Horsepower estimate

[rgoodrich]

My 81 SC engine is being rebuilt. I am putting in Euro 9.8:1 Pistons(budget wouldn't allow Max Moritz conversion) and a 964 cam from Dougherty. Heads are freshened with titanium retainers. I have a Fabspeed header/dual in and dual out. Intake is Fabspeed cover and K&N filter,
I know that only a dyno can give real world horsepower ratings, but the closest one to me is 3 hours away, and I'll need a few miles on a new motor anyway.
I'm guessing about 210-215 crank hp, but I'd like opinions from others with more experience.
Estimates, please?

[SC-targa]

A late model euro 3.0 with milder cams, but bigger intake ports and runners made 204 HP (DIN). That's about 195 SAE NET HP at the flywheel.

You have a slightly better cam and a freer flowing exhaust, but your top end will be choked off a bit by the small intake ports and runners. You will likely also need to recurve the distributor.

I'm guessing 200 to 205 HP?

Regards,

Jerry Kroeger

[afterburn 549]

yup

[rgoodrich]

Thanks, guys. Any recommendations on who to use for the distributor recurve?

[Jeff Alton]

Send the distributor to Steve Wiener at Rennsport Systems for a recurve.

Your motor likely makes close to 210 hp. The cams and compression, if actual CR is 9.8, will add some and the exhaust change you made will make good gains. The airbox will net you zero.

I have built a couple of 3.0 motors with 964 cams and they are great fun motors.

Cheers

[rgoodrich]

Thanks for the info and support. I am supposed to get my car back from the builder Friday, so figure I'll see it next week. In addition to the engine mods, I had them use WEVO motor and trans mounts, and a Patrick flywheel. My Recaro Sportlines and Schroth harnesses came in too. I'm like a kid on Christmas Eve. I can't wait to get rolling!Detween the Mahle's and the cam I am looking forward to feeling the difference.
I have spoken to Steve before. I wish I had used him as a parts store, because the big name shop I used showed poor attention to detailI will get my distributor to Steve as soon as I can. Any danger to waiting 1000 miles?
When driving it before, I seemed to have good power. It turns out that I had badly worn out stock P&C's and a worn down cam, with a scuffed lobe, before this rebuild. I did have the headers/exhaust. Any guesses on my previous horsepower? I'm just trying to figure the difference between old power and new.

[don gilbert]

do you want to see hp on paper,, or do you want to feel it? I have played with my set up (close to yours) and i have finally set on running the 964 cams a little slow, you can feel the torque so much better, and more power on bottom end, better drivability, and you wont want to redline it constantly. The 964 cam set up makes a lot of diff. on the higher comp. and modified 3.0 (exhaust gearing and fuel mods) I think you would have no prob. putting down 210 or more to the rear wheels if you play with it on the dyno enough.

[rgoodrich]

Don,
I appreciate the input. The feel is of course, the most important thing. It sounds like you got a lot out of your CIS. What changes did you make? Were these changes done on the dyno?

[don gilbert]

don't tell anyone, but i take my car to an 1/8 mile track in holly spring miss. alot. the key to getting the most out of any engine is proper afr and spark at all levels of performance and atmospheric conditions This cannot be done on a cis car. (no mapp sensor) It can be overcome somewhat with an electronically adj. control pressure regulator, or warm up reg. as most call it. But those are expensIve, over 500.00. So i built my own, works very well, i have an afr gauge and a control press. gage in my dash, and run the InnovatIve Motor Sport wide band 02 with data logging. Its pretty cool, i can dial up control press to 60 on the hwy and get close to 30 mpg, or down to 45 when i want to play. On a very cold day of around 25-35 degrees f. you can run as low as 35lbs and car feels like 300 hp. but you can see the fuel needle move almost. And it fun to look at afr on a computer screen. Of course car has to be in proper tune and timed correctly. I run 35 max advance and use 93 shell, Ive done so much tinkering on cis it would take a lot of space and remembering. One thing i have found out, the factory air box lid is the way to go, Ive been down the track every which way, always the best time with a stock (but polished and deburred) lid and k&n, but don't use the k and n on the street. It is a very well designed velosity stack, no matter what mod to the engine

[Hotwatermusic]

