2.1 or 2.5 For Road Car?
27 April 2012, 08:33 PM
#1
2.1 or 2.5 For Road Car?
Ok so im struggling to make my mind up. Running a 2005 sti with the following mods.. ej257 bottom end, md321t, 650cc injectors, hyperflow front mount and standard avcs heads. I've also got a 2.0ltr cdb sitting in the garage. Now which would make the best road car? do i stick with the 2.5 and have it properly built, or do i build up the cdb? All views and reasoning would be appreciated
27 April 2012, 09:05 PM
#2
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2.5 makes a real nice road car with loads of torque, i have a proper built 2.5 here with 4800 miles on it forsale as im goin more race car build pm if interested its in the forsale section
27 April 2012, 09:06 PM
#3
For me, it would be, and is, the 2.5.
Mine is forged and runs around 400/400 although I've never bothered having it on a rolling road.
The torque is what sells it, it will pull from 2000rpm in any gear, and can be driven round town etc in a slightly higher gear than a 2 litre, and less need for gear changes, easier all round.
Mine uses a small amount of oil and is losing some from the rear of the o/s cam cover too. That's to be repaired when I can do it.
But a 2.5 DOES need a 6-speed box as it will strip 4th out of a 5-speed due to the extra torque.
Mine is forged and runs around 400/400 although I've never bothered having it on a rolling road.
The torque is what sells it, it will pull from 2000rpm in any gear, and can be driven round town etc in a slightly higher gear than a 2 litre, and less need for gear changes, easier all round.
Mine uses a small amount of oil and is losing some from the rear of the o/s cam cover too. That's to be repaired when I can do it.
But a 2.5 DOES need a 6-speed box as it will strip 4th out of a 5-speed due to the extra torque.
27 April 2012, 09:20 PM
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driven a 2.0 a 2.33 and 2.5 with avcs
2.5 spools really soon and runs out of puff pretty soon, felt like it wasnt breathing too well at top rpms and felt like it was running out of power close to the redline, the midrange was phenomenal though, i was running greddy 518z turbo, never felt quick tbh, didnt have the turbo kick, felt like a n/a motor, since most of the power was in the midrange i was never compelled to rev it to its 6.5 redline, shifted at 6k and that was that.
I've driven a bi-turbo 2.0 legacy and single turbo single scroll 2.0 classic imprezas, both stock and both felt quicker than a 2.5 due to the turbo lag, when the turbo kicked in, it really kicked in and it pulled and pulled up to its 7k redline effortlessly, was always a joy to rev it! The lightweight and short-geared type-ra that i had was a particular hoot, i have terrified a number of mates in it and it was running stock 280bhp.
I then upgraded to a 2.33 with headwork and big turbo and that i feel that it is the pinnacle of subaru ownership. Spool is acceptable, with big 30/40 turbo it never felt too laggy for street use as it would gain 0.5 bar by 3.5k and have 1 bar by 4k and keep its power up to 8k rpm, when it gains full boost at 4.2k it'll spin its wheels in first 2 gears easily and it'll even drive well enough off boost! It will quite happily cruise in sixth gear at 2k rpm without losing momentum even on big inclines.
There's also a case for reliability. a 2.0 cdb is bullet proof up to 500 bhp maybe even more. a 2.5 is prone to overheating and cracking its cylinder walls, it is also known to burn more oil, but i guess that will depend on what tolerances you build it to.
If you are not sleeving the 2.5 it will never handle the same amount of power as your 2.1 cdb but it will have more midrange momentum and have better throttle response, which is better suited for everyday driving.
2.5 spools really soon and runs out of puff pretty soon, felt like it wasnt breathing too well at top rpms and felt like it was running out of power close to the redline, the midrange was phenomenal though, i was running greddy 518z turbo, never felt quick tbh, didnt have the turbo kick, felt like a n/a motor, since most of the power was in the midrange i was never compelled to rev it to its 6.5 redline, shifted at 6k and that was that.
I've driven a bi-turbo 2.0 legacy and single turbo single scroll 2.0 classic imprezas, both stock and both felt quicker than a 2.5 due to the turbo lag, when the turbo kicked in, it really kicked in and it pulled and pulled up to its 7k redline effortlessly, was always a joy to rev it! The lightweight and short-geared type-ra that i had was a particular hoot, i have terrified a number of mates in it and it was running stock 280bhp.
