Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Supercharger Discussion (https://www.miataturbo.net/supercharger-discussion-38/)
-   -   Noob, Rotrex SC options (https://www.miataturbo.net/supercharger-discussion-38/noob-rotrex-sc-options-95149/)

kamel6k 12-04-2017 05:42 AM

On a stock vvt head, forged 9.5/1 pistons, 2.5” exhaust, smallest pulley for 120000rpm @ 7200rpm, we are seeing 270hp (crank, because that’s how we measure it in Europe) power delivery is so smooth, I would say. 74 is a waste of time. Looking for options to hybrid it to a 94.

BTW, from the original Kraftwerks kit, nothing is left from the kit, at this power level.

Goingnowherefast 12-04-2017 07:12 AM


Originally Posted by bschonman (Post 1454847)
I'm personally trying to keep the car streetable and therefore have as much low end torque as a rotrex car can have. Any recommendations for pump gas? No e85 around here. And my want for low end torque rules out cams, right?

Use stock cams. Consider the TSE Turbo kit if you want torque. Personally I'm going with Rotrex for the ironic lack of torque, in hopes of keeping a motor alive for more than two seasons per rebuild.

18psi 12-04-2017 11:40 AM

>wants low end torque
>considering hands down least low end torque providing f/I application

lol

Braineack 12-04-2017 12:48 PM


Originally Posted by 18psi (Post 1454976)
>wants low end torque
>considering hands down least low end torque providing f/I application

lol

I don't see the problem. he can spool his rotrex with compressed air.

Braineack 12-04-2017 12:49 PM


Originally Posted by Goingnowherefast (Post 1454940)
Personally I'm going with Rotrex for the ironic lack of torque, in hopes of keeping a motor alive for more than two seasons per rebuild.

you know you can do this crazy thing called: tuning.

DNMakinson 12-05-2017 06:20 PM

Guys are keeping this entertaining

OP, what about your son’s set-up that you don’t like?

Exactly what problem are you trying to solve?

bschonman 12-05-2017 06:28 PM

I enjoy rotrex for it's lack of torque as well. Notice how I said "as much torque as a rotrex can have". I'm not looking for the 300wtq a efr would easily give me. I find my rotrex infinitely easier to drive on track than my FM2 car making a similar amount of power. Every time I push the pedal, I immediately get the same response. Maybe it's because I'm a novice driver, but I just prefer that. 250whp is 250whp however you get there.

bschonman 12-05-2017 06:31 PM


Originally Posted by Braineack (Post 1455006)
you know you can do this crazy thing called: tuning.

A motor making 220wtq will always have a longer lifespan than the same motor making 300wtq. Tuning fuckups can melt a rotrex car the same way they would a turbo car.

paNX2K&SE-R 12-05-2017 06:39 PM

This may be a silly question but why don't people ever run the C38 size units on Miatas?

Chilicharger665 12-05-2017 07:47 PM

Heads don't flow, so no need. Plus weak transmissions are always an issue.

Bmiata40 12-07-2017 11:16 AM

Back to the injector question. I have the options of 750cc or 1000cc at the same price. Does it make sense to just run the 1000's and not look back? I'm not sure, but I've been told that idle can sometimes be a problem with the bigger injectors. Seems to me that with the ms2 less on time should be fine.

Braineack 12-07-2017 12:10 PM


Originally Posted by bschonman (Post 1455315)
A motor making 220wtq will always have a longer lifespan than the same motor making 300wtq. Tuning fuckups can melt a rotrex car the same way they would a turbo car.

again: tuning

https://cimg8.ibsrv.net/gimg/www.mia...e4d807c855.jpg

sixshooter 12-07-2017 04:07 PM

1 Attachment(s)
If they are ev14 injectors the 1000cc will idle fine

1.9Conekiller 12-07-2017 06:15 PM

https://cimg5.ibsrv.net/gimg/www.mia...461bce5f8f.jpg
https://cimg8.ibsrv.net/gimg/www.mia...c11fc00946.jpg
Never followed though with a build thread, in fact I think this is my first post :party:
essentially I have a nice churbo build. Lots of influence from previous builds i.e. 18psi style intercooler routing.


Originally Posted by DNMakinson (Post 1451321)
Does your son have a build thread here on MT.net?

I suppose the thought is that the Rotrex will have low enough torque at low RPM that it can boost up to 300 whp at high RPM without bending stock rods?


bschonman 12-09-2017 08:35 AM


Originally Posted by Braineack (Post 1455669)

What are those graphs showing? Is that controlling boost so it builds gradually to redline? Why would that be preferable over a centrifugal supercharger? Wouldn't the torque still be as low?

Braineack 12-09-2017 12:13 PM

I'm just saying, if youre worried about tq, you can tune torque.

poormxdad 12-09-2017 06:38 PM

Brain,

Your plots show that the tune increased boost on a turbo'd car, which increased hp and torque. On a Rotrex equipped car, would a superior tune increase BOOST over an average tune?

Thanks,

Braineack 12-09-2017 07:28 PM

a turbo doesnt have to run full boost at all times. If you have an EBC, you can tune the boost output. If you're worried about too much tq, dont let the turbo produce too much torque.

Goingnowherefast 12-09-2017 10:13 PM


Originally Posted by poormxdad (Post 1456056)
Brain,

Your plots show that the tune increased boost on a turbo'd car, which increased hp and torque. On a Rotrex equipped car, would a superior tune increase BOOST over an average tune?

Thanks,

No. The boost that a Rotrex unit produces is a direct relation to the engine speed (rpm) and pulley size (ratio). No tune will change the amount of boost you make on a Rotrex.


Originally Posted by Braineack (Post 1455006)
you know you can do this crazy thing called: tuning.

Can tuning change the laws of thermodynamics to fix the inherent massive heat issues that accompanies turbochargers? No doubt, I think turbocharging is better for the OP and anyone would plans to do more street stuff than track stuff. But between turbos falling off (fixed by inconel studs and better hardware), cracked manifolds, High CLT's and oil pressure, high IAT's, wastegate issues etc. you have to at least admit that the Rotrex systems have some appeal to the track only guys. People that want to just stick it on, tune it once, and never have to worry about anything at the track except for suspension/tire setup and driver mod. I was able to hop in a Rotrex car and go extremely fast within a lap, and I'm not the only one that has that same story. Rotrex cars are just easy to drive fast on track without issues.

sixshooter 12-09-2017 10:19 PM

:jerkit:


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