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Discussion Starter #1
After looking at some cam specs posted by Nick Taliafferro recently, and noting his 15 or so hp improvement switching to the B234R cams, I noticed that the B234i cams (from the naturally aspirated 2.3L) are particularly aggressive.

I also happen to have a piece of software called "Desktop Dyno" ... which allows me to put in exactly the cam specs that Nick listed and get fairly accurate results. Unfortunately the program does not account for turbocharged engines.

Generally to simulate a 4 cyllinder turbo Saab engine on that program I just use the stock Bore and Stroke from Saab, then multiply the number of cyllinders by the pressure ratio between intake and ambient. For the Viggen this makes it equivalent to 8 cyllinders. The Viggen also suffers from a boost taper towards redline, however this is partially accounted for because when you make it an 8 cyllinder engine, you double the frictional losses. As it turns out those two things seem to cancel out nicely. Just guesstimating at the setup, and putting in the stock cam specs got me to within 5 hp of my actual dyno results, and within 10 lb ft of torque. All suprisinging, at exactly the right rpm.

Next, because changing cams can affect turbo cars differently than Naturally aspirated V8's, I tried putting in the cams that Nick put into his Viggen and looking at the results. They were also nearly spot on, lending about a 15 horsepower increase in the higher revs, with a very slight decrease down low. Excellent
...

Then I put in the naturally aspirated cam specs and gained about another 17 horses. Doesn't seem like a lot ... but that's over 30 additional horsepower from stock! The affect was similar on the T7 2.0 (B205R) which also netted about 30 extra ponies up top. However the older 2.3 and 2.0 are likely only to see about 10-15 horsepower.

Before everyone runs out to buy cams though, there are some things to comsider.

Firstly ... if you have a T5 car, the adaptability of the speed density fueling system to account for the increase in volumetric efficiency is limited. But if it makes you feel better, T5 cars already have cams that are pretty aggresive, so it won't be a huge difference.

Secondly ... T7 cars should be able to adapt, the MAF sensor should register the changes and the partial speed density system will adapt to the new cams. However you will be pushing the stock injectors, and it would be wise to buy an uprated Fuel Pressure Regulator. The T7 computer will adapt to this as well, so you won't run overly rich, but you will have some extra margin to make sure you don't run lean either.

Thirdly ... it's hard to say how this would affect gas mileage. Since the VE is lower at cruising RPM it should in theory go up. A lower VE simulates a smaller engine. But things like valve overlap also affect gas mileage. The Naturally Aspirated cams have less than the T7 2.3 cams, but more than the T5 cams. One could assume the mileage would be somewhere between those two.

Now it's just a matter of testing this out. And of course, finding a place that sells B234i camshafts. Oh and btw, as far as performance upgrades go in relation to your warranty, this one would be nearly impossible for the dealer, or anyone else, to spot. A very stealthy mod. Sleeper town ...

Dubbya~
 

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Wouldn’t it be nice if you had a few sets on the shelf…
I have been planning on it for some time. Just too busy.
To tell the truth when I was looking for the cams I ran across the GM900 2.3NA inlet manifold. longer runners. Bigger plenum. I have been spending some time modifying it to work with t7 since it has quite different throttle body and sensor details.

I am still not sure how T7 will react to a larger plenum and longer runners. Only one way to find out.
Results in 2 weeks.

NCT
 

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I took some time today at lunch and dropped the 234i cams in my modified viggen. Took about 30 min.

Seem to remove some of the midrange boost lag. Not sure about overall power but the drivability seems better.

I will have to wait and see what the dyno says.

NCT
 

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Discussion Starter #4
The T7 software may prevent any actual increase in power per se ... but it would either get more power, or the same power with less boost pressure. Which I think is a good thing either way.

If T7 keeps the same boost setting across the entire powerband, rather than basing the boost pressure on airflow, it will be worth 14 hp or so over the B234R cams, and 30 over the stock Viggen cams.

I actually have been running tons of simulations and I still cannot find a better cam spec anywhere! Even really expensive camshafts from HKS (for the Evo), upgraded cams for various other DOHC engines, every cam combination my software comes with, and any variations that I can come up with aren't as good as those N/A cams for the Saab engine!

In fact they work extremely well on nearly any DOHC engine. Some other specs will offer maybe a 5% higher peak hp, but then a 20% drop in torque! While these B234i cams maintain HUGE high rpm power (I'm talking all the way up to 8,000 rpm easily) and they maintain really really good torque down-low compared to nearly every other DOHC camshaft I could find.

They aren't an instant power elixor, but they are honestly very very good. Another big thing you can do with Saab engines is get uprated valves. Again this isn't "necessary" with turbo engines to get power, as you're usually more worried with knock than flow, and to compensate for flow you just up the boost. But a complete set of Titanium valves can be aquired for under $500 including a new headgasket. That's about half the price of just one ECU upgrade to upgrade the boost with.

