Opinions - B18CR Bottom End with Alaniz head

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Originally Posted by jdmTYPE R

a lil modification on the ctr piston will get it to work fine...

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So why are you going to a B20 then?

im staying with 1.8 with forged internal

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Originally Posted by TODA AU

I’ve gotta say I’m with Benny on this one…
If you use B16C CTR pistons,
Without machining the block, you’re already approaching a zero deck
(0.006” to move on a virgin block)
The pin height of the B16B piston is 30.73mm
The B18CR piston pin height is 30.23mm
With only 0.005” machined off the head & block combined,
You’ll have a compression ratio of 12.9:1
This can be troublesome with 98RON fuel & short duration cams.
(With comp this high, you’re better off with E85 or race fuel)
If 0.010” of material is removed, you’ll have to look a 0.8mm or even 1.0mm head gaskets to maintain acceptable piston to head clearance.
As a side note, I don’t like the crowns on CTR pistons either.

If you’re on a budget & want respectable gains from the head & cam swap
& the bottom end is actually in good condition & fine to re-use…
Pull it down, tickle it a bit here & there & strap it back together.
It’ll only cost you a bit of time, some machining & a set of gaskets
(You're swapping the head anyway so it's not much extra work IMO)
.
Keep your original B18C7 pistons…
& machine no more than 0.020” off the top of the block…
This will give you a comp of 12.1:1 (assuming the chambers aren’t bigger & the head isn’t shaved)
To get it right, you will have to do a bit of measuring & a few sums,
But, you can have 12.0:1 C/R with little spent
IMO this will work better on 98RON pump fuel than moving the CTR pistons.
& you’ve maintain acceptable piston to head clearance with original head gasket.
Once it’s ready to go back together, you’ll need to get the cam timing right or your piston to valve clearance will become an issue.

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Thanks for that -- when you say a tickle, you mean rebore,hone etc new rings yada yada -- I don't want to pull the block out at the moment, much bigger job for one person that replacing a head.. Can I do anything worthwhile with the block still in the car? (Guessing I can drop the bottom end out and replace bearings etc too.. ) given the engine now has 120,000kms you may be right ... this is getting expensive quickly lol ..

The heads comubstion chamber volume increased from like 39cc to 43.5cc

that sounds strange?

Alaniz takes a b16 head and then ports it -- This is the competition port, good for strong mid range and top end gains, the top level port is really for drag only...

So I am assuming during the reshaping of the combustion chamber and valve seat etc a little extra volume was found. With a stock Head Gasket he says will retain stock levels of compression -- I gotta believe him, he's got huge credit for a lot of cars in the states including Eriks Racing etc ...

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Originally Posted by ewendc2r

Thanks for that -- when you say a tickle, you mean rebore,hone etc new rings yada yada -- I don't want to pull the block out at the moment, much bigger job for one person that replacing a head.. Can I do anything worthwhile with the block still in the car? (Guessing I can drop the bottom end out and replace bearings etc too.. ) given the engine now has 120,000kms you may be right ... this is getting expensive quickly lol ..

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Re tickle...
No, not at all...
Yes you'l have to pull it down, & yes there is little machining required...
But total cost is only approx $100 + a few gaskets & seals.
Leave the bores, rings, crank & bearings alone if you were happy to before...
But - measure deck height...
Measure the piston to deck height...
& machine deck surface to acheive desired compression ratio.
Clean it up, use wet & dry (800) & your thumb for the edge at the top of the bore & put the pistons back in with an 81.00mm sleave...
Stay away from ring compressors & you'll shit it in.

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Originally Posted by ewendc2r

The heads comubstion chamber volume increased from like 39cc to 43.5cc

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So they're a little larger so the comp will be down just a touch...
Std is 42.7, you're up 0.8cc.
So we can asume you have deshrouded & CC'd chambers
You'll still be able to get 11.8:1 which is still nice on 98 :thumbsup:

the thing that was strange was the 39cc...

even a VTiR head (smallest OEM cc) is 41.7

ahh that sounds right -- don't have access to the email he sent me, i must've plucked that smaller reading from somewhere else lol (he said a B16 head, would that account for reduced cc volume of 39 or whatever i said?).. Yeah its a competition port with signficant work on the valve seats and combustion chamber. 11.8:1 is ok I guess, especially for the meanwhile (and as you said, I was happy with less before).

But the work you are talking about still requires me to pull the block out of the car which means its unlikely to be useable for at least 1 wk (and be a pain in the ass to get it to a workshop & expensive if I get them to do it all).. Is there any method for machining the block while in the car? What about honing?

What RPM is the Oil Pump gear good to? I think you said around 9200rpm Adrian? Bottom end should be good in stock form for around 9100rpm I figure from reading, with 9300rpm being the critical point and reliability comes into play.

If I didn't want to do any machining and assuming the block doesn't need it (block surface) could I drop the bottom end and rebuild with block in the car new rods / pistons that increase the CR maintaining stock deck height? Then I can effectively have a new engine as the crank should be in good nick.. With forged internals I 'should' be able to carry a much higher redline reliably yeah? I mean, it would likely support Toda C2 and M24X cams to around 9500rpm or so?

And lastly -- I understand with sleeving you should get them installed and then machine the deck. And I also understand this is a must as high rpm can crack cylinder wall, but what rpm is considered risky? ie Trying to figure out if this is necessary in any case if I am increasing rev limit over 9000rpm. Then I have little choice but to do the rebuild anyhow.

maybe he adds some strategic material,measures then deshrouds/whatever :confused:

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Originally Posted by ewendc2r

ahh that sounds right -- don't have access to the email he sent me, i must've plucked that smaller reading from somewhere else lol (he said a B16 head, would that account for reduced cc volume of 39 or whatever i said?).. Yeah its a competition port with signficant work on the valve seats and combustion chamber. 11.8:1 is ok I guess, especially for the meanwhile (and as you said, I was happy with less before).

But the work you are talking about still requires me to pull the block out of the car which means its unlikely to be useable for at least 1 wk (and be a pain in the ass to get it to a workshop & expensive if I get them to do it all).. Is there any method for machining the block while in the car? What about honing?

What RPM is the Oil Pump gear good to? I think you said around 9200rpm Adrian? Bottom end should be good in stock form for around 9100rpm I figure from reading, with 9300rpm being the critical point and reliability comes into play.

If I didn't want to do any machining and assuming the block doesn't need it (block surface) could I drop the bottom end and rebuild with block in the car new rods / pistons that increase the CR maintaining stock deck height? Then I can effectively have a new engine as the crank should be in good nick.. With forged internals I 'should' be able to carry a much higher redline reliably yeah? I mean, it would likely support Toda C2 and M24X cams to around 9500rpm or so?

And lastly -- I understand with sleeving you should get them installed and then machine the deck. And I also understand this is a must as high rpm can crack cylinder wall, but what rpm is considered risky? ie Trying to figure out if this is necessary in any case if I am increasing rev limit over 9000rpm. Then I have little choice but to do the rebuild anyhow.

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What are the intented use of the motor? What are your power goals?

As per clubitr thread - Air flow > compression.

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Originally Posted by fatboyz39

What are the intented use of the motor? What are your power goals?

As per clubitr thread - Air flow > compression.

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I guess with the head and cam combination on the stock bottom end I would be dissapointed with less than 140kw@wheel peak and strong midrange.. Maybe 135kw would be a 'ok' improvement until bottom end is built. After that I guess 150kw is well on the cards but through all the parts not just the engine working hard etc -- Better flow, more efficient etc removal of parasitic losses etc.