Guest 73Turbo240z Posted June 8, 2005 Share Posted June 8, 2005 So my buddy and i were mocking up the L28 yesterday, were having clearance issues w/ the turbo we'd like to run (the T70 i have listed in the FS forum), the deltagate currently gets in the way. One of the options he threw out there was somthing he'd read about using positive pressure boost control... basically your BOV becomes your wastegate, venting boost out of the piping instead of on the exhaust side... He said from what he read and understood of it basically it will cause the turbo to pretty much sit spooled ready to rock most of the time, and that boosting positive would become instantanious to a degree... Thats all fine well and good, however i've never heard of this being real world application... anyone know more about it? Perhaps an article that's written on it? This type of boost modulation would solve my space issue... if it works... Quote Link to comment Share on other sites More sharing options...
Thumper Posted June 8, 2005 Share Posted June 8, 2005 One problem I see with this is if you are using the stock efi it will let air that went through the air flor meter out and your car would run rich during this time. Also it would have to be an electronic blow-off valve because all bov's that I have seen run off the difference in pressure and vacuum between the tb. Also it sounds like the turbo would be rotating at the fastest speed it could vs being limited at 15psi and spinning at a slower speed. So I would guess the turbo would wear out much quicker. Other than those it sounds like a good idea if you are running an aftermarket ecu, can rig up the bov to vent at certain positive pressure, and either you don't car about longevity of turbo or you can find a way to limit its rotational speed. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted June 8, 2005 Share Posted June 8, 2005 One problem I see with this is if you are using the stock efi it will let air that went through the air flor meter out and your car would run rich during this time. Also it would have to be an electronic blow-off valve because all bov's that I have seen run off the difference in pressure and vacuum between the tb. Also it sounds like the turbo would be rotating at the fastest speed it could vs being limited at 15psi and spinning at a slower speed. So I would guess the turbo would wear out much quicker. Other than those it sounds like a good idea if you are running an aftermarket ecu, can rig up the bov to vent at certain positive pressure, and either you don't car about longevity of turbo or you can find a way to limit its rotational speed. yea alot of variables to be had, as you know the car will be on MSnS after the breaking period if i can ever lay hands on a factory EFI setup. So theres the bypassing of the AFM, could keep it out of boost till then... lol things would be so much easier if that stock turbo i had hadn't been all buggered up. I don't particularly like the idea, the whole premiss behind it makes me feel like it would be a thermal nightmare with things always being primed like that, fast i'm sure, but fast to wear out also... someone sell a stock T3 so i can just puts around to get this damn thing broken in! Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted June 8, 2005 Share Posted June 8, 2005 i've never seen this.. i could be done.. BUT i wouldnt recommend it.. go out.. and buy a good external wastegate.. =) save ya the trouble.. or buy a used T3.. like on eBay right now Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted June 8, 2005 Share Posted June 8, 2005 i've never seen this.. i could be done.. BUT i wouldnt recommend it.. go out.. and buy a good external wastegate.. =) save ya the trouble.. or buy a used T3.. like on eBay right now *edit* found it... The T70 w/ its deltagate would rock hardcore... just not enough room w/ this motors intake/exhaust manifold setup... Quote Link to comment Share on other sites More sharing options...
TimZ Posted June 8, 2005 Share Posted June 8, 2005 *edit* found it... The T70 w/ its deltagate would rock hardcore... just not enough room w/ this motors intake/exhaust manifold setup... If I could fit a 60mm HKS gate with a T64, you ought to be able to fit a deltagate (it's probably not big enough for a T70, btw). Did you look underneath the turbo? All kinds of room there... The pop-off valve schemes were tried early on, and were largely abandoned for the wastegate setup. Problem is that by regulating via a leak on the compressor side, you are putting the compressor out of it's high efficiency envelope and forcing it to put out hotter air right when you need it the least. This type of setup works best with low boost applications (or as a safety backup) - presumably not what you would run a T70 for. Also, I don't think you'll see an advantage in spoolup times - the wastegate is closed when you are off boost and cracking pressure issues would be similar for either setup. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted June 8, 2005 Share Posted June 8, 2005 If I could fit a 60mm HKS gate with a T64' date=' you ought to be able to fit a deltagate (it's probably not big enough for a T70, btw). Did you look underneath the turbo? All kinds of room there... The pop-off valve schemes were tried early on, and were largely abandoned for the wastegate setup. Problem is that by regulating via a leak on the compressor side, you are putting the compressor out of it's high efficiency envelope and forcing it to put out hotter air right when you need it the least. This type of setup works best with low boost applications (or as a safety backup) - presumably not what you would run a T70 for. Also, I don't think you'll see an advantage in spoolup times - the wastegate is closed when you are off boost and cracking pressure issues would be similar for either setup.[/quote'] the deltagate mounts on the exhaust housing of the T70... and where the mounting point is, the deltagate is forced right into the intake manifold... i'm sure theres plenty room south, we just arn't pointing the right direction unfortunately... :- we'd looked into making a T3 to T4 adapter plate that would clock the turbo 15 or so degrees further out from the engine to see if it could clear that way, but that's still a ways off... Quote Link to comment Share on other sites More sharing options...