Originally Posted by don gilbert

don't tell anyone, but i take my car to an 1/8 mile track in holly spring miss. alot. the key to getting the most out of any engine is proper afr and spark at all levels of performance and atmospheric conditions This cannot be done on a cis car. (no mapp sensor) It can be overcome somewhat with an electronically adj. control pressure regulator, or warm up reg. as most call it. But those are expensIve, over 500.00. So i built my own, works very well, i have an afr gauge and a control press. gage in my dash, and run the InnovatIve Motor Sport wide band 02 with data logging. Its pretty cool, i can dial up control press to 60 on the hwy and get close to 30 mpg, or down to 45 when i want to play. On a very cold day of around 25-35 degrees f. you can run as low as 35lbs and car feels like 300 hp. but you can see the fuel needle move almost. And it fun to look at afr on a computer screen. Of course car has to be in proper tune and timed correctly. I run 35 max advance and use 93 shell, Ive done so much tinkering on cis it would take a lot of space and remembering. One thing i have found out, the factory air box lid is the way to go, Ive been down the track every which way, always the best time with a stock (but polished and deburred) lid and k&n, but don't use the k and n on the street. It is a very well designed velosity stack, no matter what mod to the engine

Have you documented this modification in further detail in any previous thread? I'd love to see the whole procedure, with the parts and steps required to do it. It sounds like you've made the best of the CIS, for sure.

[don gilbert]

Its all documented in my head. Those pic of are actually of the third car I'm doing this to. I laugh when people say you cant get decent hp from cis. I know for a fact that 225 can be had at the rear wheels with cis, granted not on a stock 3.0, but you can make more than you think. I tuned a sc with carbs, and i know carbs to, hot little motor, but could only get 202 at the wheel. Plus he gets around 13 mpg, i get up to 28.1 (documented) That why when someone post, "thinking about carbs on my sc" I just cringe. CIS maybe outdated, But once you learn you dont need alot the stuff on the system (aar aav decel valve, and the prehistoric wur, it gets easier. And not to be bragging, but i was a master BMW tech at Coker BMW in tx for 16yrs. I somewhat know what I'm doing,(some of the time) but i am aways learning new things.and i think some closed minded K-jet running brothers should look at something new.

[SpeedracerIndy]

I did a dyno pull on my euro (9.8:1) SC. It's stock with SSIs. I got 182hp and 175tq to the wheels. Figuring the usual 15% drivetrain loss, that's around 210hp. Not exactly your same setup, but it's close. I'm not sure what 964 cams and a recurved dizzy will do for HP.

I was a little disappointed considering all the money I spent on exhaust, but I think I have some CIS issues so there should be some headroom.

[Vin-barrett]

Originally Posted by SC-targa

You will likely also need to recurve the distributor.

I have the engine described here, 1983 small port USA engine with 9.8 P/C's from the 930/10 engine. Same 964 cams from Dougherty only with SSI's and bursch muffler. Stock CIS, O2 disconnected.
My distributor is not modified only the vacuum retard is plugged. If I remember my timing is advanced slightly more than stock.

Why is it recommended to recurve the distributer? Is there much hp left on the table here?
IMO these changes to the engine are pretty minor...

As a side note to the OP I am actually pretty happy with the engine. Possibly the smaller ports make the car feel stronger at the bottom end. Sorry no dyno numbers...

[Superman]

I've got a late ('83) SC with 20/21 cams (aka 964+). Stock 9.3:1 pistons. SSI's. It made about 175 hp and 175 lb/ft at the wheels one day. Ignition advanced almost seven degrees. With 15% drive train loss, that's around 205 at the flywheel. The dyno guy kept staring at my p[ower curve, saying it looked like a V8 power curve. Lots of bottom end. Fun to drive.

[rgoodrich]

It sounds like a lot of people have very similar set ups to mine. I appreciate the input and information.It is reassuring to hear that everyone likes a 3.0 set up this way.
When my credit cards recover from the melt down, I will check around and see if there is a shop in Phoenix or Vegas that is familiar with hot rodding CIS. It sounds like it would be fun to basically dial in mpg and horsepower on the go. Any downside to these mods?

[Gunter]

Hot-rodding CIS?

