spudly13 Posted January 30, 2012 Report Share Posted January 30, 2012 Hey guys this is my first post here on ratsun, and just for the record ive done lots of research and cant seem to solve my problem, so for those of you who are just going to say use the search bar....ive tried. So i went from an l20b blowthrough dual SU carbs to an l16 draw through setup... The l20b never ran quite right (carbs didnt like the air flow) and i eventually blew it up and decided to do it the right way. For the last week ive been building a motor, doing all my mock up and finally have it all put back together. Im Using a stock l16 (rebuilt) single carb intake manifold, stock cast head with a custom up pipe, a td04 turbo from an 06 wrx and currently ONE of my dual SU carbs... The Problems: Throttle response is slow and not always the same, the car is shaking and vibrating really bad (checked timing, good, checked spark compression and plugs all good), inconsistent idle, it will idle sitting in the shop but when i drive it its all over the place, over all its running like crap... boggy and feels like its missing almost Ill post some pics so you guys have an idea of what im working with, any help or ideas would be greatly appreciated. Thanks Casey Quote Link to comment
Digi7al Trauma Posted January 30, 2012 Report Share Posted January 30, 2012 Hey guys this is my first post here on ratsun, and just for the record ive done lots of research and cant seem to solve my problem, so for those of you who are just going to say use the search bar....ive tried. So i went from an l20b blowthrough dual SU carbs to an l16 draw through setup... The l20b never ran quite right (carbs didnt like the air flow) and i eventually blew it up and decided to do it the right way. For the last week ive been building a motor, doing all my mock up and finally have it all put back together. Im Using a stock l16 (rebuilt) single carb intake manifold, stock cast head with a custom up pipe, a td04 turbo from an 06 wrx and currently ONE of my dual SU carbs... The Problems: Throttle response is slow and not always the same, the car is shaking and vibrating really bad (checked timing, good, checked spark compression and plugs all good), inconsistent idle, it will idle sitting in the shop but when i drive it its all over the place, over all its running like crap... boggy and feels like its missing almost Ill post some pics so you guys have an idea of what im working with, any help or ideas would be greatly appreciated. Thanks Casey first off, i hope you arent running an intercooler... you sound like you know yourstuff, so i doubt it.... but im honestly thinking that on boost the su isnt able to provide enough fuel... ill check abit more on su's and turboing... but ill wait for pics b4 i say anything else Quote Link to comment
spudly13 Posted January 30, 2012 Author Report Share Posted January 30, 2012 No intercooler and fuel is my thought as well, or meybe its puddling and causing it to be inconsistent? Quote Link to comment
spudly13 Posted January 30, 2012 Author Report Share Posted January 30, 2012 stuggling with pictures, theyll be up soon enough Quote Link to comment
DISLEXICDIME Posted January 30, 2012 Report Share Posted January 30, 2012 when are you seeing full boost 4500rpm's that is a big turbo for a 1.6 sounds like fuel check out how Julian is running his fuel bowls http://the510realm.com/viewtopic.php?f=27&t=10313&start=330 what fuel pump ar you using . what is the pressure .it might be to high Quote Link to comment
spudly13 Posted January 30, 2012 Author Report Share Posted January 30, 2012 I was boosting 10 pounds with the l20 at about... well whenever i punched it so 2000rpm all the way up, The fuel pump is off the l20, stock mechanical Quote Link to comment
spudly13 Posted January 30, 2012 Author Report Share Posted January 30, 2012 Thanks for that link, i have another float bowl, i may give that a shot Quote Link to comment
DISLEXICDIME Posted January 30, 2012 Report Share Posted January 30, 2012 a stock mechanical fuel pump will not work in a turbo application you need the fuel pressure to raise 3 pounds for every pound of boost if i remember right. Quote Link to comment
DISLEXICDIME Posted January 30, 2012 Report Share Posted January 30, 2012 this should help you they had the same issue http://community.ratsun.net/topic/11154-daves-new-510-project-l-boosten/ Quote Link to comment
Logical1 Posted January 30, 2012 Report Share Posted January 30, 2012 a stock mechanical fuel pump will not work in a turbo application you need the fuel pressure to raise 3 pounds for every pound of boost if i remember right. Fuel Pressure is only a issue on 'blow through' or pressurized carbs as the float bowl is inside the +pressure box. As for the poor running, Thats a bit long of a run for the pressurized fuel/air and with length of piping it will act as a condenser for the fuel to re-liquefy before it enters the combustion chamber. For a draw-through system the closer you can get the output of the turbine to the intake the better. Anytime your pushing atomized fuel through a length of pipe it will re-condense. There was a dime at JCCS last year from autohero that has a nice SU turbo set-up if I can find the pics. Did you break-in/run the engine after building it with a standard carb set-up? Quote Link to comment
