P73 Vs. PCT Pistons


Championship White

Championship White

Ex EK9 Rx Owner
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Jun 21, 2009
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I bought an engine off of my brother as when we measured the stroke it turned out to be a 1.8 and he wanted a 1.6. It has B16b pistons in it I believe from what I can see through the spark-plug hole, though it's a bit coked up inside. It was also running a mappable ECU when imported with a standard head so I'm pretty sure it must be PCT pistons.

I'm going to strip it down and rebuild it with OEM parts, but was wondering if I should retain the PCT pistons or swap to P73 pistons. I've researched this question and there are quite a few mixed opinions and not a lot of facts.
 
opinion is that you get a better flame front with P73s although I used PCTX with no issues and the engine makes good power - have 4 P73 81mm if you want them cheap? only done about 40k
 
I have read and been tolled that PCT`s are not 100% safe, but gives extra bhp from the high compression, what i would look into would be any weight difference between the two.
 
Pct pistons are a good bit heavier than p73 pistons and there design isn't ideal for high compression so if I were you I'd go with the p73 pistons or some proper aftermarket pistons designed for high comp.
 
Vtec6000 said:
Pct pistons are a good bit heavier than p73 pistons and there design isn't ideal for high compression so if I were you I'd go with the p73 pistons or some proper aftermarket pistons designed for high comp.
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don't want to sound pedantic, its a genuine question, but do you have real world experience of this or are you just going by what you've seen on forums?

so often I read this with little actual evidence to prove, agree with your point about aftermarket forged pistons, but hey every build has a budget :lol:

having compared graph for graph on the same dyno, i'm glad I stuck with the PCTX
 
pimpinblackcivic said:
don't want to sound pedantic, its a genuine question, but do you have real world experience of this or are you just going by what you've seen on forums?

so often I read this with little actual evidence to prove, agree with your point about aftermarket forged pistons, but hey every build has a budget :lol:

having compared graph for graph on the same dyno, i'm glad I stuck with the PCTX
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That's no problem its good to question things in a bid to understand:nice:

Ok so how much power did you make over a b18c with p73 pistons?

You have to take in to account some engines simply make more power than others due to been healthier or having mods that are better complementing of each other etc. For example my b16b with only intake and decat made 175bhp on stock ecu on a dyno dynamics and I no from other dyno graphs on this particular dyno b16b's with more mods to list have made less power even though internals are the same in each engine so my point would be just because you made more power than a b18c with p73 pistons doesn't mean its the pct pistons that gave you that extra power.

And yes the pct piston is 17g. heavier than a P73 piston and iirc there actually the heaviest of all oem b series pistons.

PCT pistons fitted in a b18c are going to give a comp ratio of high 12's which is on the high side especially if your limited to 95ron fuel in your area and tuning would be necessary to keep it running safe.
My advise would be if you want to go high comp do it right by buying pistons designed for high comp application. If you can't afford pistons then you probably can't afford to buy aftermarket cams to make use of the extra compression so what's the point for the sake of a few hp? and then if you do decide further down the line to get some high lift/longer duration cams there's a good chance your going to have V2P clearance issues with those pistons unless you machine the valve reliefs deeper which is more costs.... Fair enough if you made some gains and are happy with the power output but for me personally if I was putting together a engine to be of that compression ratio i'd be hoping for substantial gains which won't be had by pistons alone:nice:
 
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The engine I have seems to be very washed out on the intake side, there must have been alot of fuel being dumped in and the head is very coked (though it may be due to the start stopping on getting it shipped over). I thought it might have been overfueled to stop hot spots on the PCT piston? Or it could just be a rubbish map.

Pimpin do you have the graphs on hand? And what did you use when rebuilding the engine - all OEM etc.? Any issues with the engine? It would be a great resource for people looking for the same answers later on.
 
pimpin is running a wild set up of buddyclub spec iv cams and b18 bottom end and Henry who tuned said it was an immense build! I think its runnin 220bhp but I'm sure he will be back on to expand! :) Its been going perfect for months now!
 
vtec6000 - some interesting points there, freshly rebuilt engine so takes a lot of the variables out, what I meant was on the same dyno i've seen a freshly built itr engine make less power/torque figures...plus its run and mapped on 99 ron so no det issues

championship white - will dig out my spec but a mix of oem and aftermarket parts, bottom end is almost all new oem parts except the ACL race bearings which my crank was sized to once it was ground and micropolished, sounds more like a poor map but would be interested to see if it is borewashed causing the coking.

rambo - cheers mate, 5k in and still going strong
 
can't find my graph but i'm heading back to my tuner soon to get my map checked as i've just fitted a fujitsubo rm01a so will get one for you then, was originally 220bhp/140ftlb spec below:

