My BHP from custome code

moynas · Post by **moynas** » Thu May 12, 2005 6:22 pm

Had the polo on the rollers today heres the outcome,

1st run 105bhp at the wheels, ibft 96

2nd run 109bhp at the wheels, ibft 100

3rd run 152bhp at the flywheel

Been told that its more likely to be around the 140/142bhp mark at the fly,

so a slightly larger increase than icypolos but JBS wont take this in to account as it wasn't on there rollers, still would be good to have a shoot out one day!!

dubpolo · Post by **dubpolo** » Thu May 12, 2005 7:03 pm

I want custom code!

but I have no money!

as rob said at inters. Iâ€™m a typical polo owner now (saving to buy petrol)

do you feel the car is faster?

moynas · Post by **moynas** » Thu May 12, 2005 7:23 pm

To be fair it does feel slightly faster but not a great deal!

Does hit 60mph in second gear easy now!!

dubpolo · Post by **dubpolo** » Thu May 12, 2005 7:33 pm

have they changed the limiter aswell? in your opinion is it worth scimping money togeather for?

moynas · Post by **moynas** » Thu May 12, 2005 7:46 pm

Dont no really to be honest, If i had a turbo car id be sayin go buy it now dont wait for 2mo cos the gains are huge!

But as they are only 12-15bhp you dont notice it in speed just how much smoother it feels really!

If i had the choice again i think i would have put money towards some schmidt wheels!!!

But its personal choice at end of day! But still wouldn't mind it tuned up more!!

dubpolo · Post by **dubpolo** » Thu May 12, 2005 7:51 pm

Cams, port and polish and phase 2 next then!

NOS!

stuart_hatch · Post by **stuart_hatch** » Fri May 13, 2005 12:36 am

Thats an rather large transmission loss what percentage you using?

Id say it should be more round 125bhp at the fly

You using like 45% transmission loss :S

Should be more around 17%

poussou · Post by **poussou** » Fri May 13, 2005 7:43 am

Transmission losses on the car are around 20 HP...

To have a fly HP of 153 as you say....your wheel HP should be around 133 !!!

I find that once again hard to believe, specially since your 1st run as you say was on the 106 wheel mark, which is spot on for a standard Gti.

I know you are gonna take this the wrong way again, but there is NO WAY you can gain almost 30 HP at the fly from 1st stage tuning (meaning filter,chip, exhaust).Remember there are people in here that have even opened up they engines with P&P that don't get that much horsepower......

PhilGTi · Post by **PhilGTi** » Fri May 13, 2005 1:16 pm

stuart_hatch wrote:Thats an rather large transmission loss what percentage you using?

Id say it should be more round 125bhp at the fly

You using like 45% transmission loss :S

Should be more around 17%

What school did you go to then? 109bhp aint 45% less then 150bhp.. lol

Phill.

stuart_hatch · Post by **stuart_hatch** » Fri May 13, 2005 1:30 pm

Ooopsies, but you get the general idea!

moynas · Post by **moynas** » Fri May 13, 2005 5:29 pm

Stuart on the Gti its standard is 125bhp (give or take) at the wheel

So with a re-map, BMC, exhaust i dont think im standard anymore fella!

Poussou, At the end of the Day im a carpenter i work with wood all day long, when a tuner gives me a sheet of paper with these figures thats all i can go on!! (get my point)

Im learning more about bhp/ibft but i dont understand how it works fully cos its not my job! all i have is whats infront of me so thats what i go by believe it or not!

To be honest (hate to say this) its a polo at the end of the day it aint a scooby or evo so it aint gunna be super quick! ( the money ive spent on my gti i could own such a sweet RB5 scooby

)

If a standard Gti is 125bhp at the wheels and you say you lose 20%
Its gunna be 100bhp at the wheels not 106-109bhp, Got this off dyno website on how to work out bhp etc

125bhp (at wheels) -12%-10bhp = 100bhp at the wheels

you dont lose just 20 brake yesterday i was told you lose 20%, this is straight from a tuners mouth!

poussou that makes it 100bhp not 105bhp standard even you can work out! i no my car isn't 152bhp at the fly! fly bhp is an estamate unless its out the car hooked up on a fly wheel machine!! then you get the bhp for that!

People really cant do math on here

poussou · Post by **poussou** » Fri May 13, 2005 6:16 pm

moynas wrote:Stuart on the Gti its standard is 125bhp (give or take) at the wheel

So with a re-map, BMC, exhaust i dont think im standard anymore fella!

Poussou, At the end of the Day im a carpenter i work with wood all day long, when a tuner gives me a sheet of paper with these figures thats all i can go on!! (get my point)

Im learning more about bhp/ibft but i dont understand how it works fully cos its not my job! all i have is whats infront of me so thats what i go by believe it or not!

