high HP Nat Asp

[irwin83r]

whats the highest HP reading anyones heard of for a mx5 1.8L naturaly asperated motor? race car and/or street.

[roddclarke]

well there is a few of us with road car around the 96rwkw..

but i think CT or one of the other race cars has the top spot of about 115 to 120rwkw.. detuning to keep in the class power to weight...

is that right CT????

[CT]

Kinda. Brians stroker had the most, aound 120rwkw I think (Brian?). Mine had almost 117rwkw but depending on fuel and dyno drops down to 110rwkw. I can only speak for myself but you are up for $7k minimum to get to this level. We (actually, my dad) handmade lifters for my engine and spent 1/2 of the money on components - the rest on the head. I had sponsors (Thanks to Martins Engine Reconditioning, Wollongong) look after much of the cost which saved my bacon. Also, that's with a stock intake and throttle body setup.

If you research the big forum, 170 rwhp or 125rwkw is a high HP NA motor that is still quite drivable. That was my target.

[irwin83r]

CT, do you have the number of the guys in wollongong that done your motor? im in the wollongong area also would love to come see your car and pick yer brain about what you done and what you'd do differently.

[yarnmx5]

I want one! CT what version of the 1.8l did you acheive such power, NA or NB. Also, at about what rpm did you get 110-117rwkw, standard fuel intake system you said?

I have a daily driver NA6A 75rwkw with a 220K Km engine that has never been touched. Its getting a bit tired and the NA8A conversion may be an option instead of refreshen (although much more expensive). If I can even get 100rwkw out of a 1.8l I would be happy. And no, I don't want forced induction.

I know of someone on this forum who could only ahceive about 85rwkw from a NA8A and it kind of put me off of the idea. It will be a big job for me as I would want it RTA approved and this means I have to temporarily remove the microtech setup I have to get it through, then put it back on.

[Sean]

It's possible, yet challenging to get a microtech passed emissions/RTA.

[yarnmx5]

I must say, I dont think I want to go through the hassles of getting it rejected...going back...trying again...etc. This is why I might just stay with the 1.6.

[CT]

OK, plugs for my engine guys:

Darren at Martins Engine Reconditioning (W'gong) for the block, crank work and the balancing.
Geoff at Wollongong Engine Reconditioning for all the head work.
Joe at Zanotto Automotive in Corrimal for screwing it together really well.

These are great guys and do excellent work. Tell them Chris sent you!

My engine was a 95 NA with 80k klms on it and running perfectly. The NB head would have made more power but I couldn't find one cheap enough.
- 2mm overbore
- 11:1 forged pistons
- forged rods
- balanced
- 11:1 comp
- 8000 rpm limit
- modified head, stock sized valves, cosworth valve springs
- solid custom made lifters
- custom made cams to suit head flow profile and cars use(Tighe)
- runs pump 98 fuel with an EMS stinger computer (el cheapo)
- stock intake manifold, TB, CAI, injectors, fuel system
- custom exhaust headers and 2.5 inch system though lukey race muffler

100rwkw is easy(!) with a BP motor. Overbore, higher comp - 10.5 minimum, ~260deg cams with good CAI and exhaust with ECU and you'll be close. Head work to clean up the chambers and valves and you'll be there. There is no magic recipe, I just followed what the guys in the USA and the guys over hear are doing. Compression is what helps these engines make power and more revs are not always your friend. Once the cams get big, 275+ degs you'll need solid lifters with under bucket shims otherwise you'll start popping the shims out - which is why I custom made the lifters in my car - much cheaper than Toda too!

[Craig]

2001 NB8B 1.8 and factory computer would be fun in an NA

[yarnmx5]

Ok, LET ME DO THE SUMS

low km NA8A - $1100 mania
shipping to me adel - $250
strip down - $200 (tools I need, engine stand)
bore work - $? not sure
11.1 forged wisecos $1000 includes shipping
forged rods $dunno
headwork clean up 3 angle etc $500
valve springs $?
custom made lifters $?
cams $1500 this is a guess
rebuild and put in car $1500
engineers report...and yes I have checked..they want one $350
remove microtech get it passed and put it back on $1000


I think I'm broke!!!!!!!

