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Viggen pistons?

5.6K views 35 replies 11 participants last post by  Aerolike9  
#1 ·
How bad are the 99 viggen pistons? and where can I get new ones?
 
#3 ·
Send an old piston to J&E and they will make a custom new forged one of the same dimensions, or even slightly lower compression if you want. (Lower compression height compromises strength, which is the reason the pistons were "bad" in the first place.

Secondly, the '99 pistons are the worst of the T7 pistons. The later ones got trapezoidal small rod ends, which allowed for beefier piston reinforcement. The compromise is that the my 2000+ con rods won't be as good for high revving.

All of the T7 pistons, rods, and crankshafts are lighter than the previous 2.3L engines. But a forged set of pistons shouldn't make anything much heavier, and if made out of the 4340 low expansion alloy, they shouldn't harmreliability any.

You could also sent a set to Mahle, but I'm not 100% sure if they do custom pistons or not. I know J&E does as I have a set in my friends 1990 Dodge Shadow.

Adrian~
 
#4 ·
So as far as the J&E they would forge me a new set and it would be stonger only if i told them to lower the compression height?

Also assuming i like high reving the J&E would be the best option?
 
#5 ·
No no. Ok let me explain ...

Taller piston = stronger piston (usually)

Higher Compression = Taller piston = stronger piston = more likely to knock = compromise

Lower compression = shorter piston = weaker piston = less likely to knock = yet another compromise

You just have to decide which compromise you like best. 9000 Aero's are getting 500+ hp on 9.3:1 compression if your gas is good enough.

MAHLE would actually be the best for high revving. They use a lightweight, but strong, box-in-box design. I do not know if they make custom forgings though. Let alone at the relatively cheap prices J&E make them for.

Makes sense?

Adrian~
 
#6 ·
that makes sense the question is what is the bonus of each... you stated the negative sides.... but whats good about each one as far as performance? also what is the stock compression?

Yeah... price is not the issue its me wanting alot of HP out of a car not made to produce that much... aka im willing to pay the price.
 
#7 ·
Also if the compression changed wouldnt i need to program the ECU for that?
 
#8 ·
If you have the money, see if MAHLE will make their box-in-box design for your engine. Your stock con-rods are both strong, and lightweight; combined with a lightweight forged and strong piston, it should make for a very nice engine.

If you have only roughly $1,000 look into J&E pistons. They make custom pistons for about $400-800 a set. Get them at around 8.4-8.8:1 if you plan to make big power on pump gas. Yes you CAN go higher than that, and still make lots of power, but it's easier with lower compression. If possible send the pistons to www.performancecoatings.com and get them tri-coated. (Ceramic on top, moly on sides, and dispersant on bottom.) That will make them even tougher to detonation.

Adrian~
 
#9 ·
The ECU should be able to handle the lower compression just fine. It won't significantly change airflow. You'll just notice a drop in fuel mileage when cruising, and probably some additional ignition advance during warm weather when the stock pistons were too high compression for that heat + pump octane combination.


Adrian~
 
#10 ·
Right on... well seing as thats quite expensive it will prob come at a later time... but what HP/FTlBS can the stock ones handel?
 
#11 ·
but what HP/FTlBS can the stock ones handel?
It's more a question of how much KNOCK they can handle. Unfortunately the answer is almost none.

Anything you do which increases cyllinder heat will make the pistons weaker. (Aluminum gets weaker with higher temps.)

For safety I'd switch to the 82C degree thermostat from the 9000 Aero. That significantly reduced the tendancy of the ECU to reduce power from knock. Also I'd make some ducting to your intercooler (if you get a larger one, make sure that all of the air goes over it, and not just SOME, proper ducting), insulated all your intake piping, and do everything you can to reduce heat in the engine. Heat = knock = blown motor.

Then upgrade slowly by spending money on supporting modiications that reduce heat while saving for pistons. Once you have money for pistons and an upgraded ECU, then you'll be ready to make some SERIOUS power.

Also, the 06-cm exhaust housing from the 9000 Aero turbo will reduce heat in the combustion chamber by reducing backpressure. So too will headers. Headers have been shown time and time again to SIGNIFICANTLY reduce EGT, and thus cyllinder temps. CoolAr is bettAr.

Adrian~
 
#12 ·
Ok, well my stage 3 ECU should be in soon... so im thinking i need to reduce engine heat... I took out that shit insulation on the hood and the car actually seems ALOT colder... I also cleaned the air filter and took off my front licence plate and i notice my turbo does stay alot colder. But yeah.... once i have more money I guess pistons would be a good idea...
 
#13 ·
Thermostat - Thermostat - Thermostat!!!

Part number: 88 17 538

They're normally for the 9000 Aero, but they fit just fine in the 9-3 Viggen, and any other Saab ... in fact, every 16V Iron Block Saab has compatible thermostats.

www.thesaabsite.com sells them for $18 http://www.thesaabsite.com/9000/9000cooling.htm

Trust me, more difference in detonation resistance than any other mod I've tried. ;) If you can, have the dealer re-program the cooling fans to come on at 200F degrees instead of 212 as well.

