Contour Enthusiasts Group Archives Forums Modifications Duratec Performance balancing, boring, headwork, etc.

Trolled around but haven't seen anything mentioned about the above being done. My experience with a newer 5.0 (w/MAF) was that head work (3 angle job, mild porting/matching) and partial balancing netted at least 1/2 sec better 0-60 (was done at 30k mi.). That translated into lotsa ponies. Nothing else was changed and the EEC handled everything better. Very cheaply done, too. I was wondering if porting/polishing/balancing etc would be beneficial to a 2.5? I know the extrude honing helped...is it worth it to take it further? I have 41k on the motor and am between trading it or keeping it for a few yrs. at least. A teardown would seem like a good idea if I'm going to keep it for a few yrs, and as long as it's apart, anything else b'sides a new water pump?....sorry if I ramble. I would prefer to keep this car and wouldn't mind having it torn down first, all things considered. Anyone ever toyed with increasing displacement or compression ratio (on stock block)? Seems like an SVT V6 is a candidate, perhaps....everything I thought of is still a lot cheaper that t/c or s/c and better for a motor w/41k on the clock already methinks.

I'm sure that it would help, but it is a lot of work to get the heads off. Not nearly as easy as on an old 302 with overhead valves.

Well, I guess everything would be fun, from the heads on down. I get nervous about alum engines and the inserts, sleeves, bearings, etc. I guess nobody has worked the Duratec that way yet. A FWD car kinda makes tinkering with internals a lot more interesting, true. I have to hand it to Ford on this one, it's hard to improve on a tuned engine (esp the great intake!). But I wonder if higher compression or more cc's wouldn't get another dozen+ HP at least, esp with proper balancing. Maybe I'm fishing for deer here, lemme know. I would rather tear down a motor at 50k and make it worth another 50 than watch it fail in a catastrophic way at 80k. The 2.5 is a great plant, and nobody offers heads better than what the SVT's came with. Darn. It's easier to bolt on heads than to get into the guts! Maybe I should bolt a 4cyl into the trunk and put an Auburn diff on the rear wheels...hehe. No, wait, I still need to replace the water pump, right?

A good port and polish in the heads may or may not net a few ponies, and is worth a try, thouh the heads are alrady pretty good. One thing may be to have larger valves put in the stock heads (valves from a 3L Duratech)
As far increasing displacement, there is no easy way to stroke the crank, so that is kinda out, and the stock 2.5L block won't take any overboring without new liners, which is not an easy tihng to do either. The choice way to increase displacement lately is using a 3L duratec block from a taurus or escape (or other applications) and going from there; check out the 3L Forum for some more info on the swap. Higher compression could help, but it brings with it a host of tuning issues, as the stock CR is pretty high already. My ideal setup in a contour? a 3L long block (the 3L has larger valves compared to the 2.5L), extrude hone the intake and exhaust ports, run SVT cams, (or ST220 or custom, if you can find them) and a heavily extrude honed intake manifold (or a larger custom unit that will fit under the hood) then of course because of how I am, I would want to add a turbo

As far as the stock heads on a 5L, yeah, they are far from perfect, and can greatly benefit from a good port job.

Head work can account for quite a few HP when it's done right, problem is to get the heads off on this engine, you have to tear it down quite a bit. Once that far, it's only a handful of bolts ad the whole engine is out.

Can't bore the sleaves easily or they'll pop, destroying the block in the process. Best option is to get a 3 liter block if you want more cubes (see 3 liter forum).

Balance and blueprint won't do a whole lot on these engines as they are already held to quite tight tollerances from the factory. Money is better spent elsewhere.

If you want to stick to the 2.5, you can swap over the the larger intake valves from the 3 liter heads. You might also be able to use the old 2.5 intake valves as new exhaust valves, but this may not be able to be done, depending on the metalic composision of the intake valves vs. the exhaust valves. i.e., valve meltdown...

EDIT Oops, Rara beat me to it... Ya, what he said...

[QUOTE]Originally posted by jaxter:
"... I guess nobody has worked the Duratec that way yet. "
I've done several of those things that are listed above, and I believe it made a difference.

warmonger

head work can be a beneficial thing. I would recommend geting it flow tested at each step. If you Do try to go the 3.0L valve install, after you take the head to get the seats cut for the new valves, , THAT is when you would want to do some portig work(make the tansition from cast to machined parts smoother). Also might want to look at mathcing the ports to the intake(I don't rmember which SVT's came with the larger lower intakes... might want to look into that)andworking on the radii of the intake and exhaust ports(not sure the head s on the SVT, but on a regular big block, its lookng at the short turn radius that yields you a big improvement in flow.)
Whatever you do.. BE sure to get some FLOW bench number of before, and dureing each stage so you can see where you gained the flow increase, or where it did not affect it at all... BE SCIENTIFIC, and ALOT more people here will be more.. hmmmm.. understanding.. no...more... no wait.. less likely to give your results a big fat bronx cheer...(right Demon... ) LOL

Good luck!