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Old 01-16-2013, 06:21 PM   #1
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Default Need Help Building a 350-400hp engine!!!! Bearing clearances and ring gap

Ok guys you all will mostly reconize my 2jz swap miata. I am currently working on another project while I am waiting on my intake manifold and some other small parts for that car.

First off I must say this is not a miata but the information will translate and I think it will be helpful to many people. I have searched google and tons of forums high and low but I still need help.


I have built a few motors in the past mostly mild to stock rebuilds that dont need much other than plastigauge and send it out. In this case I am building the following engine, and I want it to be right.

I am building a Ls Vtec Turbo setup capible of making a reliable 350-400 WHP.

The engine is as follow-

B18a Block cleaned and honed using a good non blown up engine
B16a head with Delta custom cams stock valves freshened us with new seals and a lap job.
wiseco 11.5:1 forged pistons
Eagle forged rods
Sock crank
Fully balanced rotating assembly including clutch setup and balancer pulley.

OEM GSR oil pump new
OEM gsr water pump new
Gates timing belt
baffled stock b18 oil pan

Turbo setup is as follow-

Precision GT3076R
Turbosmart 38mm gate
Synapse BOV
2.5" precision intercooler
2.5" piping
Walbro 255



Anyway you all get the idea I know you are not honda guys but here is my problem. I am building a motor to hold high compression and boost and I want to drive this car a lot I am building it like a DD so i can trust it to go anywhere. I have read tons of threads and the clerances people run are all over the place some people recomend stock others recomend a little looser or a lot looser. I want to know what the engine builders out there think.

Stock rod and main clearances are .0017-.002


Ring gap from wiseco's website I figured the following

top ring -.018

second ring - .020

My current thinking is to run the clearances for rods and mains at .0018-.0019 and I may go a little looser on the ring gap just to be safe.

Please let me know what you all think dont flame for being a honda this is a reasonable engine build and I wanna get it right the first time around. I do not expect this engine to last to 200K but I would like to get 50K out of it at before having to rebuild it. Any input will be appreciated
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Old 01-16-2013, 06:29 PM   #2
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You do know you will be more than 11.5:1 cr with that set up... and a turbo?

Hope you are running E85

Whats a sock crank? Must be a stock crank.

What bearings are you going to run?
What weight oil?

For the ring gaps. What factor did you use to figure your ring gaps?
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Old 01-16-2013, 06:38 PM   #3
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Originally Posted by BogusSVO View Post
You do know you will be more than 11.5:1 cr with that set up... and a turbo?

Hope you are running E85

Whats a sock crank? Must be a stock crank.

What bearings are you going to run?
What weight oil?

For the ring gaps. What factor did you use to figure your ring gaps?

Ok so no I will not be running E85 it is too hard to get where I live. I know the compression ratio will be higher than that just means tune has to be dead on and I will be running water/meth injection to help with that.

I am running a stock crank witch are proven to hold up to the power I want

And as far as bearings go I am torn between acl race bearing and honda factory bearigns. I am pretty sure I am going with factory bearing mostly because they are available in many half sizes to get the bearing gap just right

As far as oil I have no idea I was thinking 5w-30 or 10w-30 synthetic is what I would like to run.

The ring gap I came up with off of wiseco's wesite for their pistons and came up with

top-0.015
second - 0.017

I opened those up a little because according to most information with their website they assume low compression pistons are turbo and high compression are n/a so with the compression I would rather is a little loose than tight
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Old 01-16-2013, 06:57 PM   #4
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Ok.. so you do know the life span of this engine is going to depend on the tune.

Run the factory Honda bearings, IMO,

What kid of rod side clearance are you going to run?

10/30 should be fine, just do not think it will go 3k miles. But here have a good mech oil gauge hooked up and check your oil pressures, at a few set points, you may have to change weights.


How much boost?
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Old 01-16-2013, 07:34 PM   #5
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I am suprised the factory rod and main gaps are that loose.

Robello recommended that I go .0020-.0022 on the main and .0018-.0020 on the rods on my BP motor. I would consult with a Honda specialist on your motor. If you go loose, you should run a heavier oil, especially if you are tracking.

11.5:1 Compression? That is high, but your larger camshaft should bleed off some of the compression. Not so sure I would run that on pump gas. Maybe you can get away with it, but I would start out on race fuel or blend of race fuel and pump fuel until you know you have the tune right. Once I was comfortable with the tune, then I would tone it down for pump gas.
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Old 01-16-2013, 08:17 PM   #6
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Quote:
Originally Posted by BogusSVO View Post
Ok.. so you do know the life span of this engine is going to depend on the tune.

Run the factory Honda bearings, IMO,

What kid of rod side clearance are you going to run?

10/30 should be fine, just do not think it will go 3k miles. But here have a good mech oil gauge hooked up and check your oil pressures, at a few set points, you may have to change weights.


How much boost?

Yes the tune will be a huge deciding factor in how long this engine survives and I know that and am willing to take that risk as far as the rod clearances this is why I started this thread I am not sure what to run and it be safe and stay together. I have a mechanical oil pressure gauge and I always watch it like a hawk. Also remember this engine will never see more than 7200 rpm max I am not gonna rev it to 9 like every other honda idiot and expect it to stay together.
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Old 01-16-2013, 08:21 PM   #7
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Quote:
Originally Posted by miata2fast View Post
I am suprised the factory rod and main gaps are that loose.

