I have a 86 1.5L carburated crx that is sitting in my backyard, and all it needs is an exhaust system. (manifold, cat, and exhaust piping). My friend has a RHB5 turbo from a subaru sitting in his garage, would it be possible to rig up some sort of setup? I will do most of the custom work for the manifold and downpipe, but will try and use the junk yards for most of the other stuff. With the carburated motor, what will be my biggest problem in doing this?
I'm only doing this for the heck of it so not worried about presentation. Any help would be appreciated.

 

do a compression check first. carbourators are fine

 

Well its not quite that simple. You either have to install the the carburator before the turbo and draw the fuel through the turbo and intercooler(if you have one) which is supposively tricky to get the idle and run right. The other option is to build a pressure box around the entire carb so it will see the same pressure inside and outside of the carb otherwise the boost will push the fuel back into the carb and you will have serious fueling problems under boost and serious engine problems if you try to drive it like that. The only drawback to the pressure box is the floats and some of the other internal will collapse under the pressure in most carbs.

 

Best option would be a draw-thru setup; things are much different w/ carb cars, and I wouldn't really recommend it unless you're pretty set on doing this.

 

i ran a blow-thru carbed vehicle on the street for awhile... it wasn't a honda, but imho, it's not worth the effort.

if your '86 crx has one of the kelhuin(sp?) carbs on it, it's probably full of smog hoses and garbage... without putting it in a box, you'll almost certainly need o-rings around the throttle shafts at some point, on top of what everyone else has said.

there are also the similar fuel pressure problems with blow-thru carbs that you have with blow-thru efi... you must keep the fuel pressure ~3psi ahead of the boost, or you'll empty the carb bowl, run lean, and blow the motor.

draw-thru carbed systems are not good daily driver candidates because the fuel falls out of suspension real easily, it's a looong way from the carb to the head... you can't run an intercooler with a draw-thru setup because fuel puddling in the intercooler is a ticking time bomb... i've seen a couple of race cars do it, but it's definitely not an option for the street.

 

This is something that I really wanted to do with my 86 CRX DX too. After lots of research I decided that it just wasn't worth the effort. It is very difficult to turbo the DX and HF carbed CVCC heads because of the wierd auxiliary ports and valves. You have three basic options.

1) Stick it out and turbo the carbed motor. By all accounts this is a HUGE pita.

2) If it's the chassis that you really want to keep then your best options are to swap in either an 85-87 Civic/CRX Si head onto your block along with the complete fuel injection system (also a pita), or swap in the complete engine/tranny/ecu/suspension from one of those. If yours is an HF then I would definitely think about swapping in an Si tranny since the gearing is so much better. OR, you could swap in the engine/tranny/suspension/ecu from an 86-89 integra for more potential from the larger displacement and twin cams.

3) Fix the car, sell it, and buy a much better basic platform for boosting. That is what I did. Sold the 86 DX, bought an 87 Si. I've heard that the best one to look for is the 85 Si because it is lighter. Check out the links below and good luck with it.

http://www.usol.com/~carpaydm/Links/
http://www.redpepperracing.com/
http://www.redpepperracing.com...=2562
http://www.crx.org/links.php3
http://www.honda-acura.net/
http://www.homemadeturbo.com/
http://www.homemadeturbo.com/f...=3921
http://www.homemadeturbo.com/f...10498
http://d-series.org/
http://carolinahondas.com/foru...a93b3
http://pub161.ezboard.com/bbseriesalternative
http://www.thezcresource.com/m...index
http://www.theoldone.com/forum/default.asp

 

Thank you for the help, I guess I won't be trying to take on this project. I was thinking it wasn't going to be as hard but I guess it is. Well maybe I will work on some dual weber carbs or something.
Thanks again.

 

i did it with dellorto carbs... i have seen people run weber idf's on low boost settings without prepping the carbs for boost... under ~7 psi.

getting rid of the honda carb is a step in the right direction, check out this group for blowthrucarbed stuff: http://autos.groups.yahoo.com/group/blowthruturbo/

just remember to get a fuel pressure gauge!