Did compression test: Turbo this engine as it sits?
 

I ran a dry compression test on my 150k '94 engine and got 170, 170, 180, 170. I picked this engine up last August after spinning rod bearings on my last one. I just grabbed the first I could find to get the car running again.

Now I'm trying to decide whether to turbo it as it sits or upgrade to a fresher, newer VVT motor first?

Seems like the numbers are pretty good, but y'all are the experts. Thanks.

Also: engine was tested cold, I've been researching this on here and I should have tested it hot. I assume hot would just improve my results though? Or do I need to go back and do it again

It would change the results, although as is I'd definitely turbo it. You're not really looking at the numbers so much as the consistency between them. You're within 6%, and that's plenty good.

Read a proper write up on how to compression test, they can tell you a lot. Everything from his many cranks (5 is the norm I believe), to the difference between crank 1 and 5, it's all telling you something.

Thanks! I appreciate the sanity check.

I was figuring with the age and mileage I'd definitely be looking at putting in another one, but with that response in mind, I think I'll just pull it to do some refreshing (clutch for the turbo, RMS, VC gasket, WP, timing belt, coolant reroute).

I'll also look up more info on compression testing, thanks for the tip.

you could do it either way bro, if it were me i would sell the engine you have, only reason I say that is because the VVT engine is a little more robust, also it will be newer, more than likely it will have better comp numbers, and you'll have a little more headroom to grow power wise. unless you dont want to deal with the complexity of the VVT engine, but either way you'll be happy with it, your car your decision.

The VVT motor will blow up at the same power levels as the 94.

Naw, it's relative, both engines, power wise are the same, although when not taking all factors of both engines into account you get the answer you gave me,,,
the difference will be in the newer engines as i said will more than likely have better comp numbers, equaling more power. plus the VVT motor has the crank location plate, which keeps it more lacated when changing load or RPM rapidly. So if he can offset the cost, for a VVT engine, that's newer hopefully better comp numbers, and is a little more robust than the engine he has, that equals more power, will last longer assuming it will be taken care of. Go Vtt, you'll be glad you did.

between the 94, and the introduction of the 01 VVT engine, thats an engine that's 7 years newer, try and find one with documented miles if possible, under 80k would be a great find, but as low of mileage that you can find and afford will do you good.

I like VVT motors, but you're really just making posts for the sake of making posts with no real meat to them.

No meat? he's asking what motor he should go with, I simply gave my opinion, that's hat he's here for other peoples' opinions, it's ultimately his decision, do a dry comp test, do a true leak down test, and if the 94 is in good shape, then he can use that one

plus the VVT has a bump in compression ratio, he can make the same power with it, with less boost on that 94.

So? Who cares?


The higher compression is a DOWNSIDE of the VVT motor, and not because it makes the motor weaker.

here's some meat, 94 cam lift intake 0.318 exhaust 0.338
01+ VVT engine cam lift intake 0.370 exhaust 0.350

VVT flows more air, with addtion of a little higher compression ration, and being newer with less mileage, VVT engine doesn't require as much boost pressure to make power.

The VVT is more robust, just an educated answer.

You need to define robust, as both motors will blow up at the same power levels.


Less boost pressure to make power is ricer BS. It doesn't matter, and nobody on here will care.

I am not trying to argue, I simply said what I thought, what's wrong with making the same power at 9psi on a VVT, than a 94 engine at 10-12 psi?

unless your wanting to run 11+ psi. the lower cmpression would be better, so you would be able to say yea i run 12 pis, as long as your making the power you want, an it's set up right. I also said he could do it either way, are you trying to make a point here? I have 15+ years experience with miatas, i don't know everything, but i do know what is fact. if i didn't know i wouldnt comment,

What the fuck does PSI have to do with anything? Repeat after me: "PSI doesn't mean anything."

What you just said is that if you want to run 10.99psi, the VVT motor is better. 11.00psi, the 94 is better.

I mean, do you realize just how retarded that is?


This is what i'm talking about. You're making posts that don't mean anything, have no meat, no real information, and is just a bunch of vague BS. It's great that you have 15 years of experience with Miatas. I have.... 3? Why aren't you teaching me awesome shit?

I don't know, why dont you make a sandwich and think about it.
He asked about a 1994 engine and a VVT. these are answers to his post, you must be bored, MY OPINION was i would go VVT. he has a 94. he hasn't yet completely inspected his engine fully.
what if someone wants to run 10.99 psi,? I feel like I'm responding to a teenager that thinks he knows everything. what are you trying to say there brother?

I'm trying to say that if you had just left it as "VVT is more gooder," i probably would have left you alone. Pretty much everything else you said is either irrelevant or ricer talk.

