cylinder head modification ideas

[2002SL2mp2dohc]

So I was wondering if anyone knows any good ideas for cylinder head mobs.
Recently my cylinder head cracked (pretty sure since oil in coolant) on my rebuilt engine that swapped from a 2000 saturn sw2 into a 2002 saturn sl1.

When I had engine rebuilt I had 0.50mm off the cylinder head

So I`m wondering what else can I do to make cylinder head better. (I`m aware cams are good place to start but can`t find any other than Gude brand, which I hear the quality is not great. Would like cams tho if anyone know other performance cams)

Also is it possible to put flat faced valve from a 91-93 saturn sl2 into a 2000 saturn sl2 dohc cylinder head.

I`m open to any power gain mods or ideas that involve cylinder head, since I have to swap the cylinder head for different one.

[Saturn Night]

Shaving the head was your first mistake. It retards the camshaft timing for the valves, which will cause power loss, but will help generate peak torque at a lower rpm range.

There are some guides on how to build a Saturn Twin Cam.

Here is the most important aspect: Saturn 1.9L engines are UNDERsquare engines.

The stroke length is greater than the bore diameter.

So, for natural aspiration, you want modifications that will improve flow velocity, primarily.

Now, onto your specific question, about the head.

1991-1993 valves MAY NOT fit in your head. Those valves fit in 1991-1998 cylinder heads, as they were all the same casting, camshafts, ports, etc.

1999-2002 heads are a different casting design, different camshafts, different valves, different designed ports, etc.

However, the 1996-1998 cylinder heads WILL BOLT onto your block. 1991-2002 uses the SAME BLOCK casting(no casting #'s were ever used) for BOTH SOHC & DOHC. Differences are internal parts on both.

Use of the 1996-1998 head will require you to change the timing cover and timing chain set to those years, as well.

You can "port match" the intake/exhaust ports, but do NOT fully port the head for racing.

Having your stock valves machined with a 5-angle design will improve performance, as well.

However, do NOT shave the head for higher compression. If the head is warped more than 0.006", it is scrap.

[2002SL2mp2dohc]

I`m aware that head shaving does that, but the cylinder head was professionally done so there was no errors/imperfection to cause failures (pretty sure cylinder head was just defective.

The main thing I`m looking for is performance parts not what aspects of the cylinder head to improve as I already know that much about how internal combustion engines work. I thank you for the tips and info anyway.

Things that would like to improve and get info

1.(cams) I would to like to know what cams are the best or cam setups or cam mobs.

2.(valves) if i can get performance valves or modify them to boost compression and/or flow

3.(valve springs) high performance valve springs

4.( roller rockers) high performance roller rocker/rockers

Would like any info on what I can do other than listed things as well.
If any performance parts please leave a link to where i can find them or order them from.

Also I`m in Canada so there are parts that I can`t get shipped directly.

[OldNuc]

Buy or build a Mega-Squirt and tune the sock engine for power. That gets you away from mechanical mods. Once you have figured out how to tuned for power without melting the valves then you can go on to performance cams. There really are cams available but a stand alone fully tunable ECU is required.

[Saturn Night]

Originally Posted by 2002SL2mp2dohc

I`m aware that head shaving does that, but the cylinder head was professionally done so there was no errors/imperfection to cause failures (pretty sure cylinder head was just defective.

The main thing I`m looking for is performance parts not what aspects of the cylinder head to improve as I already know that much about how internal combustion engines work. I thank you for the tips and info anyway.

Things that would like to improve and get info

1.(cams) I would to like to know what cams are the best or cam setups or cam mobs.

2.(valves) if i can get performance valves or modify them to boost compression and/or flow

3.(valve springs) high performance valve springs

4.( roller rockers) high performance roller rocker/rockers

Would like any info on what I can do other than listed things as well.
If any performance parts please leave a link to where i can find them or order them from.

Also I`m in Canada so there are parts that I can`t get shipped directly.

Well, if you knew all that already, you wouldn't have had that head shaved. Fine, Mr. Pro. Next time be more specific in your knowledge, instead of asking everyone for their input.

Hope you made sure to shave that timing cover, to match that head, but you knew that too already.

[Saturn Night]

Originally Posted by 2002SL2mp2dohc

I`m open to any power gain mods or ideas that involve cylinder head, since I have to swap the cylinder head for different one.