To be honest (hate to say this) its a polo at the end of the day it aint a scooby or evo so it aint gunna be super quick! ( the money ive spent on my gti i could own such a sweet RB5 scooby )

If a standard Gti is 125bhp at the wheels and you say you lose 20%
Its gunna be 100bhp at the wheels not 106-109bhp,

you dont lose just 20 brake yesterday i was told you lose 20%, this is straight from a tuners mouth!

poussou that makes it 100bhp not 105bhp standard even you can work out! i no my car isn't 152bhp at the fly! fly bhp is an estamate unless its out the car hooked up on a fly wheel machine!! then you get the bhp for that!

People really cant do math on here

Ok here it goes...

ALWAYS, manufacturer horsepower is announced AT THE FLY

The figures you see on the manuals and the magazines are at the flywheel as well.

Flywheel horsepower can't be calculated "on the car" and thats because the only proper way to do that is with a so called "bench" dyno, which is what automobile manufacturers have.You can't find that anywhere, but even if you could, you would have to remove the engine to use it...

What all the comercial dynos do is measure the actual "wheel" horsepower, which is also actually what counts, as it is the amount of power transfered to the wheels by the engine.

So we have:

Flywheel Horsepower=Wheel horsepower+Loses (transmition or otherwise)

Depending on the car and its subsystems, the difference in Loses may differ.Also, 4 wheel drive cars have bigger loses than 2 wheel drive ones (i suspect you understand why)

So the "kinda" flywheel horsepower given to you by the Dynamometer is "estimated" by adding the loses to the measured one.

NOW...That is also the point where many "tuners" cheat people.Some may take you to a "preagreed" dyno, where you can easy have a 100 HP car show 150 HP, by "adjusting" the loses and such...

In the case of the Gti,horsepower is given at 125 HP AT THE FLYWHEEL by the factory.Many have claimed higher stock HP but thats not the point now..By using the above "formula" and by a fair estimate of around 18-20% loses the stock Gti HP is around the 100 mark AT THE WHEEL.Now in your case, and since you had as you said the above changes to the engine, a WHEEL HP of 106 should give you around the 106+20%=106+21.2=127 FLYWHEEL HP mark (with the optimistic values).

My estimate is that your car should be around the 140 mark.Which considering the stuff you have on is pretty good.I really wish you could be here to do a run with me , just so to see that HP doesn't come around so easily,especially for this car.........unfortunately....

moynas · Post by **moynas** » Fri May 13, 2005 7:07 pm

I tell you what you have explained that to me the best way so far!

Thanks big help so around the 140bhp mark is pretty good fo my car!

you see when people hand over a sheet with loads of bhp and no one has explained before your gunna believe them to be fair! (must admit)

But With my 2nd run with 109bhp at the wheels my polo is on its way up agree???

I take back anything bad ive said to you poussou

poussou · Post by **poussou** » Fri May 13, 2005 7:20 pm

moynas wrote:I tell you what you have explained that to me the best way so far!

Thanks big help so around the 140bhp mark is pretty good fo my car!

you see when people hand over a sheet with loads of bhp and no one has explained before your gunna believe them to be fair! (must admit)

But With my 2nd run with 109bhp at the wheels my polo is on its way up agree???

I take back anything bad ive said to you poussou

No problem man.

Trust me, i've spent sooooo much time trying to tune this car, either i'm gonna become an expert, OR i'm gonna dump it over a cliff.

I was in the tuning state you are know before the camshafts so i can give you an estimate of your horsepower.

I DO believe around 140 HP is a REALLY good gain if you consider "some" of the Gti's are geting sub factory HP...Thats around 15 HP without even opening up the engine.

P.S. Something i also forgot to mention...By increasing engine power you also increase the amount of power lost, due to increased heat, etc.This means a 200 HP Polo Gti won't have just 20 HP loses....

david burton · Post by **david burton** » Fri May 13, 2005 7:58 pm

poussou wrote: WHEEL HP of 106 should give you around the 106+20%=106+21.2=127 FLYWHEEL HP mark (with the optimistic values).

erm... no - when you're calculating it UP from the wheels using the same losses you use a 25% increase from the wheel figures to the fly!

To give an example: If you had a 50% transmission loss and 100hp at the fly - wheels = 50hp, but to convert back you need to DOUBLE the wheel hp to get back to 100hp at the fly!

so with 20% loss flywheel to wheels:

4/5 x the fly = wheels,
5/4 x the wheels = the fly

so 106bhp goes to 132.5 bhp at the fly.
and 109bhp goes to just over 136 at the fly - an 11hp increase over stock.