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Marius850R

Upgrade N/A Cams , Only Intake Cam Or Upgrade Both Int/Ex On My 850 T5-R

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Yeah I have been messing with the same crappy old JY motor this whole time I've just damaged it and repaired it a couple times. lol. I am going to disassemble it as I want to verify a few things. I want to see how the rods, bearings, and pistons look, and how the cam journals etc look with the frankenstein cam setup.

This data might be helpful when it comes to assembling and tuning the "new" motor

The new motor is a T6?

On the cam front, you used a matched pair of 960 (NA) cams, or was one T6?

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Yeah new motor will be another T6. I want the later head/cooling and manual tbelt tensioner etc, so it's easier to stuff rods in a low mileage '00-'01 motor than refurb this crusty old '99.

Yeah I used a matched pair intake an exhaust of early 960 cams for 9mm of lift. vs. the T6's 7mm of lift. NA FWD cams are 8mm or 8.5mm I think. So it's a bonus for a 6 cylinder app to have the early 960 cams as an option.

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Question. Since I didn't line up the timing marks on sprockets before I took off my last timing belt, am I risking anything removing the valve cover and then cams with everything not at TDC (which I know isn't exactly top dead center, it's with those little grooves on the cover)?

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Question. Since I didn't line up the timing marks on sprockets before I took off my last timing belt, am I risking anything removing the valve cover and then cams with everything not at TDC (which I know isn't exactly top dead center, it's with those little grooves on the cover)?

What exactly are you asking?

Before you remove the cams, you need the motor set to TDC on the crank gear/cover markings. When the cams are installed, you need the Volvo tool or, a suitable substitute.

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What exactly are you asking?

Before you remove the cams, you need the motor set to TDC on the crank gear/cover markings. When the cams are installed, you need the Volvo tool or, a suitable substitute.

OK, that's what I was asking. And the guy that made the cam locking tool that I posted a pic of on here is going to send me that one, so I'll have some extra security when swapping cams.

Thanks.

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OK, that's what I was asking. And the guy that made the cam locking tool that I posted a pic of on here is going to send me that one, so I'll have some extra security when swapping cams.

Thanks.

I've read several people's posts who have done cam swaps without a cam locking tool - it's NOT required. If you're careful, the cams won't move. I'm just saying, sure it's nice to have, but you can do the job without it. ;)

PS...I'm installing N/A cams this week. Head is currently at the machine shop. :lol:

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I've read several people's posts who have done cam swaps without a cam locking tool - it's NOT required. If you're careful, the cams won't move. I'm just saying, sure it's nice to have, but you can do the job without it. ;)

PS...I'm installing N/A cams this week. Head is currently at the machine shop. :lol:

Of course you can do it without. But, it's hardly something to recommend to someone who hasn't done the job before & doesn't have the thing down.

It's foolish to risk bending valves, or just ending up with f'kd cam timing.

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I have no problem taking my sweet ass time and doing it without the cam lock tool, but I agree that it being my first time, I should take some precautions. When I get into it I'll see what I'm up against, and if I feel that I don't need the cam lock tool, I probably won't use it, but if I feel like I need it to do the job right, I'll throw it on, either way, I'll be ready.

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Just remember, the most frustrating part of doing it without the cam holding tool will be when you release the tensioner and it tightens the belt revealing that one cam is actually a tooth off. Then you have to remove the tensioner and do it all over again ;) It is not as simple to do it without the cam locking tool. But if you are careful it shouldn't be a problem. Don't get all upset if you mess up the timing by a tooth or so though, just do it again.

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Cool, thanks. I'll definitely take my time. It's obviously my first time doing it, so I know I can't get too worked up doing it.

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Guys, the stock turbo cams are very anemic.

The NA cams are slightly less anemic, though they do have a good amount more lift. It's a no brainer. They are better, period.

Whether it is worth it to do them in your car depends on your confidence, skill level, schedule, horoscope for the day, etc. It's no more difficult than doing a timing belt IMO. Actually, it's easier IMO.

Hussein, you are a saint for encouraging people to do it the right way.

However, I have had the cam cover and timing belt off about a jillion times in these cars, and never used any of the special Volvo tools. I pull the valve cover off when the engine is all lined up on TDC, then it just takes a quick visual check that the crankshaft is still lined up, re-installing the cams and the cover, compressing and installing the tensioner, making sure the gears are on the right teeth so when the belt re-tensions they will be pulled to their TDC marks, and that's it.

I have *never* stripped the threads in a cam cover bolt when reinstalling the cover. It is tedious, and you absolutely have to do it carefully, but as long as you tighten a center 6-8 or so bolts just a turn or so at a time by hand until the cover is snug against the head, you'll be fine.

