Performance Vauxhall - - QUESTIONS & ANSWERS -

@ I’ve just fin­ished build­ing a Mk5 van but there are a few things I need to tie up. It’s a 2007 model with a Z20LEH, steel rods, high flow in­let, in­ter­cooler, ex­haust and a GT turbo and so on. It’s been mapped by a lo­cal lad and it’s strug­gling to make de­cent fig­ures. In fact, it’s a to­tal dis­ap­point­ment. It did 315bbhp and just didn’t seem to want to pull any harder and the lad pretty much shrugged his shoul­ders and said it was some­thing that I’d done wrong. I’m gut­ted as I was hop­ing it’d crack 350bhp eas­ily so any ideas on what to do? Cheers, Gavin.

AWe’d be in­clined to agree with you, 315bhp is far be­low what a good Gar­rett based set up can pro­duce so there is some­thing amiss. First, we’d per­haps ques­tion the map­ping skills. Given the rel­a­tively poor re­sults, we’d pretty much ex­pect any map­per worth his salt to be able to look at the data and ad­vise where the is­sue lies so with lit­tle feed­back, we’d rec­om­mend a trip to a rep­utable dyno and have the van checked over and fairly ur­gently as there could be some se­ri­ous fu­elling is­sues that could cause last­ing dam­age. Said is­sues could be down to a hard­ware is­sue or in­deed, the soft­ware which is why we al­ways preach that cheap ‘cus­tom’ map out­fits should best be avoided.

Be­yond this it would be pure spec­u­la­tion on our part but it’s worth con­sid­er­ing fac­tors such as the air flow me­ter, lambda sen­sor, the 2.5bar map sen­sor may be max­ing out (a 3 bar one with ap­pro­pri­ate ECU ad­just­ment would be bet­ter suited) and the in­jec­tors may be too big and in turn cre­at­ing a very rich mix­ture. There are sim­ply too many fac­tors for us to be able to pro­vide a de­fin­i­tive an­swer but we’d cer­tainly ex­pect fig­ures push­ing to­wards 400bhp us­ing a GT2871RS or sim­i­lar. There are nu­mer­ous Vaux­hall tuners out there, a quick Google search will soon re­veal those who are well re­spected so we’ll re­frain from be­ing spe­cific but any will be able to di­ag­nose, ad­vise and hope­fully round up those miss­ing horses for you.

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