Engine build halt! CA18 GURUS nEEDED !!!

[sldwys]

hey all. My engine builder needs some information.
I have a Tomei 2L Stroker Crank
Stock Sized Greddy Rods.
HKS 85MM Pistons.

Now.... I have been asked to fine the difference between the stroke from stock to tomei crank, and the Man bearing clearances for the tomei crank.

Stock crank stroke = 83.6mm bore
Tomei Crank Stroke = 88.0mm
Difference of 4.4mm.

Anyone know where I can find the main bearing clearance specs for a tomei 2L crank ?

I also need to find the Height of the pistons tomei uses for their 2L kit, and the height of the HKS 85mm pistons.

Last but not least I have been asked to find the Piston to bore clearance sheet for the HKS pistons ( which i never got in he box when they arrived to me )
Please help me out in order to see my amazing little ca buld get near completion.

thanks!

[float_6969]

Oil clearances shouldn't be any different than stock, refer to the FSM.

You're not going to be able to run the setup that you have. The piston will come up out of the bore 2.2mm. Tomei made a piston to go with that crank that you need to use. They shortened the overall piston height and moved the pin up. You can't put a stroker crank in an not change AT LEAST the piston. Sometimes you have to change the rod and piston to get it to stay in the bore. You're also going to have an issue at BDC because I'll bet your piston hits the oil squirters and breaks them off because it's going to come out of the bottom of the bore another 2.2mm as well.

The piston to bore clearance SHOULD have been included in the spec sheet that came with the pistons. If not, you're SOL there. Trying to contact HKS for information like that is next to impossible. I tried to contact them about specs for my cams and got no where.

[boost_boy]

Whatever float says It seems to be easier to start with a CA20 block and build from there. Too much trickery involved with making the CA18 block a legitimate stroker block. Do you have pictures of this crank? I would love to see it in depth if at all possible.

[sldwys]

ok so i have a few other questions.
The HKS Pistons I have.... there is no information anywhere about them. But I have read somwhere in my hours of internet trawling that HKS Made a Competing piston to be used with the Tomei stroker crank. I have no information on my pistons other that they are " HKS Special Piston Kit 85mm Ca18" Thats what they say on the box. So ...... If i were to get these measured by my machinist/assembler what would I expect to see/measure if they were in fact the hks pistons to use in the tomei stroker kit ?
If I cant use these pistons, This crank, these Rods in my ca18det block - Would in fact this setup work in the ca20 block ?
If I have to use the ca20 block, Is all that is required is drill + tap for tensioner, Enlarge and TAP cylinder head bolt holes, And drill and tap oil squirters ?
Sorry for all the questions - Im trying to get this engine sorted asap.
Thanks.

[boost_boy]

If I wanted a CA20DET or CA20DE, I would start with the CA20 and work from there. I'm very sure the Tomei crank would fit the CA20 block, but you're going to have to pioneer it because no one around has attempted it. I do believe it all will work if you want it to as you are determined to have a CA20DET. Just remember, you're going to have to play with the timing belt, drill and tap for the timing belt idler pulley and some drilling and tapping on the block's deck for the head bolts. Maybe I should try this to eliminate all the concerns of having a true CA20 as opposed to playing with your stroker (Get it) playing with your stroker .

[sldwys]

well I might be in luck. The HKS 85mm pistons were make for a stroker kit, But alas I cant find any other info to find out what was changed with them. eg jut the bore size, Or the length of the piston. If I cant get those pistons to work, Ill sell them off, and get some CP's with a shorter piston, And the wrist pin 2mm higher.

[float_6969]

It won't be hard to assemble the motor without the rings and oil squirters and spin the crank and see what happens. Otherwise you need to take a lot of measurements and do all the math to see if it will work.

[tommey]

You have to measure the compression height of the pistons.
Then you will find out if you can use them without changing the rods.
If they won`t work i would order a custom set of pistons, cheaper and faster than custom rods.

[sldwys]

thats what im thinking tommey, If somthing doesnt work get the pistons changed. Eg CP have a 4-6 week turn around. And I dont think ill ever find gredddy rods for a ca18 again
I shall ring my engine builder today.

[tommey]

You can get them in 1 week, if you pay more.
I think it`s something like 20% more.

[sldwys]

hehe its taken 7 year to get to here, another 4-6 weeks is fine with me.
So anyway - My HKS pistons... came with no spec sheet as stated. After all the searching I have done, I have not found any clearance info or for a fact.. no info at all for a 85mm ca18det HKS special piston kit. But... According to every other engine HKS tend to have a .045 ~ .055 clearance ( 2 thou ) Does this seem about right to anyone else ?

cheers

[tommey]

If they are made of a similar alloy as the Tomei pistons that clearance seems to be correct.

[sldwys]

brilliant, thanks. An im guessing as the same as tomei Measurement of the piston should be taken from the skirt, about 10mm above the bottom of the piston itself ?

[tommey]

Like on almost all other pistons, yes.
Unless you find any specific info on ring gap, maybe you should play it safe there.

