From the Allpar Chrysler website:

Allpar (Chrysler, Dodge, Plymouth, etc. enthusiast site)

Chrysler, Dodge, and Plymouth 3.3, 3.5, 3.8 Liter V-6 Engines


by Michael A. Cole except where noted

Introduced in 1990, the 3.3L was the first Mopar designed and built V6 engine to see duty in front wheel drive Chrysler vehicles. [A 3.9 liter engine, based on the venerable LA series V8s, was the first Chrysler made V6, but it only saw truck duty.]

Joined by a 3.8L version the following year, the 3.3/3.8L series features a traditional cast-iron block, aluminum head, overhead-valve design while also incorporating newer technologies such as sequential, multiple-port fuel injection (SMPI) and an integrated electronic ignition system supplanting the mechanical distributor, rotor and coil systems of the past.

3.5 liter V6Also in the 3.3/3.8L series, a 3.5L aluminum-block version saw early duty in the LH platform series. It was later replaced by an all-aluminum 24-valve 3.2L V6 featuring a unique (at the time) coil-over-plug design which eliminated the need for secondary ignition cables.

With ample torque available early in the rpm range, the 3.3/3.8L series was well suited to its primary application as a source of power for Chrysler's award winning minivans. These engines were also used in the Dynasty, New Yorker, Fifth Avenue and Imperial models until those vehicles were later replaced by the LH platform series, which was eventually powered by the aforementioned all-aluminum 2.7/3.2L V6s.

History of the 3.3

[Name of writer withheld]

To start with, us motor room mechanics were a little disappointed when [the engineer] came down with the first prototype parts for the 3.3. We were expecting an overhead cam-high tech-high performance engine, and were shocked when we pulled out a bag containing push rods!

Apparently, somebody did a survey of potential customers and decided that the customer was too dumb to know what was under the hood anyway, so the "cost effective" approach was taken. Ford's 3.0 Taurus engines and GM's 3.8 used pushrods, so why not us?

3.3 liter chrysler engine in lh large car

We were paying a high premium for Mitsubishi's 3.0L V6, and Trenton Engine had the room for another assembly line, so it was a no brainer as far as the necessity and where it would be built. We had some problems early on with valve stem finish which was quickly fixed, a bigger problem was thrust bearing failure. We were getting some engines coming in to tear down with incredible end play, you didn't need a dial micrometer to know which ones were bad. Our manager grabbed me and 3 other mechanics and we spent the next 2 days at Detroit Metro Airport checking crank end play on Snappy rental cars with the 3.3 engine. Most were okay, but an occasional one would produce not 3 or 4 or 5 thousandths end play, but 100+ ! The blame was aimed at the transmission, but we immediately went to a wider thrust face. Has not been a problem since.

I had a real battle with an engineer in regards to the head bolt washers and the ensuing CYI approach he took to, well, cover his [snip]. The 2.2 and 3.3 used the same head bolts and washers; a decision was made to widen the head bolt washer to increase the clamping area. Only problem with this was that on the 3.3, the wider washer could hit the valve spring that is next to the oil feed cam tower. And they did.

[One engineer] told me that noisy tappet replacement was our fifth biggest warranty item on the 3.3, but when they got the suspect parts back to engineering, they weren't noisy. I fought to get a service bulletin written on this, to check for interference before doing a costly cam/tappet replacement, but another engineer [tried to cover up with] the claim that it "helped attenuate" engine noise. On a visit to Trenton Engine, I found the line worker who assembled the heads and asked him why he didn't notify engineering about this. "I did, but was told not to worry about it" he replied...

Another problem is oil leaks. Anytime you bolt aluminum to iron, the gasket in between is compromised, due to the expansion differences between the two metals. This is particularly evident in the chain case module gasket. The gasket moves over time and creates a gap just above the oil pan rail, and boy does it make a mess. Lower intake gaskets leak in the corners. An upgraded gasket was designed with longer, tapered rubber ends that was supposed to end the use of RTV, but RTV will always be a necessity on that application.

