Five Oh Brian

So, I got this month's issue of MM&FF magazine in the mailbox yesterday and they have an article on the brand new Vortech V-3 supercharger. The V-3 is identical to my V-2, except that it has its own lubrication so you don't have to punch a hole in your oil pan. They have the standard (non-intercooled) like I have and the V-power (intercooled) is optional, just like the V-2.

The cool part is that they took an all stock 05+ GT and dyno'd it on a Mustang Chassis Dyno at Vortech's facility, and then dyno'd again with the V-3 standard and the V-3 intercooled blowers. I had been wondering if my dyno numbers were low a few weeks ago (351 rwhp on a Mustang Chassis Dyno), but recently have learned the the Mustang Chassis Dyno reads lower than the much more common Dynojet (about 10% on average!). I did a google search on the topic, and found that 10% figure on just about every brand of message boards (Mustangs, GM's, Nissans, Honda, Mitsubishis, etc.). Seems like every forum has threads on the differences between load bearing dynos (i.e. MD) versus inertia dynos (i.e. DJ).

So, the stock GT they dyno'd spun 239 rwhp (they didn't say, but I'm guessing it was an automatic car based on that low of a number). The V-3 standard blower spun 329 rwhp (a 90 rwhp gain). This makes me feel much better about my 351 rwhp (about a 110 rwhp gain). The V-3 intercooled spun 371 rwhp (about a 130 rwhp gain). They said that 368 rwhp equated to about 480 flywheel horsepower (which implies a 23% drivetrain loss, yet another reason I think they were testing an automatic like mine). Ultimately, though, my 351 rwhp fits right into the rwhp #'s on the same dyno on an equivalent car, so I can sleep better now.

However, this information opens up a few questions to ponder now. For example, how much rwhp would my car make on a Dynojet (to compare better with the majority of guys who've dyno'd on one)? 10% more than a Mustang Dyno? That's 386 rwhp in my case. Also, does an automatic really give up 23 % in drivetrain loss (my tuner, and most people, say about 20%)? If Vortech is correct about the 23%, then that drives my 351 rwhp up to 455 flywheel hp (a 20% factor puts my car at 439 flywheel hp).

Ultimately, it would be cool to put my engine on an engine dyno to actually measure flywheel hp, but the cost would be so prohibitive. We do have a dyno shop nearby with a Dynojet dyno, though, so I'll be heading there soon to at least answer if there's really a 10% difference in dyno's.

Anyone here have the V-3 yet? Any thoughts on Mustang Chassis Dyno vs Dynojet readings?

JedCranium

Any pictures of the baby in the nest? Congrats on joining the FI club

Jed

Five Oh Brian

Thanks, Jed. Here's a short slide show of the V-2 blower in my GT...

http://s294.photobucket.com/albums/m...tangStills.flv

bigray327

Wow, that seems low. My V2 (non-intercooled) put 412 to the rear wheels on a Dynojet, on a very conservative tune.

TillmanSpeed

It all depends. The mustang dyno allows you to enter the vehicles weight and account for wind drag.

The dynojet unit knows the EXACT weight of the roller, and how quickly it is excellerated. This is uncorrected HP numbers. Then the dynojet weatherstation applies climate changes and you can select from a few different correction factors. We use SAE only, but alot of places will give you standard numbers, because it reads slightly higher.

You have to remember, if you have 100 horsepower and 20% drivetrain loss, you're getting 80RWHP. All you see is 80RWHP, not 100 flywheel. You cant say "okay I have 80, so add 20% (16RWHP)". That would mean you're only making 96 at the flywheel. You see where I'm going, right?

With your 4.10:1 gears and 18" wheels and tires, you may be seeing just over 20% drivetrain loss. 23% is probably shooting a little high, but it's safer for them to use 23% then it is to use 20%.

So figuring on a dynojet, you would have put down probably around 375RWHP at the most, assuming your dyno shop was doing everything accurately. Thats about 487/488 flywheel horsepower @ 23% percent drivetrain loss and 468/469 flywheel horsepower @ 20%.

So it's best to assume 468-488 flywheel horsepower. I would go off of the 23% because of your 4.10 gears. This all depends on what your car does on a Dynojet SAE corrected. That's the only numbers I'll use and only numbers I reccommend you use.

Regardless, thats pretty strong numbers. Got any dyno graphs with AFR?

The guy above this post (even worst case scenario) if his was uncorrected HP numbers, he'd still see around 400RWHP SAE. So that does seem a little low the numbers that MM&FF posted. Yet, I never believe a word they say. I know an article they completely stretched the truth about for a story, locally. And another guy they completely didn't credit for a transmission swap (his post is floating around MF).

Chris Rose
Tillman Speed Inc.
www.TillmanSpeed.com
610-497-5776

max2000jp

351whp seems a bit low to me. What pulley are you running? How much boost are you seeing?

My car made 475whp with the 10psi Intercooled kit running heavy Roush wheels. I have the stock 3.55's btw.

Five Oh Brian

Hey, Chris, thanks for chiming in. I have heard before that steeper gears (i.e. the 4.10's I have) will net a lower rwhp dyno number. I still don't understand why, as it seems that more twist from the better gears would actually yield better rwhp, but everyone says what you've said.

