Forged 2.5 with std rods....want more power.......options
02 January 2018, 09:44 PM
#1
Forged 2.5 with std rods....want more power.......options
So I have a hawk sti with a forged 2.5 but it's on std rods and unsure of head studs as the previous owner wasn't ever going to go for more power, I however am starting to want more power..........alot more 
The spec is
Cdb 2.5 built by scoobyclinic 14 months ago (8k on engine)
Mahle pistons
New crank
Cosworth head gaskets
Arp rod bolts
Std rods
Heads rebuilt with upgraded valves/spings/retainers
Fmic
750cc denso injectors
Scoobyclinic Induction kit
Hybrid vf43
Decat etc
350bhp
I really feel like I need another 100bhp or so, what's the most cost effective way of going about it?
Rebuild this engine with better rods/sell this engine but that means losing the closed deck block/or push this engine over 400bhp and leave it in the hands of god?
I see so many people with 450+ 2.5's and I want to be part of that club too.
The spec is
Cdb 2.5 built by scoobyclinic 14 months ago (8k on engine)
Mahle pistons
New crank
Cosworth head gaskets
Arp rod bolts
Std rods
Heads rebuilt with upgraded valves/spings/retainers
Fmic
750cc denso injectors
Scoobyclinic Induction kit
Hybrid vf43
Decat etc
350bhp
I really feel like I need another 100bhp or so, what's the most cost effective way of going about it?
Rebuild this engine with better rods/sell this engine but that means losing the closed deck block/or push this engine over 400bhp and leave it in the hands of god?
I see so many people with 450+ 2.5's and I want to be part of that club too.
03 January 2018, 06:32 AM
#7
No mate,when I said that I was just stating that as you have the forged pistons already etc... that the rods upgrade would be what you need to upgrade next to safely get those figures that you have mentioned 450+
but you will still need all the checks done as the engine will practically be re built thats why it would of been simpler If the previous owner had just upgraded them when he had the engine open but saying that maybe he was not really looking massive amounts of power.....I was speaking to a mate of mine the other day who is running a standard Subaru sti "2006" 2.5 engine and its over 400bhp now with just the normal upgrades i.e exhaust,filter,colder spark plugs,SC42 billet turbo and a alcatek ecu,and the engine has not **** itself yet, but as they say "One mans luck is another mans misfortune"maybe he has a Wednesday car
.SJ.
but you will still need all the checks done as the engine will practically be re built thats why it would of been simpler If the previous owner had just upgraded them when he had the engine open but saying that maybe he was not really looking massive amounts of power.....I was speaking to a mate of mine the other day who is running a standard Subaru sti "2006" 2.5 engine and its over 400bhp now with just the normal upgrades i.e exhaust,filter,colder spark plugs,SC42 billet turbo and a alcatek ecu,and the engine has not **** itself yet, but as they say "One mans luck is another mans misfortune"maybe he has a Wednesday car.SJ.
Trending Topics
03 January 2018, 06:42 AM
#8
No mate,when I said that I was just stating that as you have the forged pistons already etc... that the rods upgrade would be what you need to upgrade next to safely get those figures that you have mentioned 450+but you will still need all the checks done as the engine will practically be re built thats why it would of been simpler If the previous owner had just upgraded them when he had the engine open but saying that maybe he was not really looking massive amounts of power.....I was speaking to a mate of mine the other day who is running a standard Subaru sti "2006" 2.5 engine and its over 400bhp now with just the normal upgrades i.e exhaust,filter,colder spark plugs,SC42 billet turbo and a alcatek ecu,and the engine has not **** itself yet, but as they say "One mans luck is another mans misfortune"maybe he has a Wednesday car.SJ.
but you will still need all the checks done as the engine will practically be re built thats why it would of been simpler If the previous owner had just upgraded them when he had the engine open but saying that maybe he was not really looking massive amounts of power.....I was speaking to a mate of mine the other day who is running a standard Subaru sti "2006" 2.5 engine and its over 400bhp now with just the normal upgrades i.e exhaust,filter,colder spark plugs,SC42 billet turbo and a alcatek ecu,and the engine has not **** itself yet, but as they say "One mans luck is another mans misfortune"maybe he has a Wednesday car.SJ.
03 January 2018, 08:49 AM
#10
check 'which' Mahle pistons you have also as personally i would only use the 2618 variant (good for anything you can muster) above 400..........
if you want to future proof then a "CDB insert" is again a no-brainer once above 450 IMO and you may want to consider better studs, etc.
if you want to future proof then a "CDB insert" is again a no-brainer once above 450 IMO and you may want to consider better studs, etc.
