extend the life of your cylinder walls and less likely to butt ends under heavy load. Also don't forget to file your rings to the spec's of your engine's usage. RV/tow engines require more gap than a N/A street engine due to increase risk of butting. Same with forced induction, as piston rings expand more in these conditions. Fuel type are also important factors.

Crankshafts - some high performance shops offer many options for crankshafts from nitrate hardening to cross drilling the oil holes. In my opinion your best bet is to buy a forged crank (or maybe billet it you're going to get crazy out there). The cost of hardening on often times a 30+ year old cast crankshaft it's not worth it. If you're doing a mild build up, go ahead keep it, get it balanced. But otherwise just buy new if possible. More often than not additional holes for oiling in the crank is not needed and infact more prone to cause harm than help. Chamfering the oil holes is a good investment though.

High quality bearings aren't nice, they're required. Why spend 5k+ on an engine and try to save 30 dollars on parts that can make or break it? Clevit 77s tri-metal bearings are very safe bets for domestic engines. There are some better options at times, more often than not, worse. Best way to think of bearings isn't as a wearing surface really - they're biggest importance is the imbedding of particles into themselves to keep contaminates from eatting your parts alive.

Fuel injection vs. carbs. You can make the same horse power with a carb as you can a multiport fuel injection setup. But if you drive from high alt. to low alt locations regularly, EFI is a winner. Also will not have any risk of stumbling off the line because a float moves during heavy acceleration *coughdangholleyscough*. But hey, you just need a screw driver and some jets to fix any carb problem.

Biggest part of performance - knowing what you want, why you want it, being honest with yourself, and how when adding prices together for a project to hit the multiply key then 3 then enter.

Ohh - yes larger wheels assuming you can keep simular weight (tire + wheel combo vs combo), larger is better on the track and smooth roads. Lightweight large wheels are spendy and easy to bend. Rarely do you see them, but they do exist. Where you're getting your concerns Dark I'm not sure but they're wrong. Suspension isn't even in Highperf's statement. Even assuming large wheel + 2" drop even that in no way means there will be rubbing if stock total diameter, width, and proper off-set is used. Yes a person can make a first class jackass out of himself with just buying a random Dub that "fits", this is rice. Buying lightweight 20s even if only 17" are needed to clear the brake calipers doesn't in itself condemn anyone. Low profiles aren't my thing, but it makes the vehicle feel like it's on rails. There is no denying that. Riding on rails is the perfect description too because you feel every bumb easily though. But there is a handling benefit there.

Now I'm not saying put 22"-24" wheels (like you showed on that yellow Impala), I said 20" wheels and most of your new cars nowadays can and will accept 20" wheels with no problems. Take the new 2005 Mustang.......That will accept 20" wheels with no problem. I agree that it's not for all cars, but there are alot of them out there that can. One thing that I NEVER heard of was a brake upgrade that decreased the braking performance of a vehicle (I'm talkin about name brands here, Wilwood, Brembo etc.)

I personally prefer smaller lighter rims and tires on a car. It reduces the unsprung mass of your vehicle. The weight of the wheel is also located closer to the axle centerline. If you are going to spend all that money and bother with larger rims so you can pack in bigger brakes why not go one step further and fix the original problem, your car weighs to much. If you could drop 200-300 pounds or more of useless interior weight (back seat, booming stereo, silly upholestry ) besides it doesn't cost anything to remove stuff like that. Then you could get away with factory diameter brakes with just better rotors and pads and it will stop like all heck. The less weight you have in your wheels and tires makes your suspensions job of keeping them on the road easier. The closer that rolling mass is to the axle, the faster they will accelerate. I have seen some really nice rims in 16in. and most cars with them will spank an equal model with 20's

Ohhhh...........I'm not say that 18"-20" wheels are for everyone or every vehicle. I'm just saying that there are some benefits plus, depending on the style of the wheel to the application, the look of the vehicle can be improved on........Kinda like what Chip Foose does.