Hey gurus! I don't post a lot on here but I've had a good look around. I own a s15 silvia and I think the time has come that I begin my quest for more power! I'll start off by saying that ideally I'd like to not forge the engine (as I just don't have the workspace at the min) for this project, I've read on some posts that people are running around 400 (give or take) or even higher on a stock SR20DET (blacktop). Now I understand custom oil feeds, returns etc will be required and that's no trouble, so I have a setup in mind and I was wondering if you more knowledgeable people can tell me if this would work. I'd also like to go top mount so this is what I'm basing everything on! S15 Spec R SR20DET APR head studs Aftermarket head gasket (not sure which one is best) rocker arm stoppers Nismo 740cc injectors(possibly higher) Custom made top mount manifold (any suggestions, surely there's more than 6boost and APW) 45mm wastegate Custom exhaust system ( this is being made locally) z32 MAF Alloy rad SR20de throttle body Walbro fuel pump (I've already fitted this) Sytec AFPR 8 rated plugs Standalone DTA Ecu (mapped by a local tuner who is very very good on a RR) Custom welded hardpipe FMIC pipework Electric fans (deleting viscous) Some form of boost controller (haven't decided yet) AEM AFR kit (already installed and working) Probably some other little bits and bobs I have forgotten! poncams (I have no idea what these are, some form of aftermarket camshafts?) Now to the turbo.. I have several options and not sure which would be best for my setup. I'd like a decently sized one (as it will be on show) but I understand the larger the more lag so I'd appreciate any advice on turbos. Turbo possibilities: GT3071R 2971R 2867R Borgewarner EFR 7064 (whatever you guys suggest) Please take into account this is in the very very early stages and I'm doing my research at the min, but with a s15 silvia being my dream car I'd love it to have the power I'd like. I understand other things non engine based will have to be upgraded and they are in the planning (350z brembos/6pots, structual bracing, clutch, box, flywheel etc...) car is currently sat on BC Coilovers. Any advice (and even links to buy parts) are appreciated! Thanks a lot! (and I know I've probably missed a few things so let me know)
Z32 MAF is pretty old hat, for what they are they're expensive and prone to breaking. Z33 or R45 MAF's are cheaper and usually more reliable, since you're going standalone it doesn't matter what MAF you use, you could even go MAP. Don't get rid of the viscous fan or cowling if you can, it's the best setup. Why bother welding the FMIC pipes up?? Why do you need or want an AFPR??? Do you want 400BHP or do you want 400 now and more later? There's no point buying a 500BHP turbo and running it at 400, there's also no point buying a turbo for 400BHP and finding out you want 500BHP in a couple of months.
Thanks for your reply! Completely forgot I can go MAFless with standalone so thats the route i'll be taking. Welding the fmic pipes is something i've always done with previous cars and builds, less places for their to be a boost leak and it looks pretty! Call it habit or just personal preference. I'd run a AFPR to raise rail pressure to the injectors 1:1 so my AFR remains as stoich as possible (or whatever my target AFR is set in the ecu), it also gives me the ability to monitor fuel pressure on the gauge. I'd like 400hp now and more later, but ill take as MUCH as i can get right now. If 500 is achievable on stock bottom end, then I'd like 500hp now! I'm new to these engines so I have no clue about them really so this is all part of my research , are they strong enough for 500hp and high cylinder pressures? Thanks again for your reply!
500 is a step too far on a stock engine, 400 is about what you'd want to push it. Bin off the AFPR, not needed at all.
What clutch are you using for this build? It all looks fairly decent, best thing to do now is talk to the guy who's going to tune it and make sure he's happy working with it all. (Does the DTA system no offer boost control as part of the unit?) The exhaust builder is going to wanna see the turbo and wastegate obviously, so get those first.
I'd say a set of mild cams will make 400 more achieveable on a stock bottom end. Will give better power without running higher levels of boost.
A set of Tomei Poncams were on the list, I think the 256 ones are drop-in replacements and don't really need adjustable pulleys.
There are a lot more tried and tested ECU's that offer boost control and MAP sensor as well, Link ECU comes to mind and has a plug and play option for S15's (http://dealers.linkecu.com/NS15Plus). But agree that it comes down to what your chosen tuner is happy to tune. Also agree 400hp is max on stock internals and the max you'd want to put through a small case gearbox before going CD009 / RB25 gearbox But some 256 Poncams are what you'll be after, along with either a 2871 / 3071 or comparable BW/Holset
Clutch I haven't yet looked into, do you have any suggestions? Copper mix? DTA does offer boost control and as taken from thier website "Open or closed loop turbo pressure control via PWM valve. Modify target turbo pressure by gear selected. Modify target turbo pressure by vehicle speed. Two control maps selected by switch on dashboard. Active base PWM map for easy calibration. " My chosen tuner is most at home with a DTA ecu and hes been tuning them for the last 14 years. I'd be very happy at 400 and I think that's what I'm going to aim for. Holsets seem to be cheaper brand new than most turbos so I'm a little bit unsure on the quality of them. I think in my head i've decided to go for a 3071 but again I'm still unsure! But I have now already purchased my DTA ecu (yay) so that's 1 step closer to my goal!
There's a gigantic thread on here about Holset's. Have a flick through that before making a decision. I would not have any hesitation in running one, they are (IMO) the best bang for buck turbo out there. Any reliability issues come down to people not understanding their oiling requirements properly (unrestricted oil feed, 15mm+ ID oil drain), and performance issues result from people not allowing them to breathe sufficiently. As for clutch, you'll want 5 or 6 puck single plate with sprung centre (to lessen shock to your gearbox) and a pressure plate with a decently high clamping force. If you're going 5 speed you'll want to ditch your S15 dual mass flywheel and go S14 flywheel so look to grab one of those to suit S14 at the same time (along with your clutch) You could go twin plate to future proof a forged build and 500hp but it's a bit overkill for 400hp and a small gearbox
