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Discussion Starter · #1 ·
Hey all, new to this forum and came in search of some info and suggestions on my recent project build. Got this 97 DelSol Si fitted with a D16Y8 for free from a buddy (score!). Has some rust being a PA car, and some other body work issues, but overall not bad, only 97k on it too! Story on it, an older gentleman that owned it got it stuck in a shallow creek and blew the clutch and pressure plate apart trying to get out, craziest thing I ever seen, got so hot the ring gear separated from the flywheel. Anyways, I've always wanted a Honda to build so I decided to dive in deep on this. Pulled the motor and trans out, tore the block all the way down. Had it sent off to a local machine shop for them to make sure the block and everything else was okay, then had it cleaned and honed. I got a set of the SpeedFactory no-notch long rods and 75mm YCP/Vitara pistons. I had them do all the ring filing and make sure everything was in good spec. Put the engine back together with just about every maintenance item I could do, new bearings all around, seals, gaskets, water pump, oil pump (shimmed and ported), timing belt, ARP head studs, OEM Honda head gasket, blah blah blah the works. Essentially a brand new motor at this point. So my question is this, PA inspections in my county test for emissions via the OBD2 port, for the time being, can I run this engine on the stock ECU with the slightly higher compression? I think SpeedFactory advertised a bump from the factory 7.8:1 to 8.8:1. I figured a higher octane would help, but is there anything else I should do to ensure it doesn't blow up or something? I would like to swap over to an OBD1 ECU with some bigger injectors and get it tuned down the road, but I need it to pass inspection first. This is my first engine build, I've done loads of research and taken my time on everything, but I've had conflicting info about running it. I was on another forum and asked about it, all I got was "your sh*tty car is gonna blow up" Very helpful indeed! I'm no expert, I don't claim to be, just looking for the right things to do to ensure the reliability and longevity of the engine. Thanks in advance!
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BATSLOMAN GIVES NO FUCKS.
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its a stock rebuild. stock ecu and gas is cheap
 
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Discussion Starter · #4 ·
That's what I was thinking. The only reason I did the rods, pistons, and head studs was that I was planning on adding boost down the road. The shop that did the machine work said they set the p2w clearance that would support, but still be okay for N/A use in the time being. I guess a good middle ground, I trust them, they build fast cars lol. Besides the tiny compression increase, it's still stock per say.
 

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Discussion Starter · #8 ·
Yea. Y8 in factory form is like 9.6:1, you're safe running factory ECU since everything else is pretty much stock as well.

Looks good! More pics?
Huh, interesting, maybe SpeedFactory has some incorrect info then. Either way, brings the pistons flush with the top of the block. Can't be that big a difference, and thank you! I have a couple, mostly engine shots. I have an original as well. I'm relieved to hear that it'll be okay as is.
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Huh, interesting, maybe SpeedFactory has some incorrect info then. Either way, brings the pistons flush with the top of the block.
That Speedfactory spec is contrasting what compression would be when using the dished turbo vitara pistons on stock length rods vs using their custom length rods.

What their spec is saying, is that if you used a stock length rod with the turbo vitara dished pistons, your comp would be roughly 7.8:1

Using their longer rod with the same vitara turbo dished piston yields roughly 8.8:1

The stock D16Y8 pistons have less dish in comparison to the turbo vitaras, and the compression height of the stock piston is taller than the vitaras, putting the stock rod/piston combo at 9.6:1.

I guess your actual static compression ratio depends on the type of YCP pistons you've purchased, they can be had in many flavors. Are they dished tops or wedge tops? If dished, they are the typical turbo spec, and coupled with the Speedfactory rods will yield you your 8.8:1. If the pistons are wedge design using the Speedfactory rods, you need to rethink your compression ratio lol. With the wedges, your most likely in the high 12's, low 13's.

So as rob said, if you are using dished vitaras with the Speedfactory rods and not boosting right away, technically you've lost static comp ratio and some power. Not really a bad thing, but if your pistons are the dished type, you have nothing to worry about using a stock ECU.
 

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Discussion Starter · #10 ·
That Speedfactory spec is contrasting what compression would be when using the dished turbo vitara pistons on stock length rods vs using their custom length rods.

What their spec is saying, is that if you used a stock length rod with the turbo vitara dished pistons, your comp would be roughly 7.8:1

Using their longer rod with the same vitara turbo dished piston yields roughly 8.8:1

The stock D16Y8 pistons have less dish in comparison to the turbo vitaras, and the compression height of the stock piston is taller than the vitaras, putting the stock rod/piston combo at 9.6:1.

I guess your actual static compression ratio depends on the type of YCP pistons you've purchased, they can be had in many flavors. Are they dished tops or wedge tops? If dished, they are the typical turbo spec, and coupled with the Speedfactory rods will yield you your 8.8:1. If the pistons are wedge design using the Speedfactory rods, you need to rethink your compression ratio lol. With the wedges, your most likely in the high 12's, low 13's.

So as rob said, if you are using dished vitaras with the Speedfactory rods and not boosting right away, technically you've lost static comp ratio and some power. Not really a bad thing, but if your pistons are the dished type, you have nothing to worry about using a stock ECU.
Ahhh, I see, makes sense then. Yeah they are dished flavor, 8.8:1 it'll be then. Thank you for the info guys!
 
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