Hi what does the felpro crush down to when torqued up? Tks

Sounds like a good question for felpro.
If I knew the exact material, I could probably look up a stress/strain graph for it.

This will actually be "close" - if no official #'s obtained , take a corner of gasket place in the back of scoobie's mouth , have scoobie bite down hard as he can - get gauges out and measure the "crush" .A Vice does same thing , for head gaskets reach that "limiting squeeze" where it levels off ,and changes little even above the torque spec , under compressive force ; you know where head bolts keep srtetching and stretching till they break under the tensile force.

managed to get hold of felpro and they quoted 48 thou 1.2192mm for us metric dudes. Head has been skimmed by 15thou .381mm outgoing cometic is 1.3mm so looks like compression is going to be raised somewhat. Pistons are 7.6.1 but obviously that dont mean didly, previous person who built the engine proper numpty so who knows what base line was. Going to have to work it out. Apparently melted first time round on first lot of pistons so went for lower compression ones but obviously was bad map. However the vehicle is a bit strange has long headers on the intake and is the altima head rather than 240sx. New HG purchased from rockauto and is on its way to the UK went for felpro also got a block shim just in case clearances dont work out.

I have a head job to do when weather cools down , and in past used Felpro like a lot of people , but I'm willing to try Mahle , or Victor Reinz ater seeing this & other you tubes . See Veggiepower303 , " Felpro Bullsh&T Head Gasket" , he has a couple vids , there's others - CHECK"M WELL those Felpro! Good luck man.

Wow rock auto delivered my head shim today only ordered Monday night arrived some 10days early :-) My gaskets come hopefully tomorrow as they have landed in the UK. Got lucky with the head shim as on it it states which gasket to use and that is what I got :-) Dont know if to use the shim or not with the shim I will be in the ballpark of what I had before or go for slightly higher compression (assume remap required). Got knock sensor and logging on the AEM Hopefully can get hold of the guy who was helping me with the mapping who was also in the states :-)

Shimming the head (or using a thicker head gasket) will reduce compression...

Using a gasket only .004" one way or the other in thickness will not really change anything. And if your shim is only that, or .1 mm. you are really silly as that can blow out easy as spit. A shim that thin then in essence becomes like greasing the head gasket, it stops one side of the thick gasket from biting into the head or block to move around in use. If the gasket is a graphite one you likely failed it using a shim.

You absolutely cannot crush a gasket in a local area (vise) and expect it to be the same crushed thickness as one crushed all over, the unit measure of crush goes up with limited area as it is easier to crush limited area as vs. a much bigger area, the bigger area will not be as thin when done.

On FelPro gaskets..................I used them for many years and up to 13/1 compression ratios on all kinds of racing engines. The parts may have changed some obviously with the world moving to cheaper product. I went to the veggie website video and beyond the thin firering I think the guy is crazy. You do NOT want the firering tight with gasket unused, that gets crushed harder due to not being tight and if you want to stupidly monkey around with the firerings before using the gasket then good luck with that. The fire rings ARE loose before you tighten the gasket up, the torque is what sets them hard in place. That is NOT a mark of a bad gasket, only a bad mech. You need to look for gasket overhang if overboring to make sure the gasket does not protrude into the chamber and if it does then that is mech incompetence at not checking for it. I CAN say we failed Victor gaskets repeatedly back then to never use them again and they will have cheapened out processes as well so beware.

@ PapaSmurf2k3 yes that is what I am saying if I dont use the shim then I will have higher CR.

@amc49 I have had 15thou took off the head, shim is 20thou :-) Just watched his video obviously has some sort of issue with felpro.

Tks

Collected head and confirming chamber size :-) TOmei have it listed as 43cc this head is now 42.55

https://drive.google.com/open?id=1TubjN ... WKcrdZs02k

https://drive.google.com/open?id=1-yU-4 ... G0QS_W47r3

https://drive.google.com/open?id=1Bbvz1 ... q2Hx2ngtjl

So havent bolted the head down yet to calculate the actual CR but if I go on the figures that felpro provided and my shim it comes out as 7.13:1 idiot who threw loads of money at the engine purchased 7.6:1 JE pistons. If I dont use the purchased shim it brings me to 7.34:1



Engine spec as per what previous owner said is below. Note the water injection is not active think he purchased this after the first bad map that melted the sparkplugs after 1 day! He then had it rebuilt with the low CR pistons.

