what is the piston compression distance for the fiero summit racing have a 1.599 and a 1.578inch piston compression distance these pistons have a 1.599 inch compression distance these pistons have a 1.578 compression distance also since they are kieth black they have parts numbers that have c's like this UEM-1463C-5MM then some have no C..... UEM-1463-5MM i dont know if this matters or what but both the 1.578 and the 1.599 have parts numbers that look like the same product except one of the two part numbers will have a C and the other wont.
Be sure to find out your intended head gasket compressed thickness. Then aim for the compression ratio you want, which will determine your grade of gas once the job is done. Many other factors, but at least compare stock components to your aftermarket selections. I personally would be annoyed with a 2.8 running premium gas
Compression distance is the height from the center of the wrist pin to the top of the piston. You should be able to measure that on your existing pistons. That said, I think the taller ones are for the engines with 8.9:1 compression, and the shorter ones are for the engines with 8.5:1 compression. The Fiero V6 uses the 8.9:1 pistons.
The C in the part number probably means the piston has an anti-friction coating. That's what that black stuff is on the side of the piston. The anti-friction coating is a good thing. Get it if you can.
I personally would be annoyed with a 2.8 running premium gas
Agree - unless this is part of a build that also significantly increases flow through the head, the added compression will get you not much except higher fuel cost.
ok so the higher pistons run a 8.9cr and thats what the fiero runs would a metal head gasket affect my compression ratio ? edit also the pistons are cast alluminum dont know if this is good or bad
[This message has been edited by Eltsyrk (edited 02-25-2018).]
If the head gasket thickness is different from stock, then yes it will affect the compression ratio. (stock head gaskets are 0.040" thick) But 8.9:1 is pretty low by modern standards. And the 2.8 V6 has plenty of clearance between the pistons and the heads. Even the thinnest Cometic MLS head gasket (0.027" thick) will leave you with plenty of clearance.
Edit to add: and if you're doing a performance build, then you might also want to deck the block to get the optimal quench height. If you shave 0.010" off the block deck (and use the thinnest MLS head gaskets), that will get you pretty close. It will also get you 9.5:1 CR.
Also, cast aluminum is the standard material for pistons. For most people, cast pistons are fine. But if you're building a high-compression or boosted engine, then you need forged pistons.
[This message has been edited by Blacktree (edited 02-25-2018).]
Get the pistons that will get the piston level with the surface of the block ("zero deck height") then use a head gasket that will give you 0.035-0.040" piston to head clearance, very close to the ideal quench height. That will give you the highest compression ratio and also make the engine less sensitive to octane.
Anything more than about 0.060" piston to head clearance will reduce the quench effect, which will also make the engine more susceptible to detonation (pinging). One big mistake when specing an engine is to reduce compression by moving the piston down the bore. A fuel injected engine should easily handle 9.5:1 on 87 octane with the correct quench.
Edit: changed to more closely reflect what I should have stated, which is what Blacktree just clarified.
[This message has been edited by mender (edited 02-26-2018).]
AFAIK, there aren't any off-the-shelf pistons for the 2.8 V6 that will get you zero deck height. The closest you'll get is with the 8.9:1 pistons, which are 0.026" below the deck. That's why I suggested thinner head gaskets and decking the block. Because that'll be cheaper than having custom pistons made.
what is the piston compression distance for the fiero summit racing have a 1.599 and a 1.578inch piston compression distance these pistons have a 1.599 inch compression distance these pistons have a 1.578 compression distance also since they are kieth black they have parts numbers that have c's like this UEM-1463C-5MM then some have no C..... UEM-1463-5MM i dont know if this matters or what but both the 1.578 and the 1.599 have parts numbers that look like the same product except one of the two part numbers will have a C and the other wont.
Eltsyrk, it really depends what you are building the engine for. Are you just rebuilding a old tired engine to get it back to running as it did originally or are you rebuilding it to get more performance out of the engine? Looking at Engine Tech which is a great resource for OEM engine rebuilding parts they list the 1.578 CH for 80-86 iron head 2.8 engines and the 1.599 CH for 87-89 iron head 2.8 engines. Here is a link to their catalog page for the 2.8L.
