Duratec 2.5 question

[waltermitty]

O.K. building Birkin with Duratec 2.5 power. There is a treaded plug in the side of the block, right side near rear. I think you can use a block heater in the hole. What size is it? I need to use it for the coolant temp sensor probably with a 1/8 npt or 3/8 npt single wire sensor for the coolant temperature gage.

[wemtd]

Pm me your e-mail I have some manuals for the engine

Right/left?? Intake or exhaust? Holes for the egr are at the back, intake side

 

P.

[waltermitty]

Got the EGR blocked off with plate from Massive. Threaded plug is on exhaust/passenger side. PM sent.

[papak]

It's ¾"-18. You can get an adapter from Earls or Summit that allows you to use a ¼ NPT sender. In my case, I use this for the coolant temp sender for the electric coolant pump controller.

[waltermitty]

Thanks!

[peterk]

waltermitty

what if any mods are you doing to the internals of the engine?

If you upgrade the crankshaft and the rods + pistons you could do huge HP and torque.

 

Seeing as the engine has more torque than your normal 2.0 engines, are you going to use a higher ratio differential . I know the caterhams with 2.3L engine used those higher diff ratios(lower number).. some even suggest 3.14. That would allow you to rev the engine higher at lower rpm.

have you made any decision on that?

 

Anyone driven a 2.5 duratec AND a 2.0 Duratec... ..... what differences does one feel at the wheel?

regards

Peter

Edited June 15, 2017 by peterk

[Nick OTeen]

I know the caterhams with 2.3L engine used those higher diff ratios(lower number).. some even suggest 3.14. That would allow you to rev the engine higher at lower rpm.

If you are revving the engine higher, how can you simultaneously be at a lower rpm?

[Kitcat]

Gotta be "go faster at lower rpm's"? Or, get more top speed out of each gear?

[Tbox56]

I have driven both, my demo with a 2.0 all stock bottom end with Crower stage 2 .389/.373 lift cams, Jenvey throttle bodies. The 2.5 is a recently completed customer's car with 11.5:1 pistons forged rods 4.10 lift cams and AT Power throttle bodies. Dyno results, converted to sea level from 6500', (where we are located) 260 hp on 91 octane pump gas. At 6500' the 2.0 pulls strong to the rev limit of 7000 and most of the time you can go to full throttle at will without undue tire spin. With the 2.5 it pulls very strong to 7000 and seems to rev as quickly as the 2.0. You must "apply throttle" to avoid undue tire spin. Driving the 2.0 a couple of weeks ago in Austin at COTA the 2.0 felt like the 2.5 at 6500'. I have not driven the 2.5 at lower elevation but I can safely say it will be a rocket with huge amounts of torque and seemingly not revving slower that the shorter stroke 2.0. Both cars are XS (wide body) Birkins with the same tires and gearing.

Tom

Birkin Direct-USA

[peterk]

yes, i should have chosen my words better.

It should read "rev the engine higher at a lower speed"

 

If the car is a road car, speed limits where i am at 110kph would get you to 3rd gear, but a little more refinement with the differential would allow you to hit 4th gear at 110kmph.

I guess it depends on whether you count the "music of the engine gear changes" a part of the fun of having a birkin 7.

Some people install 2.0 duratecs as they say it allows them to rev higher , which is more fun.

But colin chapmans philosophy in designing the car never really mentioned that the engine should "rev" easy, so its not part of a lotus 7 design feature.

Here in AUstralia, everyone uses the 2.0 duratec, seldom the 2.3. which are being phased out, and no one i know of has a 2.5........ yet

[peterk]

Tom

Which car do you prefer, the 2.0 or 2.5 birkin for the road given your experience in them.? I understand the 2 engines are basically the same weight, so it woint effect performance (power/weight ratio), the 2.5 a tad higher in height.

Seems the 2.0 is a much cheaper option money wise, just change the cams. People often say its best to upgrade the internals on the 2.5 as its a stroker version of the 2.0 .\

regards

Peter

[Tbox56]

They have different personalities, the 2.0 needs to be run harder but doesn't complain, I run it to 7000 all the time. The 2.0 with just adding the Crower cams is a very reasonable cost the only other things you need to do are change to a Receline wet sump, add throttle bodies and sort out how you want to handle the water pump and alternator belt routing.

The 2.5 requires less effort, as far as how hard you need to push the engine, to do what you can do with the 2.0. The 2.5 requires more modification than the 2.0, remove the balance shaft (19 lbs, much is rotating mass), change to the Raceline wet sump, change to a low profile cam cover, AT Power throttle bodies (only company I have found with the shorter direct to head throttle bodies for the 2.5 that will fit under the bonnet, very nice but more expensive than Jenvey) and then sort your belt routing.

A note on the low profile cam cover, our cam cover was made for the 2.0 and 2.3, which don't have variable cam timing, the 2.5 has variable intake cam timing which is part of the front camshaft bearing cap, it is one piece that bridges both the intake and exhaust cams. To use the cam cover (needed for bonnet clearance) there is extra machining needed to the head to make everything fit. This is another additional cost on the 2.5.

I might have driven the 2.5 50 miles, I have many thousands of miles in a 2.0 and like them both for different reasons. If you like momentum driving over brute force the 2.0 is for you and it makes plenty of power for a 1285 lb car.

 

Tom

[peterk]

Tom

yes i see your point, the 2.0 is much easier to go with in time and money. I do like the idea of buying a new engine and just doing the cam work upgrades, will just take a day. Surprisingly the 2.0 and 2.5 cost the same new from the factory.

 

In regards to your own 2.0 car, what HP and torque increase do you get with the crower camshafts jenvey ITB.? I havnt seen any figures stated anywhere.

 

For the OP, I understand the same camshafts can also be used on the 2.5. More power to you on your build, i have built complete engines and know how it is when you get into it all.

Peter

[waltermitty]

The 2.5 is rated 170 hp in the '12 Ford Focus. With the ATPower throttle bodies designed for the 2.5, Crower street cams, and the Birkin 4 into 1 headers I can't see how it will make less tha 200 hp. I will be running the Subaru 3.70 rear which gives about 140 mph at redline in 5th with the T9 transmission. Not real sure how launch will feel with T9 with just tall 1st. 2nd. The biggest pain with the 2.5 has been pulling head to get it modified for low profile cam cover.