laney Posted June 30, 2014 Report Share Posted June 30, 2014 A blow off valve is another word for a dump valve, the things you hear going off when you back off the throttle on a cosworth or subaru... the ptissshhhhh sounding things.....Internal wastegate pressure pipe normally comes off the boost side of the turbo on the up pipe somewhere.. Link to comment Share on other sites More sharing options...
El Gringo Posted June 30, 2014 Author Report Share Posted June 30, 2014 Cool, thanks Laney All the turbos i've looked at have a waste gate actuator on the actual turbo itself with a short feed hose from the side of the compressor housing, do i need a dump valve of can it be done through the waste gate? Cheers Link to comment Share on other sites More sharing options...
Superdunc Posted June 30, 2014 Report Share Posted June 30, 2014 The waste gate is on the exhaust gas side it is opened by boost pressure. When the boost is where you want it, the waste gate opens allowing exhaust gases to bypass the turbine, modulating the boost. Fit a stronger spring to the actuator, and it will take more boost to open it, so the engine will see more boost. You can also fit a bleed valve to the signal line from plenum to the actuator, this means the actuator sees less boost then the plenum.The problem with having just a pipe between the plenum and actuator is that the waste gate starts to open before the desired boost is reached. If you use an electronic boost controller, it will only send the signal pressure to the actuator once the pre-set boos is reached.A dump valve is fitted on the compressor side of the turbo, it only opens when the throttle is shut. A vacuum pipe down stream of the throttle butterflies actuates it, allowing boost pressure to vent to atmosphere, or recirculate into the air filter. It's purpose is to stop the compressor stalling, and keep it spinning longer to reduce lag when you get back on the gas. Link to comment Share on other sites More sharing options...
El Gringo Posted June 30, 2014 Author Report Share Posted June 30, 2014 Ah i understand now, thanks Dunc So rather than just taking the actuator feed from the turbo housing its better to take the boost reading from the plenum through a bleed valve to ensure the waste gate stays closed until the boost pressure in the plenum is right rather than boost pressure at the turbo. Link to comment Share on other sites More sharing options...
El Gringo Posted June 30, 2014 Author Report Share Posted June 30, 2014 So more like this? Link to comment Share on other sites More sharing options...
laney Posted July 2, 2014 Report Share Posted July 2, 2014 Looks good to me, Ive always taken the boost gauge feed from the inlet manifold, after the carbs, so you can get a vacuum reading on the boost gauge when the throttle is shut. Ive never done anything with the vacuum readings though but at least the gauge is working properly...!! Link to comment Share on other sites More sharing options...
El Gringo Posted July 2, 2014 Author Report Share Posted July 2, 2014 Ah that makes sense Now all i need to do is work out what size turbo i need Might give this a whirl and see what comes out http://www.squirrelpf.com/turbocalc/ Link to comment Share on other sites More sharing options...
El Gringo Posted July 3, 2014 Author Report Share Posted July 3, 2014 Right, i've bought my self a book on the subject, I shall do some research and report back Link to comment Share on other sites More sharing options...
laney Posted July 4, 2014 Report Share Posted July 4, 2014 I think the best way to go about it is do enough research so that you have a vague idea of what you are doing, then its trial and error after that...!! Link to comment Share on other sites More sharing options...
El Gringo Posted July 4, 2014 Author Report Share Posted July 4, 2014 I think the best way to go about it is do enough research so that you have a vague idea of what you are doing, then its trial and error after that...!! Haha you're right Laney Does seem to be the way everyone else operates. My vague is just a bit too vague at the moment, but eventually you've just got to get stuck in Link to comment Share on other sites More sharing options...
El Gringo Posted July 11, 2014 Author Report Share Posted July 11, 2014 I think I've narrowed it down to either a Garret GT12 or the IHI RHB31 Both are as small as you can get, using the squirrel performance calculator on the GT12 puts all the points inside the compressor map just about, so none on the surge side, it'll just run out of puff at the top which I guess is about all i can hope for. However the GT12 is the smart car turbo and has the cast manifold which make it a no go i think. The Ecotrons small turbo/The Chinese one YZ listed earlier should move it more into the suitable range being a bit smaller. I'm still trying to get my head round compressor maps but i think that these are the best options. Its always going to be a compromise so i'd rather have it with less top end boost rather than in the surge area. Will have a go at plotting the points on the RHB31 Map and see where they come out Link to comment Share on other sites More sharing options...
