Henrik

iTrader: (5)

Ok, so it's Monday morning and I'm having a **** day at work, but I'm feeling really disheartened by the car at the moment... It just doesn't feel fun to drive any more.

The engine mods are as follows (on a 2003 UK WRX):

TD05-20g (Andy F)
Autobahn88 fmic
apexi intake
ecutek remap
gt spec headers
ppp sports cat + decat centre
sti pinks (505 cc)

The above resulted in 353bhp/335lbft, which are not spectacular figures, but they're OK..

Now, the problem is this: It's just no fun to drive! When the power comes in it's really fast, but this doesn't happen until say 3900 rpm, and it feels really gutless below this. The mods have only been on for about 1500 miles, but i just can't live with the late spool and lack of low down power any more, I think!

What could I do to get some more low down power? The cost would mainly have to be financed by selling off parts from the list above (I can add a little, but I don't want to spend a lot of money).

Should I ditch the turbo and get a andy f td04 hybrid instead? I like the sound of spool from 2k rpm...

How about ditching the FMIC and going STI top mount?

To add to the woes, I'm getting a slight clutch slip now as well *argh*

SSCJAY

Start saving and get a 2.5l Bottom end, for the power your at now a standard EJ257 will do the job and will set you back £1200-£1500. That way you can take the engine out and change the clutch at the same time

I've just changed from 2.0 to 2.5 has has brought my spool down from 1bar @ 4200 rpm, to 1 bar @ 3200 rpm. Difference is fantastic.

Henrik

iTrader: (5)

How does your box cope with the 2.5 bottom end?

One thing I've wondered is if then new (2.5) WRX has a new gearbox or not? If it is new and uprated, maybe it would be a viable option to swap to once the box goes (as it inevitably will, with my luck)

The Hoff

iTrader: (5)

Your headers and FMIC are killing your spool. Go back to a set of ported OEM headers and it will feel like a new car (but you will loose out a bit on the top end figure)

The Hoff

iTrader: (5)

......and maybe try an 18G instead of a 20G

SSCJAY

I'm at the final stages of running in, and 1 bar is the limit at the moment, so no real stress on the Gearbox, Will be mapped soon then will just be a matter of time before the inevitable. Have heard the 754 gearboxes will handle 350-400 lb ft of torque if you show it some respect. But there are others that have found them breaking with less.

Mother Theresa

I have so been where you are. I know your pain and I too was in the doldrums about it all. I have swapped the 20g for an 18g and just changed back from an FMIC to TMIC. Only ever had ported headers so no advice on that one. I still have a CAIK and think that it is taking 2-400rpm off the spool but to be fair it does allow it to breathe much better over 5500 revs so will probably stay on. Someone will buy your 20g so you won't lose much.

I feel slightly better that I wasn't the only one so thanks for that. Headline power figures are not all they're cracked up to be. PM me for other thoughts if you wish.

WRX_Rich

iTrader: (5)

how fast can you wallet take you

im at a simular stage to you but with a bigger turbo with my std internal bugeye wrx

sad fact is you have a very fast car for the money you have spent the next 50 bhp is going to cost allot of money

i have gone the stupid route and already got the ppg box and im waiting for my rcm engine - i did want to buy a STI ppp but after a test drive couldn't part with the cash for what was a slower\ less fun car

im not sure what you have done with regards coilovers but this year i swapped the std dampers for a set of extc coilovers and that does make a very worthwhile difference at your level

my advice is go for a test drive in a STI and see how you get on

borat52

A FMIC should not have a large effect on spool at all. If it does then its most likely leaking boost. FMIC's add a little bit of lag, ie when going from no pedal to full accelerator it takes a time to build up pressure in the enlarged volume between the turbo and engine.

With spool its more a case of how much air the engine is consuming and not how much volume there is before the engine. A turbo wont make much pressure at low RPM because it simply cant push hard enough, not because there is too much volume to fill.

Any spool problems which are as a result of a FMIC should point to an air leak somewhere in my opinion. Lag is another kettle of fish.

The rookie

iTrader: (1)

I agree, while an FMIC increases LAG, it has no effect on the Spool rpm, although in lower gears when the engine is accelerating quite fast it has an apparnet effect (the lag means the rpm at which boost arrives is higher as the engine has accelerated, so for example boost may arrive at 4,000 in first, but 3,500 in fifth), having said that I think with your 'laggy' combo of big 20g, enlarged header volume and larger pressurised intake volume your killing the fun aspect...

