Boost pressure for built engine

[killboy]

Originally Posted by ChrisD

What's making you want to go external wastegate (if you weren't having the problems with the AVO one) ? Funnily enough I did have an issue with the wastegate on my AVO turbo too... hasn't quite been resolved yet so I'm not sure exactly what the problem is.

As Matt said, better flow for high HP, plus ext. type use a faster reacting "plunger" style valve that can vent off pressure more rapidly than the flapper door inside the turbo. Therefore the tuner can set it up to build boost harder/quicker/longer and stop it with immediacy, rather than having to start opening the wastegate before max boost is reached due to the latency of internal flapper door response time.

[Andew727]

Originally Posted by ChrisD

I swear I've seen quite a few threads on this but now that I'm searching for them I can't find much... so hopefully someone can help me out here.

Basically at the moment I've got an AVO stage 3 turbo running 0.6 bar (about 8 psi) on the low boost map and 0.8 bar (about 12 psi) on the higher boost map, but this is on the stock engine.

I'm considering getting the engine built with forged rods, lower compression ratio pistons (10:1), and stronger valve springs, so that we can then increase the boost without too much risk of damaging anything. But I'm wondering what sort of level it would be "safe" to increase it to. I won't be running it on E85 or race fuel, just 98 RON super unleaded petrol.

So does anyone have any experience with (or know someone who has) a boosted FA20 that has had forged internals installed, and if so what kind of boost pressure were they running and did it end badly or is it still going strong?

If I can only really get away with increasing it to 1 bar or something then I probably won't bother, as the difference between 0.6 and 0.8 isn't that noticeable, so I'd need to be getting close to doubling the pressure for it to be worth the cost of the engine build for me really.


DISCLAIMER: Yes I know there is no 100% accurate answer because everyone's version of "safe" or "reliable" is different. I'm not expecting the engine to last forever, but I drive the car a lot and do plenty of track days and drift days so I don't want it to be running so much boost that it might blow up after 3000 miles. Again I know no one can guarantee that won't happen even with relatively low boost, but I'm just asking for a general opinion of what is sensible and should be fairly safe on a built engine.

you can lower compression a little with larger head gaskets. cheaper than replacing pistons. there is a lot less chance of detonation with e85 making boost safer then. if you dont run e85 then dont push high boost on stock heads and lower unit.

valve springs are pretty cheap and relatively simple to change out. as for rods, i found that skunk2 makes H beams for less than $400 for the set. i picked up a set of those while i had my engine out.

hope that helps

[#maverick#]

Originally Posted by ChrisD

is that on E85 or normal unleaded?

E85 its good stuff. Honestly I would look into ordering 55 gallon drums of the stuff and run a flex fuel kit for hooning haha

[Matt@Cosworth]

these guys sell it
http://www.trackstuff.co.uk/VP%20E85%20Racing.htm

£4 a litre mind

and yes you can run a flex fuel sensor to accurately judge the amount of Ethanol in the fuel and then add spark appropriately via custom maps vs the flexfuel sensor output

its good stuff but pricey

[cdrazic93]

Originally Posted by Matt@Cosworth

you'd like to think so wouldn't you?
however deburring is a time consuming process that adds greatly to the cost of the part so they can't compete on price if they were to do this

still up to you, its your engine

This is what honing and balancing your engine is all about...correct? Im assuming when you have an engine built buy someone they deburr it.

[Matt@Cosworth]

Some builders may do this ....some may not......

you pay your money and takes your choice