sonypete

Well Guys I posted way back(I think) with a rod knock and just now getting my engine rebuilt. Decided to go turbo and got LC forged pistons and just about everything els eto rebluid my engine. Well the pistons turned out to be lower then the 8.5:1 compression. I had planned on building my motor in two steps. First = bottom end built for massive boost and run it N/A for a couple months. Second stage = get new head and build it up for massive boost slap it on along with turbo and everything needed. Well 8.5:1 was pushing it for N/A since it would run a bit slow off the line, well 8.15 is gonna be reall bad hah. Since I was gonna chuck this head any ways for the second stage of the build up, I wanted to know how much compression would I gain from say decking the head about .020" or maybe .030"?? The piston top are lower so valve clearance should be okay(will check anyways) and timing will be slightly retarded but thats okay for now. Well guys how much is gained from decking it 2 or 3 thousandths??

phorensic

Don't know how much compression you will gain, but it probably won't be a full 0.5. Your compression isn't THAT bad as it stands. Just need a turbo that will kick in at relatively low RPM and now you are set to run high boost. I would rather be at 8.15:1 than 9.5:1 for starting a turbo project. I've seen 7.0:1 motors before.

phorensic

BTW, you have an advantage over those tiny 1.8L and 2.0L turbo Honda and Nissan motors, so don't worry about it. Just dect the head a bit.

sonypete

Well when I go through with stage two and build a new head it will come back to the 8.15:1 compression since its a new head and not decked. I'm wanting higher compression untill I turbo my built up bottom end.

I talked to LC and they though about .25 for the first .010 and its starts being less since the head starts to dome at the top. SO maybe .20-.22 for the next .010 shaved. Anyone ever shave a 22RE head and cc it??(fingers crossed) or we all backyard mechanics around here, just kidden

kyle_22r

remember, if you deck the head by a significant amount, you should get an adjustable timing gear and degree in your cam. decking changes the distance between the cam and crank, and will affect your valve timing.

8.5:1 is more than a 20R has, and mine got along fine on the road(and it had 300,000 miles on it). just live with the 8.1 compression, and think of it as a good thing -- you'll be able to run more boost

sonypete

You def have a point there
But a decking of .020" would retard my cam about 1-2 degrees which is where I wanted to go with an adjustable gear, remeber I have a celica car and like the higher rpms . Plus this is all temporay because I was gonna go with a fully built and ported head in about 3 or 4 months when I actually throw the turbo on and boost it.

hondavxr

Actually you will not have the advantage over the little Honda and Nissan motors. The 22re heads are one of the worst flowing heads ever designed in the Toyota line up. A good Honda head, like the b16a, can out flow the 22re head two or three times in its stock form. Some of the earlier and later 22re heads were design similiar to the Hemi heads, which help the flow of the head a little bit more. I forgot the years and when. But the flow and design of the 22re head is super bad. The quench area of the head is so bad that it does not help with combustion or flow. You need a good bowl quench area for better cleaner combustion, which means more horses. But there is one good thing about 22re ,they freakin last forever. Here is a general rule of milling heads. For every .010" removed from the head or block will make you compression go up by .250 of a point. This is not a exact number but a close estimate. There are other factors involve also like the bowl shape, and size of your head. There is also other considerations like shape and compression of your pistons. Hope that helps if I didn't confuse you too much.

sonypete

Well Hondavxr your right about the quench, if your only talking about the early style heads. The later style heads actually have a decent quench area better than some 3 and 4 valve engine dues to less area taken for valve use. I would have gone this route actually but was running out of time and had to order custom pistons for my current engine. No doubt I'l be doing another later on in time and that is when I go with the later style head and block and drive back detonation with the better designed quench area. Plus I'll get forged pistons that work with the quench shape of the head. The head def. needs workin on in terms of flow but when it comes to boost thats no problem I know my fair share about 22R wasn't born yesterday

naksukow

Your throttle response will be worse but it allows you to run more boost. Don't worry about it and don't go to small on the compressor, you will just end up producing heat.

sonypete

Well you guys are forgetting this is only for stage one. Stage two of rebuild is a newly rebuilt head with all the works and since I can't have down time with my car, due to school, all the porting and O/S valves and such will be done on a a second head. That would only take a day to put on. So the first head thats on my engine now for the first stage won't be used in the second stage

I was just hoping someone would have first hand experience with how are heads are shapped what .020" and .030 shave would be in terms of cc's in the chamber. Just so I can get a good idea of how much I can shave with out going to excessive and gett too much retarding of the cam

naksukow

If your going to port and mill your head you will have to cc it to figure out the CR.

sonypete

Very tru but the only head I am porting will be the second head.

Its only the first head I am milling to get my compression back up and thats for the first stage, which also happens to be the non boosted stage.
First head is temporary and not being touched except milling it, well a cam is being thrown on for good flavor but thats it.

phorensic

I didn't mean how much the head will flow, I meant that he has at least .4L more than the Honda motors. More displacement will flow more air at lower RPMs = more air for the turbine. That's great that the Honda heads can flow 200 some odd cfm more, they only have 1.8L of displacement to begin spooling the turbo.

hondavxr

Phorensic, you are right to a certain point. More displacement will generally mean more air being pushed. You would be suprised at the flow rate of some of these new Japanese heads. The cfm's being moved out of these heads will make the domestic counterpart look like child's play. But if you don't make good use of the displacement that you have, then displacement means nothing. Think of it as 40 oz beer with a pin hole to drink out off. But now if a 24 oz can of beer with a wide mouth opening is also being pour, which will pour more liquid out? Is going to be the big 40 oz with the little opening or the little 24 with the bigger opening? Displacement is only good if it is full potential of flow, and combustion is utilized.

94x4

Why not shave the block instead, sonypete, since you're going to be swapping out the head anyway, so why do work on it ?

With the shorter connecting rods you've got the room and you can always go to a "plate" gasket of needed thickness to lower the compression for the turbo application when you get around to it, that way you'll only be putting money into what you plan on keeping and not what you're not, plus getting that extra compression you're looking for to play with that cam.

kyle_22r

because he wants the compression increase to increase driveability when it's N/A. shaving the block will increase the compression no matter what, and head shims suck in my opinion, especially with a turbo.

besides, at least around here it's $35 to have a head shaved...

94x4

Not "head shims", I meant a plate head gasket, you know, like a copper one that they run on top fuel, funny cars, dragsters and pretty much every ride that gets performance track time.

kyle_22r

i think copper gaskets on a toyota engine are a bad thing. iron block + copper gasket + aluminum head = electrolysis.

94x4

Alright then, what about a steel gasket (which I've seen used on the fully blown alcohol/alternative fuel cars), if that suits you ?

Honestly, my experience on "gasketing" extends no further than those that I've used on the little "tuner" rides that I've put together and alot of those were copper gaskets sandwiched between an iron and/or aluminum block with an aluminum head(s) on top with never any signs of "electrolysis".

sonypete

Well if I do that to the engine I can't get my compression up just by thorwing on new head. I want 8.2:1 when I boost it. If shave the block the permanet unless I take the block out = a bit of work. Stock everything with pitons is wher I want to be during boost just in my first stsage I need more pressure and the head is the easiest way without doing much work.