Simon

andythejock01wrx

I have an Andy F TD04 hybrid. Only 301bhp, but with it's low spool (1 bar at 2500 revs, 1.4 at 2700) it feels a good bit faster than the figures suggest. Matt Patt got 313bhp on a Hybrid two weeks ago, and one bloke claimed 328bhp on a RR (although it depends which RR you use !).

A good compromise giving good power (330bhp+) and decent spool (3kish) would be a VF35.

HTH,

Andy Mc

Henrik

iTrader: (5)

Thanks for the comments, guys.

Still not sure what to do... part of me wants to drive the car into a lake and get a clio trophy and another part wants to modify it further


Andythejock01wrx: You wouldn't happen to have a power graph, would you? I'm still quite interested in the td04h.

I suppose I could try a vf34/35 (especially as they're only about 250 used by the looks of it), but I'm not sure how I'd like the spool on it. Especially considering I'm using a FMIC which apparently doesn't play too well with a VF34/35 (surge problems)


Mother Theresa: I actually originally bought the 20g as I thought I was going to go down the 2.5 route, but since then unfortunately my funding has dried up slightly How much did you get for your 20g? Mine was a brand new unit, but I doubt that makes a lot of difference to the price to be honest


SSCJAY: Mind me asking where you got your block from? The best price I seem to be able to find is about 1600 quid + fitting (also, did you modify your head combustion chambers at all)?


Perhaps my best option is to save up some money for a 2.5 lump, or alternatively rebuild my 2.0 so it can take a higher rev limit (probably wont matter much for spool and lag, but at least that way the power band will be wider, hopefully).

The obvious problems I can see with a 2.5 is a) insurance, and b) i'd probably need a ppg gear set which will set me back at least 3k fitted... 5-6k is a lot of money to spend on a car that isn't even worth that much (and it would break 10k in total spend on mods in that case which is just outrageous)

Alternatively, td04h with sti tmic and ported headers. I can probably do this for around 1000 including mapping, I'd say. Selling of my fmic, 20g and headers would offset this somewhat.

SSCJAY

I got Mine Built by Rallispec America, they can supply a basic EJ257 for $2000, depending how lucky you are with the shipping and VAT, will determine the final cost, but deffinately not more than £1400. Other costs ARP's £130 Head Gaskets £70
I carried out all the work myself so was a no brainer for me.

The Heads were not matched, I was advised to do this if I was going for serious power 500-600hp, although not ideal the 2.0l head, 2.5l block combination works very well as i'm sure lots of people will agree.

Am sure if you detuned slightly from your current setup (to save gearbox), the 2.5 would give a faster car as the earlier spool and extra torque does make a huge difference

Henrik

iTrader: (5)

Aha, that's not actually too bad at all... I'm gonna start saving up for a 2.5 block and an engine hoist in that case

The car's not boring because it's slow, but it's just that it feels really gutless at low revs which annoys me... it requires too much effort to drive (essentially I'm too lazy for this set-up). I want to be able to sit at 2500 revs in third and boot it, not drop it down to 2nd and wait and wait and wait until *bam* the revs climb past 4000 and then frantically change to 3rd before i hit the limiter and so on

Btw, that's a very nice setup you have there!

Mother Theresa

I got £650 for the 20g - only did a few hundred miles with it but I knew it was a mistake on a 2.0 WRX.

New_scooby_04

iTrader: (4)

Sounds like you've just got the wrong turbo there mate. Andy would have had to map that one very conservatively to protect your, presumably standard, gearbox and engine internals as that turbo is good for 380+ when tuned to its potential.

I'd go with a VF35 and a very real world usable 330ish bhp with similar torque. Nice compromise for a 2.0 non JDM Scooby.

ns04

mattpat

iTrader: (1)

I can confirm what Andy is saying.
The response from the TD04H combined with the tek3 map from Andy F is very impressive.
It really is outstanding the performance Andy gets from the little turbo
I only have a paper copy of the graph but will try to get it scanned in.

cheers
Matt

jasonius

iTrader: (1)

The one thing to remember with the WRX is the 5sp 'uk' ratios..!

Particularly 1st/2nd as they're significantly lower geared than the uk STI, more so than a JDM box..!

IMHO, if you go too big on the turbo it will kill the drivability low down, delaying turbo response until higher up the rev range. You then end up with a very narrow power band due to the 7k red line..!

Adding big bore tubular headers and FMIC just compounds the issue..!

VF35/ported oem headers an STI TMIC work extremely well on a WRX for fast road, regardless of peak figures..!

New_scooby_04

iTrader: (4)

Yep, exactly: the above gives you the kick in the pants when you boot it without the high boost threshold and resultant narrow power band etc...

