twins questions?

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Aug 21, 2003 | 07:40 PM

parish8

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From: omaha ne

twins questions?

thinking BIG here, like twin t-66's, got a few questions about twins.

2 wastegates right? how do you keep them perfectly in sync or does it matter? seem like one side would start bypasing the exhaust sooner than the other if they werent perfectly in sync.

are wastegates adjustable for any presure? lets say i want to run 6psi in street mode and 18psi in race mode, can i just adjust them? i know they have electronic boost controlers, how well do they work?

since there are 2 turbos i assume you size the waste gates for just 1/2 of the hp?

i will be running an auto and ball bearing turbos, i dont see "needing" a BOV, i will either be racing a full 1/4 mile or racing from a roll but i will never be going from WOT to 0 throttle to WOT quickly. i know BOV's keep the turbos spooled up when shifting and i dont need that. how hard is it on the turbos or throttle plate if you dont have a BOV and should i have one for the turbos reliability sake? for the price of a BOV(relatively cheap) should i install one or is it just a waste of money?

Aug 21, 2003 | 08:18 PM

y2khawk

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From: Olmsted Falls, OH

Re: twins questions?

Quote:

2 wastegates right? how do you keep them perfectly in sync or does it matter? seem like one side would start bypasing the exhaust sooner than the other if they werent perfectly in sync.

Yes, 2 gates. You basically need to use the same size spring in each one, and make sure they have the same preload on them. You can use a hand held vac/pressure pump to make sure the valve opens the same distance on each one for the same applied pressure.

Quote:

are wastegates adjustable for any presure? lets say i want to run 6psi in street mode and 18psi in race mode, can i just adjust them? i know they have electronic boost controlers, how well do they work?

Most externals have changeable springs, and secondary ports for a boost controler. They way i do it, and prolly your best bet with that range of adjustment is to run a manual controller (basically a dial pressure regulator). Put small springs in the gates, like 3 or 4 psi, and use the regulator to raise the boost. If you go with a large sweep requlator, like 15 to 20 psi, you will have from the base spring setting to the regulator max plus the spring pressure worth of adjustment. A light spring will give you better control and faster spool.

Quote:

since there are 2 turbos i assume you size the waste gates for just 1/2 of the hp?

You can't really be too big on a gate, but you can be too small. And you should size the gate for your low pressure setting. Since the gate is open more at the lower boost levels, if you wanna swing from 6 to 18 get a gate that can bypass enough to keep the boost down. Boost creep is bad

Quote:

i will be running an auto and ball bearing turbos, i dont see "needing" a BOV, i will either be racing a full 1/4 mile or racing from a roll but i will never be going from WOT to 0 throttle to WOT quickly. i know BOV's keep the turbos spooled up when shifting and i dont need that. how hard is it on the turbos or throttle plate if you dont have a BOV and should i have one for the turbos reliability sake? for the price of a BOV(relatively cheap) should i install one or is it just a waste of money?

Even with an auto you will have full boost at WOT to 0 throttle. Everything you do it, it slams against the turbo. It's not so much to keep the boost up on the shifts but to minimize the thrust loads on the bearings when you have huge amounts of air that has no where to go.

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