(1) What boost to run on new turbo? (2) Boost spike question

[Shpyder]

I finally got a REALLY sweet dual exhaust cat-back system. Its lamost like the pic I posted a while ago. 2.5".

I called up the guys who did my turbo. You may remember me posting about this wierd hybrid thing they had custom made. They really did make it, they are one of 65 shops in the entire USA with the crazy equipment, so I'm not saying they bullshitted me. The guy says, that with its "larger" 1.65" compressor wheel, this turbo can handle 25 psi, guaranteed Ok. Done.

My question is, with that kind of turbo, and stock internals and stock fuel system, how much boost can my engine take?

ALSO, how much damage occurs to when boost spikes to 22 psi before settling down to a set 17 psi. In short, can short and quick boost spikes that go over the intended set boost limit bust a nut in your engine/turbo?

Thanks.

(PS I ran 17 psi on this new exhaust and my car was so much faster.. I'm gonna post pics soon)

[kjewer1]

How much boost you can run isnt really the question, its how much airflow. But with the stock fuel system and no logger I wouldnt go over 16-17 psi. With a logger I doubt you'll find that you can go much higher. The injectors will be the limitng factor. When I used to run 24-25 psi on the 14b, I was using race gas, so it was enough (you lean out quite a bit). But barely.

Boost spikes are a function of the WG or MBCs inability to react quickly enough to rising boost. Therefore its much more common on small quick spooling turbos. Certain MBCs are famous for having spiking problems.

Since boost spikes normally happen at lower rpm when the turbo first spools, there is enough fuel system capacity available to keep things safe. But one potential problem is that it is also spiking during peak torque, or peak cylinder pressure, which makes knock likely. And that knokc you get for that short period of time can cause the ECU to pull timing through the whole gear, until you let of the gas and it resets timing. So even if the knock is "safe," it can still have a dramatic effect on performance. So in short, get rid of that spike. Good well known MBC/EBC, large stiff lines to connect it all, etc. There is a sticky on RKO that may give more tips.

[Shpyder]

Thanks Kevin. I'm running a pretty good MBC (JoeP) and I still get quick sharp spikes. Maybe its one of those famously infamous ones, haha.Time to read the sticky.