He ran a compression test. Motor is fine. If he wants to swap out a perfectly good motor before boosting, all power to him. I wouldn't bother, i'd boost this one until it blows, then build a VVT or BP4W at that point.


But at what PSI do you think this motor would blow? You said it's the best choice for 11psi or more. How much is too much PSI?

you'd make good power on a VVT at 9psig. ricer talk? also iwas taking other things into consideration like if he uses the VVT engine, get a standalone and learn how to use it, i don't know it it was read wrong, i simply said....

VVT needs less pressure than a 94 and will make the same power, it's newer. and probably in better shape if he looks for a low mileage example.

saying something is more gooder is something a clueless amateur would say.
I apologize i didn't say 'more gooder'.

it's not about psi if it will blow, it's how well the tuning process has been implemented.

although there is still a power limit, on point tuning will save an engine on the threshold of that (power limit).

Who gives a fuck if it "needs less pressure?" Pressure doesn't mean anything! Holy hell.

And why does he need a standalone with the VVT motor and not anything else he would boost?

If it's not about psi, then why are you flapping your mouth hole about it?


Edit Button: Do you use it?



Sure is Miata.net and/or Florida in here. Which of the 4 Miatas are you going to post for sale today?

Whoa, I didn't mean for this to get all inflammatory. Thank you for the input guys. Derak, I agree that the VVT motor would be preferable, although some of your specific points seem debatable.

However, as Ben pointed out, even though a new motor would certainly be nice, I started the thread to see if I can keep my motor as it sits. That's a whole lot cheaper than the time and money to upgrade.

Thanks guys, I think I'll just turbo this one. It'll probably fail sooner than a newer lower-miles engine, but if it does I can do the swap at that point.

Its not inflamatory. The silly n00b just wants to bump his post count by posting some borderline ignorant info.

If it helps at all, jmuse on here boosted his BP4W with like... 250k miles on it. The Begi tubular manifold is the only thing to have failed so far (SURPRISE!). Motor seems strong.

And no, it's not an inflammatory subject, i'm just white knighting on your behalf in an attempt to keep the dumb away from you. :rofl:

Wait, huh... Why?

Or do you mean how the higher compression is acheived?

Moar compression = less timing = failsauce.

OMG, shhhhhhhhhhhhhut up.

How in the world a $1200 engine with "documented miles" in a $3000 car that currently has 170/170/170/180 compression numbers better? That's just nonsense.

Doesn't matter, gained post count.

No, I merged his posts down to 12. It'll buy is 10 minutes of PM quietness.

lol @ psi talk. You picking out his turbo for him too breh? I agree with concealer. Run it till it busts.

I'm not sure why your last one went, your experience with tuning, or your plans but those compression numbers look pretty good to me. Anything that is within 10% across the board above 150 is pretty good IMO.

If you have everything running correctly and aren't stupid that motor will last for a good while.

If you want to switch to vvt they spool quicker. BUT you probably won't be running any big turbo anyway since stock block. Your spool should be quick anyway.

If you ever plan on going built motor you could just buy a vvt motor (in decent shape who cares about miles) drive around on that while you build your 94 bottom end and then plop the vvt on the 94 and be on your way.

That's my opinion.

Last one went (naturally aspirated) because I had an old, clogged radiator and didn't watch my temps at track day because I was busy giggling like a little school girl.

Definitely not the car's fault.

Yeah, that's true, although if I were looking to build it I'd probably just get another old engine to build. For the time being, I'm just eyeing like high 100's whp to start, stock injectors, and then try to go to low 200's, that's about it.

You won't hit high 100s with stock injectors.

RX8 injectors are a superior design and only $28 each at Rockauto. They're 420, and good for 200-215 flywheel hp. That's at 80% DC, so plenty of headroom.

BTW I think this post is on the money. You're well within your means on your power goals. Stock injectors will be pushing it though.

edit: curly beat me to it on the injectors.

The RX8s will do more than that quite easily. The 95 is running pretty rich up top still and is taking 12psi to hit 84% DC. Made 220whp on 10psi. I could easily lean it out enough to keep it under 80% on 12-14psi on this car. (BUT PSI MEANS NOTHING!!!!)

That's very good to know. My approach is really to just do what I can probably with the FM voodoo II kit to save time and get some more power, and I was going based on their reported numbers.

I'm basically planning to pull the engine, refresh gaskets and seals, put in a new clutch while I'm there, coolant reroute, slap on a Voodoo II, shove it in, and see how it goes. Edit: and I forgot to add, getting a WBO2 as well of course.