Cast pistons are fine for any stock to mild performance build. you only need to worry about going to hypereutectic pistons if you want to start throwing some boost or spray at it and forged for more extreme amounts of boost / spray / extreme high compression.
------------------ Fiero's Owned:
1987 Coupe 2.5 5spd May 99 - June 03 1987 GT V6 5spd July 30 2012 - Current
[This message has been edited by Fastfiero1 (edited 02-28-2018).]
The engine build is mostly valve train with an internally balanced crankshaft I’ll be running a 260h with 1.6 rockers and after market headers and intake no boost no spray also if I run the 1.599 pistons with a felpro steel laminate head gasket increase my cr to a point where I would need high octane which Is something I would like to avoid I do beleave the head gasket is .030 compressed I currently have no access to my cart on summit so I can’t give any details on what head gasket thickness is on that felpro for the 2.8 ------------------ 1986 fiero se 2.8 v6 4 speed
[This message has been edited by Eltsyrk (edited 03-01-2018).]
The engine build is mostly valve train with an internally balanced crankshaft I’ll be running a 260h with 1.6 rockers and after market headers and intake no boost no spray also if I run the 1.599 pistons with a felpro steel laminate head gasket increase my cr to a point where I would need high octane which Is something I would like to avoid I do beleave the head gasket is .030 compressed I currently have no access to my cart on summit so I can’t give any details on what head gasket thickness is on that felpro for the 2.8
OK, so based on that, cast pistons are just fine and I would not waste money on anything beyond that. If you are getting the 260h be sure to also do the supporting mods with it like better springs, etc. I would recomend just getting the complete kit from comp which comes with everything (Comp part# K16-233-4)
Also I think standard head gaskets would be fine as well but if you want a metal gasket and something you can get in stock thickness or any thickness you want WOT-tech.com has the Cometic MLS head gaskets Here. They are good but very pricey.
I have got all the valvetrain already purchased it’s all comp cams so far the only parts I don’t have that I need are pistons rings valve seals and retainers
Gotcha. Well the comp retainers that match your cam kit are Part# 742-12. I'd recommend those or another good strong retainer set. The higher compression height pistons would bring you up to 87-88 Fiero 2.8 specs. Sounds like a nice little build.
[This message has been edited by Fastfiero1 (edited 03-01-2018).]
I'll give you a set of good used Comp Cams 742-12 retainers for free, if you want them. I recently put a really aggressive valvetrain in my 3.4 V6, so I can't use the "normal" valvetrain parts anymore. I also have some Comp Cams 980-12 springs, but it looks like you have that handled already.
[This message has been edited by Blacktree (edited 03-01-2018).]
Originally posted by Fastfiero1: The higher compression height pistons would bring you up to 87-88 Fiero 2.8 specs. Sounds like a nice little build.
I wouldn't consider the parts replacement catalogs too seriously. Early Fieros actually had higher horsepower ratings than later Fieros.
I think that all V6 Fieros had pistons with similar specs.
In terms of head gasket thickness, one issue which has not been mentioned is that deviation from stock may cause fitment issues with the intake manifold, requiring further machining to correct. So be on the lookout for this.
The Fel-Pro 512 SD to my knowledge is MLS, if my understanding of what constitutes an MLS gasket is not wrong. You don't have a selection of thicknesses, however.
Cometic MLS, and felpro, are the only two head gaskets I would consider at all. MLS gaskets are the most foolproof you can get, but the idea is mismatched metals. Iron block/aluminum heads. The heat expansion differences are what promote MLS gaskets. If fel-pro offers a gasket to suit your compression height with iron heads, go for it.
Cometic was my only option on an iron block/aluminum head build that offered the compression height I wanted, so I paid the premium for that build. Your mileage may vary.
The engine builder I sent my engine to only wants me to use brand new parts in this engine sadly he has already tried to get me to replace the engine block which has less than 30000 miles on it. But Im grateful for the offer on the retainers I actually am running the same springs you have and more than likely the same retainers I have a question though the difference between 10 degree and 7 degree retainers for this engine and bonuses or negatives?
I have got all the valvetrain already purchased it’s all comp cams so far the only parts I don’t have that I need are pistons rings valve seals and retainers
