R1 engine with 3.14 diff?
Discussion
Hi all,
Has anyone ever fitted a 3.14 diff along with a r1 engine in one of their kits?
We have a 3.38 fitted at the moment but cant help wondering what the effects of fitting a 3.14 would be.
We have a nurburgring trip lined up so the higher top speed would come in useful.
We have had the car rolling roaded and set up- it gave 130bhp at the wheels @11000rpm. The car would seem to max out at 120mph (gps) if I was to ever test the top speed.
(5PW 2003 R1 engine in a MNR in our case)
Has anyone ever fitted a 3.14 diff along with a r1 engine in one of their kits?
We have a 3.38 fitted at the moment but cant help wondering what the effects of fitting a 3.14 would be.
We have a nurburgring trip lined up so the higher top speed would come in useful.
We have had the car rolling roaded and set up- it gave 130bhp at the wheels @11000rpm. The car would seem to max out at 120mph (gps) if I was to ever test the top speed.
(5PW 2003 R1 engine in a MNR in our case)
I think i have the same engine and diff ratio as you, but I run 185/60/14 tyres and mine pulls over 130mph GPS ( I had it 128 GPS last weekend at Bruntingthorpe but it was running a bit sick due to no alternator output and would not hit the limiter in 6th) There is one Fury which runs the 3.1 diff but his R1 is 2005 I believe and he has a 1st gear of over 70mph, which is a tad too tall I think. Mine is 56 in first, 76 in second. It is all a bit of a compromise, I would personaly run taller rear tyres and then have the option of quick acceleration flor sprints ect. on 13" tyres if need be. I do not think you can easily get 140+mph from an R1 but you can make it a bit sluggish in 1st with too tall ratio. 130mph is quick enough for most UK circuits, with a few exceptions. I am hopefully doing the ring 21st Septermber in mine so I will find out how suitable it is then.
Furyblade_Lee said:
...mine pulls over 130mph GPS ( I had it 128 GPS last weekend at Bruntingthorpe but it was running a bit sick due to no alternator output and would not hit the limiter in 6th)
At risk of stating the obvious, that's with a Fury, though, which has significantly better aerodynamics than an MNR or similar 'open-wheeled' Seven-type cars. From my experience of the power needed to drive the barn-door of a Seven through an aerodynamic brick wall, I'd be pretty surprised if you could pull more than a genuine 125mph on that output. Very rough calculations suggest that if you're running out of revs at 120mph at the moment, then changing to a 3.14 diff (which would giveabout 8% taller gearing) would be giving you a theoretical peak speed of 130mph, so the chances are you might find that the car wouldn't quite pull to peak-power revs in top gear.
It's unlikely to force you so far off your power peak that it couldn't pull more than the 120mph it can manage at the moment, though, so I guess it's a case of balancing the slightly more relaxed cruising revs and maybe another 5mph on your top speed against the downside excessively tall first gear that Lee pointed out?
I have an R1 powered MK Indy (with 3.62 diff) and at the track day I did, which had a mile long straight (runway)it managed about 121 mph flat out. My speedo was reading about 1% under as I had checked it with a GPS about a week earlier. The Caterham R500 passed me quite easily!!!
Lee
Lee
Edited by leemarkadams on Thursday 13th August 20:06
Teabagger - leave the diff for your trip and we'll talk out there.
My Megabusa came with a 3.38, our first trackday was Brands Hatch and we topped it out at 120/122mph, whatever it gives. With this in mind we thought we would hit much higher speed at most other tracks as the Brands straight isn't too long...especially as we knew it was going to the Ring. We changed the diff to a 3.07 which would give 133, or 140 if we raised the 6th gear rev-limit. So far we have hit no more than 120 or so at any other UK track...Anglesey was about 115, Cadwell was 120 in 2 places on the lap, Oulton was 115 or so and even Snetterton was just over 120 as we had wind against all day (but our exhaust is losing us power) The cars just seem to get to 110 very fast and then creep up very slowly. My brother is certain it is slower in a straight line due to the longer ratio's but i'm not sure.
Anyway, leave the ratio for now (its probably too late now anyway) and we'll compare notes at the Ring. If we don't hit comfortably more than 120...into the 130's we will change the diff back. We should do though as there are downhill straights...i.e. foxhole and the run upto SX.
We'll see. Hope this helps mate.
My Megabusa came with a 3.38, our first trackday was Brands Hatch and we topped it out at 120/122mph, whatever it gives. With this in mind we thought we would hit much higher speed at most other tracks as the Brands straight isn't too long...especially as we knew it was going to the Ring. We changed the diff to a 3.07 which would give 133, or 140 if we raised the 6th gear rev-limit. So far we have hit no more than 120 or so at any other UK track...Anglesey was about 115, Cadwell was 120 in 2 places on the lap, Oulton was 115 or so and even Snetterton was just over 120 as we had wind against all day (but our exhaust is losing us power) The cars just seem to get to 110 very fast and then creep up very slowly. My brother is certain it is slower in a straight line due to the longer ratio's but i'm not sure.
Anyway, leave the ratio for now (its probably too late now anyway) and we'll compare notes at the Ring. If we don't hit comfortably more than 120...into the 130's we will change the diff back. We should do though as there are downhill straights...i.e. foxhole and the run upto SX.
We'll see. Hope this helps mate.
matt frost said:
Teabagger - leave the diff for your trip and we'll talk out there.
