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Discussion Starter #1
As stated, do i need to spec bottom end clearances at the loose end of the service limit or beyond to start off with a thicker oil and not spin bearings?

Looking to run thicker oil because im gonna be at full boost really quick with a td04 13c and low rpm power is harder on oil film.

Will eventually run 10-12 psi so thats quite a torque hit at 3k where the boost starts kicking butt.

Y7, bore tbd, daily driven, stock fuel cut

Oil will be cooled at 190, so is this discussion even needed?
 

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Never finishes (TWSS)
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I like to run 0.002-0.003" on the mains and 0.001-0.002 on the rods. And if you are running thicker oil your pressue will probably stil be above oem presure even with the extra clearence.
 

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If you are using an oil thermostat block to keep temps inline, you have less to worry about than most.

Honda initially had the 96-00 cars on regular 5w-30 oil, but then changed it to accept 5w-20.

Id probably just run 10w30 or 10w40 if you are concerned, and just let it warm up for a minute prior to any driving in cool temps.
 

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Discussion Starter #4
Man i just am not finding too many stock piston and rod builds for boost most ppl just send it w 180k or go vitara.

If the hot number stays 30 im gonna run closer to the middle low end of the established specs and not push it. Ill be happy w more like 180 hp instead of shooting for 195 or 200 w it.
 

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Meat Popsicle
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I’m running .002” mains and about .0018” rods, shimmed and ported Endyn OEM pump, and I run 15w-50 Mobil 1. I see about 55PSI at cold idle and around 15PSI at hot idle. Still well below OEM pressures but I feel like it’s still good enough.
 

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Discussion Starter #6
My rebuild budget just crept towards a vitara build but i think ill spend extra money on oem parts and an endyne oil pump like you have instead and come in under budget. Sad fact is, I have more projects than money and garage space. If i hit 160+ and its still a good car to drive around mileage wise w the td04-13c and 560 cc ev14s then the next project gets a shot.

What do ring gaps for a turbo build look like compared to stock?

Im basically just gonna stock rebuild it with arp fasteners and then gap/clearance it for boost. Ill probably run a bit tighter than you but probably not by much. ....or stockish as discussed if xw30 stays the preferred oil.
 

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Discussion Starter #8
Because my goals are modest enough that i believe stock parts with a good supply of clean 190 degree oil set up with tolerances to help it live under persistent low key boost will provide a long life and meet my goals.

If i did a vitara build yall would laugh at my 155-190 hp dyno runs anyway. I dont dig the powerband of many turbos approaching/over 300 hp so really id be doing a vitara build to MAYBE make 265hp tops. 215 or so maxing the efficiency limits of my current turbo.

Thats just not worthy of a build that could hold 375hp all day imo.

If yall come up w good reasons im wrong speak up. My mind is open to persuasion on the matter.
 

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Discussion Starter #9
After seeing the parts side by side its getting built up w vitaras
 

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Meat Popsicle
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Why anyone would use vitaras, even with custom length rods, is beyond me.

Why would you want such low compression when there are other OEM style cast pistons that would put you in the 9.6:1 range?
 

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don't need to figure it out ..

more cushin for the pushin ,

I think 7.5:1 compression is perfect for a reliable boosted pump gas notec .

but I also believe small turbos break engines..
 

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MuthaFuckaUppa
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Z6 Vitara with a TD04L off a WRX. Clearances were slightly more than Honda specs on the pistons clearance, the rest were to spec.

 

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MuthaFuckaUppa
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16 psi probably when I took that photo and when it was dyno'd, which was not easy to do, or smart.
Before I pulled the motor, which I still have sitting in the garage in a engine bag, I had it at about 18 psi. Piston tops look fine.

TD04 is a decent turbo for a daily single cam, I have a twin flap TD05 EVO8 turbo I was going to replace the TD04 with, but the car was wrecked.

I cut the flanges out at work on a CNC laser, I still have some Subaru flanges.
 

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Meat Popsicle
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don't need to figure it out ..

more cushin for the pushin ,

I think 7.5:1 compression is perfect for a reliable boosted pump gas notec .

but I also believe small turbos break engines..
that’s the part I don’t understand. Lower compression and higher boost or higher compression and lower boost. Same effective compression ratio both ways right?

Why does low compression make an engine safer? I’d argue that it doesn’t. If your tune is solid, high compression and boost is no riskier than low compression and boost.
 

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I think super low compression is completely and utterly useless when performance is the goal.


You have to run the turbo harder to achieve anywhere near the same PEAK performance, let alone the massive downfall of off-boost performance and spool time.


11:1 running a T25 at 10 psi will shit all over a 7.5:1 running a T25 even at 25 psi.
 

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Discussion Starter #17 (Edited)
Ok, thats a valid point. Id love to run compression like that given each psi would add more power than at 7.5:1 for obvious reasons. Heres the deal though. I have enough budget for a bore and fresh build, and either a good oil pump from endyne or sf no notch rods and pistons.

Being its a y7 i wont spin it hard. That makes beefy heavy parts ok imo and avoids the "vitaras crack at the pin" issue. I also dont care about peak power as long as i get the usable torque and longevity i desire and can pass people. Hitting 14s would be awesome but im not stuck on numberz.

Additionally this is my first efi honda tuning experience, last one was on carbs. It is also my first turbo tuning experience so ....low compression makes me feel safe when many people (even in this post) seem to believe small turbos and quick boost break motors.

Margin of error is what im equating compression to and honestly im not even sure i wont swap heads or throw something milled and mildly ported on it after its been up and running for a while.

But for now, my brain says build in a margin of error and run the build good for 400hp at half of that and itll last a while and have some headroom if i get bored 20k down the road.

Eh?

Anyway thanks for chiming in guys
 

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Lower compression doesnt really make it much safer, other than during a dyno pull back to back when you are pushing ignition timing and trying to find your upper limit for power.

Understandable you want your first experience to be free of rods searching for a weak block to punch through.


Take it easy, and at least with low compression, you can push ignition timing further and can get some room to play with for daily driving.
 

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Why anyone would use vitaras, even with custom length rods, is beyond me.


I think super low compression is completely and utterly useless when performance is the goal.


You have to run the turbo harder to achieve anywhere near the same PEAK performance, let alone the massive downfall of off-boost performance and spool time.


11:1 running a T25 at 10 psi will shit all over a 7.5:1 running a T25 even at 25 psi.
All of the above. It'd be such a dog of a motor, even if you pump massive boost through it and get decent numbers.

I'd try and keep the CR around stock.
 
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