9-5 vs 9000 pistons.

[frostgrey]

This is couple pics between B235(9-5) and B234(9000) pistons.
Is anything difference ??










Clean ones is new B234 pistons(2.3T 90-92) and those is coming in my 9-5 2.3t in summer. Then i can take "little"bit more power out my engine. About 300hp is target. Connecting rod is coming too from 2.3i 9000 -91( same than turbo).

[95power]

I do not believe myself that there is so much difference between T5 vs. T7 pistons - what comes to power tolerance.

If one wants to build B235 better, why not use proper parts in the first place? With proper parts I mean good quality forged pistons, like JE:s, Wisecos etc., which are designed for high powered applications. These quality items are not so much more expensive than new T5 pistons.

Here are the pistons for my new B235 engine:



Connection rods for this same engine:

[ylee coyote]

like for like there is a huge difference between the OEM pistons

shure you can use forged 235 pistons and they will be better but you will still get blow by and still be running the risk of the black death killing your engine

234 pistons work...

I am replacing my siezed 235 block with a 234 block
Easy to get hold of ,cheap,reliable ,and will take 500 hp no problem...

[Chris 9-5]

Ylee is the key to your post the word "block" sorry to sound thick here.

There is a massive price difference between getting 9000 pistons, and even a block than buying the really shiney forged stuff. Changing the block would be a much more economical job surely? And if that gets us beyone that "300 bhp" piston melt down figure is a winner isnt it?

[95power]

Originally Posted by ylee coyote

like for like there is a huge difference between the OEM pistons

shure you can use forged 235 pistons and they will be better but you will still get blow by and still be running the risk of the black death killing your engine

234 pistons work...

I am replacing my siezed 235 block with a 234 block
Easy to get hold of ,cheap,reliable ,and will take 500 hp no problem...

B234 or B235 engines in standard form are not something to recommend for 500hp use. At least if you are going to use that power. It's just urban legend that B2x4 engines can cope with 500 hp ( std internals ) for longer than a couple of thousand kilometres.

There is no reliable source who has explained reasons for T7 piston failures. Or maybe I've missed something? T7 engine has different design philosophy compared to T5 engine ( lighter internals, lower friction, better materials for example in nimonic exhaust valves etc. ) as a whole. For example piston rings locations are different ( T5 vs. T7 ) because of the emission regulations. One has to remember as well that T5 pistons are heavier than T7 pistons.

What comes to blocks, I'm very interested to know why B234 block is better than B235 block? If you've information or own experiences on this subject, please let us know.

[Chris 9-5]

95power what would you say is the maximum power level for the standard pistons in the 2.0 engine? We have seen suggested 300 bhp but I think Maptun Stage 6 is 315

I'm not really thinking for sustained hard driving, just the maximum level for occaisional use

Numbers 95power - erm ok, a used 9000 block say £300 a set of forged pistons £600 plus the rods at about £800 plus fitting to the block...............

[frostgrey]

I paid those 120€ 4/st and i dont think that i get any forged pistons that price, even closely.

I will take engine off , because cam chaing is noise and clutch slipping. Same i change those pistons, rods and all bearings. Intercooler and DB will change too. I make this for use, not racing(maybe little bit .

I think that, whit those mods engine can handle about 300hp with no problem. Cars is every day use and my girlfriend drive that maybe more than me, so i hope that 300hp be enough power for she

I drive with my -79 Saab 96´s

[95power]

http://s91196822.onlinehome.us/finaly.wmv

[Raven18940]

Looking at those pictures, it looks like the 234 pistons are a bit taller measureing from where the rod connects and not as flat as the 235 ones. Are you sure these are actually gonna fit? I understand the desire to cut back on blow by gasses that killed your first engine, but what about the oil pump? That's what really needs changing, back to the old 9000 design that was a lot more reliable, or at least a brand new 9-5 pump.

[Vigge]

if 300hp would be the limit for std B235R pistons my current set-up should have blow up long time ago... Generally speking what will work for one will not work for the other. For instance one Hirsch employee wrote on the swedish saab board that they ran a B235R engine up to 400hp with out failure, but at the same time there are people who have had failures with std. power levels. What does this tell us?
There are other variables with in the B235R construction besides the physical piston it self that will lead to the "known" failure.
I have yet seen the following information
-is the B235R more vulnerable to piston failure with 350hp than 250hp? We know the both can fail. Out of all the tuned B235 piston failures how many would have broken anyways? WE DO NOT KNOW

Anyhow I will swap mine out before I find out weather they last or not. It is ALOT cheeper to do the preventative maintenance than to end up in the situation shown in that video above.