03 January 2018, 09:38 AM
#11
check 'which' Mahle pistons you have also as personally i would only use the 2618 variant (good for anything you can muster) above 400..........
if you want to future proof then a "CDB insert" is again a no-brainer once above 450 IMO and you may want to consider better studs, etc.
if you want to future proof then a "CDB insert" is again a no-brainer once above 450 IMO and you may want to consider better studs, etc.
Sell this and start again or rebuild this................
03 January 2018, 09:54 AM
#12
Scooby Regular
Join Date: Oct 2016
Location: Killin
Posts: 943
Likes: 0
Received 0 Likes
on
0 Posts
I’ve never understood why someone would have a build like this done and not opt for the uprated rods, makes no sense at all.
What you need to do is work out if it makes sense financially to ether have uprated rods fitted which you can have done and not worry about running it in or having rods fitted and a refresh which would be much more costly and you’d need to run it in.
Or buy one that’s already done and at the spec you want.
What you need to do is work out if it makes sense financially to ether have uprated rods fitted which you can have done and not worry about running it in or having rods fitted and a refresh which would be much more costly and you’d need to run it in.
Or buy one that’s already done and at the spec you want.
03 January 2018, 10:32 AM
#13
I’ve never understood why someone would have a build like this done and not opt for the uprated rods, makes no sense at all.
What you need to do is work out if it makes sense financially to ether have uprated rods fitted which you can have done and not worry about running it in or having rods fitted and a refresh which would be much more costly and you’d need to run it in.
Or buy one that’s already done and at the spec you want.
What you need to do is work out if it makes sense financially to ether have uprated rods fitted which you can have done and not worry about running it in or having rods fitted and a refresh which would be much more costly and you’d need to run it in.
Or buy one that’s already done and at the spec you want.
03 January 2018, 12:01 PM
#14
Scooby Regular
in theroy if all you wanna do is replace the rods then should only need to do a basic refresh with bearings, head gasket kit and head studs and add in the rods and maybe pistons depending on whats in it (if it was only speced for 400 before then unless clinic can tell you what went in it you'll have to presume if you want to go higher will need to replace those as well).
03 January 2018, 12:02 PM
#15
Scooby Regular
I’ve never understood why someone would have a build like this done and not opt for the uprated rods, makes no sense at all.
What you need to do is work out if it makes sense financially to ether have uprated rods fitted which you can have done and not worry about running it in or having rods fitted and a refresh which would be much more costly and you’d need to run it in.
Or buy one that’s already done and at the spec you want.
What you need to do is work out if it makes sense financially to ether have uprated rods fitted which you can have done and not worry about running it in or having rods fitted and a refresh which would be much more costly and you’d need to run it in.
Or buy one that’s already done and at the spec you want.
03 January 2018, 04:41 PM
#16
so in theory i could-
split the block and have it checked over
replace the bearings
re-use the crank that was new 8k ago
re-use pistons or replace if not up to the job
replace std rods with uprated rods
re-use heads without rebuilding them as they had a full overhaul 8k ago
new head-gaskets/timing kit and possibly 14mm head stud conversion
good news is ive just checked the paperwork from the clinic and it has been fitted with the mahle 2618 pistons
split the block and have it checked over
replace the bearings
re-use the crank that was new 8k ago
re-use pistons or replace if not up to the job
replace std rods with uprated rods
re-use heads without rebuilding them as they had a full overhaul 8k ago
new head-gaskets/timing kit and possibly 14mm head stud conversion
good news is ive just checked the paperwork from the clinic and it has been fitted with the mahle 2618 pistons
03 January 2018, 06:02 PM
#18
perhaps i take my chance and push for 400bhp and be happy with that
03 January 2018, 06:48 PM
#20
Scooby Regular
so in theory i could-
split the block and have it checked over
replace the bearings
re-use the crank that was new 8k ago
re-use pistons or replace if not up to the job
replace std rods with uprated rods
re-use heads without rebuilding them as they had a full overhaul 8k ago
new head-gaskets/timing kit and possibly 14mm head stud conversion
good news is ive just checked the paperwork from the clinic and it has been fitted with the mahle 2618 pistons
split the block and have it checked over
replace the bearings
re-use the crank that was new 8k ago
re-use pistons or replace if not up to the job
replace std rods with uprated rods
re-use heads without rebuilding them as they had a full overhaul 8k ago
new head-gaskets/timing kit and possibly 14mm head stud conversion
good news is ive just checked the paperwork from the clinic and it has been fitted with the mahle 2618 pistons
03 January 2018, 07:03 PM
#22
Scooby Regular
03 January 2018, 07:33 PM
#24
Scooby Regular
Join Date: Oct 2016
Location: Killin
Posts: 943
Likes: 0
Received 0 Likes
on
0 Posts
Still doesn’t make sense to me, if it’s being stripped down for a rebuild then it would make sense to fit the uprated rods for both peace of mind and if the desire for more power ever came.
