About a year ago I had my V-3 Vortech'd stock-block Revup Z dyno tuned and made 425RWHP and 315lbft at 7000RPM. While happy with the amount of horsepower, coming from my broken Turbonetics kit I found the torque levels pretty disappointing. Overall it's still great to drive but lately I've been yearning for a bit more low-end kick.

I started looking at other Vortech dyno results and it seems my torque figures are abnormally low in comparison to others. My gas mileage has also suffered badly since the tune, even in comparison to the Turbonetics kit. Could other Vortech owners check this dyno sheet and tell me if something seems to be off? PSI seems pretty steady so it doesn't appear to be belt slip. The only thing I can think of would be ignition timing being lacking in the midrange. This would definitely affect torque and would likely bring down MPG as well.

I also know that the tuner didn't touch the cam timing, because he did a half-assed job outside of everything except HP at redline. Could experimenting with the cam timing make the ~30lbft difference in the midrange? I'd think not, but it's worth looking into.

http://imgur.com/a/2TEV4

 

I should note that this is all Osiris tuned so I can mess with it a bit. I have tuned motorcycles and my old turbo 240sx, so I do have some tuning experience. However I have not tuned anything making this much power on a stock block, hence my asking before messing with it. If this is normal for a "safe" tune I'll leave it.

 

I see your only making 9.8 psi. So for that level I assume you have stock pulleys. If so, that's not a bad dyno.

The most important info you're missing AFR's and Ignition Timing Advance. Also, to compare dyno numbers to someone else on a different dyno at a different time does not mean much. Dyno's don't mean much anyway, they are just a tuning tool. More Important is how does the car drive and feel.

If your MPG's are down, then it rich. What do your exhaust tips look like? Are they black? They should be almost clean with just a small amount of soot. Plugs should be the same with just a bit of color.

The easiest way to raise low end tq is to raise the boost with the next size smaller seep pulley.

Note: I've never touched my cam timing.....

 

Agreed, I thought that was a pretty good HP number for less than 10PSI, but it just seems to lack some midrange grunt that some other Vortech Zs show in their dyno. Even comparing the shape of the torque curve without numbers make it look like I might be missing something.

Cruising AFRs are mid-high 14s last I checked. The tuner didn't seem to do much partial load tuning at all, so when I got the car back it was running low 11s putting around town. I did a few hundred miles worth of mixed driving datalogging, adjusting, repeat and got to where I am now. I should note that I did not change any high-load/high-rpm cells and only street driving parts where it can be safely datalogged on the street.

When I ran a Haltech with the turbo setup, it would follow any target AFR as it's a full standalone. With the Osiris, I read that even with targets set to a high number the base coding on the ECU won't allow it to exceed 14.7AFR. Is this true? If not, then that's likely the culprit there if it can't go into a leaner burn under very light loads.

Exhaust tips are a bit sooty, but nowhere near as bad as it was when I was running 11AFR. They do get gross since I don't have cats, but once cleaned it takes a good while for them to turn black again.

I'd love to go to a smaller pulley, but on the stock engine I feel I'm pushing my luck as it is. I've got all of the supporting parts (fuel pump, 750cc injectors, Uprev's MAF, oversized intercooler, heavy duty clutch, etc) but I'd worry about increasing boost past where I am now.

Edit: As far as feel goes, it's all very "linear" feeling. The power delivery is very very smooth and if you didn't hear the blower whistle you might think it was stock. It all feels ok, but I guess I'm just looking for more midrange than the Vortechs normally produce at this boost level.

 

More detail about supporting parts. What Intercooler, Fuel pump, Headers, ect.

If done right, this is what a stock block can take, and I've got a Non-revup.
Attached is my race tune (left) and street tune (right)
Note: that on the left side of the graph are the different scales for WHP, Wtq, Boost, AFR's, ect.

 

That's amazing. I was just reading your build thread and can't believe that's achievable without blowing anything up. Your tuner must be very good. Also is the V-2 blower different than the V-3 or is it just the oiling system?

Your boost also seems to build differently from mine. Maybe the smaller pulleys are really just necessary for these things to really wake up. Your boost builds completely flat instead of curving upwards, and your torque curve flattens out sooner than mine. Very impressive numbers all around.

I'd have to check the intercooler, it's been a while since I've had it all out in the open. It's a 4" thick core bar and plate type, I don't recall the other dimensions offhand. Fuel pump is a standard Walbro 255, headers are factory for now. Front half of the exhaust is a custom true dual 2.5" system going back into a Borla rear half. The single turbo kit of course changed all of the forward piping of the Borla kit, so when it was switched for the supercharger the piping had to be redone.