I think any significant increase over stock is plenty for my skill level on the track for the time being.

Then later on, I figure I can ditch the piggyback for a megasquirt and look seriously at my injector options, and do the best radiator/fan upgrade I can get.

Do it once, do it right.

only for pump gas peasants

Well, googling the voodoo box again in response did get me thinking... The appeal here is having FM hold my hand without paying for a hydra.

If they're really that dangerous, I suppose I could go straight to a megasquirt, I just have no idea what I'm doing.

If you only ever want high 100s whp, do the voodoo now. If you even think you might want more power in the future, do the megasquirt first. Learn to tune it now, before adding a turbo.

If i'm going to use E85, i ain't fucking around with a limpdick 10:1 motor, either.

That... is actually a really good idea. I'll have to go read more. One thing I have searched for and not gotten a good answer on is whether I should spring for an MS3?

I know with a VVT motor it eliminates the need for VVTuner, but for my '94 motor that isn't a concern of course. Does the increase in table size and resolution make a big enough difference to warrant the extra $$?

MS3 gives me prostate exams. In the right way.

as in stock rods?
or as in you'd go higher comp?

doesn't matter, I don't care.

lol

*edit: its a great dual purpose compression ratio IMO. run corn when you have it, back off slightly and run pump when you don't have corn. Going higher would make pump map difficult.

All of the above.

Depends on what you you want. There are entire threads that discuss this. My ms1 worked just fine. My a/c functions a lot better on ms3 and now I have sequential fuel and spark. Also there is actual documentation on ms3 so It's easier for me to follow tutorials. MS1 menu options aren't even close to ms2 or 3 so it's hard to follow other peoples howto info.

There are a lot of other reasons to switch like more inputs. I read a lot of stuff saying how much better peoples cars ran after switching to ms3 but mine wasn't really noticeable other than a/c. I was only running 265cc injectors though. My car idled very smoothly before and still does (I'm running 1000cc id's though now).

Based on you asking questions though I'd recommend buying an ecu built by a forum member like brain or rev though. They'll support what they built and the extra money will be worth it. As concealer said do it once and do it right. There is a difference between being a cheapskate and thrifty. If you're cutting corners to barely make it you should probably re-evaluate what you're doing.

Why dont you call the owner of flyin miata and ask him if I'm a Noob....

I don't need to. I have first hand experience, not just regurgitating information I heard from someone else.

I don't think Bill would bother giving anyone the time of day if we called up asking stupid shit like that.

The times i've met him (in person HAHAHAHA I CAN NAME DROP TOO!!!) he seemed like a really nice guy who just didn't give a fuck.

I fail at search then, because I swear I did look. :dunno: Thanks for the excellent information. It does sound much easier to set up - for somebody with no experience like me, that's a huge plus and worth the price of admission right there.

Thanks for the info, I think you're right - I'll try getting a rev-built MS3 in there NA, and then proceed with the FM no-electronics kit after I have it running.

I assume the fresh radiator that kept the car at 200F all day on the track would probably still be sufficient with a turbo and stock injectors if I do the coolant reroute?

I'm interested in keeping the injectors stock for awhile to save the $$ on the injectors themselves up front, save $$ on a crossflow fan or something similar up front, and have lower HP until I get more track time under my belt.

I guess one issue with my plan is that it also doubles up on tuning time and cost...

Does it get pretty hot where you are? I don't think i'd run a stock radiator on track period, personally... let alone when boosted.

It's fine you told the op your opinion. I disagree with your opinion since his motor appears to be fine. So do others on here. For what it would cost him for VVT he could have bought a stand-alone, tuned his car, and have better numbers than the vvt. He's not trying to win nationals here just have a functional reliable car.

For what a vvt would set him back he could buy another motor and blow that one too. And he can giggle around every turn and forget about his vitals for another go at the track. Or he can buy a vvt that has 50k miles on it ,spend 3 times as much, and do something stupid and blow it up.

If you don't have money for injectors, wait to put on the turbo. What's the point if you're only going to be able to run 5psi? Get the MS, learn to tune, get a good radiator (the stocker won't cut it on track with boost), coolant reroute, and learn to drive the car NA. A turbo track car is not something you can squeak by on with the bare minimum, or it will end up costing you a lot more in the long run.

hey man I am just another miata owner wanting to tlak with others, Man I have had miatas' for 15 years, and have done it all bro, where do you guys get off talking down to an active auto-x, miata builder and owner like you do? you guys are true cock mouths and shouldn't be on this forum, god knows if I were running it, the first stupid ass post you ould have been gone,
I have been met with nothing but disrespect on here, just because you don't like what someone is saying you reem on them, use constructive critisism, Don't be an asshole, I would put a whole years pay on out racing and out building all the smart asses that think they know about this car,building and racing, I do this as a hobby and I have done nothing but give advice, didn't reem on anyone didn't put anyone down, but multiple people have towards me. those are the people that should be kicked off this forum.
And if you have something to say then come on down to key west FL, we'll meet up and i'll out do anything you think you can do. out build and out race you, or I'll give you my car. that mouth is writing checks I bet your ass can't cash, lets hear that mouth run when I sho you up, then all you will come with is excuses.
Come down here, show up, shit I'll come to you smart ass.

