Looking at these forged pistons...

[jondee86]

These are said to be the CP SC7653 12:1 forgies. 81.5 with 20 dia pin to suit the
smallport 4AGE engine.



Question is... who has used these and how did they work for you ?? And to avoid
turning this thread into a free for all, it would be appreciated that if you haven't used
these pistons, but have a neighbour whose daughter goes out with a guy who used
some other piston in a Honda and it would sh*t all over these... you post your reply in
the FUN TALK forum

Cheers... jondee86

[yoshimitsuspeed]

I don't have personal experience with them but A few knowledgeable people have complained about the topography.
That said, if you decide to buy them hit me up and I'll see what kind of price I can get you on them.
There are a few other options as well.
In about 10 weeks I will have my first set of Supertech 20mm pistons based off the same design I used for mr2tailbreakers build. Unfortunately Supertech was pretty insistent on expanding the pockets to fit their bigger valves. There is still material between the valve relief and the skirt than on the CPs. The Supertech's should be about $450
This is about what they will look like though these were customs from Wiseco. These pistons are non interference on the poncams.

I can't give you a firsthand account of the CPs but I can show you a firsthand account of the above piston.
http://mr2oc.com/showthread.php?t=468649

I can get custom pistons from Wiseco cheaper than the Shelf CPs.
That means I could design you something specifically to your build for a similar price. Note the shape of the cross top on the above piston. That turns the angled part of the cylinder head into some degree of squish area. It's about .5mm more squish gap than the actual squish area has but it's still close enough that it should behave as squish. I also got the edges on the dome about 1mm away from the side of the head making that squish area as well. For 12:1 I would recommend making the valve reliefs as shallow as possible as an interference engine. This will smooth out the topography a lot and give you a pretty sweet piston.

[jondee86]

Yeah... interesting I just spent an hour "skimming" thru that tailbreakers thread...
man, does that guy get into the details !!! Will the Supertech pistons be a full skirt like
the custom Wisco, or will they be a slipper design ? Or more specifically, will they have
cutouts/clearance for the oil squirters in the smallport block ?

Cheers... jondee86

[oldeskewltoy]

jondee...

are you going to be using O/S valves?

I've not yet seen an aftermarket piston that is designed for use with standard valves.... except Bean Bandits, but he had his built with a lower comp height(30mm instead of 30.5)

[jondee86]

... are you going to be using O/S valves?

Early days yet... but I just happen to have an unopened low mileage smallport
sitting in storage, and I am thinking of building something with a bit more snap,
crackle and pop than my current smallport.

I'm more interested in making good torque across the rev range, than having
peak power at some seldom used rpm. I'm thinking around 193-B Kelford Cams,
shimless buckets, lightest flywheel I can find, light pistons, maybe light rods,
ARP rod bolts, OEM head gasket, TRD valve springs and a bit of cleanup work
on the head. I would only consider bigger valves if it could be shown that valve
diameter was going to be a limiting factor to flow at around 9mm lift. I would
be re-using my existing ITB's and management, with an 8500rpm redline.

That's what I am thinking about... I want to build a smallport that revs like a
bigport, but with a bit more torque

Cheers... jondee86

[yoshimitsuspeed]

I would love to see what the 193-b was capable of.
I bet 12:1 would be a pretty good compression ratio to go with them.

Since most of the parts and many of the suggestions for tailbreakers build came from me I offered him a $40 store credit for getting it on the dyno. Now that he got initial numbers I have a secondary agreement for a couple more bucks /hp he makes over his initial dyno.
I feel this info is worth it to me in my effort to expand my knowledge and see real world what various setups can do.
If you would like to do something similar I will get you the best deals I can on parts and offer a similar dyno incentive.
I would be very interested in taking my design and doing a custom piston with minimal valve relief and minimal crown.

[jondee86]

Basically, I have no problem with running an interference engine. And
I do have a preference for a piston top that is as simple and as plain as
possible... so the TODA style with minimum valve pockets looks good.
And I would certainly look at crown and skirt coatings... lightweight
pins and low tension rings. I'm only ever gonna do this once !!!

