Caterham with Duratec I4 25?

[cain-it]

I know Caterham are factory fitting I4 1.8 / 2.0 / 2.3 ... but in the bespoke build / aftermarket side, are Caterham owners using the newer I4 25 ?

If so you you link me to some build sites?

Thanks

[DCL]

I'm interested in this too. From the limited information I've got so far, it looks like it may be physically bigger in places, but it would be interesting to know what common parts, if any, it shares with the 2.0L and 2.3L.

[BBL-Sean]

On the CSR owner discussion forum, Hanns Per (goes by "Kober") put one in his CSR, and posted a thread on it there. He is located in Austria, I believe.

Edited by BBL-Sean on Monday 14th December 23:56

[cain-it]

Ok thanks Sean... from another Sean :-)

I've been talking to Raceline about the 2.5 & they're getting VERY impressive figures out of it with the typical tuning methods that used to be done to the Duratec 2.0 R500... torque + light car = :-) :-) :-) !!!. Without the cost / complexity / heat soak issues of going forced induction...

I'll have a look at the CSR forum

[DCL]

Thanks for the heads up on that thread.

I couldn't get the images to work, but clearly the head is the same. From what I could make out, the RMP limit was 6000 RPM which is a big change in character from even the standard 2L engine. The spec of head was high (higer than the R500) and but the choice of cams, UL15 & UL40, was a little strange - quite a hot exhaust, but mild inlet. Perhaps that's due to the choice of 4:2:1 exhaust (which is probably Ultimate's spec) and the long stroke.

At a guess the rest of the engine is standard - probably due to the limited availability of upgraded parts. But it looks like there's plenty to explore and it'll probably only be a matter of time before that changes.

IMHO 4 cylinder engines over 2L are vibration prone, but for road touring (at low RPM) that's maybe less of an issue than it would be on track. More CC is always a good route to take for more torque, if not always for ultimate BHP.

[Dr Slotter]

IIRC the 2.5 is the same bore as the 2.0/2.3 but a longer stroke (obviously). It was originally designed for the US market as a lower revving product for things like the Ford/Mazda small SUVs. It's also the base engine design for the mid-size hybrid (so Atkinson cycle).

[DCL]

Dr Slotter said:

IIRC the 2.5 is the same bore as the 2.0/2.3 but a longer stroke (obviously). It was originally designed for the US market as a lower revving product for things like the Ford/Mazda small SUVs. It's also the base engine design for the mid-size hybrid (so Atkinson cycle).

If the thread is to be believed, it is 89 bore x 100 stroke (and it does calculates out correctly), it is bigger on both compared to 87.5 x 94 of the 2.3L. I suspect that extra bore and stroke reflects the limits of what the block can support.

[cain-it]

I can confirm that the 2.5 head has bigger ports than the 2.0/2.3.
Thats why the intake / exhaust manifolds from the smaller engine won't fit.
This is one of my decision points now... to buy X uprated hardware for the 2.0 means it won't be compatible with the 2.5

[DCL]

For those interested, I've done a little inquiring and the 2.5 is the same as the 2.3L in height, 14mm taller than 2L. Although the head port sizes are bigger, it is interchangeable with the 2/2.3L head. The 2.5L head ports can be sleeved and modified to re-size it back to 2L size to fit available ITB. The crank has a balance shaft that needs removed and has a maximum RPM somewhere around 7500 RPM. The bigger bore means a bigger valves can be used.
As I thought, may parts are under development and should become commercially available at some stage. A steel crank, custom pistons, and rods being made and tested. It appears that they are making 300BHP comfortably and that will no doubt push up over time.

[cain-it]

DCL, from my chats with Raceline, the uprated parts required to tune the 2.5 have already been developed & are commercially available.
Not just from Raceline... all the usual Duratec tuners too : ITBs / manifolds / rods / pistons etc..

With the bigger ports in the head, not sure sleeving is the best idea, wont it restrict flow? To get 300 bhp even the bigger 2.5 head needs porting & bigger values.

[DCL]

cain-it said:

With the bigger ports in the head, not sure sleeving is the best idea, wont it restrict flow? To get 300 bhp even the bigger 2.5 head needs porting & bigger values.

