ICON 9929 Piston Specs

[skinny z]

It seems I've finally zeroed in on the build direction. Met with my machinist today. I'll be rebuilding the old lump and moving to a 40 over 350 (Gen 1 SBC).
He's suggested the ICON 9929 forged piston from their FHR series.

What I'm finding is conflicting information regarding the compression height.
I've fired off an inquiry to ICON for clarification as well as the weight specs. In the meantime I thought I'd throw out the clarification question here at ST.

The newest info I've found from ICON online lists the compression height at 1.550.
Older ICON catalogs and Summit both list the height at 1.560". There's also a discrepancy regarding the valve relief volume. 3.7cc vs 5 cc.
Does anyone have any recent experiences with this piston?

ICON 1.jpg

Recent catalog.

ICON 2.jpg

Older catalog.

ICON 3.jpg

Summit.

The engine had Speed Pro H631P pistons with a 1.560" height. That makes for a .014" below deck piston combined with a .026" gasket for a .040" PTH clearance.
The newer spec piston will result in a .024" piston below deck. That impacts a lot of things.

[steve cowan]

Kevin,
Do they offer a thinner ring pack?

[maxracesoftware]

i don't know what your Combustion Chamber CC's are ?
i used 58cc and 64cc

they list the Flat-Top Piston's Valve Notches as plus + CC Volume ??
it should be negative CC volume .

SkinnyZ_CompRatios.jpg

[skinny z]

Kevin,
Do they offer a thinner ring pack?

I'd looked into that Steve. The thinner ring pack I was looking for is an option but it looks to be only with a 6" rod version of that same piston.

[skinny z]

i don't know what your Combustion Chamber CC's are ?
i used 58cc and 64cc

they list the Flat-Top Piston's Valve Notches as plus + CC Volume ??
it should be negative CC volume .
SkinnyZ_CompRatios.jpg

I'll get all of my build data together and post it up.

[maxracesoftware]

i don't know what your Combustion Chamber CC's are ?
i used 58cc and 64cc

they list the Flat-Top Piston's Valve Notches as plus + CC Volume ??
it should be negative CC volume .
SkinnyZ_CompRatios.jpg

I'll get all of my build data together and post it up.

SkinnyZ_CH.jpg

[F-BIRD'88]

The latest web pdf catalog I downloaded list the 9929 as 1.55" CH
My older 2008 catalog pdf says 1.565".
The KB hyper flat top is listed as 1.56" KB120.
Does this build really need re boring and new pistons?

[ClassAct]

If all you can get is a 1/16-1/16-3/16 ring pack I’d look for a different piston. There is no reason to run those big, heavy, clunky ring packs. I’d spend more money on pistons and rings and skip the 4 corner cooling. Rings reduce friction and save power. The 4 corner cooling is a fool’s errand.

[skinny z]

i don't know what your Combustion Chamber CC's are ?
i used 58cc and 64cc

they list the Flat-Top Piston's Valve Notches as plus + CC Volume ??
it should be negative CC volume .
SkinnyZ_CompRatios.jpg

I'll get all of my build data together and post it up.

SkinnyZ_CH.jpg

Last build:
Speed Pro 4.030" flat top piston with 5 cc valve relief.
Measured piston below deck at .014" with a 1.560" compression height piston.
Victor Reinz/Mahle head gasket. .026" x 4.125".
.040" PTH clearance.
Measured 65.4 cc combustion chamber
10.2:1

CR 1.jpg

___________________________________


If using the old ICON piston spec and no additional machining other than the overbore:
ICON 4.040" flat top piston with 3.7 cc valve relief. 1.560" compression height.
Piston would maintain the .014" below deck measurement.
Same head gasket (.026" x 4.125").
.040" PTH clearance.
Same heads (65.4 cc)
10.4:1

CR 2.jpg

___________________________________

If using the new ICON piston spec and no additional machining.
ICON 4.040" flat top piston with 5 cc valve relief. 1.550" compression height.
Piston would now measure .024" below deck.
Same heads.
Same gasket for the purposes of this comparison.
.050" PTH clearance.
10.0:1

CR 3.jpg

___________________________________


Of course, substituting the composite gasket for a shim style gasket would recover that .010" lost with the new piston. The heads have the proper surface finish and are freshly milled. The block not so much. It was decked 20 years ago.

[skinny z]

The latest web pdf catalog I downloaded list the 9929 as 1.55" CH
My older 2008 catalog pdf says 1.565".
The KB hyper flat top is listed as 1.56" KB120.
Does this build really need re boring and new pistons?

My catalogues tell the same story although I've a 2011 version as well as the latest 2020 one I could find.

An overbore is most definitely needed. The piston skirts are deeply scratched and the bores are equally a mess. It was surmised by my guy that the lack of chamfer on the bottom of the bores led to bits of metal getting drawn up with the piston.
Not only that, but it's plain to see there's less than zero crosshatch remaining in places. I bet I'll find taper, out of round and barrel shapes when I measure. Not that it matters.