A little off topic, but you guys may be interested in this engine that
one of our local engine builder/racers is putting together.

http://nzhondas.com/build-threads/155708-1-9l-4age-270hp-build-aka-9age.html

Why ?? Because he can

Cheers... jondee86

[yoshimitsuspeed]

I guess I forgot that you are on the other side of the world. Maybe it won't be so practical for me to supply most of your parts.
Still let me know if there is anything I can do otherwise I'll happly sit back and throw my 2c in. I do wonder what would happen if I asked my distributor if he could drop ship some cams straight from Kelford to NZ haha.
If you are interested in custom pistons I can definitely help with that.

MRP definitely has some awesome stuff but unless you are racing in a class that requires you to go that route I just don't understand dumping that much money into that much power. For probably a fifth or eighth that much you could make more power with a 4AGTE. With probably a quarter that much money you could do a V6 or V8 with that much power. Of course if I made all the parts that were going into the motor I might be more likely to do it too.

[jondee86]

For probably a fifth or eighth that much you could make more power with a 4AGTE.

Bazda from MRP has built a few 7AGTE's... I think he was making something
like 360kW at the wheels at one time. If you have a bit of time to spare you can
take a look at his build thread here...
http://forums.toyspeed.org.nz/viewtopic.php?f=29&t=59730

Yes... I think the 9AGE will be showcasing his stroker kit, and a bunch of other
high performance products he has developed.

Cheers... jondee86

[oldeskewltoy]

... are you going to be using O/S valves?

Early days yet... but I just happen to have an unopened low mileage smallport
sitting in storage, and I am thinking of building something with a bit more snap,
crackle and pop than my current smallport.

I'm more interested in making good torque across the rev range, than having
peak power at some seldom used rpm. I'm thinking around 193-B Kelford Cams,
shimless buckets, lightest flywheel I can find, light pistons, maybe light rods,
ARP rod bolts, OEM head gasket, TRD valve springs and a bit of cleanup work
on the head. I would only consider bigger valves if it could be shown that valve
diameter was going to be a limiting factor to flow at around 9mm lift. I would
be re-using my existing ITB's and management, with an 8500rpm redline.

That's what I am thinking about... I want to build a smallport that revs like a
bigport, but with a bit more torque

Cheers... jondee86

Jondee... without pushing what I do... the simple facts are the 4AG head basically runs flat (flow) @ about 7.2 mm or so. To optimize the 193B's 9mm of lift you really need a good porting job.

A good porting job with 3 angle and back cut will run you about $900 ( €700), add in the cost to do O/S valves, and then port it to those valves and you are well over $2000( €1500)

Plan your head first... once you know what you are doing on the head... get custom made pistons. For the extra $200-$300, you get a far superior piston. I also like the Toda pistons.... but their cost is ridiculous.

I want to build a smallport that revs like a
bigport, but with a bit more torque

see my build

[jondee86]

... the simple facts are the 4AG head basically runs flat (flow) @ about 7.2 mm or so.
To optimize the 193B's 9mm of lift you really need a good porting job.

Good information. So would porting alone get be enough, or would I have to
go to bigger valves ? As you say, bigger valves are a major step up price wise.

I have a "Plan B" Sitting in the shed is a fully worked bigport head that I had
done a long time ago, and never got round to using. If the cost of building a new
engine gets out of hand, then I will look at bolting this to my existing smallport
engine. I'd have to get the chambers CC'd to see what compression ratio I would
get with this setup. I would like to get at least 11:1 to use with existing 272 deg
8.3 lift cams.

I could revert to single throttlebody (ala OST) as I have all the parts including
the T-VIS plate stored away. So a few options to ponder

Cheers... jondee86

[oldeskewltoy]

... the simple facts are the 4AG head basically runs flat (flow) @ about 7.2 mm or so.
To optimize the 193B's 9mm of lift you really need a good porting job.

