Mazda Rotary Club

Cars by Model Type => 3rd generation RX-7's => Topic started by: hy_seew luing7 on December 04, 2003, 07:28:12 PM

Title: Rebuilt Engine
Post by: hy_seew luing7 on December 04, 2003, 07:28:12 PM
Hey, is it possible that u can rebuild ur engine so it has a bigger cc and can be more capable of higher power? thanks

Honum
Title: Rebuilt Engine
Post by: Glenn Butcher on December 04, 2003, 07:42:19 PM
Hi Honum,

No - you can\'t increase capacity with a rotary like you can with a piston engine.

The main way to achieve more power with a rotary is to have it "Ported"  for better flow of fuel and air etc..  But you can also achieve more power with exhausts/turbo\'s/ECU\'s etc..

Porting can considerably increase the power - in some cases up to double that of a standard ported engine (even without a turbo).
Title: Rebuilt Engine
Post by: hy_seew luing7 on December 04, 2003, 08:39:15 PM
thanks!! Honum :rollin
Title: Rebuilt Engine
Post by: ScuttleRX on December 04, 2003, 09:20:47 PM
QuotePorting can considerably increase the power - in some cases up to double that of a standard ported engine (even without a turbo).

Didnt realise there was so much power to be had with porting, are there any downsides to it?

suppose its also an \'insurance friendly\' mod, as would be pretty hard to determine whether it had been done
Title: Rebuilt Engine
Post by: iaint on December 05, 2003, 01:26:48 PM
QuoteOriginally posted by ScuttleRX
Didnt realise there was so much power to be had with porting, are there any downsides to it?

suppose its also an \'insurance friendly\' mod, as would be pretty hard to determine whether it had been done

Depending on the size of port done the running of the engine at lower RPM is rougher and fuel economy is fragged!

Larger \'bridge\' ports are really only suitable for a car that\'s going to spend most of it\'s time tracking or dragging.  For a day-to-day application there is a \'street\' port that extends the ports slightly.

I\'m having a street-port, de-cat and ECU upgrade done to mine at the mo so I\'ll hopefully get some figures for the power-gain from this in early spring (after the run-in period).

Iain
Title: Rebuilt Engine
Post by: johnf on December 05, 2003, 02:44:39 PM
My car had some level or porting done before I bought it and yes I can confirm it\'s quite rough on tick over and my mpg is around 14.

Not had and tests done to see what difference this has made to perfromance etc. perhaps i should - just out of interest.


John
Title: Rebuilt Engine
Post by: StreetPizza on December 05, 2003, 03:12:32 PM
How tough is it to get a car with a ported engine through the MOT? I can\'t imagine the rotary has an easy time with emissions in standard form.

Obviously the smaller the port job the easier it is, but didn\'t someone on here have a bridgeported motor on the streets? I thought that was impossible.

...or is it one of those cases where it helps to know your local MOT tester, chuck a few quid his way, that sorta thing? ;)
Title: Rebuilt Engine
Post by: iaint on December 05, 2003, 09:45:23 PM
QuoteOriginally posted by StreetPizza
How tough is it to get a car with a ported engine through the MOT? I can\'t imagine the rotary has an easy time with emissions in standard form.

Obviously the smaller the port job the easier it is, but didn\'t someone on here have a bridgeported motor on the streets? I thought that was impossible.

...or is it one of those cases where it helps to know your local MOT tester, chuck a few quid his way, that sorta thing? ;)

Depends on a number of things - like if the tester knows which test he should be applying, what year your car is and if they\'re roatary \'friendly\'.

Obviously if you know the tester and he\'ll pass you on emissions even if they\'re a fail then that\'s good for you!

Iain
Title: Rebuilt Engine
Post by: ScuttleRX on December 23, 2003, 06:23:55 PM
How much does it cost roughly to get an engine ported, presume its up there with rebuild prices for all the work involved?
Title: Rebuilt Engine
Post by: bnaellis on December 23, 2003, 07:32:41 PM
Depends on the year of car. If pre Aug 95 it does not have a cat test so co% is allowed to read upto 3.5%
The bridgeport I currently have does not have a cat and co% is currently 2.8% as it\'s detuned.

rgds