svt heads on 3L block

[98TredSVT]

How many people have done the swap this way? What are the upsides and downsides? It seems to be the easiest swap. Does this combo have the highest compresssion ratio and would it still run well and safely on 93 octane?

I'm talking about just taking my svt 2.5 heads with the cams and the uim and liu and just bolting them on the 3 liter block, there is just a small hole on the 3 liter block that needs to be filled correct?

 

[todras]

So you're going to put old high mileage heads on a low mileage 3L block? Not very smare IMO. If were to do the swap I'd send the heads to get a refresh. xchang, rkneeshaw and I put one in his car years ago and it has a ton of miles on it. He couldn't be happier. Yes, it does have the highest CR. All 3L's should be tuned. Do you have to, no. Should you? Yes.

You also have to grind the crank on the trans. side, alternator ear, and a trans mount off so the svt oil cooler lines clear.

All of this has been posted oh about 7 years ago. LOL! Needs more searching in both old and new forums.

 

[98TredSVT]

wouldn't that throw off the crank's balance?

 

[98TredSVT]

Also I don't see the big deal with my head's mileage, last night I told you it had around 72k on it, and there are people putting turbo kits on 100k+ engines and putting down way more power through them with no rebuilds. Tricker's engine was original when it had like 160k and ran nitrous for two years on it.

 

[todras]

If you're going through all the work of pulling and engine and rebuilding I wouldn't want to throw the $ away when a valve or something goes. It's common sense. People also aren't pulling an engine to put a turbo kit on in most instances. They aren't hurting anything if they have engine issues with it. They know something may happen and will take it as it occurs.

 

[98TredSVT]

ok but I'm still unsure about the crank grinding..... Is their a name the 3L w/2.5 heads goes by that would be easier searching for?

 

[TourDeForce]

ok but I'm still unsure about the crank grinding..... Is their a name the 3L w/2.5 heads goes by that would be easier searching for?

Hybrid.

Check the stickies up top of the forums. Great info there. Will likely answer your questions about the crank grinding. Grinding is done near center of rotation and outside the block so affect on balance is near zero. Nuttin' to worry about IMHO.

A hybrid also requires you transfer your timing components over - not a big deal if you're already gonna transfer the heads. Read, read, read, and you'll avoid surprises and enjoy a great swap.

 

[SHOgoFast]

You say easiest, but pulling the heads and filling the oil drainback may not be that easy. Not to mention you will then have to buy new head studs and gaskets which aint exactly cheap.

Just port it or buy the nautilus LIM. .02

 

[98TredSVT]

I just looked up the prices on napaonline.com. The headgaskets are $70 each and it's $24.39 for each head's bolt set, so it'd be almost $200. If I do go the 3L head route, how do you port the heads without getting metal in the heads? It seems really risky.

 

[Bradness]

Porting the 3.0 heads w/out getting bits of AL internal is pretty simple-use rags or cardboard cutouts & grease and have the motor on an engine stand turned upside down. When you're done, make sure they're spotless internally.

Using split port heads IS NOT the easiest 3.0 conversion but it has the potential for the highest HP/TQ output. There has been much discussion here lately about the pros/cons of the different builds. Using split port 2.5 heads and getting the full potential out of them requires regrinding/replacing the valves & seats. If you're not willing to do that, then this type of build doesn't really make sense.

 

[Big Jim]

Three direct issues to consider. The 2.5 valves are smaller and installing the 3.0 valves into the 2.5 heads increases the cost. You will throw away a lot of ponies if you don't move up to the larger valves. The 2.5 head combustion chamber is smaller in diameter than the cylinder bore. It may not be a huge issue, but the potential is there to complicate tuning as the squish area above the block will tend to promote detonation at the worst and complicate smog tests at best as this area will promote NOX generation. For an engineer that could be an issue. For a private party it could complicate getting through a smog test. The third issue is the compression ratio. That might be a horsepower benefit, but it certainly complicates tuning and limits the future for forced induction.

None of these issues are show stoppers, and consideration can be given to exactly what configuration to use and still have a robust engine with excellent performance.

If I ever do a 3.0 swap, I'm leaning toward using the 3.0 heads with the SVT intakes. It will be less expensive and will provide nearly as much power.

 

[warmonger]

Jim,

There have been quite a few engines that are made with the 2.5L valves and they haven't had an issue with emissions. The only issue I'd see is the extra 5mm radius around the outside edge but with a grinding device the chamber can be chamfered around the outside edge. He can lay the 3.0 gasket on the on the head and trace the circle, then chamfer it until they line up. If he wants to reduce compression he can just continue to machine out some of the 2.5L chamber where the metal overhangs out.

As far as the valves, the intake valves do not really need to be changed out, just some light porting is sufficient. I feel the exhaust valves must be changed out but the porting on the exhaust side is very easy once new seats are installed.
Look to about $200-$300 in headwork if you can port for yourself.

Also, we have been measuring the ovalport cams and they have less left than the SVT cams. More lift means you can get by with the smaller valves if you were running SVT cams.

I would like someone to measure the lobe height from the base of the SE contour/cougar cams and see if they are the same height as SVT or same height as ovalport. I'm guessing they would be the same height as the ovalports.

 

[Big Jim]

I should have mentioned that I would use the SVT cams.

From what I remember, the shop manual for 98 showed the same lift for both the SE and the SVT, just more duration for the SVT. I also think I remember TH telling us long ago that the extra duration was achieved by slightly offsetting the secondary lobe on the cam, that the actual cam profile was identical with the SE, just assembled on the shaft differently so that the primary intake valve opened first, then the secondary intake, then the primary closed, followed by the secondary closing. I've never had an opportunity to take a degree wheel to it to confirm that theory.

One thing I am sure of, based on prior hot rodding experience, is that the Duratec, especially the 3.0, can easily use a hotter cam. Too bad that there isn't much of an offering in this area.