I think I want a blow job
 

Nothing extravagant, just 75ish on top of my 140. Cheap, simple easy. Snails or clams? I'm leaning to a hot side M45 just cuz it's cheap and easy. Oh, management is handled.

What have you done to get to 140? What model Miata do you have?

In before "only fags go super".

Your whp figures are generous.

The only things I can think of which would get a naturally-aspirated Miata engine anywhere near 140 HP would more or less preclude the use of forced-induction.

We need to know a lot more about your engine.

10:1ish and cams on a 1.6.
Couldn't be much different than blowing a VVT motor :confused:

Don't the 1.6's make like 85hp at the wheel? That's one hell of a cam.

I love this fucking forum :bowrofl:

blowjobs for everyone from op

Sure

https://www.miataturbo.net/attachmen...ine=1314404884

nasty

What you need is..............
https://www.miataturbo.net/attachmen...ine=1314409464

If you want 160whp find a used M45.

Just word of warning, that's going to be pretty boring.. I know from experience.

160 won't cut it. Gonna need to be 200-220

when it comes to this, you don't want cheap and easy. you want experienced and gentle.
just get decent engine management (i.e. MS)

Why no turbo? Doesn't get much easier than that.

I'll sell you this for $450.00:
http://jugrnot.com/IMG_2158-1.jpg
1976 truck motor, 350, 4 bolt, wedge heads, Weind dual plane. Made 196hp/280tq in a 1974 Olds Cutlass. We discovered the camshaft was flat and only opened the valves about 1/4 the way. Installed a stock L31 truck cam and dynoed 248hp/310tq.


Quoted for truth. A "hot side" MP62 might get you close to 220whp, but its going to cost about $3000 bucks and up.

El oh fucking el at nawzz gif

got nothing against turbos. I've just done a decent amount of development to get my exhaust where it is. That would mean starting over


I don't do double wide's

No offense, but what "development" on the exhaust have you done?

*shrug* That motor has around 500,000 miles on it. Looks it, doesn't it? You could probably weld the hood shut on a vehicle with that motor installed and never mess with it again. Cut an access hole for oil filling, of course. ;) Figured I'd offer.

don't care about V8's in the least bit.

1 5/8 stepped to 1 3/4 long tube header, to 2.5

edit
I want to add 6-10# of boost on to what I have. If it's snails or clams I don't much care. I'd prefer clams because I know I can out flow it with the current exhaust.

hahahahaha

Uhm, ok. I was picturing something a bit more radical when you claimed 140HP.


Well, to be painfully honest, the motor you have now isn't exactly ideal for forced-induction of any kind. And a 10:1 engine is going to be even less tolerant of the scorching-hot output from an M45 than a stock engine.

That said, basing your turbo vs. SC decision on the fact that you already have a fancy exhaust manifold seems a bit short-sighted to me. I see no reason why you couldn't sell the manifold you have now to some kid over at CR.net, and that would eliminate your barrier to entry.


I'm trying to be objective here. You're starting with a worst-case-scenario engine (a high-compression 1.6 with unknown and presumably high-overlap cams) and saying you want to make more power on it with an M45 than a typical NB engine equipped with an MP62.

If I were you, I would seriously consider selling the entire engine and picking up a used stock 1.8 engine, preferably an NB. If you find the right buyer, you could probably break even on the deal.

El oh fucking el at nitrus pic hahahahhahahaahahhah

Could always swap in a rotary.


Anyway, Good luck. You'll need it.

The overlap isn't that radical. Besides the gears can dial some of that out. If not an M45. What turbo will start into positive pressure around 15-1800 and not run out of breath @7500

what do NB M62's make?

Let me spell this out, cuz you aren't getting the hint. YOU AREN'T MAKING 140WHP

really?

https://www.miataturbo.net/attachmen...ine=1314458955
that was with stock electronics and an AFM :fawk:

so now the question at hand. What's the most cost effective way to force feed this thing with 6-10# of positive pressure

^With a turbo. And you only made 130whp, on a dynojet.

