I'm going to have a Darton MID liner kit fitted into my B18 Type R bottom end. I currently have a 27lb 87.2mm stroke eagle crankshaft and B18C Corrillo forged rods. I was hoping that I could buy some CP 84-85mm pistons in 12.5:1 compression. On there website it says that compression is only with 89mm stroke. Does that mean I have to spend more money on new crank and rods (not to mention bearing shells) to get that compression? Is there another way of getting high compression with the 2 litre darton sleeve kit but keeping my crank and rods?

 

custom pistons
accept the slightly lower compression
make up the compression elsewhere (valves, hg, head skim)

(in for fellow brit )

 

u could get the JE 12:5.1 84mm off the shelf, or like stated before get customs
i'd say get 85mm customs

 

If youre going with a stock stroke, dont use the Eagle crank.

 

Ok so thats what I'm thinking too. 85mm customs. In which case i'de be looking at a 1977cc displacement right?

Ok now how much these customs gonna cost. Cp do customs too. I'm sure they will have done this before?

 

Ok combustion. So why would'nt you use the Eagle crank? You seem to be a man who knows his stuff. Also does anyone make a high compression forged piston for this application (stock 87.2 stroke)

 

Because Honda makes a better crankshaft than Eagle.

Look through piston manufacturer's catalogs. Plenty of them make pistons for the application youre looking for.

 

Help me out here man

I'm stuck with the eagle now. My ITR crank is gone. The eagle seems good to me though and was balanced with the rods, pistons, flywheel, clutch and crank pulley I currently have.

If for example I went with the darton kit and bored to 85mm for all motor. Then I bought the 12.5:1 CP pistons for 89mm stroke when mine is 87.2, what compression would I be looking at.

Or Combustion, do you mean I can get an 85mm forged piston off the shelf that is designed to give me the 12.5:1 compression with the stock ITR 87.2mm stroke.

Sorry if I'm being dumb. I currently run 81.5mm toda forged pistons and I'm not used to working out anything up in the 2ltr range

 

The Eagle will probably be OK if you are willing to have some work done to it besides the balancing. In my personal experience, their journal sizes are a bit on the large size and need to be taken down some to obtain bearing clearances usually required for a high performance application.

The difference in stroke will affect the compression, but the only way to tell for sure would be to measure it. CP does alot of custom pistons, if they dont have a shelf one, they can make you one. Email them, or give them a call.

 

Yea dude that seems to make sense. I would'nt be Suprised if CP have had to do customs for this application before anyway. I'll give them a call. As for the Journals on the eagle...The shell sizes were in the mid colous to get tolerance perfect here. Its smooth as butter...

 

It depends what you view as the "perfect tolerance" per the app. It sounds like you got lucky, as I am not the only one who has run into this with aftermarket/eagle crankshafts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">It depends what you view as the "perfect tolerance" per the app. It sounds like you got lucky, as I am not the only one who has run into this with aftermarket/eagle crankshafts.</TD></TR></TABLE>

you are not alone in that matter....

 

Ok what the motor comes apart I'll check shells for wear, but to me tolerance was good in the mid range of shell colours.

What would happen if I took 1.8mm off the head to compensate for the lesser stroke. This was reccomended to me by another forum user. I did'nt like the sound of it personally. If I can get pistons to raise the compression, I would rather do it that way...

Combustion...do you know of anyone with a similar NA set up. I'm running 81.5mm pistons at the minute at 12.4:1 compression at 192whp. What power increase can I expect going up to 85mm?

 

Email sent and no replys...Can anyone else reccomend a piston that has done a similar build

 

u would gain some really nice power goin 85mm. u tried hittin up wiseco

 

Contact our shop in Indy at 888-877-8484. They should have 84mm JE Pistons with 12.5:1 compression in stock.

 

Thankyou. I will try calling next Monday. Just out of interest though, how big can you go on the MID sleeve kit? 85 or 86mm?

 

Can anyone give an answer on the above. I will call darton later though anway.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cyber **** &raquo;</TD></TR><TR><TD CLASS="quote">Thankyou. I will try calling next Monday. Just out of interest though, how big can you go on the MID sleeve kit? 85 or 86mm?</TD></TR></TABLE>

If this a street motor, 85mm.

 

Cheers dude. Been looking at endyn's range of pistons today. It looks like they have some pretty suitable 85mm stock that may work pretty well.

Anyone using their pistons? I would be using them with Toda B spec cams which I already have in a built head.

 

Right, I'm going to go for CP 12.5:1 Forged Pistons and take the Mid liners out to their max 85mm.

Can anyone tell me a good piston to wall tolerance with CP forged pistons and the MID liners. I currently run 0.1mm (metric measurement) tolerance on my Toda pistons with stock sleeves at 81.5mm, and they have been more than fine with no piston slap.

Are tighter tolerance reccomended when using MID sleeves?

If you advise a clearance tolerance, can you please state whether it is is metric or imperial. Being in the UK we normally use metric...But I know in the US Imperial is more common.

 

Go with CP's reccomended tolerance. .003 i believe.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">Go with CP's reccomended tolerance. .003 i believe. </TD></TR></TABLE>

CP recommends 3.5 mils.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mar778c &raquo;</TD></TR><TR><TD CLASS="quote">

CP recommends 3.5 mils.</TD></TR></TABLE>

There is no way on God's green earth CP reco's .140" (3.5mm) piston to wall clearance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">

There is no way on God's green earth CP reco's .140" (3.5mm) piston to wall clearance.</TD></TR></TABLE>

Ok, since you brought God in to this. For Christ's sake, Look at what I said "mils" not mm. Last time I checked, a 1.0 mils = 0.001 in.