Need some advice as to the future of my GC8
 

Hello all,

I have recently bought a 1993 Subaru Impreza JDM Import 2.0 WRX and I am trying to understand it a bit more and its capabilities.
If I say anything that sounds wrong please correct me as I only know what I know and am trying to not sound like an idiot.

Current Specs:

• TD05 Turbo 16g
• 550cc pink injectors
• 244 Walbro Fuel Pump
• Ally race radiator
• Large Intercooler
• Ram Air Filter
• Decatted Straight Thru
• On standalone ECU APEXI with turbo timer
• Big Brakes
• Mapped by the Jolly Giant (Checked by Duncan at Surry RR) - 340BHP

Now I'm trying to get advice of the best way to keep the car healthy yet get the most out of it, I am on a budget but as time passes I will have more to put into it.

1. My first question is what do people think the internals are rated for? I currently am not sure whether going for 400 without forging is stupid, Forging is something I will consider in the future but not yet.
2. What other supporting mods do people suggest? Like I said forging is part of my future plan for it but uprated clutch kit? Higher pressure fuel pump? Uprated water pump? Ported Heads?
3. Turbos... Now I realise the TD05 is rated for 350 so I probably need to change it out, I also realise it has a fair amount of lag, What would people suggest as something not just for 400 but onwards, after its forged ect where I wont need to change again to aim for 500.
4. Finally, The heater coolant hose has cracked around the clip twice recently, I have got new hoses and coolant cap in post and im not driving it till they are on it, can anyone think of any other reasons why I keep getting a build up of pressure or do we think its just old hoses? (They look pretty solid so its baffling me)

Thanks people for putting up my lack of knowledge and thanks in advance for any help.
:)

1. I would say both engine and gearbox wouldnt cope with near 400bhp or the typical torque figures associated with that power. Most likely you are already pushing the limits of that engine and gearbox. So forged engine and, the easy option, 6 speed conversion.
2. Front mount IC? although some still run big top mounts, FMIC takes away all the negatives of TMIC, but adds alot of pipe work and maybe some lag.
3. Look at the SC42 onwards series or MD321H series there a T and V version of those
4. Just the age of the pipe work mines a version 5 sti and had the same heater hose problem this year, it split at the clamp and then a pin hole appeared weeks later, id go through all your coolant hoses just as a precaution if they are all original.

Hope that helps im sure others will come along with more opinions

Thank you this has been a huge help.
I didnt think about the 6 spd what would be a sensible conversion budget?

Yes already a fmic but i definitely am feeling the lag

I looked at the SC42 and 46 what are the considerations when comparing the two?

Yep, all hoses are being replaced this week with silicone ones just out of peace of mine, i am also changing the radiator cap as its £20 that rules another possibility out. thanks again

Mine was a quite expensive id say anywhere around £3k, did mine a few years back youll need a clutch as well.

Some will say keep it till it breaks, theres also someone who coverted to an audi box as well for cheap, have a Google around youll find info. There things called blast plates also the bolt to the older gearbox casings to strengthen them but not sure these work? From memory you may have a TY752 Box with whats believed to the weakest casing.

i run an sc36 makes 380bhp, a 42 will make 420bhp a 46 460bhp. Look on scoobyclinics site i think they still use my graph for the sc36

Lag will grow with power, they are inherently laggy unfortunately, due to the length of the headers to turbo.
You can do all sorts of tricks like rotated inlet manifold rotated turbo etc etc etc to keep the lag down. I have the stock manifold and harvey up pipe.

The new rad cap will add pressure to the system as when they fail they just let all the expansion of water go into the over flow when tired

Ask away happy to help :thumb:

Loved my v1 WRX, the power delivery was amazing. Gota love that lag. One issue you may face is is an old car with alot off old rubber, adding more pressure to the engine won't help. Maybe a remap by a better mapper.

Its definitely laggy but such a thrill to drive, It will be staying with me. I will keep the rubber in mind and plan to slowly but surely bring it all up to a good standard before any more gains. From what I've heard, Duncan at Race Dynamics knows his stuff and just reading through the forums the late Jolly Green Machine seemed to be a active and trusted member, I might be making this up but would love to know what other think of these guys. I did take it to Rich at FB tuning and unfortunately he had sold his equipment for tuning the older cars now.

Okay, the gearbox cost in the bigger picture is just another cost over time that will have to be paid and when Im financially ready It will be worth it. Definitely going to look into those other options you mentioned.

Scoobyclinics is such a useful sight for me at the moment but its dangerous, the cart seems to have got full very quicky :D I did wonder if anyone had used them and if they were a good place to turn for this stuff?

Ive been looking at the Harvey up pipes, My uncle also works for a company who build custom manifolds but that is a big expenditure to get rid of something (the lag) I actually dont mind to much, it makes it a little bit more interesting with passengers :)

Yeah, I feel like the cap is a cheap and easy way to rule it out.

Appreciate your help, it really shows that this is a proper car community, people not only have a lot of knowledge but are willing to share it which is a massive help to someone like me who loves the car but has very limited knowledge.

I was going to get mine mapped by Duncan, but heard loads of bad experiences on hear. Hence my comment.

Scoobyclinic is decent to be honest. They are, overall, very consistent in their service but they know how to charge you a good sum of money each time you go! Their turbos are from blouch in the USA if you need more info. look at Roger clarke Motorsport also, and AS Performance, personally had great support from both those companies and bought parts from both recently.

So manifold wise The standard manifold is generally known as the best for spool with any typical stainless version addding to higher bhp but slower spool This changes up in the 450+ range though

Import Car Parts aee excellent as well for genuine bits and bobs, their Killer B stuff (aussie company) seems to be excellent also.

Just a shame the forums have gone so quiet these days, there are still people on here with a plethora of knowledge to hand.

Ive read multiple posts and advise from @jaygsi above, he is definitely someone worth listening to, a good few other regulars on here worth listening to also.

Hopefully they chime in with extra advise also

Ohh okay fair enough, Im gonna read up on him. He has been a big help at the moment with just advice over text so with my experience cannot fault him yet.

Used Andy Carr before he did a good job. Although communication on the day was abit rubbish.

Heard loads of good stuff about Bob Rawle, although never used him. Only one bad review on the site.

Hi, if you've only recently bought your 30 year old Scooby, then you might not be aware of a stealth-rot issue with them, that can creep up on owners. So before you spend another penny on the mechanicals, go inspect the rear wheel arches and turrets both inside and out - and I mean remove the rear wheels and shove a camera right up inside the wheel arch, as high as your hand will go, and inspect the double skinned wall to the interior
​​​​​ of the car. That's where they go, and by the time rust has penetrated thro' to the interior, it's often beyond repair.

​​​​​​

Don't forget about the Scoobyclinic pot hole saga :nono:

I'm not sure I fall into the category of worth being listed too.

But try to assist where I can. Comments appreciated though :thumb:

As far as getting rid of some lag is concerned, you could do a lot worse than contact Alyn at AS Performance, and ask about a Harvey Smith Trick Up-pipe.

Actually we are in the USA :)

well i got 1 of the 2 things i said about you guys correct :thumb:

I appreciate the recognition!