Some rebuild advice on a turbo build i picked up - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

redfogo · 07-31-2020, 10:28 AM

I picked a project 240 motors was ran lean had detonation issues. Still checking everything over but I had a few questions. Car has DSM 450cc injectors + T25 turbo + z32 maf + safc. No idea if PO just got greedy and blew the motor but to me this combo seems like plenty of fuel to have decent AFRs. Maybe the guy just advanced the timing to much no idea...

Im not looking for mad power so i wanted to keep everything and run a new block and keep stock ecu and add fuel where needed with the safc. Normally i like to use a standalone and tune myself a lot more easy for me no guess work. I wanted to try a budget build for once so looking for advise on this combo. Any one have any insight if this set up is reasonable or what I should do moving forward on this rebuild?

zombiewolf513 · 07-31-2020, 11:43 AM

Welcome.
Moving forward is only based on your determination and wallet. It sounds like you know you need to dive into diagnosing the issue. You probably want to go over the harnesses and make sure the safc is wired right and that the injectors are getting proper signals. Injectors could be clogged or a fuel pressure issue or a vacuum issue or your plugs are gapped wrong, your ignition timing or cam timing could be off, could be the tune.. It could be a lot of things. Sometimes you just gotta go over everything like a doctors physical and make sure its all good (enough).

NukeKS14 · 07-31-2020, 01:20 PM

What motor?

What 'blew'? We talking cracked ringlands or window in the block?

Your first clue to what happened is the safc. The maf signal influences a lot of parameters in the tune, timing included. Without a method of retarding timing with boost, youre really playing with fire. If you really do your own tuning you know this.

I would never skimp on engine management. Your options may depend on first answer. Im having good success on megasquirt for my KA.T. if you want to reduce cost you could build your own ms or go w/ nistune or some other daughter board based system.

If the motor is a KA, the rings arent gapped right for boost from the factory. I don't care how awesome the tune is, when you start turning up the wick on a KAT you are on borrowed time with the stock ringlands/ring gaps. You can get away with more on the stock pistons if you pull them and give a little more gap on the rings but why not just do proper forgies at that point?

Kingtal0n · 07-31-2020, 02:44 PM

If your goal includes a stock T-25 (Or T-28) I would just use a 100% OEM original sr20det engine and forget the injectors maf and safc all together

07-31-2020, 10:28 AM	#1
redfogo Join Date: Jul 2020 Location: USA Posts: 1 Trader Rating: (0) Feedback Score: 0 reviews	Some rebuild advice on a turbo build i picked up I picked a project 240 motors was ran lean had detonation issues. Still checking everything over but I had a few questions. Car has DSM 450cc injectors + T25 turbo + z32 maf + safc. No idea if PO just got greedy and blew the motor but to me this combo seems like plenty of fuel to have decent AFRs. Maybe the guy just advanced the timing to much no idea... Im not looking for mad power so i wanted to keep everything and run a new block and keep stock ecu and add fuel where needed with the safc. Normally i like to use a standalone and tune myself a lot more easy for me no guess work. I wanted to try a budget build for once so looking for advise on this combo. Any one have any insight if this set up is reasonable or what I should do moving forward on this rebuild?

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07-31-2020, 11:43 AM	#2
zombiewolf513 BANNED Join Date: Mar 2011 Location: AZ Age: 33 Posts: 1,682 Trader Rating: (6) Rides Gallery: zombiewolf513 Feedback Score: 6 reviews	Welcome. Moving forward is only based on your determination and wallet. It sounds like you know you need to dive into diagnosing the issue. You probably want to go over the harnesses and make sure the safc is wired right and that the injectors are getting proper signals. Injectors could be clogged or a fuel pressure issue or a vacuum issue or your plugs are gapped wrong, your ignition timing or cam timing could be off, could be the tune.. It could be a lot of things. Sometimes you just gotta go over everything like a doctors physical and make sure its all good (enough).

07-31-2020, 01:20 PM	#3
NukeKS14 Zilvia Member Join Date: Apr 2019 Location: KS Posts: 221 Trader Rating: (1) Feedback Score: 1 reviews	What motor? What 'blew'? We talking cracked ringlands or window in the block? Your first clue to what happened is the safc. The maf signal influences a lot of parameters in the tune, timing included. Without a method of retarding timing with boost, youre really playing with fire. If you really do your own tuning you know this. I would never skimp on engine management. Your options may depend on first answer. Im having good success on megasquirt for my KA.T. if you want to reduce cost you could build your own ms or go w/ nistune or some other daughter board based system. If the motor is a KA, the rings arent gapped right for boost from the factory. I don't care how awesome the tune is, when you start turning up the wick on a KAT you are on borrowed time with the stock ringlands/ring gaps. You can get away with more on the stock pistons if you pull them and give a little more gap on the rings but why not just do proper forgies at that point?

07-31-2020, 02:44 PM	#4
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	If your goal includes a stock T-25 (Or T-28) I would just use a 100% OEM original sr20det engine and forget the injectors maf and safc all together