Jim Gathmann wrote: The early years of the 3.3 did have problems with the rockers and the oiling system. I did not know when it was corrected... Apparently they fixed this by the second year of production.

"91redbaron" wrote: The 3.5 had a rather interesting intake setup. There were two separate intake manifolds for the left and right side cylinders with their own throttle-bodies (interesting throttle linkage and cabling there). So in a way it was like two in-line 3-cylinders that were joined at the crank.

3.3/3.8L Engine Chronology

The 3.3/3.8 are the only remaining Iaccoca-era power plants still seeing active duty [the ancient AMC straight-six and 360 V8 both precede Iaccoca...and both will be gone before the 3.3]. Now entering their second decade of service, the 3.3/3.8L series has been continuously revised with the 3.3L gaining 33 hp and the 3.8L gaining a healthy 65 hp since inception. (They are currently only available in minivans.)

Engine Years Used Horsepower (bhp) Torque (lb-ft) Notes
3.3L 1990-1993 150 @ 4800 RPM 180 @ 3600 RPM Introduced in 1990. A 147hp version is used in Dynasty and New Yorker.
3.8L 1991-1993 150 @ 4400 RPM 213 @ 3600 RPM Introduced in 1991. Used in Fifth Avenue and Imperial models.
3.3L 1994-1995 162 @ 4800 RPM 194 @ 3600 RPM 3.3L receives power increases for 1994 via revised intake plenum.
3.8L 1994-1995 162 @ 4400 RPM 213 @ 3600 RPM 3.8L receives horsepower increase for 1994 via revised intake plenum. No longer used in cars.
3.3L 1996-2000 158 @ 4850 RPM 203 @ 3250 RPM 3.3L has revised intake and exhaust for enhanced torque. Horsepower drops slightly but torque increases and peaks earlier in the rpm range.
3.8L 1996-1997 166 @ 4300 RPM 227 @ 3100 RPM 3.8L features revised intake and exhaust systems for enhanced power & torque.
3.8L 1998-2000 180 @ 4300 RPM 240 @ 3100 RPM 3.8L receives a significant boost in horsepower and torque ratings for the 1998 model year.
3.3L 2001-on 180 @ 5000 RPM 210 @ 4000 RPM Both are extensively revised for 2001 with new variable intake system and higher compression ratio - but are no longer used in cars.
3.8L 2001-on 215 @ 5000 RPM 245 @ 4000 RPM

Jim Gathmann added:

There are three basic eras which produce different levels of power. The early units (1990-1993 or so) were pretty good, decent.. not something I'd stick in a Super Bee, but in the case of heavy models (which got the two engines), and models designed with towing in mind (minivans) they were pretty good indeed.

In 1994/1995 the HP jumped a good 10-12 HP. This is due to two things: change in the intake manifold design, change in fuel injection system. This is of slight noticeable increase in power from the stock 3.3/3.8.

However the recent models have much more power... these newer versions are almost whole new engines... new intake manifolds, electronics, compression ratio, etc.

Tranny and block has been pretty constant. The tranny (41te?) of the newer models is just a newer A604.. now the newer models work much better (due to electronics differences, internal differences- better material mostly... basically a good rebuild of the older A604 will bring it up to about current 41TE standards...).

In terms of the 3.3 Dynasty (of the later years- 1992, 1993), the 3.3 (stock) isn't that bad. It can do 55-65 (highway speeds) without much work, and certainly can move a heavier car. In terms of from stop to go, I've played around with using 3 or the 4 gears.. in either case, the low end torque of the 3.3 is really not bad (good enough for me to see it as a performance engine- despite what some of the 3.0 guys may say.. there is a reason why the 3.3 was used as a model for making the 3.5....).

The 3.8 New Yorker/Imperials is slightly more powerful and are much better from dead stop (idle) to highway speeds. The local ricers try to hide from the 3.8s as they are surprised by the power of a stock, heavy car....