I then upgraded to a 2.33 with headwork and big turbo and that i feel that it is the pinnacle of subaru ownership. Spool is acceptable, with big 30/40 turbo it never felt too laggy for street use as it would gain 0.5 bar by 3.5k and have 1 bar by 4k and keep its power up to 8k rpm, when it gains full boost at 4.2k it'll spin its wheels in first 2 gears easily and it'll even drive well enough off boost! It will quite happily cruise in sixth gear at 2k rpm without losing momentum even on big inclines.
There's also a case for reliability. a 2.0 cdb is bullet proof up to 500 bhp maybe even more. a 2.5 is prone to overheating and cracking its cylinder walls, it is also known to burn more oil, but i guess that will depend on what tolerances you build it to.
If you are not sleeving the 2.5 it will never handle the same amount of power as your 2.1 cdb but it will have more midrange momentum and have better throttle response, which is better suited for everyday driving.
27 April 2012, 10:17 PM
#7
Depends on what you want, really.
I've not driven the 2.5 myself, but I have a 370hp 2.0 car in the garage and a 2.1 350hp wagon on the drive. The 2.0 is a track car, and the 2.1 is a road car at present.
The 2.1 has a smaller turbo on it (sc36), and it's got real good low down response, which is nice for pootling about in. It will happily drive at under 2000 revs.
The 2.0 has a td05-20g in it, with a lightened flywheel etc etc, and it obviously drives like a bag of poo at under 2500 revs.
For a track/fun car, out of my two set-ups, I'd definitely go with the 2.0 every time. Due to the turbo lag, with the associated turbo kick etc, it feels *so* much faster (It probably isn't in reality). The 2.1 feels like it runs out of puff towards the top end, which personally I find a bit "boring".
I know it's not the choices you listed in the first post, but if it was my car I'd go for the 2.1 with CDB and slap a reasonably big turbo on it (e.g. the 321T), rather than a 2.5 with the same turbo as that may feel a bit boring, maybe.
Everybody is different, though.. Some people love the low down torque, but I just find I miss the top end. Linear = boring
I've not driven the 2.5 myself, but I have a 370hp 2.0 car in the garage and a 2.1 350hp wagon on the drive. The 2.0 is a track car, and the 2.1 is a road car at present.
The 2.1 has a smaller turbo on it (sc36), and it's got real good low down response, which is nice for pootling about in. It will happily drive at under 2000 revs.
The 2.0 has a td05-20g in it, with a lightened flywheel etc etc, and it obviously drives like a bag of poo at under 2500 revs.
For a track/fun car, out of my two set-ups, I'd definitely go with the 2.0 every time. Due to the turbo lag, with the associated turbo kick etc, it feels *so* much faster (It probably isn't in reality). The 2.1 feels like it runs out of puff towards the top end, which personally I find a bit "boring".
I know it's not the choices you listed in the first post, but if it was my car I'd go for the 2.1 with CDB and slap a reasonably big turbo on it (e.g. the 321T), rather than a 2.5 with the same turbo as that may feel a bit boring, maybe.
Everybody is different, though.. Some people love the low down torque, but I just find I miss the top end. Linear = boring
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27 April 2012, 11:10 PM
#10
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i am with alcazar, 2.5 all the way running one my self in my classic with a td05-20g pulls like a train in any gear loads of torque my mapper says its one of the better combo's for a road car easy 400 of each never dyno'd but not to bothered its quick enough,
i do prefer this over my last car which was an classic sti ra with a built 2.1 with twin scroll feel the set up i have now is better a lot more torque,
i do prefer this over my last car which was an classic sti ra with a built 2.1 with twin scroll feel the set up i have now is better a lot more torque,
27 April 2012, 11:19 PM
#12
i am with alcazar, 2.5 all the way running one my self in my classic with a td05-20g pulls like a train in any gear loads of torque my mapper says its one of the better combo's for a road car easy 400 of each never dyno'd but not to bothered its quick enough,
i do prefer this over my last car which was an classic sti ra with a built 2.1 with twin scroll feel the set up i have now is better a lot more torque,
i do prefer this over my last car which was an classic sti ra with a built 2.1 with twin scroll feel the set up i have now is better a lot more torque,
28 April 2012, 12:57 AM
#13
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A proper forged 2.5 is a great car for the road. Yes, they don't rev to 8000rpm, but that's not what you want from a road car; you want something torquey that spools quickly and hits hard.