I need to continue with more research. Last I read 400WHP was about all anyone dared go on a stock block. Maybe that was referring to turbo'd cars, which make much more torque (and cylinder pressure, which breaks things). I'm not opposed to building the engine if needed for reliability, but I almost think that to justify the price of good pistons, rods, studs, etc I'd almost want more power...vicious cycle. For those levels I'd probably go with a TT kit at that point.

 

I'm the Tuner.

The V1, V2 and V3 refer to the type of gearbox. The Trim refers to CFM. I have an old V2 SC-Trim rated @ 1000cfm, you have at least a V3 SCi-Trim rated @ 1050cfm.

The quality of the Intercooler plays a big part in HP. There are 3 types of bar and plate IC's, low, mid and high Density Cores. I have a Medium density 4-1/2 x 12-1/2 x 22 core. My ATI's @ WOT, 4th gear, and full run are only about 8* above ambient. I should note that a Low Desity IC in the size would be about 40-50* above ambient, robbing 6-8% Crank HP ( at 500 crank HP, that's 30-40HP)

 

Wow, excellent work! Wish you were in AZ to tune mine.

I'll head out to the garage to see if the nameplate on the supercharger indicates which compressor wheel is in it. I bought it secondhand and didn't realize at the time that there was a difference outside of the gearbox itself.

You're really tempting me to make bad decisions here and swap to a smaller pulley lol. I was reading you have 50+ pulls, lots of hard driving, and over 40k miles on this setup without issue. That's just crazy, I thought I was pushing the limits here with mine.

 

The nameplate only states V3 SC, though Vortech's site only lists the SCi and Si so I presume it's one of those and not a one-off freak part. The impeller has 8 blades if that's any indication.

 

I could be that they made a V3 SC, they just don't make that anymore, now it's an SCi.

 

Yeah, hard to say for sure without comparison pictures of them. Thanks for the input on all of this by the way, it's greatly appreciated.

I'm re-reading the Vortech FAQ on here and even on the first few pages there are people worrying that the 2.87 pulley is dangerous on the stock engine. What changed? I'm not doubting you at all; I'm genuinely curious because I did my research when I bought this and at the time it seemed that 400ish HP was about as high as you could go safely. Is it just midrange torque from turbo systems that tends to bend/break rods or have tuners gotten that much better?

 

Theirs a limit to everything, but I think most of the VQ engine problems on this website have been from inexperience, improper setup and bad tuning.

 

I've driven several SC'd vq's over the years, one of them 450whp plus (while owning two turbo'd vq's) and SC'd vq's have always felt sluggish to me <4k rpm. Even more sluggish than N/A in some cases. There might not be much you can do except drop a pully size or two.

 

My vortech dynos are all on paper so I will have to dig them out of my old paperwork mess. Thought I scanned a few but I guess not.

So with stock pulleys you actually have a decent dyno. With the vortech the tq is usually 70-100 less than what your hp number is. The reason for this: Torque peaks in middle rpm range then tapers off. With a vortech you aren't building any significant boost in the mid range (boost builds with rpm) therefore in the 4000-5000 rpm range you are probably still in the 3-4 psi range so no big bump in torque. Now nearing redline when the boost keeps going up if you compare your torque to the torque of an oem dyno you are making more over stock in those areas.

Turbos will produce boost quickly and in that mid range so it provides a significant bump in midrange (which is where peak tq is).

So other than going to a smaller pulley to increase boost in that midrange (and across the entire board) you don't really have a way to increase the tq. Depending how conservative your tuner is there might be a little timing left but if you aren't an experienced tuner and don't have anything to log knock I wouldn't push the limits too much in that area. Cam timing will essentially do zero for your tq issue. Cams will do more for a turbo than s/c since turbos spool based on exhaust gases. So you can get a little more spool out of a turbo by playing with cams.

 

This is on a DD dyno that reads low compared to the DJ dyno I had done.

Either way you can see the difference in tq for hp on a vortech kit. This is with a 2.87 pulley. It pulled just over 500hp on a DJ dyno with that same tune.

 

Thanks for your reply and the dyno printout. I do understand that the lump of midrange torque I'm after won't happen with a centrifugal supercharger, but it does look like the 2.87 pulley will give it a respectable amount of kick. I figured cam timing won't do too much at those RPMs but thought I'd double check. Do you have a built engine with that 2.87 or are you also stock block?

 

Here is my old vortech dyno with the 3.33 pulley on uprevs dyno. After I switched it out to a 2.87 pulley, I ended up with 418/352 @11psi on same dyno. The 2.87 really opened it up. Instant difference as soon as I switched.

 

That was a built engine, heads, cams on pumpgas.