With a turbo. You will not make 200whp on an M45, it simply does not move enough air. I'd find a GT2554R, but even then you're not going to be making power at 7500rpm.

what speed does the 2554 start falling off?

A little past 7k at best. It's a small compressor. It won't feel like a big turbo up top - my 2871R feels like a god damn freight train up top compared to this.

https://www.miataturbo.net/attachmen...ine=1314465783

edit: This is my old setup, so
'99 longblock
BEGi mani/DP
stock IM w/ VICS switchover at ~5400
genuine GT2554R
eBay IC
MSPNP
Rx7 460s
~15psi

how badly does it fall of between 7k-8k? I need to be able to get to 8k(gearing limitations) without loosing too much power after the peak.

Don't know, never had the desire to spin my motor that hard. Could be doable, could fall off like a rock.

Be realistic with your expectations - you aren't going to find some random turbo that makes boost at 1500rpm but still pulls hard at 8k+. The 2554R will give you near-flawless response and still pull fairly well up top - everything bigger will give you a little more top end but impact the low-end and response in exchange.

I'm not asking for boost at 1500. Just positive flow to negate my vacuum. and get back towards atmospheric. (yes I know it's technically boost)
The engine base should be able to fill in the bottom grunt some. So running a slightly larger turbo that didn't go positive until 2500ish would be alright. I just don't want to deal with an engine that all of a sudden "comes on" like Vtec.
I guess my main realistic power band is 4k-8k

Unfortunately, you just can't have everything.

I'm not entirely certain that you understand the dynamics of how a supercharger works, so forgive me if I'm being obtuse, but I need to make sure we're all on the same page here.

Any given supercharger is capable of supporting a certain amount of HP. I think you may be under the impression that installing, say, an M45 on any engine will automatically raise that engine's output by 60HP or so, and that's completely inaccurate. A much less inaccurate (though still vastly oversimplified) explanation would that an engine with an M45 on it will make about 160 HP, regardless of what the engine started with. You take a 100 HP engine and put an M45 on it, you'll get 160 HP. You take a 250 HP engine and put an M45 on it, and power will actually drop to 160 HP.

Why is this?

Horsepower is made by burning fuel. And to burn a certain amount of fuel, you need a certain amount of air. If you move more air, you can burn more fuel and make more HP. Broadly speaking, it takes about 150 CFM of airflow (measured at atmospheric pressure) for every 100 HP you want to make.

Now, positive-displacement superchargers (and, to a slightly lesser extent, centrifugals and turbochargers) have a hard upper limit on how much air they can flow. For every rotation of the screw they move a certain volume of air, and just like piston engines, they have a redline. An M45 moves 0.75l (0.0265 CFM) of air per revolution, and it redlines at about 14,000 RPM. So that's a theoretical output of about 371 CFM. Unfortunately, Roots-style blowers in general are massively inefficient. You might get 70% efficiency out of the compressor itself at the flow levels you're talking about, plus another 30-35 HP in parasitic load just to turn the thing.

That's fine and well for relatively small, low-output engines turning at low RPM. But if (hypothetically) you were to put one of those on a 250HP V6, it would actually be a restriction.


The MP62 is better in all regards, but the combination of it and your engine still isn't going to make 200 HP. You are going to be detonation-limited by your high CR, and boost-limited by your cams. IOW, a lot of that air/fuel mixture that we worked so had to squeeze into the engine is going to blow right out your exhaust valves during the overlap period, and what's left is going to detonate.


FastForward, which is considered by the supercharger-fanboys to be the pinnacle of forced induction technology, claims 190 HP on an NB.



No offense, but I don't believe that dyno chart for a moment.


Cost effective meaning cheapest? That's easy. A Bell "Shangahi-S" turbo kit. $1,435 with the Chinese knockoff "T25/T28" turbo if you provide your own engine management (which you said you already had handled) plus whatever it costs you to hang an intercooler. And subtract whatever you sell your fancy header for.

