Difference between 250BHP and 280BHP??

[AL3X]

What actually is the difference between the 92 RX7 approx 250BHP and the later models 280BHP?? Is it just a different ECU or chip or something like that?? If it is, is it easy to convert the older models so they also have the higher BHP??

Also is there a great difference in performance between them??

[maximtaylor]

The earlier cars at 255 bhp used an 8 bit ecu and ran a boost pattern of around 10 - 8 -10 psi.

Sometime in 1996 the ecu changed to a 16 bit unit and I believe that the boost may have been increased a smidgen to get to 265bhp.

Some of the very late rx-7\'s including the RS model reached 280 bhp and had slightly upgraded turbos. Same size as before, but with tighter tolerences to achieve better efficiency. Also ran slightly higher boost again.

In truth, whether you have a 92 car or a 99 car, by the time you put in an aftermarket ECU they will be fairly equal. Any RX7 is quick, tuned or not!

Regards

Max

[Fish]

I think they also changed the blades on the turbos to flow more air, thus allowing the higher BHP figure.

Dan

[AL3X]

So its not as simple as just getting it chipped then!? Has anyone here raced a 92 against a 98 to see if there is much init??

[Fish]

Putting an import against another import there wont be much difference. Put it up against a UK/Euro model and the import will wipe the floor with it.

But back to the question you asked. To get your 255 up to around 280, you need to look at two main areas. ECU and fuelling.

ECU would best be resolved by fitting something like the Apexi PFC. This controls both fuelling and ignition, and is mapped to YOUR car.

Fuelling would best be checked on a set of rollers. They just need to check for running lean at the top end. If it is, then get yourself an uprated pump and fuel pressure regulator.

Dan

[AL3X]

Im new to this so i appologise if this is a stupid question but is the Apexi PFC atually a new ECU or is it a bolt on to the existing one?

[richrx]

the apexi is a new ecu, they do cost alot although people who have them will tell you there worth it:D

after you get one you could get a full decat exhaust and get arount 300bhp if done properly:D:D

[AL3X]

300bhp those magic words! 300 and BHP in the same sentence!! It already has a cat back zorst on it, so just would need to get the front sections. So how much would i be looking at for an Apexi ECU? Mine is an Auto so would that make a difference?

[kevint]

You can get a Power FC for c.£665 e.g. //www.sensetuning.co.uk  There is a guy in the UK running with an auto with no problems but I don\'\'t know whether Apexi officially recommend it with an auto.  The FC Commander is also a good add on to the ECU, it allows you to monitor many of the sensors i.e. boost, intake temp, injector duty.  The Commander also allows changes to the map, but that is best left to an expert.  The commander is £215 or so.

Kevin

(edited to correct URL&Prices)

[AL3X]

So the commander is an add on rather than an ECU change?? Will this also allow BHP increase through the re-mapping capabilities of the commander??

[maximtaylor]

Nope!

The Apexi Power FC is a complete replacement ECU, fixes onto existing harness - 5 minute job Take out old ECU, put in Power FC.

The Commander unit plugs into the above - 30 second job

Regards

Max

[bnaellis]

Difference between 255bhp & 280 bhp is the exhaust has 10% less back pressure the turbos as explained earlier also they are actually smaller than 92-98 models slight increase in boost and because of the size of teh front air dam the air flow to induction and intercooler is better these are what consist of the extra power. I believe the 10% less back pressure in the exhaust is only  in the back boc the rest of the exhaust system I believe is the same. I also run a apexi on my auto with base map I would not really recommend it but I do it anyhow car runs rough intermittently I think because the stock ecu retards the timing on the auto when in de-acceleration but the apexi as far as I know does not do this so I think thats why mine cuts out every now and then. I will find out when I get round to having it mapped properly.

rgds