standard compresion ratios

[irwin83r]

had a look cant find it...

just wondering if anyone can tell me the standard comp ration of the NB8A?

and or the other motors.. i guess that would help more people then too.

[Matty]

http://members.aol.com/solomiata/MX5Engine.html

The 116 HP Miata 1.6 DOHC motor from 1990-1993 ...higher compression pistons (to 9.4:1),

Miata automatic 9.0:1 with a moderate dish

Starting with the 3/95 start of the ODB-II implementation (VIN 14193) the pistons were changed with a slight dome to increase the compression ratio to an actual 9.0:1. The '94-3/95 pistons were factory rated at 9.0:1 but actually was around 8.8.

The 1999-00 Miata uses basically the same 1.8 ‘B’ as the 1994-1997 but it was again revised. The 'BP-4W' engine uses a block with higher compression pistons to 9.5:1 from 9.0:1.

For 2001 Mazda introduced another variant of the 1.8 ‘B’ with 'VVT' variable valve timing and higher compression 10:1 pistons.

[Babalouie]

I think JDM-spec NBs are a half point higher too. So I *think* that JDM NB8A is 10:1 and NB8C is 10.5:1

[irwin83r]

Cams & inner shim kit package is $1950 - delivered
Cams + inner shim kit + cam pulley package is $2250 - delivered

For near STD compression, in un-ported or machined head,
Use 272deg intake @ 10.0mm & 264deg exhaust @ 10.0mm
This will give a good gain across the rev range.
(Ideal for forced induction use also)

For 11.0:1 compression,
We recommend using 288deg intake camshaft @ 10.0mm lift,
Together with 272deg exhaust camshaft @ 10.0mm lift.
LCA set to approx 110deg
Larger gains in mid to top end power
Use large with ported head + sports injection (quads)

NB: with 10.0mm lift camshafts, please check cam lobe clearance to lifter
hole. Some Cylinder heads required modification to clear hole. (clearance
machine)
Let me know if you have any questions.
Best regards

Adrian Norton
TODA Performance Australia Pty Ltd

[kula]

ring hi octane,
ask for ian baker, tell em i sent ya.
get the tomei BP cams.

[Mason]

For near STD compression, in un-ported or machined head,
Use 272deg intake @ 10.0mm & 264deg exhaust @ 10.0mm

If you're only doing engine management and cams I wouldn't use this wild an intake cam...

I'm talking from experience, my idle had to be set at 1900 or it would stall.

[Babalouie]

For near STD compression, in un-ported or machined head,
Use 272deg intake @ 10.0mm & 264deg exhaust @ 10.0mm

Thats what Adrian told me to do...

If you're only doing engine management and cams I wouldn't use this wild an intake cam...

I'm talking from experience, my idle had to be set at 1900 or it would stall.
Ended up having to pull that cam, return it to standard and wait another 6 weeks for new cams. Cost me a lot in tuning. My mechanic was nice enough to change it over for free. At least Adrian swapped it over without charging me more...

Yeah, I was also going to say, 272s are huge for an engine with a 7000rpm redline. The Tomei 254s already make peak power at 7000rpm, so anything that much bigger is really quite wild.

[Mason]

Yeah, I was also going to say, 272s are huge for an engine with a 7000rpm redline. The Tomei 254s already make peak power at 7000rpm, so anything that much bigger is really quite wild.

I agree.

I'm running 264 on intake and I think that's why my peak power is probably around 7800 rpm. Shame the limiter kicks in before that...

[irwin83r]

thanks guys will give hi octane a buz

[Mason]

I posted some replies bagging Adrian from Toda Australia. Adrian and I have had some positive discussions. He was man enough to apologise for any miscommunication. So I've edited some of my comments.

I will say again that I think Toda Products are extremely well designed and made. I'm an Industrial Designer by training (but not currently working as one) so I understand the time and effort going into designing a product.