Another build thread

[CTWV50]

Originally Posted by skov

I'm confused too - I thought the B6GP was the ECU for the 90bhp version

Is there any chance you could pop the lid off your ECU and take a photo of it's innards?

Yeah sure, do it tonight. It's definitely not the 90bhp engine or the engine code would start BP and I did sort out the loom using the B6 wiring diagrams. I think this is a case of incorrect internet forum posts. I thought my car was BP when I bought it because it was a '95 car so probably other people have too and assumed the B6GP was for the later 90bhp engine.

[CTWV50]

HA! There you go!

https://www.mx5oc.co.uk/forum/yaf_po...questions.aspx

[CTWV50]

OK I'm doubting myself now!

edit: This is what I typed 3 years ago on my build thread...

Originally Posted by CTWV50

Yeah FWD VWs and audis, I've had a fair few, not great at getting off the line and not as reliable as people would have you think. Anyway back to the MX5, I can't believe they fitted an aluminium sump and a stainless steel exhaust manifold as standard, such a bonus, engine should be nice and lightweight, bye bye production car understeer!

I'm reading a book about the design/development of the MX5, weight was a massive deal, people were threatened if weight wasn't kept to a minimum. They even lightened the crank and flywheel compared to the 323 transverse engine it was based on allowing to rev to 7200rpm.

The Donor is a 1.6 1995 model but it isn't the later tweaked 90 bhp engine that was not available to buy till Nov 1995 and had a steel sump. Mines a May 1995 and has a B6 engine code. So if anyones looking to buy a 1995 mx5 check the engine code is the correct for the one your after and seeing as the emission test was tightened up for cars after August 1995 you may want to play safe with the earlier engine. The 90bhp engine code starts with BP. Had another nose under the engine bay today just before dark, the rad fan is only half the size of the radiator and looks like it will be suitable for the roadster if it can be made to attach to the polo radiator.

Signed up to mx5oc forum to get a seller thread going when I'm ready to break the car down.

Need to get the garage sorted first and get some welding practice in before building the build table. Took some measurement and if I keep the garage clear I should be able to keep the whole car in the garage when finished along with other essential garage belongings. I may need to sort a shed at some point though for the gardening tools. I digress...

That is all goodnight.

[skov]

Originally Posted by CTWV50

Yeah sure, do it tonight. It's definitely not the 90bhp engine or the engine code would start BP and I did sort out the loom using the B6 wiring diagrams. I think this is a case of incorrect internet forum posts. I thought my car was BP when I bought it because it was a '95 car so probably other people have too and assumed the B6GP was for the later 90bhp engine.

Ummm, I thought only the 1.8's were BP engines, and the 1.6 was a B6 regardless of whether it was a 115 or 90bhp unit

[CTWV50]

Originally Posted by skov

Ummm, I thought only the 1.8's were BP engines, and the 1.6 was a B6 regardless of whether it was a 115 or 90bhp unit

You know what! I think your right it's a 90bhp! I'll check the wiring diagrams I used for injector outputs but I have a feeling it's sequential! Good job I've got that 1.8 engine sat there!

[CTWV50]

It's a 90bhp. I believe you can turn it into a 115bhp as you say by batching the injectors but needs cam change to make it work correctly I think although my engine is 9:1 not 9.5:1 like the earlier engines. Hmmm!

[skov]

As far as know you need to change the cams, pistons, and ECU to convert it to 115bhp spec.
A heavy head skim might have the same affect as changing to the higher compression pistons.

I do belive the 90bhp version is the engine of choice for turbo applications though

[CTWV50]

Originally Posted by skov

As far as know you need to change the cams, pistons, and ECU to convert it to 115bhp spec.
A heavy head skim might have the same affect as changing to the higher compression pistons.

I do belive the 90bhp version is the engine of choice for turbo applications though

Oh really!

[PorkChop]

The 115bhp 1.6 was dropped by 1994 when Mazda introduced the 1.8 BP engine. AFAIK only the European market had a 1.6 offering (the 88/90bhp) from 1994 on. The BP engines are all 1.8, all the 1.6 Mazda B engines have the code B6.

It's lower CR will lend itself to charging, however, I believe things like the piston squirters were removed when the 90bhp unit was introduced, which makes them less suitable. The majority of charged 1.6s I know of are 90-93 based.

[skov]

That's my weekend sorted!