intercooling 1981 8V turbo non-APC car

[saab_o_naut]

[ Copied from this thread at CCSW ... ]

Ok I've started some initial trial fitting work to see what will need to move, etc. and so far I've found that the horn on the left side and the fuel vapour line (a piece of hard nylon line) from the charcoal cannister both get in the way of where the intercooler will sit.

I'm in the process of sorting out a different want to mount the horn, but the fuel vapour line is a worry since there isn't really another place to route it and the only option might be to completely replace the line with so I can bend it differently and not interfere with the location of the intercooler.

The engine oil cooler lines do definitely get in the way too - I found a copy of Mark Jeter's 8V turbo intercooler guide and he mentions that the oil cooler lines need to be extended to 47" and 48" respectively (basically to make them 4' or approximately 120 cm long) so the oil cooler can be shifted to the right side of the radiator support member.

Other than that, and the fact I'm missing the pipe that should go from the outlet side of the air filter box the turbo's air inlet port, and the mounting hardware for the intercooler, I'm ready to get it all installed!

Apparently the filter box to turbo air pipe (metal pipe instead of plastic) from a 99 turbo fits perfectly for replacing the plastic and rather convoluted air pipe used with the 8V turbo c900's.

I also don't have a replacement for the lower radiator hose. In my car's case, it has an auto transmission so I suspect the only hoses that suit (mentioned in Mark's guide) are designed for cars with manual tranmissions. Will need to research this aspect some more and see if there is a real Saab hose that will do the job, or I'll need to fab something using plain hose, etc.

Who can recommend some ideas regarding the hose issue? I am going to buy a new radiator for the car so if I can figure out what to do with the bottom hose running from the radiator to the water pump via the in-line ATF cooler, I can take care of that at the same time as sorting out the radiator problem.

Craig.

[Crazyswede]

You could try something new and put either a different intercooler in or mount it in a different location. We have discussed on and off mounting the intercooler above the engine like on the Subaru's. This would allow for fewer bends and less restrictions on the intake side. Also might help on your line rerouting.

[saab_o_naut]

You could try something new and put either a different intercooler in or mount it in a different location. We have discussed on and off mounting the intercooler above the engine like on the Subaru's. This would allow for fewer bends and less restrictions on the intake side. Also might help on your line rerouting.

I have just removed the A/C system from the car so I could go along the route of a FMIC but I wanted to try the T16 intercooler route to start with. I'm doing the same thing with my 89 16V c900 too and trial-fitted the intercooler parts today. That particular car is gaining a turbo as well but that's a bit further back from being done. The 81 turbo car is the focus at the moment.

Above the engine is an interesting idea. I've seen a lot of skinny intercoolers that could, with re-location of the ignition coil, etc. fit above the radiator and still clear the hood, though airflow might not be the best. One thing I want to avoid is hacking away at the structural parts of the car and that might be needed to go with a FMIC. An above-rad mounted intercooler may work without any structural changes. and the T16 intercooler definitely will once the niggly bits are resolved.

The engine runs superbly well though the wastegate on the turbo is set a little too high resulting in knocking under heavy load as the boost gets to around 8 to 9 psi, so the intercooler addition is intended to temper that and lift the boost 'ceiling' (it's a non-APC engine). I'm also going to install a Knocksense unit so I have a visual indicator when knock is close to occuring (it's not always possible to hear it!).

Craig.

[Crazyswede]

the visual knock sensor won't really do much for you. By the time it shows you that the engine is knocking the damage will have already been done. your engine should not be knocking at only 8 or 9 psi. Airsweden aka snakes Malone ran a 16v na engine with a turbo setup and high boost. that engine lasted quite a long time before it went poof. You may have a carbon build up or you may not be getting the proper fuel or your timing may not be set correctly. Installing the inter cooler will help you a little bit but its not going to solve all of your problems. You may want to consider yanking out the CIS system and putting a megasquirt or similar Fuel injection system in. This alone should help out quite a bit more.

[Jordan]

I'm pretty sure you can do without a charcoal canister and why not fit an APC? It's a completely separate system that is simple and effective. Just find one that '86+.