My Megabusa came with a 3.38, our first trackday was Brands Hatch and we topped it out at 120/122mph, whatever it gives. With this in mind we thought we would hit much higher speed at most other tracks as the Brands straight isn't too long...especially as we knew it was going to the Ring. We changed the diff to a 3.07 which would give 133, or 140 if we raised the 6th gear rev-limit. So far we have hit no more than 120 or so at any other UK track...Anglesey was about 115, Cadwell was 120 in 2 places on the lap, Oulton was 115 or so and even Snetterton was just over 120 as we had wind against all day (but our exhaust is losing us power) The cars just seem to get to 110 very fast and then creep up very slowly. My brother is certain it is slower in a straight line due to the longer ratio's but i'm not sure.
Anyway, leave the ratio for now (its probably too late now anyway) and we'll compare notes at the Ring. If we don't hit comfortably more than 120...into the 130's we will change the diff back. We should do though as there are downhill straights...i.e. foxhole and the run upto SX.
We'll see. Hope this helps mate.
OK, It seems we need to have a transmission chat over a few pints. Its all good!My Megabusa came with a 3.38, our first trackday was Brands Hatch and we topped it out at 120/122mph, whatever it gives. With this in mind we thought we would hit much higher speed at most other tracks as the Brands straight isn't too long...especially as we knew it was going to the Ring. We changed the diff to a 3.07 which would give 133, or 140 if we raised the 6th gear rev-limit. So far we have hit no more than 120 or so at any other UK track...Anglesey was about 115, Cadwell was 120 in 2 places on the lap, Oulton was 115 or so and even Snetterton was just over 120 as we had wind against all day (but our exhaust is losing us power) The cars just seem to get to 110 very fast and then creep up very slowly. My brother is certain it is slower in a straight line due to the longer ratio's but i'm not sure.
Anyway, leave the ratio for now (its probably too late now anyway) and we'll compare notes at the Ring. If we don't hit comfortably more than 120...into the 130's we will change the diff back. We should do though as there are downhill straights...i.e. foxhole and the run upto SX.
We'll see. Hope this helps mate.
Diff Codes ( Ford Sierra Diff codes, Differential Codes, Diff Numbers, Sierra Diff )
Ford axle codes
A=3.36 B=3.77 D=3.92 F=3.842 J=4.056 K=3.31 M=3.14 N=4.29 P=3.58 J=3.62 V=3.33 Z=3.59 2=4.27 3=3.62 4=3.82 5=3.26 6=3.12 8=3.56
3,14 CW47-Pin15
3,38 CW44-Pin13
3,62 CW47-Pin13
3,92 CW51-Pin13
3,77 CW49-Pin13 6.5 inch diff
3,38 fitted to 1,6 OHC ECO 5 speed
3,38 fitted to 2,0 OHC HC
3,38 fitted to 2.3 v6 ESTATE
3,14 fitted to 1,6 OHC ECO 4 speed
3,14 fitted to 2.3 v6 SALOON
3.14 fitted to 2.3 Diesel
85GG 4006 DC --- 3.97
85GG 4006 BC --- 3.62
85GG 4006 AC --- 3.38
85GG 4006 FB --- 3.36
87BG 4006 GB --- 3.14
86GG 4006 AAA --- 3.92 LSD
V87BB 4006 BAA --- 3.62 LSD
V87BG 4006 CAA --- 3.38 LSD
85GG 4006 AAA --- 3.36 LSD
Vin plate codes for Diff ratio
Ratio Code
3.14 M
3.36 A
3.38 V
3.62 U
3.64 3
3.92 D
Ford axle codes
A=3.36 B=3.77 D=3.92 F=3.842 J=4.056 K=3.31 M=3.14 N=4.29 P=3.58 J=3.62 V=3.33 Z=3.59 2=4.27 3=3.62 4=3.82 5=3.26 6=3.12 8=3.56
3,14 CW47-Pin15
3,38 CW44-Pin13
3,62 CW47-Pin13
3,92 CW51-Pin13
3,77 CW49-Pin13 6.5 inch diff
3,38 fitted to 1,6 OHC ECO 5 speed
3,38 fitted to 2,0 OHC HC
3,38 fitted to 2.3 v6 ESTATE
3,14 fitted to 1,6 OHC ECO 4 speed
3,14 fitted to 2.3 v6 SALOON
3.14 fitted to 2.3 Diesel
85GG 4006 DC --- 3.97
85GG 4006 BC --- 3.62
85GG 4006 AC --- 3.38
85GG 4006 FB --- 3.36
87BG 4006 GB --- 3.14
86GG 4006 AAA --- 3.92 LSD
V87BB 4006 BAA --- 3.62 LSD
V87BG 4006 CAA --- 3.38 LSD
85GG 4006 AAA --- 3.36 LSD
Vin plate codes for Diff ratio
Ratio Code
3.14 M
3.36 A
3.38 V
3.62 U
3.64 3
3.92 D
Yeah that'll be fine for you then, you shouldn't hit more at any other circuit. With our diff in mind, our aim was to hit 130 at the Ring, otherwise we would change back to the 3.38. The car was doing low 130's each clear lap at Foxhole and before SX (speedo is less than 1% out) and that was with 2 people in the car the whole time, so that wasn't too bad. A 3.14 is the ideal for my car all circuits considered, but a 3.07 which is on there now still works well despite being a tad long. However once I get a decat exhaust made up for it that'll help it along massively. I drove it with one on and it was so much faster but just didn't fit properly. The Westy silencer is losing us power.
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