28 April 2012, 07:35 AM
#16
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2.5 for a road car.
I've both a 2.0L Spec C and a 2.5 STI hatch, and yes, the 2.0L is ultimately quicker and spools well given it's a twinscroll set up, but it feels manic to drive when compared to a 2.5 (where it has a more mature feel about it), it still can't beat a 2.5 in torque deliver way way down the rev range IMO and that's what you want in a road car.
I've both a 2.0L Spec C and a 2.5 STI hatch, and yes, the 2.0L is ultimately quicker and spools well given it's a twinscroll set up, but it feels manic to drive when compared to a 2.5 (where it has a more mature feel about it), it still can't beat a 2.5 in torque deliver way way down the rev range IMO and that's what you want in a road car.
28 April 2012, 07:52 AM
#17
As said above it's horses for courses, i'm not keen on the 2.5 but only because i like the kick you get from the 2.0 which just seems more urgent, with a smaller turbo like the vf34 it pulls hard all the way to the rev limit.
The 2.5 reminds me of a muscle car, and is not suited to my style of driving, i like hectic driving on twisty back roads and tracks, with hard braking and high revs to get that twitchy i'm on the edge feeling, without the speeds getting too silly, for my maximum attack mode thrills, and i obey the speed limits in populated areas, so i don't care what the car is like around town as i drive like a granny in a micra.
The 2.5 is also very expensive to do if you want to go above 450, and they get very hot very quickly.
I've not been in or driven a 2.1, so not qualified to comment, other than to say i imagine it to be an almost best of both worlds, with more low down grunt than the 2.0 but higher revs than the 2.5, it's also much cheaper to get bigger numbers, and everyone likes big numbers.
It's the route i hope to take one day, if i ever finish my house.
The 2.5 reminds me of a muscle car, and is not suited to my style of driving, i like hectic driving on twisty back roads and tracks, with hard braking and high revs to get that twitchy i'm on the edge feeling, without the speeds getting too silly, for my maximum attack mode thrills, and i obey the speed limits in populated areas, so i don't care what the car is like around town as i drive like a granny in a micra.
The 2.5 is also very expensive to do if you want to go above 450, and they get very hot very quickly.
I've not been in or driven a 2.1, so not qualified to comment, other than to say i imagine it to be an almost best of both worlds, with more low down grunt than the 2.0 but higher revs than the 2.5, it's also much cheaper to get bigger numbers, and everyone likes big numbers.
It's the route i hope to take one day, if i ever finish my house.
28 April 2012, 09:34 AM
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to the op, i suggest you drive both if you can before you decide.
I have had both, a 2.5l with a 20g which made 436/460 and a 2.1 with an s206 at 504/475
The 2.5 is a nice lazy drive and when you boot it the torque 'hit' is great but as said once it dies off if feels pretty 'meh' the Enginetuner 2.1 im running now is great, yes it takes longer to spool but the kick in the back you get is much better than the 2.5 and it just keeps going and going.
Personally i think for a fast road car a 2.1 with an sc46 would be pretty nice and bullet proof ! with a 2.5 i was always checking oil, thinking of ways to keep the temp down (they do get hot!) with the 2.1 i check the fluids once a month, they never move
I have had both, a 2.5l with a 20g which made 436/460 and a 2.1 with an s206 at 504/475
The 2.5 is a nice lazy drive and when you boot it the torque 'hit' is great but as said once it dies off if feels pretty 'meh' the Enginetuner 2.1 im running now is great, yes it takes longer to spool but the kick in the back you get is much better than the 2.5 and it just keeps going and going.