[Geoff]

SAAB built T16 c900s with automatic transmissions and intercoolers. All 16v turbo cars in the US got intercoolers, regardless of transmission, etc. So you could get a lower radiator hose from one of those cars. While you're re-rounting things, add a T16 air cooled transmission cooler as a secondary cooler for that crappy tranny. I've had good luck running Amsoil synthetic racing Type F transmission fluid in those boxes.

I have some SAAB literature (accessories catalog?) that shows an intercooler kit for 8v C900s. Its the intercooler, hoses, and some other misc stuff. I don't remember what though...

CrazySwede is right, I don't think you should be getting too much knock with 8-9 psi. Isn't stock boost 7-8 psi? Those engines are low compression. Maybe your injectors are dirty or need a tune up or your timing is off? I agree with Jordan, install an APC. I installed one on CrazySwede's old car. It was super easy, I think I did it in a half hour. Although... with an earlier block you may need to drill and tap a hole for the knock sensor bolt.

[SaabsBreakDown]

the visual knock sensor won't really do much for you. By the time it shows you that the engine is knocking the damage will have already been done. your engine should not be knocking at only 8 or 9 psi. Airsweden aka snakes Malone ran a 16v na engine with a turbo setup and high boost. that engine lasted quite a long time before it went poof. You may have a carbon build up or you may not be getting the proper fuel or your timing may not be set correctly. Installing the inter cooler will help you a little bit but its not going to solve all of your problems. You may want to consider yanking out the CIS system and putting a megasquirt or similar Fuel injection system in. This alone should help out quite a bit more.

detonation takes a long time to negatively affect an engine, especially in the situation we are talking about. you could drive on that engine for a month with detonation under boost before you saw any damage. visual knock sensors are not to be discouraged.

[TRAILINGTHROTTLE]

TRAILINGTHROTTLE has been rendered: Speechless

[SaabsBreakDown]

http://www.streetrodstuff.com/Articles/ ... Page_2.php

Detonation

Unburned end gas, under increasing pressure and heat (from the normal progressive burning process and hot combustion chamber metals) spontaneously combusts, ignited solely by the intense heat and pressure. The remaining fuel in the end gas simply lacks sufficient octane rating to withstand this combination of heat and pressure.

Detonation causes a very high, very sharp pressure spike in the combustion chamber but it is of a very short duration. If you look at a pressure trace of the combustion chamber process, you would see the normal burn as a normal pressure rise, then all of a sudden you would see a very sharp spike when the detonation occurred. That spike always occurs after the spark plug fires. The sharp spike in pressure creates a force in the combustion chamber. It causes the structure of the engine to ring, or resonate, much as if it were hit by a hammer. Resonance, which is characteristic of combustion detonation, occurs at about 6400 Hertz. So the pinging you hear is actually the structure of the engine reacting to the pressure spikes. This noise of detonation is commonly called spark knock. This noise changes only slightly between iron and aluminum. This noise or vibration is what a knock sensor picks up. The knock sensors are tuned to 6400 hertz and they will pick up that spark knock. Incidentally, the knocking or pinging sound is not the result of "two flame fronts meeting" as is often stated. Although this clash does generate a spike the noise you sense comes from the vibration of the engine structure reacting to the pressure spike.

One thing to understand is that detonation is not necessarily destructive. Many engines run under light levels of detonation, even moderate levels. Some engines can sustain very long periods of heavy detonation without incurring any damage. If you've driven a car that has a lot of spark advance on the freeway, you'll hear it pinging. It can run that way for thousands and thousands of miles. Detonation is not necessarily destructive. It's not an optimum situation but it is not a guaranteed instant failure. The higher the specific output (HP/in3) of the engine, the greater the sensitivity to detonation. An engine that is making 0.5 HP/in3 or less can sustain moderate levels of detonation without any damage; but an engine that is making 1.5 HP/in3, if it detonates, it will probably be damaged fairly quickly, here I mean within minutes.

