Custom 89mm forged piston with pin height to suit L24 rods on L28 crank

[d3c0y]

Has anyone ever ordered pistons similar to this spec and how much did it cost?

 

Is the displacement & rod to stroke ratio worth the effort over a .040" overbore with standard L28 rods?

 

The engine will be running Mikuni 44s with 40mm chokes, high lift cam .580" kind of region, ported E88 with light weight bigger valves hoping for 8k - 9k rpm.

[ozconnection]

Try these guys.

 

http://www.zccjdm.com/catalog.php/azcarbum/dt43033/pd958165/L6_L28_STREET_PISTON_KITS_KAMEARI_L20_L28_

 

And if you ask what about L24 rods, L20 and L24 rods are both 133mm long.

 

That's going to be an expensive engine to buy, build and develop. Wow. Good luck. 

 

Oh dang...they're cast.

 

I used JE forged 300ZX Turbo pistons and had the rods custom built instead. Buy 'em and run 'em is the advantage to using stock L Series rods in this application where basically everything you use will have to be modified to some degree to run up to 9K rpm. My RSR is now 1.73 with my 136.5mm rods and standard stroke L28 crankshaft. 

[NZeder]

not so much oh dang for cast. I had a set of 90mm in the same setup once - L24 rods on L28 crank. They were cast and only 40g heavier than a mates forged JE 87 units. They were some of the nicest cast pistons I have even seen.

 

Mine were out of Japan - and were old Tomie items (that is correct Tomie not Tomei they were new old stock)

[peter mc]

even better custom fj20 rods from spool about $600 and sps pistons 88mm =$1500 is a grate combo revs much nicer

sps has made this combo for me in flat top and dome top +15cc for p90a head killer combo 9000rpm

[d3c0y]

When i say 9000rpm i dont mean for long periods. 8k-8.5k would be normal operation of longevity's sake.

 

NZeder: From what i've read cast pistons are too weak for high rpm, or is that just factory cast pistons? And for $1100USD, its pretty much the same price as Peter MC's custom forged slugs.

 

I just did another search and found that JE will do the pistons i want for around $900 - not too bad.

 

My question hasnt really been answered though. Is there an noticable power difference going from 87mm to 89mm pistons?

 

I would like to get out of buying aftermarket rods if i can and just prep a set of factory ones, i already have the 9mm arp bolts for them.

It would be awesome to get 6 stock FJ rods and prep them. Probably be pretty hard work these days.

I was going to put the money into pistons and head development instead.

 

Peter: why not go the 89mm bore?

 

 

[NZeder]

87 vs 89 ok.

 

1. Not sure if the rules are the same in Oz but for some classes of racing here in NZ a max over bore of 1.5mm is permitted so that is a good reason for going 87mm or 87.5mm only on a L28 block.

2. Going smaller = more room to grow/rebuild on the same block

3. More meat in the bores

 

Re the power levels and high RPM

Power is from the head yes the bottom end needs to be up to the task and the extra CC from the bottom ends = you don't have to spin it as hard to make the same power. But a well build 87 or even stock bore can yield some impressive power numbers.

 

Forged slugs are better for sure and if I was doing it I would go forged items - I only had those Tomie cast slugs as I got them for the right price at the time (RRP on them was $800 USD but I got them for less than 1/2)

 

Re the comment about factory prep rods vs aftermarket

1. I would not prep factory items again

2. Aftermarket H-beam are lighter (will help with your higher rpm requirement)

3. Aftermarket units come with ARP fasteners

I say this as by the time I prep my last set of rods, shot penn, balanced, and new bushes (I used RB30 little end bushes as they are a good bush - but that mean some machining costs to the little end = would have been better to just get aftermarket items from the start) the cost was about the same as new lighter H-Beam aftermarket items but I was still using some 30year rods???

 

If I were you - do as Peter has - new aftermarket H-Beam rods (be they FJ or L24 replacement - check out maxspeedingrods for L24 rods as a good price) and forges slugs - you will not have to worry about the bottom end if the rest is done right - then if racing and budget allows it every few seasons work on head development to get better HP each season there is still a lot to learn about getting power from a L6 head

 

[d3c0y]

That's awesome thanks - answered all my questions.

[ackent1]

This place is worth a look  www.pureperformancemotorsport.com

I have got some rods from PPM                 

I am waiting on the Forged dome pistons they where at bit cheaper than SPS and they run tighter clearances 4032 aluminum, coated etc, they will do any design you want 

 

[peter mc]

hi 88mm is a compromise . 89 is better for flo than 88 but bore flex is a problem . ring seal is very inportant for torque .I flow my heads on a 88mm spacer  . so no to cheat. the fj stock rod is very heavy i think it is over 700g to heavy for a race engine .the spool rod is 590g and very strong . the other thing is the rings on sps piston is a 1mm  1mm 2.5 mm which is good for a few hp and every bit helps

[peter mc]

yes there are better pistons than sps which have 3 th clearance but they are in melb  and they have made the piston to go in to the chamber for me with grate results

[d3c0y]

Next question is what happens as the pin height gets closer to the top of the piston? Is there a pin height that is too low?

 

Because you could use VH45 rods and get an even better rod to stroke ratio with 147.32mm rods

[peter mc]

140center is about as far as you can go. you have to have rings .which is the problem as the pin gets closer to the oil ring

[NZeder]

88mm is you are allowed to run 88mm is a good step - this gives you the bore clearances for larger valves as Peter state - more flo and at the end of the day an ICE is just a big air pump - with a bang in the middle Peter has cover all other details in his post above. Good luck with the build.

[bryan3976]

even better custom fj20 rods from spool about $600 and sps pistons 88mm =$1500 is a grate combo revs much nicer

sps has made this combo for me in flat top and dome top +15cc for p90a head killer combo 9000rpm

 

were can i get that stuff from do i order it trough u or a shop

[peter mc]

spool inports for the rods ask for 6 fj rods you can find them on the net. the pistons you can ring sps or i can for you as they are custem he has all pistons on file so not a problem. if you have a problem give me a call

[bryan3976]

there inHammond Rd, Dandenong right

im going to drop my block off tomorrow at dandenong re bores  on the same road so ill drop in