****Until your suggestions don't require him to spend a bunch of money on his 1.9L, to brag to all his friends about***

That is YOUR quote, by the way.

Ironically, you are pricing amd researching aftermarket camshafts, when most racing Saturn builds just swap the exhaust cam for a stock intake cam, which shifts to peak HP rpm near the 7,000 range for half the cost, or less, than buying an aftermarket cam that does the same thing.

Both still require a Megasquirt, and both still REQUIRE the bottom end to be built for handling 7,000+rpms. The stock cranks will only hold up, until about 6,750rpm(which is where fuel cut-off is programmed on the stock PCM), but I know you knew all that, already too......

You can probably tell me all about average piston speeds and how piston "stretch" occurs at higher rpms, or how valve shrouding occurs in smaller bore engines with cams that have too much lift, because you know all about how internal combustion engines work, hence why you wound up with a cracked head that you haven't confirmed, but are "pretty sure" because you have oil in your coolant.....

You probably knew you needed a larger bore throttle body and a better designed intake, if you run hotter cams as well, since you already knew the stock plastic manifold only makes power up to 5,600rpms, as opposed to the older aluminum intakes(which had longer runners) were good for up to 6,200rpms......

[Medtactics]

With such a long stroke, rally type mods I feel are the way to go, going for mid-range power, 2.5k-5.5k RPM. 6k RPM on the LL0 is about the equivalent of a typical perf spec Honda motor @ 8-8.5k RPM. That is, in terms of piston speeds.

If anything, a custom recast of the head with much better designs that can't be accomplished on a mass production scale. Extremely expensive most likely, but the gains would be unreal using modern science of engine building. But again, extremely expensive as custom intake and exhaust would also need to be fabricated.

At that point the LTG Ecotec and the ever rare and elusive opel F40 transmission would be a much better route, unless you want something never before seen.

[Saturn Night]

Originally Posted by Medtactics

With such a long stroke, rally type mods I feel are the way to go, going for mid-range power, 2.5k-5.5k RPM. 6k RPM on the LL0 is about the equivalent of a typical perf spec Honda motor @ 8-8.5k RPM. That is, in terms of piston speeds.

If anything, a custom recast of the head with much better designs that can't be accomplished on a mass production scale. Extremely expensive most likely, but the gains would be unreal using modern science of engine building. But again, extremely expensive as custom intake and exhaust would also need to be fabricated.

At that point the LTG Ecotec and the ever rare and elusive opel F40 transmission would be a much better route, unless you want something never before seen.

He'll certainly see a snapped timing chain, if he were to drop in an Ecotec.......

[Medtactics]

You know I referenced the 3rd Gen block right? LTG? 2.0L? The block that put out 1500HP (limited via ECU side, made more than that though) with over a 100 documented runs and more afterwords with no downtimes?

We are talking about the same block version right? Not the early design?

[2002SL2mp2dohc]

I would like to give apologies to saturn night,I didn't want to offended you, nor had Iwant have offended.
The main goal looking for is just simple mods and power gain tricks.
Also I`m not racer bragging up my friends guy at all and I take serous offense to that just cuase I`m young like wtf is with people and stereotypes, but I`ll let since my poor wording started this.

[fdryer]

0.50 mm is 0.01968503937 inch. 0.0196" isn't much, perhaps a single or double pass of a flywheel cutter on a Bridgeport milling machine? Just enough to clean up and resurface a cylinder head? If an increase in compression was desired, this is one way to go and any spark timing changes is adjusted on the fly relative to the knock sensor telling the PCM that pre-detonation is occurring, if any does occur, with the pcm automatically retarding spark timing until knock goes away. With EFI systems, spark timing is automatically adjusted and always tries to bring timing back to where it's ideal, faster than anyone can figure out since it's all electronically controlled. With so little head shaving, an engine dyno would have to be used to determine if there are any gains in power or just restoring lost power.

[OldNuc]

Machining the head or block beyond the nominal amounts required to provide a flat sealing surface will end up retarding the mechanical timing when using stock components beyond any PCM compensation range. There is little to nothing to gain by milling the head with this engine.

[Saturn Night]

Originally Posted by Medtactics

You know I referenced the 3rd Gen block right? LTG? 2.0L? The block that put out 1500HP (limited via ECU side, made more than that though) with over a 100 documented runs and more afterwords with no downtimes?

We are talking about the same block version right? Not the early design?

