eke_zetec_RWD Posted July 30, 2011 Share Posted July 30, 2011 anyone done this? escort had surge when building boost in higher gears and lowish rpm. or is there any other ways of getting rid of it? other than changing turbos? oh its a vf36 from a spec c sti. twinscroll ball bearing. looking at you kpr Quote Link to comment Share on other sites More sharing options...
kpr Posted July 30, 2011 Share Posted July 30, 2011 haven't ran into the problem myself. so not much help to you! other than swapping the turbo out. more head flow, cam timing, bigger exhaust housing for later spool, possible to ramp boost on slower with your boost control? 4age etc? also, ignition timing. if its low will be spooling the shit out of the turbo and cause issues Quote Link to comment Share on other sites More sharing options...
mjrstar Posted July 30, 2011 Share Posted July 30, 2011 I believe the anti surge cover will direct inlet air over the compressor blades at the correct angle of attack (great for high boost high rpm situations) but it sounds like your engine simply can't "eat" the air at the rate the turbo is producing it. In short I doubt you'll have any joy by going to an anti surge comp cover. Cam selection and cam timing is probably the easiest place to start. (other than asking the turbo to make less boost) I'm not familiar with that turbo but being twin scroll and BB it's likely to make a fair bit of boost pretty low down. Quote Link to comment Share on other sites More sharing options...
Hemi Posted July 30, 2011 Share Posted July 30, 2011 quite a few (dunno if in your application) have a bypass cloe to the compressor to stop this, recirculates the air from after the compressor to immediatly before it, i think you lose a bit of efficiency up top with it though? Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted July 30, 2011 Author Share Posted July 30, 2011 haven't ran into the problem myself. so not much help to you! other than swapping the turbo out. more head flow, cam timing, bigger exhaust housing for later spool, possible to ramp boost on slower with your boost control? 4age etc? also, ignition timing. if its low will be spooling the shit out of the turbo and cause issues it used to have a 8psi wastegate on it so i had the boost control (g4) in a 3d table to bring boost on slower at this rpm and then go up to 22psi at higher rpm. but it wouldnt hold 22 psi at high rpm as the spring wasnt stiff enough. so now i have a 1 bar acuator and have this issue now. its a pinto, big valve ported head. i have to tune it again so i can play with the cam timing to move the boost curve. or go to a bigger cam, it has a "turbo grind" from kiwi cams in it currently. i was thinking about maching the front off the turbo and welding in a 3inch inlet so i will have enough material to machine the anti serge ports in. there isnt alot of info around about the exact location of the grove in relation to the compressor wheel. i want to keep the turbo. they are used by all the top new subaru rally cars and are very reliable. Quote Link to comment Share on other sites More sharing options...
JoKer Posted July 31, 2011 Share Posted July 31, 2011 ..pop onto clubsub and have a yarn to steve murch.... just start same thread and see who pipes up Quote Link to comment Share on other sites More sharing options...
kpr Posted July 31, 2011 Share Posted July 31, 2011 ^ worth a go if no luck with anti surge cover. going to an external wastegate will give you better boost control. have ran solid 24psi on a 6psi spring. still bit of a band aid fix though. but bumping up the compression ratio and ramping on the boost could work well. more responsive and nicer to drive plus more progressive powerband. doing similar with my 4age at the moment, but due to excessive compression ratio. throwing more boost at it after max torque. (max torque where it wants to knock) which is resulting in a huge powerband Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted July 31, 2011 Author Share Posted July 31, 2011 sounds good, this motor is less than 3000km old. dont want to mess with it yet lol. external wastegate option would require two wastegates, one on each scroll. i can run lots more boost if i want more power, one dyno run on 32psi (up to 5000rpm) showed no knock what so ever and produced 232kw at 5000rpm, curve was still on its was up up up. Quote Link to comment Share on other sites More sharing options...
kpr Posted July 31, 2011 Share Posted July 31, 2011 sheesh maybe i should get a pinto. you could run a single gate, and make the pipes merge at the gate. with a divider that sits against the seat of the wastegate. effectively keeping the 2 scrolls separate till the gate opens. but yeh 2 would be better. what compression ratio is it running? sounds like bumping it up would be a good move anyway Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted July 31, 2011 Author Share Posted July 31, 2011 yea i thaught that could be a option. bloody escort engine bays are so small and cramped though. its 8.0:1 compression. on the low side. but still very responsive and economical. i dont really want any more power. its fast enough as is. just want to get rid of the surge. but pintos seem to be quite strong and revvy. pinto ae85? nah keep it in the family like you have. Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted August 6, 2011 Author Share Posted August 6, 2011 i pulled front cover off today, did some measuring and realised that if i inserted a 75mm front inlet the machining would brake into the outer scroll. so that means theres simple no room to allow a typical anti serge setup. so what i did may seem a bit backwards but i machined out the smallest part around the wheel by 0.4mm. effectivlly giving it more clearence between the wheel and the housing at the inducer end of the wheel. it seemed to help, most of the serge has gone, although there still is some. much better though. still pulled hard right through the revs. also finally made a radiator overflow can. tomorrow may see a oil breather can to get rid of the factory leaky filter/filler cap Quote Link to comment Share on other sites More sharing options...
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