karmagedon Posted June 8, 2009 Share Posted June 8, 2009 sorry, semi OT, but anybook by A. Graham Bell is very worth the read. That dude knows his shit about tuning and performance. In regards to turbo's here are some books I have read and would recomend : Forced Induction Performance Tuning Maximum Boost Link to comment Share on other sites More sharing options...
Ke36 Posted June 8, 2009 Share Posted June 8, 2009 when the internal gate sucks basically. So if im maxing out a turbo for what its capable of producing in my case a standard Rb25 turbo at 212kw, is it likely that the standard internal wastegate wont be up to it? I only ask as the computer & engine i have now was dynod for that figure, the only difference was that he had an external wastegate of the exaust. Im keen on going back to internal wastegate to keep things simple and get a better turbo in with less play at the same time. Cheers boe having only read this last page power isnt what causes overboost issues its flow usually a hi boost hi power figure wont cause any boost creep/spike issues as most of the exhaust flow is getting directed through the turbine wheel anyway so the internal is able to flow the relatively small (if any) amount of air it is required too its when you want low boost levels from a setup that can flow (exhaust etc) much higher numbers that an issue seems to arise for some info that youl like to here as it realtes directly to the turbo ur using the rb25 turbos dont seem to have much of an issue, have had a fair few number of mates with 3 inch dump pipes running around 12psi -14psi (which is close to the max for the ceramic wheels) and the internal gates where solid as a rock as opposed to the likes of the early evo turbos which overboost shockingly with a 3 inch dumppipe Link to comment Share on other sites More sharing options...
kpr Posted June 8, 2009 Share Posted June 8, 2009 when the internal gate sucks basically. So if im maxing out a turbo for what its capable of producing in my case a standard Rb25 turbo at 212kw, is it likely that the standard internal wastegate wont be up to it? I only ask as the computer & engine i have now was dynod for that figure, the only difference was that he had an external wastegate of the exaust. Im keen on going back to internal wastegate to keep things simple and get a better turbo in with less play at the same time. Cheers boe shit answer. but try it and see. if it doesn't work it isn't that bigger deal to put an external gate on afterwards. you could always hit the waste gate hole with a die grinder, before you put it on to improve chances of it working. Link to comment Share on other sites More sharing options...
Mick Doohan Posted June 8, 2009 Share Posted June 8, 2009 if it was me .. id look for what others have done in the same ballpark as you and check there results there is nothing more vital to a upgrade or conversion than doing your research and knowing the solutions to problems you haven't encountered yet personally i know of a couple of these pulling that sort of numbers with a non modded turbo ... you just have to be a little careful as the nylon compressors tend to melt Link to comment Share on other sites More sharing options...
forced Posted June 8, 2009 Share Posted June 8, 2009 sorry, semi OT, but anybook by A. Graham Bell is very worth the read. That dude knows his shit about tuning and performance. He's the bloke who invented the telephone. They didn't have turbos back then, not on telephones anyway. as opposed to the likes of the early evo turbos which overboost shockingly with a 3 inch dumppipe The evo problem is caused by the outlet pipe off the turbo being badly designed where the wg and turbine flows join together. Steve Link to comment Share on other sites More sharing options...
SHGWAG Posted June 9, 2009 Share Posted June 9, 2009 Just a quick point for steve, you have said that under if you are running "low" boost, a BOV is not needed? Why is this, and why then do all of the factory turbo cars that I have seen run BOVs? Furthermore, A mate of mine was running a 4A-GTE on 6 psi & it had chronic compressor surge. When it comes to the positioning of the BOV, if you look at most reputable aftermarket I/C, intake / compression tube kits, the BOV is always located closer to the throttle plate rather than the turbo. Maybe someone more knowledgeable will hazard a guess as to why this is?? Link to comment Share on other sites More sharing options...
kpr Posted June 9, 2009 Share Posted June 9, 2009 so air doesnt go backwards im guessing. Link to comment Share on other sites More sharing options...
Brock-Lee Posted June 9, 2009 Share Posted June 9, 2009 why would the air go backwards. its not as if its a giant conga line of air molecules. Link to comment Share on other sites More sharing options...
Simon Posted June 9, 2009 Share Posted June 9, 2009 The pressure wave must go backwards. It makes sense to have the bov at the throttle cos thats where the air will become compressed first as all the other air in the pipe comes crashing against the closed plate. Link to comment Share on other sites More sharing options...
Brock-Lee Posted June 9, 2009 Share Posted June 9, 2009 ^yuh, but the amount of that that the turbo is pumping out when the throttle snaps shut is normally fairly large. the time difference will be negligable between the pressure being X psi and the same pressure further away from the throttle EDIT: tbh, I dont think it makes much difference as to where the blowoff valve is placed. plumb back ftquietness Link to comment Share on other sites More sharing options...
