so ive been speaking with mark at thwaites and ive decided to dabble in a little more power for my hawk sti as im bored of the current set up. at the moment my car is running 354bhp + 400ftlbs on the below spec

closed deck 2.5
standard rods with arp rod bolts
mahle 2618 pistons
nitrided crankshaft
acl bearings throughout
heads rebuilt with upgraded springs and retainers
cosworth head gaskets

the engine was built late 2016 by scoobyclinic and has covered around 15k so far,uses no oil/water.

the rest of the car is ready to handle more power

japspeed fmic
rcm induction kit
3" decat exhaust (afterburner vortex) + rcm wrapped headers will be going on with a trick up-pipe from as performance
new walbro pump
750cc denso injectors
ap racing clutch

im really tempted by the sc42+ turbo in the for sale section but is that a 450bhp rated turbo? if so would it be too much for my car as it has standard rods?

would i be better off with a 400bhp rated turbo maybe the mdx555 - 400bhp unit?

i also mentioned meth and mark mentioned octane booster which ive never really considered or know little about it. he says he has pushed std rods to 450ftlbs before but i would probably feel better keeping them around the 420ftlbs mark.

cheers

 

i wouldnt wanna go more than 400 at most on the stock rods. might be better time for a refresh and do the rods

 

just dont wanna be spending that sort of cash in the current climate mate, i was planning on a new car but current happenings have thwarted that now.

 

Because a turbo can produce X amount of BHP power does not mean that it has to be mapped as such, the SC42 would be a really nice upgrade on your engine....just get it mapped sensibly and your good to go, plus you would be future proofing as you would be able to increase the power when it suits you with the same turbo,if you have got the money Shrek"Go for it".SJ.

 

mark did say he can map it and cap the torque level, my concern is that i wouldnt feel a difference as mine is already 400ftlbs - would i notice another 20/30 ftlbs and 60/70 bhp?

hearing alot of different opinions on what the std rods can take isnt helping matters

 

I do agree with you also Tidgy.SJ.

 

Shrek what turbo are you running at present?.SJ.

 

hybrid vf43 mate, from the paperwork i have it has a billet wheel and i think either a different exhaust housing or something like that

 

Lol who rebuilds a poo.5 with standard rods
seems a half ar5ed thing to do

 

In my opinion you would notice the difference the spool up and midrange would definitely be improved plus the turbo would be working much less for the same power.SJ.

 

thanks buddy, its mid-range i feel that needs improving. whats your thoughts on octane boosters?

 

becuase not everyone is loaded or wants mega power, the owner at the time didnt wanna go more than the stock turbo so about 330 so was an unnecessary cost.

 

correct buddy, the bill was £7.5k from the clinic and he just couldnt stretch to have the rods done. its a shame but it is what it is, i bought the car on mileage/condition and told myself that 350bhp would be enough..................oh how i was wrong lol

 

I run Nitrous Formula octane booster and have been for years now especially after my rebuild,its not methanol but it does add protection to the engine by keeping the octane level as it should be for performance vehicles, put it this way mate when I don't add it I notice a small drop off in performance.SJ.

 

would i have to have different maps for it or can i just bung some in whenever i feel like it?

thanks

 

No mate just chuck it right in,i usually do it when I am giving the car a good drink,most of the time my fuel tank would be around 3 quarters empty I just add the NF octane booster in and then top up with Shell Optimax/V power.SJ.

 

What was the deciding factor for going with rcm headers over porting the standard ones?

 

ok mate thanks for the info, thats probably what i would do as i fill up every 4/5 weeks.

 

ive used them before and got good results from them

 

cool. I’ve got a sc42 on my 2.5 I think it’s a great turbo, you wouldn’t be disappointed even if you Cappet it? I jump nearly 60hp over the vf43 notice a huge difference not just performance wise but a much nicer drive.

 

Please don't take this as a negative comment but, personally, I wouldn't bother. You're already at 400ftlbs and the rods you have are just about at their limit there. You're planning to shell out at minimum £1500 by the time its mapped and for what? Power/torque in a different position in the rev range and possibly more lag.

I actually cant believe the engine had the valve springs and retainers done before doing the rods. The heads aren't needed to be fettled below 500hp..

 

whats the spec of your engine?

 

I’ve got forged internal
Id 1050x injections
fmic
perrin filter
3” exhaust with decat
ported oem headers with trick up pipe
sc42

made 433hp 440ft

 

you got a graph to show?

 

 

That's awesome spool mate.
think I need to do it

 

It is a great drive.

 

Tech hasn’t changed since the last couple of times you posted this fella.

I’d use the smallest turbo you can for your goals and enjoy a driveble car. I run the SC360 billet turbo and it made 377 at 1.3bar on last dyno and I was told With a map tweak it will do 400 no problem. I’ve added to the spec a bit and I’m confident it’ll do the numbers without breaking a sweat.

I wouldn’t rush out to do the rods for your goals, but if they were to fail running 400+ you can’t be too surprised.

 

Ok
My point was the engine has been built to fit a budget.
all you are now doing is pushing it to the limit of its weakest component I.e. the rods.

If you want more power the answer is to correct the weakest link now and fit forged rods.

I realise this is costly but not as expensive as when it either bends or exits the block altogether.

 

yeah you are right buddy, its around £3000 to remove and rebuild with manley tuff stuff rods providing my pistons/crank/block are ok,no reason they shouldnt be as it has 0 issues now so it should be a case of.....

new bearings throughout
new rods/bolts
upgrade to 14mm head-studs (currently arp 11mm)
re-seat the valves/inspect the heads
re-ring the pistons and hone the block
re-face heads/block and re-build using new cosworth head-gaskets
new timing kit which needs doing this year anyway regardless of which path i choose
inspect and replace if needed the oil pump
full block gasket kit
possible upgrade to an after-market pick-up pipe and baffled sump