Have I reached the limits of an SC12?

[Ben Wilson]

Just dynoed the mr2:



As you can see the power curve is climbing nicely until 6k then it just stops. I'm sure a non heatsoaked intercooler and running in shootout mode would give me bigger numbers, but the 'wall' at 6k would remain.

I'm thinking either my 2" pipework is too small, or I've hit the wall with an SC12.

Here is the engine bay:



Opinions/suggestions?

[mullett]

I've spoken to a guy who seemed very knowledgable, said that about 160hp was the safe limit for the SC12, so I'd guess you're damn close to that at the wheels, let alone the flywheel. Go for an SC14 man, you know you want it. Or bolt on a T28 and laugh all week...

RM.

[30psi 4agte]

I would say yes too! What bbost was that on? You could upgrade to the s14 but you need to ask yourself how far do you want to go with this setup as the bigger SC will prob only get you up around 160 kw ( IM just guessing about the s14 limits someone may no for sure what they are capeable of) if you are after more then go turbo for sure!!!

123rwkw may sound small to the guys who go around quoating kw figures like i have hot dinners ( massive plate!!! ) BUT for the guys who give real numbers and are dyno proven GET major respect from me!!!!!!!!!!!!!!

123 rwkw is a gutsy effort M8 Keep it up

[Hen]

I have never heard any reputable numbers higher than that from a supercharged 4A. So it's impressive. But that doesn't answer whether it is the limit of an SC12.

However I'd say that you would be pushing the limits of what one of them can do.

What is the SC speed when you're at 6000rpm?

Hen

[Rallystanza]

I have read and seen things in the past such as a friends dyno chart (AE92 4AGZE) which illustrate the dreaded ZE 5500rpm, or there abouts, "drop off" in power. This has most commonly been traced back to a faulty knock sensor. Are you still running a stcok ECU? The stock ECU brings in a fail safe measure for knock that effects the power around this region.

Just another thought,

Jeremy

[mullett]

SC12 maxes at 12,000 RPM from memory, so you could run a 2:1 drive ratio if you're keen and only going to rev to 6000. If you want a water to air, I've got a 2" one here for $250 with a pump etc. After that, maybe 2.5 piping is the way to go. I would think that you're approaching the maximum theoretical power, considering you must be close to 200hp at the flywheel, which is far more than most people get. For reference, my GZE made 129hp at the wheels in factory trim with a pod and exhaust (including mega$$$ cusco extractors, came with the car...score) on a dynodynamics shootout dyno.
So you've come a fair way from there, I'm impressed. I'm tuning mine next week (I made LESS power witha 165mm pulley), and before I build the 7A-GTE I'm going to bolt a T3 to my GZE just to see what happens..

RM.

[Ben Wilson]

I'm using a 175mm crank pulley (mr2 supercharger pulley), a Haltech and I've got water injection running before the SC, I'm still only getting about 12psi though.

I've just managed to find an old dyno plot and I copied it onto this one for comparison:



As you can see at around 4400RPM the power gain is massive (from 58 to 102kW), but the gain tapers off in the top end. I'm thinking about sticking some pressure guages through the inlet system and seeing if I'm getting any measurable losses along the pipework.

[TooF]

no i dont believe you have... scott is getting 138ish from his sc12... im trying to find the graph atm..

[wiso]

if your only using a nevo, a nevo still isn't designed to spin the charger fast enough to really kill it, or even max it out early. it would more have to do with your air flow i would think, your pipe size.

Gunmetal gets 140rwkw off his setup, and his uses the standard sc12, with a nevo, and his still has plenty ot power up high, but that may have more to do with the amount of internal mods his engine has

[myne]

whaaaaa :"(

[mullett]

looks like someone lifted off on that run...

RM.

[nick.parker]

Hi Ben,

Your kW effort is really good. I would guess a bit of SC belt slip was happening right at the top end. Other possibilities could be boost leak, or what is you ignition timing mapped like? Perhaps you could do another run, but log manifold pressure too? Or on the road watch your boost gauge around 6000rpm. Though this is not substanciated, I have heard that the stock bypass valve (even with the ABV mod) can leak above 14psi, which is higher than your boost, but I just thought I'd mention it. Do you still use the stock ABV? Have you ever heard any detonation (probably hard to hear at 6000+rpm).

This is my SC14 AW11 dyno. It is less power than yours (112kW) but I'll partly explain. This is with 14psi (would you believe) and bad tune (thanks to a stuffed AFR meter on the dyno I went to, which was reading too lean, resulting in the car being tuned too rich (10:1) and a stock exhaust (with 'freed up' ;-) cat though). Just thought I'd post it now since I'll have another one in a week or so to compare it to with new extractors and exhaust and better tuned. By leaning the mixture back out to around 12:1 using a trustworthy wideband it goes noticibly better since this dyno. I also put a shorter duration inlet cam (than the Wade 267) in which improved low/mid torque a heap and dropped boost to 12psi. I expect to be around (170rwhp) 125kW @ 12psi, so next up a bigger crank pulley to bring the boost back up to 15psi, at which point I think I'll have 180+ rwhp. Anyway thats enough speculation from me for now!




Cheers, Nick

[Ben Wilson]

Apparently I goofed on the comparison graph, I assumed the previous run was hitting the rev limiter when it was hitting the 180k speed limiter, so I redid the graph:



I tightened the belt this morning and it feels a little less breathless up high, I'll have to get it to a dyno day sometime and try it out. That being said, I've decided I'm happy with the power for now, I think it's time to enjoy it

It uses a BOV instead of an ABV, and it's running mid 20's for advance up high. They dyno operator said it just seemed to love more advance, but he wasn't game to dial any more on. Bear in mind that was the 17th run of the day with no fan or water spray on the intercooler, so I'm sure bigger numbers ar possible...

[YLD-16L]

Hey Ben nice work!

Just a comment on the 2" pipe work, I don't believe this will be a restriction at this stage. My 4A is running 2" pipework in the engine bay and sees around 170rwkw (with a turbo and not an SC), so you should still have some headroom with your pipework

[Ben Wilson]

Sweet, that's exactly what I wanted to hear. If I've reached the limits of the supercharger, there's not much more I can do, and I really don't want to rebuild the inlet system again...