Outer Limits 4x4 Board

Hi guys, have been kicking around with many ideas and have an ideal plan for my zook but it's money i'd also like to spend else where as im just a uni student etc etc.

nehow off that topics here's the question and all your help would be much appreactied.

if i was to ru 30x9.5x15 or 29" tyres with the extractors and engine back 2inch exhaust system i have on my 94sierra would i need to do ne other engine work????

cheers

I don't want to sound rude, so please don't take offence, but:

More power does not compensate for bigger tyres, only gearing can. There are two factors at work here - the increased diameter lowers the revs for any given road speed compared to a standard tyre. Extractors etc generally make very little difference to low rev torque, so there is no real gain here. the other factor is the increased weight, rolling resistance and wind resistance of the bigger/wider tyre. All of these things need torque to overcome.

Nearly any modification on the 1.3 (perhaps except supercharging, which is not really economically viable if done properly) will not usefully increase torque under the peak (below 3000rpm) so you end up having to thrash the car higher in the rev range in lower gears to get better perfomance than the stock tyre/stock engine setup. If you gear the car back to standard with the bigger tyre, then you st least get back to the engine working in its intended range and you can make the most of any (small) performance gains you are likely to get.

Extractors may or may not add any power to a suzuki. Power increases of over 10% are unlikely and under 10% cannot be detected by the "seat of the pants"

Mostly, the car will sound better and rev out cleaner.

A standard suzuki in decent tune shouldn't have any problems with either tyre unless you are doing lots of steep work.

A useful way of regearing the car cheaply to suit around a 30" tyre would be to fit a 1.0 litre transfer case. This would take your gearing pretty close to stock.

to give you an idea of shat gearing can achieve, I have a car at my place atm with a totally stock motor and quite adequate road performance with over 35" tyres. Sure, it is not as quick as a stock sierra, but the tyres/wheels weigh about double the standard ones. This is all due to gearing, in this case, narrow track diff gears (3.9:1) and a series 4 rockhopper.

Steve.

I agree totally with Steve.

You MUST keep the engine working within its torque range to take advantage of any mods you may do to it.