Mazda Rotary Club

Cars by Model Type => 3rd generation RX-7's => Topic started by: Bobbit on June 24, 2009, 10:19:03 AM

Title: Porting on twins?
Post by: Bobbit on June 24, 2009, 10:19:03 AM
Hi guys,
Just wondering if there is much point in getting an engine ported if you\'re still running seq twins?
Title: Porting on twins?
Post by: leon on June 24, 2009, 11:11:21 AM
Why yes there is, you can make more power and i belive it will spool a tiny bit quicker?. it\'s also future proofing as you would want to port your engine if you ever went single and if your engine is out it would be a shame not to do it at the same time :mmmm
Title: Porting on twins?
Post by: Bobbit on June 24, 2009, 11:22:52 AM
Cheers leon, i thought as much but my brain was doubting itself.
Title: Porting on twins?
Post by: rx7boy on June 24, 2009, 12:00:03 PM
Yep sure will, I have an aggressive street port and my twins are running non sequential and lovely smooth power all the way !! plus if you do it now you wont when u switch to single !
Title: Porting on twins?
Post by: Aceman on June 24, 2009, 12:56:28 PM
Same here - agressive street port, exhaust port etc..

Makes a very nice car to drive!! :)
Title: Porting on twins?
Post by: chrisJDM on June 24, 2009, 01:34:25 PM
yes its a great idea to get porting on twins will make a bit more power, just dont go too big on the ports as you may get boost creep
Title: Porting on twins?
Post by: HaywardRotary on June 24, 2009, 01:53:56 PM
you wont get boost creep from porting,maybe other things but not porting.
Regards
Carl
Title: Porting on twins?
Post by: Ada7 on June 24, 2009, 02:13:21 PM
Whats boost creep?

Adam
Title: Porting on twins?
Post by: Kevin on June 24, 2009, 02:30:51 PM
Extra unwanted boost spikes, normally as a result of making things more free flowing.  For example the addition of a downpipe with no adequate boost control support.
Title: Porting on twins?
Post by: Grizzly on June 27, 2009, 05:43:39 PM
Actually, do i have this the correct way round??? Creep is when you are in 4th gear at wot so there is quite allot of load on the motor, the boost will slowly rise over the target boost setting and not drop back until you let off?

Spike is where your in a low gear say first and you floor it, the boost rises quickly and overshoots the target level then starts to drop back.  

Does this sound correct or have i got it mixed up?
Title: Porting on twins?
Post by: skybusr34 on June 27, 2009, 05:59:13 PM
sounds bang on to me Grizzly
Title: Porting on twins?
Post by: ryan_v on June 27, 2009, 07:44:01 PM
i concour grizzly lol
Title: Porting on twins?
Post by: Nik da Greek on June 27, 2009, 08:51:30 PM
Yeah, you\'re right, Grizzly. Creep is usually caused by crap wastegate design not being able to shift the gas quickly enough so it continues to load up the system with loads of extra pressure quicker than it can get rid of it, and the worse it gets the more it happens . Spikes happen when the system\'s a lot more free flowing than the boost control loop can cope with, so it can\'t reign boost in quickly enough and overboosts.

....that was a really terrible attempt at explaining it, hope it makes more sense to you guys than it did to me reading it back :3Confused
Title: Porting on twins?
Post by: yappa on July 07, 2009, 12:06:27 AM
how much does porting roughly cost?
Title: Porting on twins?
Post by: L18M on July 07, 2009, 12:16:33 AM
around £350-£500 maybe more depending who does it and what kinda of ports..
but if u port u cant just port on its own.. as block needs to come out, seals would have to be replaced etc...
Title: Porting on twins?
Post by: Mike_rex on July 08, 2009, 05:15:48 PM
where can you buy the templates and whats the best port for a engine running non sequential twins but hopping to go single in the near future
Title: Porting on twins?
Post by: ghostjd on July 08, 2009, 05:51:30 PM
Racing beat and pineapple racing both do them, I\'m sure there\'s local suppliers too, try MRC, Hurley and Rotary Art, I\'m sure there\'s others.
Title: Porting on twins?
Post by: kiwiracer on July 08, 2009, 11:49:01 PM
Quote from: L18M;623704around £350-£500 maybe more depending who does it and what kinda of ports..

and what quality you get for your money fella,some bad porting out there :spank,seen some pics on other forums