Duratec Build Info

[MK1_Oz]

Spent hours researching this forum for Duratec info and was hoping to find a one stop shop summary that somebody had done. Alas could not find such beast. I am considering building a Duratec to comply with the technical regulations of the events I enter. I am unsure whether to have a max capacity of 2.3L or 2.5L. It has to run on carbs. Most other things are free.

From what I have discovered the following applies (correct me where I am wrong);

• post Sept-08 heads (so called hi port) are better than earlier heads and are worth 10-15HP
• standard crank is good for 8500rpm and XX(?)HP
• 1mm oversize exhaust and intake valves make a decent difference
• standard head can achieve up to low to mid 200'sHP?
• bearings need upgrading
• cam timing chain needs upgrading to thicker chain
• sprokets need keying to the crank
• to get >low 200'sHP need to change cams
• need forged pistons and rods for any sort of decent HP reliability
• head studs a good option for higher HP
• minimal gains to be made from porting heads
• need a one piece lightened flywheel

At the end of the day these are engines like any other and the usual rules apply.

If I build a new engine I would like around 260-270HP to make it worth while assuming that is a realistic target;

1. Would I start with a 2.0L block or 2.3L block?
2. Would the additional capacity come from bore, stroke or both? (Think I read the 2.3L crank doesnt like to rev?)
3. Just how much porting is required? Are the off-the-shelf upgraded heads from the various manufacturers worth it?
4. Will carbs kill the power vs throttle bodies?
5. Any real need for a steel crank? $$$$$$$
6. I will dry sump although not sure if there are too many pros and cons of internal vs external pump?

Are there any decent Duratec build books out there?

Any info greatfully appreciated.

[Graham]

ive never built one, but ive seen a good few on the rollers,

on throttle bodies a totally std 2.0 can just scrape 200bhp, so i dont see hwy you should get there with carbs all be it big ones.
ive seen quite a few in all different capacities that all top out at about 300bhp, the only real difference seems to be the bigger the cc the less revs you need. but ive been at teh rollers and they have all been to 10K apprently the std 2.0 crank is good for it ( dunno what cranks the others had)
it seems in the real world theres not a huge gain from porting heads, ive not tested one but dave walker told me they follow 170 odd cfm (10") out the box, or about 30% than you will get from the best pinto heads. he also said a std 2.3 on fast road cams with a very slight tickle to the head has seen 230-240bhp, so add in some steel rods, high compression and rally cams you are there

[MK1_Oz]

Thanks Graham. Sounds like I can achieve my goals. I will have to start costing this beast out once I get a few more peoples' input - Dobuy you around?????

[eric]

I'm currently running a home built 2.0 Duratec with the later ported head, it has a std crank forged rods pistons Kent cams etc made 270bhp with 185 torque @ 8400rpm

If you need more go with the 2.5 block I believe sbd use a 2.3 crank (ends up making a 2.4) with there rods and pistons not cheap but will be in the region of 320bhp with 220lb of torque

[Forest_rallying]

I am hoping to build a 2.5 Duratec engine one day. I have donor engine, forged pistons and steel rods, dry sump and high port head. I shall be looking for a torquey 300bhp on throttle bodies.

Considering the Duratec has been around there's very little tuning information about, as far as I know there are no books around to give you any information.

You could try giving Paul Gardner Racing Engines a call, he's doing the 2.4 and 2.5 short engines. For head work Neil Roper is your best bet.

If Gardner tells you his engines are 300 bhp, they are. All his engines are tested on an accurate calibrated static dyno.

[MK1_Oz]

Cheers Forest.

Eric - I assume you have fairly wild cams in that engine? Did you do much/any porting work? Std or +1mm valves? Sounds promising - I would be very happy with 270HP!!

[MK1_Oz]

Cheers Forest.

Eric - I assume you have fairly wild cams in that engine? Did you do much/any porting work? Std or +1mm valves? Sounds promising - I would be very happy with 270HP!!

[Lmr025]

I've got a Sbd 2.4 engine vibrates a lot compared to 2.0 ,made 229 photos at wheels my 2.0 sbd 307hp kit made 258hp at wheels not a smooth engine thinking of going back to 2.0

[eric]

Cheers Forest.

Eric - I assume you have fairly wild cams in that engine? Did you do much/any porting work? Std or +1mm valves? Sounds promising - I would be very happy with 270HP!!

Not really I used DTEC-35 http://www.kentcams.com/product-deta...5-Competition/ with a late ported head and std valves I did make sure the inlet was port matched and a quality exhaust was used also the cam timing piston squish etc was spot on.

[eric]

The head was worked on by http://www.aldevelopments.com/ it's the 2nd one Andrew's has done and both worked well

[Gyver]

Good thread!
Im taking notes
I've got a st150 engine myself that's destined for my mk2 fast road/trackday escort...

[itsawindupuk]

Eric your engine sounds similar to mine for my MGB! Ive built a st150 engine, D-Tec35 cams, 12.5:1 compression, supertech pistons, K1 forged rods etc etc. I don't have throttle bodies yet, was going to go with the raceline direct to head 48's. What bodies did you use?