In terms of changes, most of the changes to the 3.3/3.8 were electronic (however the mechanics did change slightly... the rocker breakage problem was fixed by a design change in late 1991....) in the later years, while up through the late 90s it mechanically oriented- mostly different intake manifolds and such.

But in terms of trannies, you are stuck with the A604/41te as the 3.3/3.8 requires a bell housing that only specific A604s got. Basically the A604's bell housing was changed so it can work on the 3.3- a 3.0 A604 will not work on a 3.3. Now it may be possible to get a 3.0 and 3.3 A604 and note the differences, and duplicate the differences for a 3 spd, etc.

[Paul wrote: The 3.3 / 3.8 do share the same bolt pattern for the transmission as the 3.0.. What differs is the cut out in the bell housing for the 3.0, as the water tube from the water pump comes out under the intake at the top section of the bell housing.]

The 3.5 liter engine according to Chrysler

When introduced in 1993, the 3.5 was the most powerful, naturally-aspirated engine available in any Chrysler-built sedan, with peak horsepower of 214 at 5,800 rpm and 221 foot pounds of torque at 2,800 rpm (it would eventually go to over 250 horsepower).

Developed exclusively for the LH models, the 3.5-liter V-6 incorporates features designed to ensure superior power, quiet, smooth operation, as well as problem-free durability. Additionally, mechanical noise levels are the lowest of any engine ever measured by Chrysler.

Like other major componentry and systems on LH, the 3.5-liter engine was designed to meet or exceed the powerplant Chrysler engineers considered the best in this segment -- the 3.2-liter 24- valve engine that powers Acura Legend.

Nestled in a compact, 60-degree block of cast iron with"over square" bore and stroke, Chrysler's 3.5-liter engine has the highest compression ratio -- 1 0.4:1 -- of any Chrysler-built engine in recent memory.

Numbered among its unique features its electronic fuel injection system uses bottom-feed injectors, the first industry application of this technique in a high-volume passenger car. The limited-production 1 993 Dodge Viper sports car, introduced last spring, also has bottom-feed fuel injection.

'This truly is a premium engine and as 'bullet proof' as we could make it," ventured Howard B. Padgham, executive engineer -- Powertrain Engineering for Chrysler's Large Car Platform Team."At this stage, I'm more confident about the 3.5 than any engine 'ye ever been involved with."

And Padgham speaks from a professional resume of 28 years in Chrysler Engineering, 1 5 of those years devoted to engine programs, including Chrysler's 1 .6-liter 1 .7, 2.2, 2.2 Turbo and 2.5 four- cylinder engines, as well as the 31 8 CID V-8 and the 360 CID V-8 special, high-performance"police" engine package.

'The 3.5 has the basic ingredients you'd expect from a premium engine," said Padgham,"... forged crankshaft, free-floating piston pins ... those sorts of things."

LH's trend-setting Cab Forward exterior design presented challenges, but no insurmountable obstacles to the 3.5 engine development.

"It's sloped like the hood to fit just like a hand in the underside of a glove," mused Padgham. "Notice the shape of the cylinder head, the design of the intake manifold. They reflect the space we had to work with."

The"north-south" powertrain layout permitted more space flexibility in the engine compartment and, in addition, provides the option of easy adaptation for potential, future applications to rear-wheel or all-wheel drive.

The 3.5's bottom-feed fuel injection system has a three-fold rationale, according to Padgham. It was selected not only to accommodate the LH's sloping front profile, but also because at the time (early 1989) it was believed the industry as a whole was moving in this direction and, finally, bottom-feed injection would improve "hot" engine re-starts and eliminate stumble.

As with the 3.3-liter engine, the 3.5 was manufactured at Chrysler's Trenton, (Mich.) Engine Plant.

The fundamental change necessary to apply the 3.3-liter, overhead valve, V-6 engine to the LH platform was strategic -- turning it from the transverse "east-west" mounting of this same engine in certain other Chrysler passenger cars.