Simon Posted June 9, 2009 Share Posted June 9, 2009 ^Thats what i was just thinking too. Was thinking how little difference the inertia of air would make with pressures. Should ask my dad. He owns a workshop with half dedicated to turbochargers lol. Link to comment Share on other sites More sharing options...
kpr Posted June 9, 2009 Share Posted June 9, 2009 you know what i mean. bov close to throttle flow carries on in same direction. plus you'l get a hi pressure area at the throttle plate when it snaps shut. end of the day is just a hole to let out excess pressure. its location hardly of great importance, compared to the rest of the turbo setup. / too slow. will go with hi pressure at throttle plate part Link to comment Share on other sites More sharing options...
Spencer Posted June 9, 2009 Share Posted June 9, 2009 Just a quick point for steve, you have said that under if you are running "low" boost, a BOV is not needed? Why is this, and why then do all of the factory turbo cars that I have seen run BOVs? Furthermore, A mate of mine was running a 4A-GTE on 6 psi & it had chronic compressor surge. real surge isnt going to happen on most properly sized engine turbo combos, go look at the surge line on a compressor map. The turbine needs to be driving the compressor with some force for surge to occur all that happens when the throttle snaps is compressor slow down. As i said theres countless race and factory cars with out them you think their shafts split in half as suggested previously? My soarer didnt run one turbos still in mint condition. If it worries you run one, location isnt a issue Link to comment Share on other sites More sharing options...
Ke36 Posted June 9, 2009 Share Posted June 9, 2009 heres a big disscussion on ausrotary bout running no bov http://ausrotary.com/viewtopic.php?f=16&t=17113 Link to comment Share on other sites More sharing options...
Gaz Posted June 9, 2009 Share Posted June 9, 2009 when the internal gate sucks basically. So if im maxing out a turbo for what its capable of producing in my case a standard Rb25 turbo at 212kw, is it likely that the standard internal wastegate wont be up to it? I only ask as the computer & engine i have now was dynod for that figure, the only difference was that he had an external wastegate of the exaust. Im keen on going back to internal wastegate to keep things simple and get a better turbo in with less play at the same time. Cheers boe Your turbo you have will be fine with internal wastegate, if it had one! What boost is that engine tuned for? Your turbos let down will be its comp wheel which shouldn't be boosted over around 12-14psi. Im not sure what model RB25 turbo you have but if you choose to sell and buy another RB turbo I would wait around and try get a 300zx T25. From what I know they are the same specs as the RB series(unsure which RB turbo or if there is a differance) turbos but with a steel wheel which will allow you to boost over 14psi if thats what you wish. But if your engine is tuned at 200+kw at treads now at say, 7psi, then you still have plenty of room to play. If you buy another turbo and choose to run internalk gate HKS make an aftermarket actuator for that turbo. I think this is just the equivilant of a stronger spring in an external gate. Now a question: Has anyone had experiance with mounting a wastegate directly off the rear housing? I,e making a new hole and welding a flange on. I know its cast. Gaz Link to comment Share on other sites More sharing options...
My name is Russell Posted June 9, 2009 Author Share Posted June 9, 2009 It would be something along the lines of getting something like this http://www.trademe.co.nz/Browse/Listing ... =222511907 then modifying a wastegate to go on her and plumb back into the exhaust? Im thinkings? Link to comment Share on other sites More sharing options...
Gaz Posted June 9, 2009 Share Posted June 9, 2009 Thats just to use with internal wastegate. You dont have a dump pipe at the moment and prob will end up getting one made. Because of this reason then you could run a wastie on the dumpipe like the old owner did. Unless of course there is some reason not to like sealing issues. That guy who you got a quote for to make manifold will be able to make dump pipes. A 3" one is what most people with those turbos go for, weather this is the right choice or not is another storey. Gaz Link to comment Share on other sites More sharing options...
Hemi Posted June 9, 2009 Share Posted June 9, 2009 Thats just to use with internal wastegate. You dont have a dump pipe at the moment and prob will end up getting one made. Because of this reason then you could run a wastie on the dumpipe like the old owner did. Unless of course there is some reason not to like sealing issues. That guy who you got a quote for to make manifold will be able to make dump pipes. A 3" one is what most people with those turbos go for, weather this is the right choice or not is another storey.Gaz im gettign confused ... whats the use of having a wastegate after the turbine?? Link to comment Share on other sites More sharing options...
Brock-Lee Posted June 9, 2009 Share Posted June 9, 2009 the stock wastegate flap is removed and so all hes doing is moving the wastegate diphragm further away from the engine, It is still bleeding off pressure from infront of the turbine wheel Link to comment Share on other sites More sharing options...
Hemi Posted June 9, 2009 Share Posted June 9, 2009 the stock wastegate flap is removed and so all hes doing is moving the wastegate diphragm further away from the engine, It is still bleeding off pressure from infront of the turbine wheel im confused now Link to comment Share on other sites More sharing options...
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