If the theoretical output is 371cfm and 70% would be 259cfm. That seems to make the available power I need :confused:

100% VE = Ci x RPM/3456 (correct formula?)

so for me 1639cc = 100.01 Ci

rounding 100 x 7950 (potential RPM) / 3456 = 230.04

seems like it's on the edge of maxed out, but potentially viable

:shrug: nothing I can do about that

nice

Don't interpret what I wrote literally. I was mostly just pulling round numbers out of the air from memory for the purposes of illustration, and the reality of a running engine never matches what's on paper.

There is a sufficiently large body of empirical evidence to support the fact that an M45 is not capable of making 200 HP that you simply need to forget about it. You might be able to hit your power goals with an MP62 (emphasis on might) but it's very iffy, and would certainly not be cheap or simple.

ok

I need to find the numbers. I do remember the 70% drop as a "standard"

using your numbers and this equation
REQUIRED AIRFLOW (scfm) = 2.723 x HP x BSFC

190hp with .5 BSFC would need 258.69 CFM. (still pondering)

these seem to agree with your memory (sort of)
http://www.rbracing-rsr.com/turbo/TurboMaps/M45flow.gif

http://www.rbracing-rsr.com/turbo/Tu...s/M45power.gif

benchtop racer... if you don't want to accept what people with experience and knowledge are trying to tell you... you'll just end up with a M45 and a detonating engine.

it'll be fun to blow up

Even at 310cfm, and a .5 bsfc, you're looking at ~227bhp at best. Knock 15% off of that and you're at 185whp, which is about 10whp more than I've ever seen an m45 produce.

Empirical evidence says you won't break 200whp with an M45. If you want 200-220, you need an MP62 or a small turbo.

200-220 makes it easier with my weight. That's my basis for those numbers.

Easier for what?

To go fast. I think he's trying to say he's on the mighty porky side.

^thaT

Diet and exercise?

not doubting you. But searching the dyno's on M.net with M45 as the key word. Brings up a few who have gotten into the 180's. Is it the dyno, the operator....:dunno:


um, no

Can a mod move this to the SC section

Since the empirical data says my dyno numbers are inaccurate. Then I'll challenge the empirical data to break 200 with an M45

Thanks Joe

:popcorn:

The best of luck to you. And I'm being serious/not snarky/whatever - best of luck to you.

If you break 200 with an M45, you'll be doing something common knowledge believes impossible.

However, I imagine coming close to 200, let alone breaking it, is going to cost big $$$ if it's even possible on a M45.

The idea that a M45 will make any engine only make 160hp is just flat wrong.

http://www.trackdogracing.com/websit...9_M45_8PSI.pdf

There is a M45 SC and a Shitty Power card making 196 and a half HP. But that is on a 99 motor. Not sure you are going to get any where close to 200 out of a high compression 1.6 even with a turbo.

And there are several M62ed and MP62ed cars WELL over the 220-240 HP range, I personally know of one that is making 300.

Now back to the topic at hand. Sell your motor or put new pistons in it, slap a turbo on there and call it a day.

I could live with that

Then you would need to do a 99-00 1.8 swap or even better do a later VVT motor swap.

nope. I'll keep plugging away at the old POS 1.6 everyone hates.

I don't hate it. You just seem to want to take an unnecessarily difficult pathway to reach a VERY easy to hit goal. But to each his own.

not unnecessarily difficult. I have the engine, management, exhaust, and a blower for mock up. Just need to find a take off kit.

PS, check your PM's

I got your PM. And 1) just because it works on a Honda doesn't mean it will work on a Miata. 2) I have NO IDEA what his power numbers are 3) I have NO IDEA what he is using for forced induction. So not sure what your point is. I think you have a very reachable goal. Just think you are going to need to make some changes to your current set up if you want to do it with a M45

doesn't mater what the numbers are....it proves you CAN run FI on a high base compression.

Yes you can and nobody said you couldn't. But you aren't going to hit the numbers you want to hit with a high compression B6 and a M45. You can run FI on a 14:1 motor....but just because you can doesn't mean you should.

just gotta do it and find out