The block and the timing chain are apples to oranges, though.

The issue with Scrap-O-Tec boat anchors amd the snapped timing chains come from the oil hole being drilled too small, causing oil flow to be too low at idle, causing excessive wear on the chain.

The block you are referencing come from the turbocharged/supercharged issues or cracked cylinder blocks, that were typically replaced on older Cobalts as the older blocks couldn't make it more than 40-50k miles before they cracked.

You can have a solid block, and still have a poorly-designed timing chain system.

Old Chrysler 318 V-8s are a prime example of this. The engine, itself, was rock solid. The timing chain, around the late 1970s-early 1980s was failure prone. Once that issue was revised by Chrysler, the 318 became one of the best damn engines they ever produced.

[Saturn Night]

Originally Posted by fdryer

0.50 mm is 0.01968503937 inch. 0.0196" isn't much, perhaps a single or double pass of a flywheel cutter on a Bridgeport milling machine? Just enough to clean up and resurface a cylinder head? If an increase in compression was desired, this is one way to go and any spark timing changes is adjusted on the fly relative to the knock sensor telling the PCM that pre-detonation is occurring, if any does occur, with the pcm automatically retarding spark timing until knock goes away. With EFI systems, spark timing is automatically adjusted and always tries to bring timing back to where it's ideal, faster than anyone can figure out since it's all electronically controlled. With so little head shaving, an engine dyno would have to be used to determine if there are any gains in power or just restoring lost power.

Call a machine shop, and they will usually suggest milling a warped/pitted head about 0.010".

Buying remanufactured heads are typically shaved 0.010" as SOP, similar to the SOP of boring the blocks on reman engines @ 0.030" and installing oversized pistons/rings.

Even shaving a SBC head .020" requires the intake manifolds to be milled down as well, because the gaskets no longer seal properly and the bolts will not line up correctly.

What looks "minimal" to us, is actually a LOT when it comes to an engine because they require precise tolerances and design for optimal operation.

Shaving a head .020-.030" can make a BIG difference in the durability of the head, since there is thinner metal, which has less capabilities to resist thermal expansion(less molecular structure/less total metallic mass).

And with a machined head, it is a double whammy. The compression is increased, which increases combustion temperatures and pressure, while you have less structural mass trying to keep it contained.

There are no FSM SOP tolerance for shaving the Saturn 1.9L cylinder heads, for cleaning up a warped or pitted head.

Tolerance to junk, per FSM is 0.006" for BOTH the block and head. If either are showing signs of warpage beyond that tolerance, they are to be replaced with a new head/block.

The cylinder heads can still be ordered, through GM, for some S-Series. Some are discontinued.

All cylinder blocks have been discontinued.

If your block is warped, at its deck, then you will want to source a used block, a core engine, or a used engine that runs. Same goes for the discontinued cylinder heads.

Reman head warranties aren't worth the paper they are printed on.

[2002SL2mp2dohc]

Yeah I only did head that way cause of a site that I found, grassrootsmotorsports.com/articles/different-kind-race-car/[/url]
Although got to give thanks to fdyer for the heads up on the knock sensor, which brings to quick question, would taking 0.50mm also affect the crank shaft position sensor?

I very interested in the intake cam used as exhaust cam, can someone post a link or maybe how to video.

[fdryer]

No thanks necessary. EFI systems can be confusing to anyone not familiar with basic four stroke engine fundamentals then adding sensors to make EFI systems magic. Add electronics and more unfamiliarity with how sensors work and how the EFI and engine system suffers when a sensor fails and you have strange new symptoms. One last ingredient to this mix, catalytic converters and programmed emissions controls makes business for repair shops and dealers with the aftermarket selling millions of readers and scantools. Old school meets new school with a whole new set of mechanics and technicians more knowledge about electronics (supposedly).

Since the machined teeth on crankshafts are permanent with crank sensors fixed in their location, crank signals remain unchanged. No concern for any such thing as advanced or retarded timing signals. The ECM or PCM relies on the crank sensor for its steady and precise timing signals - it provides the electronic clock in order for the ECM/PCM to operate the entire EFI system. No clock signal no EFI system operation.

[2002SL2mp2dohc]

So shaving cylinder .50mm and intake cam in place of exhuast cam would require a performance PCM or will the stock do fine.

Okay so things I'm going to try unless there's something I should know that may prevent future problems mainly electrically.