Good information. So would porting alone get be enough, or would I have to
go to bigger valves ? As you say, bigger valves are a major step up price wise.

I have a "Plan B" Sitting in the shed is a fully worked bigport head that I had
done a long time ago, and never got round to using. If the cost of building a new
engine gets out of hand, then I will look at bolting this to my existing smallport
engine. I'd have to get the chambers CC'd to see what compression ratio I would
get with this setup. I would like to get at least 11:1 to use with existing 272 deg
8.3 lift cams.

I could revert to single throttlebody (ala OST) as I have all the parts including
the T-VIS plate stored away. So a few options to ponder

Cheers... jondee86

you are on the euro boards... you have seen "harke"'s build... Atlantic bits on the inside... ported head (my opinion... my work is superior ) standard valves... 189hp.....


so no you don't NEED O/S valves to make good HP. I'm at a "civil" 165-170 and I'm only twisting to 8000 on standard, albeit with radius back cut, valves.

[yoshimitsuspeed]

So I had another customer come to me asking if I could ship Kelfords to him in Aus. Unfortunately he messaged me on my website then disappeared but not before I looked into it a little.
My distributor wanted to ship them from NZ to their warehouse here in the US then to me to ship wherever I wanted lol so I emailed Kelford and they seemed like very pleasant folk. They said they would be happy to drop ship the cams anywhere I wanted.
So anyway if you did want to go through me for those I sure would appreciate the business. Also of course for anything you would need to order from the US let me know.

[jondee86]

I'm putting this on the back burner again... just need to get a few other
things sorted before I get into internal mods. But I have to say I am leaning
towards custom pistons to up the comp ratio, rather than cutting the head.

Is 12:1 too ambitious for a stock smallport head ? Am I likely to run into
det problems at 12:1 on high octane pump gas ? Most likely I would run these
with my existing 272 deg cams, as I like to change things one at a time, and
see what difference it makes

Cheers... jondee86

[yoshimitsuspeed]

I'm putting this on the back burner again... just need to get a few other
things sorted before I get into internal mods. But I have to say I am leaning
towards custom pistons to up the comp ratio, rather than cutting the head.

Is 12:1 too ambitious for a stock smallport head ? Am I likely to run into
det problems at 12:1 on high octane pump gas ? Most likely I would run these
with my existing 272 deg cams, as I like to change things one at a time, and
see what difference it makes

Cheers... jondee86

12:1 is pushing the limits of my personal hands on tuning experience but with 272s I am quite confident you should be fine.
I mean I am running 7 PSI on 11:1 compression and the stock 250 BT cams. 272s will give you more headroom before getting low or mid range detonation.

[Rogue-AE95]

Bumping this... what happened with those Supertech 11:1 16v pistons with 20mm wrist pins? Will they be suited to run with a stock smallport head, with no need to upgrade the cams?

[yoshimitsuspeed]

I have kind of put this project on hold for a few reasons.

First is an overall lack of interest.
Second is that I learned the 18mm pistons have too small a gap for the rod and when I sent a set to a customer who found this out they told us to machine the rods narrower. They didn't seem to care much at all that their pistons weren't dimensioned properly for stock rods and instead of taking action due to their parts not fitting expected my customer to pay more to have his rods modified.
Although I can make sure this doesn't happen with these pistons it concerns me that they are so lax on QC and taking care of customers.
Lastly I would need to make a large order to get the price down to that of their 18mm pistons. Otherwise the cost is so close to Wiseco or CP that I would rather suggest their shelf piston or even better for just a little more get customs made for your particular build.

[oldeskewltoy]

or even better for just a little more get customs made for your particular build.

truer words have never been spoken.......

[Jimmee1990]

You won't have any issues with 12:1 compression on pump fuel, as long as the tune is quite good and you don't get too crazy with the ignition advance. I have these pistons but in 82mm bore, and using them with a set of TRD Carillo FA rods with the small end re-sized to 20mm, Clive Cams 248A (I think?) 294 total degree, 234 degree @ .050" 8.45mm lift cams.

