bighead

iTrader: (1)

Hi everyone, I have a P1 with the following mods
....APS intercooler, hybrid turbo(think it a VF28),scoobysport downpipe,magnet centre,blitz rear,APS cold air kit(K&N filter),
MRT inlet pipe,Walbro fuel pump, SX fuel regulator and Tek3 remap.
The car make about 340 bhp/294lbft torque at the moment
the power does not come in until 4000 rpm (around 200 bhp),I would like to bring its lower down the rev range( driveability).
Would changing the ecu to motec/Gems or link help?
If so which is best.
ps the car flies after 4500-5000 rpm
any advice most welcome.
cheers.

[Edited by bighead - 9/3/2003 10:25:37 AM]

Andy McCord

clicky

Harvey, just edit my reply & note were the brackets are added

[Edited by Andy McCord - 9/3/2003 1:56:16 PM]

nom

Drive very very carefully until you get a remap. One of the reasons that the car is 'going well' at the moment is that it'll be massively underfuelling. I have heard of a fair few P1s blowing up (quite reasonable under the circumstances) with the APS kit as it changes the airflow. You may have been lucky so far, but even if it doesn't blow, you are causing huge stresses to the engine which will make it far more likely it lets go later.
Back to the question - the actual ECU won't make a lot of difference. The Link - the simplest & cheapest of those listed - would easily do the job. Other add accuracy/gadgets that you wouldn't really need at this stage, but might want later.

Brun

Errrrrrrrrrrrrrrrrrrrrr

harvey

iTrader: (48)

What Nom says is spot on. For my expensive experience with the APS CAK look here.http://www.scoobynet.co.uk/bbs/thread.asp?threadid=241405 {Can someone tell me how to make it clickable please} Page 3.
Current car spec www.geocities.com/harveysmith3000
I currently have a Link but hope to fit a Motec shortly. The Link has been capable of doing everything to get to this level quite satisfactorily.

ozzy

Click for Page 3

Stefan

harvey

iTrader: (48)

Thanks Andy...and Stefan.

bighead

iTrader: (1)

THANKS guys for the info.

bighead

iTrader: (1)

..

nom

You want more?

myp1

re the aps this is my old car and bob did a tek 3 remap for me on it so fuelling is ok at present..on wot the afr gge is at max richness..re gauges bigheads dash is like a fighter pilots i monitored afr/knock/oil press/oil temp/water temp/boost/egt/fuel press.i have told him its a trade off bigger turbo gives more lag.if i was going the route again i wld have different air filter to remove lean spots and a smaller turbo as my driving was all under 100mph more of a buzz 0-100 never intended the car for the strip or track its a tricky thing getting a turbo that will pull like a train low down but not run out of puff higher up...mike i dread to think of how much stick u are giving my best ever creation(SOLD DUE TO THIEVES BREAKING IN MY HOUSE TO STEAL IT)NOT THAT I AM AT ALL BITTER AND TWISTED ABOUT IT

bighead

iTrader: (1)

Hi paul,
still looking after your car ( or trying to....obviousely not as good as you lol).

It just that I find it a bit lagging lower down the rev range and would like more drive-ability .....as the top end is more than enough for me at the moment !

ps recieve the strutebrace from Spec-R thanks
the car is a credit to you Paul.......thank again
all the best ...mike

Bob Rawle

I remember this car v well, turbo is MD 304, v quick but ... bigger turbo more lag. the APS CAK was "interesting" at the time due to its affect on the maf.

bob

john banks

I switched from an MD304 to a TD05, got similar top end results on both, but the TD05 does spool up earlier and quicker, the effect in lower gears in particular is useful, whereas it is only about 200 RPM in 5th gear it is enough to make a real world difference. I found the TD05/06 20G has similar lag to MD304 but with a fair bit more power potential. TD05 with Gruppe S manifold I would say is simlar to MD304 without for spool up, and then it does easily make at least the same power at the same boost level. The MD304 may have a slight edge on power at 1.2 bar with the same manifolds used, but lost power for me going higher, whereas the TD05 continued to gain, although without manifolds needs higher octane fuel or water injection. Both need FMIC to give their best.

I think it is the turbine on the TD05 which allows the power and spool up advantages (the latter despite being larger, it has a smaller AR turbine housing), as the MD304 compressor should be very capable if it went with a capable hotside.

