View Full Version : f4r piston fitment
hi can anyone tell me if the pistons in the f4r (172) engine are pressed on or held in place with a c lip
Only thing i cán tell is that the forged pistons for F4 & F7 are the same so i guess they are held by a C-clip too..
As Tutur says they are C Clipped in :D
the same ? No way.
We fitted F4R wossner's (low comp) into the F7R700. You get a cr from 7.1:1
Lol, aren't the same then!
Would be fun for guys wanting to run epic high boost though :P
Wat would f4r pistons fitted in a F7R do with comp.? Sounds interesting!
Glenn's engine, calculeted the whole thing, skimmed the deck (0.6mm) icm with 1.6hg and skimmed head and now its got 7.8:1
He's gonna run the GT3076R, no idea on the boostlevel (yet).
the same ? No way.
We fitted F4R wossner's (low comp) into the F7R700. You get a cr from 7.1:1
Are you sure your not confused with another engine as I have a machined 172 piston (was in turbo'd 172 engine) on a bent rod and it has C Clip I will find pic of it and post up :D
here's a pic you can see the C Clip and the indent to take the C Clip in and out this is a 172 phase 1 piston and rod (not sure they changed design on the newer models)
http://www.rtoc.org/boards/picture.php?albumid=1430&pictureid=4211
i'm pretty sure...unless i was drunk when putting it togheter. :wink:
F7R700 williams b.e
F4R730 wossner low comps with pec rods
and to make it more fussy, got a 215 clutch on the williams flywheel.
I stated that F7r forged pistons are the same as f4r ones, thats not correct and thats what Jo is trying to say.
Ideal solution for high boost applications Jo although i doubt it has to be thát low...
no worries, i'm not gonna start a discussion.
I've got no idea what the correct english word is for the CR measurment, in dutch its 'uitlepelen' wich took 2.5h brainstorm how much the deck-skim (bottom-end icw head and hg) was.
Tutuur: oem williams comp = 10.0:1 , RS172= 11.0:1 If you gonna use F4R pistons they prob. need more gap for the valves. I didnt compare N/A oem pistons, only forged ones.
volymmannen
28-01-2012, 19:58
no worries, i'm not gonna start a discussion.
I've got no idea what the correct english word is for the CR measurment, in dutch its 'uitlepelen' wich took 2.5h brainstorm how much the deck-skim (bottom-end icw head and hg) was.
Tutuur: oem williams comp = 10.0:1 , RS172= 11.0:1 If you gonna use F4R pistons they prob. need more gap for the valves. I didnt compare N/A oem pistons, only forged ones.
there is at difference in comp height F4R 30,2mm F7R 30,7mm the rods are the same, cant understand how you get so low CR
sideways danny
29-01-2012, 02:47
f4 and f7 pistons are not the same. They fit the same but the crowns are very different. F7 low comp pistons are already too low comp in my opinion, giving about 8.5:1. I worked out using F4R low comp pistons in an F7R would give around 8:1. I would go no lower than 9:1 if i was building a turbo'd F7R now
What do you think would be max power to go on 9:1?
sideways danny
29-01-2012, 16:24
doesn't work like that really. dropping the compression very low is an old fashioned approach, as is using excessive fuel as a combustion coolant. much better ways to avoid detonation that just retarding the ignition (which raises combustion temperatures)
Advancing past detonation (in the mid range revs) is actually safer in a lot of instances as temperatures stay lower and you dont risk melting pistons. You also make the car a lot more responsive. The key is working out what the detonation trigger is at each point.
Well there will be a theoreticle ceiling right?
Although i've seen a 800hp civic with 9:1 so 8,5:1 willbe low enough for every wish i think.
I've machined f7r pistons and cr is now 9,2:1. Max power will be limited by the deck thickness i think. At it's thinnest point it's 7mm
OK bit of a stupid question I am now building an F7r turbo setup and am considering using the f4r piston but want to confirm what the compression would be for the following:
Standard F4r piston in f7r block (non skimmed),
What skimmage would I need to take of f7r pistons for 8.5:1 compression?
What smikkage would I need to take of f4r pistons for 8.5:1 compression?
Cheers for any info
You're building an engine again? :D
Give me the piston measurements and i'll be able to calculate it for you...
Especially the height off the pin cause that's different as told on here...
You're building an engine again? :D
Give me the piston measurements and i'll be able to calculate it for you...
Especially the height off the pin cause that's different as told on here...
Yeah got a valver hybrid plan is to turbo f7r same spec as before but with intercooler this time around as it had more than enough power for my needs as before.
I will try and source some f4r pistons and see if I can get hold of an f4rt piston aswell
Well there will be a theoreticle ceiling right?
Although i've seen a 800hp civic with 9:1 so 8,5:1 willbe low enough for every wish i think.
I've machined f7r pistons and cr is now 9,2:1. Max power will be limited by the deck thickness i think. At it's thinnest point it's 7mm
Civics get away with running big CR because they are turning so many revs, at higher rpm the piston is moving a lot faster so there is less chance of the flame front out accelerating the piston.
Some of them run over 10:1 and big boost when they are really revving it.
To answer the original question, the F4R pistons have clips and a fully floating pin. (ie it can spin in both the rod and the piston)
Ok Just to revive this thread as I have a few question's, got an f7p now not an f7r, but I also have a nice selection of pistons to use :D
I have some 172 high comp wossener forged pistons which I was going to either sell on or skim them down, and I also have some standard 172 pistons and rods, oh and I have 3 low comp f7p pistons which I am struggling to get a 4th due to factory delays.
My question is what compression would standard f4r pistons lower an f7p engine to.
I would of thought they were a bigger bore then an F7P so wont fit?
I would of thought they were a bigger bore then an F7P so wont fit?
I am going to be boring out the block anyway as I also have low wossner pistons for an F7p but 83mm jobbies, I am trying to keep my options open. I believe peeps use them in f7r's
They will not fit standard f7p without a bore to 82.7 but will drop straight into f7r :D
the same ? No way.
We fitted F4R wossner's (low comp) into the F7R700. You get a cr from 7.1:1
Are you sure your not confused with another engine as I have a machined 172 piston (was in turbo'd 172 engine) on a bent rod and it has C Clip I will find pic of it and post up :D
here's a pic you can see the C Clip and the indent to take the C Clip in and out this is a 172 phase 1 piston and rod (not sure they changed design on the newer models)
http://www.rtoc.org/boards/picture.php?
albumid=1430&pictureid=4211
I am sure my link won't work for the above so here is my current project f7p turbo, this is using f4r rods with wossner 83mm low comps
http://i252.photobucket.com/albums/hh25/GTTJames/SAM_2957.jpg
Why f4r rods mate?
Apparently stronger than the f7 jobbies, I have seen f4r conrods' sustain high revs and finally give out around 450bhp
here's a pic of the f7r rod on left and the f4r on right
http://i252.photobucket.com/albums/hh25/GTTJames/SAM_2951.jpg
Hhhmmm according to Scoff the F4's are piss...
Seen a bent rod on a stock f4r engine too, however i can't recall what the reason was.
volymmannen
13-05-2012, 17:16
Heres a picture on my standard megane f7r rod and a not standard rod :lol:
http://i55.photobucket.com/albums/g159/volymmannen/DSC00475.jpg
I don't see the difference :lol:
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