Hi

Ive got a 2.5ltre Hawkeye STI and i believe it has a VF43 (stock turbo) that is currently mapped to around 340/340 at 1.1/1.2 bar...(ecutek)
currently fitted is the 3'' exhaust (miltek) with a high flow sports cat , panel filter and fuel pump.
Should I get rid of my sports cat if i want more power? does a 100cell sports cat make much difference on the power or isit not noticeable?


I want more power and seek advice on options and opinions, I want a fast street use car, im not looking to do track days at the moment but may consider them in the future

whats the maximum boost pressure i can run on this turbo on my stock internals?
what kind of torque figure would i see?
how reliable would it be?

I have also been researching into Andy Forests Td05 turbos. My G/F has a Blob fitted with a AF TD05 18G mapped to 1.5 Bar with all the supporting mods and when it comes on boost the feeling is great however being the 2ltre block it does take a little bit of time to quick in , i believe it makes full boost by 3700 revs

Now on the 2.5 block how much lag would there be with a bigger turbo like the 20g?

Now I do have the option of saving up for a 20g turbo and getting that mapped on a ECUtek by JGM but what kind of power figures can i expect both bhp and torque and what boost pressure could i flow through the turbo to expect them figures?..Im also looking to stay on stock internals

I understand that this may have been covered many a time, but i cant find any threads where people have had posted up there dyno graphs or advice for 18g/20g turbos on 2.5 litre blocks

I have considered a Simtec ECU but it is quite costly and would prefer to stay with ECUtek....have many people switched from ECUtek to Simtec, if so what are your experiences? is it actually worth it?

sorry for all my q's but as you can tell i am a newbie
all help would be much appreciated

 

Go for the 20g . I've got 18g on my set up and it's ok but power drops off after 5k(just can't keep up) .The 20g is a much better suited turbo to the 2.5 and you Should see 380-400bhp with supporting mods i think .

 

Hmmmm, anybody got any graphs of a 20G on a 2.5 litre?

 

fit a lateral performance md321t/v on yr 2.5 and you will be more than happy
i had that on my 2.5 conversion , no lag at all 450+bhp /450lbs/ft torque
not cheap but best turbo for standard pos fitting without going rotate

ps........... you will find the 20g a bit small on a 2.5

 

Internals are at risk running above 400 (mainly pistons).
The turbo I would suggest is either MD321H or MD321S both fantastic turbo's.

I would orecommend the MD321T/V only if you've swapped rods and pistons or you can honestly say you wouldn't run in excess of say 420bhp max.

 

Is that right..... I would strogly argue against that!

 

Remember I was there that day too Shaun

545bhp from an MD321V versus your 498.5bhp if I remember rightly

 

tbh i want to get near the 390/400bhp mark but i want max torque than anything

nobody rate the Af td05 - 20g then? why would it be too small?

also im not looking to touch the internals..unless i really have too

 

To answer the OP questions/points:

The std turbo is aVF43 - 340/340 is a very conservative tune. I had my std VF43 running at 1.5 bar peak tailing to 1.1 at redline (it just wouldnt hold any more than that) and it gave 360/410 on that. That is a very quick and useable level for the road.

Before considering going above what the std VF43 will deliver you have to consider the chances of it going pear-shaped. This can happen at any time but you are dramatically increasing the risk going above 400 bhp. Therefore without changing the pistons (ie taking the engine out and dropping some forged pistons in) you are treading on thin ice. As you can imagine doing something like that is not going to be the cheapest thing. If you go above 400 bhp with the 2.5, the torque is higher so the std clutch will not survive. Mine was showing signs of struggling when I changed it to upgrade engine internals. You can therefore add another £800-£1000 to the upgrade cost.

If you think 'well i'll risk it' that is fine but dont cry when it breaks. But I would strongly suggest that you keep below 400 bhp and have a great road car. For what extra a 20G will do over the std turbo ... ie 20 bhp is it worth £1000-£1500 for that ? I'd say not.

If you do decide to go above 400bhp - it is expensive whatever, so you might as well go for high 400's There are a few turbos that are worth considering for that. I chose the MD321V and it hits 490/490 and 545/545 (on a e85 enhanced fuel)just bolted onto a 2.5 sti engine with standard UK heads and cams. Shaun's hit 498 bolted onto a 2.5 STi engine with £3000 + of cosworth heads and cams so may not be repeatable on a car that doesnt have those. If it was repeatable then I would be asking for my £3k back from Cosworth if I were him

Oh and by the way - you cannot get a Simtek for the drive by wire subaru. They were talking about it early this year when I was looking to change mine but they still havent got their fingers out and built the thing. I have kept with the std ecu and it is working just fine up to 550 bhp thank you with launch control and flat throttle shifting.