Aluminum Ebay radiator is cheap ~$100. You mite be able to get away with stock rad at lower power as long as you have an under-tray but not something I'd really mess around with. It's well known the cheapo aluminum ebay rads are used on some track cars.

:bowrofl::giggle:

:rofl: If he doesn't respond again we know it's cause he broke his keyboard. or the QC bot got him. Take it ez there breh. Anyway I think the op has decided in the direction he wants to go.

https://www.miataturbo.net/megasquir...-vs-ms3-76037/

link form inside that thread http://www.msextra.com/feature-xref.html

Link at msextra goes over all the actual technical differences.

Rev puts some magic into his boards so the above link comparing features may be a little different. Consider that when working with him.

Sure is Flurduh in here.

I'm not to say anything negative to someone when they give an opinion on what they thing about someones' build ect. everyone here could learn alot more if there wasn't so much B.S on this forum. multiple things I have seen on here like, go get a standalone and learn how to use it, some one off post about post counts, ect, what is that crap?
Actions speak louder than words,breh,,,,, you got something negative to ay, then come down here and be about it.. period.
shit I just want to give insight and get it from other miata owners and their experiences with their cars, their builds, and tech questions, not put up with nonsense, like psi has nothing to do with it, positve pressure has every damn thing to do with it amateur.. please stop with disrespect, be informative, be helpful, take advice, or nothing. why waste peoples time with blah?

Oh yeah also the best way to search miataturbo is to go to google and type something like below in the search. It will search the site miataturbo.net for compression test. I havne't searched via the forum search in many years.

"compression test site:www.miataturbo.net"

FWIW with respect to the stock radiator, I can say that I definitely overheated with a literally stock one, because its 17 years old, but an OEM-style replacement has done quite well for me this season, at least N/A. Since my... incident last year, I was very careful to set up my ultragauge to alert me to overtemps, and I had a passenger monitoring the gauge for a session or two.

Just as a data point, a Tyco OEM-style replacement radiator on an NA motor with ambient temps in the 90s in Alabama running for 15-minute sessions every hour will not break 212F at all and will mostly hover around 200F while actually driving, and be back to 194 (where my thermostat holds) by the time you're back in pit, so for an N/A vehicle, the stocker style is plenty.

I suppose I could just save up and go full bore, do the radiator and injectors and everything all at once, and just try to have some self-control as I keep learning on the track.

In any case, this is good food for thought, thanks guys.

Err.. and by all at once, I meant run the ms3 n/a first, and then do the rest, of course.

So give some. Stop blowing hot air and actually give some useful insight. Expect to get called out on bullshit fluff posts today, and at any point in the future on this site. Fluff and special flower posts are not what we're about.

You want to learn? Then bend to the way of the forum and revel in the fact that this is the best performance-oriented forum for this platform on the entire internet. Or do your best to get mad against the way this forum is run, don't fit in, continue to make stupid posts, and either rage quit or get banned. It's how it works.

Judging from your posts and how you react to being called out in general, you'll want to point your browser to ClubRoadster.net Main. You can be the big fish over there.

FAIR enough. I also need to take into account that a different forum has been run a certian way for how ever may years the most senior people have been running it, I shouldn't speak out on something that

Go read through the entire thread after you've had a glass of kool-aid and you'll see nothing that harsh has been said. you appear to be grossly overreacting. and PSI is irrelevant if we have no clue what turbo the dude is going to be running. 10 psi on an efr 6758 or 10 psi on a gt2554? huge difference.

Sorry your ego feels so abused but I honestly don't see anything worth being upset about.

I'm not fully aware of, although I do disagree on how my post have been reponded to, maybe next time I can think about re-wording them, to give a better description and insight in one post.

I get worked up easily, and have done everything with a miata from V8 swaps, to just simple turbo installations of just about every kit there is for these cars. And got rubbed wrong when someone posts stuff like that, because it really comes off like disrespect.

We are all enthusiasts here, there should be a mutual respect, and for those that are new to miatas we should be as helpful as posible, that's all I'm saying.