HP vs $$$ for SC engine mod
09-25-2002, 08:43 PM
#46
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[quote]Originally posted by Bill Verburg:
<strong>Some states have 25 yr law. Check you loacal DMV regs.</strong><hr></blockquote>
California's current rule is pre 1974 with a rolling 30 year exemption. 1974 cars will be clear in 2004, and my car will be exempt from semi-annual checks in 2012. The state keeps threatening to repeal the 30 year thing, so realistically there is no way to know.
As to getting a 964 distro approved, I don't think it is an option, because it has to come from the manufacturer. I am not worried about it all that much, it will just require another part be swapped out every 2 years. I already need to change the exhaust system and oil lines, spinning the crank to Z1 and swapping in the old distributor will just be another half hour, plus the cost of finding a servicable SC distributor for the conversion. Hell, I know people who have boxes of stuff they swap out every 2 years, this is easy compared to what they go through.
What it really boils down to at this point is money. Do I really want to spend an extra $4000+ above and beyond what is needed to get the car back on the road. On the other hand, I haven't torn down the engine yet, so I really don't know what is needed to get the car back on the road. I am assuming it just needs a top end, but I may find that I need new P&C anyway, which will make the decision a little easier. I may hit the jackpot and find I have Mahle P&C's in perfect condition, which I could sell to offset the cost of the swap.
Thanks everyone.
Tom
<strong>Some states have 25 yr law. Check you loacal DMV regs.</strong><hr></blockquote>
California's current rule is pre 1974 with a rolling 30 year exemption. 1974 cars will be clear in 2004, and my car will be exempt from semi-annual checks in 2012. The state keeps threatening to repeal the 30 year thing, so realistically there is no way to know.
As to getting a 964 distro approved, I don't think it is an option, because it has to come from the manufacturer. I am not worried about it all that much, it will just require another part be swapped out every 2 years. I already need to change the exhaust system and oil lines, spinning the crank to Z1 and swapping in the old distributor will just be another half hour, plus the cost of finding a servicable SC distributor for the conversion. Hell, I know people who have boxes of stuff they swap out every 2 years, this is easy compared to what they go through.
What it really boils down to at this point is money. Do I really want to spend an extra $4000+ above and beyond what is needed to get the car back on the road. On the other hand, I haven't torn down the engine yet, so I really don't know what is needed to get the car back on the road. I am assuming it just needs a top end, but I may find that I need new P&C anyway, which will make the decision a little easier. I may hit the jackpot and find I have Mahle P&C's in perfect condition, which I could sell to offset the cost of the swap.
Thanks everyone.
Tom
09-26-2002, 03:27 AM
#48
There is no problem mixing running the 964 cams, 98mm pistons on a cis system. One of my best friends runs that setup with no problems. Also, I find the european 81-83 cis system superior to the earlier us and euro systems, with the exception of the 3.0 carrera's which runs the same compression ratio as the later euros. Since the 81-83 euro cars came with 9.8:1 compression and no knock-sensor, they needed better fueling to counteract detonation. Of course this is hypothetical, but when you drive those cars, you clearly see that there is more going on there than just higher compression. In my us 80 sc, I have completely removed the lambda system (the box got flooded in a rainstorm), changed over to the late euro fuel distributor and warm-up regulator. It feels better and at 210,000 un-rebuilt miles and no ssi's, puts out 177 hp to the rear wheels. I'm not complaining. Too bad I don't have the larger intake ports.
As far as pistons and displacement, Arnold Wagner, one of the owners of Andial, had a 3.7 liter, twin-plug sc cis motor in his personal car. I found this out a few years back when talking to him about cis. While I was talking about its weaknesses, he was discounting them and praising the system. He apparently loved cis and applauded it for it's inherent simplicity, reliability and ability to easily pass emissions day after day. Considering the nature of the man's business and the infinite ways he could have gone, it was interesting to see that he went with cis in that displacement. He just really liked cis and was able to change my mind. It was definetely a sleeper, even with the decklid open for the world to see. You would have to tear the engine down to see the modifications.
He explained to me that cis can handle a lot of airflow before it becomes a problem. For evidence, just take a look at the 934 turbo at 485hp with cis. Of course, those are the upper limits of cis. But quite high nonetheless. Of course, the 934 had a few airflow tricks like a little aerodynamic cone to increase airflow through the sensor plate and few others. But there was certainly a lot more airflow there than in a normally aspirated motor.
Cis has a few weaknesses but none as major as it's inability to cope with wild cams. But this inability is also present with motronic. The 964 cams should not present a problem with a larger displacement. The main problem that arises from going any larger than a 3.4 liter displacement is the offseting of the spark plug in relation to the combustion chamber. At a 3.5 liter displacement or more, twin-plugs start to become a necessity to get an even combustion. That is why a lot of people don't bother going over 3.4. Especially considering that 3.4 is a straight bolt-on deal.
One of the reasons for the high cost of oversize Mahle pistons has been the fact that there has only been one source in the US for a long time. And that is Andial. I have a feeling that Brumos is now selling them also. Then there is the other fact that you get new Nikasil cylinders along with the pistons. With that in mind, one can start to understand the higher cost.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
As far as pistons and displacement, Arnold Wagner, one of the owners of Andial, had a 3.7 liter, twin-plug sc cis motor in his personal car. I found this out a few years back when talking to him about cis. While I was talking about its weaknesses, he was discounting them and praising the system. He apparently loved cis and applauded it for it's inherent simplicity, reliability and ability to easily pass emissions day after day. Considering the nature of the man's business and the infinite ways he could have gone, it was interesting to see that he went with cis in that displacement. He just really liked cis and was able to change my mind. It was definetely a sleeper, even with the decklid open for the world to see. You would have to tear the engine down to see the modifications.