[Chris 9-5]

I agree with you Vigge, as you say how many failed due to the higher power rather than a manufacture problem in the first place - its not known.

I guess its just "that" step, the engine re-build step with forge pistons and rods is a real leap forward from what has been up to now, "bolt on and software" improvements, I just wondered where the line was where it became essential.

Thanks Chris

[ylee coyote]

Originally Posted by 95power

B234 or B235 engines in standard form are not something to recommend for 500hp use. At least if you are going to use that power. It's just urban legend that B2x4 engines can cope with 500 hp ( std internals ) for longer than a couple of thousand kilometres.

There is no reliable source who has explained reasons for T7 piston failures. Or maybe I've missed something? T7 engine has different design philosophy compared to T5 engine ( lighter internals, lower friction, better materials for example in nimonic exhaust valves etc. ) as a whole. For example piston rings locations are different ( T5 vs. T7 ) because of the emission regulations. One has to remember as well that T5 pistons are heavier than T7 pistons.

What comes to blocks, I'm very interested to know why B234 block is better than B235 block? If you've information or own experiences on this subject, please let us know.

Urban legend ...
I do not think so
55,000 miles and going strong on standard internals at 400 + bhp
with another 190,000 on the engine in total...

The 234 block=235 block
Its the pistons/conrods/crank? are different
the t7 head is better ..so keep that

change the bottom end ,get the best of both worlds...

You can buy a recon 234 block with rings and bearings for £600....

[Chris 9-5]

Originally Posted by ylee coyote

You can buy a recon 234 block with rings and bearings for £600....

Thats probably less than the Forge pistons alone

[95power]

Originally Posted by Raven18940

Looking at those pictures, it looks like the 234 pistons are a bit taller measureing from where the rod connects and not as flat as the 235 ones. Are you sure these are actually gonna fit?

You've to change both pistons and connecting rods.

[frostgrey]

Only "problem" with those pistons is that compression ratio fall of little bit.

from 9.3 to 8.5. Because pistons are from 90-92 B234 and hollow of top are little deeper than T5 engines.

Knows anybody is that big problem with T7?

Are that big effect for discharge or anything else?

[boxman]

those 234 pistons will not fit your 9-5 engine, they are too long you need the 9000 pistons from 94 - 98 not 90 - 93 also when using the 9000 pistons you also need to use the 9000 head gasket too to keep the comp' ratio correct

[Chris 9-5]

Originally Posted by boxman

those 234 pistons will not fit your 9-5 engine, they are too long you need the 9000 pistons from 94 - 98 not 90 - 93 also when using the 9000 pistons you also need to use the 9000 head gasket too to keep the comp' ratio correct

Boxman do you agree that these components are stronger, due to Saab lightening the 9-5 stuff for improved "efficiency"? If so then I sense a number of new projects topping the 350-400 bhp mark

[frostgrey]

Pistons high is same between 90-92 and T5(this is measured), Only the hollow on top is differen. And B234(longblock) comp.ratio is 8.5. After 94-(t5) the comp.ratio raise for 9.3.
Luckily my brothet is one damaged B234R block where i can some day fit those pistons and rods before i take my own engine out

[XAAMOTTOMAAX]

Originally Posted by 95power

There is no reliable source who has explained reasons for T7 piston failures. Or maybe I've missed something? T7 engine has different design philosophy compared to T5 engine ( lighter internals, lower friction, better materials for example in nimonic exhaust valves etc. ) as a whole.

To answer this you need to look at the differences of the two pistons (T5 and T7). The problem is that most people stop with the obvious differences, size, shape, etc.

The most important difference is the one that gets the least amount of discussion. That difference is the the difference in conditions faced by the two pistons. I'll go over some examples...

What are some of the most common problems faced by T7 cars?

1. Weak and failing oil pumps that can drop to dangerous pressure levels before any warning light ever appears. This has been shown to be independant of sludge and clean engines have failed from oil starvation despite not having a sludge issue.

The pistons are cooled by oil squirters. If the oil pressure is much much lower than it is logical to assume the pistons are not having as much oil squirted on them and this reduces the cooling they would normally benefit from.