Ford clearly felt the need to make the ports bigger on the 2.5L but, as the 2L port size can happily make over 300BHP, the reason may not be quite as simple as it appears. It's likely that the peak power was developed at low RPM where pulse tuning does not really play any part, and so the bigger the ports , the better.

When you go to higher states of tune, you want the pulse tuning to start to pushing more gas in (basically a volumetric efficiency of greater than one). But, achieving that state of tune with a large port may prove harder than a smaller one as gas velocities are lower and pulses weaker.

That not saying the bigger ports are a bad thing, just that you need to match them to the tune of the engine.

It's also worth saying the Duratec CNC heads don't really remove much material from the ports - they are more about tidying up the shape, finish, detail around the valves, bigger valves, and bigger valve seats if you go for the ultimate phase 3 job.

Edit to add a 'before and after' CNC work images:

Edited by DCL on Friday 18th December 10:35

[DCL]

Sorry if I'm coming over as a bit obsessed with this, but I've done a photo comparison between the two heads. The inlet uses some of the injector space to make it a little taller (as you would to try to do to make the path straighter). But the exhaust seems very similar to the standard 2/2.3L. The photo inserts show a CNC 2L head which has the exhaust opened up a little and is clearly bigger than the standard 2.5L. If your swapping a 2.3 for a 2.5 I suspect the sleeved 2.5 head option will make sense, but if you starting from scratch (and can get a ITB or manifold to size) then there's little point. Performance wise, I doubt there's a significant difference.

[cain-it]

All good info... thanks

[repsna]

hello, just popped into this thread, I am the one with the 2.5L engine in Austria.
I have the engine now for 2 seasons and so far I did 45.000km. am very happy with it.
In Spring I got new dampers from Simon Meteor which encourage to drive faster in turns with the effect that this torquey engine eats up my rear tires, only 5000 miles maximum.
The engine delivered instant high torque already at low RPM.
The engine was done with Simon Ultimate performance. When we where looking for TBs we found that all existing TBs in Diameter where smaller than the intake of the head. So we used a 2.0 Ultimate stage 3 ported head. Main reason was we do not go beyond max. 6500 RPM. Cams and pistons where specified from Simon.
So we used SBD TB's and exhaust with distinct long 2 section.
Any info you want I am more than happy to provide
Best Regards Hanns Per

[DCL]

Thanks for posting that I've been talking to Simon this week about my next project engine, and your thread got me asking about the 2.5L. I think there's been some progress since yours was built, with some race cars pushing things a little further. As I mentioned, there's some talk of a new, lighter, crank that may push RPM limits up.

Edited by DCL on Wednesday 23 December 00:13

[cain-it]

2.0 head with 2.5 short engine, hey? Very interesting... thanks for posting.

For sure over the past 2 years, you can get all the uprated equipment for the 2.5 & retain the 2.5 head with larger ports.

To get the rod ratio improved, I heard about 2.5 block with 2.3 crank & rods, giving approx 2.4

[k20erham]

Hi that's exactly what we Honda boys have to do without going to the Darton sleeving, the K20 Honda head is too big on the ex ports and one of the reasons the torque figures suffer,
2.4 bottom end with a K20 head, but alas it's 19mm taller and a no go in a 7, that's why I've gone FI.Plus I want something that will still rev to 9k and the longer stroke does not like it

[MikeE]

cain-it said:

2.0 head with 2.5 short engine, hey? Very interesting... thanks for posting.

For sure over the past 2 years, you can get all the uprated equipment for the 2.5 & retain the 2.5 head with larger ports.

To get the rod ratio improved, I heard about 2.5 block with 2.3 crank & rods, giving approx 2.4

Hasn't all this been done before by Ammo @ RaceCo - he built 2.3l, 2.4l and 2.5l and ran them all in DannyLTs R500 then built a 330bhp short stroke 2.2l from the 2.4l block and a 2L crank which he concluded was the optimum Duratec for a Caterham....this was around 2009 I think. Not sure what's happened to Ammo and RaceCo?

[DCL]

Yes, all these configurations have been tried before and the short stroke 2.2L, as I understand it, was very successful. But, for whatever reason, you don't see that specification (or a least hear about them) that much. Ammo wound up his engine business and moved on to other things.

But what is new, is the ready supply of new 2.5L crate engines. I can't recall them being available so cheaply before.

[tight fart]

Ammo is currently back packing around the States with his camera, search on Facebook and you'll find him and his pics.