TimZ Posted June 8, 2005 Share Posted June 8, 2005 the deltagate mounts on the exhaust housing of the T70... and where the mounting point is' date=' the deltagate is forced right into the intake manifold... i'm sure theres plenty room south, we just arn't pointing the right direction unfortunately... :-[/quote'] That doesn't sound like anything a blockoff plate, a wastegate flange, some schedule 40 pipe and a welder couldn't solve... Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted June 9, 2005 Share Posted June 9, 2005 True... how many times should one re-engineer the wheel though ya know? I think what we've worked out is that i'm going to run my a stock T3 for the break in on a ceramic exhaust manifold i have, and that should give me the time i need to fabricate the other manifold with it's T4 + remote mounted deltagate... now i just have to see if turbonetics or deltagate make a block off plate for that application. the manifold i picked up was originally setup for a turbo wise wastegate... which i found out retailed @ it's lowest for $500... freaking insane! Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted June 9, 2005 Share Posted June 9, 2005 dude chris here in houston, well was in houston was using one BIG T4 with a deltagate and he was having the same problem. he found a spacer and something else that i forgot and it fits fine now.. mike Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted June 9, 2005 Share Posted June 9, 2005 I've seen cars bleed boost from the charge side of the turbo before, but those cars where making over 1600hp and boosting more thean 35psi. Not to mention the boost controll systems and efi where state of the art. Anyhow, that probably would be overkill for your situation. Sounds like you for sure need some big time fabrication skills or maybe reconfigure the turbo set up. I have some T3 exhaust hosings that fit a TO4 exhaust wheel that I use often on Z cars. Should give you a some more space. I have .81 and .70 size. Just one more questiong.....why are you running a T70 anyways? Maybe be a stupid question but not alot of cobinations are set up for a 700HP turbo. Good luck. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted June 9, 2005 Share Posted June 9, 2005 I've seen cars bleed boost from the charge side of the turbo before, but those cars where making over 1600hp and boosting more thean 35psi. Not to mention the boost controll systems and efi where state of the art. Anyhow, that probably would be overkill for your situation. Sounds like you for sure need some big time fabrication skills or maybe reconfigure the turbo set up. I have some T3 exhaust hosings that fit a TO4 exhaust wheel that I use often on Z cars. Should give you a some more space. I have .81 and .70 size. Just one more questiong.....why are you running a T70 anyways? Maybe be a stupid question but not alot of cobinations are set up for a 700HP turbo. Good luck. cars being setup for top end pulls so we wanted somthing that we'd not hit the ceiling on in terms of boost... Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted June 9, 2005 Share Posted June 9, 2005 Very interesting. Quote Link to comment Share on other sites More sharing options...
Clifton Posted June 9, 2005 Share Posted June 9, 2005 If that had a .68 or .70 I would be interested. I just made an adpater for someone else to run a T series (T66 ect) sized turbo with external WG off the stock manifold. I still have some flanges and could do another. The Tial style WG's have a much smaller diaphram housing than the Deltagate. You would be fine running a 35mm one on there. I haven't had any boost control issues running one Even at 30 psi. Quote Link to comment Share on other sites More sharing options...
drzed Posted June 10, 2005 Share Posted June 10, 2005 I run an APV (Absolute Pressure Valve) or blow off valve or whatever you want to call it. It is my only method of controlling boost pressure and it works fine for my application. My setup is part of an old BAE / Rayjay setup from the late 70's. The Rayjay turbo is an EE80 which is about equal to a T4 I believe. This method is both good and bad. It is very simple - has only one moving part and almost nothing to go wrong. Boost pressure is increased by changing springs (or shimming). I have no boost creep or other problems as some others with wastegates do. The bad part is as mentioned before - turbine speed could get out of control if the system is not sized appropriately. My Rayjay has a very large A/R of .80 It does not start to spool till over 3000RPM (under foot braking) and isn't all in till way over 4000 RPM. Driving down the road these numbers would be more like 3500 and 4500. It wouldn't be my first choice for a control but it will work just fine under certain conditions. My car is an auto and mostly used for drag racing and spirited street driving. I run an SDS so the "leaking air" isn't a problem. I've been running it for 1 1/2 years now and it really pulls hard - best run of 11.49@116. Quote Link to comment Share on other sites More sharing options...
Guest ZFetsh Posted June 12, 2005 Share Posted June 12, 2005 Ooo, no, don't use you BOV to control boost - you'll probably overspool the turbo, which would lead to a premature death.Another option would to get an internal wastegate version of the turbo - Garratt now makes the GT3076 (capable of up to 500hp) with an internal wastegate Quote Link to comment Share on other sites More sharing options...
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