I knew I did'nt with this for a reason.

Go the 1.6

[Babalouie]

I'd echo what CT said...

Say..1.8 block, overbored to 1880cc with 10:1 NB8A pistons, cleaned up head (and milled 25 thou for more compression), 256deg cams and the usual other mods would get up to at least 95rwkw with little prob. It would look just like a stock NA8 motor with some breathing mods.

My engine is 90rwkw and is basically a stock NA8 motor with 10.5 compression, some mild cams, a simple A'pexi piggyback and the usual intake/zorst/header. No porting work, and just stock rods and crank.

I'm sure that with a smidge more capacity, and some tuning work with the cam timing (which is currently stock timing), 95rwkw would be an easy target, and it would all work with the stock lifters and 7000rpm redline.

The cheapest option for cams would be Tighe regrinds, which are about $550 delivered and will work with the NA8 hydraulic lifters. I've got Tomei billet cams which were only $750 in Japan, so it's possible that they might actually be quite affordable thru the usual JDM parts importers...bore hone was $800 and that included assembling the bottom end for me with new bearings...not sure how much extra a slight overbore would be but potentially it might not be much. The most expensive part was the head reco which was $900, and that was just a stock rebuild with a 25thou shave.

[CT]

Ok, LET ME DO THE SUMS

low km NA8A - $1100 mania
shipping to me adel - $250
strip down - $200 (tools I need, engine stand)
bore work - $? not sure $600 incl balance
11.1 forged wisecos $1000 includes shipping
forged rods $dunno $900 from USA
headwork clean up 3 angle etc $500 (Try $1000 minimum)
valve springs $? $500 from USA incl tit retainers
custom made lifters $? (not necessary unless 11mm lift)
cams $1500 this is a guess ($600 delivered from QLD)
rebuild and put in car $1500 (hope not!, maybe $500)
engineers report...and yes I have checked..they want one $350
remove microtech get it passed and put it back on $1000

Plus, Toda head gasket $450 and mazda gasket kit and water and oil pumps $900 and adjustable cam gears $400 from USA. Add mazdaspeed engine mounts $90 and a big PWR radiator $770.

Who said motorsport was expensive

[93_Clubman]

or for around $3k do what roddclarke indicated he & a few others have done to get around the 96rwkw mark.

in my case started with a standard '93 na8 clubman: 74rwkw on dyno dynamics @ autotech cbr

+ simota air filter: $30

+ mania cai pipe: $120

+ stewart performance hiflow cat & catback: $950

+ 32 bit unichip fitted & dyno tuned: $1300

= 94rwkw on same dyno

for a little more power fit headers (stewart performance $600), use your microtech & its built in MAP sensor to replace the MAS, & replace the na8 intake pipe with a hiflow type. depending on the tuner & the dyno you should have close to 100rwkw. & if you want even more power, you can still do the engine work when funds become available again...

[CT]

93_Clubman - I am superbly impressed that you got 20rwkw without headwork and/or cams. That is the first time I have heard of such gains on an early 1.8 BP. The NB8B engines gain about 10 rwkw with the same mods that you have mentioned and they are a higher compression engine and have VVT. Something is not quite right. My previous race engine had modified head, cams, intake, exhaust and fully programmable ECU (not a piggyback) and it went from 75 to 87 rwkw. Are you sure you're not telling us something?

[yarnmx5]

for the same mods on my NA6A, I went from 62rwkw to 75 rwkw. I have all the loch goodies and the microtech.

Just out of interest, if i went to the 1.8..beside having to change the headers, could i keep the rest of the loch system, ie cat back and intake.

Anyone want to sell a 1.8 engine with all the goodies done