what boost?

just wondering has anybody got any information or experience with 1:8.5 compression pistons in a 20v and what boost to run.my engine spec is 20v agu with hybrid k04 and im wondering do i have to run more boost to compensate for lower engine compression.thanx

 

not a simple answer of what boost your engine will take.. far to many variables.
you should be able to run more ignition advance with the lower Cr...

std ecu? mapped? standalone?

 

Im using DTA.My problem is i live in the south of ireland and i just got the my 20vt corrado maped.the man who did it for me is a very experienced engine builder/tuner but he is not fimilar with my engine and had never used DTA.the car made 225bhp and 300ft/lbs @ 1.2bar not what i was expecting to say the least.i want abot 280bhp and i believe my engine is capable of this thats why i was just wondering about the boost with low compression pistons.

 

if its got 300lbft its clearly running high boost. you sure its only 1.2bar?
got a dyno plot to show its power delivery across the rev range?

 

a stock K04 will run 1.5bar dropping to 1.3bar at redline (7k). Then its a case of sorting the timing/fueling to suit your CR.

As Bill said, 300ftlb from 1.2bar sounds high.

 

sorry lads just lookin at the dyno plot it made 287.8ft/lbs @1.3bar.the man who maped it was not happy to run the boost any higher nothing to do with the car just he maps very safe.im just trying to figure out why iv loads of torque and little bhp.I really
apprichate the help.thanx

 

i am guessing there's a boost spike in that mid range >1.3bar hence the high torque @ that low-mid rpm

 

nearly sure it peaks at 1.3bar.man who mapped it said he felt the turbo wasnt up to the job,he said it starts boosting hard early and couldnt supply enough boost at the top end to make any more bhp.even when he was finished he said he wasnt fully happy with the map he said there could be more in it but thats as far as he was willing to take it and he really does not like DTA

 

Like i said before, stock K04 will take more as a spike, but cant really do more than 1.2-1.3 at 7k.

Not sure how the DTA works as i havent had any experience with it. I assume it has no knock control, maybe due to your nice lower CR, there is plenty of ignition advance as it comes on boost giving you that healthy torque. Perhaps there is more to be had top end (power).

I expect if it has no knock control, the tuner doesnt want to push the timing too hard so that you dont end up with holes in pistons. But a stock K04 with good exhaust should be capable of 270bhp with the right intercooler as well.

 

id like to have it peak at 1.6 and hold 1.3 as its a hybrid k04 it should be well able for that and also i have fitted forged pistons and steel rods the engine is sub 5k car it came out of was as good as brand new,it should be able for 300+bhp at least.no DTA does not have knock control it just does as its told.My exhaust is a 2.5in down pipe and rest is vr6 milltec.intercooler is custom front mount which works very well.tuner said he was very happy with intake temps on the rollers.

 

Above graph typical of 1.8T engines with small KKK turbos. The engine simply catches up with turbo CFM so your flow ratio dimineshes as would your torque. Other factors to consider too such as cams. For 300BHP you would need more "huff" come later rpm.
Unfortunatly VW/Audi never sized that turbo to produce large quanties of air at high rpm.
Unless you choose a suitable turbocharger eg a GT2871R, amongst other things, you would find your targets to be fairly difficult to achieve.

 

i understand that.im not looking for 300bhp if a had safe 260 270ish id be happy which i think my setup should produce all day long.a standard s3 with a map makes around 250bhp.my corrado with better intake,exhaust and turbo only made 225 and im trying to figure out why.i really apprichate the input lads keep it coming thanx

 

300 is too much for a K04, hybrid or not. In all fairness the hybrids cant do much more than a stock turbo so dont set you sights too high on that. Sounds like 280bhp is well within reach with your setup. Your tuner has played very safe by the sound of things. Either tell him to push your setup to its safe limit, or find a tuner who has a bit more experience with these engines/turbos/management.

 

ya thats kinda what i was thinking problem is to try a different tuner its a journey to england

 

where are you then? what country?

 

West of Ireland,Galway.I know its not that far from england but its still a nice drive in a car im not the confident in yet.

 

Should have guessed by the reg plate on the RR print out

 

mines 225 bam an i run 1.6bar on full boost with 301lbf/ft an it won't drop below 1.5, on cold nights it will hold 1.6...

 

what car,management,milage? what sorta bhp you getting and how long have you been running it like this??????

 

The little K04 will be suffering big time at that sort of boost!! what EGT's do you run on a 4th gear pull to redline? i bet they are skyhigh. If its BAM and you are running stock management you should be able to log/view EGTs in Vagcom.

You can almost run whatever boost you want. But there is a safe limit. As the K04 hates high EGT's, my personally professional opinion would be to get it mapped by somebody with experience of these engines. Make sure they use EGT and Wideband lambda gauges on it when mapping, then they can map your setup to run at its max safe limit.

IME, the K04 wont last long if the EGT's after the turbo exceed 900-950 for long periods.