How do the JZ heads compare to twincam RB heads?

not sure yet

just done some lookin on the net couldnt really find much but found a statement from a SAU member that the 1JZ head flows better in stock form than the 26head not sure how true it is tho

If it is true then the 2J head would kill the 26 head.

yep what is the std valve size of the rb30 head? rb26 is 34.6mm intake and 30.15mm exhaust rb25 is 34.15mm intake and 29.65mm exhaust 2JZ is 33.6mm intake and 29mm exhaust so 1mm ovasize on a 2J will match a std 26 on the intake but be smaller by 0.15mm on the exhaust to me that is pointing towards the twincam rb heads in stock form flowing more than the JZ heads but then the port design would be different so u neva know Some original photos have not been recovered yet.

A better port design could easily make up for the slightly larger valves. If the JZ's still flow better with the smaller vavles it really says something I'm thinking of porting my RB30E head for my back up car. Its embarasing to drive with the amount of smoke it blows on start up and idle. I reckon its just the valve stem and valve guides. So I was thinking of getting a cheap rebuid and practising porting on it. Any tips for a first time RB30 head porter? Some original photos have not been recovered yet.

pigsy is the 1 to talk to about porting ill let him fill u in as i dont know anythin about it lol

yep don't touch wat u don't no about ,as u dont no wat u are doing ,u can go backwards very quick and porting with a die grinder isnot as easy as alot of people think.

Quote: yep don't touch wat u don't no about ,as u dont no wat u are doing ,u can go backwards very quick and porting with a die grinder isnot as easy as alot of people think. Thats why I am asking for advice I'm gonna do it. I always do seemingly complicated stuff with no prior knowledge. Its fun, specialy when I get good results Check out my other car. http://www.performanceforums.com/for...php?t=67194478 (http://www.performanceforums.com/forums/showthread.php?t=67194478) I was planning on mainly just smoothing the ports out without taking much material off. Where should material be removed from and where should I avoid taking material off? I know the short turn radius is almost flat so I should avoid taking anything off there? Some original photos have not been recovered yet.

getting alot better now should neally have the 220 cfm

get us some pics up troy

what diameter bore adapter are you using for the flow bench?

Quote: Originally Posted by NZ VLCT what diameter bore adapter are you using for the flow bench? 88mm the hole sleve no adapter wat size did u use for urs 4''

87, same as the bore Im using, if you go any bigger it unshrouds the valves and they flow more than reality, but 88 is good.

well it hasnt been all smooth sailing thoughwe have done quite a few different port it hasnt come up in just 1 go Quote: Originally Posted by NZ VLCT 87, same as the bore Im using, if you go any bigger it unshrouds the valves and they flow more than reality, but 88 is good. is that the hole pipe or just a reduder we have made a stand just for the rb26 rb30 /2jz

the pipe that sits under the head and simulates the bore of the motor..... I reckon u could go 235 - 240cfm with an RB30 intake port, but it would take a heap of work, lots of heads and lots of Z spar and a full custom intake manifold. would be nice tho........ or someone could make a full aftermarket head for the RB30ET, similar port layout to the Esslinger ARCA head, mmmm.......320cfm SOHC

we aint using zspar, using fibre glass resin ,got a mate with a body kit shop, so we can use the same head over and over results are geting better ,but it takes time and the bro's only spent 5-6 hrs so far on developement ,as he still has a business to run so l carn't push him to much just gota wait , give him time l just go in and get the ports close to shape around the 190 cfm and he finish's themit aint hard to get a un bogged head to flow 190--195cfm so my bro is the pro at it .

how many intake runner CC's ?

Quote: Originally Posted by NZ VLCT how many intake runner CC's ? havn't started on the manifold as yet its gona be all custom to suit gona play with that after the heads done 1 thing at a time. lve been told should be easy to get 280cc out of a runner

Quote: Originally Posted by cmy747 i just had a head done flow 211cfm at 500 collin wat brand of flow bench does jerry have as were sitting on 209@500 but were using a full 88mm bore not a reducer as they make the head read higher cos with a reducer were making alot more ,thats with only a 3-4mm raised port lookin at being realistic the high flowing ports have to be atleast 8mm but then then roof gets pretty thin and starts to get exspensive even for me were gona have l more dig today with a toatly different port see wat happens there be keen to find out on ur input