03 January 2018, 09:41 PM
#27
Mate by the time someone has taken your engine out, stripped it, refreshed it, stuck you new rods in, put it back together, put it back in the car, stuck a new turbo on it, run it in, added any parts required for the new spec and re-mapped it, you're going to be at the thick end of £4k.... is it really worth all that for a bit more power????
My opinion is either sell it and buy something else more suited to your requirements, or just strap a bigger turbo on it and go for 420 ish... it will either go bang or it won't.
Edit to add; What do scooby clinic think it's good for as is???
My opinion is either sell it and buy something else more suited to your requirements, or just strap a bigger turbo on it and go for 420 ish... it will either go bang or it won't.
Edit to add; What do scooby clinic think it's good for as is???
Last edited by ditchmyster; 03 January 2018 at 09:43 PM.
03 January 2018, 10:34 PM
#28
Scooby Regular
iTrader: (11)
Join Date: Feb 2011
Location: Newcastle upon tyne
Posts: 2,750
Likes: 0
Received 0 Likes
on
0 Posts
Yea sounds a bit miss match that build shrek
Stock rods are pretty good as a oem item but as stated it’s heavy work & once you factor in the torque values at a higher rpm wich the 2.5 revs out very early its def worth upgrading on the build
. Personally I would replace rod & piston as a item regardless / but that’s your call .
11 mm studs are more than ample if your not chasing massive boost .. they get a good kicking don’t get me wrong but deserve more credit as a upgrade than most admit.
/ pay the extra & choose the 14 mm if your a boost addict .
... or just be happy , I’m sure it’s a capable car as is /
Stock rods are pretty good as a oem item but as stated it’s heavy work & once you factor in the torque values at a higher rpm wich the 2.5 revs out very early its def worth upgrading on the build
. Personally I would replace rod & piston as a item regardless / but that’s your call .
11 mm studs are more than ample if your not chasing massive boost .. they get a good kicking don’t get me wrong but deserve more credit as a upgrade than most admit.
/ pay the extra & choose the 14 mm if your a boost addict .
... or just be happy , I’m sure it’s a capable car as is /
04 January 2018, 09:32 AM
#29
Scooby Regular
Yea sounds a bit miss match that build shrek
Stock rods are pretty good as a oem item but as stated it’s heavy work & once you factor in the torque values at a higher rpm wich the 2.5 revs out very early its def worth upgrading on the build
. Personally I would replace rod & piston as a item regardless / but that’s your call .
11 mm studs are more than ample if your not chasing massive boost .. they get a good kicking don’t get me wrong but deserve more credit as a upgrade than most admit.
/ pay the extra & choose the 14 mm if your a boost addict .
... or just be happy , I’m sure it’s a capable car as is /
Stock rods are pretty good as a oem item but as stated it’s heavy work & once you factor in the torque values at a higher rpm wich the 2.5 revs out very early its def worth upgrading on the build
. Personally I would replace rod & piston as a item regardless / but that’s your call .
11 mm studs are more than ample if your not chasing massive boost .. they get a good kicking don’t get me wrong but deserve more credit as a upgrade than most admit.
/ pay the extra & choose the 14 mm if your a boost addict .
... or just be happy , I’m sure it’s a capable car as is /
04 January 2018, 10:21 AM
#30
Scooby Regular
iTrader: (11)
Join Date: Feb 2011
Location: Newcastle upon tyne
Posts: 2,750
Likes: 0
Received 0 Likes
on
0 Posts
I only stated Tidgy because given the 2618 is a better application piston for turbo engines due to its expansion properties it also has a shorter life cycle .
Given it’s not my engine & I don’t have the components in front of me , sure they prob fine .???
Given it’s not my engine & I don’t have the components in front of me , sure they prob fine .???
