lazzer408

iTrader: (1)

Who here has alot of experience with 1.8 internals? I have a few more questions like...

What's the spring pressure of stock valve springs?
How big a spring can the stock valves handle?

We need a sticky of the Miata's mechanical limitations such as. "Valve float at xxxx rpm" or "Stock pistons good for xxx hp" and "Stock valves up to xx lb springs".

Anyone have a going list?

Monday my block and crank go to the shop to get prep'd. =) I need to get started on the head but I'm not quite sure about what valve/spring combination to go with. I just don't want to float a valve -when- the trans blows.

EDIT - What HP/boost can the stock head/valve train handle?

cardriverx

iTrader: (12)

well roughly, valve float is at like 7500 - 7750 rpm. Stock pistons have seen 300+ horsepower, and some people have made even more power without touching the heads.

Braineack

iTrader: (62)

FM is the only place that can rebuild an engine and keep the tolerances correct.


bye bye built engine. I doubt it will last 5K.

90turboMX5

I disagree. Stewart Engines here in Indianapolis is an excellent engine builder. Jim Steward, the owner has A LOT of experience on Miata engines, they do hundreds of spec Miata engines each year. He knows everything about Miata engines and he will answer your questions if you call him.
317-244-9129
www.stewartracingengines.com

lazzer408

iTrader: (1)

Now why would you say that? You'll jinx it.

There are two engine builders here doing imports and I haven't heard any horror stories...yet. I know they dod some high HP Mitsubishi builds but not many Mazdas.

Thanks 90turboMX5 I'll throw him a call and see what he recomends.

Dhaark

iTrader: (3)

You could always give The Parts Group a call. he coul dhelp you somewhat... an proably has teh answer about the stock head.

Braineack

iTrader: (62)

Just so you know, alot of machine shops do not / cannot get the tolerances that newer motors require, that is why alot of "built" Japanese motors blow up within short time. Manufacturers put alot of R&D into their engines and have very very tight tolerances. Unlike older small and big block motors that can get away with less strict machining. All I am saying is that you should really know what your getting yourself into and have someone reputable who is going to put your motor together and make sure that all your tolerances are right within spec from the machine shop. I am saying this because a friend of mine just had a b18c1 built from a "very reputable machine shop" and luckily being as ---- as he is, while he was assembling the motor he found that the machine shop machined his crank to achieve bearing clearances which they were not supposed to do. Then he had to battle with the machine shop to have them replace the crank. Now this causes even more down time in the project as well as more head aches. It is a very long process and there is always surprises and stuff you do not account for. If you want a motor built you should go through Flyin Miata. Seriously, even though its expensive, they are a company that definately knows / understands a Miata's internals and have proven their worth time and time again. Atleast you can have the ease of knowing that your going to receive a motor that is going to work the way it should. Lastly, have you ever driven a Miata making around 200whp? Let alone more which is where a built motor would be capable of. The more power a miata makes, the farther away from being that fun, tossible, easy car to drive it becomes. Just my .02 but to each his own, good luck with whatever you decide to do.


Talk about the "Anti-DIY crew". Just because you all have a ton of money to throw @ flyin miata doesn't mean its the "best" solution. Rockdoc could easily get away with 800-900 dollars in "base" parts (pistons,rods,studs,gasket) for the bottom end. If he so chooses, he can then refresh the head and build a nasty head later. Miata motors are not lambo motors or something that is so technically advanced that only one shop can machine them and build them. They were made in the late 80s....

Roc, there is more then a few people who have done what you are intending to do, with costs on miataturbo.net. I would search through there. I think with machine work my total build was like 2k.

^^^I totally agree, but having tolerances in spec, proper machining, and assembly is the difference of a built motor lasting 5k and a built motor lasting 50k.


see....it's written in stone.

http://www.clubroadster.net/forum/vi...asc&highlight=

akaryrye

iTrader: (5)

I rebuilt my motor myself and so far it is still running. I was careful to check the bearing clearances to make sure they were correct, I checked the bore diameters with a micrometer, cleaned and lapped all the valves in, and threw on some carillo rods. The only thing that worries me about my build is that I didnt do any balancing, but I hope with a stock crank, high quality light weight rods, and the stock pistons in the same bore they were pulled from was enough. So far, runs smooth after 2k miles or so and compression is like 180 per cylinder with the motor cool.

MX5-4me

When I was having a difficult time finding a machine shop to build the engine in my old car, I couldn't find a local shop (at the Time) that had their equipment calibrated on a regular basis, I ended up going with an airplane engine machine shop. They are required by the FAA to have their tools calibrated on a regular basis.

You might also want to check with local sport bike guys and find out where they have their engines built.

Either way good luck. doing engine builds kick ***.

What block are you starting with?

MX5-4me

Did you you have the cylinder walls honed before you put the new pistons and rings in?

Loki047

iTrader: (6)

Lazzer whos doing the build and how much $$?

I need to get mine done soon

Marty

Stop drinking the Cardell Kool-Aid

TurboTim

iTrader: (9)

First off, braineak is just busting our *****.

I have been working with Jim on a few Honda things and have found him to be knowledgeable and easy to talk to. I actually have to call him today. I found out he did spec miata engines recently and I got the impression he just recently started building them for AIM who's right across the street. I may be way off here cause it was a little while ago. I know if I had any questions with a miata build he'd be the first guy I'd call, then maybe Bill from FM.

myhotrs4

Go with Stewart , I have only heard good Things!!

Braineack

iTrader: (62)

Es joke.

http://www.clubroadster.net/forum/vi...asc&highlight=

Was just posting here....

Markp

I found several excellent machine shops, if you go to the trouble to tell the people what you need for clearances usually they will do just that. I go in with specs and tell them I plan to mic all the parts after. Usually that's enough motivation for a good shop to give you good results because they don't want to redo it.

It can handle quite a bit. I am running ~65 lbs closed and ~170-180 open with dual springs. stock valves aftermarket retainers. The dual springs that Belfab sell should be fine.

According to R&D Valves, in Hesperia CA. About 10 PSI. He's conservative. In reality, you lose some power over 10 PSI from the valves not properly closing... don't know how much. HP is irrelevant! RPM, about 7500.

Mark

MX5-4me

That's interesting. How does boost effect valve function?

y8s

iTrader: (8)

the same way opening suicide doors on the freeway does.

y8s

iTrader: (8)

oh and hey mark, since you have probably the most miata engine building experience within 500 miles of us DC metro guys, I want to eventually pick your brain on building my motor.

MX5-4me

So the pressure holds the intake valve open?

Ok next question can you used stiffer Valve springs without using Ti Retainers?