[MK1_Oz]

All great info fellas.

Sounds like i could easily clean up the heads myself and port match to get good power.

What octane fuel are you using with 12.5:1?

Are you using the std timing chain? I believe there is a slightly thicker one available?

[eric]

Eric your engine sounds similar to mine for my MGB! Ive built a st150 engine, D-Tec35 cams, 12.5:1 compression, supertech pistons, K1 forged rods etc etc. I don't have throttle bodies yet, was going to go with the raceline direct to head 48's. What bodies did you use?

I reused the std 45mm Jenveys from my st170 engine and used a Jenvey Manifold which was also matched to the inlet ports, Steve mapped the engine at Track and Road and was surprised on the power it made.

[Ianbavs]

Thinking of taking mine to track n road are they any good ? What power did it make how long did it take them to tune it cheers


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[eric]

All great info fellas.

Sounds like i could easily clean up the heads myself and port match to get good power.

What octane fuel are you using with 12.5:1?

Are you using the std timing chain? I believe there is a slightly thicker one available?

Mapped on BP 98ron, the std timing chain was reused with new guides and a modified chain tensioner

[eric]

.

[Forest_rallying]

I think we are all surprised at that power, normally that sort of spec you'd expect to see approx 250 bhp on a 2.0. Was it on a static dyno or RR?

[Ianbavs]

How long did track road take to tune it ? What did it make at the wheels there cheers


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[eric]

It was run in on the rollers overall was about 3 to 4 hours, 225bhp @ the wheels

[eric]

I think we are all surprised at that power, normally that sort of spec you'd expect to see approx 250 bhp on a 2.0. Was it on a static dyno or RR?

That what I was expecting , Steve did comment "not seen many Duratecs as good as that"

Track and Road http://www.tracknroad.com/

[itsawindupuk]

I'm surprised you got that power on 45's. I was planning on using direct to head 48's and getting 45's at a later date for my spare engine but if I could use 45's on both it'll save a lot if money as only need one set.

[eric]

I'm surprised you got that power on 45's. I was planning on using direct to head 48's and getting 45's at a later date for my spare engine but if I could use 45's on both it'll save a lot if money as only need one set.

I spent awhile on optimizing the compression, gaping the rings for my required use flowing the inlet etc and used in my opinion one of the best machine shops that can machine to a very accurate tolerances , the head and block was skimmed to the minimum to re true the surfaces also.

[MK1_Oz]

A number of the companies supplying complete Duratec engines or developed heads appear to use new heads stating that the old ones may be soft or the valve seats too worn. Are these legitimate issues given people have been using very old alloy heads from other cars for years (YB)? I realise the lash cap design means the valve height has to be within a certain range but I doubt a sub 100,000km engine would show significant wear to the seats plus if going to +1mm oversize valves this issue would be circumvented? The local wreckers sell Duratecs inc a high port head for around AUD$600 (350 of your pound thingies). It would be FAR cheaper (probably) to get the bigger valves machined then do some basic porting myself.

Nobody has commented yet on capacity changes. With the Duratec is this best achieved by starting with a 2.3L engine, using a 2.3L crank in a 2.0L block and/or increasing the bore? What is the max. bore size for a 2.0L block??

Is the 2.3L head any better than the 2.0L head for a higher HP Duratec?

[eric]

The engine I used was high mileage with a knocking bottom end which was going for scrap the head needed skimming and and valve seats recutting which is normal on any engine, just re-shim the buckets as required.

For a larger capacity use the 2.5 block and use a 2.3 crank with rods to suit (ends up making a 2.4) and stick with the later 2.0 head as with the 2.3 head the inlets are too big.

[eric]

For the 2.0 go to 88.00mm which .5 oversize from std you can go to the next size but is not recomended unless in a mid state of tune

[MK1_Oz]

The engine I used was high mileage with a knocking bottom end which was going for scrap the head needed skimming and and valve seats recutting which is normal on any engine, just re-shim the buckets as required.

For a larger capacity use the 2.5 block and use a 2.3 crank with rods to suit (ends up making a 2.4) and stick with the later 2.0 head as with the 2.3 head the inlets are too big.

Bugger.....that's now 3 engines I need to buy from the wreckers!! But I am starting to get some good info here...

I am allowed to increase capacity to 2332cc under the regulations (+17%). A 2.5L block with 2.3L crank and 2.0L head makes 2339cc which is spot on +17% (rounded down ) so all good there. Does the 2.3L crank rev as hard as the 2.0L (I have read just over 8K but also read some go +9K???) and I assume both are cast not forged? The increased stroke should result in better torque?

Does the 2.3L crank fit into the 2.0L block or are they the same block bottom end other than the stroke??

Does it matter if I start with a Ford engine or a Mazda version???

[Forest_rallying]

You are better just sticking to the 2.3 engine OZ and save your money for other modifications, no point throwing money away buying a 2.5 engine too.