Somewhat limited especially when dealing with AirCare.

Concentrate on the distributor. I's nearly 30 years old and who knows where the curve is?
IMHO, Distributors are the most neglected part on an engine. Even if you clean/oil yours, you still don't know if the curve is right for your set-up.

The question is not why should one re-curve but why not? Anytime one changes the specs, the timing needs attention.
Of course it has an effect on performance.

With 9.8 CR, single plug and crappy gas you don't want detonation. Have the distributor re-curved to run without vacuum for your engine.
Steve Weiner, if he has time, is one of the experts.

Contact him about this. I removed the vac pod, made a small SS cover for the hole and shipped it to Steve who re-curved it for my 9.8 CR SS 3.2 with CIS and 964 cams.

The engine loves it.

[SpeedracerIndy]

Originally Posted by rgoodrich

It sounds like a lot of people have very similar set ups to mine. I appreciate the input and information.It is reassuring to hear that everyone likes a 3.0 set up this way.
When my credit cards recover from the melt down, I will check around and see if there is a shop in Phoenix or Vegas that is familiar with hot rodding CIS. It sounds like it would be fun to basically dial in mpg and horsepower on the go. Any downside to these mods?

Downside? The only downside I can think of is the whole CIS part. Save up your money and ditch it for carbs or an efi setup.

Mine isn't a "mod" since it came that way from the motherland (with the exception of the SSIs), but it's very similar to what you will end up with. Compared to all the SCs and Carreras I've driven, it's very torquey (is that a word?) and pleasant to drive around town. Before I put it away for the winter, I surprised a guy in a bran new Audi S5. I don't' think he expected a 30 year old Porsche to be able to keep up with him so easily!

[Hotwatermusic]

Originally Posted by don gilbert

Its all documented in my head. Those pic of are actually of the third car I'm doing this to. Ive tried before to post my thoughts on cis here, but nobody seems to interested, or tell me I'm crazy, I laugh when people see you cant get decent hp from cis. I know for a fact that 225 can be had at the rear wheels with cis, granted not on a stock 3.0, but you can make more than you think. I tuned a sc with carbs, and i know carbs to, hot little motor, but could only get 202 at the wheel. Plus he gets around 13 mpg, i get up to 28.1 (documented) That why when someone post, "thinking about carbs on my sc" I just cringe. CIS maybe outdated, But once you learn you dont need alot the stuff on the system (aar aav decel valve, and the prehistoric wur, it gets easier. And not to be bragging, but i was a master BMW tech at Coker BMW in tx for 16yrs. I think now i know what I'm doing,(some of the time) but i am aways learning new things.and i think some closed minded K-jet running guy should look at something new.

I believe you, and I want to know more. If you could PM me or post a thread with a simple check list of parts and procedure for what you've done, I for one would greatly appreciate it. I see you've listed a lot of the parts you don't need on the CIS, but I'm sure it's not as simple just removing them and carrying on, so I'd really like to read about that procedure as well. I've read a thousand reasons why CIS sucks, anyone can write that. It's really good to see someone not going with the crowd. Share your knowledge!

[don gilbert]

Hotwatermusic I like you already. I was born and raised in Dallas and visited Austin regularly back in my youth. Is there still an awesome music scene there? I will gather up my thoughts and see if i can post a comprehensible thread if anybody is interested, What I'm doing is actually nothing new, i just have access to some very knowledgeable old school K jet techs from my bimmer days that where into dirt track racing 320's and 2002s back in the late 70s and early 80s. They told me that correct control press. at all times is the key to cis. performance. they actually had regulators with knobs in the cockpit. the 50-55 lb spec in the book is just a happy medium, I just took it from there and started experminting. I used to control my control press. with a rheostat hooked up to the stock wur. It worked pretty well but took a while for press to drop once it was warmed up. I had the wur mounted on phenolic blocks, but I like being able to adjust on the fly instantly with the turn of a knob.

[mickey356]

Don,
I'm always willing to learn something new about the CIS as well. When the time comes, I'll be doing pretty much the same set up (CIS, 964 cams, SSI's). I think carbs are a great option for a track car or a car that you only drive when the conditions are right. I drive my car EVERYDAY so I want something that works in all conditions, temps, etc..... post away please.