1. Shaving head .50mm

2. Intake cam to replace exhuast cam

3. Port match exhuast and intake ports (not porting to race specs)

4. 5 angle valve job

[Saturn Night]

If you want higher compression, use flat-faced valves from the 1991-1993 DOHC(if they will fit). This will provide a 0.3:1 bump in static compression, which will allow you to still use pump gas(recommended Premium 91 octane or higher).

10.0:1-10.5:1 compression CAN run on 93 octane, if you like replacing cracked heads, burnt valves, and head gaskets about every 80,000 miles.

Adding the intake cam on your exhaust side will likely get you all kinds of DTCs on the stock PCM. The PCM is programmed to run with fuel maps for the stock cam timing, lift, duration, and overlap.

When changing the camshaft profile, you also nominally can change your static compression ratio as well(as there is a greater CFM of air entering/leaving the engine within the same size area of the combustion chamber).

The stock camshafts are good up to 6,200rpm and are a "Street/Strip"(Stage 2) profile, that are typically rated from 1,500-6,500rpms.

Adding higher lift and duration to the exhaust side will shift your peak torque and peak HP close to the 7,000rpm range(about 5,500rpm for torque). This will make the idle quality drop(from reduced vacuum signal), and will kill a lot of the low-rpm torque for takeoffs that is not easily countered with the short ratio transmission.

Team ScR tired to shave their head, and retimed their camshafts, and their race car was still pulling a 15.8 in the ¼-mile. A STOCK Twin Cam w/5-speed can do that in a ¼-mile.

There are guys, on the SaturnSpot website, running high 14s, with bolt-ons and a 5-speed.

[2002SL2mp2dohc]

So I decided on getting a new/re manufactured cylinder head and was wondering what the best/strongest head manufacturer is. mostly looking for a stronger casting or most reliable re manufacturer. Ive also decide just to put the head in stock no fancy stuff so to speak.
Tho info is good since I might build another Saturn down the road.

I also would like to ask is the valve pan from 91 interchangeable with a 2000 valve pan, and on top of that all of the spark plugs Ive tried burn up I think term is. (basically I got orange/burn coloring on the ceramic part of spark plug just above the metal part) and wondering what might be a good spark plug or possibly input on reasons why its happening.

Ive got ACCEL coil pack on stock ICM and fairly new spark plug wires

Brands of spark plugs Ive used (both coils)

NGK recommend ones from a forum (current)

Bosch all different types (ran fine but burnt up in the end)

Energizer E3 (worst ones) never again lasted less than 1 month (stock coils when used)

Can`t remember the rest will post them later if I remember them.

[Saturn Night]

Originally Posted by 2002SL2mp2dohc

So I decided on getting a new/re manufactured cylinder head and was wondering what the best/strongest head manufacturer is. mostly looking for a stronger casting or most reliable re manufacturer. Ive also decide just to put the head in stock no fancy stuff so to speak.
Tho info is good since I might build another Saturn down the road.

I also would like to ask is the valve pan from 91 interchangeable with a 2000 valve pan, and on top of that all of the spark plugs Ive tried burn up I think term is. (basically I got orange/burn coloring on the ceramic part of spark plug just above the metal part) and wondering what might be a good spark plug or possibly input on reasons why its happening.

Ive got ACCEL coil pack on stock ICM and fairly new spark plug wires

Brands of spark plugs Ive used (both coils)

NGK recommend ones from a forum (current)

Bosch all different types (ran fine but burnt up in the end)

Energizer E3 (worst ones) never again lasted less than 1 month (stock coils when used)

Can`t remember the rest will post them later if I remember them.

If you are seeing orange-yellow buildup on the plugs, this is indicative of "high-speed glazing". High speed glazing occurs, when combustion temperatures are rising too quickly under hard acceleration periods(which happens because the EGR is programmed to be closed under WOT). The effects will burn and round-off the tip of the plug, reduce performance and plug life.

Basically, your plugs are too hot. You will want to look for a "colder" plug(which deflects more heat energy of combustion AWAY from the plug).

NGK males a colder, copper plug that is best suited for use in the Saturn 1.9L.

I also have the Accel coils, Granatelli 0-ohm wires and E3 Diamond Fires in my engine. They lasted only 15,000 miles and are due to be replaced, because they burn too hot. Give me a second to search for the NGK part number.