I think I could do the cam swap in about an hour's time. I would get a chance to test this estimate, but I think I'm going to do my timing belt and water pump at the same time.

As far as before-after numbers... I have a pretty good setup to show significant gains, but it's also a setup that everyone will probably dismiss the results in discussions as I'm "heavily modded" (whatever that means :rolleyes: ).

The bottom line is the cams are meaningfully more aggressive, and as long as you can optimize the cam timing for your intended powerband and tune, you will see gains. In my opinion people being wishy-washy about their confidence in doing the swap is why we see sooooo many of these annoying threads and nobody actually doing anything. If anyone wants a hold-the-baby's-hand walkthrough on doing the cam swap with hand tools, I'll write one up. Until then, everyone stop pretending like nobody knows if they're actually better or not. They are.

I disagree with your blanket statement of "Moar is Better"

The first and most simple to understand is "Overlap". On a turbocharged car "Overlap" beyond a very small amount will reduce your engines effectiveness. As air enters the cylinder on a turbocharged car its being pushed in via the turbocharger. This means we don't have to worry about "Cylinder filling, RPM and Lag of a N/A engine" However, we do have to worry about overlap because as air enters the engine the more overlap we have the more air we are simply pushing out the exhaust side. This air is obviously just being wasted and because 90% of the people on this forum have very small turbochargers you can't afford this waste.

(Note, I am generalizing here there becomes a point were this gets far more complicated and I don't want to take it any further)

With a larger turbo run the intake cam only or go aftermarket.

I have alot more I can say on the topic but to be totally honest I don't really care.

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With a larger turbo run the intake cam only or go aftermarket.

Some people have said to run only the exhaust cam, what's the difference here? Or if you do run both cams, do you have a suggestion as to what the timing should be on them, either for an overall gain, or more so low end?

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I don't know how much air you're going to be pushing out the exhaust side with the high exhaust manifold pressure from such restrictive manifolds/turbines. If anything, you're going to get more reversion. This is probably what kills a lot of the engines on here... exhaust gas goes back into the chamber, things get too hot and detonation starts. Not to mention the small compressors are usually out of their efficiency range, adding to the heat.

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I don't know how much air you're going to be pushing out the exhaust side with the high exhaust manifold pressure from such restrictive manifolds/turbines. If anything, you're going to get more reversion. This is probably what kills a lot of the engines on here... exhaust gas goes back into the chamber, things get too hot and detonation starts. Not to mention the small compressors are usually out of their efficiency range, adding to the heat.

Exhaust can't go back into the chamber because its getting forced out. Also, remember the turbocharger is getting pressed on by the exhaust gas but it also makes it a one way trip for exhaust flow.

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In my experience more overlap in a stock or lightly modified car is not undesirable because of filling losses but rather from reversion.

The pressure in the ex manifold is higher than the pressure in the intake manifold so exhaust reverts back into the cylinder effectively creating EGR anytime there is overlap.

Moderate to heavily modified turbo engines have greatly reduce ex to intake manifold pressure differential (commonly referred to as EBR or exhaust back pressure ratio). This comes from higher flowing exhaust, freer flowing intake, larger turbine wheels, etc..

As the EBR gets closer to 1:1 more overlap can be used as the intake manifold pressure is not 'over powered' by the ex manifold pressure and cylinder back filling is minimal. This means some overlap can actually contribute to dynamic cylinder filling since the engine's fluid dynamics start to behave more like a NA system, that being small amount of exhaust back pressure relative to the manifold pressure.

Consider the following example in a modified turbo engine at WOT. Ex manifold pressure is 16 psi, and intake manifold is 14 psi. The pressure relative to atmospheric has little bearing on the equation because it is the relative differential that is important. The example here is somewhat like an N/A engine at WOT where you have atmospheric pressure in the intake manifold (14.7 absolute) and 2 psi back pressure in the exhaust (16.7 absolute). The same differential in pressure as the turbo example. Granted flow does certainly change with a pressure change but I'm only showing the correlation between the two, not an exact match. Point being, the more modified the engine the more overlap you may find helpful for increased power.

Each situation is different but the real answer is gather data. What is your engine EBR? Then you can make a proper selection on advance or overlap. Tap a line to the EGR port or manifold and run it to a boost gauge, compare it to the intake manifold boost gauge. You'll be surprised what you find. In some situations you can get what the bonneville guys call cross over, where the ex manifold pressure is lower than the intake manifold pressure, this is the holy grail of engine tuning and represents where the engine is running at it's peak VE.

For what it's worth my 18T setup (at it's worst point) has 20psi ex manifold pressure when the intake is at 14.7 psi (1.36 EBR, at best it's 1.28 EBR). That's with turbo back, intake, and angle flange 18T, stage 1 tune. car is otherwise stock.

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