You can buy a decent set of rods and pistons and then get your high port head worked on. With such a long stroke crank of the 2.3 and even longer stroke of the 2.5 I would think 8k would be the absolute max on a std crank.

As for over boring I don't think there's a lot of material in the bores to machine so they are best kept close to std. It's not like there's a big advantage to be gained anyway.

[MK1_Oz]

Well it sounds like the 2.0L can make high 200'sHP which is where I want to be so maybe I should just stay with a 2.0L that has the shorter stroke (still longer than a Pinto's) and will rev harder. I am not somebody that wants to rev an engine for the sake of it but they do sound better 8k+

Keep the info coming peoples.........this will be a great thread for others too given the relatively snall amount of Duratec info out there.........

[what?]

I notice you are in adelaide, have you spoken to roger carrol? A very knowledgeable guy.

[MK1_Oz]

Not spoken to Roger as yet but I am aware that he is a go to man on Duratecs. I am sure I can find out where he hides nearer the time. I will talk to him once I have specific questions or parts requirements.

[gazz]

hey there mk1_oz,
Rogers user name is Durescort i believe on this forum. durescort@gmail.com


this should be his email if you wanted to give him a shout, he lives down Dulwich way. he is a guru when it comes to these engines and sells some quality gear for a conversion.
i believe some Mazda duratecs came with a forged crank as standard equipment, not sure which, but if you wanted to go that route then you could get one of those. alternatively they are fairly cheap from the US to get a nice shiney new forged crank. circa $500US.

if you want the capacity and its allowed for your class then i cant see a reason to go down the 2.0l route. you might as well go straight for the 2.3. plus you cant really bore them out as was said before. thats my 2c.
either way, it does start to get expensive, as i am finding out. the 2.3 and 2.0 are basically the same engine. not sure about the 2.5...

if you can run E85 then i would get as much compression into it as you can.
or go for a 2.3 with 14:1 and run it on methanol... that would be cool. you cant go shaving heads to bump compression easily though dont forget, otherwise your front cover isn't going to fit on without re-drilling a lot of holes...
Simon from simax engineering in parkside is doing a conversion for one of his escorts, he also might be able to help you out with machining front pulleys or whatever..


Gazz

[MK1_Oz]

I spoke to Simon the other day when prepping my car for Classic Adelaide. Might have to have a Duratec chat with him too.

A Cosworth steel crank from the UK is about AUD$3000. The US cranks seem cheap - what is the quality like though?

So how do you change compression on a Duratec then?? Pistons already need pockets so domed pistons wouldnt be an option. Welding the combustion chambers??

Probably thinking 2.3L at the minute. Nobody can tell me a rev limit with a 2.3L standard crank though. Not sure what the limit would be with a steel crank either....

[eric]

You dont have to buy a forged crank the std item will take 8500rpm and pushing out 300hp, if you use Supertech pistons the compression ratio is calculated based off a 0.017" Head Gasket using the std stoke.

P4-DU875-P7 87.50mm (STD) 14.5:1 on 2.3L / 12.5:1 on 2.0L
P4-DU88-P7 88.00mm (+0.5mm Over) 14.1:1 on 2.3L / 12.6:1 on 2.0L

[eric]

The 2.3 does not rev as well as the 2.0 as the stroke is too long, so use the 2.0 or go with a 2.5 and use the 2.3 crank makes 2.4 and the 2.0 high flow head, it will make shit loads of power!

[MK1_Oz]

if you can run E85 then i would get as much compression into it as you can.

Must be 98 octane (I can use race fuels but just cannot afford to) under the regs. My old 2 valve pinto is therefore restricted to about 10.5:1. I know that multi-valve engines can generally go higher in compression before detonation starts but not really sure how high I can go given that I will be on 98RON AND on carbs (therefore without engine management). 12.5:1 has been suggested above.


[QUOTE=eric]
The 2.3 does not rev as well as the 2.0 as the stroke is too long, so use the 2.0 or go with a 2.5 and use the 2.3 crank makes 2.4[\QUOTE]

You say stick with the 2.0L as it will rev better but then also suggest a 2.3 crank in a 2.5L which also would not rev well....confused. I suppose the capacity of the 2.5/2.3 means it wouldn't need to rev as hard.

[eric]

I run over 12.5.1 compression with the std head gasket using the Supertech piston

[eric]

The combo of the 2.3 crank in a 2.5 and the correct rods and slipper piston makes for a short stroke, when my engine needs a refresh this it what I will be doing next

[Forest_rallying]

A 2.3 crank still has the same stroke in a 2.5 block, the only difference must be larger pistons of the 2.5 engine to give a capacity of 2.4. It'll probably give a different rod ratio with having longer rods and bigger bore. I have a set of forged pistons for a 2.5 donor engine I am eventually going to build. I'll have to get a measurement of the piston diameter.

I don't see the point in reving the balls off long stroke engines, they aren't BDAs, it's better to use the torque of the engine and run higher gearing.

[eric]

Some info here that be of use http://www.sbdev.co.uk/New_Products_Duratec.htm