It's not the power, it's the torque. The general recommendation is to not go higher than 300 ft lb. A K04 with TT 225 injectors will see you at 270-280bhp with similar torque figures. A load of bullsh*t flies around that you can get 300 on a K04, but the K04 won't flow enough air, even with a well flowed head. To get to 300, you'll either need a hybrid K04 or start looking at a Garrett etc, so you may as well rebuild the whole engine. The rods are the weak part. Standard pistons will take up to 400bhp, depending on who you talk to.
Even if you could achieve peak power of 300bhp on standard internals would you really want to? It wouldn't be too long before the stress on the engine bent something...
The heads on these flow quite well with stock cams as is evident by 300lbft achieved at mid revs with a 5304 unit. Turbo will start to run out of puff and nosedive torque post 5000 rpm. So measured peak tends to be around 280bhp or so. Still the rods will be at the limit. Stock rods are like butter on these engines as are exhaust valves.
cheers guys some useful info there i will probably run it at 250-260bhp then until i can get a forged build done, was planning on a gt28 turbo as they seem to give decent power a fast spool times.
heres what happend to one of my engines bam code running around 280bhp at the time same torque figure
what boost was you running?? and how did that happen as the ones i have seen like that the engine has hydrauliced
Here in spain theres a 180hp leon, with a GT30 (over 350hp), now downgraded to a GT28rs (320hp) without a single problem. Its not a track car, just a highway rocket, suppose that helps.
I just don't get the "bolt on a bigger turbo and see what happens" mentality. Yes, I guess for a lot of people it comes down to money, but surely people can see that long term, it's going to cost a shed load more.
Similar effect happens when the t/belt snaps on them. Sub 2500rpm t/belt breakage resulted in... Making these... members with for scrap. As said the rods are like butter. Best to update if the engine is going to be serious. For the price Bill suggested, seems a small bit to pay.
There are lots of cars running low boost on large turbos well into the 300+BHP range but the torque is kept well below 300bhp or even when close it is very smooth in its delivery. 50trim, 28RS equipped cars on a decent MAP that "could" run a lot more power. It is not the torque figure per se, it is the delivery. Small turbos maxed out on boost and flow will deliver steep torque curves or even spikes depending on the MAP they are running. If you are running 280bhp on a KO4 I would be surpised if you have a nice smooth torque delivery regardless of the file...... torque going from 200-280ftlbs in the space of 500-1000rpm is a lot worse than a constant 300ftlbs over the same range for the cost of a set of 19mm rods and bearings on your stock pistons I don't see the point in risking 1000's in damage just to run that close to the edge. SCAT, IE, Eagle, Brute all sell forged rods that will take waaay more than you will ever need. Your stock pistons are forged Mahle units and have been tested to over 500bhp on lots of high revving big turbo applications. Your next problem comes when increasing your exhaust gas temps so high because your KO4 turbine housing is restrictive, reversion and exhaust gas temps through the roof and your exhaust valve heads will start to drop off at high revs FUBAR'ing your valve train, pistons, block wall, turbo and wallet.
I can get the rods at trade through work, but the problem comes when opening up the engine its always the same ......................oh ill just put in a new set of bearings, might as well do the rings, being as im in there the oil pump, then the valves, then port the head, oh by the way might as well get a bigger turbo. You guys know how it goes, ill end up spending 's maybe ill just run less power until money is a little more available.
This man is bang on! Most you'll get out of a Ko3's is going to be 230bhp MAX without a hybred (260-270 maybe?) Ko4 wil do no more that 280bhp with similat torque figures. after that you need a gt28rs or similar to break the 300bhp barrier. the turbo kit is big dolla so if your going to splash out to hit the magic 300bhp+ then whats an extra 500-1000 quid to build something thats reliable and lasts! change rods and exhaust valves at minimum and i'd recommend good valve springs wtc up the top end and prob pistons on the bottom as well! Speak to Alex @ Backdraught! he's running a built 450bhp Ibiza cupra atm - serious money!
its the quickest way of getting big power and everyone loves a bit of pubtalk about power figures. what would you have 300hp and a ticking time bomb or 250hp and run it everyday all day.