"The block was altered only in respect to the attaching points," said Padgham. "Another thing, we couldn't use the wrap-over intake manifold, so we came up with a unique manifold that gives us more torque."

In its LH application, the 3.3-liter engine will deliver a peak 1 53 horsepower at 5,300 rpm and 1 77 pound feet of torque at 2,800 rpm. It was recalibrated specifically for the LH.

"We also designed new exhaust manifolds," continued Padgham."but the base engine stays the same. The water outlet elbow is new and the accessory drive system is unique. It's a two-belt drive, one for the alternator and power steering pump and a second belt for the air conditioning."

In addition to these alterations, LH engine engineers also designed powerplant-bending struts between the block and transmission to provide more rigidity and stiffness. A three-point mounting system also was introduced.

The oil pan for the 3.3 is the only identical component with the 3.5-liter.

Francois Castaing said:

It was a challenge because when we started the LH program in January, 1989, the only engine we knew we had for sure was the 3.3-liter V-6. But we felt if the car was to be a success, it needed a brand new, high power, high technology engine.

The engine people on the team knew they had never designed a new engine that quickly (40 months). Also, the investment would be quite high. There also was the fear that when you commit a lot of money for the company, you want to commit it right and not make a mistake. Still, the team and engine people within the team realized the LH would not be a success unless the new engine was there at the same time we launched the car.

So instead of giving in to the negatives that it couldn't be done, that we couldn't get the technology, the slickness, the power, the low emissions, the fellows said, 'let's go for it.' They challenged themselves, they were convinced the 3.5 engine was an absolute cornerstone for the car.

General notes - 3.3, 3.5, 3.8 litre V6 engines

Ed Hennessy wrote: "[The 3.3] is a 100% Mopar design, introduced in 1990. It has a timing chain, not a belt. It's pretty reliable from all indications. Decent power and low end torque. All are 60 degree V6s."

The 3.5 (another 100% Mopar design) has a timing belt. The 250 hp version has an aluminum block. Douglas Miske wrote that the change interval for the timing belt is 84 months or 105,000 miles / 170,000 km.

3.3 93 mm bore 81 mm stroke OHV, roller lifters, short skirt
3.5 96 mm bore 81 mm stroke OHC, 24 valve, deep skirt, cross bolted mains
(many changes in second generation)
3.8 96 mm bore 86.9 mm stroke Bored and stroked 3.3


Jim Gathmann wrote: "when the 3.3 and 3.8 were tested for turbo applications, the engine blew its self to bits. The 3.3 and 3.8 were both used as prototype engines for the Dynasty police cruisers, and the idea was a police package Dynasty- with beefed up parts, a 3.8 and a turbo would be the Mopar replacement to the M-bodies (as they ended in 1989...). The problem was that the 3.3/3.8s would literally break apart on the bottom end during what Chrysler has called 'moderate boost.'"

Note: for those who believe the 3.5 is a Mitsubishi engine, Kevin Cobabe sent us the following chart:

Criterion Chrysler 3.5 (e.g. 300M) Mitsubishi 3.5 (e.g. Diamonte)
Power 250 hp @ 6400; 250 lb-ft @ 3900 205 hp @ 5000; 231 lb-ft @ 4000
Bore x Stroke 3.78 x 3.19 3.66 x 3.38
Compression 9.9:1 9.0:1

Bob Sheaves clarified the 3.5 engine's relationship

Bob wrote that the order of creation was:

Common problems

For the most part, this engine series is very reliable. See the introductory part for some issues.

Not starting

See the non-starting section. Note that the starter appears to be a weak point and may fail while making clicking noises instead of turning the engine over.