B18C block from 98 spec JDM ITR overbored .25mm
Mapped on Crome Pro by Henry Roy/
Agra Race Engineering built B16a2 head with 3 angle valve job, port and bowl work and new valve guides
Buddy Club titanium retainers
Buddy Club valve springs
Buddy Club Spec IV cams
Skunk2 cam gears
Gates extreme timing belt
ITR valves
EK9 PCTX pistons .25mm o/s
ITR rods
ITR oil & waterpump
ITR Crank reground and micropolished
ACL Race Bearings .25mm o/s
ARP head studs
Cometic head gasket
Hondata inlet manifold gasket
5Zigen 2.5" ITR Manifold
DC Sports decat
Fujitsubo RM01a 2.5" exhaust
ITG CAI
ITR Throttle Body
AEM fuel rail
B&M fuel pressure regulator & gauge
MSD distributor cap and blaster external coil
Koyo ITR double width rad with aircon removed
Samco rad hoses
Spoon rad cap
Spoon thermostat
Spoon reservoir covers
Spoon kevlar plug cover
Skunk2 vtec solenoid cover
Greddy oil cap
Carbing rad cooling plate
B&R Fittings Engine Breather Kit to replace stock PCV system
Unorthodox Racing crank, p/s and alternator pulleys
Fidanza flywheel
Exedy stage 1 clutch
J's Racing engine torque damper
Energy Suspension poly engine mounts
Energy Suspension poly gear lever mounts
12.5:1 compression ratio
 
pimpinblackcivic said:
can't find my graph but i'm heading back to my tuner soon to get my map checked as i've just fitted a fujitsubo rm01a so will get one for you then, was originally 220bhp/140ftlb spec below:

B18C block from 98 spec JDM ITR overbored .25mm
Mapped on Crome Pro by Henry Roy/
Agra Race Engineering built B16a2 head with 3 angle valve job, port and bowl work and new valve guides
Buddy Club titanium retainers
Buddy Club valve springs
Buddy Club Spec IV cams
Skunk2 cam gears
Gates extreme timing belt
ITR valves
EK9 PCTX pistons .25mm o/s
ITR rods
ITR oil & waterpump
ITR Crank reground and micropolished
ACL Race Bearings .25mm o/s
ARP head studs
Cometic head gasket
Hondata inlet manifold gasket
5Zigen 2.5" ITR Manifold
DC Sports decat
Fujitsubo RM01a 2.5" exhaust
ITG CAI
ITR Throttle Body
AEM fuel rail
B&M fuel pressure regulator & gauge
MSD distributor cap and blaster external coil
Koyo ITR double width rad with aircon removed
Samco rad hoses
Spoon rad cap
Spoon thermostat
Spoon reservoir covers
Spoon kevlar plug cover
Skunk2 vtec solenoid cover
Greddy oil cap
Carbing rad cooling plate
B&R Fittings Engine Breather Kit to replace stock PCV system
Unorthodox Racing crank, p/s and alternator pulleys
Fidanza flywheel
Exedy stage 1 clutch
J's Racing engine torque damper
Energy Suspension poly engine mounts
Energy Suspension poly gear lever mounts
12.5:1 compression ratio
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nae worries lad!! that is an epic spec which I am very jealous of mate! :p glad its going all good after 5k! :drive:

could you post up pics in the photos section of your B&R breather kit? sorry for spamin this thread btw!
 
FWIW, from the reserach that I've done through reading books and tech articles your avg. WHP gain is ~3% for every point of C/R increase.

For example:
Stock JDM ITR C/R is 11.32:1 with P73 JDM Pistons (According to ZealautoWerks)
Using PCT's would bump it up to a pretty high 12.73:1. Thats a pretty high C/R for a street car on pump gas.

Using the Factory HP figures it'll be 197hp with the stock 11.32 C/R and would "theoretically" bump the power up to 205hp using the PCT's with a C/R of 12.73. Now these are only theoretical figures so to speak but it's just a general idea.
 
hahah thats only the engine mate, should see the full shooting match, would make my bank balance weep if I added what was spent on this car!

no clearance issues at all, the head has had a cleaning skim off it as well, would need to root about for the clearances as I can't mind them off the top of my head but they were checked a full 4 degrees either way at the cam so I had plenty leeway to dial them in properly, which my tuner did for me. He said at the time that nearer 230 would be achieveable at the compromise of the idle, but mines is a daily driver and idles like stock, plus it wasnt built with the intention of peak number chasing anyways,so i settled for 220! the torque is a good linear delivery through the revs and picks up a lot better than a stock engine, so all in all i'm happy.

henry roy mapped dunsys old spoon stroked ek9 which made 212 bhp on the same dyno, so I think the numbers it produces are pretty accurate, that said I was more interested in how it drives!
 
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Sounds like a great build, I guess you just run it on something like V Power? What CR did you end up with?

And thanks for all the info :nice:
 
Thats interesting. What are the specs of those cams i.e duration and lift?
 
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