BT 20v piston inside 16v 4age

[ZenkiTrueno]

hello,im a bit new here...just want to ask about 1620 setup:

i have:
aftermarket crankshaft and rod with a 7rib block from bigport 4age, im planning on using 20v BT piston and with a 0.7mm metal head gasket, and a 16v head with 272 degree cam profile and 8.1 lift. and a 4Throttle and Fully programmable ECU

im asking for these setup:
1. can i use the 0.7mm metal head gasket with the head already been cut 0.5mm??

2. will the stock AE86 fuel pump manage to give enough fuel with a fuel regulator been installed already??

my mechanic said i need a more thicker metal gasket??so how about somene here... ???

[ga_goosh]

so you are going to run the 20v pistons in a 16v engine? since you have removed .5 from your head i would suggest to just get your self a set of high comp pistons and run the oem head gasket. with this set up you will have about 10.7:1 to 11.2:1 compression. that way the cam you have chosen will work. you will also want to do a bucket over shim since the cam will be pushing the limmits on the oem shims.

if you use the 20v pistons you will pretty much have to get a custom ground cam to keep the compression under control

also just so you know the piston wrist pin in the bluetops are 18mm and the wrist pin in the high comp and 20v are 20mm. if you have the smaller wrist pins you can get pistons from a bluetop from singapore i believe. they are 10:1 i cant remember the part numbers but ill keep looking

[ZenkiTrueno]

So you are saying that i cannot use the 20v piston with the cam that i already have?my conrod small end fit perfect too the 20v BT, and oem high comp piston is very difficult too get.. Bluetop piston i already have.. I am hoping i will get the best power out of my setup..
Correct me, is it high compression=High power? what if it has too much compression,whats the drawback?

[dr.occa]

you'll be fine with 20v pistons. what you want to make sure you right is the valve timing.

depending on clearance, it may well be an interference engine: valves and pistons may actually touch if improperly timed.

i ran a 1620 in my hatch which will now be prepped for my coupe.

[ZenkiTrueno]

How much power or torque do you get out of your 1620 setup? im waiting for the piston to come,then building the engine,so i hope to get the idea of what should i expect out of my setup,if it is fully tune..

[dr.occa]

How much power or torque do you get out of your 1620 setup? im waiting for the piston to come,then building the engine,so i hope to get the idea of what should i expect out of my setup,if it is fully tune..

i put 119 to the wheels w/ the 1620 running a pair of colt cam 261° cams at 8.1 lift, nst pulleys, megajolt programmable ignition, mikuni dual side draught carbs, yada yada yada...you should be able to see more details on it somewhere around here.

[ga_goosh]

dont forget occa is running silvertop pistons those have lower CR then the blacktop. the silvertop pistons are also shorter then the blacktop pistons are. the blacktop has a larger combustion chamber then the 16v so you will have higher CR then the blacktop. if you go too high on your compression you wont be able to run pump gas. it will be race fuel only.

silvertop pistons will be a better choice for a 16/20 swap

[dr.occa]

dont forget occa is running silvertop pistons those have lower CR then the blacktop. the silvertop pistons are also shorter then the blacktop pistons are. the blacktop has a larger combustion chamber then the 16v so you will have higher CR then the blacktop. if you go too high on your compression you wont be able to run pump gas. it will be race fuel only.

silvertop pistons will be a better choice for a 16/20 swap

that's right. good call sean. i forgot he was talking about bt pistons. thanks for catching that goosh.

[CBR_TOY]

this site rocks with knowledge....

[ZenkiTrueno]

oh noo. the BT pistons is on it way already..any other option if i still want to use the BT pistons, so that the car can be street driven without using race fuel?? don't want it to be a waste...

[ga_goosh]

yes you can make black top pistons work. you have to get a coustom ground cam or get a thicker head gasket. if you can find a head gasket that is 2mm thick then the BT pistons will be manageable with a blue top cam. your static compression will be 11:1 and your dynamic compression will be 9.6:1 which is manageable on a programable ecu and premium gas. if you want to use the small port cam then you will probably have to get a bit thicker head gasket. here is a link to a hks 2mm head gasket.
http://www.momentumgt.com/hks-metal-hea ... -2708.html

[nomuken]

You won't gain to much hp by just upping the compression ratio.
Example:
current setup: 120hp CR=10:1
if you up your CR to 11:1 you'll get 123hp (thats only +3hp)

Example 2:
current setup: 112hp with a CR of 9.3:1
With 10.3:1 you'll get 115hp
With 11:1 you'll get 117hp

Upping the CR won't do much if you don't change other things in an engine (cams, fueling,...)

[mooreofit]

yes but the power gain is very noticeable in the low load low rpm range as in most daily driving and less fuel consumption in result.i just increased the compression ratio from 9.5-1 to 10.5-1 balanced/printed and floated the bottom end. i big toe'd it all over town. it was an auto 4afe though. but a very noticeable difference during low load driving.

[nomuken]

Sorry, english is only my 4th language, so I have to ask. What is floating when you speak of your block?
Sure the increase is more noticeable in low rev but upping your comprssion should be combined with feeding your engine more air and fuel

[mooreofit]

not necessarily. compression has no effect on the amount of air coming in or out it only better utilizes the amount you already have and increases the cylinder pressure increasing efficiency


sorry i should have been more clear. the wristpins are floating not pressed fit.


4 languages!?!?! your a way smarter man than i.