Some things to think about. Saab ECU upgrades are so expensive that things like camshafts are comparitively cheap. But like I said, it's just something to think about.

Dubbya~
 

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I notice from here that there are two types of B234i camshaft, pre and post -94. Timing on the early cams on the exh looks very slight different. Would this matter? Would they fit a >1994 B234T?

Thanks,

Alan
 

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That's good, it looks like thos of us with 91-93 2.3T's have either exactly B234i cams, or very nearly B234i cams (compared with 94- 2.3i's)



Andrew
 

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The 91-93 2.3T is widely acknowledged as being mechanically the best engine ever Saab built for strength/tuning
 

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Originally posted by Mark E:
[qb]The 91-93 2.3T is widely acknowledged as being mechanically the best engine ever Saab built for strength/tuning    :thumbsup:      :fawlty:  [/qb][/b]
Unfortunately the 1992 w. TCS appears to have the rarest and most difficult to tune APC system. Well, if you want more than 250bhp it is.
 

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Discussion Starter #10
Originally posted by Mark E:
[qb]The 91-93 2.3T is widely acknowledged as being mechanically the best engine ever Saab built for strength/tuning    :thumbsup:      :fawlty:  [/qb][/b]
Except that the head flows about 20% less than the T7 head.

I'mma run a few cam combinations through the simulator to see if I can get any better hp numbers. Obviously I can't simulate spool up, but if you're ever just tuning for outright power it could be of some help as the difference in spool up will be only slight with different cams.

Gonna also see if any of them are worth any power on muh C900 ... wooOOoo this should be fun. I love cam specs.


Dubbya~
 

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Discussion Starter #12
Originally posted by Jason (Mr Torque-Steer):
[qb]  QUOTE
Except that the head flows about 20% less than the T7 head.[/b]
Well that can be improved with some porting and polishing. I just wish it as straightforward to to retro fit a Trionic ECU. [/qb][/b][/quote]And then if you port and polish the T7 head? Besides the T7 head was designed years after the pre-trionic heads. It has vastly improved swirl characteristics. You'd never get the older heads to flow AND swirl as well as the T7 head ... course you COUld bolt on a T7 head, then you'd have the ultimate Saab longblock ... for performance anyway.

The weaker T7 pistons are actually a result of smaller ring lands, which are better for emmissions and fuel economy. So they're quite a nice feature on a 300 or less hp engine.

Still working out the cam specs. It appears the pre-trionic B234 head's cams are great for the later model cars. There's no real significant difference between them and the B234i cams ... so either pair should work. Assuming they can be swapped. The B234 91-93 cams should also contribute quicker spool up as noted on the page listing the specs. So since there's no huge difference in power, and quicker spool up they're not a bad way to go. I think they were like 4 hp less on simulation.

Dubbya~
 

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As an aside, Saabine is currently getting a ported, big-valve T7 head with bespoke intake manifold to make what's probably the ultimate longitudinally-mounted Saab engine...
 

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Discussion Starter #14
Originally posted by Eric van Spelde:
[qb]As an aside, Saabine is currently getting a ported, big-valve T7 head with bespoke intake manifold to make what's probably the ultimate longitudinally-mounted Saab engine...       [/qb][/b]
Except the Viggen hillclimb engine, which is also longitudinally mounted.

We'll just say it's gonna be the ultimate slanted longitudially mounted Saab engine, in a production Saab car. ... Err ... that we know of. (Good enough!)

Oh and of course we expect dyno sheets, videos, and pictures with lots of
involved when it's all back together.

Dubbya~
 

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Looks like the B234 Turbo cams are better than the B234 i non turbo variety for power. The latter feel smoother.. Almost Flat torque. Just reduced output!
Run 18 = NA cams Run 12 B234T cams Car 2001 Viggen Refrence document.pdf

Turbo cams make more midrange. NA more 2.5K-3K and above 5K are stronger.. I know there must be better combinations. The hard to quantify factors such as drivability and boost lag are not represented here. Any comments?

Still having fun...
Nick Taliaferro
 

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Discussion Starter #16
It looks like they were run on different days/temps. The Naturally Aspirated camshafts should have made it run lean-er if anything. Instead they appear the run richer.

Between 5500 and 6000 RPM it's making more power despite being quite a bit richer.

The intake cam from the 91-93 9000 is the same duration and lift as the Naturally aspirated cam, but the exhaust cam is timed later to increase spool up.

Also on the note of cams I just found the specs for the C900T 16V cars. They have an intake duration of 252 and exhaust duration of 254!
Probably not great for spool up, but would make some interesting top end when combined with the T7 high flow head.

Really is strange that it ran richer. Try a dyno run with some race fuel. Increasing the volumetric efficiency too much can make the car more detonation sensitive on the same boost.

Otherwise I blame different days for the dyno run. Temp and humidity will change power quite a bit, and the A/F ratio seems to show that. If it was the same day then the N/A cams probably weren't adapted into the ECU yet. Either way. Shouldn't have made it run rich.

Dubbya~
 
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