IMG_20220115_115026757.jpg

IMG_20220115_114914613.jpg

IMG_20220115_114849607.jpg

[skinny z]

If all you can get is a 1/16-1/16-3/16 ring pack I’d look for a different piston. There is no reason to run those big, heavy, clunky ring packs. I’d spend more money on pistons and rings and skip the 4 corner cooling. Rings reduce friction and save power. The 4 corner cooling is a fool’s errand.

I read what you're saying (although I think your first sentence might be the reverse of what you mean).
I'd expressed my desire for a thinner ring pack and we'll see how that conversation plays out. So far, other than discussing the basics of what the new short block would entail, nothing is finalized.
We're also dealing with the lack of availability for a lot of these speed parts. It doesn't improve here in Canada either. In fact it's probably worse. The ICON piston is what that builder knows he can get (he was stuffing a block with a set during the course of our discussion).
Not to mention the incredibly poor dollar exchange we deal with.

That said, by most accounts the thinner rings are the way to go. OEMs chose that direction for a reason. I've read about the HP gained through reduced friction, etc. I admire the ease at which an entire rotating assembly can be spun around with only inch/lbs of effort required on the all out Stock and Super Stock engines.
But for a pedestrian guy like me, how much gain is there really though? And at what RPMs? Not that free HP is anything to complain about.

Mentioning weight, the ICON piston (the old version at least), despite being forged and with the 5/64ths rings, comes in lighter at 545/132 for 677 grams than the cast Speed Pro coming out which is 572/159 for 712 grams.
The weight of the ICON piston has yet to be determined officially. There's the .040" oversize to consider as well.
Waiting on my email inquiry.

[mike jesse]

Take a look at the Autotec offering.
#1000104
Ring #AT4040
1.5-1.5-3 MM ring package.
-5cc valve reliefs.
Listed weight is 501 grams.
Listed comp. height is 1.560 in.
Listed comp. is 10.4.

[skinny z]

There'll most certainly be additional conversations regarding the options available.

In those conversations, I'll be setting my CR limit which I prefer to keep at 10.2:1 or somewhat less. Not more.
The weight difference is of some concern as well. It'd be nice if another balance job isn't required if only from a cost perspective. I'm throwing money around at a couple of other projects and if I can save some here and there, I will.

[maxracesoftware]

I'll get all of my build data together and post it up.

SkinnyZ_CH.jpg

Last build:
Speed Pro 4.030" flat top piston with 5 cc valve relief.
Measured piston below deck at .014" with a 1.560" compression height piston.
Victor Reinz/Mahle head gasket. .026" x 4.125".
.040" PTH clearance.
Measured 65.4 cc combustion chamber
10.2:1


CR 1.jpg


___________________________________


If using the old ICON piston spec and no additional machining other than the overbore:
ICON 4.040" flat top piston with 3.7 cc valve relief. 1.560" compression height.
Piston would maintain the .014" below deck measurement.
Same head gasket (.026" x 4.125").
.040" PTH clearance.
Same heads (65.4 cc)
10.4:1


CR 2.jpg


___________________________________

If using the new ICON piston spec and no additional machining.
ICON 4.040" flat top piston with 5 cc valve relief. 1.550" compression height.
Piston would now measure .024" below deck.
Same heads.
Same gasket for the purposes of this comparison.
.050" PTH clearance.
10.0:1


CR 3.jpg


___________________________________


Of course, substituting the composite gasket for a shim style gasket would recover that .010" lost with the new piston. The heads have the proper surface finish and are freshly milled. The block not so much. It was decked 20 years ago.

SkinnyZ_CompRatios2.jpg

[skinny z]

SkinnyZ_CH.jpg

Last build:
Speed Pro 4.030" flat top piston with 5 cc valve relief.
Measured piston below deck at .014" with a 1.560" compression height piston.
Victor Reinz/Mahle head gasket. .026" x 4.125".
.040" PTH clearance.
Measured 65.4 cc combustion chamber
10.2:1


CR 1.jpg


___________________________________


If using the old ICON piston spec and no additional machining other than the overbore:
ICON 4.040" flat top piston with 3.7 cc valve relief. 1.560" compression height.
Piston would maintain the .014" below deck measurement.
Same head gasket (.026" x 4.125").
.040" PTH clearance.
Same heads (65.4 cc)
10.4:1


CR 2.jpg


___________________________________

If using the new ICON piston spec and no additional machining.
ICON 4.040" flat top piston with 5 cc valve relief. 1.550" compression height.
Piston would now measure .024" below deck.
Same heads.
Same gasket for the purposes of this comparison.
.050" PTH clearance.
10.0:1


CR 3.jpg


___________________________________


Of course, substituting the composite gasket for a shim style gasket would recover that .010" lost with the new piston. The heads have the proper surface finish and are freshly milled. The block not so much. It was decked 20 years ago.

SkinnyZ_CompRatios2.jpg

Exactly my results as well.
Now put a .015" gasket in there and the CR gets back to 10.2:1.
So all is not lost if that's the piston that ends up in the engine.
I'll explore my options though.