Rocker arms / rocker arm pedestal breakage

One problem - relatively common but still rare overall - with the 3.3 and 3.8 is rocker arm pedestal breakage. John "Auto Tech" wrote "I honestly don't know of any way to prevent it from happening but I do know of a repair that can be done 'on the car' and it works without replacing the head:

  1. Remove the rocker shaft and the broken tower .
  2. Drill out any threads in the tower.
  3. Drill out the head below the broken tower and install a Heli-Coil in the head . Now you can install a longer bolt through the rocker shaft and tower that will hold the entire assembly to the head.

The name-withheld engineer wrote: "if a mechanic reinstalls the rocker shaft on an engine that still has the lifters 'pumped up,' he must allow for them to be bled down or he risks breaking the shaft. Maybe in this instance the pedestal will fail."

Karl Williams wrote: "if they drill the hole deeper and tap for the original metric tap in the rocker tower, you can use the small head bolt for the fix. It is long enough and has the same thread as the original rocker shaft bolt. Chrysler recognized the problem and beefed up the rocker tower casting in the later model years. "

Jim Gathmann wrote in 2003: "I hear a lot about the rocker arm breakage problems on early 3.3s.... (even though such problems are rare and can be fixed forever by increasing the bore sizes on the top end oiling system...) guess what? CompCams makes a "ProMagnum Rocker Arm" which comes with a lifetime warrenty against breakage and is made of chromemoly steel.

"I suspect using these inplace of the OEM arms and forged pushrods, would result in a much more solid setup which would be more boost friendly, less likely to brake (in the case of the older 3.3s) and last a lot longer."

He also wrote:

The early years of the 3.3 did have problems with the rockers and the oiling system. I did not know when it was corrected. Apparently they fixed this by the 2nd year of production.

The rest of my 3.3 questions have been about finding ways to improve upon it so that it can handle more boost. Remeber, originally, when the 3.3 and 3.8 were tested for boost applications, the engine blew itself to bits. The 3.3 and 3.8 were both used as prototype engines for the Dynasty police cruisers, and the idea was a police package Dynasty- with beefed up parts, a 3.8 and a turbo would be the Mopar replacement to the M-bodies (as they ended in 1989). The problem was that the 3.3/3.8s would literally break apart on the bottom end during what Chrysler has called "moderate boost".

Rough idling

Kestas: If the rough idle is accompanied by a drop in engine speed when the air conditioner goes on, it may be that the engine is not getting enough air. Clean the throttle body, then check to make sure the idle air controller is clean and has full travel to the open position. (Take off the idle air controller, check for free movement, and give it a good visual inspection to make sure it is clean. It may need a shot of carb cleaner on the moving surfaces.

FCT: Check to make sure that the fuel rail recall was done (where applicable).

Mark: The engine is prone to intake manifold gasket problems that can cause a rough idle.

"Mopar Man and Woman:" "Remove and clean both throttle bodies. Synchronize throttle bodies. Remove IAC (ASI) [idle air speed/automatic idle speed] motor, but do not spray or soak with cleaner. Wipe tip off with cleaner on shop towel. Spray cleaner into bore in manifold. Make sure that hose that goes to air cleaner duct to intake right behind IAC is not blocked, collapsed etc. This is the source for air flow to the IAC on the 3.5L.

Perform minimum air flow test with DRB or other Scanner - should be 500-650rpm. If above, suspect vac leak, if low you have throttle body problems. At full operating temp, curb idle, what are desired IAC steps? Try cylinder balance test with scanner. If one or two cylinders are slightly different than rest, suspect intake manifold gasket failure. Also, after each repair, before starting, reset adaptive memory in PCM with scanner."

Cesar: "Just thought I share a similar problem I had with my 97 Eagle Vision w/3.5L that drove a lot technicians crazy, including field support folks, for 8 working days! The problem was one of the camshaft was slightly out of alignment in respect to its sprocket. This problem started after a water pump housing ("rear timing belt cover") was replaced and fuel rail recall performed. The symptoms I had after this effort was rough idle similar to the problem you've described. To verify valve timing on this engine there is a camshaft alignment special tool 6642 that must be utilized."