He explained to me that cis can handle a lot of airflow before it becomes a problem. For evidence, just take a look at the 934 turbo at 485hp with cis. Of course, those are the upper limits of cis. But quite high nonetheless. Of course, the 934 had a few airflow tricks like a little aerodynamic cone to increase airflow through the sensor plate and few others. But there was certainly a lot more airflow there than in a normally aspirated motor.
Cis has a few weaknesses but none as major as it's inability to cope with wild cams. But this inability is also present with motronic. The 964 cams should not present a problem with a larger displacement. The main problem that arises from going any larger than a 3.4 liter displacement is the offseting of the spark plug in relation to the combustion chamber. At a 3.5 liter displacement or more, twin-plugs start to become a necessity to get an even combustion. That is why a lot of people don't bother going over 3.4. Especially considering that 3.4 is a straight bolt-on deal.
One of the reasons for the high cost of oversize Mahle pistons has been the fact that there has only been one source in the US for a long time. And that is Andial. I have a feeling that Brumos is now selling them also. Then there is the other fact that you get new Nikasil cylinders along with the pistons. With that in mind, one can start to understand the higher cost.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
09-26-2002, 11:56 AM
#49
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As stated in my original post, my car is a US spec, dead stock 79 SC and I do not have to worry about emission.
If I go with 98mm P&C, 964 cams and SSI, will my CIS injection be adequate? If not, what should I do? Is my injection system better or worst than the 80-83 CIS-Lambda system?
How many HP could I expect from such a set-up?
As my engine is almost brand new (believe it or not my car has only 16,000 miles), an alternative could be to get only the SSI, 964 cams and replace the gear ratios in the transmission. What ratios should I get for 2nd through 4th gears?
I feel 2nd and 3rd would be the most important to change and should be lowered by about 15%. 4th by maybe 7%? Am I right?
If I go with 98mm P&C, 964 cams and SSI, will my CIS injection be adequate? If not, what should I do? Is my injection system better or worst than the 80-83 CIS-Lambda system?
How many HP could I expect from such a set-up?
As my engine is almost brand new (believe it or not my car has only 16,000 miles), an alternative could be to get only the SSI, 964 cams and replace the gear ratios in the transmission. What ratios should I get for 2nd through 4th gears?
I feel 2nd and 3rd would be the most important to change and should be lowered by about 15%. 4th by maybe 7%? Am I right?
09-26-2002, 02:17 PM
#50
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For what it's worth, I re-read Bruce Anderson's chapter on performance mods last night, he says with the Max Moritz 98mm P&C sets,and reseting the fuel mixture they were claiming 220HP.
With 9.8:1 compression the 81-83 Euro SC's got 204hp. Using the same hp/litre the factory got, 3.2 litre comes out to 217 hp. Euro motronic 3.2's had 231 HP.
I know there is more to it than that, but the 220 number doesn't sound unreasonable.
I need to get a night job to afford all the stuff I want to do.
Tom
With 9.8:1 compression the 81-83 Euro SC's got 204hp. Using the same hp/litre the factory got, 3.2 litre comes out to 217 hp. Euro motronic 3.2's had 231 HP.
I know there is more to it than that, but the 220 number doesn't sound unreasonable.
I need to get a night job to afford all the stuff I want to do.
Tom
09-26-2002, 03:40 PM
#51
RL Technical Advisor
[quote]Originally posted by Denis54:
<strong>As stated in my original post, my car is a US spec, dead stock 79 SC and I do not have to worry about emission.
If I go with 98mm P&C, 964 cams and SSI, will my CIS injection be adequate? If not, what should I do? Is my injection system better or worst than the 80-83 CIS-Lambda system?
How many HP could I expect from such a set-up?
As my engine is almost brand new (believe it or not my car has only 16,000 miles), an alternative could be to get only the SSI, 964 cams and replace the gear ratios in the transmission. What ratios should I get for 2nd through 4th gears?
I feel 2nd and 3rd would be the most important to change and should be lowered by about 15%. 4th by maybe 7%? Am I right?</strong><hr></blockquote>
Hi Denis:
Your CIS is able to handle the mods that you wish to do; no worries, Sir. 220HP is not unreasonable if everything is done right.
Gear ratio selection is done by factoring your ring & pinion ratio, your rear tire size and what RPM range you will need. One would need that data as well as what cruise RPM you can tolerate and what top speed you want.
I have a good street-ratio gearstack on my website for a 915 with 8:31 and 225/50-16 tire in the "Let's Talk" section on Transmissions....
<strong>As stated in my original post, my car is a US spec, dead stock 79 SC and I do not have to worry about emission.
If I go with 98mm P&C, 964 cams and SSI, will my CIS injection be adequate? If not, what should I do? Is my injection system better or worst than the 80-83 CIS-Lambda system?
How many HP could I expect from such a set-up?
As my engine is almost brand new (believe it or not my car has only 16,000 miles), an alternative could be to get only the SSI, 964 cams and replace the gear ratios in the transmission. What ratios should I get for 2nd through 4th gears?
I feel 2nd and 3rd would be the most important to change and should be lowered by about 15%. 4th by maybe 7%? Am I right?</strong><hr></blockquote>
Hi Denis:
Your CIS is able to handle the mods that you wish to do; no worries, Sir. 220HP is not unreasonable if everything is done right.
Gear ratio selection is done by factoring your ring & pinion ratio, your rear tire size and what RPM range you will need. One would need that data as well as what cruise RPM you can tolerate and what top speed you want.
I have a good street-ratio gearstack on my website for a 915 with 8:31 and 225/50-16 tire in the "Let's Talk" section on Transmissions....