spudly13 Posted January 30, 2012 Author Report Share Posted January 30, 2012 I dont think that fuel "pressure" is a problem either, it was on my blow through and i had to pressurize the bowls, but in this setup i think your right. im going to have to shorten that pipe somehow... I did run the engine for a bit before slapping all this stuff on. didnt drive it just did a little break in to make sure everytthing was running right in the shop Quote Link to comment
DISLEXICDIME Posted January 30, 2012 Report Share Posted January 30, 2012 logical is right . can you re clock the turbo and shorten the charge pipe. and the intake pipe on the carb is a sharp angle you need a smoother transition Quote Link to comment
datzenmike Posted January 30, 2012 Report Share Posted January 30, 2012 Did you re-jet when going to a single carb? Going lean under boost will fry the motor in no time flat. Maybe get an a/f gauge so you can see what's happening Quote Link to comment
spudly13 Posted January 31, 2012 Author Report Share Posted January 31, 2012 i just re-clocked the turbo and am finishing up the new intake pipe. yes a fattened the carb up significantly, and it just so happens i have an a/f gauge in the mail!!! I am still going to try and shorten the intake at the carb into turbo as well. I should get it running in a couple hours. ill let you guys know what happens! Quote Link to comment
DISLEXICDIME Posted January 31, 2012 Report Share Posted January 31, 2012 here is how jason grey did it back in the day http://www.newprotest.org/projects/510/turbo_L.pl Quote Link to comment
spudly13 Posted January 31, 2012 Author Report Share Posted January 31, 2012 So heres what i came up with, let me know what you think. My charge pipe is about 10 times shorter and i managed to shave 3 to 3 1/2 inches off my carb to turbo adapter. Thanks again for the help i really appreciate it Ive read through Jason Greys article, i think im almost there! haha Quote Link to comment
Logical1 Posted January 31, 2012 Report Share Posted January 31, 2012 Nice work! Have you run it since the re-fit? If you do, pull one of the plugs while your waiting for the a/f gauge to get a ballpark of your mixture. Found some pictures of the other set-ups I have seen: I like the ground-up fabbing and the flow of this system, no harsh corners or internal flat spots for fuel to pool on. I like the ratty look of the dime and his home-brew turbo set-up, the charge pipe looks a bit long though. It also looks like hes using some coolant lines to warm the mixture pre-turbo I am currently fabbing my draw through system to mount on a stock 220 SU manifold directly from the output of my turbine, slow progress with all my other projects though... Keep us updated with your status! Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 That looks way better. If I might make a suggestion? Pipe in cold air from in front of the rad. The turbo and the compression concentrates the heat just like a diesel does. Under hood air isn't the way to go here. The cooler you can get or keep the air the more advance and or boost you can run without the risk of detonation. If this is to warm the intake charge I totally do not get this at all. Maybe winter non boost but otherwise.... Totally would be cool to use air conditioner to drop the intake air temp to near freezing. Quote Link to comment
banzai510(hainz) Posted January 31, 2012 Report Share Posted January 31, 2012 get ahold of Ray Stonehocker (lives in Bothell I think) Hes running a 1 SU turbo system Quote Link to comment
Logical1 Posted January 31, 2012 Report Share Posted January 31, 2012 If this is to warm the intake charge I totally do not get this at all. Maybe winter non boost but otherwise.... I'm curious as to this myself, I am only guessing as to the purpose. However its looks to me like those are coolant lines and even 5 min after starting the engine those lines are going to get fairly warm and heat the whole intake tube up. It would be cool if the owner of that dime was on here to chime in... Quote Link to comment
DISLEXICDIME Posted January 31, 2012 Report Share Posted January 31, 2012 The lines are to keep the carb from iceing Quote Link to comment
DISLEXICDIME Posted January 31, 2012 Report Share Posted January 31, 2012 The lines are to keep the carb/intake from iceing Quote Link to comment
datzenmike Posted January 31, 2012 Report Share Posted January 31, 2012 Those lines are behind the carb so can't be for carb icing. Won't matter much if the intake gets frosty inside or out it will still function. It has to be bloody cold and damp ti get frost to form. This warmed air would be fine in the winter to help with fuel atomization but should be set so that it can be turned off. Warmed air from the exhaust would be better and using the stock sensors it will shut off at full throttle. Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.