No problem at all, just wanted to save you some money.

We all are excited about a real ECU tune it's just been a very long and expensive and at least up till now unproductive idea.

So please continue but you certainly have an idea what everyone has been through and we still have nothing.

Good luck!!
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Lets hope they dyno some good numbers. Then we'll know that it's worth spending the money to do it and we'll all be happy,including ECU Tuning Group. I hope it works out for everyone.

Talk to you later. Have a great day.

OESIII

 

OESIII, I appreciate you taking the time to share your experience. I don't have the technical know how of most of these guys, but am interested in other owners experiences. I am considering putting some mods on my STR so I find your posts informative. Most of the guys/gals in this forum are top notch. They question stuff which is a good thing in my opinion. I too feel more comfortable with stats in my face, but shared info can be just a valuable, IMHO. Thanks again for your posts and I look forward to the dyno test.

 

So, yesterday I visited HPA Motorsports to have my (Stock+Qwiketz+K&N) STR dynoed. These people convert stock VW's into racing cars for a living, with 99% of their customers coming from abroad, mostly the USA. As Avos has noted, the HPA dyno is world-class.

Before we began, Marcel Horn the CEO and chief brain said:
"First of all, we want to use 2 axles to avoid any problems with ABS. Second, if this car came from the USA (it did) and is now using Canadian gas, be prepared for a low reading of up to 60 HP less than you expect. For some as yet unknown reason, we are finding this to be the case with cars that we tune. If we go across the border to Washington, fill up with 92 premium and re-test the car, we get an immediate increase in HP, with less sensitivity to temperature increases.".

What the f***, I had just paid my $175 and always use Chevron 94. Let's go. So, we ran the test and, sure enough, the result was 340 CHP! I was so pissed! Then Marcel said:
"If you go across the border, fill up with 92 RON in Washington, and come back here, we will run another dyno at no charge to prove my point.".

Interesting offer, but no way, Jose, I am far too busy and in any event do not plan to keep filling up my car in the USA.

So, my next question was "Should I go for an ECU Tune?" and his reply "Waste of money if the tuning software was setup for use in the USA".

So, last question "Should I fit this 1.7 lb pulley". His reply:
"Up to you - you will gain some low-end torque, but probably lose HP as revs and temperature increase.".

The good news - the car is driving like a dream. I'm going to fit the pulley, and then decide what the next step, if any, should be. Sorry everyone, does not look like I'm able to make a useful contribution to the subject of ECU Tuning.

 

Thanks for posting that. If nothing else it shows that this is not a trivial issue.

When you say CHP is that what I've seen called rwhp? If not, is it one of those figures where you take rwhp and add 20% (or whatever other figure)?

I think the USA doesn't normally use RON (we do) but rather AKI or something (92 RON is about 89 in AKI or whatever the pesky thing's called - both RON and it are called "octane" by many locals just to confuse things).

 

By CHP i think he means crank horsepower, so he likely made under 300rwhp?

Post up the dyno sheet if you can.

 

He made 340 chp which equates to 400 rwhp= despite the K&N a/f and modded air intake tube his STR put down the manufactures advertised chp. The dyno operator suggests American 92 octane (premium) fuel as a means to gain the well deserved 60 hp increase in chp= 460 chp or 390+ rwhp. Otherwise, Robins' STR is running fine on Canadian petrol.

 

JagV8, I have always understood that chp was "crank HP" as opposed to rwhp, which is "rear wheel HP", and I asked that specific question and the answer was "Yes, we are reporting crank HP". I guess the dyno software already added 17 - 20% to the HP measurement at the rear wheels.

As far as octane is concerned, both Canada and the US use the AKI (Average Knock Index), which is the average of Research octane number and Motor octane number. They are measured by 2 different test methods. Research is usually about 8 higher than Motor so, if Motor is 90 and Research is 98 then the AKI is (90+ 98) / 2 = 94.

By the way JagV8, my mistake - he said "fill up with 92 premium gas", not 92 RON, so that must mean 92 AKI.

Finally, bfsgross, I think you have it the wrong way round - 340 chp is actually more like 280 rwhp.

 

I always thought CHP was crank hp, or flywheel hp or brake horsepower (bhp might read a bit higher).

The proper way to convert rear wheel hp into advertised flywheel hp is with this formula:

A= parasitic drive train loss of transmission (i.e. avg is 13% for a manual, 18% for auto)
B=rwhp from dyno

B/(1-A)

so a 340rwhp motor with 18% drive train loss would be:

340/(1-.18) = 414 crank hp

Things get tricky when figuring out true drive train loss, hence the reason you see car manufacturers using engine dynos.

Happy mathing. *If anyone wants me to create an excel file that will yield this conversion instantly, please let me know and I can e-mail it to you.

 

I also thought that was what CHP means, but I wanted to check since it's not readily measured on an actual car!!

I wonder what the ZF 6HP26 and other parts actually lose. An overall 18% may be right but it could be quite a bit wrong.

I've almost always seen rwhp measurements, which I don't see here. If chp is reported I take it with a large dose of scepticism and look at rwhp LOL

 

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Have to agree with that - if only because 340 rwhp was exactly what I was hoping to see and exactly the way the car feels after qwiketz + K&N, I am going to revisit the shop and double-check the result.

 

Hey everyone:

I don't want to be picky,but if you take RWHP 340 and multiply it by 18% you would come out with 401.2 CHP. That's just about right on the money for manufacturers' stock specs.

