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1st Edition ADandD
Aug 31, 2009
This seemed like it might be a little open-ended for the question thread. I'm running (or, well, about to be running) a small fast-spooling turbo (GT2860RS) with a small hotside on a relatively big (3.0) engine (because gently caress top end I want to build boost backing out of my driveway). Currently only set up for 8 PSI and no boost controller because I want to shake out bugs first, but unlikely to go past 10PSI in any case.

I'm inclined to take the wastegate signal from the intake manifold.

My thought is that the turbo's likely to spool up so fast that if I take the signal from right after the compressor, I'll start popping the gate before the intake manifold is under pressure (especially because the tubing run from compressor to wastegate is about 4".) My charge pipe right now is only about an 18" straight run of 2.5" silicone, so it seems like any backpressure shock from the throttle plate against the turbo isn't really going to be that big a deal (compared to someone who's running five feet of intercooler plumbing at 15+PSI.)

Does this make sense? Alternate suggestions?

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1st Edition ADandD
Aug 31, 2009
Really appreciate the responses, guys.

It's not a modern engine - it's a VG30E, lol. This turbo's actually about the same size as the ones on the stock 87-89 turbo models. Basically I am trying to recreate what Nissan did on the later z31s with the small early-on turbo, just with a technically better turbo at higher boost, higher compression to start (the engine is originally NA), a less restrictive exhaust setup (2.5" straight pipe right from the turbo back, no cat), and a few other minor supporting things.

My GT28 has a T3 exhaust housing - I have a .63 that fits it but I bought a .48 just to take the idea to its logical (and agreed, maybe too backpressure-y) conclusion first. The turbo's been relocated up top so if the .48 is choking out just too early I can upsize without any major downtime.

I've always run wastegate signal off the compressor housing up until now but I was wondering with the really small hot side, like I said, if maybe the intake manifold might be worth trying in this specific case. That said I have a 7-inch run from compressor to wastegate and from the mani it's about 20 inches. It's 15 minutes' work to change so I may try it both ways...


edit: typo

1st Edition ADandD fucked around with this message at 17:16 on Oct 4, 2014

1st Edition ADandD
Aug 31, 2009
It's off the compressor. Thanks guys. Intercooler will probably go on in the spring once everything else is sorted and running (car's running and has had a couple test drives but I have no downpipe, I'm just dumping from the turbo under the hood) and I may revisit destructo's suggestion...

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