El Gringo Posted July 11, 2014 Author Report Share Posted July 11, 2014 Right i've plotted the points on the RHB31 map and its massively too small for the peak boost, so we're back to a GT1241 or a GT1511 which is probably a bit big Link to comment Share on other sites More sharing options...
El Gringo Posted July 11, 2014 Author Report Share Posted July 11, 2014 Compressor maps here http://www.squirrelpf.com/turbocalc/index.php?version=4&target_peak_power=100&pr_ref=14.7&engine_disp=0.4&engine_disp_factor=0&target_af=12&bfsc=0.5&max_ic_loss=1.7&rpm_redline=13500&rpm_peak_power=10600&rpm_max_boost=7500&rpm_min_boost=3000&vol_1=89&vol_2=93&vol_3=90&vol_4=87&vol_1=89&vol_2=93&vol_3=90&vol_4=87&intake_temp_1=90&intake_temp_2=120&intake_temp_3=135&intake_temp_4=140&turbo_n=1&map_sel0=18&map_sel1=19 http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.7&pr3=2.34&pr4=2.34&pr5=2.34&pr6=2.34&pr7=2.34&airflow0=0.4&airflow1=1.5&airflow2=4&airflow3=7.9&airflow4=9.2&airflow5=10&airflow6=11.7&airflow7=12.8&product_id=18 http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.7&pr3=2.34&pr4=2.34&pr5=2.34&pr6=2.34&pr7=2.34&airflow0=0.4&airflow1=1.5&airflow2=4&airflow3=7.9&airflow4=9.2&airflow5=10&airflow6=11.7&airflow7=12.8&product_id=19 Link to comment Share on other sites More sharing options...
CMSMJ1 Posted July 12, 2014 Report Share Posted July 12, 2014 What is a compressor map? Some sort of range of puff versus speed of exhaust? Link to comment Share on other sites More sharing options...
El Gringo Posted July 12, 2014 Author Report Share Posted July 12, 2014 Its the ratio of air volume flow vs boost pressure The points you plot are for the engine, at various rpms, the compressor map is the roundy line bit which shows the areas the compressor will work in, from which you can see if its sized correctly. I think..... Link to comment Share on other sites More sharing options...
El Gringo Posted January 11, 2015 Author Report Share Posted January 11, 2015 So more like this? Right, a bit more research done. I'm typing this up as much for me as you guys but if someone could sense check my thoughts it would be much appreciated. Assuming the above is reasonably correct, I've got a bit more of an idea of what i'm going to do. 1. I've decided on a GT1241 turbo, i think from my previous compressor mappings this was the one to go for. 2. The waste gate actuator on the GT12 is set for 7psi operation as stock - that's fine for me to start with, then I can use a bleed type manual boost control on a signal line from the plenum to the actuator. 3. The Blow Off Valve will be fitted in the up pipe - I "think" that this also takes its feed from the plenum so it see's boost pressure under load and then vacuum when you're off the throttle - which is what actuates it - at what point this occurs I'm still unsure. 4. Boost Gauge - Signal from the manifold side of the carbs to show boost and vacuum - can this be taken from the plenum instead? 5. Fuel Pressure Regulator - Everyone seems to use the Malpassi type so i will do the same, this takes a boost signal from the Plenum I think. 6. Fuel Pump - This I'm a bit hazy on, my book says that I need to maintain 4 psi (I've seen 5 and 6psi online) above boost pressure - so I assume if I want to run it at the 7psi boost that the wastegate will allow it to run to before it opens, I will need a pump that can provide at least 12-14psi? 7. Pitot tube - there are a lot of variables with this that I've seen but from what I can gather this is connected to the float bowl overflows - this means as the dynamic boost rises in the up pipe it pressurises the float bowls to prevent the fuel being blown back down the jets. Size wise i've seen 6mm per 25mm of up pipe diameter - I'm looking at 35-38mm for the up pipe so I reckon 8mm will be a good starting point. Assuming I get bored of the 7psi boost, I can use the manual boost controller to ramp up the plenum boost by limiting the boost seen at the WG actuator - again I assume that the fuel pressure required will need to be 4-6psi above the pressure i'm seeing in the plenum at this point. Does any of that make sense? Link to comment Share on other sites More sharing options...