[float_6969]

The piston to cylinder wall clearance you posted sounds right. It's unlikely that HKS used different aluminum alloys for different engines, so you'll probably be OK with that range.

tommey is right about where to measure the piston diameter at, but that's common knowledge, and your builder will know that. The ring gap something you'll want to find info on/talk to the builder about. Do you happen to know what material and design the ring set is made of?

[sldwys]

This is my engine builder here, He has won the record for fastest 2L N/A on the salt flats!
http://www.youtube.com/watch?v=CC0hoW3zpso

Anwyay I have no idea what the rings are made of at all, as I said theres no documentation with the pistons.
Also ontop of the piston issue ( which can be sorted im sure ) my engine builder has asked if the cams are solid or hydraulic lifter, Now.... To my understanding it doesnt matter what they were for if you were converting to solid lifter ? Maybe I was wrong. The Valves I have ( super tech valves ) are too long for my cams lift and theres no room for the shim bucket to be installed. Can this be accomplished still by machining the valves shorter ? or is it worth me selling the stock sized valves and buying oversized/shortened valves if they are readily available ?

thanks.

[sldwys]

also - Do my pistons seem to be shorter than stock ? from the top of the piston to the center of the wrist pin is 29.4 mm . Or am I going to need to sell these and get custom pistons ?

[tommey]

Stock compression height is about 30mm.
If you are planning to use solid lifters then you can use camshaft with either hydraulic or mechanical lift profile.
There are ofcourse benefits of using a mechanical "lifting ramp"/profile.

You can shorten down the valves, but there is a limit.
If you have to move the locks further down then your spring seats would need to be machined.
You dont need any oversized valves unless you are aiming really high.

[sldwys]

well my cams are out of this world big. 312 deg with a 10.25mm lift, Hydraulic lifters, supertech valves, and dual valvespring kit, with titanium retainers, So Ideally I want the stock sized valves... just with a shorted stem.

ang bugger. looks like ill have to sell my pistons and buy some custom CP's.

[tommey]

There are plenty of firms making custom valves.
Wow, maybe you should just drop the turbo

[sldwys]

haha yeah ... nah! lol once you go turbo you never go back. I have a NA thats fun to drive lol.

so I rung the engine builder, He said that the problem lies with the shim on top of the valve, and he said that there is not enough room on top of the valve stem for the shim to locate onto.
what has everyone else done in regards to going solid lifters ?

I have The following.

312 deg cams
Tomei Solid lifter kit
Tomei Test shim kit
Supertech Dual valve kit
Supertech intake and exhaust valves.

From what i can gather they are saying the distance between the top of the valve stem and the start of the collet or... lock? recess is 3.25mm. And they are saying that is too small, and should be more like 5mm. Is this right ?

[tommey]

if you can run without shims, do that!

[float_6969]

I'm no help as I haven't messed with solid lifters on this engine.

[boost_boy]

With Tomei camshafts, this would be much simpler. Tomei, like JUN, has a recommended clearance for the base circle of the camshaft lobe and lifter bucket. You would have to do this process for each individual lobe/lifter, so it it time consuming. To achieve the recommended base circle, one has to adjust (grind) the shim to a size that brings a particular bucket and base circle clearance on the camshaft lobe to the specified clearance. This is a very tedious process and a machine shop would charge a hefty price for such a task. I personally would charge upwards of $500 just for the adjustments alone, so it gives you some idea. I did my own with the help of one of our Aussie members, that pointed me in the right direction. My machinist didn't do anything at all, so when I did a leak-down test before adjustments were made, the engine leaked air like crazy. As for your camshafts, I figure the clearances would be nearly identical @ 1mm clearance.

[sldwys]

the guys with my engine, are very well known for their high hp sr20det gtir pulsars. so itb and also solid lifters standard. Thus making them assume the shims are meant to slot on top of the valve stems. where as when you are converting to the tomei solid buckets, the shims go upside down on the bucket. this is what they were referring to about the top of the stems being too short. Im guessing they haven't done too many ca18's.
Anyone want to buy some 85mm HKs pistons ? LOL.

also - I need to know the measurements in order to get the custom pistons made..... Do I just get say 84mm bore, with the height of the piston reduced by 2mm, the Wrist pin centre lifted 2mm, and what about the relief for the oil squirters ?

cheers

[tommey]

What you should do is ask the ones ordering you pistons to take the CA18 design that CP has on file and make the required changes.
By moving the pin up you will need to move the ring groves also.
Bad photo, but you can see that on my pistons with the bigger pin its starting to get close to the oil control ring.

[sldwys]

Can someone please tell me!!

are these the correct pistons I need ?

http://www.ebay.com.au/itm/CP-Pistons-N ... 3cd9267d55

tomei Stroker crank - Stock spec forged rods

[Izento]

Geez, you've been at this stroker kit for a long time, lol. I know you are most likely looking to piece together this kit, but you can also get a stroker kit from Norris Designs. It's quite expensive but if you sell all your stroker parts, I think it wouldn't be too expensive for you. Just something to think about.

http://www.norrisdesigns.com/proddetail ... S13-014004

[float_6969]

Do you have the engine at a machine shop? They should easily be able to figure out what The change in compression height needs to be on the piston to accommodate the change in stroke and get the piston ordered.