Also, I did dyno with the factory 18" wheels and tires (54 lbs each corner!!). At the track, I run much lighter 17" wheels, but didn't think to put those on for the dyno tune.

I'll have to post the dyno graph from work tomorrow (I don't have a scanner at home). AFR ranged from 11.1 to 11.6 throughout the entire WOT range (4,800 rpm's at converter flash to 6,400 rpm's redline). At light throttle, the AFR was 15:1 for (better economy and emissions?), and there's no detonation anywhere (no timing being pulled by the computer across the entire range, although we pushed it til it did, then backed it off).

Five Oh Brian

Keep in mind that my car is an automatic vs your manual, so I lose about 20-23% through the driveline, while a manual only loses about 15% through the driveline. Also, you have the intercooled blower, while mine is the standard non-intercooled blower so I can't run nearly the timing and aggressive fuel trims like you can. And your car is black, and we all know that black cars are faster!

And, as the MM&FF article pointed out, the same car as mine made 329 rwhp with the same blower that I have making 351 rwhp with the same style dyno, so it sounds like I'm squarely in the thick of things powerwise.

I'm also pushing that power through 100% stock exhaust, heads, cams, etc. I imagine if I made some key airflow mods, then the blower could really go to work and lay down some big gains.

I'm using the standard Vortech pulley. IIRC, it's a 7.2 stepup ratio (3.6 in the blower trans, and 2.0 from the crank/blower pulley). Boost during my dyno runs started at 5.8 psi when the converter flashes at 4,800 rpm's, then rose steadily to a peak of 10.5 psi at the 6,400 rpm redline. Hp and boost were still rising sharply at redline, so suspect if I bumped the redline to 7,000 rpm's I'd likely have picked up another 20 rwhp easy and approached 11 psi boost, but I don't trust the stock bottom end to hold up spinning that fast, so 6,400 rpm's is all I'll go. Plus, any more boost and I'd have tons of detonation and heat with my non-intercooled setup, so I'd rather be on the conservative side.

TillmanSpeed

Well, I'll tell you right now... your tune is REALLY conservative at 11.1-11.6 AFR. You should be 11.6-12.0. I'll bet you have very conservative timing as well. Regardless, that's probably good for 20RWHP or so right there. Your tune is very safe, and leaves plenty to be had. Your tuner didn't do anything wrong, just didn't get you the best numbers possible. I respect that.

Horsepower is calculated by taking the dynojet drum's precise weight, and the speed in which it's accellerated, and that's how the horsepower is calculated. When you change the ring and pinion, or use larger tires, it "pulls it farther" out of 1:1 ratio, so to speak. Thus, giving us slightly lower numbers than what you'd see with a (numerically) lower gear, and smaller tires.

Error404

interesting, I didn't know this! My previous setup was automatic transmission, stock driveshaft and 4.10 gears (with whipple @ 10psi) put down 445hp I believe. Here in a week or so, I'm getting it dynoed with a manual transmission, light weight driveshaft, and 3.55 gears. I bet the jump in RWHP will be a pretty nice gain just from the drivetrain changes! haha! Maybe 460?

TillmanSpeed

Conservatively. With a little timing, shouldnt be a problem to put down just over 470-480SAE and 480-490STD.

Examples:

2005 Manual GEN 1 Whipple kit seeing 10PSI: (Thanks Maverick/Paul M.!) Blue run is whipple's tune.


2007 Manual GEN 2 Whipple kit seeing 9PSI: (Thanks Tom!)

Five Oh Brian

Hi, Chris, here's the dyno graph. Impossible to read the AFR as it isn't scaled seperately at the bottom of the graph (neither is the boost which is the one climbing high on the bottom). I do have all the data on a jump drive in excel format that the guy tuning my car gave me.

The hp and tq lines require a little explaining. My stall converter flashes to around 4,860 rpm's, so you see an erratic reading at that point. Anything before that is partial throttle, anything higher than that is WOT. Car still pulling hard at the 6,400 rpm shut off.

TillmanSpeed

God, I hate MD graphs. It doesn't look that bad AFR wise, as it was probably coming down from closed loop, and the average says 11.7. There shouldn't be any fluctuation, though. All our graphs are starting in open loop, and stay consistent.

At any given RPM at WOT, the car should put down EXACTLY what the base fuel table is commanding. This means that the transfer function is spot-on. That's not happening on your tune. This leaves me to believe that you have plenty of room left for more. Again, there's nothing WRONG with the tune, it's just conservative... plus we've got a bad case of OCD when it comes to air fuel ratios.

I would actually be fairly happy with that tune for safety and decent power.

Chris Rose
Tillman Speed Inc.
www.TillmanSpeed.com
610-497-5776

Five Oh Brian

Thanks for reviewing my dyno sheet, Chris. Sure is a tough to read dyno graph - sorry! My tuner said he could certainly dial up plenty more power (like you noted), but he was happy to keep it conservative (at my request) as it's a daily driver car that has to live long term on the stock internals. His own personal car is a different story: Fox Body GT convertible with a stroker motor, Vortech YSI blower, pushing 1000 rwhp! And it's a great looking car - not just wicked fast. He fired it up and I started looking around for a top fuel dragster!