Superdunc Posted January 11, 2015 Report Share Posted January 11, 2015 Right, a bit more research done. I'm typing this up as much for me as you guys but if someone could sense check my thoughts it would be much appreciated. Assuming the above is reasonably correct, I've got a bit more of an idea of what i'm going to do. 1. I've decided on a GT1241 turbo, i think from my previous compressor mappings this was the one to go for. 2. The waste gate actuator on the GT12 is set for 7psi operation as stock - that's fine for me to start with, then I can use a bleed type manual boost control on a signal line from the plenum to the actuator. Yes, but an electronic boost controller will be better. although the waste gate is set at 7psi, it will start to creep open before that boost pressure is reached. An electronic boost controller will only let the wategate actuator see the pressure signal once the pre-set boost is reached. Not essential to start with but consider it when planning the system. 3. The Blow Off Valve will be fitted in the up pipe - I "think" that this also takes its feed from the plenum so it see's boost pressure under load and then vacuum when you're off the throttle - which is what actuates it - at what point this occurs I'm still unsure. The vacuum signal for the blow off valve should come from the engine side of the throttle butterflies, when you shut the throttle the vacuum generated opens the blow off valve venting the boost pressure and preventing the compressor from stalling. This means you'll get much quicker response when you get back on the throttle. 4. Boost Gauge - Signal from the manifold side of the carbs to show boost and vacuum - can this be taken from the plenum instead? I would take it from the plenum. 5. Fuel Pressure Regulator - Everyone seems to use the Malpassi type so i will do the same, this takes a boost signal from the Plenum I think. 6. Fuel Pump - This I'm a bit hazy on, my book says that I need to maintain 4 psi (I've seen 5 and 6psi online) above boost pressure - so I assume if I want to run it at the 7psi boost that the wastegate will allow it to run to before it opens, I will need a pump that can provide at least 12-14psi? 7. Pitot tube - there are a lot of variables with this that I've seen but from what I can gather this is connected to the float bowl overflows - this means as the dynamic boost rises in the up pipe it pressurises the float bowls to prevent the fuel being blown back down the jets. Size wise i've seen 6mm per 25mm of up pipe diameter - I'm looking at 35-38mm for the up pipe so I reckon 8mm will be a good starting point. Assuming I get bored of the 7psi boost, I can use the manual boost controller to ramp up the plenum boost by limiting the boost seen at the WG actuator - again I assume that the fuel pressure required will need to be 4-6psi above the pressure i'm seeing in the plenum at this point. Yes, plenty of pumps that can so this Does any of that make sense? Link to comment Share on other sites More sharing options...
El Gringo Posted January 11, 2015 Author Report Share Posted January 11, 2015 Crackin'! Thanks Superdunc! Does the overall gist of what i'm proposing make sense? For the various plenum signals I had thought about trying to build a manifold with multiple boost signal outlets into a section of the plenum, does that sound ok? Link to comment Share on other sites More sharing options...
El Gringo Posted January 13, 2015 Author Report Share Posted January 13, 2015 Right, I've gone back over my compressor maps for the GT1241 and the RHB31 (which is pretty much a VZ21), I'm fucked if i know which one is the best option or if i've even plotted the points correctly. I found a different website that allows you to generate a table of air mass flow against different boost pressures, which i have roughly plotted on to the 2 maps. The RHB31 is most efficient at a lower boost of 11psi but the GT1241 is more efficient higher up at 18psi and less so at lower boost. Neither of them appear to be dropping into the surge area, and both are within the map islands at 11,000rpm, max rpm being around 13,000. Neither of them suit the high revs really - At 6500rpm (and 11psi) which i think is about max torque the RHB31 is producing about 50hp and at 10,400rpm which is quoted max power its about 85hp so a good 25/26hp up on standard At 6500rpm (and 18psi) which again is max torque the GT1241 should be producing about 64hp ish and again at 10,400rpm should be making around 100/110hp which is pretty good over the standard 59hp This of course is complete theory and unlikely to occur - i ask myself, will the engine hold together at 18psi boost? Also how do you get it to 18psi boost when the waste gate is set to open at 7psi? Is that purely down to restricting the actuator signal so its seeing less. I've no idea what i'm doing now and have made myself more confused. Link to comment Share on other sites More sharing options...
El Gringo Posted January 13, 2015 Author Report Share Posted January 13, 2015 I'm going to redo them a bit more accurately but it's one or the other....... I'm probably going to go for the GT1241, more boost Link to comment Share on other sites More sharing options...
fabiostar Posted January 13, 2015 Report Share Posted January 13, 2015 have you looked at the turbos used on toyota glanzas? Link to comment Share on other sites More sharing options...
El Gringo Posted January 14, 2015 Author Report Share Posted January 14, 2015 I'm struggling to find a compressor map for a CT9 turbo Link to comment Share on other sites More sharing options...
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