What you consider as a "stage 2"? I had ported head, polished exhaust ports, 3 angle valve seats/valves, poslished chambers, flowbenched.. This head has been capable to flow at least 700bhp, only weak spot is stock cams.
Edit: just saw, jou have 16vt. Friend pushed 6xx bhp from completely stock head with stock cams on 16vt (gtx35xx). He also pushed 200hp of nitrous extra
Last edited by Jopa_zgd; 22/11/201512:34.
Re: stage 2 head max power
[Re: gillan]
#1555823 22/11/201512:4322/11/201512:43
hi sorry my mistake its on my 20vt i leave my 16 standard. im hoping for 550 - 600 head is in being ported and polished etc ive told them to hang fire because im not sure about the valves?
Would any of you fit stronger valve springs or is the head in standard form good for revving.
my aim is to rev to 7800 and by the looks of what you have just said i can stick with standard valve sizes.
Re: stage 2 head max power
[Re: gillan]
#1555841 22/11/201517:4322/11/201517:43
Valves are definitely ok. Especially if you want mid range power. With bigger valves you will lose low rpm power and thorttle response. I was revving 7900 for some period, but stock cams were too "weak" for high rpms so tuner decrease rpm limit to 7600. If I remember correctly someone from this forum was revving 8250rpm on stock valvetrain without any problems.
But to be sure I will go for uprated springs, just if you miss the gear or downshift too early. Only ones I found available to purchase without custom ordering is: http://www.bar-tek-tuning.com/lshop,showdetail,17779,en,1426701443-17779,1107452820.fiat,030602053_019,3,Tshowrub--1107452820.fiat,.htm
Re: stage 2 head max power
[Re: gillan]
#1555870 22/11/201521:3122/11/201521:31
It's not the valve springs that are the first point of failure - it's the stock rods (torque) and rod bolts (more revs = more stress on the bolts) - if you search for 'Nyssa7' on here (going back a while!) you'll get some good info on rev limits on the 20VT engine.
Re: stage 2 head max power
[Re: gillan]
#1555942 23/11/201516:2023/11/201516:20
my bottom end is fully forged and balanced, ive also gone for uprated rod bolts for the extra strenght. all depending on revs and flow capability depends on my turbo choice with power band etc