Very good question and I have also pondered over this to the point of dissapointment that I didnt dyno my car before modifying it.

I have a 1998 E36 323i.

I have a K&N ( shielded ) CAI
M50 manifold
Stainless exhaust manifold, sport cat and scorpion back box.
APtuning remap.

She is currently producing 197.4 bhp with 255NM of torque.

I am very happy with that result. With regards to remapping Naturally aspirated cars I think it is more of the transformation of power delivery than solely power increase. With modifications I believe that the remap benefits them all greatly and makes the acceleration and peaks of the gear range better and smoother. :thumbsup

I hope this helps a bit.

I have my dyno graphs in the Tuning forum in the dyno thread.

 

Thanks for that mate. Looks like it's worth getting done then.

 

They can lose power of time from wear, intake runners gunking up, cylinders coking up, tolerances wearing out, but there is usually a decent spread of power figures around an engine, probably +/-5bhp which can be due to inaccuracies.
Before and after runs will show you the total increase even if all the numbers are a bit off.

It's the final transmission losses that cause the problems, they are always best guesses / estimates, so even if you get a low figure on a dyno, remember it had to estimate the losses and can quite often be a few bhp out.

Even the temps of the engine will make a difference, cold will give lower figures which the thicker oil, as it warms up it'll get to a perfect operating temp and then work the best, and then heat up further due to the fact you struggle to get the same airflow from a fan as you do driving, the tyres can heat up from getting pinched between the rollers and it'll start to lose power again.

 

Glad to help. I have never heard anything bad about remapping ever other than people maybe being a bit disillusioned that a remap will turn there car into a rocket ship.

I noticed your forum name,are you a para or ex para?

 

I'm 3 PARA mate. Still serving though with just over a year to go to my 22.

 

Happy days, I am a ( hat ) VM in the reme. I have 13 years left til the end of service :frown,I still enjoy it though :hihi

:thumbsup

 

i don't know if 12-15 bhp is whatyou will get?? i would have said more around 5-6bhp with a different in drivability and response!
i wouldn't consider a re-map with out first giving the car a full service if its not been done for a while and also put on any mods i may want to get the best from the tune up! as said nearly all cars lose bhp, i had a cavalier sri 130 years ago with 85k on the clock, i had a filter, full exhaust and chip, by the common concenses my car should of had 155bhp, but it was rr'ed at 142bhp.

if you want a bit of extra power i would suggest a 2.8 transplant!, engine swap like for like. if you want the car to fell a bit more responsive get the remap.

 

My car is 17-18yrs old and has an Endtuning chip and Dave-F induction kit and was rolling roaded at between 212-218bhp...the engine has always been looked after with regular oil changes and good sparkplugs etc..etc..considering it should be around 192bhp from the factory it shows that they don't nesseccarily lose HP....another one is Steve23002's car which had a 218bhp RR...and his car has a chip,Dave-F and Decat exhaust and his car is the non-vanos 325 too....:thumbsup Also Mistreku's 325 pushes out impressive figures-he has done a fair bit too it though :thumbsup

 

same with mine is's done 130k and at the rr day i was jokingly saying to stk and steve "here we go 150bhp" when it was on the rollers but i was surprised to see 198.8bhp from an engine that needs servicing and only mods are a filter and cat back exhaust

 

If you want your car to keep it's power you need regular servicing and you need to use premium fuel. Anyone that does'nt and then shells out for a remap is really spending their money on the wrong things.

 

Deffo. I always use decent fuel in the 325 and the oil gets changed every 5 mins...:thumbsup
Keeps them tip top for not much money...

 

just like to jump in and say that my 17y/o 320i with cheap cone filter (no heat sheild) and universal back box made 161bhp on dyno last weekend but my is low mileage and has been serviced regular so i would say that they can lose power if neglected but if looked after it will maintain or even gain a couple of ponies as it loosens up lol, i did the logical thing and dyno'd it before i start and will again at verious stages through tuning so i can see exactly what mods give what power gains

 

i did the logical thing and dyno'd it before i start and will again at verious stages through tuning so i can see exactly what mods give what power gains

I take it this dyno is where you put it on rollers to find out its BHP and the likes? How much does this cost and what types of places do it? Where would I start to look to getting it done? Thanks.

 

Cheers mucker. One good thing is I'll be able to get my M3 with my pension gratuity!

