Scooby build for reliable 400-450bhp

BentMetal · Post by **BentMetal** » Wed Dec 24, 2008 10:42 am

Guys,

I'm looking for some advice on my Scooby.

In a perfect world I would like to have my cake and eat it... err I mean get a motor built for my Scooby to run 400-450bhp while maintaining driveability and reliability. Is this possible or am I dreaming?

The engine will go in my STI V6 Wagon which will be used primarily for Ring trips and the occasional UK track day plus normal road use. It is not a daily driver but gets used on average twice a week to visit friends/family etc... with the track use on top.

If this is possible, I can't decide what route to go; 2.0 or 2.5 etc...

What's best in terms of achieving my aims and keeping costs under control? Would I better off retainig my block and using STI8 crank with forged rods and pistons etc... Or do I bin it and go the 2.5 route, again with forged rods/pistons???

I've put a 6 speed box in with a suitable clutch already and I'm running SimTec management. The bits I'm missing are a decent turbo and FMIC. And here lies another problem; what turbo should I be looking at? I have to say I don't keep up to date with all these turbo models and so it's a bit of a mine field for me. I would like to use the smallest possible turbo to achieve the power to maintain response.

Any advice will be greatly appreciated and apologies for the long post

duncan · Post by **duncan** » Wed Dec 24, 2008 10:50 am

Mine is still a daily driver even at around 550.

Done 11,000 on the engine that Area 52 Autosport built and has never missed a beat. That was part of the spec (and budget) though and I would not hesitate to recommend them for the build... however... do you really need 450 ?

400/400 can be done with a std 2.5 STi bottom end for very little money with the right turbo. Lots of choices turbo wise (std mount jobs):

for 380 ish - 20G
400 - 20G with methanol (prob not practical with ring trips)
400 - 420 MD321H
400 - 450 FP Green HTA
450 + I would have to say the MD321T or T+.

Even my biggest MD321V out-spooled smaller turbos and for response it is an advantage being ball bearing rather than sleeve bearing from what I have found.

BentMetal · Post by **BentMetal** » Wed Dec 24, 2008 11:13 am

Cheers Duncan for the reply.

I don't need 450bhp, but I certainly fancy it!!! To be honest, I think I would be happy with anything 400+. The car is currently around 320bhp.

What I want is for it to be faster than it is now and to be able to withstand some hard use while being fairly reliable.

From the research I've done, the turbos that keep cropping up are MD321H and the MD321T.

Would a stock 2.5 bottom end withstand a lot of hard use?

Cheers, Matt

Gerry H · Post by **Gerry H** » Wed Dec 24, 2008 11:59 am

I think I'm right in saying that Andy Forrest reckons the stock 2.5 is good for reliable 500. At 400+ you're really looking at twin plate or paddle clutches so hope your choice is good.

I'm not in Duncan's league but the FP Green I have has been great and a fair bit cheaper than the MDs. MDs crop up a lot because of aggressive marketing, but they are a good turbo

20g gave 375 ish and was super quick low down & mid range.

Faster depends on gearing and rev limit. Quicker depends on gearing and turbo.

2.5 is a world difference to the 2.0 with regards to low down grunt, the torque difference is amazing and the extra gasses help the turbo spool quicker. For a cheaper, instant, buzz, the 2.5 is the way to go.

Nice thing about the Subaru, despite silly power levels they're still very driveable on the road.

IMO

duncan · Post by **duncan** » Wed Dec 24, 2008 4:08 pm

Gerry is right, when you start going over 400, then the std clutch (even on the 6 speed) is past it's limit and it is into twin plate territory. => add a grand for that.

It would also need a FMIC = > add another grand for that too, plus induction kit, dump valve ...

injectors.. prob 740's would be needed

up to 450 can be done with std rods but I would change pistons for forged.

over 450 and forged rods would be adviseable, this and good bearings will give you the ability to raise the rev limit too.

That will take you over the 450 and it is just a turbo choice that dictates the final power.

The step from 400 to 450 is very expensive, but the step from 400 to 500+ is about the same.

Neil... · Post by **Neil...** » Wed Dec 24, 2008 4:48 pm

Gerry H wrote:I think I'm right in saying that Andy Forrest reckons the stock 2.5 is good for reliable 500. At 400+ you're really looking at twin plate or paddle clutches so hope your choice is good.

I'm not in Duncan's league but the FP Green I have has been great and a fair bit cheaper than the MDs. MDs crop up a lot because of aggressive marketing, but they are a good turbo

Stock 2.5 block good or 500...??

Last I heard was Andy F had ran upto that sort of figure, but with drop in pistons fitted, then when he removed the motor for a refresh, he found the rods to have stretched a bit...

As regards the MD range having aggresive marketing, I am pretty sure that all the MD praise/marketing has been purely from the end users..

Neil... · Post by **Neil...** » Wed Dec 24, 2008 4:50 pm

duncan wrote:
for 380 ish - 20G
400 - 20G with methanol (prob not practical with ring trips)
400 - 420 MD321H
400 - 450 FP Green HTA
450 + I would have to say the MD321T or T+.

Even my biggest MD321V out-spooled smaller turbos and for response it is an advantage being ball bearing rather than sleeve bearing from what I have found.

I wouldn't put the 321T as 450+ dunc, unless there is methanol/bio involved.

Really looking forward to my V though...

duncan · Post by **duncan** » Wed Dec 24, 2008 4:53 pm

True Neil - the T+ should do over 450 on std fuel I thought.

V+ is the one you want though

:lol: :lol: :lol: :lol: :lol:

BentMetal · Post by **BentMetal** » Wed Dec 24, 2008 8:47 pm

Clutch-wise I've already got a twin plate - I only fitted the 6 speed box and flywheel 2 weeks ago and I was already hatching a plan with regards the engine.

Can you give an indication of costs for the different options? For instance, how much approximately for a stock 2.5? How much for a 2.5 with a forged bottom end?

Duncan, when you say going from 400 to 450bhp is very expensive, is that purely referring to the forged pistons/rods?

My budget for the motor, not including FMIC, turbo etc... was

Gerry H · Post by **Gerry H** » Wed Dec 24, 2008 8:58 pm

Neil... wrote:
Stock 2.5 block good or 500...??

Last I heard was Andy F had ran upto that sort of figure, but with drop in pistons fitted, then when he removed the motor for a refresh, he found the rods to have stretched a bit...

As regards the MD range having aggresive marketing, I am pretty sure that all the MD praise/marketing has been purely from the end users..

Maybe the 500 claims on stock 2.5 have been revised since I saw the thread. It was just after I'd decided to go for a built engine and wondered whether I'd done the right thing. I feel a little happier with my decision now.

The aggressive marketing comment was not so much aimed at Lateral but more the persistence of the various tuners in slagging the FP range over the MD. Not too many punters, having shelled out ~