technical questions about mod's
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technical questions about mod's
I'm just curious about a few things - first, does changing boost pressure, turbo size, fuel maps, etc. change the engine compression ratio? If so, at what point does that become unsafe for the engine? Second, does changing tire/wheel size affect the accuracy of the speedometer/odometer?
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if the diameter of the whole wheel changes than yes your speedo is off..
you'll need to recalibrate it....but most people when they get bigger rims they get skinnier tires to compensate so the diameter stays the same....
as far as the engine i'm no tech person so i don't know but there is always some risk when modding your car....the manufactuer designs your car for the best performance with reliability....
as far as the engine i'm no tech person so i don't know but there is always some risk when modding your car....the manufactuer designs your car for the best performance with reliability....
AudiWorld Super User
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Diff pistons will change comp ratio.
(i.e.) bolting a blower onto an M. You make more power with a charger (more then what most motors are designed for) so you need to 'slow down' the motor. The compression has to be dropped so your motor doesn't rupture.
Our VW/audi (1.8 motors particluarly or na 2.0's are safe untill 300hp. You have to open **** up inside if you want more boost.
Our VW/audi (1.8 motors particluarly or na 2.0's are safe untill 300hp. You have to open **** up inside if you want more boost.
Elder Member
Joined: Mar 2000
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not really
Funny given your email address, but that isn't how turbos work really at all.
First, you actually reduce the compression ratio when using turbos to reduce the liklihood of knocking.
Second, turbos don't increase compression ratio. If they did, they would increase your gas mileage (volumetric efficiency goes up). Instead, they decrease it.
Turbos do pack more charge (and gas) into your cylinder. But by doing so before the cycle starts, they beat some preignition problems.
Effectively, a turbo expands the volume of your cylinder (displacement) when in operation. Thus, you get more power when the turbos spool up, but also you get worse gas mileage when they spool up.
First, you actually reduce the compression ratio when using turbos to reduce the liklihood of knocking.
Second, turbos don't increase compression ratio. If they did, they would increase your gas mileage (volumetric efficiency goes up). Instead, they decrease it.
Turbos do pack more charge (and gas) into your cylinder. But by doing so before the cycle starts, they beat some preignition problems.
Effectively, a turbo expands the volume of your cylinder (displacement) when in operation. Thus, you get more power when the turbos spool up, but also you get worse gas mileage when they spool up.
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