Building a high cr n/a engine. Need opinions
 

I know this is a turbo forum but I have come across some n/a builds.
I am about to build my 95 1.8L, it will be used for autocross and track days. Will use regular gas
I have some questions (look next to "my plans")
My plans are the following:
-MS3 for ecu
-bp 1.8L bottom end.
-99-2000 head with some minor porting, gasket match bla bla.
-Racing beat header (do I need a 99-2000 header or do I use the 94-97? I know the intake ports are different, what about the exhaust ports?)
-99-2005 square top intake mani
-SCAT rods
-stock or 11.1cr supertech pistons. Most likely stock (now here is my question. Emilio's car has a 2001 bottom end and he is using a 99 head shaved .015", I read that the 99 head has a larger combustion chamber than a 94-97 head and milling it a bit is needed to achieve same cr as a 94-97. If I use the 11.1cr supertech pistons should I mill it to keep the 11.1cr? or should I leave it alone. If I use the stock 9.5cr pistons how much can I safely mill the head to raise compression without starting to knock on regular gas or hitting valves? -maybe .020-.030"? has anyone done this?)
-Mazdaspeed intake camshaft
-will need adjustable cam gears if I mill the head. Are the OBX ones decent?
-Injectors. Will stock freshly cleaned injectors suffice?
-coolant reroute.
-ACL bearings, studs.
-Boundary engineering oil pump gears, does anyone else make them? (I wonder how high I could rev this engine with the mods I plan and still make power) Maybe I can go with stock oil pump?
-Oil cooler, probably home made.
-1.6 act HD organic clutch, cusco 10lb flywheel.

Ok those are my plans/questions. I tried to search for all the answers and those are the one I couldnt find. Thanks

Any ideas, opinions will be appreciated

Why not start with a VVT engine instead?

Sure, there are much less options for cams (no intake blanks available at the moment) but you start at a slightly higher CR and have the potential to spread the torque curve a bit.

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.

Easier solution: Buy a k20(comes stock with more power than you could get out of any Built BP on 93) and just focus on the fab work. Win.

I think if you buy the pistons for 99-up and they will likely compensate for the head differences.

You want to run 11:1 on pump gas? I don't think you will get as much timing advance without detonation on 92-93 octane as you might need for peak torque.

You asked about revving high but didn't include an ATI damper. I would, especially with a lightweight flywheel.

Boundary is the only reasonable place for the good OP gears.

You forgot shim-under-bucket lifters. If you are planning to rev high you will want them to reduce valvetrain weight.

You will want adjustable cam gears even if you don't mill the head, just to dial in power on the dyno.

I'm not a big fan of milling heads unless they are out of true. They can be more prone to warpage as the metal sealing surface thins out. And if you bother to do porting, you may need the head not to be out of chances to mill for true in the future. You don't want to have to buy a new head the first time you have a problem. Same with the block.

Also invest in a 53mm radiator if you haven't already.

Sound logic if you will spend the most of the time free revving.
From the crank perspective the clutch will hold it firmly to the drive-train and the crank pulley will be the loose end (and the rods puts their momentum on it in between these points). The weight of the flywheel is only noticeable in the cases where it's weight is a noticeable inertia of everything connected to it (i.e. clutch engaged or very low gear).
So I would say that the weight of the flywheel have very little to do with the dampening of the torsional vibrations in the crank (which get worst at the front, oil pump)

But ATI damper and improved Oil gears are on my list (but not ordered)...

As soon as you pop any engine open, the drainage of cash starts (so will a K20 if it's not perfect from the start).
I'd be surprised if the whole gasket/sealing/sealant-kit for a BP goes for under $1k (at least it feels that way, especially if you add 5-6 shipments since you always forget some small thingy).

You dont need to open a k20..... With a RBC intake mani, header, and cam with engine managment you can put down 250+ whp :jerkit:

Completely stock with a decent intake and catless exhaust will put down 200+ whp

...and 140wtq. Still, I'd probably rather have the S2k engine in my car thatn what I have now. Then again...no, I wouldn't.

So you will never need to open a K20...
I know Honda are building their engines well, but never needing a overhaul... ;)

With the fabbing needed, who would not spend some time verifying the engine is sound, going beyond a leakdown. And while you're at it...

Fiddling with engines is never inexpensive, regardless which path you choose. And of course it's easier to choose a LSx if you want 400whp N/A. But you can always play with the BP a little until you want to man up and hunt for interesting gearbox options etc.

K20 is not a bad engine in any way, but it's not a baby step from a BP as a slightly modded BP is. The OP is worried about keeping the header...

more like 160 wtq....either way pretty sad you can pull just as much power out of a bolt on 2 liter than you can with a moderatly boosted BP. :drool:

:bowrofl::bowrofl::bowrofl:

the noob is right though, (and its f20c not k20 btw), the honduhh engine bone stock will make much more power than a race prepped n/a BP.
It is a very involving and quite expensive swap though, so definitely not for everyone.

And no, it will not beat or keep up with a moderately boosted bp, unless your definition of moderate is 5psi. I fart more than 5psi

No one pointed him to the hipster forum yet? They love high comp high revving low power ITB'ed motors

well since he mentioned auto-x and track days and not hardparking and fellatios we're thinking he might not fit in there

Yeah, I'm really jealous of any 4-door Honda sedan driving down the highway, driven by a mom, lol.

either way, why run pump gas and not e85, it may not make as much sense for a N/A vs boosted motor but higher octane and less knock/dett may help? If the op can even get access to anyway. plus its cheaper than even 87

because its nowhere near as beneficial on n/a application (even with high cr) and will not make any more power or be significantly safer.
And yes it will be much more expensive because the car will still consume roughly 30% more of it vs pump gas.
On a high cr n/a application race gas is king.

anyway from what I have read, and if I had the extra 700 bucks lying around why not shoot for carillo rods, they are lighter and will help the motor rev smoother. If he plans to use the 99-00 head why not try the exhintake cam swap instead of the mazdaspeed cam? unless that only works for the 94-97 head as thats all ive seen it used on

so someone's made one rwd, cool.
even more work than an f20c

I should have added in my first post that I am trying to build this engine on a relativelly low budget. I though about going VVT but that involves more $. Im ok with the SCAT rods because they are $250 instead of $750. Thats $500, I can almost get a MS with that difference.
And I know I said high CR but if I keep the stock pistons and I add the rods I could always turbo or supercharge in the future.
About the exhaust-intake swap. Do I just use an exhaust cam on the intake side too?

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?

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.

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.

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?

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.

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?

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.

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

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.

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.

Secret turbo?