 

I've recently added a TD05/20g to my 06 2.5 STi, mapped to 1.45 bar by Zen Performance.
The bottom end is still standard.
Click on <<Plus Profile>> to see further info.

It replaced my ported VF43, but has equally good spool up (1 bar @ 2700 rpm, 1.45 bar @ 3000 rpm).
The chassis now feels loaded all the time - the VF43 would spool up so quickly that the torque loading would upset the car.

Also found that the VF43 had started to develop a crack between the wastegate/turbine area, so just as well I caught it early.

When there is time, I'll road dyno (Ecutek) the car to compare graphs obtained on the VF43.

Swapping to the 20g will need extra fuelling. I added an FPR, but new injectors would also fit the bill.
I'm running a dcat, but a decent sports cat wouldn't loose too much.
BTW, i have a newage 3" Hayward and Scott sports cat available.


EDIT - I'd disagree with Duncan, the smoothed out torque delivery and the extension of power to the redline makes this swap worthwhile.

nick

 

daz,
If I had pee'd in the tank like Duncan did, I would of beat him..... he knows it, I know it! So.... I would still argue with the original statement!

Duncan,
As regards to heads...... this is how I see it:

Opening up the ports should in theory hammer my response and lowdown grunt (giving less torque), in favour of enabling the engine to shift more air further up where it is needed. Did not seem to hammer my torque though did it.

The standard heads CAN flow enough air for over 500bhp.... we all know that, as people like you have proven. In theory then, it would be totally acceptable to suggest that the peak power may not be anything different....... but as already discussed on previous threads, this can perhaps be achieved at less boost with the Cossie heads.

I plan to run 2bar flat decked (which will be comparable to your E85 boost) on VPower.... let's see how the power goes from the last Zen run, compared to your E85 run, whilst I am still crippled on VPower.

 

some good info on her for the standard 2.5 boys....2 of the best op on here telling you what to do is a good thing as both othem have had alot of experience of them.

 

Shaun - I am confused.

£3000 + of heads and cams that will:

a) reduce torque thereby reducing power low and mid range
b) not produce any more power up top

Good purchase Cosworth must have done a cracking sales job.

Your 498.5 on vpower with heads/cams at 1.95 bar (in 5th gear) compared to my 490 on vpower tailed to 1.7 bar with std heads/cams in 3rd gear. This still doesnt add up to me. Either the heads/cams you have are worth 8 bhp (£400 per 1 bhp) and the turbos are equal (being generous and leaving aside the fact that your run was in 5th versus my 3rd gear) or the heads/cams are worth more than 8 bhp and the turbo is worse. You cant in your right mind possibly believe that the heads and cams are costing you power ????

 

Duncan,
The turbo will blow what it will blow...... how can heads make more power, unless you need that extra flow capacity because the turbo can outflow the heads?! You have proved that the standard heads will flow enough for 500+bhp.

Opening up the ports should in theory, slow down spool and decrease torque as a consequence.

So.... am I benefiting from my heads and cams at this level? I honestly don't know. It would need someone more technical than me to comment on that, as we are only looking at specifics. Unless I ran without the heads/cams on the same turbo and map, it is impossible to say.

My car does what it does and I won't be chopping my heads in!

 

Shaun, this just doesn't make sense to me. If you open up the ports, surely you increase the speed with which the engine can fill with fresh air and pump out the exhaust gases, thereby improving spool?

 

Guy's - what's all this big power ***** waving got to do with the OPs question?

 

I've answered his questions

Just amusing ourselves whilst waiting on a response

 

LOL

Perhaps a new thread section is needed for owners of more than (or just a little bit under) 500 hp is needed to thrash out who has the larger gonads.

 

PMSL

 

STIFreak,
Opening up the ports will normally DECREASE gas speed. Don't confuse speed with volume. Back in the Cossie days I was always advised NOT to go for a major GRP A spec port on my RS500, since it would mean less response and less torque. Instead I did as I was told and went for a mild port..... the result was greater torque lowdown.

lol @ Duncan

To everyone else - This is how we ALL learn. Perhaps Duncan and I should shut up and only speak off-line to each other. Then you can all make the mistakes!

