Multiple sites for multiple businesses, interlinking & IP addresses

[evotsi]

I have two businesses that are in the same niche, but sell products from different manufacturers. The first business website, SiteA was started around 7 years ago and is doing really well in the search results for its main keywords. The second business website, SiteB, was just put up recently, but is also climbing in the search results for the same keywords. I also put up a news blog for SiteA at news.SiteA.

So my question is this: How will interlinking between the three sites help or hurt and does it matter if they are on the same server in the same IP group. The sites have 100% separate content, however as they are in the same niche they contain many of the same keywords in the content. I have fixed navigation on each site so the navigation links are shown on every page. SiteA links to SiteB and news.SiteA on every page. SiteB links to SiteA on every page. They are all on the same server and SiteA and news.SiteA are on the same IP.

[tedster]

They are all on the same server and SiteA and news.SiteA are on the same IP.

Taht being the case, I'd assume that Google already knows the sites are related. Interlinking will most likely neither help very much with Google rankings, but nor will it hurt unless you go way over the top. So I'd suggest you interlink to serve your human traffic.

[evotsi]

I took another look at the sitewide links and took off all of the ones that didn't seem relevant for the consumers. I have come under the impression that Google is smart enough to know when I am optimizing for a search engine or my customer so now I just optimize 90% for the consumer. Along those same lines would it be better to put the other sites on a different IP Class, or does it even matter?

[Robert Charlton]

A lot depends on the rest of the linking profile to each of the sites. If each of the sites has many inbound links from good quality, independent sources, you may do OK. If they're all from the same pages, you're likely to have trouble, even if you have just one link between the two sites.

[evotsi]

Both of the sites have great links from independent sources. SiteB was a competitor that we bought out. They were selling similar products on their site and have had an established business for the last 10 years. Basically SiteA is our main site and storefront where all of our business comes from and SiteB is more of a hobby to try out another manufacturers products in the market.

After having SiteB up for a couple of months everything is going perfect. For one major keyword both sites are on Page 1. For all of the other ones SiteA is Page 1 and SiteB is Page 3. Even where SiteA is on page 1 for a product's SKU SiteB sometimes show up (product pages on SiteB list the equivalent products from the SiteA manufacturer).

After looking through these forums it seems that if Google sees two related sites in the same niche it starts to treat them as one. What are the chances that as SiteB starts ranking higher SiteA starts dropping?