Ns04

Henrik

iTrader: (5)

Hmm, i'm not sure I understand the gearbox issue... isn't the apparent power band for the same engine shorter with a 6sp if the gears are shorter? E.g. say you have 'enough' power from 4000 to 7000rpm - on a 5sp this will take you from 35 to 62mph, say, where as on a 6sp it would only take you up to the high 50's or am I missing something?

Seems I've made some bad choices with regards to the mods... As I mentioned earlier, the turbo was chosen with the plan to put a 2.5 in there eventually, and I think the other mods may work well with a 2.5 (bar the FMIC, maybe).

I'm going to have to spend some time re-thinking what I want out of the car - I'm sure a 20g on a 2.5 would be faster than a vf3x on a 2.0, but at what cost?

Do you guys think it's realistic to budget 2000 for a complete 2.5 solution using as many existing bits as possible (assuming I can get my mits on a 2.5 short block for around 1400). Incidentically, does anyone know how much a 2.5 WRX short block is (and how much power is it good for?)?

Slowboy Racing

The 20g is suited very well to the 2.5 or a 2lt with the internals that can cope with the boost that it needs to get the most from it however the results will be very different.

There is no point getting the 2.5 bottom end unless you plan on maxing out the 20g And if that is the case then a 2K budget wont do it as you already no with regards to the box and clutch and fitting etc it soon ads up. It also doesn’t make sense to spend 2k and gain a little toque around the 350 mark to compensate for what your current set up is lacking when you can get a smaller turbo for a snip of the cost and this will be addressed, after all its not about the figures as you no.

The best option would be a smaller turbo as said above Hybrid TDo4 works its magic very low down the RPM range Or the VF...

Failing that consider 2k + for the 2.5 and it would also be wise to consider aftermarket pistons if you do plan on the 400bhp area For long term reliability.

Henrik

iTrader: (5)

ah yes, the 2k was just a figure for the engine build, really (solution was probably the wrong word to use )... Must run the figures through SWMBO, which runs the risk of ending up with a 1.2 clio

Does the STI short block have forged rods or do they need to be changed as well? I'd love to avoid splitting the block because that just sounds like a whole load of hassle, but if it's just a set of drop in pistons that shouldn't be too bad

Aztec Performance Ltd

iTrader: (234)

they are forged rods good for upto 450 iirc

ClintUK

I have a similar spec to Andythejock ie hybrid TD04 and supporting mods. I'm not much down on your torque figure which is really where the 'fun' is for day to day driving.

I haven't been able to find a 'standard' power and torque graph and although your car is a lot newer than my 97UK car I'm sure there's relevance in this:



Also it was really noticable it's now easier to drive round town at low revs etc, due to the better low end torque.

I have
OEM flowed headers & up pipe
Miltek sports cat & system
Apexi ECU (ECU Tek n/a on my car)
Hybrid TD04
3.5Bar fuel pressure
Original top mount

Apart from the extra torque & power though, I've really enjoyed the benefit of suspension mods, stiffer ARBs front and rear, ALK, castor bolts & Whiteline geometry.

Better brakes for me were a must too, it was fun showing them off to a couple of friends, but it's just rude to do that to most people

jasonius

iTrader: (1)

Basically a big turbo needs more RPM before it produces any real boost/performance (eg 1bar at 3500-4000rpm compared to a td04/vf35 1bar ~2800) but will keep going well beyond 7k..!

Therefore with a uk 5sp/big turbo combo you can find that, for example slow corners at around 20-30mph your stuck between gears. 2nd will equate to around 2.5-3k iirc leaving you waiting for the boost to start building (for another 1000rpm..!) or going down to 1st, not ideal either way really..!

Now same situation in a 6sp, the rpm would be more like 3300-3800 (2nd) which is at or a lot closer to the turbo's boost threshold, even higher with JDM ratio's..

The higher redline of STI engines also exploits a bigger turbo better for the same reason, helping to offset any extra gear changes needed..

Assuming you have a boost gauge, go out with a fully warmed up exhaust/turbo and try planting you foot on the gas in fourth from about 2k and note where in the rev range you make 1bar of boost..

WRX_Rich

iTrader: (5)

before dropping down to a vf35 i still think you should go for a test drive in a STI PPP as said i wanted to swap but knew as soon as i drove the STI i would end up changing the turbo

went out in mine again last night and still find it easy enough to drive around the lag but thats me and my car is for fun and fun only and gets driven as such it hasn't done the shopping run for years

imho a 2.5 is the way to go ( like you have always planned) as the vf35 will feel slow in comparsion

Rich

jasonius

iTrader: (1)

^^^

Rich, what turbo are you currently running..?

Northern Nick

iTrader: (1)

Garrett (RCM) GT35/P18