Detonation causes three types of failure:

1. Mechanical damage (broken ring lands)
2. Abrasion (pitting of the piston crown)
3. Overheating (scuffed piston skirts due to excess heat input or high coolant temperatures)

The high impact nature of the spike can cause fractures; it can break the spark plug electrodes, the porcelain around the plug, cause a clean fracture of the ring land and can actually cause fracture of valves-intake or exhaust. The piston ring land, either top or second depending on the piston design, is susceptible to fracture type failures. If I were to look at a piston with a second broken ring land, my immediate suspicion would be detonation.

Another thing detonation can cause is a sandblasted appearance to the top of the piston. The piston near the perimeter will typically have that kind of look if detonation occurs. It is a swiss-cheesy look on a microscopic basis. The detonation, the mechanical pounding, actually mechanically erodes or fatigues material out of the piston. You can typically expect to see that sanded look in the part of the chamber most distant from the spark plug, because if you think about it, you would ignite the flame front at the plug, it would travel across the chamber before it got to the farthest reaches of the chamber where the end gas spontaneously combusted. That's where you will see the effects of the detonation; you might see it at the hottest part of the chamber in some engines, possibly by the exhaust valves. In that case the end gas was heated to detonation by the residual heat in the valve.

Now notice the specific output of the engine affects its sensitivity to detonation, and a saab turbo is definitely in the higher end of that. probably 1.2 hp/ci. in my experience though I have had driven home on summer days with engines that detonate on hills and have never had a problem with anything.

In no event should a visual knock sensor be discouraged because "By the time it shows you that the engine is knocking the damage will have already been done."

[Crazyswede]

Detonation/knock is simply what occurs when the conditions in the the cylinder are such that the fuel just explodes instead of a nice controlled power inducing burn. There is also pre-ignition which can also result in "pinging" which is usually caused by carbon buildups in the cylinder. Pre-ignition causes the flame front to begin before the spark ignites the fuel air mixture. This typically causes the piston to fight the growing force of the expanding fuel/air mixture. Pinging doesnt usualy result in engine failure but it certainly doesn't help engine performance.

[Jordan]

TRAILINGTHROTTLE has been rendered: Speechless

Yeah common Matt, look at all those mercedes diesels that just knock all the time and last for hundreds of thousands of miles!

[SaabsBreakDown]

pre ignition is not what happens in a turbo saab.

Every time your APC needle moves up and down that's the APC system taking the boost up until it knocks and then bringing it back down. EZK and most modern ignition systems operate in the same way, effectively. Knocking is not damaging to an engine unless it goes uncontrolled, and the whole point of his visual knock sensor is so he can detect and adjust the engine to stop detonating (knocking).

From the same article I linked to (which you apparently didn't read):

A glowing spot somewhere in the chamber is the most likely point for pre-ignition to occur. It is very conceivable that if you have something glowing, like a spark plug tip or a carbon ember, it could ignite the charge while the piston is very early in the compression stoke. The result is understandable; for the entire compression stroke, or a great portion of it, the engine is trying to compress a hot mass of expanded gas. That obviously puts tremendous load on the engine and adds tremendous heat into its parts. Substantial damage occurs very quickly. You can't hear it because there is no rapid pressure rise. This all occurs well before the spark plug fires.

[TRAILINGTHROTTLE]

if i ever have to cite "streetrodstuff.com" to make a point...consider said point "null and void".

SaabsBreakDown: seriously---you are surrounded (on this forum) by saab people, and saab people that are trying to help other saab people, like myself, to go faster. what they are dishing out is based on experience, and a hell of a lot of it. in a couple of months my rallycar will be finished, and will run. and it will be a much better car than it would have been without this crew, and their hospitality, support and advice. learn from what they have to say, and from the cylinder heads and pistons that they have destroyed. we know that you like saabs, everyone here does, thats why were here. its not a competition, its a community and a tool. help out where you can-and im sure that you can--but dont patronize me/us about detonation and the like...its insulting. i didnt worry as much about it, either...then i had to start paying for my own parts. you should see what happens inside an aircooled porsche engine when a little spark knock breaks a chunk off of a spark plug insulator.(not 'effin harmful 'etall) learn from these folks, they know what they are talking about.