Robello recommended that I go .0020-.0022 on the main and .0018-.0020 on the rods on my BP motor. I would consult with a Honda specialist on your motor. If you go loose, you should run a heavier oil, especially if you are tracking.

11.5:1 Compression? That is high, but your larger camshaft should bleed off some of the compression. Not so sure I would run that on pump gas. Maybe you can get away with it, but I would start out on race fuel or blend of race fuel and pump fuel until you know you have the tune right. Once I was comfortable with the tune, then I would tone it down for pump gas.
I am posting a picture of the stock main and rod clearances below. I do not want to go too loose and have to run 50w oil just to keep the saftey of the motor I would much rather 10w 30 and be done. The compression is a little high but I really want the benifits of both all motor and turbo setup. My cams will be designed to bleed off a decent amount of that compression so the effective compression will be lower. I do not have the exact cam specs at the moment I am working with Delta to design an appropriate cam for my setup.
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Old 01-16-2013, 08:29 PM   #8
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Here are the stock recomended rod and main clearances




I do not know what rod and main clearances to run because I have never built an engine meant to take this much abuse this is why I need help.
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Old 01-17-2013, 11:47 AM   #9
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Quote:
Originally Posted by Sean View Post
I do not know what rod and main clearances to run because I have never built an engine meant to take this much abuse this is why I need help.
Your questions seem to go beyond the limit of "general advice/info" into more of the "very Honda specific" variety. Why not ask on honda-tech or similar forums, they used to have some very knowledgeable members 5-6 years ago if you find the right sub-forum.

There's bound to be people with experience doing what you're proposing that could share their outcome.
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Old 01-17-2013, 02:44 PM   #10
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+1. I have no idea this thread hasn't been moved to BS yet - it has absolutely nothing to do with Miatas.
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Old 01-17-2013, 11:46 PM   #11
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Quote:
Originally Posted by SJP0tato View Post
Your questions seem to go beyond the limit of "general advice/info" into more of the "very Honda specific" variety. Why not ask on honda-tech or similar forums, they used to have some very knowledgeable members 5-6 years ago if you find the right sub-forum.

There's bound to be people with experience doing what you're proposing that could share their outcome.

I will go and put it on honda - tech now but it seems with everything I ever posted there I never get even a remotly good response I was hoping some engine builders on here could help me.
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Old 01-17-2013, 11:48 PM   #12
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I did not post this on Honda-Tech because I was hoping for some good engine builders responses not the normal B.S. you get over there. I posted in in the miata forum because I thought it was relevant to buildind any high HP 4 cyl. engine I guess I was wrong I will go post it over there.

Mods please move this to the B.S.> thread.
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Old 01-18-2013, 12:31 AM   #13
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Quote:
Originally Posted by Sean View Post
I did not post this on Honda-Tech because I was hoping for some good engine builders responses not the normal B.S. you get over there. I posted in in the miata forum because I thought it was relevant to buildind any high HP 4 cyl. engine I guess I was wrong I will go post it over there.

Mods please move this to the B.S.> thread.
Its really not, no offense.
Our engines have next to nothing in common with what you're building.
There is no "general" engine building knowledge, per se.
You build to fix the weak links and improve on the strengths - all of which vary wildly between different engines.
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Old 01-18-2013, 12:52 AM   #14
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How much boost do you estimate you will need to achieve your goal? With that much compression I would think that thermal expansion would be considerable. I went with .30 for the top and .34 on the second rings on my build so I went about .008 wider than the minimum for JE's nitrous calculations. I feel this was a good compromise but we'll see after break in and then compression testing.
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Old 01-18-2013, 02:18 AM   #15
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Originally Posted by 18psi View Post
Its really not, no offense.
Our engines have next to nothing in common with what you're building.
There is no "general" engine building knowledge, per se.
You build to fix the weak links and improve on the strengths - all of which vary wildly between different engines.


No offense takin I just really hate honda tech out of all the forums this one is one of the few you can get real answers from someone without 100 BS responses first but I can understand the engine specific part of things. I just want to build it right the first time.
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Old 01-18-2013, 02:24 AM   #16
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How much boost do you estimate you will need to achieve your goal? With that much compression I would think that thermal expansion would be considerable. I went with .30 for the top and .34 on the second rings on my build so I went about .008 wider than the minimum for JE's nitrous calculations. I feel this was a good compromise but we'll see after break in and then compression testing.


I do not want to run more than 15 psi at the absolute max I would hope for more around 12-13psi. Daily I will run about 8 and turn it up when I want to. I am fearful of thermals inside the compustion chamber and I am seeing similar builds with piston to wall clearances at as high as .006 so I need to look into that as well.
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Old 01-18-2013, 03:06 AM   #17
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It is now on honda-tech lets see what kind of crazy replies I get now
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Old 01-18-2013, 08:37 AM   #18
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It is now on honda-tech lets see what kind of crazy replies I get now
Link so we can laugh at the responses.
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Old 01-18-2013, 03:19 PM   #19
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Need Help Building a 350-400hp engine!!!! Clearances, ring gap Turbo high comp. LSV - Honda-Tech


Already getting responses of what I should do to make my "setup" better nothing to do with what I actually asked this is why I hate honda tech
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Old 01-20-2013, 03:56 PM   #20
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I have built some honda, i have used honda factory specs, but i may run the rods and mains a tad looser for race motor. If your using aftermarket rings/pistons, they will tell you gap specs. And you can use the old saying .001 per inch of journal diameter for clearance
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