Bored and matched 2.4 KA24DE Block.
Custom JE low compression Pistons 7.6:1
Eagle H beam rods, ARP bolts.
ACL Race Bearings
Balanced bottom end (SRD)
ARP Stud conversion. Head and Mains.
Cometic MLS Headgasket.
Ported & gas flowed head.
BC stainless valves
BC Titanium dual springs and caps
Brian Crower Stage 2 Cams.
Jim wolfe Adjustable Cam pulleys.
AEM fuel rail.
Genuine Walbro 255Ltr Fuel pump
RC 750cc Injectors
Fuel Lab FPR with Gauge
Catch tank
NGK Irid 8’s
Toyo High pressure race oil pump
Bespoke 240SX conversion to largo front timing cover(Allows you to use a 240sx cometic head gasket)
Garrett GT30-76R Turbo
Custom stainless exhaust manifold with 44mm Precision Turbo External wastegate. ( screamer )
Full Stainless 3” custom free flowing turbo back Exhaust.
Full custom 2.5” stainless steel intercooler pipework with AEM water/Meth injection.
AEM Water meth injection system with tank sighted under the bonnet ****NOT IN USE***
AEM ATS
AEM 3 Bar Map Sensor
AEM Series 2 Stand alone ECU with custom wiring loom. Mapped by Dan @ Advanced Motorsport. Achieved 422Whp 483Ftlb Max torque 3400Rpm @1.5 Bar.

Holy moses that's some low compression.

Yeah, why so low?

I built a turbo KA and raised the compression over stock. That was nearly a decade ago and it's still running well over 500whp.

Who knows if it's possible to salvage such low compression with Turbo , or ANY boost ? Scooby deserves whatever help we can suggest here Like -it's gonna either be induction to get it going or going "down " to rebuild / redesign heads on down to lower end / rotating assy -pistons ?
Valves / timing irrelevent , immaterial ,and most likely moot here - in the end just don't " valve into pistons " .

Inherited the stupid design, the pistons volume is 44.44cc. The head is an altima spec car was previously on higher CR pistons but that engine lasted 1 day. Here is a dyno graph and picture of what we are dealing with.

https://drive.google.com/open?id=1VgW0K ... iSPpKbbIos

https://drive.google.com/open?id=169N-9 ... -eDmHkxe-C

https://drive.google.com/open?id=1Y0fmW ... 8f9u_tSC-Y

https://drive.google.com/open?id=12Mn1D ... jMhDWA-Mmc

Multiple posts -sorry. Car actually drives ok. Seems to have been built like how turbo'd cars in the 1980's would have been.

Last multiple post edit. It is a MPV/minivan has an autobox as well. Think 300kg heavier than a 240sx. Any help much appreciated. I have found other posts on other sites where they were questioning the map around how retarded the timing was. Can post my spark table for you guys to check out if you want?

Here is a picture of the combustion chamber when I was cc'ing it not sure how much if anything has been removed from here cannot be much if anything as the cc was with 1 of factory

https://drive.google.com/open?id=1TubjN ... WKcrdZs02k

And here is getting tdc

https://drive.google.com/open?id=17Ll7M ... tstffzAjaP

An old school supercharged compression ratio for back in the days with not as good a computer and narrow band only O2 sensor and no intercooler. It means you can bump the boost up higher. Better if the turbo is a smaller one with less lag to spool up quick, it makes up for that as does advancing the intake cam. Even more reason not to use the thin shim if clearances are OK.

That is the weirdest intake setup I've ever seen.
Looks like boost hits like a damn sledgehammer though.

Forget what I said about the turbo type there, it is likely wrong. With 7.5 compression it's more like used with a constant mechanical supercharger rather than an on again off again turbo.