Tech

Zoom issue 149 – On Sale Now

Today I went out to see Alex from Plazmaman to get some intercooler pipes welded up for a tech story that shall be coming out in a  future Zoom. While I was there he gave me a quick look at the Plazmaman development mule, a Subaru WRX STi. The top-mount air-to-air intercooler was pulled off and replaced with a water-to-air intercooler.

As Alex points out there are many benefits of the W2A intercooler setup. The two main benefits are:

1) No massive intercooler to annoy the police and registration authorities. The W2A setup is relatively stealth.

2) It keeps the inlet charge at a consistent 30-40deg unlike air-to-air coolers that have massive temperature fluctuations depending on the conditions and driving environment.

Changing the size of your rims often means having to figure out what tyre size you need. The problem with changing the wheel size is that without getting the appropriate tyre size your speedo can be out of whack. Figuring out what tyre size you need to maintain the effectiveness of your speedo requires some basic maths. Here are a few online calculators for tyre size and other wheel measurements including offset.

One of the best is from Miata.net (Miata's are a USDM MX5). It has a nifty visual representation of the tyre versus wheel size for new versus old combination. Here is an example for my situation of wanting 20in rims on my BF XR6 ute:

Another site, Car Bibles, has a page of calculators for every conceivable calculation possible when it comes to figuring out changes in the wheel tyre combination, including offset.

Here is another calculator linked to an online tyre shop that lets you know if there are any actual tyres in the size you are after, which is very handy.

I am going to have rethink the wheel/tyre combination for my ute if I want to retain the load capacity.

We visited Andy Wyatt at Adaptronic as part of the big 30 page ECU feature in the current issue 147 of Zoom. He is doing the initial config on the monster VH45TT-powered R31 Skyline coupe built by Mark at MRC Dyno and Performance (that is just next door to Andy's workshop) and shows us how simple it is to adjust the injector timing in real time through the E1280s ECU's powerful tuning software.