I've spoken to several dyno techs from different garages and two said for an automatic you should multiply RWHP by 18% to 20% to come up with CHP. One tech stated that with a six speed tranny it's more like at least 25% times RWHP. So it would be 340RWHP X .25 drivetrain loss = 85. 85 + 340RWHP = 425CHP.

There has to be a difference in drivetrain loss between four,five and six speed transmissions and I'm inclined to believe that 18 to 20% is more standard for a four to five speed whereas the tech who stated at least 25% for a six speed is probably correct.

Ah,the mysteries of the STRs and their baffled owners!

Talk to you later:

OESIII

 

Robin, please don't take this as disrespectable or an attack upon you: I did mean 340 rwhp not 280 rwhp. There's no way in hell your STR is putting down less than 300 rwhp following your mods due to the Sport Shop/Dyno Shop's malarky they're trying to sell you on Canadian petrol holding back 60 hp. If it should ever leak out to her, the queen of England wouldn't have any of this and would order the immediate severing of their heads for such blasphemous statements and excuses for their incompetence. No one deep inside agrees that there's a 60 hp deficiency from the Canadian fuel. Can one imagine what car manufactures must claim for their cars sold in Canada: "Our 350 hp 2012 Mustang GT 5.0 will blow your mind", whilst the 5.0 bangs out 412 chp in the U.S.? The dyno experience/operator etc. are at serious fault of testing your STR chp/rwhp. Your STR must be putting out at or near 450 chp or 390+ rwhp, and you admittedly feel this. The dyno shop botched. It often happens, and this is the very reason for such a discrepancy amongst dyno results from all makes of vehicles. You deserve a re-dyno at no cost, on a double axle dyno, in 4th gear, DSC off, in between runs turn the a/c on and spray cool water on the intercooler radiator, and place a bag of ice on each charge cooler. Or...just use your butt dyno. Pull up to a stock 2003 Mustang Cobra and honk the horn three times then nail it. You should dust him.

 

Hey OESIII, there is no nice way to say it but your quotes response is tainted with incorrect information. please done take offense, we just need correct info to flow through this forum.

Auto transmission usually have between 17-20% drivetrain loss, while manuals are 12-15%. My previous F-Body brethren nailed our manual six speeds down to 12%. The speeds of the tranny should not have an affect on the drivetrain loss, but it is instead many things: torque convertor, engineering of tranny, drive-shaft, differential, rear end setup, wheels. There are are a lot of variables, hence the reason why manufacturers use engine dyno numbers and not rwhp. A subaru STI or Mitsu Evo can have up to 25% drive train loss, again showing how we need to know the actual parasitic loss value. Stick to 18% unless someone has an stock engine dyno and a rear wheel dyno to compare.

From my formula, which takes the weighted value of the integer (multiplying does not), shows that 330rwhp should net about 400chp through 18% loss. If I remember correctly, 330rwhp to 340rwhp is the average for a stock STR which matches the math within margin.

I made a sweet Excel file to calculate all of this at work if anyone wants it, let me know.

 

Whoever this clown is, he now has zero credibility. More than likely the two samples of gasoline came from the SAME refinery. Canada has a enormous supply of crude oil, the US has tremendous refining capability so the gas you buy at your local station probably came from the US.

That aside, there's no difference anyway. 94 is 94, 92 is 92.

Just splitting hairs but AKI is Anti-Knock Index.

 

Drivetrain loss depends on the dyno you use, here is a good explenation:
Roll Diameter

On the single drum per wheel dyno, i usually use 17% (this is on a 30" drum), which is not even conservative. So 340 rwhp on this type of dyno is 340/0.83 = 409chp. On dual drum per wheels it goes up, could be even 22%, but don't quote me on that as I have not enough experience with these type of dynos, and am not interested in these.

Some do a rollout test to verify the drag of the drivetrain/tires and then calculate the engine hp (chp or bhp), but also this imho doesn't give a good value as it is not with a load. So that is why I always only want to measure 1 axle and only a 1 drum per wheel dyno.

 

Well, I got confirmation that what was measured was 340 chp, not 340 rwhp.
Something stinks, and I think it's the dyno. Like Mikey says, 94 is 94.

I am definitely not going to waste any more time and money on this venture, and I will not be spending $1000 for an ECU tune. I am going to fit the 1.7 lb pulley, and use butt dyno measurement. One day, I will test the cats for blockage, but the real jewel will be the twin-screw S/C. Avos, are you there?

 

Can you post the dyno slip? Have they measured the a/f ratio? What correction factor did they use?

A TS is indeed a way to dramticaly increase power, but it also comes at a cost, so for most this will be out of reach.

 

Robin, pop on the 1.7 lb pulley, hi-flow cats, Maganaflow Tru-X center muffler (has built in x-pipe), hard re-set the ECU, then Hang-On! I'm estimating 450 chp @ nearly 500 lb/ft torque. The beautiful thing about this small motor is that it's a DOHC 4 valves/cylinder, blown, quick winding super breather that puts down immense torque at low RPM's. Though she churns 2.89 rear cogs, the blower coupled with the ZF's low 4:1 1st gear makes it all feel like a big block at launch time, then an auto bahn cruiser after 4th gear, with a power band seemingly nowhere in sight. Where can one get all this plus a beautiful exterior, interior, ride, all for $15,000?