2. Faulty PCV systems are also a very common issue.

The PCV system failures have shown to cause an increase in blow by as well as over pressurization of the crankcase. This can lead to sludging which can also lead to oil starvation, low oil pressure and see point above. Another issue this creates is that oil (not just fumes) is sucked into the intake stream to be combusted. How many people have seen intercoolers caked with oil? Oil in your air/fuel mixture will rob the fuel of it's octane and we all know how important octane is.

3. Mass air flow sensors commonly fail or at least show to have inaccurate or inconsistant readings.

The differences between T5 and T7 are many but the most important is the method of fueling calculation. I won't get into the specifics but with the readings of the MAF sensor being so critical to T7 fueling, it could be that this simple part plays a large roll in knock if the part is not functioning correctly.

4. Direct Ignition Cassettes or IDM could be the most common and well known problem with T7 cars.

Can the ECU accurately sense knock if the IDM is failing? Many have said there were issues that were suddenly fixed when the IDM was replaced. The old view that these parts simply worked or did not work is no longer accepted. Just because your car starts and runs does not mean the IDM is working at 100%. If the ECU can not "hear" the knocking, how does it know to cut back on power?

I'm sure there are other factors. I think it's more the systems in place than just the size of the pistons that is causing these failures.

[95power]

Originally Posted by ylee coyote

Urban legend ...
I do not think so
55,000 miles and going strong on standard internals at 400 + bhp
with another 190,000 on the engine in total...

Tells what? How many hours under WOT? How long bursts under WOT? 5, 10, 20, 30 or 60 seconds? Usually cars in normal traffic are off-boost 95% of the time.

Originally Posted by ylee coyote

The 234 block=235 block
Its the pistons/conrods/crank? are different
the t7 head is better ..so keep that

What comes to flow, T7 head is better. We measured T7 head with std valves here in Finland. T7 valves ( especially exhaust ones ) are said to be a weak point ( 5mm vs. 7mm shaft ), but I've personally ever heard of the valve failures in this head.

Originally Posted by ylee coyote

change the bottom end ,get the best of both worlds...

You can buy a recon 234 block with rings and bearings for £600....

If we are building high power saab with minimal budget, this is not the worst choice at all. Another question is, if it's wise to build 500 hp engine with standard parts. These parts are not tested or meant for this kind of thermal conditions. Think the situation when you are driving your saab at 300 kph / 6700 RPM... Holset pushes steady 1,8 bar and it's not so nice to be in your saab in that speed. Can you trust your used 234 block with std internals in this situatjon? What happens if your used std piston or rod breaks?

Std parts ( pistons, rings, rods, valves etc ) last much longer ( what comes to hp ) than people usually think. If everything is under control ( a/r, temperatures etc. ), there is no doubt that one can push high hp:s out of B23x for short times under optimal circumstances with standard internals. The question is, though, how many hard accelerations this kind of machine will last?

In real world even engines with proper high quality forged internals wont usually last too long. This is because the use is so hard and there are always numerous unknown factors involved ( different temperatures, fuel quality, failures of normal maintenance parts like spark plugs, uneven fuelling between cylinders etc etc). Wear is excessive under excessive conditions. This kind of engines ( 500 hp -> ) are not meant for hundreds of thousands of kilometres... Rebuilding is usually necessary ( and wise because of the reliability ) after 20, 30 or 40 thousand kilometers ( in maximum ). And here we are speaking cars which are used in normal traffic, with some time on track occasionally.

If you can buy used standard pistons and rods of B234 for price X, engine failure later because of these cheap standard parts can cost you ( 3 * X ) later - or even your life. By using more expensive special parts in the first place can cost you three times more now, but can will save you a lot when time goes on.

And back to real, concrete world. How many 500 hp ( or 400 hp -> ) saab ( T5 or T7 or standalone EMS, no matter) people here really know? It's so easy to tell stories, which tend usually come better and better in the long run. Or put it in this way: How many here owns currently a saab with 400 hp + power ? Saab with this kind of power, which are driven in normal traffic are very rare even in Sweden. Commercial dynoqueens used by tuning companies can be excluded here...

And one should remember, that 500 hp cars can be very dangerous even with good technique. It's not clever to add some more risks by using those cheap junkyard parts.

Just my 0.02.