Personally i think for a fast road car a 2.1 with an sc46 would be pretty nice and bullet proof ! with a 2.5 i was always checking oil, thinking of ways to keep the temp down (they do get hot!) with the 2.1 i check the fluids once a month, they never move
28 April 2012, 10:00 AM
#19
Back to original thread - I'm a fan of lag lol. I've never understood people who aren't. I can pootle round town at low revs and drive like i'm in a normal car, then (on private roads of course) knock it down a gear and feel the shove in the back. It doesn't interest me to have a smooth delivery of power otherwise i'd buy a N/A car.
As said i'm currently building a 2.1 so one year i'll be better qualified to answer.
28 April 2012, 01:11 PM
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Thread Hijack from me lol. What spec was your 2.1?. I'm currently building a 2.1 with the aim of a moderate 400/400 and was advised to go Sc46.
Back to original thread - I'm a fan of lag lol. I've never understood people who aren't. I can pootle round town at low revs and drive like i'm in a normal car, then (on private roads of course) knock it down a gear and feel the shove in the back. It doesn't interest me to have a smooth delivery of power otherwise i'd buy a N/A car.
As said i'm currently building a 2.1 so one year i'll be better qualified to answer.
Back to original thread - I'm a fan of lag lol. I've never understood people who aren't. I can pootle round town at low revs and drive like i'm in a normal car, then (on private roads of course) knock it down a gear and feel the shove in the back. It doesn't interest me to have a smooth delivery of power otherwise i'd buy a N/A car.
As said i'm currently building a 2.1 so one year i'll be better qualified to answer.
if you want full spec PM me save clogging up this thread.
28 April 2012, 01:58 PM
#22
257 V9 crank
Wiseco Pistons
Crower Rods
V3 STI Heads
ARP Studs
ACL etc
All going into my CDB. Then as i'm fairly standard FMIC - 800cc injectors, ESL daughter-board, full 3" decat and then hopefully SC46 or TD05 20g which i understood would "just about" see me to 400/400.
Although i'll probably go lower CR, and have thought about running a really low CR for run in then possibly re-strip and change gaskets.
28 April 2012, 03:19 PM
#23
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ive had a semit built 2.5 which was running an sc46 and couldnt fault it, was fantastic, altho i was a bit scared to rev it too hard,
now got a fully built 2.1 with rotated gt35r and its exactly what i wanted
a proper kick in the back when the boost comes in, its fantatsic., yes theres a loss in low down torque, and boost is later - in 6th gear at 70mph there is lag, lol but why would anyone drive like that?but imo thats whay you have gears.
best bet, get a blast in both cars, and decide what suits you best.
now got a fully built 2.1 with rotated gt35r and its exactly what i wanted
a proper kick in the back when the boost comes in, its fantatsic., yes theres a loss in low down torque, and boost is later - in 6th gear at 70mph there is lag, lol but why would anyone drive like that?but imo thats whay you have gears.
best bet, get a blast in both cars, and decide what suits you best.
Last edited by jef; 28 April 2012 at 03:27 PM.
28 April 2012, 04:06 PM
#25
ive had a semit built 2.5 which was running an sc46 and couldnt fault it, was fantastic, altho i was a bit scared to rev it too hard,
now got a fully built 2.1 with rotated gt35r and its exactly what i wanted
a proper kick in the back when the boost comes in, its fantatsic., yes theres a loss in low down torque, and boost is later - in 6th gear at 70mph there is lag, lol but why would anyone drive like that?but imo thats whay you have gears.
best bet, get a blast in both cars, and decide what suits you best.
now got a fully built 2.1 with rotated gt35r and its exactly what i wanted
a proper kick in the back when the boost comes in, its fantatsic., yes theres a loss in low down torque, and boost is later - in 6th gear at 70mph there is lag, lol but why would anyone drive like that?but imo thats whay you have gears.
best bet, get a blast in both cars, and decide what suits you best.
