Engine management and Holset turbo's

[STL SRT8]

First off I am new here and for the past month I have been doing nothing but searching about an S14 RB25 swap. I have learned everything I need to know on swapping and now I am playing with the idea of a top mounted Holset HX35. What injectors, engine management and other supporting mods am I looking at? I'm wanting to get into the 400 rwhp range with the engine. Another thing I am confused about is the MAF placement, some say blow through and others say Z32 MAF before the turbo. The last question I have is should you retain the recirculating bypass valve or use an aftermarket bov? I owned a WRX with a few goodies and it was alway best to retain the bypass valve unless going ubber huge turbo... lol

So any help to clear some things up will be greatly appreciated.

[240slidekat]

i guess it all depends on your engine management, like for instance safc doesnt really like non-recirculated bov. you can make it work but its a pain. 400whp your definately going to need injectors, and an engine management to control those injectors. my suggestion is get the swap done first before you start tinkering with other stuff, its a whole easier to troubleshoot because everybody know that swapping an RB is not exactly a walk in a park. There is always something not right. good luck.

[STL SRT8]

i guess it all depends on your engine management, like for instance safc doesnt really like non-recirculated bov. you can make it work but its a pain. 400whp your definately going to need injectors, and an engine management to control those injectors. my suggestion is get the swap done first before you start tinkering with other stuff, its a whole easier to troubleshoot because everybody know that swapping an RB is not exactly a walk in a park. There is always something not right. good luck.

Thanks! I haven't even bought the car nor the engine yet. I am doing all the research I can so that when tax season comes I am going to be buying the engine so I can work on it over the winter (new gaskets, water pump, timing belt... etc.) The car will be bought around next spring or summer and this will also take some time too since I would like to find a near stock unmolested 97-98 Kouki. This is just a build that is not going to happen over night, just something for me to spend time on getting it right and enjoy the time I have working on it.

Since I traded the WRX I mss the times I got to tinker with it and mod it. Also I miss owning a turbo car and have wanted a 240 for a VERY long time. I still have lots to search and read up on!

[STL SRT8]

Anyone else care to chime in? Also how would the stock internals hold up to an HX35? Should I look into new rods and pistons?

[bmadd2402]

hey, sounds like you are setting yourself up for success. Hang out a bit, there are a lot of people running holsets. one of the RB's weak points are the ring lands, so if you are doing a winter build, and have the money, think about pistons. It varys from car to car, some have problems and crack a land and some make 400rwhp and are fine. Oh and search crank collar and oil restrictor And if you do pistons, might as well do rods.

[STL SRT8]

hey, sounds like you are setting yourself up for success. Hang out a bit, there are a lot of people running holsets. one of the RB's weak points are the ring lands, so if you are doing a winter build, and have the money, think about pistons. It varys from car to car, some have problems and crack a land and some make 400rwhp and are fine. Oh and search crank collar and oil restrictor And if you do pistons, might as well do rods.

When buying pistons what should I look for? Stock compression or other? I plan on having the engine decked and cleaned so I guess I should go ahead and do new bearings, rods, arp studs, oem gasket set and pistons. I already know I will be using the Isis intake manifold and q45 tb and I suppose the Z32 maf with an Apexi filter, 555cc injectors, Walbro and a FPR. I have a shop local to me that can make my downpipe and I dont think I will have an issue fabbing up the ic pipes. I plan to use a 44mm wastegate that will be vented into the downpipe as well.

Using an HX35 what boost levels can I be safe using with some of the things I have listed? I still haven't found to much on the engine managment yet.

I really need to write all this stuff down somewhere... lol!

[STL SRT8]

As far as pistons go are the Wiseco forged pistons at 86.5mm (.020) a stock piston?

[eh?]

As far as pistons go are the Wiseco forged pistons at 86.5mm (.020) a stock piston?

No, if you don't deck the block the CR will be about 8:1, decked 8.4:1.

[STL SRT8]

No, if you don't deck the block the CR will be about 8:1, decked 8.4:1.

After reading some more I don't think I will have the deck blocked and the stock pistons I found out are 86mm. So I may just look into getting forged CP 86mm pistons and Eagle rods.

Now... how much boost should I be looking at with the Holset? 15-20lbs?