Horses for courses as always. Try and get a go in a well setup car with a TD05 with a similar spec to yours otherwise.

bighead

iTrader: (1)

Hi bob/john,
is it possible to bring the power lower down with a remap?
or would a different ecu management help (gems/motec/link) ?
or by changing the turbo ?
or by changing the APS CAK (heard bad comment on these)
or in a nutshell,
What is the best way to bring the power down without losing to much high up.

cheers .....Mike

nom

Bigger engine?
Nitrous...
Most other things are going to be a compromise - bringing boost in lower is done, basically, by having a more restrictive turbo hot-side, which is obviously going to screw up the top end.
I wonder why you want the boost threshold to be lower? Or rather make sure that this is what you really want? If you're looking for low-down driveability, you can get this with a later-spooling turbo anyway as the reduction in back-pressure makes the car far more driveable off-boost. Lag is more difficult to live with though
The APS CAK is a very good bit of kit, but needs to be used in the right situation, ie at the same time as a remap - it cannot be used safely without the MAF (if used) specifically calibrated to it.
The ECU is going to make no difference to the spool-point, but how that particular ECU is set up will.
Erm... I've run out of ideas

bighead

iTrader: (1)

thanks Nom,
for your time and thought.
probaly nothing wrong with the set-up at the mom.........it just that I used to ride big sportbikes( fireblade,R1 etc etc) and having got used to the power of the car now it seems abit " slow"

greasemonkey

Maybe more a case of adjusting to your new surroundings? World Rally Car would probably feel slow compared with a powerful bike

Bob Rawle

You can't take the APS CAK off because the ecu has special maf scaling in it to accomodate this. In any case that would not make any difference, larger turbo's inherently spool more slowly, even with the P18 back end. You must change your driving style in any case when driving a JDM spec car as they all have bigger turbo's than the equiv. UK (least MY97 onwards. You need to be at or around 3500 rpm to execute manouvers, then you will be suprised at the response, also do not snap open the throttle but rather roll it in, not slowly but briskly, again you will be suprised at the difference that makes.

nom

Why does it make the difference with 'rolling' the throttle rather than snapping it? The difference is phenomenal... never really worked out why! Well, there's a brief lack of fuel (presumably) irrespective of how much transient fuel is added, but is that it?

Bob Rawle

It relates to how you feed the built up boost pressure in the intercooler into the engine, when cruising off boost you actually make boost in the intercooler but not the manifold, if you snap the throttle you lose it all in an instant, roll it on and you feed it in which increases exhaust gas velocity which assists spool etc etc so the effect is significant. On the STi5, at 0.5 bar I get 1.6 bar in the intercooler, at vac I can see about 0.7 bar. Different for differing setups but you see what I mean.

The "sweet spot" is around 3500 rpm, if you hold there for a few seconds and then accellerate you will get improved pick up especially in third or fourth.

cheers

bob

nom

Aha.
I see.
I think
Thanks!

bighead

iTrader: (1)

thanks for the info Bob.

john banks

Bob, you know what I am like, I am going to express another view here to stimulate debate and in a genuine attempt to learn more....

I don't experience this phenomenon of rolling on the throttle, but I keep the throttle response as linear as possible so I don't have a load of boost in the intercooler (I use the weakest DV I can that stops the thing leaking on full throttle), with only large throttle openings giving full boost, just my preference as to how I like the car to drive having tried the strong dump valve, give it all you can as often as you can unless you get compressor surge method and not liking it.

In running high part throttle wastegate solenoid duty cycles with a strongly sprung dump valve to run say a bar across the throttle plate, are you forcing the intercooler to work harder by running the turbo far harder than you need to? Why do work fighting the throttle body restriction when you could open the wastegate on part throttle and use lower boost so that the intercooler has time to cool off? Particularly since the area of the compressor map used on part throttle could be the top left where efficiency is sometimes dubious. At the sort of boost levels some of us run, charge temperature even with a FMIC could become an issue again? TVR use long travel gas pedals with very linear response as their means of traction control, why make it non-linear and compress the action into a smaller range of the throttle travel? Turbo cars can be on-off already, why make it worse? If you really need the lack of lag that a fast spinning turbo has on part throttle, is the turbo too big and running too much boost to be driveable? Is this why a V8 twin turbo running 8 PSI for example is so satisfying - because you don't notice the turbo and don't need the non-linearity to work around lag issues? Does much over 1.5 bar make a very sensible road engine when you consider the lag involved?

I've perhaps missed an efficiency benefit in having the turbo spinning more quickly on part throttle, but why not make the car behave as NA as possible? After the initial fun of a turbo engine, a NA engine of similar power/torque I find more satisfying. Perhaps supercharging would be a better solution with a lightweight 3 litre engine. Perhaps I am nearly 30 and now believing in cubes rather than boost? Don't know where that leaves you Bob - my neighbour said he thought I was a bit old for a Scooby now LOL Not saying you are old BTW Everyone knows that the fastest Scoobies are all owned by people over 30 - Harvey, Andy, Bob, Mark LOL. Dave Wallis and Adam better grow old quick

[Edited by john banks - 9/9/2003 8:30:40 PM]

Bob Rawle

Rolling on the throttle is not about trying to drive with low boost but about getting the best response from the engine, good part throttle response is an essential part of the driving experience. If you want low boost its my view you just use less throttle.

bob