28 April 2012, 04:54 PM
#26
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ive not had a chance to get in on rollers myself, only had it a few days and it had a fault that needed investigating, and rectifying, thats being done just now.
i know my i/c is holding back the cars potential abit, and ill be sorting along with trying to get underbonnet temps down a bit to try help- but thats for later after ive had a chance to really enjoy it.
but its night and day from the 2.5.
i knew the 2.5 was quick, it was a great road car and never missed a beat, and gave constant ear to ear grins,
but the 2.1 is in a different league tbh - obviously it was a lot more expensive. i had already most supprting mods on the 2.5 to swap onto the 2.1 build like brakes, suspension, 6 speed box - although its now got 1000bhp clutch in it lol. but when the power comes in it torque steers a lot and its literally like your hanging onto the streering wheel for dear life - love it!
the boost just comes in so hard in comparison to the 2.5. its not as progressive when low down, but i dint want that, i wanted to be pushed hard back in the seat when the boost came in - it does exactly that.
thats why i reckon youd need to drive both set ups to see what you like best - totally different animals
i know my i/c is holding back the cars potential abit, and ill be sorting along with trying to get underbonnet temps down a bit to try help- but thats for later after ive had a chance to really enjoy it
.but its night and day from the 2.5.
i knew the 2.5 was quick, it was a great road car and never missed a beat, and gave constant ear to ear grins,
but the 2.1 is in a different league tbh - obviously it was a lot more expensive. i had already most supprting mods on the 2.5 to swap onto the 2.1 build like brakes, suspension, 6 speed box - although its now got 1000bhp clutch in it lol. but when the power comes in it torque steers a lot and its literally like your hanging onto the streering wheel for dear life - love it!
the boost just comes in so hard in comparison to the 2.5. its not as progressive when low down, but i dint want that, i wanted to be pushed hard back in the seat when the boost came in - it does exactly that.
thats why i reckon youd need to drive both set ups to see what you like best - totally different animals
28 April 2012, 04:59 PM
#27
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ive not had a chance to get in on rollers myself, only had it a few days and it had a fault that needed investigating, and rectifying, thats being done just now.
i know my i/c is holding back the cars potential abit, and ill be sorting along with trying to get underbonnet temps down a bit to try help- but thats for later after ive had a chance to really enjoy it.
but its night and day from the 2.5.
i knew the 2.5 was quick, it was a great road car and never missed a beat, and gave constant ear to ear grins,
but the 2.1 is in a different league tbh - obviously it was a lot more expensive. i had already most supprting mods on the 2.5 to swap onto the 2.1 build like brakes, suspension, 6 speed box - although its now got 1000bhp clutch in it lol. but when the power comes in it torque steers a lot and its literally like your hanging onto the streering wheel for dear life - love it!
the boost just comes in so hard in comparison to the 2.5. its not as progressive when low down, but i dint want that, i wanted to be pushed hard back in the seat when the boost came in - it does exactly that.
thats why i reckon youd need to drive both set ups to see what you like best - totally different animals
i know my i/c is holding back the cars potential abit, and ill be sorting along with trying to get underbonnet temps down a bit to try help- but thats for later after ive had a chance to really enjoy it
.but its night and day from the 2.5.
i knew the 2.5 was quick, it was a great road car and never missed a beat, and gave constant ear to ear grins,
but the 2.1 is in a different league tbh - obviously it was a lot more expensive. i had already most supprting mods on the 2.5 to swap onto the 2.1 build like brakes, suspension, 6 speed box - although its now got 1000bhp clutch in it lol. but when the power comes in it torque steers a lot and its literally like your hanging onto the streering wheel for dear life - love it!
the boost just comes in so hard in comparison to the 2.5. its not as progressive when low down, but i dint want that, i wanted to be pushed hard back in the seat when the boost came in - it does exactly that.
thats why i reckon youd need to drive both set ups to see what you like best - totally different animals
28 April 2012, 05:29 PM
#29
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cant say anymore than , this one
and yeah kwik i do, just looking like the i/c isnt quite as capable, and could be doing with changing - its just a possibility. underbonet temps with the massive turbo, id just like to get down a bit, as its relativley, easy and not too expensive to get even a small benefit.
and yeah kwik i do, just looking like the i/c isnt quite as capable, and could be doing with changing - its just a possibility. underbonet temps with the massive turbo, id just like to get down a bit, as its relativley, easy and not too expensive to get even a small benefit.
28 April 2012, 05:35 PM
#30
and yeah kwik i do, just looking like the i/c isnt quite as capable, and could be doing with changing - its just a possibility. underbonet temps with the massive turbo, id just like to get down a bit, as its relativley, easy and not too expensive to get even a small benefit.
ET was talking the other day about experiments with temperatures. What FMIC are you running? Reverse scoop?