 

:cool What model are you thinking of? I would love an M3 :jaw-dropping

 

i don't know about other cars, but i've been talking about this with the guy from evolve, they're mainly focused on Bm's and they test lots of them daily.. Most of them will push the manufacturer specified power, even after 150k. usually, the losses are minimum (2-3hp). so, i wouldn't worry too much about the power loss and would go with the remap. :thumbsup

 

Looking at getting a 2003-4 E46 M3. Should get a decent one for around £12-13,000 in a years time. I love the E46 shape and the E46 M3 looks even better!

 

Nice choice mate, now that is something to look forward to and a reward for your time in the club :thumbsup

 

Have a look at fitting the 328 exhaust as well.

Ian

 

What part of the exhaust would I need?

 

You'll need to investigate further but IIRC you need the cat and back.

The 328 is twin pipe all the way through.

Ian

 

Few on ebay for under £150. Cheers mate.

 

Get back on ARRSE you!

 

Fuel wise, if you're running "good quality" fuel to protect the engine all well and good.

One thing I would say though (which is possibly less true of newer engines with knock sensors) is run the fuel the car was tuned while running.

I've come across people before getting cars rolling road mapped and then saying "and now I'll see how it goes on higher octane fuel"

The answer to the above is slower!

 

I've come across people before getting cars rolling road mapped and then saying "and now I'll see how it goes on higher octane fuel"

The answer to the above is slower!

Can you explain why please ?

 

You running the M52TUB25 engine?
I can happily say that mine has been RR'd (at 146,000 miles) at 180bhp 181lb/ft torque.
Same engine in mine, i believe. Thats standard. No mods whatsoever.
So, after 11 years and a lot of miles, i'd say no, that it doesnt lose much in the way of horses, but as with any mechanical pump, you gotta look after it...mine is cosseted, but it gets used. (brands hatch in the first week of ownership always shows up the weak points..)

 

One thing that people have to understand is that the octane number isn't the amount of octane present, it's the ratio of octane to heptane that provides a similar knock resistance.

Knocking or detonation occurs when the temperatures and pressures inside the cylinder get too high and part of the fuel mix auto-ignites, this then starts off a chain reaction where the shockwave of the ignited fuel sets off the fuel near to it, and it passes through the mix at the speed of sound burning everything.

Normal combustion is "deflagration" where a flame front passes through the mix in a controlled manner.

This is burning things by passing heat onto the nearest cool neighbours. With detonation, the remaining mix is just under the auto ignition temperature, and the shockwave pressure is enough to tip it the final amount.

If you lit the corner of a piece of paper, it would deflagrate by the flame slowly incresing in size and spreading.
Detonation of paper would be when the sheet burns from one side to the other at supersonic speed.

Back to the fuels, higher "octane rating" fuels can resist the pressures and temperatures better, which allows you to advance the ignition, and start the burn earlier.

The faster an engine turns, the less time you have to extract power out of the expending gasses. The speed at which they burn doesn't change much and you need to get the pressure up nice and high for when the piston is at between 13-16 degrees of crank rotation.

This can be thought of like pedalling a bike, if you push hard when the pedal is pointing directly up, you'll just balance and sit on the top.
The best leverage you'd get on a pedal would be when it's at 3 o'clock, but as it's a drawn out push, rather then a quick bang, you get the most useful "work" done when you aim for peak pressures around 14-ish degrees.


The spark will occur before the piston has even reached the top of the cylinder in preparation to get this peak pressure in the right spot, and the faster the engine turns, the earlier you need to start the burn to get it to land on the sweet spot.

When the octane rating is increased, you can start the burn earlier without fear of the mix exploding by itself when the pressures get high, and one way to increase the octane rating is to slow the speed of the burning

Aside from increasing the amounts of harder the ignite components in fuel, you can also get a couple more octane points by slowing the burn instead, and it's this slowing that can reduce power.

Most petrol fuels are blended in such a way to keep the flame front moving at the same speed, although there is quite a few places out on the net that are under the impression that octane number is directly proportional flame front speed.

There are infact some racing fuel blends that have very high octane numbers, and high flame front speeds.

 

Well put.

Bassically if you tune a car with one fuel octane rating, then run it on a higher octane fuel, all things being equal the mixture will be being lit too late, effectively behaving as if ignition is too retarded and hence slower

 

All my cars runs better on shell fuel. Second choice would be bp but mainly shell I use. I get slightly more power from using it compared to other petrol stations. Also my engines seem to last longer using shell fuels.

 

Also my engines seem to last longer using shell fuels.

If you mostly use Shell how can you tell?

 

hi
(1)do you need to put high octane fuel in for a a bmw 320i 170bhp tre-map?

 

Not usually unless it is pushed to the absolute max