Sorry I didn't emphasize that before, I was giving a total list. If you're going to do ONE thing, that is the one thing to do. That, and the duct tape over the gap between the top of the intercooler and the bumper. Costs like $2, and makes more difference than even I thought it would on hot days.

Get it? Got it? Good!! Keep on Saabin'!
 
#14 ·
who makes good headers for a 99 saab viggen?
 
#15 ·
im just scared im gona over heat once i crank things up.... anyone else have anything else that could help?
 
#16 ·
Taliafferro do. But they are $800 ... the 82C thermostat is $18 ...

Headers could still be better. I don't think the Taliafferro Saab setup is ideal ... but they are good. Make sure to combine them with the 06-cm exhaust housing. That's the REAL bottleneck. Even the guys working at the Saab factory in TrollHattan reccomend that for power above 270 hp.

The slight loss in spool up from the 06 cm housing should be compensated by the headers!

And don't forget the thermostat or so help me god I'll come over there and HURT you! lol kidding ... but seriously ... 82C is 180F degrees ... and the stock 89C is 193F degrees. It's a noticable difference! Cooler coolant = cooler cyllinder walls = cooler pistons = stronger pistons!!!

Adrian~
 
#17 ·
where would i aquire the 06-cm exhuast housing?
 
#18 ·
also how would i go about installing that theromstat?
 
#19 ·
06-cm exhaust housing can be gotten of any used 9000 Aero turbo from 1994-1998. Even if the turbo is in bad shape, the housing should clean up nicely. Remember, you just need the exhaust housing ... and you'll need to use a grinder to port the stock manifold a little.

Check out this forum. ERP did it recently, and posted exactly how!

A turbo in bad shape, should be very cheap. Check e-bay?

The thermostat just requires the removal of 4 bolts, the $18 kit comes with a new rubber seal. I used Mopar RTV solicone (way the fok better than the crappy stuff at Autozone or wherever) just in case ... but the factory uses no sealant. So just clean up the surface of each.

If you can get any of their black RTV silicone from a dodge dealer go ahead. My best friend is a technician and this stuff doesn't even COMPARE to the stuff you buy anywhere else. It's so strong that it seals instantly, and it smells so strong that if you're not careful you'll get dizzy just leaving the cap off the tube sitting near you. ;)

Adrian~
 
#20 ·
wana link me to that forum :)

Thanks for helping me our saab tuner.
 
#22 ·
Boxerchip said:
also how would i go about installing that theromstat?
forgive me Boxer...lol...I can't help but laugh a little. I noticed your post about pistons...then the exhaust housing, and then you ask how to change the thermostat....I just lost it, and had to apologize. I just wondered if you noticed the irony of your question, or was that on purpose.

all in fun...

regards
 
#23 ·
Over the last few days, I tore off my hood fabric, wrapped my pipes..and added what I call "Greddy Intercooler Tape" over my intercooler.

Awesome ideas guys, keep 'em coming. I will order the thermostat as well. And for any nay-sayers, One of the number one mods for a Grand National is 160degree T-stat. I guess we will settle with the 180 one. 8) I have wondered about a diff t-stat, and Adrian came through.
 
#24 ·
You should note though, that with the cooler thermostat the engine may still run as hot as it did before if there isn't much airflow over the radiator. On the highway is where the biggest benefits will be. Since our cars are FWD, that's where our power is really needed anyway. 8)

When the A/C is of, on T5 and T7 the cooling fan kicks on at 212F regardless of t-stat. I wanna see if I can get the dealer to change mine to 200F via Tech 2 ... just another thing on the to-do list.

Also, if Dr Boost says there is something wrong with the Viggen intercooler, then there probably is. What I meant by my previous statements is not to judge and intercooler just by it's size, and the fact that it is a factory unit. There is probably some internal flaw to it, because its size, shape, and flow rate is OK even for a lightly modded engine ...

.... I guess for whatever reason it just doesn't cool as well as it should.

Either way ... ducting ducting ducting! Even with the Viggen intercooler, ducting the air so that it has to go through the intercooler has made a significant difference for me, especially when I hold boost for long periods at high speed.

:D Keeep the ideas coming!!

Adrian~

Edit: This week or next an Aero-space engineering friend of mine (he makes specialty aerospace and automotive equipment) is going to teach me to TIG weld. So after I get some practice, there may be a very nice new intercooler in the front of my Viggen,. I'll let you guys know if it's sucessful. A core that is equal to, or better than, anything I've seen on the market can be bought for around $400 from Bell Intercoolers .... just a matter of TIG welding the ends properly. We'll see how it works out.
 
#25 ·
i would just like to say there is nothing wrong with the vigeen intercooler's cooling, it is very efficient i mean touch the opposite end tanks whenever u get a chance after a long ride, u will see what i mean, the problem with it is that it doesnt flow enough