 

lol.....it gives us all something whilst our car is off the road for so engine work

 

I'm happy to learn from someone who has owned a std 2.5 car and has gone through the power range that is part of the OPs question, but this thread went off at a tangent and we were in the realms of mega builds.

There's several ongoing entertaining threads on SN and 22B that I can sit down with some popcorn and be amazed what you have accomplished, but this thread isn't the place.

nick

 

Butty - I am sorry but I think you are wrong.

The OP is starting on the same journey I went through on a std UK Sti but is looking at turbo change too early IMO. There is plenty left in the std turbo before changing. As I answered above you can get around 370bhp and over 400 lb/ft from the std turbo on a 2.5. That level of power made for a really great road car, just enough power to use and no 'issues'.

Going above that level requires a LOT of investment.

If changing to a 20G then the cost of the turbo will be a waste in my opinion as you will only get another 20bhp for it. Is that worth it?

If it isnt worth it, then going above that level will require investing in, pistons, clutch, probably a fmic, injectors, fuel pump, fpr, induction kit mapping etc etc. This is many thousands of pounds. Again is it worth it for the road?

Why the obsession with the power for use on the road?

Mine and Shaun's are both used in anger where power/torque help shave time off a lap or 1/4 mile which is why we took the expensive steps of going over that level. Once you take that big step, you might as well do it properly.

The OP also asked about ECU change. SImtek doesnt do a DBW system and in my opinion it is not needed anyway. I still run the std ECU and MAF.

 

Dynamix you have PM

Obsession for fast road car is the grin it puts on my face when i apply the throttle (just like eveybody else)
As said i wont be doing track days for now but want a car that will scare the s*** outta me when i drive it hard

If the standard turbo can produce high figures like 380/420 then i will stay with the stock turbo as what you have said is true - It would be pointless buying the 20g if it just made extra 20bhp when the standard turbo can produce near enough the same power

one thing tho should i remove my sports cat and get a full decat? or stay with the sports cat? (assuming im running 380/420)

Thanks guys for your responses, I understand it may have been covered numerous times, but i am new and havent seen many tweaked newage 2.5 sti's

saq

 

A good 100 cell sport cat is fine, but it will cost. In the same breath, a decat will unleash the full potential, be cheaper, but will give you gas come MOT time.

 

hi all you all seem to know your stuff on tunning , i am looking to fit larger injectors to my 94 sti she is running at 340 bhp what sort of power gains wil i get from doing this and what else wil i need to change? fuel pump ,fuel rail , or wil i need to fit fuel pressure control im not sure which way to go about it , would be greatfull for some advise , i dont want to go above 400hbp as only road car and its plenty as it is but you all know how it is you always want that little bit more!

 

thought this was a turbo question thread last time i checked the title



anyway, who mapped your car and what boost pressure are you running at the mo might save you mentioning it later if someone else asks

 

Fair enough Duncan.
All I can say is that what I didn't enjoy about my Vf43 @ 1.3 bar was the charge temps in summer and the drop off in power after about 5.5k revs.
These were only a concern due to the mileage and high motorway miles ( & sustained speeds) the car puts in.
Mileage and how the car gets used may not be issues to Juicep1.

Another factor was that swapping to the 20g with mapping cost me £800. If I had paid full wack for everything then I may have thought again.

The swap to a 20g has shown up two unexpected issues - the quick spool up of the VF43 unsettled the car. I didn't realise how much until the 20g swap, but this may just be a factor on my driving style.
The 20g has made the chassis constantly "taut" compared with the VF43. I would appreciate a more technical understanding of what this is due to?

The second is that I found the VF43 had started to develop a crack on the hot side. Whether this would have developed on the standard output or was due to tweaking I can't say, but it is a noted issues in the US.
If the cracking develops with mileage then I would be experiencing its full impact on boost control earlier than most if the VF43 had been left on.

Nick

 

You had ported the exhaust housing on yours iirc - maybe that contributed.

Charge temps were never a factor on my VF43 as I had spent a lot of time sorting the cold air route into the airbox (and beyond). Certainly never a huge issue until a substantial amount of time was spent on track.

 

Yup it was ported.
At the time I did the porting, I thought the web between turbine and wastegate looked thinner than the VF35 I'd ported before and so left that area alone - but it has still cracked.
I had to port it as I was getting boost creep that cause several issues - I'm surprised it didn't happen on yours?

nick