[Crazyswede]

pre ignition is not what happens in a turbo saab.

Every time your APC needle moves up and down that's the APC system taking the boost up until it knocks and then bringing it back down. EZK and most modern ignition systems operate in the same way, effectively. Knocking is not damaging to an engine unless it goes uncontrolled, and the whole point of his visual knock sensor is so he can detect and adjust the engine to stop detonating (knocking).

From the same article I linked to (which you apparently didn't read):

A glowing spot somewhere in the chamber is the most likely point for pre-ignition to occur. It is very conceivable that if you have something glowing, like a spark plug tip or a carbon ember, it could ignite the charge while the piston is very early in the compression stoke. The result is understandable; for the entire compression stroke, or a great portion of it, the engine is trying to compress a hot mass of expanded gas. That obviously puts tremendous load on the engine and adds tremendous heat into its parts. Substantial damage occurs very quickly. You can't hear it because there is no rapid pressure rise. This all occurs well before the spark plug fires.

Sorry I guess I haven't been inside the cylinder lately to experience what is truly going on. Perhaps if you were to read my post you might be able to see that I was trying to explain the different modes of improper flame development in any engine...turbo or non turbo. believe me I am fully aware of how the apc and ezk systems work. I even put a car together that used both apc and ezk once.

Now, for the detonation deal. Detonation can occur in any engine if the conditions are correct. You are correct in saying that an engine may live for many months with a mild detonation problem. However, an engine may only last for several seconds if the detonation is bad enough. If you are only running around 9 or 10 psi in an 8v and you are experiencing significant amounts of detonation (knock) then something else is likely wrong...ie your timing is off, you have crappy plugs, your spark plug wires suck, your cap and rotor are toast, your coil is crap, your engine is too lean, etc etc. I have seen pistons with holes punched through the top after one event or one high speed run at full or excessive boost.

The best way to reduce knock is to make sure your engine is up to spec in the healthy tune department....plugs, cap, rotor, wires, coil, timing, air filter, fuel filter, proper grade gas, properly functioning fuel system, healthy grounds, good battery. Once this is taken care of then consider running colder plugs like the NGKBCP7EV's if they are still available (16v...cant remember what the 8v's run). Pick up the Bosch red coil, run the 8.5mm magnecor wires, switch to a K&N air filter...8 or 16v. If the engine is high mileage and has never been apart consider pulling the head and having a 3 angle valve job along with a good cleaning done. Replace the gaskets and seals. Install the intercooler, then if more boost and power is needed look to water injection, misting water jets, alternate fuel systems, etc etc.

And saab engines most certainely can ping...turbo or not.

Now the cool thing is that many of the mitsubishi engines are good for 300 hp on regular pump gas without any detonation issues.

And then theirs my KTM...11.5:1 compression, 90 hp...I can run 87 octane fuel with carbs and no detonation issues. I tend to stick to the higher octane to be safe....but still pretty cool. Of course the bike only weighs 500 lbs. Big difference on the load curve.

[Hans]

Every time your APC needle moves up and down that's the APC system taking the boost up until it knocks and then bringing it back down.

Maximum boost allowed by the APC is not knock-limited, as you imply; there is a maximum level beyond which the APC will not go higher, even if there is no knock. If you are running low octane fuel, driving in hot weather, or with a poorly-tuned engine, it can appear that the APC is limiting knock via sensor feedback because the engine always knocks as it approaches max boost, and you can watch the needle twitch.

EZK and most modern ignition systems operate in the same way, effectively.

EZK sort-of knock-limited. It will periodically (upon each start-up??) advance the timing until it detects knock, then set a maximum advance that's a couple degrees less advanced. EZK does not allow the engine to continually run at the knock limit.

Knocking is not damaging to an engine unless it goes uncontrolled, and the whole point of his visual knock sensor is so he can detect and adjust the engine to stop detonating (knocking).

I agree that, lacking some sort of boost controller, a visual cue that the engine's unhappy would be helpful. But to assume that a turbocharged engine will tolerate a bunch of knock for long periods of time is tempting fate and, depending on the engine, not necessarily true.