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Building a high cr n/a engine. Need opinions

Old 01-24-2012, 03:51 AM
  #21  
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and how hard is it to run e85? just a gas line flush? How much compression can be achieved with e85 and how much to mill a 99 head before smashing valves on a bp block?
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Old 01-24-2012, 09:29 AM
  #22  
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It's easy but in a N/A application it's basically never used because e85 has like 70% the efficiency of gas, it's just more stable, hince the higher octane. Basically, you would get absolutle horrible gas milage(5-20(max)) for 5 whp gain. However in boosted applications you can really up the boost and advance timing which result in much larger gains depending on turbo, boost and engine size.

Think of it in comparison to a one speed bike changing the crank gear versus a 7 speed bike changing the crank gear in relation to top speed. Yes, the once speed could benefit from the change in crank gear but the 7 speed would be exponentially better.
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Old 01-24-2012, 09:39 AM
  #23  
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Originally Posted by btabor View Post
About the exhaust-intake swap. Do I just use an exhaust cam on the intake side too?
Exhaust cam, cop off the CAS drive, drill new hole for cam gear (unless you have adjustable).
Or buy an MSM intake cam and just install.

Re: E85 in N/A application. Apparently you have to be very careful with tune when you reach for the edge (14:1 CR etc which you need to take any advantage of it), "knock is supposed to sound" different (or just much harder to detect).
Or the people I've met who have melted piston after piston just had a -----poor control of their tune.
E85 is for Turbos.
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Old 01-24-2012, 11:11 AM
  #24  
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Originally Posted by NiklasFalk View Post
Why not start with a VVT engine instead?

<snip>

I have ST 84mm 11:1 pistons going into my build and will see what the final CR will be after decking (pistons flush with block, stretch in the 0.8mm gasket) etc. My comb cambers became 52cc after some unshrouding.

The exhaust ports are the same for all BPs, so you can use your old header.
Looks like we are building twins!

My 94 block is decked .020" to get the squish under .040" with a .030 head gasket. With that amount removed my ST 84mm 11:1 pistons are .005 below the deck. My chamber volume is also 52cc's (head was not shaved). After measuring everything, I calculate my CR to be 9.9:1, much lower that the advertised 11:1.

Also with the .020" revolved from the block, it looks like there is about .008" interference (with oem gasket) between the piston and the exhaust valve at TDC with the valve fully open, but hopefully I will never see this condition during operation!

94 block
'01 VVT head, mild porting
ST 84mm 11:1 pistons
Flat top IM
Toyota COP
DIYPnP & VVTuner
RB 4:1 header
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Old 01-25-2012, 01:47 AM
  #25  
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Originally Posted by GraemeD View Post
Looks like we are building twins!

My 94 block is decked .020" to get the squish under .040" with a .030 head gasket. With that amount removed my ST 84mm 11:1 pistons are .005 below the deck. My chamber volume is also 52cc's (head was not shaved). After measuring everything, I calculate my CR to be 9.9:1, much lower that the advertised 11:1.

Also with the .020" revolved from the block, it looks like there is about .008" interference (with oem gasket) between the piston and the exhaust valve at TDC with the valve fully open, but hopefully I will never see this condition during operation!

94 block
'01 VVT head, mild porting
ST 84mm 11:1 pistons
Flat top IM
Toyota COP
DIYPnP & VVTuner
RB 4:1 header

sounds good, how much power are you putting down? And why exactly is the "squish" why did you deck the block so much if you ended up using a thicker gasket?
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Old 01-25-2012, 01:51 AM
  #26  
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Im starting to think I should go with the stock pistons and not shave the 99 head. Then compression will end up around 9:1 and I can always boost later.
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Old 01-26-2012, 09:42 AM
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sounds good, how much power are you putting down? And why exactly is the "squish" why did you deck the block so much if you ended up using a thicker gasket?
None at this moment, it is not done yet. Just finished grinding on the valve cover for the COP's and waiting on a valve shim. But we will see how much power it makes. I just want a reliable track car that, if it finds a wall, I won't be to hart broken.

Squish or quench, helps prevent detonation and improves combustion. A quick Internet search will have you reading for hours. I am using an stock head gasket and it measures .031 thick. So compressed it should be .030" ymmv.
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Old 01-27-2012, 02:01 AM
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Originally Posted by GraemeD View Post
None at this moment, it is not done yet. Just finished grinding on the valve cover for the COP's and waiting on a valve shim. But we will see how much power it makes. I just want a reliable track car that, if it finds a wall, I won't be to hart broken.

Squish or quench, helps prevent detonation and improves combustion. A quick Internet search will have you reading for hours. I am using an stock head gasket and it measures .031 thick. So compressed it should be .030" ymmv.
Sounds good. I wonder how much I can mill the block or head using the stock pistons and a 99 head and be safe. Same questions goes if I use the ST 11:1 pistons.
Is it better to mill the block than the head to prevent head warping?
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Old 01-27-2012, 10:17 AM
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If you mill just the head, you won't change the squish, only the compression ratio. If you mill the block the CR and the squish change. But you must make sure that your pistons are below the deck before. Milling the block will not work if your pistons are already flush with the deck. The ST pistons have a smaller compression height than the stockers that came out of my block. I don't know why, maybe some 1.8s have different stock piston compression height, and they make one that works in all of them.
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Old 01-27-2012, 02:48 PM
  #30  
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A question about decking and shaving;
How much can be taken off the complete height before the cam belt stretcher needs to be modified (i.e. the belt become too long)?
Making the stretcher/follower bigger could be one mod,if needed and there is room.
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Old 01-27-2012, 03:21 PM
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Originally Posted by NiklasFalk View Post
A question about decking and shaving;
How much can be taken off the complete height before the cam belt stretcher needs to be modified (i.e. the belt become too long)?
Making the stretcher/follower bigger could be one mod,if needed and there is room.
An adjustable cam gear on the exhaust side will restore the proper timing
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Old 01-27-2012, 04:04 PM
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Originally Posted by GraemeD View Post
An adjustable cam gear on the exhaust side will restore the proper timing
So that's the way you fix the tension in the belt...




I just try to figure out if there is a risk I need to fix a tensioner problem too since i will have my ST 11:1 flush with the block, or I will not reach mu CR and Squish goals.
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Old 01-28-2012, 11:00 AM
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Originally Posted by NiklasFalk View Post
So that's the way you fix the tension in the belt...




I just try to figure out if there is a risk I need to fix a tensioner problem too since i will have my ST 11:1 flush with the block, or I will not reach mu CR and Squish goals.
There is plenty of adjustment for the tension roller, you would have mill a bunch of material off in order to run out of tension.
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Old 02-09-2012, 03:49 PM
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Got a call from my builder.
The ST 11:1 pistons are 0.75mm (almost 0.030") down into the block, and the resessed "squish edge" is another 0.15mm down.
Such a lowered edge have he only seen as a solution to blowing head gaskets for high boost enginges, but never used on N/A, maybe ST use the same processes for all pistons regardless of use?
So the block will be decked 0.75mm to make the pistons flush, it should work but we are aware that the valve pocket will be off center of the valve and there is a risk of hitting the edge.
The head is in another shop for pressure testing after a third session of welding/gridning (I really hope that it won't leak now) so we can't verify the margins (using no headgasket).

Oh, well. The next time the engine will be redesigned it will be fully custom pistons. But I hope it will run a season or two with this.
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Old 02-09-2012, 05:25 PM
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Originally Posted by Boost Joose View Post
Secret turbo?
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