I'm using a bigport head that has been based off the TRD group A 16v port and developed from there with 1.5mm o/s inlets and 2mm o/s exhaust valves, and all the flowbench tests so far show that the high lift flow is a fair amount higher with low and mid lift flow still having gains over standard valves, albeit on a smaller scale.

So in my opinion, if your only going to do it once the advantage is there and well worth it. Depending on the condition your seats are in you may or may not need to have new seats installed to run this size of valve also which is an added expense. Personally I like the Toda pistons as well, but the price difference is enormous. I prefer CP piston rings also, and in a real world application you probably wouldn't notice a difference between these and the Toda pistons.

[MisterJerk]

12.1 could be too much depending on the overlap of the cams. for reference look up static compression and dynamic compression.

[yoshimitsuspeed]

12.1 could be too much depending on the overlap of the cams. for reference look up static compression and dynamic compression.

I was going to say the same thing but don't get me started on the idiocy of dynamic compression.

[Jimmee1990]

Considering in my first 86 I was running 11.7:1 comp for a while on standard cams and timing and had no issues, as long as the tune is right you'll be fine. That car was a bigport 16v running carbs and a distributor also, and it never pinged as long as I ran good fuel.

[yoshimitsuspeed]

Considering in my first 86 I was running 11.7:1 comp for a while on standard cams and timing and had no issues, as long as the tune is right you'll be fine. That car was a bigport 16v running carbs and a distributor also, and it never pinged as long as I ran good fuel.

First of all the theory still stands. If you could safely run 11.7:1 on stock cams then you could probably run 12.7:1 on some 264s.

Second, if you are going to give generalized advice online you should probably leave enough margin for error to assure they have a safe build or express the proper monitoring equipment and let them know it's not a set it and forget it kind of build. Even if it was for you there is no way to know if it will for them.
What is your premium? Some places get 93 octane or better. Other places get 91. What is your elevation? Running 93 at 4000 feet would be a whole different story than say 91 at sea level.
Due to all the variables you just can't say because it worked of me it should work for you, not unless you know there is so much margin for error that it would be hard to mess up.


With that said I would love to know more about your setup.
You say it was using stock cams and timing but you say it was carbs with a dizzy. Was the ECU still controling spark? if so did it have all needed inputs to not throw it into a safe mode or something?
What octane gas?
What did you use to monitor knock?
How did you determine compression ratio?
What was your compression height, dome and HG thickness? Did you modify the combustion chamber at all? DId you CC it?
Were you on early cams or late cams?

[Jimmee1990]

The ignition timing was a modified 4k distributor, the advance curve was copied off the standard electronic curve so as close to identical as was practical. I was planning on using that as a baseline and re-graphing from there but never got around to it as it went pretty well as it was.
Australian premium which here is 98, which I'm told is very close to if not very slightly better than your 91 in the US due to the different measuring systems/formulas. Premium in NZ is also very close to here in Aus from what I gather also.
Knock detection was by ear, there was no compensation other than changing the jetting and distributor base timing. The tune
I don't have the specs for the piston dome cc or the comp height as this was quite a while ago and that car has long since gone, but the head gasket was a TRD 0.6mm, the head was a modified bigport with a lot shaved off the surface and a lot of port and chamber work but everything was cc'd and measured correctly. The piston were some unknown custom pistons left over from one of my uncles old race car projects, so I can't dig up any specs for them on the net.
The cams were the standard bigport cams to start with, so slightly bigger than smallport. Later I went to a reasonably large grind from Clive cams locally.

The info I gave was a bit general I agree so you're right to question I guess, but also from reading his posts in this and other forums Jondee has a good idea of what he's doing and wouldn't just copy what I've done. It was meant purely as a point of reference. Also worth noting I will be running very close to 12.8:1 to 13:1 on pump fuel with these CP pistons he originally asked about, and both me and the tuner have no issues with running on pump fuel as long as the tune is reasonably safe.