Quote:
Originally Posted by RalliartRsX
Also, to add to this
1) What about those manifold that although are TS, have the two dump tubes merge to one to negate the price of twin piping, twin gates, etc?? Do those inhibit wastegate flow or is is insignificant enough that for a majority of the setups, its a very minor issue??
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if you run a single WG on a twinscroll setup, the inner tubes must be fully divided to retain all the twinscroll benefit. Typically the difference from a dual-EWg twinscroll vs a single-EWg twinscroll is 300-400rpm spool. Fabricated single-EWg manifolds, with dividing walls will almost always crack at the divider (especially on drift or road race cars) hence the reason FR does not do this. With regards to the EFR wastegate tube, it is cast as a divided section and is aerodynamically optimized, so it does not have the stress risers or thermal stresses that a welded/fabricated part would (will not crack.)
Quote:
Originally Posted by RalliartRsX
2) Also, you can simply change out the canister for a proper one from Turbosmart.
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the turbosmart IWg's are great actuators, and excellent spring selections. just be aware you can not give it much preload
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Originally Posted by Mannykiller
I don't know if it'll be as apparent on rotaries......but Honestly although BW is leading development... I still don't trust the internal WG as much as I'd trust dual External units. Funny though. Piston motors usually runner much higher boost levels than rotaries. Rotaries utilize much larger exhaust A/R's than piston motors. Rotaries can use the larger A/R's just as efficiently as Piston motors. Yet Rotaries generate more exhaust gas volume. I'm wondering if the Internal Wastegate EFR's will favor piston motors in terms of boost control just because they generate less exhaust gas volume. I just don't see an IWG EFR holding say 25-30lbs on a two rotor solid enough. I'm building a long runner turbo manifold for my external 1.05 EFR8374. I'll only be running 20lbs of boost on E85 and 14lbs on 91 Octane/race gas. But I'm building the long runner with the best possible Wastegate placement in order to hold boost as solid as possible everywhere...from 2500 all the way up to 8900 if I want. I'll keep you guys updated but I expect great things from this turbo with the high exhaust gas volume!
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from a theoretical standpoint - the best wastegate is no wastegate. if your concern of not holding boost up top occurs, its because the turbo is too small or the A/R is too small. Not because of the IWG.
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Originally Posted by Def
You've got it all wrong - IWGs control high boost easier. Low boost on a "large" engine needs lots of flow area. High boost is cake to hold, especially if you're not going to run really high turbine inlet pressures - which rotaries do not tolerate at all (which is why people run huge A/Rs and deal with lazy spool and run low boost). The BW EFRs have plenty of WG flow area to run >15 psi or so on a reasonably sized engine, and even low boost on most engine sizes as well. You just need the proper spring rate WG canister and the proper amount of WG canister preload. IWGs do have issues - on piston engines with a "small" turbo on an engine it's keeping the boost up when the turbine inlet pressure rises and forces it open. But that's almost a problem of too much valve area for your WG canister pressure/preload. A lot of the IWG problems you see are there are because people are stupid and do things like run 0 mm preload on the WG canister rod then complain of lazy boost pressure (minimum preload is 2 mm, something like 4-5 mm is more reasonable).
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great post... too bad you dont drive a subaru, some of the clowns on nabisco could benefit from your explanations.
Quote:
Originally Posted by Def
I still think IWGs do offer some compromises in boost control (really have to get your canister spring pressure in the right range) - but they can be worked with when they have enough flow area and canister spring pressures to chose from - which the EFRs do.
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one more thing to consider: traditional IWG canisters are a boost actuated device whereas the traditional EWG are vacuum actuated devices. an External-WG is fully sealed on the "close" side, but leaks on the "open side". Conversely the 2-port turbosmart or forge actuators are exactly the opposite. They are fully sealed on the "open" side, but leak on the "close side" <<let me know if this makes sense??>> - the conclusion i drew from doing a ton of WG testing - was that an external WG (which has a leaky bottom port) would function similarly to a 2port vacuum actuated canister (with similarly leaky bottom port). long story short: I am suggesting that exh manifold backpressure is what opens the valve on a traditional EWG (considering the bottom port leaks down so much.).
I have turbosmart sending their latest variation of 2 port IWG to me to try out but I am still unsure if we can do exactly what we need, will be interestign to find out
Quote:
Originally Posted by LuckyX2
Stiffest spring or go home  |
Quote:
Originally Posted by Mannykiller
Gtx turbos are great. But fact is that they're just not as light as the EFR wheels. Response really is night and day difference. I was skeptic when Geoff from full race told me about the EFR's...but after seeing dyno vids and charts with back to back differences... it really is night and day.
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agreed, the garrett turbos are a known quantity - proven reliable and will fit many existing installations. Garrett is selling a ton (and profitably) so there is not much reason for them to change... However the EFR's reduction of rotating mass in half, combined with a high end ceramic ball bearing are 2 major features that are difficult to overcome with traditional GT infrastructure
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Originally Posted by LuckyX2
the real advantage to EFR's is the Ti-Al turbine, that's one thing Garrett can't touch.
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Quote:
Originally Posted by Def
The GTX stuff ranges from just ok to pretty good IMO. Some of their wheels don't really put up good results for the overall response/spool IMO (GTX2867R comes to mind... the entire GTX30 lineup as well). I think most of this is using pretty old turbine technology and only being able to get so much out of a billet wheel that offers a bit more flow for a little higher RPM and slightly lower inertia of a cast wheel.
The main thing that really makes sense on the EFRs is that a twin scroll turbo setup starts to financially make sense vs. a single scroll. The IWG adds very little cost next to the cost of a full EWG manifold + 2 good external gates and fabbing dump tubes.
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agreed! this thread has some great info in it, keep it going