Im in the middle of putting a turbo s4 engine with s4 turbo and exhaust manifold into my 90 convertible. I am going to use the s5 n/a harness . I have the s5 turbo intake manifolds, throttle body, fuel rails, afm, boost pressure sensor, ecu, front cover, and bov.

My main question is do I need to have a turbo bac valve, and run the air controll valve on the lim if running no emissions?

Do i also need to use the s5 water pump housing off of the engine i pulled out, or can i just use the s4 one thats on the engine currently?

I know its probably covered 1000's of times but i cant read through endless forums. Any info on this would be appreciated.

Thanks
Garth

 

Are you planning on running a aftermarket ems? I know when I disconnected my BAC valve the idle was not very good.

 

I was just going to use the stock ecu. i do not have a turbo s5 bac. i only have a turbo s4 one. i wasn't sure if it would idle properly without it, so i guess i need to buy one. Are the n/a ones the same as turbo if both s5? and if i use the ACV do i have to run an air pump, or is there no point since im not putting emissions on at this time.

 

No point in using the air pump on a turbo, even more so if you arent using emissions.

I believe you will want a S5 TII bac, people have gotten away without using one but i see no point in not having a bac.

Your going to want a water pump system from a turbo model because it has a coolant nipple on it for the coolant return line from the turbo. There is ways around this though.

 

I have the s4 turbo water pump housing. Think I could just use that housing. I'd rather not drill extra holes for the coolant. So I guess ill have to track down a turbo 2 s5 bac.

 

Kinda funny coz im doing a conversion as well using a complete 88.5 tii harness (thats right, from headlight to taillights) with streetported S5 tii motor, lim combined with S4 tii tb and such including AIC BUT not sure if i will use a stock s5 turbo or TO4. The other dilema, havent fully decided if this set up will go on a SA or RX-3. Headache

 

Sure is a headache. I just found out I shouldn't have removed the bolt in the front of the essentric shaft. I had to so I can swap the front cover. Kinda sucks, now I'm not sure if I should take off the cover behind that so I can check that bearing. Really don't want to do that, but I think I'd rather just buy a s5 short block lol.