rapidcossie

this thread makes very interesting reading...

i have had my car mapped on the road and on the rollers.

Both mappers are at the top of the mapping game espcially with cossies...


the map on the road was well done and the car drove well annd could be held at WOT at high revs in 5th gear with no det etc etc, it made 400 ATW.

After i had ran the car for over 5000 miles i decided to have the cam timing altered from the standard setings to ake the best of the high lift cams/veriner pulleys.

with the boost capped and the engine ran up N/a we ended up gaing almost 50bhp mid range and almost 20 at the top end with my peak power raising from 7k to 8k aswell.
there is NO way you can do this kind of setting up on the road as some tweaks from the cams were resulting in only 5 whp increases, but they were increases.

the turbo now spins up quicker holds more power at all points all the way to the rev limit

Am i mising something here or are setings such as cam timing etc just guessed or do have another way of measuring very slight increases on the road??

the car now has had other various tweek on the rollers and makes 453 ATW.

i know what some are saying about RR power figs and that they are just for pub talk but my car has been proven on woodbridge air strip and it now hlds the top speed record for any cossies fitted with a T4 turbo charger....so its proof that the rolling roads figs do mean the car is quick..maybe its just the rolling road im using?


i believe to would be almost impossible to have gaind this extra power while mapping on the road.

any thoughts?

i
cheers

euan

rapidcossie

just to throw a cat amongst the pigeons...

alot of my friend have scoobies..

one is mapped on the road by andy F, the car is very fast for the spec and makes good RR figs.

the other is mapped by steve simpson on rollers and shows poor performace on the road for spec but makes fantastic numbers on steves RR.

work that out?

WRX_Rich

iTrader: (5)

I think you have just made Andys day

he has argued all through this thread that a road mapped car will be faster on the road than a rr mapped car

Neilo

i think the main thing to remember is that if your getting up to that sort of power level then the mappers pretty much always use the combination of the two.

I agree with you in the setting up cam timings is pretty difficult to do on the road, but tbh, about 1% of the cars on here would have the ability to change cam timings via venier pulleys anyway.....its not commonplace, at least, not yet.

When i get my adjustble pulleys on im not sure how we are going to set it up yet....but that will come in time.

rapidcossie

what stops them from seeing power gains from altered cam timing?

Neilo

what do you mean? as in why so few have it? if thats the question then i think its just because its reserved generally for the higher end of the scale, all the top power guys will most likely be using venier pulleys, but the lower ones wont bother as its simply not justified (at a guess anything below 400bhp at the crank)

you could get away with advancing the timing via the ecu to a certain degree.

rapidcossie

advancing the igntion timing thru the ecu is completley diff from altering the cam timing...

about not many people using diff cam timing and pulleys i see what you mean...i thought you meant here was something stopping imprezas from using them.

Neilo

other than the expense, nah there isnt, just most people seem to get away with using the standard stuff...

only when it starts to get "serious" do people seem to bother.

Your cossie sounds pretty damn strong, so i would have expected it on that car to get the figures you have. (very impressive by the way)

ZEN Performance

Newage sti cars have variable inlet cam timing, controlled by the ECU.

The main thing preventing most people from using vernier pulleys is the cost and availability. Typically a set cost around £500+vat (you need 4!) and then there is the hassle of actually setting them. It's not as simple as just lining up marks as most of the commercially available pulleys don't have marks, and with layout of the cambelt you could be anywhere with the cam timing unless you measure it with a DTI. If you have actually worked on an Impreza you will appreciate how difficult it is to dial in cams with the engine in place.

Solid cam followers (on most Imprezas) means that cam swaps are not straighforward on an impreza, but it is something that more people should consider if they are looking for power.

Paul

rapidcossie

understand the complexity of cam timing etc now on scoobies...

thanks for the comments on my car..it is pretty strong!

going for 500 ATW next

hypoluxa

Is this the car that has the mechanical boost control problem? If so, then I'm surprised that your friend did not explain this too you, and the fact it was purposely mapped to run low boost on the road until this issue is rectified by it's owner?


Back to the question of road Vs rolling road, I was recently involved in an interesting comparison at a 'local' Subaru meet. 2 cars, one mapped on the road by a 'champion' of road tuning, the other solely mapped on the rollers (Steve Simpsons).

Now both cars were within a nat's gonad of each other - from any speed, in any gear.

Which is a little surprising considering the road tuned car's extra 25% capacity and turbo capable of flowing ~25% more air (2.5ltr/20g Vs 2ltr with a VF35)

Maybe these 'real world conditions' were out of solar alignment when the road tuned car was mapped? hmmm.

dynamix

iTrader: (3)

ah - that settles it then

rapidcossie

this car has alotmore than just a boost problem..

where the peak power is made has alot to do with it..

the power is also down about 40 bhp on what it should be for a fully worked 2.5 turbocharged engine runing that boost.

this car has a graph showing almost 500 bhp on steves RR but CAN NOT out drag a P1 with 370 MAX...why not? beacuse his power band is so short and he is changing gear all the time...?

the P1's peak power is 7.5k and it holds the power well.

unlike the steve simpson mapped car that falls on its *** after 6k?


both cars were power tested on the same RR in scotland and graphs compared..the STI made 385 ATW and the P1 300.

why cant the STI out drag the (Andy F mapped) P1? both cars starting in 2nd gear and going up to 160 ish?



steve has now mapped this car in various states of tune 5 times and it has never perfomed as it should IMO

hypoluxa

Surly you cannot be so naive as too believe that there is only one way to spec and build an engine? and therefor the sole problem must lie with the mapper? Do all 2.5's make identical power? and do all 2.33s run 9.1 second 1/4s? Has cam timing, compression ratio, ic efficiency, octane etc. etc. suddenly become irrelevant? Steve has mapped quite a few cars to well over 500hp, do you think he suddenly 'forgot' how to do it with this particular car?


So as you mention in an earlier post, you gained 50hp and an extra 1000rpm up top plus earlier spool. You are obviously aware of the gains (and therefor losses) to be had with optimized cam timing (50hp is possible on scoobs at this power level too). What timing is this car running? What's the compression ratio? After all as I'm sure all tuners will agree, you can only map what is put before you.

rapidcossie

i understand you can only map what your given...

doesnt answer any of my questions tho?

harvey

iTrader: (48)

As Paul highlighted, some ECUs respond well to dyno tuning and others not so well, however, I believe that best results, with a few exceptions, come from a combination of rolling road and open road mapping.
There is an informative article in this month's Jap Performance, page 120.

ex-webby

Interesting topic this one and certainly one that I doubt an out and out conclusive answer exists (apart form the fact of using both methods to a degree for certain applications).

From my own experience (and I have used both exclusively and a mix and match), I have been fortunate to have excellent results from both in isolation, but in recent years with my Spec C, this has been mapped exclusively on the Dyno itself BUT has been tweaked following data collected from the road.

Now... I dont have the technical ability or experience to comment on the +'s and -'s of this, but all I can say is that my car has never caused me any issues mechanically (in fact none what so ever), has been used more than your average "every day" car in competition stuff and IS very quick for what it is (as regards to it's modification level). In the right hands I doubt many a car at a comparative tuning level would keep with it and it has achieved 0-60 in 3.85s and 1/4m of 12.55s... also it ran at this years Tuner GP completing 60+ laps in a day during 27degs ambient temps (just to put some context in to my previous point about it's use).

How do you actually prove which way is actually the best? Personally, as long as the car does what it needs to and stays reliable that is all I can ask for regardless of method.

Personally I think the biggest decider is the ACTUAL mapper themselves, more than the method used to map (as regards to dyno Vs road mapping).