Exhaust flange noise

"Sounds like metal springs pulling apart every time I step on the gas pedal." Master mechanic John Mastriano wrote: "I've found that you can get rid of this noise permanently by running a round wire brush to clean off any rust build-up in the donut area of the exhaust manifold, then coat this entire area with never-seize (the silver stuff that gets all over everything) before installing the [new] donut."

Click here for other possible causes and solutions


(Contributor unknown) Finally got around to replacing spark plugs on my Caravan and knew it would be difficult. It took me 3 hours for that one plug alone all the rest were pretty accessible My main purpose is to caution any one attempting to do this.


While under there doing them I got some arcing and sparking (no apparent damage).

I have read some other posts on the tune ups and would not recommend doing your back plugs unless you have lots of patience and small arms (plus a box of band aids) .


There aren't many bolt-on performance upgrades for the 3.3/3.5/3.8 family. Mike Rodick did mention that one company is selling a nitrous system at about $800.

Hank Heykoop wrote about removing the air cleaner restrictor to gain more power (also suggesting upgrading the muffler): "The purpose for the restrictor is for noise control. It didn't increase much after removing it. To remove it you must first remove the air box then the restrictor can be unsnapped by pushing it out. This applies to the '91 through '95 vans [with 3.3 engines]. I'm not sure if the '96 and newer vans still have it. My fuel mileage and top end performance were slightly improved." ... "The restrictor that I'm talking about is a cylindrical piece snapped into the input end of the actual airbox. To remove it the airbox must first be removed from the car. Then it can be pushed out with your thumbs. Reinstall the airbox, filter and the duct. Leave the computer in place."

Patrick wrote: "I took the restrictor out and couldn't feel the difference, but my 0-60 improved from 11.43 to 10.67. I doubt that was all to do with the restrictor being out though."

Mike Rodick wrote: "I took my 91 Dynasty[3.3] with 140,000 miles to the local drag strip one weekend. I beat a V8 Ford Explorer twice, and almost had an early 80s Camaro V8 beat. ( Got me by .06 sec). The 3.3 holds her own!!" His best time was:

60 ft. - 2.4829 sec
330 ft. - 7.0943 sec
1/8 th mi. - 10.9268
1000 ft. - 14.2379 at 73.24 mph

Jim Gathman provided details on setting up a cold air intake for a slight performance boost:

I have a '92 Dynasty, so I have a little more engine-compartment room to work with.

On my car, the 3.3 uses a 52mm TB. Stock-wise, the engine had a black rubber tube going from the TB to the airbox (where the air filter is located). The crank-case, which in our cars requires a breather, has a small rubber tube which goes to the airbox as well.

Inside the airbox is the air filter, under that are two filters for the crankcase breather. Some of these engines (depending on year....) use a sensor which checks air temp. My car did not, however, I know that some of these models do- depending on year and model. Here's how to do it (or at least, how I did it).

Step 1: buy needed parts. I used the "Intiminator" (don't know who makes 'em) air filter, originally designed and marketed for our rice-burner friends (Acura if I remember right...). Pep-boys carries 'em for around $25. Cheaper then a K&N, and about as good. Next, buy the breather (about $10) made by the same company, also found at Pep Boys.

Step 2: Pop the hood and open up your airbox. Remove air filter, and breather filter(s). Next, on my car there were two metals clamps which held the large rubber tubing to the TB and the airbox. Remove these clamps (easy- just use a flathead screw driver to unscrew the screw on each clamp). Remove the large rubber tube.

Step 3: A small rubber tube/hose goes from the crankcase to the airbox. Remove it. Just pull on it until it comes off.

Step 4: A single bolt held my airbox to the car. Remove the bolt and the airbox lifts right out.

Step 5: Attach your new breather to where the small rubber tube/hose attached to your crank case.

Step 6: Depending on the space in your engine compartment, you may be able to put your air filter directly on the TB. Use a clamp like the ones used to hold on the large rubber tube to attach the filter. If space does not allow this, take your original large rubber tube and attach the air filter to one end of it- by using one of the left-over clamps used to attach the large tube.

