There could be two things going on here. first of all, I would be concerned about the low HP numbers. its very rare In my opinion, for a dyno to register such a low number for our cars. they should all be 320ish RWHP on any dyno. if they are not, then there is something wrong with the dyno or something wrong with the car. The fact that the reflash changed the HP value, is an indication that it did work. However, the other possibility is that the gains only brought your engine to "normal" levels. that's what I would be concerned with. I would go right out to find a dynojet chassis and do a retest now, and if what we are all saying is true, you will get much more than the stock'ish hp value. there is a slight chance that the dyno software was not calibrated for the device conducting the test. (very slim chance of this) OR, you ran the test on a very hot day, at altitude , with a lot of humidity, and you got the actual results, BEFORE correction factors were applied. (correction factors, sometimes called SAE values, take into account the air density, temp and humidity and give a pretty accurate adjusted value. This means on a normal or "Standard day" of near 70 degrees F, if you were to do the dyno again, there would be no correction factor and the actual HP would be much higher vs the day when the test was done and you needed a huge correction factor.) However, usually the correction factors are less than 3-4%, unless you are doing the test in Denver.
Most all the dyno sheets ive seen for our car are in the 320rwhp range, so If I didn't see that, I would be a little bit worried and get a second dyno run somewhere else and evaluate if something was off with the tune of the car , or a mechanical issue. also, keep in mind that the gear the dyno run is made in, can cost about 5hp per gear below 5th gear. strap down and how the test is conducted also can cost hp . High temps in the engine, can cause timing and mixture ECU changes that can kill hp. Monitoring these factors is important, independent of the intake air temps.
So, if you have a dyno run with a vantage of 280rwhp, and we all know the engine should make 380 at the flywheel.... you have to ask yourself, where is that 100hp? (when the missing hp should only be about 40-60hp, and its not constant for any RPM, it changes with speed as well.


For those of you bold enough, and have a safe stretch of hyway available, do a test from 60mph to 100mph. if you can get there in just under 7 seconds, one gear to redline, you have 320rwhp. (or 60-80 in 3.2 seconds if you are not that bold and have someone video tape your speedo for later review and timing)

 

another major point to make here is regarding the shape of the HP curve.


the OP original dyno run shows very little HP in the 6000rpm range. (on the order of 240rwhp) this is very low. the video attached shows rwhp in the 300plus range from 6000rpm to 7800rpm. (a much flatter hp curve , and flat torque above 250, not in the 200 range as the OP test shows.)
its all about the average hp you can make over the operational range in any gear. our gears are pretty close together, so the range you will care about, is 6000rpm to 7500rpm . take the high and the low valve and average it out, and that's the power you really have to use. vs the hp of a car with a flat hp, or bell shaped hp curve, that's going to be a HUGE disadvantage in a race condition.


this video looks like the same dyno as the OP used, but its hard to tell. same style anyway, right?


what about this one. shows a 4.3 on a dyno dynamics
https://www.6speedonline.com/forums/...manifolds.html


Here are the dyno runs from this thread and the one from a manifold thread. notice the baseline dyno runs are very different. Because they are done on the same type of dyno, I would be worried about the baseline.

 

Looks like we've got two different conversations going on here. I'll be starting another thread specifically about dyno numbers. If dyno posts are relevant to this convo, please continue! If they're about dynos in general, please see the new thread. Thanks

 

Hi guys,


I did my ECU tune at Eurocharged last week on my stock 2008 V8V Roadster, and I am amazed and shocked by not only the numbers but how the car feels. It feels much faster and torquey, sportshift gear changes are much smoother. Both Slav and Vlad have been amazing.


I had by full service done first (except air filter, didn't arrive on time, so original 2 year old filters were in the car). Then we did a dyno before ECU tune and after the tune. Here the screenshots and video.


Before ECU tune: 325.3 / 0.8 = 406hp




After ECU tune: 341.7 / 0.8 = 427hp




Video of the final dyno after ECU tune:

 

Nice numbers! Thanks for the before and after pics!

But if your car was stock, how's it putting out 406 hp? I'd imagine a .85 drivetrain conversion would be more accurate... that'd put stock at 382.7 hp and tuned at 402 hp (still similar gains, but I'd think a more accurate total hp figure).

 

And that was my first question, how is that possible? Is your conversion correct? Maybe 15% loss? Maybe not so stock (I'm the 2nd owner)? They were also surprised but said no it should be converted at 20% loss and same as sryan14610 Aston. Everything is properly calibrated.

 

Its at motor, not at wheels:
The grey Vantage (18°/ 973 mBar):
mot: 330.3 hp
wheels: 278 hp
361 Nm

The white Vantage (32°/ 961 mBar):
mot: 269.7 hp
wheels: 344.8 hp
378.3 Nm

i can post the dyno if you will

 

There are a lot of variables that affect drivetrain loss, but the rule of thumb I've always heard is 15% for manuals. 20% is very high. Our cars have a pretty direct link to the pavement!

When I was building my Subaru, it had a 2-piece driveshaft. You could get a 1-pc carbon fiber driveshaft that basically gave ~5% increase in whp. It didn't add any power, it just reduced drivetrain loss. Our Vantages already have a 1-pc CF driveshaft (prop shaft), and are only RWD (not AWD, like Subarus), so there's a lot less drivetrain loss comparing our cars to those.

 

remember , drive train loss is VERY gear dependent not like wheel weight which is reflected through the gear box. So, in most gears above 3rd, driveline weight is really a non issue, and wouldn't show up on a dyno in 4th or 5th gear, even if it was a 10 lb reduction of flywheel. given the driveline is small diameter, call it insignificant, and certainly NEVER worth 5% of anything! really!

 

Yes, lets see the dynos.. these look like some sick vantages. power is very low at the wheels.

 

yes, Telum01 is right. drivetrain losses not only are variable,(at least 50% of them are), but are on the order of 15% for a manual, max. 5% of that is rolling friction and that goes down to only 2% at the slower speeds.
20% is very high. think about how much heat would be generated in the transmission if 20% of the 400hp was lost in the gear box. its more like 12% with 2-5% due to rolling friction

 

SportShift counts as manual?


So closer to 14%-17% loss...

 

Yep, it's technically a manual transmission.

 

Yes, a SportShift is a type of manual. The automated portion only relates to gear selection and does not affect the transfer of power from the engine to the tires.

 

and why do you think your '08 made as much as the other vantage after the ECU tune, even before it was tuned?


yours went from 380 flywheel to about 400 flywheel using the 15% factor, which is about right when you look at comparing peak HP in 4th gear at near redline. confused how the OP's vantage could be so low, especially on a similar dyno