Step 7: Since you removed your airbox, you could use your original large tube with an air filter on the end, and have your new air filter resting where the airbox was originally. Remember, cool air is better then hot air. The air where the airbox was located originally is typically cooler then the air directly around the TB. In my case, I rested my air filter right on where the original airbox was located.

Step 8: If your intake used a air temp sensor originally, take a dill and put a small hole in your new air filter, and place the air temp sensor right inside your air filter.

You're now done. Some people have tried other methods of getting cool air to their new air filters. Some 3.0 V6 Mopars have a tube going from just under the bumper up to the filter, basically the car moving around pushes air up the tube which is pointing at your air filter, thus giving you cooler, outdoor air. ... It took me less then 30 minutes to put in my cool air intake in my Dynasty- and that includes the time needed to go to Pep Boys and back!

Now for the ultimate mod, one could replace the 52 TB with a 58TB and bore out the intake manifold to match the 58 TB, and then set up a cool air intake. However the 58 TB is hard to find and may be as much as $300. A well worth mod though for a power boost. The 3.0 guys have done this for years.

Now mind you I did all this on a 3.3 '92 Dynasty- I don't know how similar or different that is from the newer 3.3s, or any of the 3.3s in vans- which are slightly different. So naturally some steps may be different slightly for your car.

Also note- on my car, I had to make the breather fit by really using force to get it on the crank case, then clamped it on tight. No problems with that. air filter fit perfectly on the air-box end of the large rubber tube- however one would have to bend the end of the tube so that it is round like the air filter, unlike the oval shaped inlet on the airbox. I also had to sand the edges around the end so that it fit snug in the air filter, which I clamped onto the tube.

Jim Gathmann also noted:

The way I heard it, when Chrysler made the 3.3/3.8, they did one of two things when they made it so only the A604 went with the 3.3/3.8. One possibility was the whole thing was a mistake, and the A604 should not have left the production lines until it was perfected. The other possibility was that they looked at the 3.3, and found its only weakness was with the crank and rods. So the stuck the weak A604 on every 3.3/3.8- thus ensuring the engine will never receive damage from mods, etc. Basically the A604 acts as a pressure valve and takes all the heat and damage- and not the engine's internals. The A604 will fail many times before the 3.3 will ever even get a hint of damage.

The result it the ability to add almost any reasonable amount of boost to the 3.3, and it will be fine (so long you don't go lean and use cool enough air). Once power gets too high however, the A604 will go- thus leaving the engine untouched (not bad.. cheaper to get an other A604 from a yard then to rebuild a 3.3/3.8.. and easier to swap trannies then engines!).

I've talked to the guy [who turbocharged his 3.3] [click here], and he's said the farthest he has gone with the boost is 15psi... now if I remember he claims to be running stock fuel system and only something like 4 or 5 psi at the moment. The 3.0 guys claim his setup is a fake and will not work.. and not knowing anything about turbos, I say the pics are as is- I won't say as to rather or not they work one way or not.

Timing and such (Jim Gathmann)

The coil pack has 3 coils. Each coil is for 2 cylinders, and the PCM (computer) sends one timing signal to each coil (so basically there are 3 timing signals- one for each coil).

The reason for this is that the PCM gains better control over the cylinders. This way, for some reason, the PCM could have a different signal for each grouping of cylinders. But since these early PCM's lacked knock detector curcuits, I fail to see what you'd want control over each pair of cylinders.

At any rate, one could retard the timing by placing a timing controller unit on each of the 3 lines between the coil and PCM.

Now the cost of 3 timing controlers, @$150+ a piece, comes to about the same price as a complete DIS MSD ignition system!

But- if you don't want to get into that kind of money, here's an idea- build your own timing controller. I found this site: which deals with making your own microcontroller timing controller using the same microprocessor as the megasquirt.